High voltage system: Plasma interaction summary

NASA Technical Reports Server (NTRS)

Stevens, N. John

1986-01-01

The possible interactions that could exist between a high voltage system and the space plasma environment are reviewed. A solar array is used as an example of such a system. The emphasis in this review is on the discrepancies that exist in this technology in both flight and ground experiment data. It has been found that, in ground testing, there are facility effects, cell size effects and area scaling uncertainties. For space applications there are area scaling and discharge concerns for an array as well as the influence of the large space structures on the collection process. There are still considerable uncertainties in the high voltage-space plasma interaction technology even after several years of effort.

Determination of Plasma Screening Effects for Thermonuclear Reactions in Laser-generated Plasmas

NASA Astrophysics Data System (ADS)

Wu, Yuanbin; Pálffy, Adriana

2017-03-01

Due to screening effects, nuclear reactions in astrophysical plasmas may behave differently than in the laboratory. The possibility to determine the magnitude of these screening effects in colliding laser-generated plasmas is investigated theoretically, having as a starting point a proposed experimental setup with two laser beams at the Extreme Light Infrastructure facility. A laser pulse interacting with a solid target produces a plasma through the Target Normal Sheath Acceleration scheme, and this rapidly streaming plasma (ion flow) impacts a secondary plasma created by the interaction of a second laser pulse on a gas jet target. We model this scenario here and calculate the reaction events for the astrophysically relevant reaction 13C(4He, n)16O. We find that it should be experimentally possible to determine the plasma screening enhancement factor for fusion reactions by detecting the difference in reaction events between two scenarios of ion flow interacting with the plasma target and a simple gas target. This provides a way to evaluate nuclear reaction cross-sections in stellar environments and can significantly advance the field of nuclear astrophysics.

Laser-Plasma Interactions on NIKE and the Fusion Test Facility

NASA Astrophysics Data System (ADS)

Phillips, Lee; Weaver, James

2008-11-01

Recent proposed designs for a Fusion Test Facility (FTF) (Obenchain et al., Phys. Plasmas 13 056320 (2006)) for direct-drive ICF targets for energy applications involve high implosion velocities combined with higher laser irradiances. The use of high irradiances increases the likelihood of deleterious laser plasma instabilities (LPI) but the proposed use of a 248 nm KrF laser to drive these targets is expected to minimize the LPI risk. We examine, using simulation results from NRL's FAST hydrocode, the proposed operational regimes of the FTF in relation to the thresholds for the SRS, SBS, and 2-plasmon instabilities. Simulations are also used to help design and interpret ongoing experiments being conducted at NRL's NIKE facility for the purpose of generating and studying LPI. Target geometries and laser pulseshapes were devised in order to create plasma conditions with long scalelengths and low electron temperatures that allow the growth of parametric instabilities. These simulations include the effects of finite beam angles through the use of raytracing.

Inertial Confinement Fusion quarterly report, January-March 1998, volume 8, number 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruer, W

1998-03-31

The coupling of laser light with plasmas is one of the key physics issues for the use of high-power lasers for inertial fusion, high-energy-density physics, and scientific stockpile stewardship. The coupling physics is extremely rich and challenging, particularly in the large plasmas to be accessed on the National Ignition Facility (NIF). The coupling mechanisms span the gamut from classical inverse bremsstrahlung absorption to a variety of nonlinear optical processes. These include stimulated Raman scattering (SRS) from electron plasma waves, stimulated Brillouin scattering (SBS) from ion sound waves, resonant decay into electron plasma and ion sound waves, and laser beam filamentation.more » These processes depend on laser intensity and produce effects such as changes in the efficiency and location of the energy deposition or generation of a component of very energetic electrons, which can preheat capsules. Coupling physics issues have an extremely high leverage. The coupling models are clearly very important ingredients for detailed calculations of laser-irradiated target behavior. Improved understanding and models enable a more efficient use of laser facilities, which becomes even more important as these facilities become larger and more expensive. Advances in the understanding also allow a more timely and cost-effective identification of new applications of high-power lasers, such as for generation of high-temperature hohlraums and compact x-ray sources, or for discovery of advanced fusion schemes. Finally, the interaction of intense electromagnetic waves with ionized media is a fundamental topic of interest to numerous areas of applied science and is an excellent test bed for advancing plasma science and computational modeling of complex phenomena. This issue of the ICF Quarterly Report is dedicated to laser--plasma interactions. The eight articles present a cross section of the broad progress in understanding the key interaction issues, such as laser beam bending, spraying, and scattering, as well as scaling the Nova results to NIF.« less

Plasma contactor technology for Space Station Freedom

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Hamley, John A.; Sarver-Verhey, Timothy; Soulas, George C.; Parkes, James; Ohlinger, Wayne L.; Schaffner, Michael S.; Nelson, Amy

1993-01-01

Hollow cathode plasma contactors were baselined for Space Station Freedom (SSF) to control the electrical potentials of surfaces to eliminate/mitigate damaging interactions with the space environment. The system represents a dual-use technology which is a direct outgrowth of the NASA electric propulsion program and in particular the technology development effort on ion thruster systems. Specific efforts include optimizing the design and configuration of the contactor, validating its required lifetime, and characterizing the contactor plume and electromagnetic interference. The plasma contact or subsystems include the plasma contact or unit, a power electronics unit, and an expellant management unit. Under this program these will all be brought to breadboard and engineering model development status. New test facilities were developed, and existing facilities were augmented, to support characterizations and life testing of contactor components and systems. The magnitude, scope, and status of the plasma contactor hardware development program now underway and preliminary test results on system components are discussed.

Plasma contactor technology for Space Station Freedom

NASA Technical Reports Server (NTRS)

Patterson, Michael J.; Hamley, John A.; Sarver-Verhey, Timothy; Soulas, George C.; Parkes, James; Ohlinger, Wayne L.; Schaffner, Michael S.; Nelson, Amy

1993-01-01

Hollow cathode plasma contactors have been baselined for Space Station Freedom to control the electrical potentials of surfaces to eliminate/mitigate damaging interactions with the space environment. The system represents a dual-use technology which is a direct outgrowth of the NASA electric propulsion program and in particular the technology development effort on ion thruster systems. Specific efforts include optimizing the design and configuration of the contactor, validating its required lifetime, and characterizing the contactor plume and electromagnetic interference. The plasma contactor subsystems include the plasma contactor unit, a power electronics unit, and an expellant management unit. Under this program these will all be brought to breadboard and engineering model development status. New test facilities have been developed, and existing facilities have been augmented, to support characterizations and life testing of contactor components and systems. This paper discusses the magnitude, scope, and status of the plasma contactor hardware development program now under way and preliminary test results on system components.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Yuanbin; Pálffy, Adriana, E-mail: yuanbin.wu@mpi-hd.mpg.de, E-mail: Palffy@mpi-hd.mpg.de

Due to screening effects, nuclear reactions in astrophysical plasmas may behave differently than in the laboratory. The possibility to determine the magnitude of these screening effects in colliding laser-generated plasmas is investigated theoretically, having as a starting point a proposed experimental setup with two laser beams at the Extreme Light Infrastructure facility. A laser pulse interacting with a solid target produces a plasma through the Target Normal Sheath Acceleration scheme, and this rapidly streaming plasma (ion flow) impacts a secondary plasma created by the interaction of a second laser pulse on a gas jet target. We model this scenario heremore » and calculate the reaction events for the astrophysically relevant reaction {sup 13}C({sup 4}He, n ){sup 16}O. We find that it should be experimentally possible to determine the plasma screening enhancement factor for fusion reactions by detecting the difference in reaction events between two scenarios of ion flow interacting with the plasma target and a simple gas target. This provides a way to evaluate nuclear reaction cross-sections in stellar environments and can significantly advance the field of nuclear astrophysics.« less

Electric Propulsion Test and Evaluation Methodologies for Plasma in the Environments of Space and Testing (EP TEMPEST)

DTIC Science & Technology

2016-04-14

Swanson AEDC Path 1: Magnetized electron transport impeded across magnetic field lines; transport via electron-particle collisions Path 2*: Electron...T&E (higher pressure, metallic walls) → Impacts stability, performance, plume properties, thruster lifetime Magnetic Field Lines Plasma Plume...Development of T&E Methodologies • Current-Voltage- Magnetic Field (I-V-B) Mapping • Facility Interaction Studies • Background Pressure • Plasma Wall

Plasma-wall interaction data needs critical to a Burning Core Experiment (BCX)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1985-11-01

The Division of Development and Technology has sponsored a four day US-Japan workshop ''Plasma-Wall Interaction Data Needs Critical to a Burning Core Experiment (BCX)'', held at Sandia National Laboratories, Livermore, California on June 24 to 27, 1985. The workshop, which brought together fifty scientists and engineers from the United States, Japan, Germany, and Canada, considered the plasma-material interaction and high heat flux (PMI/HHF) issues for the next generation of magnetic fusion energy devices, the Burning Core Experiment (BCX). Materials options were ranked, and a strategy for future PMI/HHF research was formulated. The foundation for international collaboration and coordination of thismore » research was also established. This volume contains the last three of the five technical sessions. The first of the three is on plasma materials interaction issues, the second is on research facilities and the third is from smaller working group meetings on graphite, beryllium, advanced materials and future collaborations.« less

A research program in magnetogasdynamics utilizing hypervelocity coaxial plasma generators

NASA Technical Reports Server (NTRS)

Spight, C.

1976-01-01

A broadly-gauged research program in magnetogasdynamics utilizing hypervelocity coaxial plasma generators is presented. A complete hypervelocity coaxial plasma generator facility was assembled and tested. Significant progress was made in the direction of understanding the important processes in the interaction of hypervelocity MGD flow with transverse applied fields. It is now proposed to utilize the accumulated experimental capability and theoretical analysis in application to the analysis and design parameterization of pulsed magnetogasdynamic direct energy convertor configurations.

Space Station Freedom solar array panels plasma interaction test facility

NASA Technical Reports Server (NTRS)

Martin, Donald F.; Mellott, Kenneth D.

1989-01-01

The Space Station Freedom Power System will make extensive use of photovoltaic (PV) power generation. The phase 1 power system consists of two PV power modules each capable of delivering 37.5 KW of conditioned power to the user. Each PV module consists of two solar arrays. Each solar array is made up of two solar blankets. Each solar blanket contains 82 PV panels. The PV power modules provide a 160 V nominal operating voltage. Previous research has shown that there are electrical interactions between a plasma environment and a photovoltaic power source. The interactions take two forms: parasitic current loss (occurs when the currect produced by the PV panel leaves at a high potential point and travels through the plasma to a lower potential point, effectively shorting that portion of the PV panel); and arcing (occurs when the PV panel electrically discharges into the plasma). The PV solar array panel plasma interaction test was conceived to evaluate the effects of these interactions on the Space Station Freedom type PV panels as well as to conduct further research. The test article consists of two active solar array panels in series. Each panel consists of two hundred 8 cm x 8 cm silicon solar cells. The test requirements dictated specifications in the following areas: plasma environment/plasma sheath; outgassing; thermal requirements; solar simulation; and data collection requirements.

The LENS Facilities and Experimental Studies to Evaluate the Modeling of Boundary Layer Transition, Shock/Boundary Layer Interaction, Real Gas, Radiation and Plasma Phenomena in Contemporary CFD Codes

DTIC Science & Technology

2010-04-01

Layer Interaction, Real Gas, Radiation and Plasma Phenomena in Contemporary CFD Codes Michael S. Holden, PhD CUBRC , Inc. 4455 Genesee Street Buffalo...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) CUBRC , Inc. 4455 Genesee Street Buffalo, NY 14225, USA 8. PERFORMING...HyFly Navy EMRG Reentry-F Slide 2 X-43 HIFiRE-2 Figure 17: Transition in Hypervelocity Flows: CUBRC Focus – Fully Duplicated Ground Test

Numerical design of a magnetized turbulence experiment at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Feister, Scott; Tzeferacos, Petros; Meinecke, Jena; Bott, Archie; Caprioli, Damiano; Laune, Jt; Bell, Tony; Casner, Alexis; Koenig, Michel; Li, Chikang; Miniati, Francesco; Petrasso, Richard; Remington, Bruce; Reville, Brian; Ross, J. Steven; Ryu, Dongsu; Ryutov, Dmitri; Sio, Hong; Turnbull, David; Zylstra, Alex; Schekochihin, Alexander; Froula, Dustin; Park, Hye-Sook; Lamb, Don; Gregori, Gianluca

2017-10-01

The origin and amplification of magnetic fields remains an active astrophysical research topic. We discuss design (using three-dimensional FLASH simulations) of a magnetized turbulence experiment at the National Ignition Facility (NIF). NIF lasers drive together two counter-propagating plasma flows to form a hot, turbulent plasma at the center. In the simulations, plasma temperatures are high enough to reach super-critical values of magnetic Reynolds number (Rm). Biermann battery seed magnetic fields (generated during laser-target interaction) are advected into the turbulent region and amplified by fluctuation dynamo in the above-unity Prandtl number regime. Plasma diagnostics are modeled with FLASH for planning and direct comparison with NIF experimental data. This work was supported in part at the University of Chicago by the DOE NNSA, the DOE Office of Science, and the NSF. The numerical simulations were conducted at ALCF's Mira under the auspices of the DOE Office of Science ALCC program.

Initial Ferritic Wall Mode studies on HBT-EP

NASA Astrophysics Data System (ADS)

Hughes, Paul; Bialek, J.; Boozer, A.; Mauel, M. E.; Levesque, J. P.; Navratil, G. A.

2013-10-01

Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective US component test facility and DEMO. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these experiments. Although the ferritic wall mode (FWM) was seen in a linear machine, the FWM was not observed in JFT-2M, probably due to eddy current stabilization. Using its high-resolution magnetic diagnostics and positionable walls, HBT-EP has begun exploring the dynamics and stability of plasma interacting with high-permeability ferritic materials tiled to reduce eddy currents. We summarize a simple model for plasma-wall interaction in the presence of ferromagnetic material, describe the design of a recently-installed set of ferritic shell segments, and report initial results. Supported by U.S. DOE Grant DE-FG02-86ER53222.

OFF-Stagnation point testing in plasma facility

NASA Astrophysics Data System (ADS)

Viladegut, A.; Chazot, O.

2015-06-01

Reentry space vehicles face extreme conditions of heat flux when interacting with the atmosphere at hypersonic velocities. Stagnation point heat flux is normally used as a reference for Thermal Protection Material (TPS) design; however, many critical phenomena also occur at off-stagnation point. This paper adresses the implementation of an offstagnation point methodology able to duplicate in ground facility the hypersonic boundary layer over a flat plate model. The first analysis using two-dimensional (2D) computational fluid dynamics (CFD) simulations is carried out to understand the limitations of this methodology when applying it in plasma wind tunnel. The results from the testing campaign at VKI Plasmatron are also presented.

Trident Laser Facility

Science.gov Websites

-trillion watt Trident Laser enters from the bottom to interact with a one-micrometer thick foil target in tens of millions of volts. In this time-integrated image, one sees many colorful plasmas that result from the bottom to interact with a one-micrometer thick foil target in the center of the photo. In this

The Colorado Solar Wind Experiment

NASA Astrophysics Data System (ADS)

Munsat, Tobin; Han, Jia; Horanyi, Mihaly; Ulibarri, Zach; Wang, Xu; Yeo, Lihsia

2016-10-01

The Colorado Solar Wind Experiment (CSWE) is a new device developed at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT) at the University of Colorado. This large ion source is for studies of the interaction of solar wind plasma with planetary surfaces and cosmic dust, and for the investigation of plasma wake physics. With a plasma beam diameter of 12 cm at the source, ion energies of up to 1 keV, and ion flows of up to 1 mA/cm2, a large cross-section Kaufman Ion Source is used to create steady state plasma flow to model the solar wind in an experimental vacuum chamber. Chamber pressure can be reduced to 3e-5 Torr under operating conditions to suppress ion-neutral collisions and create a uniform ion velocity distribution. Diagnostic instruments such as a double Langmuir probe and an ion energy analyzer are mounted on a two-dimensional translation stage that allow the beam to be characterized throughout the chamber. Early experiments include the measurement of dust grain charging from the interaction with flowing plasma, and measurements of the plasma sheath created by the interaction of the flowing plasma impinging on a surface with a dipole magnetic field. This poster will describe the facility and the scientific results obtained to date.

Plasma-material Interactions in Current Tokamaks and their Implications for Next-step Fusion Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Federici, G.; Skinner, C.H.; Brooks, J.N.

2001-01-10

The major increase in discharge duration and plasma energy in a next-step DT [deuterium-tritium] fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety, and performance. Erosion will increase to a scale of several centimeters from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma-facing components. Controlling plasma wall interactions is critical to achieving high performance in present-day tokamaks and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of themore » important consequences of these phenomena has stimulated an internationally coordinated effort in the field of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) project and significant progress has been made in better under standing these issues. This paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next-step fusion reactors. Two main topical groups of interactions are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation, (ii) tritium retention and removal. The use of modeling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D [Research and Development] avenues for their resolution are presented.« less

The concept of a facility for cosmic dust research on the International Space Station

NASA Technical Reports Server (NTRS)

Blum, Juergen; Cabane, Michel; Fonda, Mark; Giovane, Frank; Gustafson, Bo A. S.; Keller, Horst U.; Markiewicz, Wojciech J.; Levasseur-Regourd, Any-Chantal; Worms, Jean-Claude; Nuth, Joseph A.;

Promoting Pre-college Science Education

NASA Astrophysics Data System (ADS)

Taylor, P. L.; Lee, R. L.

2000-10-01

The Fusion Education Program, with continued support from DOE, has strengthened its interactions with educators in promoting pre-college science education for students. Projects aggressively pursued this year include an on-site, college credited, laboratory-based 10-day educator workshop on plasma and fusion science; completion of `Starpower', a fusion power plant simulation on interactive CD; expansion of scientist visits to classrooms; broadened participation in an internet-based science olympiad; and enhancements to the tours of the DIII-D Facility. In the workshop, twelve teachers used bench top devices to explore basic plasma physics. Also included were radiation experiments, computer aided drafting, techniques to integrate fusion science and technology in the classroom, and visits to a University Physics lab and the San Diego Supercomputer Center. Our ``Scientist in a Classroom'' program reached more than 2200 students at 20 schools. Our `Starpower' CD allows a range of interactive learning from the effects of electric and magnetic fields on charged particles to operation of a Tokamak-based power plant. Continuing tours of the DIII-D facility were attended by more than 800 students this past year.

Colliding Laser-Produced Plasmas on LaPD

NASA Astrophysics Data System (ADS)

Collette, Andrew; Gekelman, Walter

2008-11-01

The expansion and interaction of dense plasmas in the presence of a magnetized background plasma is important in many astrophysical processes. We describe a series of experiments which involve the collision of two dense (initially n > 10^15cm-3) laser-produced plasmas within an ambient, highly magnetized background plasma at the UCLA Large Plasma Device facility. These plasmas form diamagnetic cavities in which a large fraction of the background field (600G) has been expelled. Fast (3ns) camera observations of this experiment recorded complicated structures, including coherent corrugated structures on the bubble surfaces. The data hint at the presence of turbulence in the interaction. In order to directly investigate the evolution of the magnetic field, we developed a novel diagnostic system composed of small (1-mm) 3-axis differential magnetic field probes, in conjunction with a vacuum ceramic motor system capable of sub-micron positioning accuracy. Using an ensemble of magnetic field data from fixed and movable probes, we calculate the cross-spectral function, from which the dominant modes and ultimately the dispersion relation of waves in this region may be deduced.

Neutron-Irradiated Samples as Test Materials for MPEX

DOE PAGES

Ellis, Ronald James; Rapp, Juergen

2015-10-09

Plasma Material Interaction (PMI) is a major concern in fusion reactor design and analysis. The Material-Plasma Exposure eXperiment (MPEX) will explore PMI under fusion reactor plasma conditions. Samples with accumulated displacements per atom (DPA) damage produced by fast neutron irradiations in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) will be studied in the MPEX facility. This paper presents assessments of the calculated induced radioactivity and resulting radiation dose rates of a variety of potential fusion reactor plasma-facing materials (such as tungsten). The scientific code packages MCNP and SCALE were used to simulate irradiation of themore » samples in HFIR including the generation and depletion of nuclides in the material and the subsequent composition, activity levels, gamma radiation fields, and resultant dose rates as a function of cooling time. A challenge of the MPEX project is to minimize the radioactive inventory in the preparation of the samples and the sample dose rates for inclusion in the MPEX facility.« less

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

NASA Astrophysics Data System (ADS)

Adli, E.; Lindstrøm, C. A.; Allen, J.; Clarke, C. I.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; Litos, M. D.; O'Shea, B.; Yakimenko, V.; An, W.; Clayton, C. E.; Marsh, K. A.; Mori, W. B.; Joshi, C.; Vafaei-Najafabadi, N.; Corde, S.; Lu, W.

2016-10-01

We report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. The attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam-plasma interactions in general and plasma wakefield accelerator technology in particular.

Theoretical and experimental studies of a planar inductive coupled rf plasma source as the driver in simulator facility (ISTAPHM) of interactions of waves with the edge plasma on tokamaks

NASA Astrophysics Data System (ADS)

Ghanei, V.; Nasrabadi, M. N.; Chin, O.-H.; Jayapalan, K. K.

2017-11-01

This research aims to design and build a planar inductive coupled RF plasma source device which is the driver of the simulator project (ISTAPHM) of the interactions between ICRF Antenna and Plasma on tokamak by using the AMPICP model. For this purpose, a theoretical derivation of the distribution of the RF magnetic field in the plasma-filled reactor chamber is presented. An experimental investigation of the field distributions is described and Langmuir measurements are developed numerically. A comparison of theory and experiment provides an evaluation of plasma parameters in the planar ICP reactor. The objective of this study is to characterize the plasma produced by the source alone. We present the results of the first analysis of the plasma characteristics (plasma density, electron temperature, electron-ion collision frequency, particle fluxes and their velocities, stochastic frequency, skin depth and electron energy distribution functions) as function of the operating parameters (injected power, neutral pressure and magnetic field) as measured with fixed and movable Langmuir probes. The plasma is currently produced only by the planar ICP. The exact goal of these experiments is that the produced plasma by external source can exist as a plasma representative of the edge of tokamaks.

Solar Radar Experiments

DTIC Science & Technology

1998-01-01

communications satellites and electric power grids. RELATED PROJECTS Studies with the HAARP radar facility being constructed in Alaska are conducted with...on wave-plasma interactions and also are assessing the possible use of HAARP as a solar radar. REFERENCES James, J. C., Radar studies of the sun, in

Progress in long scale length laser plasma interactions

NASA Astrophysics Data System (ADS)

Glenzer, S. H.; Arnold, P.; Bardsley, G.; Berger, R. L.; Bonanno, G.; Borger, T.; Bower, D. E.; Bowers, M.; Bryant, R.; Buckman, S.; Burkhart, S. C.; Campbell, K.; Chrisp, M. P.; Cohen, B. I.; Constantin, C.; Cooper, F.; Cox, J.; Dewald, E.; Divol, L.; Dixit, S.; Duncan, J.; Eder, D.; Edwards, J.; Erbert, G.; Felker, B.; Fornes, J.; Frieders, G.; Froula, D. H.; Gardner, S. D.; Gates, C.; Gonzalez, M.; Grace, S.; Gregori, G.; Greenwood, A.; Griffith, R.; Hall, T.; Hammel, B. A.; Haynam, C.; Heestand, G.; Henesian, M.; Hermes, G.; Hinkel, D.; Holder, J.; Holdner, F.; Holtmeier, G.; Hsing, W.; Huber, S.; James, T.; Johnson, S.; Jones, O. S.; Kalantar, D.; Kamperschroer, J. H.; Kauffman, R.; Kelleher, T.; Knight, J.; Kirkwood, R. K.; Kruer, W. L.; Labiak, W.; Landen, O. L.; Langdon, A. B.; Langer, S.; Latray, D.; Lee, A.; Lee, F. D.; Lund, D.; MacGowan, B.; Marshall, S.; McBride, J.; McCarville, T.; McGrew, L.; Mackinnon, A. J.; Mahavandi, S.; Manes, K.; Marshall, C.; Menapace, J.; Mertens, E.; Meezan, N.; Miller, G.; Montelongo, S.; Moody, J. D.; Moses, E.; Munro, D.; Murray, J.; Neumann, J.; Newton, M.; Ng, E.; Niemann, C.; Nikitin, A.; Opsahl, P.; Padilla, E.; Parham, T.; Parrish, G.; Petty, C.; Polk, M.; Powell, C.; Reinbachs, I.; Rekow, V.; Rinnert, R.; Riordan, B.; Rhodes, M.; Roberts, V.; Robey, H.; Ross, G.; Sailors, S.; Saunders, R.; Schmitt, M.; Schneider, M. B.; Shiromizu, S.; Spaeth, M.; Stephens, A.; Still, B.; Suter, L. J.; Tietbohl, G.; Tobin, M.; Tuck, J.; Van Wonterghem, B. M.; Vidal, R.; Voloshin, D.; Wallace, R.; Wegner, P.; Whitman, P.; Williams, E. A.; Williams, K.; Winward, K.; Work, K.; Young, B.; Young, P. E.; Zapata, P.; Bahr, R. E.; Seka, W.; Fernandez, J.; Montgomery, D.; Rose, H.

2004-12-01

The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3ω) with a total intensity of 2 × 1015 W cm-2. The targets were filled with 1 atm of CO2 producing up to 7 mm long homogeneously heated plasmas with densities of ne = 6 × 1020 cm-3 and temperatures of Te = 2 keV. The high energy in an NIF quad of beams of 16 kJ, illuminating the target from one direction, creates unique conditions for the study of laser-plasma interactions at scale lengths not previously accessible. The propagation through the large-scale plasma was measured with a gated x-ray imager that was filtered for 3.5 keV x-rays. These data indicate that the beams interact with the full length of this ignition-scale plasma during the last ~1 ns of the experiment. During that time, the full aperture measurements of the stimulated Brillouin scattering and stimulated Raman scattering show scattering into the four focusing lenses of 3% for the smallest length (~2 mm), increasing to 10-12% for ~7 mm. These results demonstrate the NIF experimental capabilities and further provide a benchmark for three-dimensional modelling of the laser-plasma interactions at ignition-size scale lengths.

Using the tritium plasma experiment to evaluate ITER PFC safety

NASA Astrophysics Data System (ADS)

Longhurst, Glen R.; Anderl, Robert A.; Bartlit, John R.; Causey, Rion A.; Haines, John R.

1993-06-01

The Tritium Plasma Experiment was assembled at Sandia National Laboratories, Livermore and is being moved to the Tritium Systems Test Assembly facility at Los Alamos National Laboratory to investigate interactions between dense plasmas at low energies and plasma-facing component materials. This apparatus has the unique capabilty of replicating plasma conditions in a tokamak divertor with particle flux densities of 2 × 1023 ions/m2.s and a plasma temperature of about 15 eV using a plasma that includes tritium. An experimental program has been initiated using the Tritium Plasma Experiment to examine safety issues related to tritium in plasma-facing components, particularly the ITER divertor. Those issues include tritium retention and release characteristics, tritium permeation rates and transient times to coolant streams, surface modification and erosion by the plasma, the effects of thermal loads and cycling, and particulate production. An industrial consortium led by McDonnell Douglas will design and fabricate the test fixtures.

On RF heating of inhomogeneous collisional plasma under ion-cyclotron resonance conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timofeev, A. V., E-mail: Timofeev-AV@nrcki.ru

2015-11-15

During ion-cyclotron resonance (ICR) heating of plasma by the magnetic beach method, as well as in some other versions of ICR heating, it is necessary to excite Alfvén oscillations. In this case, it is difficult to avoid the phenomenon of the Alfvén resonance, in which Alfvén oscillations transform into lower hybrid oscillations. The latter efficiently interact with electrons, due to which most of the deposited RF energy is spent on electron (rather than ion) heating. The Alfvén resonance takes place due to plasma inhomogeneity across the external magnetic field. Therefore, it could be expected that variations in the plasma densitymore » profile would substantially affect the efficiency of the interaction of RF fields with charged particles. However, the results obtained for different plasma density profiles proved to be nearly the same. In the present work, a plasma is considered the parameters of which correspond to those planned in future ICR plasma heating experiments on the PS-1 facility at the Kurchatov Institute. When analyzing the interaction of RF fields with charged particles, both the collisionless resonance interaction and the interaction caused by Coulomb collisions are taken into account, because, in those experiments, the Coulomb collision frequency will be comparable with the frequency of the heating field. Antennas used for ICR heating excite RF oscillations with a wide spectrum of wavenumbers along the magnetic field. After averaging over the spectrum, the absorbed RF energy calculated with allowance for collisions turns out to be close to that absorbed in collisionless plasma, the energy fraction absorbed by electrons being substantially larger than that absorbed by ions.« less

Validating Laser-Induced Birefringence Theory with Plasma Interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Cecilia; Cornell Univ., Ithaca, NY

2015-09-02

Intense laser beams crossing paths in plasma is theorized to induce birefringence in the medium, resulting from density and refractive index modulations that affect the polarization of incoming light. The goal of the associated experiment, conducted on Janus at Lawrence Livermore’s Jupiter Laser Facility, was to create a tunable laser-plasma waveplate to verify the relationship between dephasing angle and beam intensity, plasma density, plasma temperature, and interaction length. Interferometry analysis of the plasma channel was performed to obtain a density map and to constrain temperature measured from Thomson scattering. Various analysis techniques, including Fast Fourier transform (FFT) and two variationsmore » of fringe-counting, were tried because interferograms captured in this experiment contained unusual features such as fringe discontinuity at channel edges, saddle points, and islands. The chosen method is flexible, semi-automated, and uses a fringe tracking algorithm on a reduced image of pre-traced synthetic fringes. Ultimately, a maximum dephasing angle of 49.6° was achieved using a 1200 μm interaction length, and the experimental results appear to agree with predictions.« less

Simulation of plasma-surface interactions in a fusion reactor by means of QSPA plasma streams: recent results and prospects

NASA Astrophysics Data System (ADS)

Garkusha, I. E.; Aksenov, N. N.; Byrka, O. V.; Makhlaj, V. A.; Herashchenko, S. S.; Malykhin, S. V.; Petrov, Yu V.; Staltsov, V. V.; Surovitskiy, S. V.; Wirtz, M.; Linke, J.; Sadowski, M. J.; Skladnik-Sadowska, E.

2016-09-01

This paper is devoted to plasma-surface interaction issues at high heat-loads which are typical for fusion reactors. For the International Thermonuclear Experimental Reactor (ITER), which is now under construction, the knowledge of erosion processes and the behaviour of various constructional materials under extreme conditions is a very critical issue, which will determine a successful realization of the project. The most important plasma-surface interaction (PSI) effects in 3D geometry have been studied using a QSPA Kh-50 powerful quasi-stationary plasma accelerator. Mechanisms of the droplet and dust generation have been investigated in detail. It was found that the droplets emission from castellated surfaces has a threshold character and a cyclic nature. It begins only after a certain number of the irradiating plasma pulses when molten and shifted material is accumulated at the edges of the castellated structure. This new erosion mechanism, connected with the edge effects, results in an increase in the size of the emitted droplets (as compared with those emitted from a flat surface). This mechanism can even induce the ejection of sub-mm particles. A concept of a new-generation QSPA facility, the current status of this device maintenance, and prospects for further experiments are also presented.

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

DOE PAGES

Adli, Erik; Lindstrom, C. A.; Allen, J.; ...

2016-10-12

Here, we report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. Themore » attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam–plasma interactions in general and plasma wakefield accelerator technology in particular.« less

Long-range attraction of an ultrarelativistic electron beam by a column of neutral plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adli, Erik; Lindstrom, C. A.; Allen, J.

Here, we report on the experimental observation of the attraction of a beam of ultrarelativistic electrons towards a column of neutral plasma. In experiments performed at the FACET test facility at SLAC we observe that an electron beam moving parallel to a neutral plasma column, at an initial distance of many plasma column radii, is attracted into the column. Once the beam enters the plasma it drives a plasma wake similar to that of an electron beam entering the plasma column head-on. A simple analytical model is developed in order to capture the essential physics of the attractive force. Themore » attraction is further studied by 3D particle-in-cell numerical simulations. The results are an important step towards better understanding of particle beam–plasma interactions in general and plasma wakefield accelerator technology in particular.« less

Plasma interpenetration study on the Omega laser facility

NASA Astrophysics Data System (ADS)

Le Pape, Sebastien; Divol, Laurent; Ross, Steven; Wilks, Scott; Amendt, Peter; Berzak Hopkins, Laura; Huser, Gael; Moody, John; MacKinnon, Andy; Meezan, Nathan

2016-10-01

The Near Vacuum Campaign on the National Ignition Facility has sparked an interest on the nature of the gold/carbon interface at high velocity, high electron temperature, low-electron density. Indeed radiation-hydrodynamic simulations have been unable to accurately reproduce the experimental shape of the hot spot resulting from implosion driven in Near Vacuum Holhraum. The experimental data are suggesting that the inner beams are freely propagating to the waist of the hohlraum when simulations predict that a density ridge at the gold/carbon interface blocks the inner beams. The discrepancy between experimental data and simulation might be explained by the fluid description of the plasma interface in a rad-hydro code which is probably not valid in when two plasma at high velocity, high temperature are meeting. To test our assumption, we went to the Omega laser facility to study gold/carbon interface in the relevant regime. Time resolved images of the self-emission as well as Thomson scattering data will be presented. For the first time, a transition from a multifluid to a single fluid is observed as plasmas are interacting. This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

A plasma generator utilizing the high intensity ASTROMAG magnets

NASA Technical Reports Server (NTRS)

Sullivan, James D.; Post, R. S.; Lane, B. G.; Tarrh, J. M.

1986-01-01

The magnet configuration for the proposed particle astrophysics magnet facility (ASTROMAG) on the space station includes a cusp magnetic field with an intensity of a few tesla. With these large magnets (or others) located in the outer ionosphere, many quite interesting and unique plasma physics experiments become possible. First there are studies utilizing the magnet alone to examine the supersonic, sub-Alfvenic interaction with the ambient medium; the scale length for the magnet perturbation is approx. 20 m. The magnetic field geometry when combined with the Earth's and their relative motion will give rise to a host of plasma phenomena: ring nulls, x-points, ion-acoustic and lower-hybrid shocks, electron heating (possible shuttle glow without a surface) launching of Alfvenwaves, etc. Second, active experiments are possible for a controlled study of fundamental plasma phenomena. A controlled variable species plasma can be made by using an RF ion source; use of two soft iron rings placed about the line cusp would give an adequate resonance zone (ECH or ICH) and a confining volume suitable for gas efficiency. The emanating plasma can be used to study free expansion of plasma along and across field lines (polar wind), plasma flows around the space platform, turbulent mixing in the wake region, long wavelength spectrum of convecting modes, plasma-dust interactions, etc.

Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

NASA Astrophysics Data System (ADS)

Kim, Yong W.

Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

Overview of innovative PMI research on NSTX-U and associated PMI facilities at PPPL

DOE PAGES

M. Ono; Jaworski, M.; Kaita, R.; ...

2013-05-01

Developing a reactor compatible divertor and managing the associated plasma material interaction (PMI) has been identified as a high priority research area for magnetic confinement fusion. Accordingly on NSTX-U, the PMI research has received a strong emphasis. Moreover, with ˜15 MW of auxiliary heating power, NSTX-U will be able to test the PMI physics with the peak divertor plasma facing component (PFC) heat loads of up to 40-60 MW/m 2.

Results from colliding magnetized plasma jet experiments executed at the Trident laser facility

NASA Astrophysics Data System (ADS)

Manuel, M. J.-E.; Rasmus, A. M.; Kurnaz, C. C.; Klein, S. R.; Davis, J. S.; Drake, R. P.; Montgomery, D. S.; Hsu, S. C.; Adams, C. S.; Pollock, B. B.

2015-11-01

The interaction of high-velocity plasma flows in a background magnetic field has applications in pulsed-power and fusion schemes, as well as astrophysical environments, such as accretion systems and stellar mass ejections into the magnetosphere. Experiments recently executed at the Trident Laser Facility at the Los Alamos National Laboratory investigated the effects of an expanding aluminum plasma flow into a uniform 4.5-Tesla magnetic field created using a solenoid designed and manufactured at the University of Michigan. Opposing-target experiments demonstrate interesting collisional behavior between the two magnetized flows. Preliminary interferometry and Faraday rotation measurements will be presented and discussed. This work is funded by the U.S Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840. Support for this work was provided by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Astrophysical Observatory for NASA under contract NAS8-03060.

The WIND-HAARP Experiment: Initial Results of High Power Radiowave Interactions with Space Plasmas

DTIC Science & Technology

1997-11-10

Results from the first science experiment with the new HF Active Auroral Research Program ( HAARP ) facility in Alaska are reported. The initial...experiments involved transmission of high frequency waves from HAARP to the NASA/WIND satellite. The objective was to investigate the effects of space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, W. L.; Betti, R.; Hu, S. X.

Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2.

Electron Acceleration and Ionization Production in High-Power Heating Experiments at HAARP

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Pedersen, T.

2012-12-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60-80 km. Artificial ionization production is indicated by significant 427.8 nm emissions from the 1st negative band of N2+ and the appearance of transmitter-induced bottomside traces in ionosonde data during the periods of most intense optical emissions. However, the exact mechanisms producing the artificial plasmas remain to be determined. Yet the only existing theoretical models explain the development of artificial plasma as an ionizing wavefront moving downward due to ionization by electrons accelerated by HF-excited strong Langmuir turbulence (SLT) generated near the plasma resonance, where the pump frequency matches the plasma frequency. However, the observations suggest also the significance of interactions with upper hybrid and electron Bernstein waves near multiples of the electron gyrofrequency. We describe recent observations and discuss suitable acceleration mechanisms.

Magnetic flux pile-up and ion heating in a current sheet formed by colliding magnetized plasma flows

NASA Astrophysics Data System (ADS)

Suttle, L.; Hare, J.; Lebedev, S.; Ciardi, A.; Loureiro, N.; Niasse, N.; Burdiak, G.; Clayson, T.; Lane, T.; Robinson, T.; Smith, R.; Stuart, N.; Suzuki-Vidal, F.

2017-10-01

We present data from experiments carried out at the Magpie pulsed power facility, which show the detailed structure of the interaction of counter-streaming magnetized plasma flows. In our quasi-2D setup, continuous supersonic flows are produced with strong embedded magnetic fields of opposing directions. Their interaction leads to the formation of a dense and long-lasting current sheet, where we observe the pile-up of the magnetic flux at the sheet boundary, as well as the annihilation of field inside, accompanied by an increase in plasma temperature. Spatially resolved measurements with Faraday rotation polarimetry, B-dot probes, XUV imaging, Thomson scattering and laser interferometry diagnostics show the detailed distribution of the magnetic field and other plasma parameters throughout the system. This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/G001324/1, and by the U.S. Department of Energy (DOE) Awards No. DE-F03-02NA00057 and No. DE-SC-0001063.

X-ray spectroscopy diagnostics of a recombining plasma in laboratory astrophysics studies

NASA Astrophysics Data System (ADS)

Ryazantsev, S. N.; Skobelev, I. Yu.; Faenov, A. Ya.; Pikuz, T. A.; Grum-Grzhimailo, A. N.; Pikuz, S. A.

2015-12-01

The investigation of a recombining laser plasma is topical primarily because it can be used to simulate the interaction between plasma jets in astrophysical objects. It has been shown that the relative intensities of transitions of a resonance series of He-like multicharged ions can be used for the diagnostics of the recombining plasma. It has been found that the intensities of the indicated transitions for ions with the nuclear charge number Z n ~ 10 are sensitive to the plasma density in the range N e ~ 1016-1020 cm-3 at temperatures of 10-100 eV. The calculations performed for the F VIII ion have determined the parameters of plasma jets created at the ELFIE nanosecond laser facility (Ecole Polytechnique, France) in order to simulate astrophysical phenomena. The resulting universal calculation dependences can be used to diagnose different recombining plasmas containing helium-like fluorine ions.

Tritium Plasma Experiment Upgrade and Improvement of Surface Diagnostic Capabilities at STAR Facility for Enhancing Tritium and Nuclear PMI Sciences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shimada, M.; Taylor, C. N.; Pawelko, R. J.

2016-04-01

The Tritium Plasma Experiment (TPE) is a unique high-flux linear plasma device that can handle beryllium, tritium, and neutron-irradiated plasma facing materials, and is the only existing device dedicated to directly study tritium retention and permeation in neutron-irradiated materials with tritium [M. Shimada et.al., Rev. Sci. Instru. 82 (2011) 083503 and and M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008]. The plasma-material-interaction (PMI) determines a boundary condition for diffusing tritium into bulk PFCs, and the tritium PMI is crucial for enhancing fundamental sciences that dictate tritium fuel cycles and safety and are high importance to an FNSF and DEMO. Recentlymore » the TPE has undergone major upgrades in its electrical and control systems. New DC power supplies and a new control center enable remote plasma operations from outside of the contamination area for tritium, minimizing the possible exposure risk with tritium and beryllium. We discuss the electrical upgrade, enhanced operational safety, improved plasma performance, and development of optical spectrometer system. This upgrade not only improves operational safety of the worker, but also enhances plasma performance to better simulate extreme plasma-material conditions expected in ITER, Fusion Nuclear Science Facility (FNSF), and Demonstration reactor (DEMO). This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.« less

Design and installation of a ferromagnetic wall in tokamak geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, P. E., E-mail: peh2109@columbia.edu; Levesque, J. P.; Rivera, N.

Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective component test facility and DEMO power reactor. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these facilities. In order to study ferromagnetic effects in toroidal geometry, a ferritic wall upgrade was designed and installed in the High Beta Tokamak–Extended Pulse (HBT-EP). Several material options were investigated based on conductivity, magnetic permeability, vacuum compatibility, and other criteria, and the material of choice (high-cobalt steel) is characterized. Installation was accomplished quickly, with minimal impact on existing diagnostics andmore » overall machine performance, and initial results demonstrate the effects of the ferritic wall on plasma stability.« less

Investigation of Plasma Surface Interactions with the PISCES ELM Laser System

NASA Astrophysics Data System (ADS)

Umstadter, K. R.; Baldwin, M.; Hanna, J.; Doerner, R.; Lynch, T.; Palmer, T.; Tynan, G. R.

2007-11-01

When an ELM occurs in tokamaks, up to 30% of the pedestal energy can be deposited on the wall of the tokamak causing heating & material loss due to sublimation, evaporation and melt splashing of plasma facing components (PFCs) and expansion of the ejected material into the plasma. We have explored heat pulses using an electrical power circuit to draw electrons from the plasma to heat samples ohmically. This system is limited in power to ˜250kJ/m^2 at the minimum pulse width of 10ms and depletes the plasma column, complicating spectroscopy. We have completed calculations that indicate that a pulsed laser system can be used to simulate the heat pulse of ELMs. We are integrating laser systems into the existing PFC research program in PISCES, a laboratory facility capable of reproducing plasma-materials interactions expected during normal operation of large tokamaks. Two Nd:YAG lasers capable of delivering up to 50J of energy over various pulsewidths are used for the experiments. Laser heat pulse only, H+/D+ plasma only, and laser+plasma experiments were conducted and initial results indicate that metals behave very differently while exposed to plasma and simultaneous heat pulses. We will also discuss initial results for carbon PFCs and material transport into the plasma. Supported by US DoE grant DE-FG02-07ER-54912.

Liquid surfaces for fusion plasma facing components—A critical review. Part I: Physics and PSI

DOE PAGES

Nygren, R. E.; Tabares, F. L.

2016-12-01

This review of the potential of robust plasma facing components (PFCs) with liquid surfaces for applications in future D/T fusion device summarizes the critical issues for liquid surfaces and research being done worldwide in confinement facilities, and supporting R&D in plasma surface interactions. In the paper are a set of questions and related criteria by which we will judge the progress and readiness of liquid surface PFCs. Part-II (separate paper) will cover R&D on the technology-oriented aspects of liquid surfaces including the liquid surfaces as integrated first walls in tritium breeding blankets, tritium retention and recovery, and safety.

Modeling Laser-Plasma Interactions at Direct-Drive Ignition-Relevant Plasma Conditions at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Solodov, A. A.; Rosenberg, M. J.; Myatt, J. F.; Epstein, R.; Seka, W.; Hohenberger, M.; Short, R. W.; Shaw, J. G.; Regan, S. P.; Froula, D. H.; Radha, P. B.; Bates, J. W.; Schmitt, A. J.; Michel, P.; Moody, J. D.; Ralph, J. E.; Turnbull, D. P.; Barrios, M. A.

2016-10-01

Laser-plasma interaction instabilities, such as two-plasmon decay (TPD) and stimulated Raman scattering (SRS), can be detrimental for direct-drive inertial confinement fusion because of target preheat by generated high-energy electrons. The radiation-hydrodynamics code DRACO has been used to design planar-target experiments that generate plasma and interaction conditions relevant to direct-drive-ignition designs (IL 1015 W / cm 2 , Te > 3 KeV density gradient scale lengths of Ln 600 μm) . The hot-electron temperature of 40to50keV and the fraction of laser energy converted to hot electrons of 0.5to were inferred based on comparing the simulated and experimentally observed x-ray emission when the laser intensity at the quarter-critical surface increased from 6 to 15 ×1014 W / cm 2 . The measured SRS energy was sufficient to explain the observed total energy in hot electrons. Implications for ignition-scale direct-drive experiments and hot-electron preheat mitigation using mid- Z ablators will be discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Nuclear Reactions Studies in Laser-Plasmas at the forthcoming ELI-NP facilities

NASA Astrophysics Data System (ADS)

Lanzalone, G.; Muoio, A.; Altana, C.; Frassetto, M.; Malferrari, L.; Mascali, D.; Odorici, F.; Tudisco, S.; Gizzi, L. A.; Labate, L.; Puglia, S. M. R.; Trifirò, A.

2018-05-01

This work aim to prepare a program of studies on nuclear physics and astrophysics, which will be conducted at the new ELI-NP Laser facility, which actually is under construction in Bucharest, Romania. For the arguments treated, such activity has required also a multidisciplinary approach and knowledge in the fields of nuclear physics, astrophysics, laser and plasma physics join with also some competences on solid state physics related to the radiation detection. A part of this work has concerned to the experimental test, which have been performed in several laboratories and in order to study and increase the level of knowledge on the different parts of the project. In particular have been performed studies on the laser matter interaction at the ILIL laboratory of Pisa Italy and at the LENS laboratory in Catania, where (by using different experimental set-ups) has been investigated some key points concerning the production of the plasma stream. Test has been performed on several target configurations in terms of: composition, structure and size. All the work has been devoted to optimize the conditions of target in order to have the best performance on the production yields and on energies distribution of the inner plasma ions. A parallel activity has been performed in order to study the two main detectors, which will constitute the full detections system, which will be installed at the ELI-NP facility.

Laser Irradiated Foam Targets: Absorption and Radiative Properties

NASA Astrophysics Data System (ADS)

Salvadori, Martina; Luigi Andreoli, Pier; Cipriani, Mattia; Consoli, Fabrizio; Cristofari, Giuseppe; De Angelis, Riccardo; di Giorgio, Giorgio; Giulietti, Danilo; Ingenito, Francesco; Gus'kov, Sergey Yu.; Rupasov, Alexander A.

2018-01-01

An experimental campaign to characterize the laser radiation absorption of foam targets and the subsequent emission of radiation from the produced plasma was carried out in the ABC facility of the ENEA Research Center in Frascati (Rome). Different targets have been used: plastic in solid or foam state and aluminum targets. The activated different diagnostics allowed to evaluate the plasma temperature, the density distribution, the fast particle spectrum and the yield of the X-Ray radiation emitted by the plasma for the different targets. These results confirm the foam homogenization action on laser-plasma interaction, mainly attributable to the volume absorption of the laser radiation propagating in such structured materials. These results were compared with simulation absorption models of the laser propagating into a foam target.

The first target experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Landen, O. L.; Glenzer, S. H.; Froula, D. H.; Dewald, E. L.; Suter, L. J.; Schneider, M. B.; Hinkel, D. E.; Fernandez, J. C.; Kline, J. L.; Goldman, S. R.; Braun, D. G.; Celliers, P. M.; Moon, S. J.; Robey, H. S.; Lanier, N. E.; Glendinning, S. G.; Blue, B. E.; Wilde, B. H.; Jones, O. S.; Schein, J.; Divol, L.; Kalantar, D. H.; Campbell, K. M.; Holder, J. P.; McDonald, J. W.; Niemann, C.; MacKinnon, A. J.; Collins, G. W.; Bradley, D. K.; Eggert, J. H.; Hicks, D. G.; Gregori, G.; Kirkwood, R. K.; Young, B. K.; Foster, J. M.; Hansen, J. F.; Perry, T. S.; Munro, D. H.; Baldis, H. A.; Grim, G. P.; Heeter, R. F.; Hegelich, M. B.; Montgomery, D. S.; Rochau, G. A.; Olson, R. E.; Turner, R. E.; Workman, J. B.; Berger, R. L.; Cohen, B. I.; Kruer, W. L.; Langdon, A. B.; Langer, S. H.; Meezan, N. B.; Rose, H. A.; Still, C. H.; Williams, E. A.; Dodd, E. S.; Edwards, M. J.; Monteil, M.-C.; Stevenson, R. M.; Thomas, B. R.; Coker, R. F.; Magelssen, G. R.; Rosen, P. A.; Stry, P. E.; Woods, D.; Weber, S. V.; Young, P. E.; Alvarez, S.; Armstrong, G.; Bahr, R.; Bourgade, J.-L.; Bower, D.; Celeste, J.; Chrisp, M.; Compton, S.; Cox, J.; Constantin, C.; Costa, R.; Duncan, J.; Ellis, A.; Emig, J.; Gautier, C.; Greenwood, A.; Griffith, R.; Holdner, F.; Holtmeier, G.; Hargrove, D.; James, T.; Kamperschroer, J.; Kimbrough, J.; Landon, M.; Lee, F. D.; Malone, R.; May, M.; Montelongo, S.; Moody, J.; Ng, E.; Nikitin, A.; Pellinen, D.; Piston, K.; Poole, M.; Rekow, V.; Rhodes, M.; Shepherd, R.; Shiromizu, S.; Voloshin, D.; Warrick, A.; Watts, P.; Weber, F.; Young, P.; Arnold, P.; Atherton, L.; Bardsley, G.; Bonanno, R.; Borger, T.; Bowers, M.; Bryant, R.; Buckman, S.; Burkhart, S.; Cooper, F.; Dixit, S. N.; Erbert, G.; Eder, D. C.; Ehrlich, R. E.; Felker, B.; Fornes, J.; Frieders, G.; Gardner, S.; Gates, C.; Gonzalez, M.; Grace, S.; Hall, T.; Haynam, C. A.; Heestand, G.; Henesian, M. A.; Hermann, M.; Hermes, G.; Huber, S.; Jancaitis, K.; Johnson, S.; Kauffman, B.; Kelleher, T.; Kohut, T.; Koniges, A. E.; Labiak, T.; Latray, D.; Lee, A.; Lund, D.; Mahavandi, S.; Manes, K. R.; Marshall, C.; McBride, J.; McCarville, T.; McGrew, L.; Menapace, J.; Mertens, E.; Murray, J.; Neumann, J.; Newton, M.; Opsahl, P.; Padilla, E.; Parham, T.; Parrish, G.; Petty, C.; Polk, M.; Powell, C.; Reinbachs, I.; Rinnert, R.; Riordan, B.; Ross, G.; Robert, V.; Tobin, M.; Sailors, S.; Saunders, R.; Schmitt, M.; Shaw, M.; Singh, M.; Spaeth, M.; Stephens, A.; Tietbohl, G.; Tuck, J.; van Wonterghem, B. M.; Vidal, R.; Wegner, P. J.; Whitman, P.; Williams, K.; Winward, K.; Work, K.; Wallace, R.; Nobile, A.; Bono, M.; Day, B.; Elliott, J.; Hatch, D.; Louis, H.; Manzenares, R.; O'Brien, D.; Papin, P.; Pierce, T.; Rivera, G.; Ruppe, J.; Sandoval, D.; Schmidt, D.; Valdez, L.; Zapata, K.; MacGowan, B. J.; Eckart, M. J.; Hsing, W. W.; Springer, P. T.; Hammel, B. A.; Moses, E. I.; Miller, G. H.

2007-08-01

A first set of shock timing, laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and X-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1 9 ns pulses focused with various beam smoothing options. The experiments have demonstrated excellent agreement between measured and predicted laser-target coupling in foils and hohlraums, even when extended to a longer pulse regime unattainable at previous laser facilities, validated the predicted effects of beam smoothing on intense laser beam propagation in long scale-length plasmas and begun to test 3D codes by extending the study of laser driven hydrodynamic jets to 3D geometries.

Enhanced erosion of tungsten plasma-facing components subject to simultaneous heat pulses and deuterium plasma

NASA Astrophysics Data System (ADS)

Umstadter, K. R.; Doerner, R.; Tynan, G.

2009-04-01

When an ELM occurs in tokamaks, up to 30% of the pedestal energy can be deposited on the wall of the tokamak causing heating and material loss due to sublimation/evaporation and melt layer splashing of plasma-facing components (PFCs) and expansion of the ejected material into the plasma. A short-pulse laser system capable of reproducing the thermal load of an ELM heat pulse has been integrated into the existing PFC research program in PISCES, a laboratory facility capable of reproducing plasma-materials interactions expected during normal operation of large tokamaks. An Nd:YAG laser capable of delivering up to 1 J of energy over a 7 ns pulsewidth is used for the experiments. Laser heat pulse only, H +/D + plasma only, and laser plus plasma experiments were conducted and initial results indicate enhanced erosion of tungsten exposed to simultaneous plasma and heat pulses, as compared to exposure to separate plasma-only or heat pulse-only conditions.

3-D plasma boundary and plasma wall interaction research at UW-Madison

NASA Astrophysics Data System (ADS)

Schmitz, Oliver; Akerson, Adrian; Bader, Aaron; Barbui, Tullio; Effenberg, Florian; Flesch, Kurt; Frerichs, Heinke; Green, Jonathan; Hinson, Edward; Kremeyer, Thierry; Norval, Ryan; Stephey, Laurie; Waters, Ian; Winters, Victoria

2016-10-01

The necessity of considering 3-D effects on the plasma boundary and plasma wall interaction (PWI) in tokamaks, stellarators and reversed field pinches has been highlighted by abundant experimental and numerical results in the recent past. Prominent examples with 3-D boundary situations are numerous: ELM controlled H-modes by RMP fields in tokamaks, research on boundary plasmas and PWI in stellarators in general, quasi-helical states in RFPs, asymmetric fueling situations, and structural and wall elements which are not aligned with the magnetic guiding fields. A systematic approach is being taken at UW-Madison to establish a targeted experimental basis for identifying the most significant effects for plasma edge transport and resulting PWI in such 3-D plasma boundary situations. We deploy advanced 3-D modeling using the EMC3-EIRENE, ERO and MCI codes in combination with laboratory experiments at UW-Madison to investigate the relevance of 3-D effects in large scale devices with a concerted approach on DIII-D, NSTX-U, and Wendelstein 7-X. Highlights of experimental results from the on-site laboratory activities at UW-Madison and the large scale facilities are presented and interlinks will be discussed. This work was supported by US DOE DE-SC0013911, DE-SC00012315 and DE-SC00014210.

Studies of central interactions of Si ions at 14.5 x A GeV/c in Au and Cu

NASA Astrophysics Data System (ADS)

Eiseman, S. E.; Etkin, A.; Foley, K. J.; Hackenburg, R. W.; Longacre, R. S.; Love, W. A.; Morris, T. W.; Platner, E. D.; Saulys, A. C.; Lindenbaum, S. J.

Understanding the growth and saturation of parametric instabilities in laser-produced plasmas requires knowledge of the nonlinear properties of the instabilities and their interaction with each other. Nonlinear behavior of parametric instabilities, which are usually associated with unique optical features, were evidenced in numerous experiments on a variety of laser facilities. Four examples of nonlinear behavior in laser-produced plasmas are discussed: nonlinear stimulated Brillouin scattering spectra, suppression of stimulated Raman scattering by stimulated Brillouin scattering, the parametric decay instability and the onset of turbulence, and the transition to bursting behavior of the two-plasmon decay instability. Experiments are discussed that demonstrate the nonlinear effects which occur as a consequence.

Education Demonstration Equipment

NASA Astrophysics Data System (ADS)

Nagy, A.; Lee, R. L.

2005-10-01

Several GA Fusion Education Program plasma related demonstration items were developed this year. A 120 V ac powered electromagnetic coil shows eddy current levitation over an aluminum sheet and continuously changing magnetic force interactions using additional permanent magnets. A 300 V dc plasma device, with variable current capability and analog data ports, is used to develop plasma I/V plots. An on-demand (via push button) fully enclosed 24 in. Jacob's ladder provides air plasma and buoyancy effects. A low cost Mason jar vacuum chamber filled with inert gas shows pressure and gas species plasma characteristics when excited by a Tesla coil. These demonstration items are used in the Scientist-In-the-Classroom program, GA facility tours, and teacher seminars to present plasma to students and teachers. Three very popular Build-It workshops were held to enable teachers to build these items and take them back to their classroom.

To Demonstrate an Integrated Solution for Plasma-Material Interfaces Compatible with an Optimized Core Plasma

NASA Astrophysics Data System (ADS)

Goldston, Robert; Brooks, Jeffrey; Hubbard, Amanda; Leonard, Anthony; Lipschultz, Bruce; Maingi, Rajesh; Ulrickson, Michael; Whyte, Dennis

2009-11-01

The plasma facing components in a Demo reactor will face much more extreme boundary plasma conditions and operating requirements than any present or planned experiment. These include 1) Power density a factor of four or more greater than in ITER, 2) Continuous operation resulting in annual energy and particle throughput 100-200 times larger than ITER, 3) Elevated surface operating temperature for efficient electricity production, 4) Tritium fuel cycle control for safety and breeding requirements, and 5) Steady state plasma confinement and control. Consistent with ReNeW Thrust 12, design options are being explored for a new moderate-scale facility to assess core-edge interaction issues and solutions. Key desired features include high power density, sufficient pulse length and duty cycle, elevated wall temperature, steady-state control of an optimized core plasma, and flexibility in changing boundary components as well as access for comprehensive measurements.

Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kemp, Gregory Elijah

2013-01-01

Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the costmore » of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic laser-plasma interactions.« less

Enhanced Dispersion of TiO2 Nanoparticles in a TiO2/PEDOT:PSS Hybrid Nanocomposite via Plasma-Liquid Interactions

NASA Astrophysics Data System (ADS)

Liu, Yazi; Sun, Dan; Askari, Sadegh; Patel, Jenish; Macias-Montero, Manuel; Mitra, Somak; Zhang, Richao; Lin, Wen-Feng; Mariotti, Davide; Maguire, Paul

2015-10-01

A facile method to synthesize a TiO2/PEDOT:PSS hybrid nanocomposite material in aqueous solution through direct current (DC) plasma processing at atmospheric pressure and room temperature has been demonstrated. The dispersion of the TiO2 nanoparticles is enhanced and TiO2/polymer hybrid nanoparticles with a distinct core shell structure have been obtained. Increased electrical conductivity was observed for the plasma treated TiO2/PEDOT:PSS nanocomposite. The improvement in nanocomposite properties is due to the enhanced dispersion and stability in liquid polymer of microplasma treated TiO2 nanoparticles. Both plasma induced surface charge and nanoparticle surface termination with specific plasma chemical species are proposed to provide an enhanced barrier to nanoparticle agglomeration and promote nanoparticle-polymer binding.

Front surface structured targets for enhancing laser-plasma interactions

NASA Astrophysics Data System (ADS)

Snyder, Joseph; George, Kevin; Ji, Liangliang; Yalamanchili, Sasir; Simonoff, Ethan; Cochran, Ginevra; Daskalova, Rebecca; Poole, Patrick; Willis, Christopher; Lewis, Nathan; Schumacher, Douglass

2016-10-01

We present recent progress made using front surface structured interfaces for enhancing ultrashort, relativistic laser-plasma interactions. Structured targets can increase laser absorption and enhance ion acceleration through a number of mechanisms such as direct laser acceleration and laser guiding. We detail experimental results obtained at the Scarlet laser facility on hollow, micron-scale plasma channels for enhancing electron acceleration. These targets show a greater than three times enhancement in the electron cutoff energy as well as an increased slope temperature for the electron distribution when compared to a flat interface. Using three-dimensional particle-in-cell (PIC) simulations, we have modeled the interaction to give insight into the physical processes responsible for the enhancement. Furthermore, we have used PIC simulations to design structures that are more advantageous for ion acceleration. Such targets necessitate advanced target fabrication methods and we describe techniques used to manufacture optimized structures, including vapor-liquid-solid growth, cryogenic etching, and 3D printing using two-photon-polymerization. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-14-1-0085.

Electron Shock Ignition of Inertial Fusion Targets

DOE PAGES

Shang, W. L.; Betti, R.; Hu, S. X.; ...

2017-11-07

Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2.

Electron Shock Ignition of Inertial Fusion Targets

NASA Astrophysics Data System (ADS)

Shang, W. L.; Betti, R.; Hu, S. X.; Woo, K.; Hao, L.; Ren, C.; Christopherson, A. R.; Bose, A.; Theobald, W.

2017-11-01

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e 's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e 's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ˜1016 W /cm2 .

Electron Shock Ignition of Inertial Fusion Targets.

PubMed

Shang, W L; Betti, R; Hu, S X; Woo, K; Hao, L; Ren, C; Christopherson, A R; Bose, A; Theobald, W

2017-11-10

It is shown that inertial confinement fusion targets designed with low implosion velocities can be shock-ignited using laser-plasma interaction generated hot electrons (hot-e's) to obtain high energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e's which can be produced only at a large laser facility like the National Ignition Facility, with the laser-to-hot-e conversion efficiency greater than 10% at laser intensities ∼10^{16}  W/cm^{2}.

Laser-plasma extreme ultraviolet and soft X-ray sources based on a double stream gas puff target: interaction of the radiation pulses with matter

NASA Astrophysics Data System (ADS)

Bartnik, A.

2015-06-01

In this work a review of investigations concerning interaction of intense extreme ultraviolet (EUV) and soft X-ray (SXR) pulses with matter is presented. The investigations were performed using laser-produced plasma (LPP) EUV/SXR sources based on a double stream gas puff target. The sources are equipped with dedicated collectors allowing for efficient focusing of the EUV/SXR radiation pulses. Intense radiation in a wide spectral range, as well as a quasi-monochromatic radiation can be produced. In the paper different kinds of LPP EUV/SXR sources developed in the Institute of Optoelectronics, Military University of Technology are described. Radiation intensities delivered by the sources are sufficient for different kinds of interaction experiments including EUV/SXR induced ablation, surface treatment, EUV fluorescence or photoionized plasma creation. A brief review of the main results concerning this kind of experiments performed by author of the paper are presented. However, since the LPP sources cannot compete with large scale X-ray sources like synchrotrons, free electron lasers or high energy density plasma sources, it was indicated that some investigations not requiring extreme irradiation parameters can be performed using the small scale installations. Some results, especially concerning low temperature photoionized plasmas are very unique and could be hardly obtained using the large facilities.

Planar Laser-Plasma Interaction Experiments at Direct-Drive Ignition-Relevant Scale Lengths at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Rosenberg, M. J.; Solodov, A. A.; Seka, W.; Myatt, J. F.; Regan, S. P.; Hohenberger, M.; Epstein, R.; Froula, D. H.; Radha, P. B.; Michel, P. A.; Moody, J. D.; Masse, L.; Goyon, C.; Turnbull, D. P.; Barrios, M. A.; Bates, J. W.; Schmitt, A. J.

2016-10-01

The first experiments at the National Ignition Facility to probe laser-plasma interactions and the hot electron production at scale lengths relevant to direct-drive ignition are reported. The irradiation on one side of planar CH foils generated a plasma at the quarter-critical surface with predicted density scale lengths of Ln 600 μm, measured electron temperatures of Te 3.5 to 4.0 keV, and overlapped laser intensities of I 6 to 15 ×1014W/cm2. Optical emission from stimulated Raman scattering (SRS) and at ω/2 are correlated with the time-dependent hard x-ray signal. The fraction of laser energy converted to hot electrons increased from 0.5 % to 2.3 % as the laser intensity increased from 6 to 15 ×1014W/cm2, while the hot electron temperature was nearly constant around 40 to 50 keV. Only a sharp red-shifted feature is observed around ω/2, and both refracted and sidescattered SRS are detected, suggesting that multibeam SRS contributes to, and may even dominate, hot-electron production. These results imply a diminished presence of two-plasmon decay relative to SRS at these conditions, which has implications for hot-electron preheat mitigation strategies for direct-drive ignition. This work is supported by the DOE NNSA under Award Number DE-NA0001944.

Design of an Experiment to Observe Laser-Plasma Interactions on NIKE

NASA Astrophysics Data System (ADS)

Phillips, L.; Weaver, J.; Manheimer, W.; Zalesak, S.; Schmitt, A.; Fyfe, D.; Afeyan, B.; Charbonneau-Lefort, M.

2007-11-01

Recent proposed designs (Obenschain et al., Phys. Plasmas 13 056320 (2006)) for direct-drive ICF targets for energy applications involve high implosion velocities combined with higher laser irradiances. The use of high irradiances increases the likelihood of deleterious laser plasma instabilities (LPI) that may lead, for example, to the generation of fast electrons. The proposed use of a 248 nm KrF laser to drive these targets is expected to minimize LPI; this is being studied by experiments at NRL's NIKE facility. We used a modification of the FAST code that models laser pulses with arbitrary spatial and temporal profiles to assist in designing these experiments. The goal is to design targets and pulseshapes to create plasma conditions that will produce sufficient growth of LPI to be observable on NIKE. Using, for example, a cryogenic DT target that is heated by a brief pulse and allowed to expand freely before interacting with a second, high-intensity pulse, allows the development of long scalelengths at low electron temperatures and leads to a predicted 20-efold growth in two-plasmon amplitude.

Studies of supersonic, radiative plasma jet interaction with gases at the Prague Asterix Laser System facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicolaie, Ph.; Stenz, C.; Tikhonchuk, V.

2008-08-15

The interaction of laser driven jets with gas puffs at various pressures is investigated experimentally and is analyzed by means of numerical tools. In the experiment, a combination of two complementary diagnostics allowed to characterize the main structures in the interaction zone. By changing the gas composition and its density, the plasma cooling time can be controlled and one can pass from a quasiadiabatic outflow to a strongly radiation cooling jet. This tuning yields hydrodynamic structures very similar to those seen in astrophysical objects; the bow shock propagating through the gas, the shocked materials, the contact discontinuity, and the Machmore » disk. From a dimensional analysis, a scaling is made between both systems and shows the study relevance for the jet velocity, the Mach number, the jet-gas density ratio, and the dissipative processes. The use of a two-dimensional radiation hydrodynamic code, confirms the previous analysis and provides detailed structure of the interaction zone and energy repartition between jet and surrounding gases.« less

Simultaneous Multi-angle Observations of Strong Langmuir Turbulence at HAARP

NASA Astrophysics Data System (ADS)

Watanabe, Naomi; Golkowski, Mark; Sheerin, James P.; Watkins, Brenton J.

2015-10-01

We report results from a recent series of experiments employing the HF transmitter of the High Frequency Active Auroral Research Program (HAARP) to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. The Modular UHF Ionospheric Radar (MUIR) located at the HAARP facility is used as the primary diagnostic. Short pulse, low duty cycle experiments are used to avoid generation of artificial field-aligned irregularities and isolate ponderomotive plasma turbulence effects. The HF pump frequency is close to the 3rd gyro-harmonic frequency and the HF pointing angle and MUIR look angle are between the HF Spitze angle and Magnetic Zenith angle. Plasma line spectra measured simultaneously in different spots of the interaction region display differences dependent on the aspect angle of the HF pump beam in the boresight direction and the pointing angle of the MUIR diagnostic radar. Outshifted Plasma Lines, cascade, collapse, coexistence, spectra are observed in agreement with existing theory and simulation results of Strong Langmuir Turbulence in ionospheric interaction experiments. It is found that SLT at HAARP is most readily observed at a HF pointing angle of 11° and UHF observation angle of 15°, which is consistent with the magnetic zenith effect as documented in previous works and optimal orientation of the refracted HF electric field vector.

Recent Advances in Narrowband Stimulated Electromagnetic Emission NSEE Investigations at HAARP and EISCAT

NASA Astrophysics Data System (ADS)

Scales, Wayne

2016-07-01

Investigation of stimulated radiation, commonly known as Stimulated Electromagnetic Emissions (SEE), produced by the interaction of high-power, High Frequency HF radiowaves with the ionospheric plasma has been a vibrant area of research since the early 1980's. Substantial diagnostic information about ionospheric plasma characteristics, dynamics, and turbulence can be obtained from the frequency spectrum of the stimulated radiation. During the past several decades, so-called wideband SEE (WSEE) which exists in a frequency band of ±100 KHz or so of the transmit wave frequency (which is several MHz) has been investigated relatively thoroughly. Upgrades both in transmitter power and diagnostic receiver frequency sensitivity at major ionosphere interaction facilities (i.e. HAARP and EISCAT) have allowed new breakthroughs in the ability to study a plethora of processes associated with the ionospheric plasma during these active experiments. A primary advance is in observations of so-called narrowband SEE (NSEE) which exists roughly within ±1 kHz of the transmit wave frequency. NSEE investigation has opened the door for a potentially powerful tool for aeronomy investigations as well. An overview of several important new results associated with NSEE are discussed in this presentation, including observations, theory, computational modeling, as well as implications to new diagnostics of space plasma physics occurring during ionospheric interaction experiments.

Laboratory Plasma Source as an MHD Model for Astrophysical Jets

NASA Technical Reports Server (NTRS)

Mayo, Robert M.

1997-01-01

The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to astrophysical jet observation. There exists overwhelming similarity among these flows that has already produced some fascinating results and is expected to continue a high pay off in future flow similarity studies.

Characterizing the Performance of the Princeton Advanced Test Stand Ion Source

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2012-10-01

The Princeton Advanced Test Stand (PATS) is a compact experimental facility for studying the physics of intense beam-plasma interactions relevant to the Neutralized Drift Compression Experiment - II (NDCX-II). The PATS facility consists of a multicusp RF ion source mounted on a 2 m-long vacuum chamber with numerous ports for diagnostic access. Ar+ beams are extracted from the source plasma with three-electrode (accel-decel) extraction optics. The RF power and extraction voltage (30 - 100 kV) are pulsed to produce 100 μsec duration beams at 0.5 Hz with excellent shot-to-shot repeatability. Diagnostics include Faraday cups, a double-slit emittance scanner, and scintillator imaging. This work reports measurements of beam parameters for a range of beam energies (30 - 50 keV) and currents to characterize the behavior of the ion source and extraction optics. Emittance scanner data is used to calculate the beam trace-space distribution and corresponding transverse emittance. If the plasma density is changing during a beam pulse, time-resolved emittance scanner data has been taken to study the corresponding evolution of the beam trace-space distribution.

Influence of Ionization and Beam Quality on Interaction of TW-Peak CO2 Laser with Hydrogen Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samulyak, Roman

3D numerical simulations of the interaction of a powerful CO2 laser with hydrogen jets demonstrating the role of ionization and laser beam quality are presented. Simulations are performed in support of the plasma wakefield accelerator experiments being conducted at the BNL Accelerator Test Facility (ATF). The CO2 laser at BNL ATF has several potential advantages for laser wakefield acceleration compared to widely used solid-state lasers. SPACE, a parallel relativistic Particle-in-Cell code, developed at SBU and BNL, has been used in these studies. A novelty of the code is its set of efficient atomic physics algorithms that compute ionization and recombinationmore » rates on the grid and transfer them to particles. The primary goal of the initial BNL experiments was to characterize the plasma density by measuring the sidebands in the spectrum of the probe laser. Simulations, that resolve hydrogen ionization and laser spectra, help explain several trends that were observed in the experiments.« less

Modeling Electrothermal Plasma with Boundary Layer Effects

NASA Astrophysics Data System (ADS)

AlMousa, Nouf Mousa A.

Electrothermal plasma sources produce high-density (1023-10 28 /m3) and high temperature (1-5 eV) plasmas that are of interest for a variety of applications such as hypervelocity launch devices, fusion reactor pellet injectors, and pulsed thrusters for small satellites. Also, the high heat flux (up to 100 GW/m2) and high pressure (100s MPa) of electrothermal (ET) plasmas allow for the use of such facilities as a source of high heat flux to simulate off-normal events in Tokamak fusion reactors. Off-normal events like disruptions, thermal and current quenches, are the perfect recipes for damage of plasma facing components (PFC). Successful operation of a fusion reactor requires comprehensive understanding of material erosion behavior. The extremely high heat fluxes deposited in PFCs melt and evaporate or directly sublime the exposed surfaces, which results in a thick vapor/melt boundary layer adjacent to the solid wall structure. The accumulating boundary layers provide a self-protecting nature by attenuating the radiant energy transport to the PFCs. The ultimate goal of this study is to develop a reliable tool to adequately simulate the effect of the boundary layers on the formation and flow of the energetic ET plasma and its impact on exposed surfaces erosion under disruption like conditions. This dissertation is a series of published journals/conferences papers. The first paper verified the existence of the vapor shield that evolved at the boundary layer under the typical operational conditions of the NC State University ET plasma facilities PIPE and SIRENS. Upon the verification of the vapor shield, the second paper proposed novel model to simulate the evolution of the boundary layer and its effectiveness in providing a self-protecting nature for the exposed plasma facing surfaces. The developed models simulate the radiant heat flux attenuation through an optically thick boundary layer. The models were validated by comparing the simulation results to experimental data taken from the ET plasma facilities. Upon validation of the boundary layer models, computational experiments were conducted with the purpose of evaluation the PFCs' erosion during plasma disruption in Tokamak fusion reactors. Erosion of a set of selected low-Z and high-Z materials were analyzed and discussed. For metallic plasma facing materials under the impact of hard and long time-scale disruption events, melting and melt-layer splashing become dominate erosion mechanisms during plasma-material interaction. In order to realistically assess the erosion of the metallic fusion reactor components, the fourth paper accounts for the various mechanisms by which material evolved from PFCs due to melting and vaporization, with a developed melting and splattering/splashing model incorporated in the ET plasma code. Also, the shielding effect associated with melt-layer and vapor-layer is investigated. The quantitative results of material erosion with the boundary layer effects including a vapor layer, melt layer and splashing effects is a new model and an important step towards achieving a better understanding of plasma-material interactions under exposure to such high heat flux conditions.

Semiconductor and thermoluminescent dosimetry of pulsed soft X ray plasma sources.

PubMed

Krása, J; Cejnarová, A; Juha, L; Ryć, L; Scholz, M; Kubes, P

2002-01-01

A multichannel detection system having a dynamic range of approximately 1 x 10(-9) Gy --20 Gy was developed with the use of commercially produced Si-photodiodes and TLDs for accurate measurement of X ray energy emitted from plasma-focus facility and from laser-produced plasmas. The proof of linearity of the employed detectors accomplished by a comparison of their responses to a broad band spectrum of X rays emitted from plasmas, is reported. It is demonstrated that TLDs irradiated with no protective filter show an incorrect response due to overloading in the sub-keV range and repopulation of dosimetric peaks induced by the UV radiation. The measurement of the power of undesirable secondary X ray sources driven by the primary plasma inside the interaction chamber was performed on the basis of analysis of space dependence of X ray intensity with respect to the assumed r(-2) decrease in the intensity far away from the plasma.

Feasibility Study for a Plasma Dynamo Facility to Investigate Fundamental Processes in Plasma Astrophysics. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forest, Cary B.

The scientific equipment purchased on this grant was used on the Plasma Dynamo Prototype Experiment as part of Professor Forest's feasibility study for determining if it would be worthwhile to propose building a larger plasma physics experiment to investigate various fundamental processes in plasma astrophysics. The initial research on the Plasma Dynamo Prototype Experiment was successful so Professor Forest and Professor Ellen Zweibel at UW-Madison submitted an NSF Major Research Instrumentation proposal titled "ARRA MRI: Development of a Plasma Dynamo Facility for Experimental Investigations of Fundamental Processes in Plasma Astrophysics." They received funding for this project and the Plasma Dynamomore » Facility also known as the "Madison Plasma Dynamo Experiment" was constructed. This experiment achieved its first plasma in the fall of 2012 and U.S. Dept. of Energy Grant No. DE-SC0008709 "Experimental Studies of Plasma Dynamos," now supports the research.« less

Making of the NSTX Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

C. Neumeyer; M. Ono; S.M. Kaye

1999-11-01

The NSTX (National Spherical Torus Experiment) facility located at Princeton Plasma Physics Laboratory is the newest national fusion science experimental facility for the restructured US Fusion Energy Science Program. The NSTX project was approved in FY 97 as the first proof-of-principle national fusion facility dedicated to the spherical torus research. On Feb. 15, 1999, the first plasma was achieved 10 weeks ahead of schedule. The project was completed on budget and with an outstanding safety record. This paper gives an overview of the NSTX facility construction and the initial plasma operations.

Study of Plasma Flow Modes in Imploding Nested Arrays

NASA Astrophysics Data System (ADS)

Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

2018-02-01

Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r < V A ) and super-Alfvénic ( V r > V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

Laboratory simulations of astrophysical jets: results from experiments at the PF-3, PF-1000U, and KPF-4 facilities

NASA Astrophysics Data System (ADS)

Krauz, V. I.; Myalton, V. V.; Vinogradov, V. P.; Velikhov, E. P.; Ananyev, S. S.; Dan'ko, S. A.; Kalinin, Yu G.; Kharrasov, A. M.; Vinogradova, Yu V.; Mitrofanov, K. N.; Paduch, M.; Miklaszewski, R.; Zielinska, E.; Skladnik-Sadowska, E.; Sadowski, M. J.; Kwiatkowski, R.; Tomaszewski, K.; Vojtenko, D. A.

2017-10-01

Results are presented from laboratory simulations of plasma jets emitted by young stellar objects carried out at the plasma focus facilities. The experiments were performed at three facilities: the PF-3, PF-1000U and KPF-4. The operation modes were realized enabling the formation of narrow plasma jets which can propagate over long distances. The main parameters of plasma jets and background plasma were determined. In order to control the ratio of a jet density to that of background plasma, some special operation modes with pulsed injection of the working gas were used.

Design of a high particle flux hydrogen helicon plasma source for used in plasma materials interaction studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goulding, R. H.; Chen, G.; Meitner, S.

2009-11-26

Existing linear plasma materials interaction (PMI) facilities all use plasma sources with internal electrodes. An rf-based helicon source is of interest because high plasma densities can be generated with no internal electrodes, allowing true steady state operation with minimal impurity generation. Work has begun at Oak Ridge National Laboratory (ORNL) to develop a large (15 cm) diameter helicon source producing hydrogen plasmas with parameters suitable for use in a linear PMI device: n{sub e}{>=}10{sup 19} m{sup -3}, T{sub e} = 4-10 eV, particle flux {gamma}{sub p}>10{sup 23}m{sup -3} s{sup -1}, and magnetic field strength |B| up to 1 T inmore » the source region. The device, whose design is based on a previous hydrogen helicon source operated at ORNL[1], will operate at rf frequencies in the range 10-26 MHz, and power levels up to {approx}100 kW. Limitations in cooling will prevent operation for pulses longer than several seconds, but a major goal will be the measurement of power deposition on device structures so that a later steady state version can be designed. The device design, the diagnostics to be used, and results of rf modeling of the device will be discussed. These include calculations of plasma loading, resulting currents and voltages in antenna structures and the matching network, power deposition profiles, and the effect of high |B| operation on power absorption.« less

Bridging the PSI Knowledge Gap: A Multi-Scale Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wirth, Brian D.

2015-01-08

Plasma-surface interactions (PSI) pose an immense scientific hurdle in magnetic confinement fusion and our present understanding of PSI in confinement environments is highly inadequate; indeed, a recent Fusion Energy Sciences Advisory Committee report found that 4 out of the 5 top five fusion knowledge gaps were related to PSI. The time is appropriate to develop a concentrated and synergistic science effort that would expand, exploit and integrate the wealth of laboratory ion-beam and plasma research, as well as exciting new computational tools, towards the goal of bridging the PSI knowledge gap. This effort would broadly advance plasma and material sciences,more » while providing critical knowledge towards progress in fusion PSI. This project involves the development of a Science Center focused on a new approach to PSI science; an approach that both exploits access to state-of-the-art PSI experiments and modeling, as well as confinement devices. The organizing principle is to develop synergistic experimental and modeling tools that treat the truly coupled multi-scale aspect of the PSI issues in confinement devices. This is motivated by the simple observation that while typical lab experiments and models allow independent manipulation of controlling variables, the confinement PSI environment is essentially self-determined with few outside controls. This means that processes that may be treated independently in laboratory experiments, because they involve vastly different physical and time scales, will now affect one another in the confinement environment. Also, lab experiments cannot simultaneously match all exposure conditions found in confinement devices typically forcing a linear extrapolation of lab results. At the same time programmatic limitations prevent confinement experiments alone from answering many key PSI questions. The resolution to this problem is to usefully exploit access to PSI science in lab devices, while retooling our thinking from a linear and de-coupled extrapolation to a multi-scale, coupled approach. The PSI Plasma Center consisted of three equal co-centers; one located at the MIT Plasma Science and Fusion Center, one at UC San Diego Center for Energy Research and one at the UC Berkeley Department of Nuclear Engineering, which moved to the University of Tennessee, Knoxville (UTK) with Professor Brian Wirth in July 2010. The Center had three co-directors: Prof. Dennis Whyte led the MIT co-center, the UCSD co-center was led by Dr. Russell Doerner, and Prof. Brian Wirth led the UCB/UTK center. The directors have extensive experience in PSI and material research, and have been internationally recognized in the magnetic fusion, materials and plasma research fields. The co-centers feature keystone PSI experimental and modeling facilities dedicated to PSI science: the DIONISOS/CLASS facility at MIT, the PISCES facility at UCSD, and the state-of-the-art numerical modeling capabilities at UCB/UTK. A collaborative partner in the center is Sandia National Laboratory at Livermore (SNL/CA), which has extensive capabilities with low energy ion beams and surface diagnostics, as well as supporting plasma facilities, including the Tritium Plasma Experiment, all of which significantly augment the Center. Interpretive, continuum material models are available through SNL/CA, UCSD and MIT. The participating institutions of MIT, UCSD, UCB/UTK, SNL/CA and LLNL brought a formidable array of experimental tools and personnel abilities into the PSI Plasma Center. Our work has focused on modeling activities associated with plasma surface interactions that are involved in effects of He and H plasma bombardment on tungsten surfaces. This involved performing computational material modeling of the surface evolution during plasma bombardment using molecular dynamics modeling. The principal outcomes of the research efforts within the combined experimental – modeling PSI center are to provide a knowledgebase of the mechanisms of surface degradation, and the influence of the surface on plasma conditions.« less

Experimental Simulation of the Interaction of Biased Solar Arrays with the Space Plasma

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Robinson, R. S.

1981-01-01

The phenomenon of unexpectedly large leakage currents collected by small exposed areas of high voltage solar arrays operating in a plasma environment was investigated. Polyimide (Kapton) was the insulating material used in all tests. Both positive bias (electron collection) and negative bias (ion collection) tests were performed. A mode change in the electron collection mechanism was associated with a glow discharge process and was found to be related to the neutral background density. Results indicate that the glow discharge collection mode does not occur in a space environment where the background density is considerably lower than that of the vacuum facility used.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bondarenko, A. S., E-mail: AntonBondarenko@ymail.com; Schaeffer, D. B.; Everson, E. T.

The collision-less transfer of momentum and energy from explosive debris plasma to magnetized background plasma is a salient feature of various astrophysical and space environments. While much theoretical and computational work has investigated collision-less coupling mechanisms and relevant parameters, an experimental validation of the results demands the measurement of the complex, collective electric fields associated with debris-background plasma interaction. Emission spectroscopy offers a non-interfering diagnostic of electric fields via the Stark effect. A unique experiment at the University of California, Los Angeles, that combines the Large Plasma Device (LAPD) and the Phoenix laser facility has investigated the marginally super-Alfvénic, quasi-perpendicularmore » expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via emission spectroscopy. Spectral profiles of the He II 468.6 nm line measured at the maximum extent of the diamagnetic cavity are observed to intensify, broaden, and develop equally spaced modulations in response to the explosive C debris, indicative of an energetic electron population and strong oscillatory electric fields. The profiles are analyzed via time-dependent Stark effect models corresponding to single-mode and multi-mode monochromatic (single frequency) electric fields, yielding temporally resolved magnitudes and frequencies. The proximity of the measured frequencies to the expected electron plasma frequency suggests the development of the electron beam-plasma instability, and a simple saturation model demonstrates that the measured magnitudes are feasible provided that a sufficiently fast electron population is generated during C debris–He background interaction. Potential sources of the fast electrons, which likely correspond to collision-less coupling mechanisms, are briefly considered.« less

Laser-direct-drive program: Promise, challenge, and path forward

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, E. M.; Goncharov, V. N.; Sangster, T. C.

Along with laser-indirect (x-ray)-drive and magnetic-drive target concepts, laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion. In the United States, a national program has been established to demonstrate and understand the physics of laser direct drive. The program utilizes the Omega Laser Facility to conduct implosion and coupling physics at the nominally 30-kJ scale and laser–plasma interaction and coupling physics at the MJ scale at the National Ignition Facility. This paper will discuss the motivation and challenges for laser direct drive and the broad-based program presently underway in the United States.

Laser-direct-drive program: Promise, challenge, and path forward

DOE PAGES

Campbell, E. M.; Goncharov, V. N.; Sangster, T. C.; ...

2017-03-19

Along with laser-indirect (x-ray)-drive and magnetic-drive target concepts, laser direct drive is a viable approach to achieving ignition and gain with inertial confinement fusion. In the United States, a national program has been established to demonstrate and understand the physics of laser direct drive. The program utilizes the Omega Laser Facility to conduct implosion and coupling physics at the nominally 30-kJ scale and laser–plasma interaction and coupling physics at the MJ scale at the National Ignition Facility. This paper will discuss the motivation and challenges for laser direct drive and the broad-based program presently underway in the United States.

Ion beam generated modes in the lower hybrid frequency range in a laboratory magnetoplasma

NASA Astrophysics Data System (ADS)

Van Compernolle, B.; Tripathi, S.; Gekelman, W. N.; Colestock, P. L.; Pribyl, P.

2012-12-01

The generation of waves by ion ring distributions is of great importance in many instances in space plasmas. They occur naturally in the magnetosphere through the interaction with substorms, or they can be man-made in ionospheric experiments by photo-ionization of neutral atoms injected perpendicular to the earth's magnetic field. The interaction of a fast ion beam with a low β plasma has been studied in the laboratory. Experiments were performed at the LArge Plasma Device (LAPD) at UCLA. The experiments were done in a Helium plasma (n ≃ 1012 \\ cm-3, B0 = 1000 G - 1800 G, fpe}/f{ce ≃ 1 - 5, Te = 0.25\\ eV, vte ≤ vA). The ion beam \\cite{Tripathi_ionbeam} is a Helium beam with energies ranging from 5 keV to 18 keV. The fast ion velocity is on the order of the Alfvén velocity. The beam is injected from the end of the machine, and spirals down the linear device. Waves were observed below fci in the shear Alfvén wave regime, and in a broad spectrum above fci in the lower hybrid frequency range, the focus of this paper. The wave spectra have distinct peaks close to ion cyclotron harmonics, extending out to the 100th harmonic in some cases. The wave generation was studied for various magnetic fields and background plasma densities, as well as for different beam energies and pitch angles. The waves were measured with 3-axis electric and magnetic probes. Detailed measurements of the perpendicular mode structure will be shown. Langmuir probes were used to measure density and temperature evolution due to the beam-plasma interaction. Retarding field energy analyzers captured the ion beam profiles. The work was performed at the LArge Plasma Device at the Basic Plasma Science Facility (BaPSF) at UCLA, funded by DOE/NSF.

Laboratory Studies of the Nonlinear Interactions of Kink-Unstable Flux Ropes and Shear Alfvén Waves

NASA Astrophysics Data System (ADS)

Vincena, S. T.; Tripathi, S.; Gekelman, W. N.; DeHaas, T.; Pribyl, P.

2017-12-01

Magnetic flux ropes and shear Alfvén waves occur simultaneously in plasmas ranging from solar prominences, to the solar wind, to planetary magnetospheres. If the flux ropes evolve to become unstable to the kink mode, interactions between the kink oscillations and the shear waves can arise, and may even lead to nonlinear phenomena. Experiments aimed at elucidating such interactions are performed in the upgraded Large Plasma Device at UCLA. Flux ropes are generated using a 20 cm x 20 cm LaB6 cathode-anode discharge (with L = 18 m and β ˜ 0.1.) The ropes are embedded in a larger, otherwise current-free, cylindrical (r = 30cm) ambient plasma produced by a second cathode. Shear Alfvén waves are launched using externally fed antennas having three separate polarizations (azimuthal mode numbers.) The counter-propagating, kink-unstable oscillations and driven shear waves are observed to nonlinearly generate sidebands about the higher, shear wave frequency (evident in power spectra) via three-wave coupling. This is demonstrated though bi-coherence calculations and k-matching. With a fixed kink-mode polarization, a total of six daughter wave patterns are presented. Energy flow is shown to proceed from larger to smaller perpendicular wavelengths. Future work will focus on increasing the plasma beta and wave amplitudes in the quest to observe an evolution to a turbulent state. Work is performed at the US Basic Plasma Science Facility, which is supported by the US Department of Energy and the National Science Foundation.

Anomalous neutron yield in indirect-drive inertial-confinement-fusion due to the formation of collisionless shocks in the corona

NASA Astrophysics Data System (ADS)

Zhang, Wen-Shuai; Cai, Hong-Bo; Shan, Lian-Qiang; Zhang, Hua-Sen; Gu, Yu-Qiu; Zhu, Shao-Ping

2017-06-01

Observations of anomalous neutron yield in the indirect-drive inertial confinement fusion implosion experiments conducted at SG-III prototype and SG-II upgrade laser facilities are interpreted. The anomalous mechanism results in a neutron yield which is 100-times higher than that predicted by 1D radiation-hydrodynamic simulations. 2D radiation-hydrodynamic simulations show that the supersonic, radially directed gold (Au) plasma jets arising from the laser-hohlraum interactions can collide with the carbon-deuterium (CD) corona plasma of the compressed pellet. It is found that in the interaction front of the high-Z jet with the low-Z corona, with low density  ˜{{10}20}~\\text{c}{{\\text{m}}-3} and high temperature  ˜keV, kinetic effects become important. Particle-in-cell simulations indicate that an electrostatic shock wave can be driven when the high-temperature Au jet expands into the low-temperature CD corona. Deuterium ions with an amount of  ˜1015 can be accelerated to  ˜25 keV by the collisionless shock wave, thus causing efficient neutron productions though the beam-target method by stopping these energetic ions in the corona. The evaluated neutron yield is consistent with the experiments conducted at SG laser facilities.

Plasma photonics in ICF & HED conditions

NASA Astrophysics Data System (ADS)

Michel, Pierre; Turnbull, David; Divol, Laurent; Pollock, Bradley; Chen, Cecilia Y.; Tubman, Eleanor; Goyon, Clement S.; Moody, John D.

2015-11-01

Interactions between multiple high-energy laser beams and plasma can be used to imprint refractive micro-structures in plasmas via the lasers' ponderomotive force. For example, Inertial confinement fusion (ICF) experiments at the National Ignition Facility already rely on the use of plasma gratings to redirect laser light inside an ICF target and tune the symmetry of the imploded core. More recently, we proposed new concepts of plasma polarizer and waveplate, based on two-wave mixing schemes and laser-induced plasma birefringence. In this talk, we will present new experimental results showing the first demonstration of a fully tunable plasma waveplate, which achieved near-perfect circular laser polarization. We will discuss further prospects for novel ``plasma photonics'' concepts based on two- and four-wave mixing, such as optical switches, bandpass filters, anti-reflection blockers etc. These might find applications in ICF and HED experiments by allowing to manipulate the lasers directly in-situ (i.e. inside the targets), as well as for the design of high power laser systems. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Space Plasma Testing of High-Voltage Thin-Film Solar Arrays with Protective Coatings

NASA Technical Reports Server (NTRS)

Tlomak, Pawel; Hausgen, Paul E.; Merrill, John; Senft, Donna; Piszczor, Michael F., Jr.

2007-01-01

This paper gives an overview of the space plasma test program for thin-film photovoltaics (TFPV) technologies developed at the Air Force Research Laboratory (AFRL). The main objective of this program is to simulate the effects of space plasma characteristic of LEO and MEO environments on TFPV. Two types of TFPV, amorphous silicon (a-Si) and copper-indium-gallium-diselenide (CIGS), coated with two types of thin-film, multifunctional coatings were used for these studies. This paper reports the results of the first phase of this program, namely the results of preliminary electrostatic charging, arcing, dielectric breakdown, and collection current measurements carried out with a series of TFPV exposed to simulated space plasma at the NASA Glenn Plasma Interaction Facility. The experimental data demonstrate that multifunctional coatings developed for this program provide effective protection against the plasma environment while minimizing impact on power generation performance. This effort is part of an ongoing program led by the Space Vehicles Directorate at the AFRL devoted to the development and space qualification of TFPV and their protective coatings.

Modeling Laboratory Astrophysics Experiments using the CRASH code

NASA Astrophysics Data System (ADS)

Trantham, Matthew; Drake, R. P.; Grosskopf, Michael; Bauerle, Matthew; Kruanz, Carolyn; Keiter, Paul; Malamud, Guy; Crash Team

2013-10-01

The understanding of high energy density systems can be advanced by laboratory astrophysics experiments. Computer simulations can assist in the design and analysis of these experiments. The Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan developed a code that has been used to design and analyze high-energy-density experiments on OMEGA, NIF, and other large laser facilities. This Eulerian code uses block-adaptive mesh refinement (AMR) with implicit multigroup radiation transport and electron heat conduction. This poster/talk will demonstrate some of the experiments the CRASH code has helped design or analyze including: Radiative shocks experiments, Kelvin-Helmholtz experiments, Rayleigh-Taylor experiments, plasma sheet, and interacting jets experiments. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via grant DEFC52- 08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-FG52-09NA29548, and by the National Laser User Facility Program, grant number DE-NA0000850.

Laser-Plasma Interactions in Drive Campaign targets on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hinkel, D. E.; Callahan, D. A.; Moody, J. D.; Amendt, P. A.; Lasinski, B. F.; MacGowan, B. J.; Meeker, D.; Michel, P. A.; Ralph, J.; Rosen, M. D.; Ross, J. S.; Schneider, M. B.; Storm, E.; Strozzi, D. J.; Williams, E. A.

2016-03-01

The Drive campaign [D A Callahan et al., this conference] on the National Ignition Facility (NIF) laser [E. I. Moses, R. N. Boyd, B. A. Remington, C. J. Keane, R. Al-Ayat, Phys. Plasmas 16, 041006 (2009)] has the focused goal of understanding and optimizing the hohlraum for ignition. Both the temperature and symmetry of the radiation drive depend on laser and hohlraum characteristics. The drive temperature depends on the coupling of laser energy to the hohlraum, and the symmetry of the drive depends on beam-to-beam interactions that result in energy transfer [P. A. Michel, S. H. Glenzer, L. Divol, et al, Phys. Plasmas 17, 056305 (2010).] within the hohlraum. To this end, hohlraums are being fielded where shape (rugby vs. cylindrical hohlraums), gas fill composition (neopentane at room temperature vs. cryogenic helium), and gas fill density (increase of ∼ 150%) are independently changed. Cylindrical hohlraums with higher gas fill density show improved inner beam propagation, as should rugby hohlraums, because of the larger radius over the capsule (7 mm vs. 5.75 mm in a cylindrical hohlraum). Energy coupling improves in room temperature neopentane targets, as well as in hohlraums at higher gas fill density. In addition cross-beam energy transfer is being addressed directly by using targets that mock up one end of a hohlraum, but allow observation of the laser beam uniformity after energy transfer. Ideas such as splitting quads into “doublets” by re-pointing the right and left half of quads are also being pursued. LPI results of the Drive campaign will be summarized, and analyses of future directions presented.

High-Mach number, laser-driven magnetized collisionless shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaeffer, Derek B.; Fox, W.; Haberberger, D.

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and magnetized ambient plasma. Through time-resolved, 2-D imaging we observemore » large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. Electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. Furthermore, the simulations also show the shock separating from the piston, which we observe in the data at late experimental times.« less

High-Mach number, laser-driven magnetized collisionless shocks

DOE PAGES

Schaeffer, Derek B.; Fox, W.; Haberberger, D.; ...

2017-12-08

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and magnetized ambient plasma. Through time-resolved, 2-D imaging we observemore » large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. Electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. Furthermore, the simulations also show the shock separating from the piston, which we observe in the data at late experimental times.« less

High-Mach number, laser-driven magnetized collisionless shocks

NASA Astrophysics Data System (ADS)

Schaeffer, D. B.; Fox, W.; Haberberger, D.; Fiksel, G.; Bhattacharjee, A.; Barnak, D. H.; Hu, S. X.; Germaschewski, K.; Follett, R. K.

2017-12-01

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide a complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and a magnetized ambient plasma. Through time-resolved, 2-D imaging, we observe large density and magnetic compressions that propagate at super-Alfvénic speeds and that occur over ion kinetic length scales. The electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. The simulations also show the shock separating from the piston, which we observe in the data at late experimental times.

International Microgravity Plasma Facility IMPF: A Multi-User Modular Research Facility for Complex Plasma Research on ISS

NASA Astrophysics Data System (ADS)

Seurig, R.; Burfeindt, J.; Castegini, R.; Griethe, W.; Hofmann, P.

2002-01-01

On March 03, 2001, the PKE-Nefedov plasma experiment was successfully put into operation on board ISS. This complex plasma experiment is the predecessor for the semi-autonomous multi-user facility IMPF (International Microgravity Plasma Facility) to be flown in 2006 with an expected operational lifetime of 10 years. IMPF is envisioned to be an international research facility for investigators in the field of multi-component plasmas containing ions, electrons, and charged microparticles. This research filed is often referred to as "complex plasmas". The actual location of IMPF on ISS is not decided yet; potential infrastructure under consideration are EXPRESS Rack, Standard Interface Rack SIR, European Drawer Rack EDR, or a to be designed custom rack infrastructure on the Russian Segment. The actual development status of the DLR funded Pre-phase B Study for IMPF will be presented. For this phase, IMPF was assumed to be integrated in an EXPRESS Rack requiring four middeck lockers with two 4-PU ISIS drawers for accommodation. Technical and operational challenges, like a 240 Mbytes/sec continuous experimental data stream for 60 minutes, will be addressed. The project was funded by the German Space Agency (DLR) and was performed in close cooperation with scientists from the Max-Planck-Institute for Extraterrestical Physics in Munich, Germany.

Soft x-ray generation by a tabletop Nd:YAG/glass laser system

NASA Astrophysics Data System (ADS)

Martellucci, S.; Bellecci, C.; Francucci, M.; Gaudio, P.; Richetta, M.; Toscano, D.; Rydzy, A.; Gelfusa, M.; Ciuffa, P.

2006-08-01

The advent and development of ultra-intense tabletop laser systems has played a significant role in recent decades thanks to the wide number of applications and studies in which these systems were demonstrated to be appropriate. Among these, one of the main applications of ultra-intense radiation is generation of plasma by solid, liquid or gaseous targets. The by-product of x-radiation found many different applications such as spectroscopy, imaging, microlithography, microscopy, radiographies (in particular of biological samples), radiation-matter interaction, fundamental plasma parameter determination, astrophysics, inertial confinement fusion, high energy physics, quantum electrodynamics, and many others. In the following a brief description of our tabletop Nd:YAG/glass apparatus (facility of the Quantum Electronic and Plasma Laboratory of the University of Rome 'Tor Vergata'), together with x-ray conversion efficiency studies for different targets, are reported.

Study of the interrelation between the electrotechnical parameters of the plasma focus discharge circuit and the plasma compression dynamics on the PF-3 and PF-1000 facilities

NASA Astrophysics Data System (ADS)

Mitrofanov, K. N.; Krauz, V. I.; Grabovski, E. V.; Myalton, V. V.; Vinogradov, V. P.; Paduch, M.; Scholz, M.; Karpiński, L.

2015-05-01

The main stages of the plasma current sheath (PCS) dynamics on two plasma focus (PF) facilities with different geometries of the electrode system, PF-3 (Filippov type) and PF-1000 (Mather type), were studied by analyzing the results of the current and voltage measurements. Some dynamic characteristics, such as the PCS velocity in the acceleration phase in the Mather-type facility (PF-1000), the moment at which the PCS reaches the anode end, and the plasma velocity in the radial stage of plasma compression in the PF-3 Filippov-type facility, were determined from the time dependence of the inductance of the discharge circuit with a dynamic plasma load. The energy characteristics of the discharge circuit of the compressing PCS were studied for different working gases (deuterium, argon, and neon) at initial pressures of 1.5-3 Torr in discharges with energies of 0.3-0.6 MJ. In experiments with deuterium, correlation between the neutron yield and the electromagnetic energy deposited directly in the compressed PCS was investigated.

Study of Plasma Energization during Magnetic Reconnection in the FLARE (Facility for Laboratory Reconnection Experiments)

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W.; Bale, S.; Carter, T.; Crocker, N.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.; Chen, Y.; Cutler, R.; Fox, W.; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.

2015-11-01

Various regimes or ``phases'' are identified in a magnetic reconnection ``phase diagram'' which classifies different coupling mechanisms from the global system scales to the local dissipation scales. The FLARE device (http://flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton to provide access to all of these phases directly relevant to space, solar, astrophysical, and fusion plasmas. Study of plasma energization during magnetic reconnection is one of major topics for the FLARE facility, which is planned to be a user facility. The motivating major physics questions regarding plasma energization and the planned collaborative research on these topics will be presented and discussed. Supported by NSF.

Center for Multiscale Plasma Dynamics: Report on Activities (UCLA/MIT), 2009-2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Troy Carter

2011-04-18

The final 'phaseout' year of the CMPD ended July 2010; a no cost extension was requested until May 2011 in order to enable the MIT subcontract funds to be fully utilized. Research progress over this time included verification and validation activities for the BOUT and BOUT++ code, studies of spontaneous reconnection in the VTF facility at MIT, and studies of the interaction between Alfven waves and drift waves in LAPD. The CMPD also hosted the 6th plasma physics winter school in 2010 (jointly with the NSF frontier center the Center for Magnetic Self-Organization, significant funding came from NSF for thismore » most recent iteration of the Winter School).« less

Interaction of Intense Lasers and Relativistic Electron Beams with Solids, Gases and Plasmas

DTIC Science & Technology

1993-06-01

June 18, 1993. The main subject was the identification of research opportunities and needs that are at- tractive for investigation using the HAARP ...warming and global change. Highly leveraged cooperative or collaborative programs exploring the HAARP facility and diagnostic complement in conjunction...1. Diagnostic issues - HF diagnostics. 1.1 Possible use of HAARP transmitter as a receiving antenna. 1.2 Possible addition of a "big" receiving

Specular reflectivity and hot-electron generation in high-contrast relativistic laser-plasma interactions

NASA Astrophysics Data System (ADS)

Kemp, Gregory Elijah

Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic laser-plasma interactions. Spatial, temporal and spectral properties of the incident and specular pulses, both near and far away from the interaction region where experimental measurements are obtained, are used to benchmark simulations designed to infer dominant hot-electron acceleration mechanisms and their corresponding energy/angular distributions. To handle this highly coupled interaction, I employed particle-in-cell modeling using a wide variety of algorithms (verified to be numerically stable and consistent with analytic expressions) and physical models (validated by experimental results) to reasonably model the interaction's sweeping range of plasma densities, temporal and spatial scales, electromagnetic wave propagation and its interaction with solid density matter. Due to the fluctuations in the experimental conditions and limited computational resources, only a limited number of full-scale simulations were performed under typical experimental conditions to infer the relevant physical phenomena in the interactions. I show the usefulness of the often overlooked specular reflectivity measurements in constraining both high and low-contrast simulations, as well as limitations of their experimental interpretations. Using these experimental measurements to reasonably constrain the simulation results, I discuss the sensitivity of relativistic electron generation in ultra-intense laser plasma interactions to initial target conditions and the dynamic evolution of the interaction region.

ORION laser target diagnostics.

PubMed

Bentley, C D; Edwards, R D; Andrew, J E; James, S F; Gardner, M D; Comley, A J; Vaughan, K; Horsfield, C J; Rubery, M S; Rothman, S D; Daykin, S; Masoero, S J; Palmer, J B; Meadowcroft, A L; Williams, B M; Gumbrell, E T; Fyrth, J D; Brown, C R D; Hill, M P; Oades, K; Wright, M J; Hood, B A; Kemshall, P

2012-10-01

The ORION laser facility is one of the UK's premier laser facilities which became operational at AWE in 2010. Its primary mission is one of stockpile stewardship, ORION will extend the UK's experimental plasma physics capability to the high temperature, high density regime relevant to Atomic Weapons Establishment's (AWE) program. The ORION laser combines ten laser beams operating in the ns regime with two sub ps short pulse chirped pulse amplification beams. This gives the UK a unique combined long pulse/short pulse laser capability which is not only available to AWE personnel but also gives access to our international partners and visiting UK academia. The ORION laser facility is equipped with a comprehensive suite of some 45 diagnostics covering optical, particle, and x-ray diagnostics all able to image the laser target interaction point. This paper focuses on a small selection of these diagnostics.

Design and Demonstration of a Material-Plasma Exposure Target Station for Neutron Irradiated Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, Juergen; Aaron, A. M.; Bell, Gary L.

2015-10-20

Fusion energy is the most promising energy source for the future, and one of the most important problems to be solved progressing to a commercial fusion reactor is the identification of plasma-facing materials compatible with the extreme conditions in the fusion reactor environment. The development of plasma–material interaction (PMI) science and the technology of plasma-facing components are key elements in the development of the next step fusion device in the United States, the so-called Fusion Nuclear Science Facility (FNSF). All of these PMI issues and the uncertain impact of the 14-MeV neutron irradiation have been identified in numerous expert panelmore » reports to the fusion community. The 2007 Greenwald report classifies reactor plasma-facing materials (PFCs) and materials as the only Tier 1 issues, requiring a “. . . major extrapolation from the current state of knowledge, need for qualitative improvements and substantial development for both the short and long term.” The Greenwald report goes on to list 19 gaps in understanding and performance related to the plasma–material interface for the technology facilities needed for DEMO-oriented R&D and DEMO itself. Of the 15 major gaps, six (G7, G9, G10, G12, G13) can possibly be addressed with ORNL’s proposal of an advanced Material Plasma Exposure eXperiment. Establishing this mid-scale plasma materials test facility at ORNL is a key element in ORNL’s strategy to secure a leadership role for decades of fusion R&D. That is to say, our end goal is to bring the “signature facility” FNSF home to ORNL. This project is related to the pre-conceptual design of an innovative target station for a future Material–Plasma Exposure eXperiment (MPEX). The target station will be designed to expose candidate fusion reactor plasma-facing materials and components (PFMs and PFCs) to conditions anticipated in fusion reactors, where PFCs will be exposed to dense high-temperature hydrogen plasmas providing steady-state heat fluxes of 5–20 MW/m 2 and ion fluxes up to 10 24 m -2s -1. Since PFCs will have to withstand neutron irradiation displacement damage up to 50 dpa, the target station design must accommodate radioactive specimens (materials to be irradiated in HFIR or at SNS) to enable investigations of the impact of neutron damage on materials. Therefore, the system will have to be able to install and extract irradiated specimens using equipment and methods to avoid sample modification, control contamination, and minimize worker dose. Included in the design considerations will be an assessment of all the steps between neutron irradiation and post-exposure materials examination/characterization, as well as an evaluation of the facility hazard categorization. In particular, the factors associated with the acquisition of radioactive specimens and their preparation, transportation, experimental configuration at the plasma-specimen interface, post-plasma-exposure sample handling, and specimen preparation will be evaluated. Neutronics calculations to determine the dose rates of the samples were carried out for a large number of potential plasma-facing materials.« less

Historical overview of HF ionospheric modification research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, W.E.; Duncan, L.M.

1990-10-01

Radio waves have inadvertently modified the Earth's ionosphere since the Luxembourg observations of Tellegen in 1933 and perhaps since Marconi in 1901. The history of ionospheric modification by radio waves is reviewed, beginning with Marconi, describing the Luxembourg effect and its explanations, and its early use to deduce the properties of the lower ionosphere in the 1930s. The measurements became more sophisticated in the 1950s, leading to the call for high-power high-frequency modification experiments in the upper ionosphere. Beginning in 1970, radio facilities became available of sufficient powers to induce changes in the ionospheric plasma detectable by a wide arraymore » of diagnostic instruments and techniques. A summary of these effects is presented based upon work up to 1990. These studies were originally motivated as a means of better understanding the natural ionosphere using a weak perturbational approach. However, a rich spectrum of nonlinear wave-plasma interactions was quickly discovered and ionospheric modification research became strongly motivated by issues in basic plasma physics. The ionosphere and near-Earth space are now exploited as an exceptional plasma laboratory-without-walls for the study of fundamental plasma processes requiring large spatial or temporal scales. Here we present a brief overview of these processes and phenomena, illustrated using results obtained from the Arecibo ionospheric modification facilities. The lessons learned and phenomena explored thus far offer many opportunities for controlling the ionospheric environment critical to many civilian and military telecommunications systems, both to disrupt systems normally operational and to create new propagation paths otherwise unavailable.« less

Experimental Validation Plan for the Xolotl Plasma-Facing Component Simulator Using Tokamak Sample Exposures

NASA Astrophysics Data System (ADS)

Chan, V. S.; Wong, C. P. C.; McLean, A. G.; Luo, G. N.; Wirth, B. D.

2013-10-01

The Xolotl code under development by PSI-SciDAC will enhance predictive modeling capability of plasma-facing materials under burning plasma conditions. The availability and application of experimental data to compare to code-calculated observables are key requirements to validate the breadth and content of physics included in the model and ultimately gain confidence in its results. A dedicated effort has been in progress to collect and organize a) a database of relevant experiments and their publications as previously carried out at sample exposure facilities in US and Asian tokamaks (e.g., DIII-D DiMES, and EAST MAPES), b) diagnostic and surface analysis capabilities available at each device, and c) requirements for future experiments with code validation in mind. The content of this evolving database will serve as a significant resource for the plasma-material interaction (PMI) community. Work supported in part by the US Department of Energy under GA-DE-SC0008698, DE-AC52-07NA27344 and DE-AC05-00OR22725.

Plasma current collection of Z-93 thermal control paint as measured in the Lewis Research Center's plasma interaction facility

NASA Technical Reports Server (NTRS)

Hillard, G. Barry

1993-01-01

A sample of Z-93 thermal control paint was exposed to a simulated space environment in a plasma chamber. The sample was biased through a series of voltages ranging from -100 volts to +300 volts and electron and ion currents were measured. Currents were found to be in the micro-ampere range indicating that the material remains a reasonably good insulator under plasma conditions. As a second step, the sample was left in the chamber for six days and retested. Collected currents were reduced by from two to five times from the previous values indicating a substantial loss of conductivity. As a final test, the sample was removed, exposed to room conditions for two days, and returned to the chamber. Current measurements showed that the sample had partially recovered the lost conductivity. In addition to presenting these results, this report documents all of the experimental data as well as the statistical analyses performed.

Laser plasma interaction on rugby hohlraum on the Omega Laser Facility: Comparisons between cylinder, rugby, and elliptical hohlraums

NASA Astrophysics Data System (ADS)

Masson-Laborde, P. E.; Monteil, M. C.; Tassin, V.; Philippe, F.; Gauthier, P.; Casner, A.; Depierreux, S.; Neuville, C.; Villette, B.; Laffite, S.; Seytor, P.; Fremerye, P.; Seka, W.; Teychenné, D.; Debayle, A.; Marion, D.; Loiseau, P.; Casanova, M.

2016-02-01

Gas-filled rugby-shaped hohlraums have demonstrated high performances compared to a classical similar diameter cylinder hohlraum with a nearly 40% increase of x-ray drive, 10% higher measured peak drive temperature, and an increase in neutron production. Experimental comparisons have been done between rugby, cylinder, and elliptical hohlraums. The impact of these geometry differences on the laser plasma instabilities is examined. Using comparisons with hydrodynamic simulations carried out with the code FCI2 and postprocessed by Piranah, we have been able to reproduce the stimulated Raman and Brillouin scattering spectrum of the different beams. Using a methodology based on a statistical analysis for the gain calculations, we show that the behavior of the laser plasma instabilities in rugby hohlraums can be reproduced. The efficiency of laser smoothing techniques to mitigate these instabilities are discussed, and we show that while rugby hohlraums exhibit more laser plasma instabilities than cylinder hohlraum, the latter can be mitigated in the case of an elliptical hohlraum.

Study of the interrelation between the electrotechnical parameters of the plasma focus discharge circuit and the plasma compression dynamics on the PF-3 and PF-1000 facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitrofanov, K. N., E-mail: mitrkn@inbox.ru; Krauz, V. I., E-mail: krauz-vi@nrcki.ru, E-mail: vkrauz@yandex.ru; Grabovski, E. V.

The main stages of the plasma current sheath (PCS) dynamics on two plasma focus (PF) facilities with different geometries of the electrode system, PF-3 (Filippov type) and PF-1000 (Mather type), were studied by analyzing the results of the current and voltage measurements. Some dynamic characteristics, such as the PCS velocity in the acceleration phase in the Mather-type facility (PF-1000), the moment at which the PCS reaches the anode end, and the plasma velocity in the radial stage of plasma compression in the PF-3 Filippov-type facility, were determined from the time dependence of the inductance of the discharge circuit with amore » dynamic plasma load. The energy characteristics of the discharge circuit of the compressing PCS were studied for different working gases (deuterium, argon, and neon) at initial pressures of 1.5–3 Torr in discharges with energies of 0.3–0.6 MJ. In experiments with deuterium, correlation between the neutron yield and the electromagnetic energy deposited directly in the compressed PCS was investigated.« less

Magnetic field generation, Weibel-mediated collisionless shocks, and magnetic reconnection in colliding laser-produced plasmas

NASA Astrophysics Data System (ADS)

Fox, W.; Bhattacharjee, A.; Fiksel, G.

2016-10-01

Colliding plasmas are ubiquitous in astrophysical environments and allow conversion of kinetic energy into heat and, most importantly, the acceleration of particles to extremely high energies to form the cosmic ray spectrum. In collisionless astrophysical plasmas, kinetic plasma processes govern the interaction and particle acceleration processes, including shock formation, self-generation of magnetic fields by kinetic plasma instabilities, and magnetic field compression and reconnection. How each of these contribute to the observed spectra of cosmic rays is not fully understood, in particular both shock acceleration processes and magnetic reconnection have been proposed. We will review recent results of laboratory astrophysics experiments conducted at high-power, inertial-fusion-class laser facilities, which have uncovered significant results relevant to these processes. Recent experiments have now observed the long-sought Weibel instability between two interpenetrating high temperature plasma plumes, which has been proposed to generate the magnetic field necessary for shock formation in unmagnetized regimes. Secondly, magnetic reconnection has been studied in systems of colliding plasmas using either self-generated magnetic fields or externally applied magnetic fields, and show extremely fast reconnection rates, indicating fast destruction of magnetic energy and further possibilities to accelerate particles. Finally, we highlight kinetic plasma simulations, which have proven to be essential tools in the design and interpretation of these experiments.

The interaction of spacecraft high voltage power systems with the space plasma environment

NASA Technical Reports Server (NTRS)

Domitz, S.; Grier, N. T.

1974-01-01

The development of spacecraft with electrical loads that require high voltage power is discussed. The high voltage solar array has been considered for supplying d.c. power directly to high voltage loads such as ion thrusters and communication tubes without intermediate power processing. Space power stations for transferring solar power to earth are being studied in the 40 kilovolt, multikilowatt regime. Analytical and experimental studies have determined that with the advent of high voltage power, new problems will arise through the interaction of the high voltage surfaces with the charged particle environment of space. The interactive environment has been identified and duplicated to some extent in simulation facilities at NASA-Lewis Research Center and at several contractor locations.

PALS laser-driven radiative jets for astrophysical and ICF applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pisarczyk, T.; Kasperczuk, A.; Stenz, Ch.

2008-03-19

High speed, well-collimated plasma jets were generated in the interaction of defocused single laser beam with planar, massive Cu target. The experiment was carried out at the iodine laser facility (Prague Asterix Laser System--PALS) using the third harmonic beam (0.438 {mu}m) with a pulse duration of 250 ps (FWHM) and an energy of 100 J. The information about geometry of plasma expansion, plasma dynamics and electron density were obtained by means of a 3-frame interferometric system. The plasma jet parameters reach the following values: the velocity up to 7x10{sup 7} cm/s, the internal Mach number greater than 10 and themore » electron density above 10{sup 19} cm{sup -3}. The jet characteristics are appropriate for the astrophysical and ICF applications. To ensure the interaction of this jet with gas or plasma as an ambient medium, a high-pressure supersonic gas nozzle was used, which created a cylindrical column of Ar or He. The results of first experiments dedicated to studies of collision of such a jet with a gas cloud are also presented. They clearly show the effect of shocks formation in ambient gases (He and Ar) due to the jet action. In the case of He the shock waves have usually a conical shape with a thickness of 1-1.5 mm, whereas in the case of Ar, the shock wave configuration is more complex and its thickness is less than 1 mm.« less

Physics of Tokamak Plasma Start-up

NASA Astrophysics Data System (ADS)

Mueller, Dennis

2012-10-01

This tutorial describes and reviews the state-of-art in tokamak plasma start-up and its importance to next step devices such as ITER, a Fusion Nuclear Science Facility and a Tokamak/ST demo. Tokamak plasma start-up includes breakdown of the initial gas, ramp-up of the plasma current to its final value and the control of plasma parameters during those phases. Tokamaks rely on an inductive component, typically a central solenoid, which has enabled attainment of high performance levels that has enabled the construction of the ITER device. Optimizing the inductive start-up phase continues to be an area of active research, especially in regards to achieving ITER scenarios. A new generation of superconducting tokamaks, EAST and KSTAR, experiments on DIII-D and operation with JET's ITER-like wall are contributing towards this effort. Inductive start-up relies on transformer action to generate a toroidal loop voltage and successful start-up is determined by gas breakdown, avalanche physics and plasma-wall interaction. The goal of achieving steady-sate tokamak operation has motivated interest in other methods for start-up that do not rely on the central solenoid. These include Coaxial Helicity Injection, outer poloidal field coil start-up, and point source helicity injection, which have achieved 200, 150 and 100 kA respectively of toroidal current on closed flux surfaces. Other methods including merging reconnection startup and Electron Bernstein Wave (EBW) plasma start-up are being studied on various devices. EBW start-up generates a directed electron channel due to wave particle interaction physics while the other methods mentioned rely on magnetic helicity injection and magnetic reconnection which are being modeled and understood using NIMROD code simulations.

44th Annual Anomalous Absorption Conference

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beg, Farhat

Conference Grant Report July 14, 2015 Submitted to the U. S. Department of Energy Attn: Dr. Sean Finnegan By the University of California, San Diego 9500 Gilman Drive La Jolla, California 92093 On behalf of the 44th Annual Anomalous Absorption Conference 8-13 June 2014, in Estes Park, Colorado Support Requested: $10,100 Amount expended: $3,216.14 Performance Period: 1 March 20 14 to 28 February 20 15 Principal Investigator Dr. Farhat Beg Center for Energy Research University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0417 858-822-1266 (telephone) 858-534-4543 (fax) fbeg@ucsd.edu Administrative Point of Contact: Brandi Pate, 858-534-0851, blpate®ucsd.edu I.more » Background The forty-fourth Anomalous Absorption Conference was held in Estes Park, Colorado from June 5-8, 2014 (aac2014.ucsd.edu). The first Anomalous Absorption Conference was held in 1971 to assemble experts in the poorly understood area of laser-plasma absorption. The goal of that conference was to address the anomalously large laser absorption seen in plasma experiments with respect to the laser absorption predicted by linear plasma theory. Great progress in this research area has been made in the decades since that first meeting, due in part to the scientific interactions that have occurred annually at this conference. Specifically, this includes the development of nonlinear laser-plasma theory and the simulation of laser interactions with plasmas. Each summer since that first meeting, this week-long conference has been held at unique locations in North America as a scientific forum for intense scientific exchanges relevant to the interaction of laser radiation with plasmas. Responsibility for organizing the conference has traditional rotated each year between the major Inertial Confinement Fusion (ICF) laboratories and universities including LANL, LLNL, LLE, UCLA UC Davis and NRL. As the conference has matured over the past four decades, its technical footprint has expanded beyond ICF-related laser-plasma interactions to encompass closely related technical areas including laser particle acceleration, high-intensity laser effects, short­ pulse laser interactions, PIC and Vlasov/rad-hydro modeling, inertial and magnetic fusion plasmas, advanced plasma diagnostics, alternate ignition schemes, EOS/transport/opacity, and this year, x­ ray free-electron lasers and their applications. The conference continues to be a showcase for the presentation and discussion of the latest developments in these areas. II. Meeting Report The conference was extremely successful with more than one hundred participants. There were ninety-nine (99) abstracts submitted. There were forty-four (44) presentations including eleven (11) invited talks. The following topics were covered: a) Radiation Hydrodynamics b) Implosion Plasma Kinetic Effects c) Alternate Ignition Schemes d) Astrophysical Phenomena e) Opacity/Transport/EOS f) High Power Lasers and Facilities g) High-Intensity Laser-Matter Interactions h) Hydrodynamics and Hydro-instabilities i) Hot Dense Plasma Atomic Processes j) High Energy Density Physics k) Laser Particle Acceleration Physics l) Advanced Plasma Diagnostics m) Advanced light sources and applications Despite significant advertising, there were two students who applied for the travel grants: Charlie Jarrott and Joohwan Kim. The total funds expended were $3,216.14.« less

Overview on the target fabrication facilities at ELI-NP and ongoing strategies

NASA Astrophysics Data System (ADS)

Gheorghiu, C. C.; Leca, V.; Popa, D.; Cernaianu, M. O.; Stutman, D.

2016-10-01

Along with the development of petawatt class laser systems, the interaction between high power lasers and matter flourished an extensive research, with high-interest applications like: laser nuclear physics, proton radiography or cancer therapy. The new ELI-NP (Extreme Light Infrastructure - Nuclear Physics) petawatt laser facility, with 10PW and ~ 1023W/cm2 beam intensity, is one of the innovative projects that will provide novel research of fundamental processes during light-matter interaction. As part of the ELI-NP facility, Targets Laboratory will provide the means for in-house manufacturing and characterization of the required targets (mainly solid ones) for the experiments, in addition to the research activity carried out in order to develop novel target designs with improved performances. A description of the Targets Laboratory with the main pieces of equipment and their specifications are presented. Moreover, in view of the latest progress in the target design, one of the proposed strategies for the forthcoming experiments at ELI-NP is also described, namely: ultra-thin patterned foil of diamond-like carbon (DLC) coated with a carbon-based ultra-low density layer. The carbon foam which behaves as a near-critical density plasma, will allow the controlled-shaping of the laser pulse before the main interaction with the solid foil. Particular emphasis will be directed towards the target's design optimization, by simulation tests and tuning the key-properties (thickness/length, spacing, density foam, depth, periodicity etc.) which are expected to have a crucial effect on the laser-matter interaction process.

Working Group 5: Measurements technology and active experiments

NASA Technical Reports Server (NTRS)

Whipple, E.; Barfield, J. N.; Faelthammar, C.-G.; Feynman, J.; Quinn, J. N.; Roberts, W.; Stone, N.; Taylor, W. L.

1986-01-01

Technology issues identified by working groups 5 are listed. (1) New instruments are needed to upgrade the ability to measure plasma properties in space. (2) Facilities should be developed for conducting a broad range of plasma experiments in space. (3) The ability to predict plasma weather within magnetospheres should be improved and a capability to modify plasma weather developed. (4) Methods of control of plasma spacecraft and spacecraft plasma interference should be upgraded. (5) The space station laboratory facilities should be designed with attention to problems of flexibility to allow for future growth. These issues are discussed.

Advances in petascale kinetic plasma simulation with VPIC and Roadrunner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowers, Kevin J; Albright, Brian J; Yin, Lin

2009-01-01

VPIC, a first-principles 3d electromagnetic charge-conserving relativistic kinetic particle-in-cell (PIC) code, was recently adapted to run on Los Alamos's Roadrunner, the first supercomputer to break a petaflop (10{sup 15} floating point operations per second) in the TOP500 supercomputer performance rankings. They give a brief overview of the modeling capabilities and optimization techniques used in VPIC and the computational characteristics of petascale supercomputers like Roadrunner. They then discuss three applications enabled by VPIC's unprecedented performance on Roadrunner: modeling laser plasma interaction in upcoming inertial confinement fusion experiments at the National Ignition Facility (NIF), modeling short pulse laser GeV ion acceleration andmore » modeling reconnection in magnetic confinement fusion experiments.« less

Center for Multiscale Plasma Dynamics: Report on Activities (UCLA/MIT), 2009-2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Troy Alan

2014-10-03

The final “phaseout” year of the CMPD ended July 2010; a no cost extension was requested until May 2011 in order to enable the MIT subcontract funds to be fully utilized. Research progress over this time included verification and validation activities for the BOUT and BOUT++ code, studies of spontaneous reconnection in the VTF facility at MIT, and studies of the interaction between Alfv´en waves and drift waves in LAPD. The CMPD also hosted the 6th plasma physics winter school in 2010 (jointly with the NSF frontier center the Center for Magnetic Self-Organization, significant funding came from NSF for thismore » most recent iteration of theWinter School).« less

Studies for the Loss of Atomic and Molecular Species from Io

NASA Technical Reports Server (NTRS)

Smyth, William H.

1998-01-01

Updated neutral emission rates for electron impact excitation of atomic oxygen and sulfur based upon the Collisional Radiative Equilibrium (COREQ) model have been incorporated in the neutral cloud models. An empirical model for the Io plasma torus wake has also been added in the neutral cloud model to describe important enhancements in the neutral emission rates and lifetime rates in this spatial region. New insights into Io's atmosphere and its interaction with the plasma torus are discussed. These insights are based upon an initial comparison of simultaneous lo observations on October 14, 1997, for [0I] 6300 Angstrom emissions acquired by groundbased facilities and several ultraviolet emissions acquired by HST/STIS in the form of high-spatial- resolution images for atomic oxygen and sulfur.

Unique capabilities for ICF and HEDP research with the KrF laser

NASA Astrophysics Data System (ADS)

Obenschain, Stephen; Bates, Jason; Chan, Lop-Yung; Karasik, Max; Kehne, David; Sethian, John; Serlin, Victor; Weaver, James; Oh, Jaechul; Jenkins, Bruce; Lehmberg, Robert; Hegeler, Frank; Terrell, Stephen; Aglitskiy, Yefim; Schmitt, Andrew

2014-10-01

The krypton-fluoride (KrF) laser provides the shortest wavelength, broadest bandwidth and most uniform target illumination of all developed high-energy lasers. For directly driven targets these characteristics result in higher and more uniform ablation pressures as well as higher intensity thresholds for laser-plasma instability. The ISI beam smoothing scheme implemented on the NRL Nike KrF facility allows easy implementation of focal zooming where the laser radial profile is varied during the laser pulse. The capability for near continuous zooming with KrF would be valuable towards minimizing the effects of cross beam energy transport (CBET) in directly driven capsule implosions. The broad bandwidth ISI beam smoothing that is utilized with the Nike KrF facility may further inhibit certain laser plasma instability. In this presentation we will summarize our current understanding of laser target interaction with the KrF laser and the benefits it provides for ICF and certain HEDP experiments. Status and progress in high-energy KrF laser technology will also be discussed. Work supported by the Deparment of Energy, NNSA.

Rugby and elliptical-shaped hohlraums experiments on the OMEGA laser facility

NASA Astrophysics Data System (ADS)

Tassin, Veronique; Monteil, Marie-Christine; Depierreux, Sylvie; Masson-Laborde, Paul-Edouard; Philippe, Franck; Seytor, Patricia; Fremerye, Pascale; Villette, Bruno

2017-10-01

We are pursuing on the OMEGA laser facility indirect drive implosions experiments in gas-filled rugby-shaped hohlraums in preparation for implosion plateforms on LMJ. The question of the precise wall shape of rugby hohlraum has been addressed as part of future megajoule-scale ignition designs. Calculations show that elliptical-shaped holhraum is more efficient than spherical-shaped hohlraum. There is less wall hydrodynamics and less absorption for the inner cone, provided a better control of time-dependent symmetry swings. In this context, we have conducted a series of experiments on the OMEGA laser facility. The goal of these experiments was therefore to characterize energetics with a complete set of laser-plasma interaction measurements and capsule implosion in gas-filled elliptical-shaped hohlraum with comparison with spherical-shaped hohlraum. Experiments results are discussed and compared to FCI2 radiation hydrodynamics simulations.

View Factor and Radiation-Hydrodynamic Simulations of Gas-Filled Outer-Quad-Only Hohlraums at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Young, Christopher; Meezan, Nathan; Landen, Otto

2017-10-01

A cylindrical National Ignition Facility hohlraum irradiated exclusively by NOVA-like outer quads (44 .5° and 50° beams) is proposed to minimize laser plasma interaction (LPI) losses and avoid problems with propagating the inner (23 .5° and 30°) beams. Symmetry and drive are controlled by shortening the hohlraum, using a smaller laser entrance hole (LEH), beam phasing the 44 .5° and 50° beams, and correcting the remaining P4 asymmetry with a capsule shim. Ensembles of time-resolved view factor simulations help narrow the design space of the new configuration, with fine tuning provided by the radiation-hydrodynamic code HYDRA. Prepared by LLNL under Contract DE-AC52-07NA27344.

A recoverable gas-cell diagnostic for the National Ignition Facility.

PubMed

Ratkiewicz, A; Berzak Hopkins, L; Bleuel, D L; Bernstein, L A; van Bibber, K; Cassata, W S; Goldblum, B L; Siem, S; Velsko, C A; Wiedeking, M; Yeamans, C B

2016-11-01

The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of nat Xe and discuss future work to study the strength of interactions between plasma and nuclei.

Fourth-generation plasma immersion ion implantation and deposition facility for hybrid surface modification layer fabrication.

PubMed

Wang, Langping; Huang, Lei; Xie, Zhiwen; Wang, Xiaofeng; Tang, Baoyin

2008-02-01

The fourth-generation plasma immersion ion implantation and deposition (PIIID) facility for hybrid and batch treatment was built in our laboratory recently. Comparing with our previous PIIID facilities, several novel designs are utilized. Two multicathode pulsed cathodic arc plasma sources are fixed on the chamber wall symmetrically, which can increase the steady working time from 6 h (the single cathode source in our previous facilities) to about 18 h. Meanwhile, the inner diameter of the pulsed cathodic arc plasma source is increased from the previous 80 to 209 mm, thus, large area metal plasma can be obtained by the source. Instead of the simple sample holder in our previous facility, a complex revolution-rotation sample holder composed of 24 shafts, which can rotate around its axis and adjust its position through revolving around the center axis of the vacuum chamber, is fixed in the center of the vacuum chamber. In addition, one magnetron sputtering source is set on the chamber wall instead of the top cover in the previous facility. Because of the above characteristic, the PIIID hybrid process involving ion implantation, vacuum arc, and magnetron sputtering deposition can be acquired without breaking vacuum. In addition, the PIIID batch treatment of cylinderlike components can be finished by installing these components on the rotating shafts on the sample holder.

Using the Tritium Plasma Experiment to evaluate ITER PFC safety

NASA Astrophysics Data System (ADS)

Longhurst, Glen R.; Anderl, Robert A.; Bartlit, John R.; Causey, Rion A.; Haines, John R.

The Tritium Plasma Experiment was assembled at Sandia National Laboratories, Livermore to investigate interactions between dense plasmas at low energies and plasma-facing component materials. This apparatus has the unique capability of replicating plasma conditions in a tokamak divertor with particle flux densities of 2 x 10(exp 19) ions/((sq cm)(s)) and a plasma temperature of about 15 eV using a plasma that includes tritium. With the closure of the Tritium Research Laboratory at Livermore, the experiment was moved to the Tritium Systems Test Assembly facility at Los Alamos National Laboratory. An experimental program has been initiated there using the Tritium Plasma Experiment to examine safety issues related to tritium in plasma-facing components, particularly the ITER divertor. Those issues include tritium retention and release characteristics, tritium permeation rates and transient times to coolant streams, surface modification and erosion by the plasma, the effects of thermal loads and cycling, and particulate production. A considerable lack of data exists in these areas for many of the materials, especially beryllium, being considered for use in ITER. Not only will basic material behavior with respect to safety issues in the divertor environment be examined, but innovative techniques for optimizing performance with respect to tritium safety by material modification and process control will be investigated. Supplementary experiments will be carried out at the Idaho National Engineering Laboratory and Sandia National Laboratory to expand and clarify results obtained on the Tritium Plasma Experiment.

Spectroscopic studies of the parameters of plasma jets during their propagation in the background plasma on the PF-3 facility

NASA Astrophysics Data System (ADS)

Dan'ko, S. A.; Ananyev, S. S.; Kalinin, Yu G.; Krauz, V. I.; Myalton, V. V.

2017-04-01

This paper presents measurement results of neon and helium plasma parameters in axial jets generated in plasma focus discharge. They were obtained in the course of experiments on laboratory modeling of astrophysical jets performed at the PF-3 facility. The plasma concentration was determined according to Stark broadening of spectral lines; the ionization temperature was determined by the average ion charge. The values of the concentration and temperature of jet plasma and background plasma at two distances from the pinch are also presented. In addition, an estimation was made of the heat content losses of the neon and helium jets during their movement through the surrounding medium.

A Fusion Nuclear Science Facility for a fast-track path to DEMO

DOE PAGES

Garofalo, Andrea M.; Abdou, M.; Canik, John M.; ...

2014-10-01

An accelerated fusion energy development program, a “fast-track” approach, requires developing an understanding of fusion nuclear science (FNS) in parallel with research on ITER to study burning plasmas. A Fusion Nuclear Science Facility (FNSF) in parallel with ITER provides the capability to resolve FNS feasibility issues related to power extraction, tritium fuel sustainability, and reliability, and to begin construction of DEMO upon the achievement of Q~10 in ITER. Fusion nuclear components, including the first wall (FW)/blanket, divertor, heating/fueling systems, etc. are complex systems with many inter-related functions and different materials, fluids, and physical interfaces. These in-vessel nuclear components must operatemore » continuously and reliably with: (a) Plasma exposure, surface particle & radiation loads, (b) High energy 2 neutron fluxes and their interactions in materials (e.g. peaked volumetric heating with steep gradients, tritium production, activation, atomic displacements, gas production, etc.), (c) Strong magnetic fields with temporal and spatial variations (electromagnetic coupling to the plasma including off-normal events like disruptions), and (d) a High temperature, high vacuum, chemically active environment. While many of these conditions and effects are being studied with separate and multiple effect experimental test stands and modeling, fusion nuclear conditions cannot be completely simulated outside the fusion environment. This means there are many new multi-physics, multi-scale phenomena and synergistic effects yet to be discovered and accounted for in the understanding, design and operation of fusion as a self-sustaining, energy producing system, and significant experimentation and operational experience in a true fusion environment is an essential requirement. In the following sections we discuss the FNSF objectives, describe the facility requirements and a facility concept and operation approach that can accomplish those objectives, and assess the readiness to construct with respect to several key FNSF issues: materials, steady-state operation, disruptions, power exhaust, and breeding blanket. Finally we present our conclusions.« less

A technique for synergistic atomic oxygen and vacuum ultraviolet radiation durability evaluation of materials for use in LEO

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Banks, Bruce A.

1996-01-01

Material erosion data collected during flight experiments such as the Environmental Oxygen Interaction with Materials (EOIM)-3 and the Long Duration Exposure Facility (LDEF) have raised questions as to the sensitivity of material erosion to levels of atomic oxygen exposure and vacuum ultraviolet (VUV) radiation. The erosion sensitivity of some materials such as FEP Teflon used as a thermal control material on satellites in low Earth orbit (LEO), is particularly important but difficult to determine. This is in large part due to the inability to hold all but one exposure parameter constant during a flight experiment. This is also difficult to perform in a ground based facility, because often the variation of the level of atomic oxygen or VUV radiation also results in a change in the level of the other parameter. A facility has been developed which allows each parameter to be changed almost independently and offer broad area exposure. The resulting samples can be made large enough for mechanical testing. The facility uses an electron cyclotron resonance plasma source to provide the atomic oxygen. A series of glass plates is used to focus the atomic oxygen while filtering the VUV radiation from the plasma source. After filtering, atomic oxygen effective flux levels can still be measured which are as high as 7 x 10(exp 15) atoms/cm(exp 2)-sec which is adequate for accelerated testing. VUV radiation levels after filtering can be as low as 0.3 suns. Additional VUV suns can be added with the use of deuterium lamps which allow the VUV level to be changed while keeping the flux of atomic oxygen constant. This paper discusses the facility, and results from exposure of Kapton and FEP at pre-determined atomic oxygen flux and VUV sun levels.

Surface-wave-sustained plasma torch for water treatment

NASA Astrophysics Data System (ADS)

Marinova, P.; Benova, E.; Todorova, Y.; Topalova, Y.; Yotinov, I.; Atanasova, M.; Krcma, F.

2018-02-01

In this study the effects of water treatment by surface-wave-sustained plasma torch at 2.45 GHz are studied. Changes in two directions are obtained: (i) changes of the plasma characteristics during the interaction with the water; (ii) water physical and chemical characteristics modification as a result of the plasma treatment. In addition, deactivation of Gram positive and Gram negative bacteria in suspension are registered. A number of charged and excited particles from the plasma interact with the water. As a result the water chemical and physical characteristics such as the water conductivity, pH, H2O2 concentration are modified. It is observed that the effect depends on the treatment time, wave power, and volume of the treated liquid. At specific discharge conditions determined by the wave power, gas flow, discharge tube radius, thickness and permittivity, the surface-wave-sustained discharge (SWD) operating at atmospheric pressure in argon is strongly non-equilibrium with electron temperature T e much higher than the temperature of the heavy particles (gas temperature T g). It has been observed that SWD argon plasma with T g close to the room temperature is able to produce H2O2 in the water with high efficiency at short exposure times (less than 60 sec). The H2O2 decomposition is strongly dependant on the temperature thus the low operating gas temperature is crucial for the H2O2 production efficiency. After scaling up the device, the observed effects can be applied for the waste water treatment in different facilities. The innovation will be useful especially for the treatment of waters and materials for medical application.

Preparation of Caco-2 cell sheets using plasma polymerised acrylic acid as a weak boundary layer.

PubMed

Majani, Ruby; Zelzer, Mischa; Gadegaard, Nikolaj; Rose, Felicity R; Alexander, Morgan R

2010-09-01

The use of cell sheets for tissue engineering applications has considerable advantages over single cell seeding techniques. So far, only thermoresponsive surfaces have been used to manufacture cell sheets without chemically disrupting the cell-surface interactions. Here, we present a new and facile technique to prepare sheets of epithelial cells using plasma polymerised acrylic acid films. The cell sheets are harvested by gentle agitation of the media without the need of any additional external stimulus. We demonstrate that the plasma polymer deposition conditions affect the viability and metabolic activity of the cells in the sheet and relate these effects to the different surface properties of the plasma polymerised acrylic acid films. Based on surface analysis data, a first attempt is made to explain the mechanism behind the cell sheet formation. The advantage of the epithelial cell sheets generated here over single cell suspensions to seed a PLGA scaffold is presented. The scaffold itself, prepared using a mould fabricated via photolithography, exhibits a unique architecture that mimics closely the dimensions of the native tissue (mouse intestine). Copyright 2010 Elsevier Ltd. All rights reserved.

Towards a better understanding of high-energy electron pitch-angle scattering by electromagnetic ion cyclotron waves

NASA Astrophysics Data System (ADS)

Vincena, S.; Gekelman, W.; Pribyl, P.; Tang, S., W.,; Papadopoulos, K.

2017-10-01

Shear Alfven waves are a fundamental mode in magnetized plasmas. Propagating near the ion cyclotron frequency, these waves are often termed electromagnetic ion cyclotron (EMIC) waves and can involve multiple ion species. Near the earth, for example, the wave may interact resonantly with oxygen ions at altitudes ranging from 1000 to 2000 km. The waves may either propagate from space towards the earth (possibly involving mode conversion), or be generated by RF transmitters on the ground. These preliminary experiments are motivated by theoretical predictions that such waves can pitch-angle scatter relativistic electrons trapped in the earth's dipole field. EMIC waves are launched in the Large Plasma Device at UCLA's Basic Plasma Science Facility in plasmas with single and multiple ion species into magnetic field gradients where ion cyclotron resonance is satisfied. We report here on the frequency and k-spectra in the critical layer and how they compare with theoretical predictions in computing an effective diffusion coefficient for high-energy electrons. Funding is provided by the NSF, DoE, and AFSOR.

Measurements of Magnetic Helicity within Two Interacting Flux Ropes

NASA Astrophysics Data System (ADS)

Dehaas, Timothy; Gekelman, Walter

2016-10-01

Magnetic helicity (HM) has become a useful tool in the exploration of astrophysical plasmas. Its conservation in the MHD limit (and even some fluid approaches) constrains the global behavior of large plasma structures. One such astrophysical structure is a magnetic flux rope: a rope-like, current-carrying plasma embedded in an external magnetic field. Bundles of these ropes are commonly observed extending from the solar surface and can be found in the near-earth environment. In this well-diagnosed experiment (3D measurements of ne, Te, Vp, B, J, E, uflow) , two magnetic flux ropes were generated in the Large Plasma Device at UCLA. These ropes were driven kink-unstable, commencing complex motion. As they interact, helicity conservation is broken in regions of reconnection, turbulence, and instabilities. The changes in helicity can be visualized as 1) the transport of helicity (ϕB +E × A) and 2) the dissipation of the helicity (-2EB). Magnetic helicity is observed to have a negative sign and its counterpart, cross helicity, a positive one. These qualities oscillate 8% peak-to-peak. As the ropes move and the topology of the field lines change, a quasi-separatrix layer (QSL) is formed. The volume averaged HM and the largest value of Q both oscillate but not in phase. In addition to magnetic helicity, similar quantities such as self-helicity, mutual-helicity, vorticity, and canonical helicity are derived and will be presented. This work is supported by LANL-UC research Grant and done at the Basic Plasma Science Facility, which is funded by DOE and NSF.

Plasma-wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

NASA Astrophysics Data System (ADS)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; Schmid, K.; Kirschner, A.; Hakola, A.; Tabares, F. L.; van der Meiden, H. J.; Mayoral, M.-L.; Reinhart, M.; Tsitrone, E.; Ahlgren, T.; Aints, M.; Airila, M.; Almaviva, S.; Alves, E.; Angot, T.; Anita, V.; Arredondo Parra, R.; Aumayr, F.; Balden, M.; Bauer, J.; Ben Yaala, M.; Berger, B. M.; Bisson, R.; Björkas, C.; Bogdanovic Radovic, I.; Borodin, D.; Bucalossi, J.; Butikova, J.; Butoi, B.; Čadež, I.; Caniello, R.; Caneve, L.; Cartry, G.; Catarino, N.; Čekada, M.; Ciraolo, G.; Ciupinski, L.; Colao, F.; Corre, Y.; Costin, C.; Craciunescu, T.; Cremona, A.; De Angeli, M.; de Castro, A.; Dejarnac, R.; Dellasega, D.; Dinca, P.; Dittmar, T.; Dobrea, C.; Hansen, P.; Drenik, A.; Eich, T.; Elgeti, S.; Falie, D.; Fedorczak, N.; Ferro, Y.; Fornal, T.; Fortuna-Zalesna, E.; Gao, L.; Gasior, P.; Gherendi, M.; Ghezzi, F.; Gosar, Ž.; Greuner, H.; Grigore, E.; Grisolia, C.; Groth, M.; Gruca, M.; Grzonka, J.; Gunn, J. P.; Hassouni, K.; Heinola, K.; Höschen, T.; Huber, S.; Jacob, W.; Jepu, I.; Jiang, X.; Jogi, I.; Kaiser, A.; Karhunen, J.; Kelemen, M.; Köppen, M.; Koslowski, H. R.; Kreter, A.; Kubkowska, M.; Laan, M.; Laguardia, L.; Lahtinen, A.; Lasa, A.; Lazic, V.; Lemahieu, N.; Likonen, J.; Linke, J.; Litnovsky, A.; Linsmeier, Ch.; Loewenhoff, T.; Lungu, C.; Lungu, M.; Maddaluno, G.; Maier, H.; Makkonen, T.; Manhard, A.; Marandet, Y.; Markelj, S.; Marot, L.; Martin, C.; Martin-Rojo, A. B.; Martynova, Y.; Mateus, R.; Matveev, D.; Mayer, M.; Meisl, G.; Mellet, N.; Michau, A.; Miettunen, J.; Möller, S.; Morgan, T. W.; Mougenot, J.; Mozetič, M.; Nemanič, V.; Neu, R.; Nordlund, K.; Oberkofler, M.; Oyarzabal, E.; Panjan, M.; Pardanaud, C.; Paris, P.; Passoni, M.; Pegourie, B.; Pelicon, P.; Petersson, P.; Piip, K.; Pintsuk, G.; Pompilian, G. O.; Popa, G.; Porosnicu, C.; Primc, G.; Probst, M.; Räisänen, J.; Rasinski, M.; Ratynskaia, S.; Reiser, D.; Ricci, D.; Richou, M.; Riesch, J.; Riva, G.; Rosinski, M.; Roubin, P.; Rubel, M.; Ruset, C.; Safi, E.; Sergienko, G.; Siketic, Z.; Sima, A.; Spilker, B.; Stadlmayr, R.; Steudel, I.; Ström, P.; Tadic, T.; Tafalla, D.; Tale, I.; Terentyev, D.; Terra, A.; Tiron, V.; Tiseanu, I.; Tolias, P.; Tskhakaya, D.; Uccello, A.; Unterberg, B.; Uytdenhoven, I.; Vassallo, E.; Vavpetič, P.; Veis, P.; Velicu, I. L.; Vernimmen, J. W. M.; Voitkans, A.; von Toussaint, U.; Weckmann, A.; Wirtz, M.; Založnik, A.; Zaplotnik, R.; PFC contributors, WP

2017-11-01

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.

Charged Particle lunar Environment Experiment (CPLEE)

NASA Technical Reports Server (NTRS)

Reasoner, D. L.

1974-01-01

Research development in the Charged Particle Lunar Environment Experiment (CPLEE) is reported. The CPLEE is ion-electron spectrometer placed on the lunar surface for the purpose of measuring charged particle fluxes impacting the moon from a variety of regions and to study the interactions between space plasmas and the lunar surface. The principal accomplishments reported include: (1) furnishing design specifications for construction of the CPLEE instruments; (2) development of an advanced computer-controlled facility for automated instrument calibration; (3) active participation in the deployment and past-deployment operational phases with regard to data verification and operational mode selection; and (4) publication of research papers, including a study of lunar photoelectrons, a study of plasmas resulting from man-made lunar impart events, a study of magnetotail and magnetosheath particle populations, and a study of solar-flare interplanetary particles.

Critical need for MFE: the Alcator DX advanced divertor test facility

NASA Astrophysics Data System (ADS)

Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Wolf, S.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hutchinson, I.; Hubbard, A.; Hughes, J.; Lin, Y.; Lipschultz, B.; Parker, R.; Porkolab, M.; Reinke, M.; Rice, J.; Shiraiwa, S.; Terry, J.; Theiler, C.; Wallace, G.; White, A.; Whyte, D.; Wukitch, S.

2013-10-01

Three critical challenges must be met before a steady-state, power-producing fusion reactor can be realized: how to (1) safely handle extreme plasma exhaust power, (2) completely suppress material erosion at divertor targets and (3) do this while maintaining a burning plasma core. Advanced divertors such as ``Super X'' and ``X-point target'' may allow a fully detached, low temperature plasma to be produced in the divertor while maintaining a hot boundary layer around a clean plasma core - a potential game-changer for magnetic fusion. No facility currently exists to test these ideas at the required parallel heat flux densities. Alcator DX will be a national facility, employing the high magnetic field technology of Alcator combined with high-power ICRH and LHCD to test advanced divertor concepts at FNSF/DEMO power exhaust densities and plasma pressures. Its extended vacuum vessel contains divertor cassettes with poloidal field coils for conventional, snowflake, super-X and X-point target geometries. Divertor and core plasma performance will be explored in regimes inaccessible in conventional devices. Reactor relevant ICRF and LH drivers will be developed, utilizing high-field side launch platforms for low PMI. Alcator DX will inform the conceptual development and accelerate the readiness-for-deployment of next-step fusion facilities.

Studies of RF sheaths and diagnostics on IShTAR

NASA Astrophysics Data System (ADS)

Crombé, K.; Devaux, S.; D'Inca, R.; Faudot, E.; Faugel, H.; Fünfgelder, H.; Heuraux, S.; Jacquot, J.; Louche, F.; Moritz, J.; Ochoukov, R.; Tripsky, M.; Van Eester, D.; Wauters, T.; Noterdaeme, J.-M.

2015-12-01

IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed to excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.

A recoverable gas-cell diagnostic for the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ratkiewicz, A., E-mail: ratkiewicz1@llnl.gov; Berzak Hopkins, L.; Bleuel, D. L.

2016-11-15

The high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of {sup nat}Xemore » and discuss future work to study the strength of interactions between plasma and nuclei.« less

A recoverable gas-cell diagnostic for the National Ignition Facility

DOE PAGES

Ratkiewicz, A.; Hopkins, L. Berzak; Bleuel, D. L.; ...

2016-08-22

Here, the high-fluence neutron spectrum produced by the National Ignition Facility (NIF) provides an opportunity to measure the activation of materials by fast-spectrum neutrons. A new large-volume gas-cell diagnostic has been designed and qualified to measure the activation of gaseous substances at the NIF. This in-chamber diagnostic is recoverable, reusable and has been successfully fielded. Data from the qualification of the diagnostic have been used to benchmark an Monte Carlo N-Particle Transport Code simulation describing the downscattered neutron spectrum seen by the gas cell. We present early results from the use of this diagnostic to measure the activation of natXemore » and discuss future work to study the strength of interactions between plasma and nuclei.« less

Collisionless Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma

NASA Astrophysics Data System (ADS)

Bondarenko, Anton

2016-10-01

The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space phenomena, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these rarified environments, collective electromagnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collisionless coupling mechanisms in a reproducible laboratory setting, the present research jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA to study the super-Alfvénic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field induction probes. Large Doppler shifts detected in a He II ion spectral line directly indicate initial ambient ion acceleration transverse to both the debris plasma flow and the background magnetic field, indicative of a fundamental process known as Larmor coupling. Characterization of the laser-produced debris plasma via a radiation-hydrodynamics code permits an explicit calculation of the laminar electric field in the framework of a ``hybrid'' model (kinetic ions, charge-neutralizing massless fluid electrons), thus allowing for a simulation of the initial response of a distribution of He II test ions. A synthetic Doppler-shifted spectrum constructed from the simulated velocity distribution of the accelerated test ions excellently reproduces the spectroscopic measurements, confirming the role of Larmor coupling in the debris-ambient interaction.

Dense Plasma Focus: physics and applications (radiation material science, single-shot disclosure of hidden illegal objects, radiation biology and medicine, etc.)

NASA Astrophysics Data System (ADS)

Gribkov, V. A.; Miklaszewski, R.; Paduch, M.; Zielinska, E.; Chernyshova, M.; Pisarczyk, T.; Pimenov, V. N.; Demina, E. V.; Niemela, J.; Crespo, M.-L.; Cicuttin, A.; Tomaszewski, K.; Sadowski, M. J.; Skladnik-Sadowska, E.; Pytel, K.; Zawadka, A.; Giannini, G.; Longo, F.; Talab, A.; Ul'yanenko, S. E.

2015-03-01

The paper presents some outcomes obtained during the year of 2013 of the activity in the frame of the International Atomic Energy Agency Co-ordinated research project "Investigations of Materials under High Repetition and Intense Fusion-Relevant Pulses". The main results are related to the effects created at the interaction of powerful pulses of different types of radiation (soft and hard X-rays, hot plasma and fast ion streams, neutrons, etc. generated in Dense Plasma Focus (DPF) facilities) with various materials including those that are counted as perspective ones for their use in future thermonuclear reactors. Besides we discuss phenomena observed at the irradiation of biological test objects. We examine possible applications of nanosecond powerful pulses of neutrons to the aims of nuclear medicine and for disclosure of hidden illegal objects. Special attention is devoted to discussions of a possibility to create extremely large and enormously diminutive DPF devices and probabilities of their use in energetics, medicine and modern electronics.

Experimental Evidence of Kinetic Effects in Indirect-Drive Inertial Confinement Fusion Hohlraums

NASA Astrophysics Data System (ADS)

Shan, L. Q.; Cai, H. B.; Zhang, W. S.; Tang, Q.; Zhang, F.; Song, Z. F.; Bi, B.; Ge, F. J.; Chen, J. B.; Liu, D. X.; Wang, W. W.; Yang, Z. H.; Qi, W.; Tian, C.; Yuan, Z. Q.; Zhang, B.; Yang, L.; Jiao, J. L.; Cui, B.; Zhou, W. M.; Cao, L. F.; Zhou, C. T.; Gu, Y. Q.; Zhang, B. H.; Zhu, S. P.; He, X. T.

2018-05-01

We present the first experimental evidence supported by simulations of kinetic effects launched in the interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona plasma of the compressed pellet at the Shenguang-III prototype laser facility. Solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron yield is quenched, DD fusion yield from the corona plasma provides a direct measure of the kinetic effects inside the hohlraum. An anomalous large energy spread of the DD neutron signal (˜282 keV ) and anomalous scaling of the neutron yield with the thickness of the carbon-deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these results can be attributed to kinetic shocks that arise in the hohlraum-wall-ablator interpenetration region, which result in efficient acceleration of the deuterons (˜28.8 J , 0.45% of the total input laser energy). These studies provide novel insight into the interactions and dynamics of a vacuum hohlraum and near-vacuum hohlraum.

A Burning Plasma Experiment: the role of international collaboration

NASA Astrophysics Data System (ADS)

Prager, Stewart

2003-04-01

The world effort to develop fusion energy is at the threshold of a new stage in its research: the investigation of burning plasmas. A burning plasma is self-heated. The 100 million degree temperature of the plasma is maintained by the heat generated by the fusion reactions themselves, as occurs in burning stars. The fusion-generated alpha particles produce new physical phenomena that are strongly coupled together as a nonlinear complex system, posing a major plasma physics challenge. Two attractive options are being considered by the US fusion community as burning plasma facilities: the international ITER experiment and the US-based FIRE experiment. ITER (the International Thermonuclear Experimental Reactor) is a large, power-plant scale facility. It was conceived and designed by a partnership of the European Union, Japan, the Soviet Union, and the United States. At the completion of the first engineering design in 1998, the US discontinued its participation. FIRE (the Fusion Ignition Research Experiment) is a smaller, domestic facility that is at an advanced pre-conceptual design stage. Each facility has different scientific, programmatic and political implications. Selecting the optimal path for burning plasma science is itself a challenge. Recently, the Fusion Energy Sciences Advisory Committee recommended a dual path strategy in which the US seek to rejoin ITER, but be prepared to move forward with FIRE if the ITER negotiations do not reach fruition by July, 2004. Either the ITER or FIRE experiment would reveal the behavior of burning plasmas, generate large amounts of fusion power, and be a huge step in establishing the potential of fusion energy to contribute to the world's energy security.

Simulation of Targets Feeding Pipe Rupture in Wendelstein 7-X Facility Using RELAP5 and COCOSYS Codes

NASA Astrophysics Data System (ADS)

Kaliatka, T.; Povilaitis, M.; Kaliatka, A.; Urbonavicius, E.

2012-10-01

Wendelstein nuclear fusion device W7-X is a stellarator type experimental device, developed by Max Planck Institute of plasma physics. Rupture of one of the 40 mm inner diameter coolant pipes providing water for the divertor targets during the "baking" regime of the facility operation is considered to be the most severe accident in terms of the plasma vessel pressurization. "Baking" regime is the regime of the facility operation during which plasma vessel structures are heated to the temperature acceptable for the plasma ignition in the vessel. This paper presents the model of W7-X cooling system (pumps, valves, pipes, hydro-accumulators, and heat exchangers), developed using thermal-hydraulic state-of-the-art RELAP5 Mod3.3 code, and model of plasma vessel, developed by employing the lumped-parameter code COCOSYS. Using both models the numerical simulation of processes in W7-X cooling system and plasma vessel has been performed. The results of simulation showed, that the automatic valve closure time 1 s is the most acceptable (no water hammer effect occurs) and selected area of the burst disk is sufficient to prevent pressure in the plasma vessel.

Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF.

PubMed

Döppner, T; Dewald, E L; Divol, L; Thomas, C A; Burns, S; Celliers, P M; Izumi, N; Kline, J L; LaCaille, G; McNaney, J M; Prasad, R R; Robey, H F; Glenzer, S H; Landen, O L

2012-10-01

We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.

Fast Ion and Thermal Plasma Transport in Turbulent Waves in the Large Plasma Device (LAPD)

NASA Astrophysics Data System (ADS)

Zhou, Shu

2011-10-01

The transport of fast ions and thermal plasmas in electrostatic microturbulence is studied. Strong density and potential fluctuations (δn / n ~ δϕ / kTe ~ 0 . 5 , f ~5-50 kHz) are observed in the LAPD in density gradient regions produced by obstacles with slab or cylindrical geometry. Wave characteristics and the associated plasma transport are modified by driving sheared E ×B drift through biasing the obstacle, and by modification of the axial magnetic fields (Bz) and the plasma species. Cross-field plasma transport is suppressed with small bias and large Bz, and is enhanced with large bias and small Bz. Suppressed cross-field thermal transport coincides with a 180° phase shift between the density and potential fluctuations in the radial direction, while the enhanced thermal transport is associated with modes having low mode number (m = 1) and long radial correlation length. Large gyroradius lithium ions (ρfast /ρs ~ 10) orbit through the turbulent region. Scans with a collimated analyzer and with Langmuir probes give detailed profiles of the fast ion spatial-temporal distribution and of the fluctuating fields. Fast-ion transport decreases rapidly with increasing fast-ion gyroradius. Background waves with different scale lengths also alter the fast ion transport: Beam diffusion is smaller in waves with smaller structures (higher mode number); also, coherent waves with long correlation length cause less beam diffusion than turbulent waves. Experimental results agree well with gyro-averaging theory. When the fast ion interacts with the wave for most of a wave period, a transition from super-diffusive to sub-diffusive transport is observed, as predicted by diffusion theory. A Monte Carlo trajectory-following code simulates the interaction of the fast ions with the measured turbulent fields. Good agreement between observation and modeling is observed. Work funded by DOE and NSF and performed at the Basic Plasma Science Facility.

An overview of research activities on materials for nuclear applications at the INL Safety, Tritium and Applied Research facility

NASA Astrophysics Data System (ADS)

Calderoni, P.; Sharpe, J.; Shimada, M.; Denny, B.; Pawelko, B.; Schuetz, S.; Longhurst, G.; Hatano, Y.; Hara, M.; Oya, Y.; Otsuka, T.; Katayama, K.; Konishi, S.; Noborio, K.; Yamamoto, Y.

2011-10-01

The Safety, Tritium and Applied Research facility at the Idaho National Laboratory is a US Department of Energy National User Facility engaged in various aspects of materials research for nuclear applications related to fusion and advanced fission systems. Research activities are mainly focused on the interaction of tritium with materials, in particular plasma facing components, liquid breeders, high temperature coolants, fuel cladding, cooling and blanket structures and heat exchangers. Other activities include validation and verification experiments in support of the Fusion Safety Program, such as beryllium dust reactivity and dust transport in vacuum vessels, and support of Advanced Test Reactor irradiation experiments. This paper presents an overview of the programs engaged in the activities, which include the US-Japan TITAN collaboration, the US ITER program, the Next Generation Power Plant program and the tritium production program, and a presentation of ongoing experiments as well as a summary of recent results with emphasis on fusion relevant materials.

ISS Plasma Interaction: Measurements and Modeling

NASA Technical Reports Server (NTRS)

Barsamian, H.; Mikatarian, R.; Alred, J.; Minow, J.; Koontz, S.

2004-01-01

Ionospheric plasma interaction effects on the International Space Station are discussed in the following paper. The large structure and high voltage arrays of the ISS represent a complex system interacting with LEO plasma. Discharge current measurements made by the Plasma Contactor Units and potential measurements made by the Floating Potential Probe delineate charging and magnetic induction effects on the ISS. Based on theoretical and physical understanding of the interaction phenomena, a model of ISS plasma interaction has been developed. The model includes magnetic induction effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. Based on these phenomena, the Plasma Interaction Model has been developed. Limited verification of the model has been performed by comparison of Floating Potential Probe measurement data to simulations. The ISS plasma interaction model will be further tested and verified as measurements from the Floating Potential Measurement Unit become available, and construction of the ISS continues.

Brilliant GeV gamma-ray flash from inverse Compton scattering in the QED regime

NASA Astrophysics Data System (ADS)

Gong, Z.; Hu, R. H.; Lu, H. Y.; Yu, J. Q.; Wang, D. H.; Fu, E. G.; Chen, C. E.; He, X. T.; Yan, X. Q.

2018-04-01

An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective ˜ 1023 W cm-2 laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 × 1023 photons s-1 mm-2 mrad-2/0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.

Description and Operation of the Mark 1B Plasma Focus Radiation Facility,

DTIC Science & Technology

plasma focus facility (Mk 1B) at The Aerospace Corporation produces x-ray fluences that are applicable to most radiation testing problems (e.g., integrated circuits or transistors). Although the facility has only one beryllium window for exposing 1.6-cm-dia samples to doses of 25 to 45 krad (Si) per shot, three more windows could be added and the additional samples exposed simultaneously. The facility is experiencing switch problems and is presently averaging 50 shots per week--15 shots per day for 3 or 4 days. The results of a comprehensive switch analysis should

ADX: a high field, high power density, Advanced Divertor test eXperiment

NASA Astrophysics Data System (ADS)

Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Shiraiwa, S.; Terry, J.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; ADX Team

2014-10-01

The MIT PSFC and collaborators are proposing an advanced divertor experiment (ADX) - a tokamak specifically designed to address critical gaps in the world fusion research program on the pathway to FNSF/DEMO. This high field (6.5 tesla, 1.5 MA), high power density (P/S ~ 1.5 MW/m2) facility would utilize Alcator magnet technology to test innovative divertor concepts for next-step DT fusion devices (FNSF, DEMO) at reactor-level boundary plasma pressures and parallel heat flux densities while producing high performance core plasma conditions. The experimental platform would also test advanced lower hybrid current drive (LHCD) and ion-cyclotron range of frequency (ICRF) actuators and wave physics at the plasma densities and magnetic field strengths of a DEMO, with the unique ability to deploy launcher structures both on the low-magnetic-field side and the high-field side - a location where energetic plasma-material interactions can be controlled and wave physics is most favorable for efficient current drive, heating and flow drive. This innovative experiment would perform plasma science and technology R&D necessary to inform the conceptual development and accelerate the readiness-for-deployment of FNSF/DEMO - in a timely manner, on a cost-effective research platform. Supported by DE-FC02-99ER54512.

Operation of the ORNL High Particle Flux Helicon Plasma Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goulding, R. H.; Biewer, T. M.; Caughman, J. B. O.

2011-12-23

A high power, high particle flux rf-based helicon plasma source has been constructed at ORNL and operated at power levels up to 30 kW. High-density hydrogen and helium plasmas have been produced. The source has been designed as the basis for a linear plasma materials interaction (PMI) test facility that will generate particle fluxes {Gamma}{sub p}10{sup 23} m{sup -3} s{sup -1}, and utilize additional ion and electron cyclotron heating to produce high parallel (to the magnetic field) heat fluxes of {approx}10 MW/m{sup 2}. An rf-based source for PMI research is of interest because high plasma densities are generated with nomore » internal electrodes, allowing true steady state operation with minimal impurity generation. The ORNL helicon source has a diameter of 15 cm and to-date has operated at a frequency f = 13.56 MHz, with magnetic field strength |B| in the antenna region up to {approx}0.15 T. Maximum densities of 3x10{sup 19} m{sup -3} in He and 2.5x10{sup 19} m{sup -3} in H have been achieved. Radial density profiles have been seen to be dependent on the axial |B| profile.« less

Operation of the ORNL High Particle Flux Helicon Plasma Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goulding, Richard Howell; Biewer, Theodore M; Caughman, John B

2011-01-01

A high power, high particle flux rf-based helicon plasma source has been constructed at ORNL and operated at power levels up to 30 kW. High-density hydrogen and helium plasmas have been produced. The source has been designed as the basis for a linear plasma materials interaction (PMI) test facility that will generate particle fluxes Gamma(p) > 10(23) M-3 s(-1), and utilize additional ion and electron cyclotron heating to produce high parallel (to the magnetic field) heat fluxes of similar to 10 MW/m(2). An rf-based source for PMI research is of interest because high plasma densities are generated with no internalmore » electrodes, allowing true steady state operation with minimal impurity generation. The ORNL helicon source has a diameter of 15 cm and to-date has operated at a frequency f = 13.56 MHz, with magnetic field strength vertical bar B vertical bar in the antenna region up to similar to 0.15 T. Maximum densities of 3 x 10(19) M-3 in He and 2.5 x 10(19) m(-3) in H have been achieved. Radial density profiles have been seen to be dependent on the axial vertical bar B vertical bar profile.« less

Simulations of ultrafast x-ray laser experiments

NASA Astrophysics Data System (ADS)

Fortmann-Grote, C.; Andreev, A. A.; Appel, K.; Branco, J.; Briggs, R.; Bussmann, M.; Buzmakov, A.; Garten, M.; Grund, A.; Huebl, A.; Jurek, Z.; Loh, N. D.; Nakatsutsumi, M.; Samoylova, L.; Santra, R.; Schneidmiller, E. A.; Sharma, A.; Steiniger, K.; Yakubov, S.; Yoon, C. H.; Yurkov, M. V.; Zastrau, U.; Ziaja-Motyka, B.; Mancuso, A. P.

2017-06-01

Simulations of experiments at modern light sources, such as optical laser laboratories, synchrotrons, and free electron lasers, become increasingly important for the successful preparation, execution, and analysis of these experiments investigating ever more complex physical systems, e.g. biomolecules, complex materials, and ultra-short lived states of matter at extreme conditions. We have implemented a platform for complete start-to-end simulations of various types of photon science experiments, tracking the radiation from the source through the beam transport optics to the sample or target under investigation, its interaction with and scattering from the sample, and registration in a photon detector. This tool allows researchers and facility operators to simulate their experiments and instruments under real life conditions, identify promising and unattainable regions of the parameter space and ultimately make better use of valuable beamtime. In this paper, we present an overview about status and future development of the simulation platform and discuss three applications: 1.) Single-particle imaging of biomolecules using x-ray free electron lasers and optimization of x-ray pulse properties, 2.) x-ray scattering diagnostics of hot dense plasmas in high power laser-matter interaction and identification of plasma instabilities, and 3.) x-ray absorption spectroscopy in warm dense matter created by high energy laser-matter interaction and pulse shape optimization for low-isentrope dynamic compression.

Experimental Simulation of Solar Wind Interaction with MagneticDipole Fields above Insulating Surfaces

NASA Astrophysics Data System (ADS)

Yeo, L. H.; Han, J.; Wang, X.; Werner, G.; Deca, J.; Munsat, T.; Horanyi, M.

2017-12-01

Magnetic anomalies on the surfaces of airless bodies such as the Moon interact with the solar wind, resulting in both magnetic and electrostatic deflection/reflection of thecharged particles. Consequently, surface charging in these regions will be modified. Using the Colorado Solar Wind Experiment facility, this interaction is investigated with high-energy flowing plasmas (100-800 eV beam ions) that are incident upon a magnetic dipole (0.13 T) embedded under various insulating surfaces. The dipole moment is perpendicular to the surface. Using an emissive probe, 2D plasma potential profiles are obtained above the surface. In the dipole lobe regions, the surfaces are charged to significantly positive potentials due to the impingement of the unmagnetized ions while the electrons are magnetically shielded. At low ion beam energies, the results agree with the theoretical predictions, i.e., the surface potential follows the energy of the beam ions in eV. However, at high energies, the surface potentials in the electron-shielded regions are significantly lower than the beam energies. A series of investigations have been conducted and indicate that the surface properties (e.g., modified surface conductance, ion induced secondary electrons and electron-neutral collision at the surface) are likely to play a role in determining the surface potential.

Studies of RF sheaths and diagnostics on IShTAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crombé, K., E-mail: Kristel.Crombe@UGent.be; LPP-ERM/KMS, Royal Military Academy, Brussels; Devaux, S.

2015-12-10

IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed tomore » excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.« less

Reinforced carbon-carbon oxidation behavior in convective and radiative environments

NASA Technical Reports Server (NTRS)

Curry, D. M.; Johansen, K. J.; Stephens, E. W.

1978-01-01

Reinforced carbon-carbon, which is used as thermal protection on the space shuttle orbiter wing leading edges and nose cap, was tested in both radiant and plasma arcjet heating test facilities. The test series was conducted at varying temperatures and pressures. Samples tested in the plasma arcjet facility had consistently higher mass loss than those samples tested in the radiant facility. A method using the mass loss data is suggested for predicting mission mass loss for specific locations on the Orbiter.

Tornado-like transport in a magnetized plasma

NASA Astrophysics Data System (ADS)

Poulos, Matthew; van Compernolle, Bart; Morales, George

2017-10-01

Recent heat transport experiments conducted in the LAPD device at UCLA in which avalanche events have been previously documented have also lead to the identification of a new tornado-like transport phenomenon. These tornados occur much earlier than the avalanches events, essentially in the interval following the application of the bias voltage that causes the injection of an electron beam from a ring-shaped LaB6 cathode into the afterglow of a cold, magnetized plasma. The tornados exhibit a low-frequency (4 kHz) (much lower than drift-waves), spiraling, global eigenmode whose transient behavior is responsible for significant radial transport well outside the heated region. Detailed experimental observations are compared with a Braginskii transport code that includes the effects of ExB convection induced by the spiraling global eigenmode. New insights are gained into the necessary modifications of classical transport to accurately simulate the spiraling effects and the possible interaction with avalanches. This work is supported by the NSF/DOE partnership in basic plasma science and engineering, Grant Number 1619505, and is performed at the Basic Plasma Science Facility, sponsored jointly by DOE and NSF. Sponsored by DOE/NSF at BaPSF and NSF 1619505.

Extreme plasma states in laser-governed vacuum breakdown.

PubMed

Efimenko, Evgeny S; Bashinov, Aleksei V; Bastrakov, Sergei I; Gonoskov, Arkady A; Muraviev, Alexander A; Meyerov, Iosif B; Kim, Arkady V; Sergeev, Alexander M

2018-02-05

Triggering vacuum breakdown at laser facility is expected to provide rapid electron-positron pair production for studies in laboratory astrophysics and fundamental physics. However, the density of the produced plasma may cease to increase at a relativistic critical density, when the plasma becomes opaque. Here, we identify the opportunity of breaking this limit using optimal beam configuration of petawatt-class lasers. Tightly focused laser fields allow generating plasma in a small focal volume much less than λ 3 and creating extreme plasma states in terms of density and produced currents. These states can be regarded to be a new object of nonlinear plasma physics. Using 3D QED-PIC simulations we demonstrate a possibility of reaching densities over 10 25  cm -3 , which is an order of magnitude higher than expected earlier. Controlling the process via initial target parameters provides an opportunity to reach the discovered plasma states at the upcoming laser facilities.

A tandem mirror hybrid plume plasma propulsion facility

NASA Technical Reports Server (NTRS)

Yang, T. F.; Krueger, W. A.; Peng, S.; Urbahn, J.; Chang-Diaz, F. R.

1988-01-01

This paper discusses a novel concept in electrodeless plasma propulsion, in which the materials problems are ameliorated by an electrodeless magnetic confinement scheme borrowed from the tandem mirror approach to controlled thermonuclear fusion. The concept also features a two-stage magnetic nozzle with an annular hypersonic coaxial gas injector near the throat. The nozzle produces hybrid plume by the coaxial injection of hypersonic neutral gas, and the gas layer thus formed protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The tandem mirror plasma propulsion facility is capable of delivering a variable I(sp). The results of numerical simulation of this concept are presented together with those from an experimental tandem-mirror plasma propulsion device.

Characterization of the Inductively Heated Plasma Source IPG6-B

NASA Astrophysics Data System (ADS)

Dropmann, Michael; Laufer, Rene; Herdrich, Georg; Matthews, Lorin; Hyde, Truell

2014-10-01

In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma facilities have been established using the Inductively heated Plasma Generator 6 (IPG6). The facility at Baylor University (IPG6-B) works at a frequency of 13.56 MHz and a maximum power of 15 kW. A vacuum pump of 160 m3/h in combination with a butterfly valve allows pressure control over a wide range. Intended fields of research include basic investigation into thermo-chemistry and plasma radiation, space plasma environments and high heat fluxes e.g. those found in fusion devices or during atmospheric re-entry of spacecraft. After moving the IPG6-B facility to the Baylor Research and Innovation Collaborative (BRIC) it was placed back into operation during the summer of 2014. Initial characterization in the new lab, using a heat flux probe, Pitot probe and cavity calorimeter, has been conducted for Air, Argon and Helium. The results of this characterization are presented.

Final Technical Report: Magnetic Reconnection in High-Energy Laser-Produced Plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Germaschewski, Kai; Fox, William; Bhattacharjee, Amitava

This report describes the final results from the DOE Grant DE-SC0007168, “Fast Magnetic Reconnection in HED Laser-Produced Plasmas.” The recent generation of laboratory high-energy-density physics facilities has opened significant physics opportunities for experimentally modeling astrophysical plasmas. The goal of this proposal is to use these new tools to study fundamental problems in plasma physics and plasma astrophysics. Fundamental topics in this area involve study of the generation, amplification, and fate of magnetic fields, which are observed to pervade the plasma universe and govern its evolution. This project combined experiments at DOE laser facilities with kinetic plasma simulation to study thesemore » processes. The primary original goal of the project was to study magnetic reconnection using a new experimental platform, colliding magnetized laser-produced plasmas. However through a series of fortuitous discoveries, the work broadened out to allow significant advancement on multiple topics in laboratory astrophysics, including magnetic reconnection, Weibel instability, and collisionless shocks.« less

Optimisation of parameters of Raman laser pulse compression in a plasma for its implementation using the PEARL laser facility (IAP RAS)

NASA Astrophysics Data System (ADS)

Balakin, A. A.; Levin, D. S.; Skobelev, S. A.

2018-04-01

We consider Raman compression of laser pulses in a plasma under the conditions of an experiment planned at the Institute of Applied Physics of the Russian Academy of Sciences on the PEARL laser facility. The analysis is based on the equations describing, among other things, the effect of plasma dispersion and relativistic nonlinearity, as well as the dynamics of the field near the plasma wave breaking threshold. It is shown that the main limiting factors are excessive frequency modulation of the pump pulse and a too low plasma density in which the plasma wave breaking can occur. To reduce the negative influence of these effects, we suggest using an intense and short (on the order of the plasma period) seed laser pulse. Numerical simulation shows the possibility of a hundredfold increase in the intensity of the compressed pulse in comparison with the intensity of the pump pulse at a length of uniform plasma of 2 cm.

Preliminary studies for a beam-generated plasma neutralizer test in NIO1

NASA Astrophysics Data System (ADS)

Sartori, E.; Veltri, P.; Balbinot, L.; Cavenago, M.; Veranda, M.; Antoni, V.; Serianni, G.

2017-08-01

The deployment of neutral beam injectors in future fusion plants is beset by the particularly poor efficiency of the neutralization process. Beam-generated plasma neutralizers were proposed as a passive and intrinsically safe scheme of efficient plasma neutralizers. The concept is based on the natural ionization of the gas target by the beam, and on a suitable confinement of the secondary plasma. The technological challenge of such a concept is the magnetic confinement of the secondary plasma: a proof-of-principle for the concept is needed. The possibility to test of such a system in the small negative ion beam system NIO1 is discussed in this paper. The constraints given by the facility are first discussed. A model of beam-gas interaction is developed to provide the charge-state of beam particles along the neutralizer, and to provide the source terms of plasma generation. By using a cylindrical model of plasma diffusion in magnetic fields, the ionization degree of the target is estimated. In the absence of magnetic fields the diffusion model is validated against experimental measurements of the space-charge compensation plasma in the drift region of NIO1. Finally, the feasibility study for a beam-generated plasma neutralizer in NIO is presented. The neutralizer length, required gas target thickness, and a very simple magnetic setup were considered, taking into account the integration in NIO1. For the basic design a low ionization degree (1%) is obtained, however a promising plasma density up to hundred times the beam density was calculated. The proposed test in NIO1 can be the starting point for studying advanced schemes of magnetic confinement aiming at ionization degrees in the order of 10%.

Promoting Pre-college Science Education

NASA Astrophysics Data System (ADS)

Lee, R. L.

1999-11-01

The Fusion Education Program, with support from DOE, continues to promote pre-college science education for students and teachers using multiple approaches. An important part of our program is direct scientist-student interaction. Our ``Scientist in a Classroom'' program allows students to interact with scientists and engage in plasma science activities in the students' classroom. More than 1000 students from 11 schools have participated in this exciting program. Also, this year more than 800 students and teachers have visited the DIII--D facility and interacted with scientists to cover a broad range of technical and educational issues. Teacher-scientist interaction is imperative in professional development and each year more than 100 teachers attend workshops produced by the fusion education team. We also participate in unique learning opportunities. Members of the team, in collaboration with the San Diego County Office of Education, held a pioneering Internet-based Physics Olympiad for American and Siberian students. Our teamwork with educators helps shape material that is grade appropriate, relevant, and stimulates thinking in educators and students.

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE PAGES

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.; ...

2017-06-14

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less

Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brezinsek, S.; Coenen, J. W.; Schwarz-Selinger, T.

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, andmore » by modelling codes that simulate edge-plasma conditions and the plasma–material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.« less

The Dartmouth Elephant plasma facility

NASA Astrophysics Data System (ADS)

Lynch, K. A.

2017-12-01

The Elephant facility in the Dartmouth Dept of Physics and Astronomyis a 1m by 2m chamber with a microwave-resonant plasma source togetherwith a higher energy electron/ion electrostatic gun. In this chamber weaim to re-create features of the auroral ionosphere including both thethermal plasma background, and the precipitating energetic auroral beam.We can manipulate the position and attitude of various sensors withinthe chamber and monitor their response to the various sources. Recentefforts have focussed on the sheath environment near and around thermalion RPA sensors and the small payloads which carry them into theionosphere.

Analysis of the X-ray emission spectra of copper, germanium and rubidium plasmas produced at the Phelix laser facility

NASA Astrophysics Data System (ADS)

Comet, M.; Pain, J.-C.; Gilleron, F.; Piron, R.; Denis-Petit, D.; Méot, V.; Gosselin, G.; Morel, P.; Hannachi, F.; Gobet, F.; Tarisien, M.; Versteegen, M.

2017-03-01

We present the analysis of X-ray emission spectra of copper, germanium and rubidium plasmas measured at the Phelix laser facility. The laser intensity was around 6×1014 W.cm-2. The analysis is based on the hypothesis of an homogeneous plasma in local thermodynamic equilibrium using an effective temperature. This temperature is deduced from hydrodynamic simulations and collisional-radiative computations. Spectra are then calculated using the LTE opacity codes OPAMCDF and SCO-RCG and compared to experimental data.

Laser-plasma interactions and implosion symmetry in rugby hohlraums

NASA Astrophysics Data System (ADS)

Michel, Pierre; Berger, R. L.; Lasinski, B. F.; Ross, J. S.; Divol, L.; Williams, E. A.; Meeker, D.; Langdon, B. A.; Park, H.; Amendt, P.

2011-10-01

Cross-beam energy transfer is studied in the context of ``rugby''-hohlraum experiments at the Omega laser facility in FY11, in preparation for future NIF experiments. The transfer acts in opposite direction between rugby and cylinder hohlraums due to the different beam pointing geometries and flow patterns. Its interaction with backscatter is also different as both happen in similar regions inside rugby hohlraums. We will analyze the effects of non-linearities and temporal beam smoothing on energy transfer using the code pF3d. Calculations will be compared to experiments at Omega; analysis of future rugby hohlraum experiments on NIF will also be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Early Changes in Clinical, Functional, and Laboratory Biomarkers in Workers at Risk of Indium Lung Disease

PubMed Central

Virji, M. Abbas; Trapnell, Bruce C.; Carey, Brenna; Healey, Terrance; Kreiss, Kathleen

2014-01-01

Rationale: Occupational exposure to indium compounds, including indium–tin oxide, can result in potentially fatal indium lung disease. However, the early effects of exposure on the lungs are not well understood. Objectives: To determine the relationship between short-term occupational exposures to indium compounds and the development of early lung abnormalities. Methods: Among indium–tin oxide production and reclamation facility workers, we measured plasma indium, respiratory symptoms, pulmonary function, chest computed tomography, and serum biomarkers of lung disease. Relationships between plasma indium concentration and health outcome variables were evaluated using restricted cubic spline and linear regression models. Measurements and Main Results: Eighty-seven (93%) of 94 indium–tin oxide facility workers (median tenure, 2 yr; median plasma indium, 1.0 μg/l) participated in the study. Spirometric abnormalities were not increased compared with the general population, and few subjects had radiographic evidence of alveolar proteinosis (n = 0), fibrosis (n = 2), or emphysema (n = 4). However, in internal comparisons, participants with plasma indium concentrations ≥ 1.0 μg/l had more dyspnea, lower mean FEV1 and FVC, and higher median serum Krebs von den Lungen-6 and surfactant protein-D levels. Spline regression demonstrated nonlinear exposure response, with significant differences occurring at plasma indium concentrations as low as 1.0 μg/l compared with the reference. Associations between health outcomes and the natural log of plasma indium concentration were evident in linear regression models. Associations were not explained by age, smoking status, facility tenure, or prior occupational exposures. Conclusions: In indium–tin oxide facility workers with short-term, low-level exposure, plasma indium concentrations lower than previously reported were associated with lung symptoms, decreased spirometric parameters, and increased serum biomarkers of lung disease. PMID:25295756

PANDORA, a new facility for interdisciplinary in-plasma physics

NASA Astrophysics Data System (ADS)

Mascali, D.; Musumarra, A.; Leone, F.; Romano, F. P.; Galatà, A.; Gammino, S.; Massimi, C.

2017-07-01

PANDORA, Plasmas for Astrophysics, Nuclear Decays Observation and Radiation for Archaeometry, is planned as a new facility based on a state-of-the-art plasma trap confining energetic plasma for performing interdisciplinary research in the fields of Nuclear Astrophysics, Astrophysics, Plasma Physics and Applications in Material Science and Archaeometry: the plasmas become the environment for measuring, for the first time, nuclear decay rates in stellar-like condition (such as 7Be decay and beta-decay involved in s-process nucleosynthesis), especially as a function of the ionization state of the plasma ions. These studies will give important contributions for addressing several astrophysical issues in both stellar and primordial nucleosynthesis environment ( e.g., determination of solar neutrino flux and 7Li Cosmological Problem), moreover the confined energetic plasma will be a unique light source for high-performance stellar spectroscopy measurements in the visible, UV and X-ray domains, offering advancements in observational astronomy. As to magnetic fields, the experimental validation of theoretical first- and second-order Landé factors will drive the layout of next-generation polarimetric units for the high-resolution spectrograph of the future giant telescopes. In PANDORA new plasma heating methods will be explored, that will push forward the ion beam output, in terms of extracted intensity and charge states. More, advanced and optimized injection methods of ions in an ECR plasma will be experimented, with the aim to optimize its capture efficiency. This will be applied to the ECR-based Charge Breeding technique, that will improve the performances of the SPES ISOL-facility at Laboratori Nazionali di Legnaro-INFN. Finally, PANDORA will be suitable for energy conversion, making the plasma a source of high-intensity electromagnetic radiation, for applications in material science and archaeometry.

Recent results of the Filippov-type PF experiments at Kurchatov Institute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krauz, V. I.; Karakin, M. A.; Khautiev, E. Yu.

2006-01-15

The experiments with various plasma-producing substances performed recently were the main content at the PF-3 facility studies: (i) The dependence of the wire array compression on the number of wires was investigated with the deuterium as a filling gas. (ii) The neutron output, 5{center_dot}106 neutrons per shot, was registered in experiments with deuterium-polythene fibers when argon was used as a filling gas. Experimental confirmation of fibers pre-heating by radiation of the current sheath compressed to an axis was obtained. (iii) Studies of interaction of dense high-temperature plasma with the condensed disperse substance (dust) were continued. The dependence of the pinchmore » dynamics on the dust target parameters was investigated. In the shots with dust fraction of the fine-disperse Al2O3 powder, modes with increased pinch MHD-stability are found.« less

Laser-optical measurements of the velocities of the plasma jets formed from different gases in a kilojoule-range plasma focus facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polukhin, S. N., E-mail: snpol@lebedev.ru; Dzhamankulov, A. M.; Gurei, A. E.

The velocities of the plasma jets formed from Ne, N{sub 2}, Ar, and Xe gases in plasma focus facilities were determined by means of laser-optical shadowgraphy of the shock waves generated at the jet leading edge. In spite of the almost tenfold ratio between the atomic weights of these gases, the outflow velocities of the plasma jets formed in experiments with these gases differ by less than twice, in the range of (0.7–1.1) × 10{sup 7} cm/s under similar discharge conditions. The energies of the jet ions were found to vary from 0.7 keV for nitrogen to 4 keV formore » xenon.« less

Modeling Hohlraum-Based Laser Plasma Instability Experiments

NASA Astrophysics Data System (ADS)

Meezan, N. B.

2005-10-01

Laser fusion targets must control laser-plasma instabilities (LPI) in order to perform as designed. We present analyses of recent hohlraum LPI experiments from the Omega laser facility. The targets, gold hohlraums filled with gas or SiO2 foam, are preheated by several 3φ beams before an interaction beam (2φ or 3φ) is fired along the hohlraum axis. The experiments are simulated in 2-D and 3-D using the code hydra. The choice of electron thermal conduction model in hydra strongly affects the simulated plasma conditions. This work is part of a larger effort to systematically explore the usefulness of linear gain as a design tool for fusion targets. We find that the measured Raman and Brillouin backscatter scale monotonically with the peak linear gain calculated for the target; however, linear gain is not sufficient to explain all trends in the data. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48.

Planned Experiments on the Princeton Advanced Test Stand

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2010-11-01

The Princeton Advanced Test Stand (PATS) device is an experimental facility based on the STS-100 high voltage test stand transferred from LBNL. It consists of a multicusp RF ion source, a pulsed extraction system capable of forming high-perveance 100keV ion beams, and a large six-foot-long vacuum with convenient access for beam diagnostics. This results in a flexible system for studying high perveance ion beams relevant to NDCX-I/II, including experiments on beam neutralization by ferroelectric plasma sources (FEPS) being developed at PPPL. Research on PATS will concern the basic physics of beam-plasma interactions, such as the effects of volume neutralization on beam emittance, as well as optimizing technology of the FEPS. PATS combines the advantage of an ion beam source and a large-volume plasma source in a chamber with ample access for diagnostics, resulting in a robust setup for investigating and improving relevant aspects of neutralized drift. There are also plans for running the ion source with strongly electro-negative gases such as chlorine, making it possible to extract positive or negative ion beams.

Laser plasma interaction in rugby-shaped hohlraums

NASA Astrophysics Data System (ADS)

Masson-Laborde, P.-E.; Philippe, F.; Tassin, V.; Monteil, M.-C.; Gauthier, P.; Casner, A.; Depierreux, S.; Seytor, P.; Teychenne, D.; Loiseau, P.; Freymerie, P.

2014-10-01

Rugby shaped-hohlraum has proven to give high performance compared to a classical similar-diameter cylinder hohlraum. Due to this performance, this hohlraum has been chosen as baseline ignition target for the Laser MegaJoule (LMJ). Many experiments have therefore been performed during the last years on the Omega laser facility in order to study in details the rugby hohlraum. In this talk, we will discuss the interpretation of these experiments from the point of view of the laser plasma instability problem. Experimental comparisons have been done between rugby, cylinder and elliptical shape rugby hohlraums and we will discuss how the geometry differences will affect the evolution of laser plasma instabilities (LPI). The efficiency of laser smoothing techniques on these instabilities will also be discussed as well as gas filling effect. The experimental results will be compared with FCI2 hydroradiative calculations and linear postprocessing with Piranah. Experimental Raman and Brillouin spectrum, from which we can infer the location of the parametric instabilities, will be compared to simulated ones, and will give the possibility to compare LPI between the different hohlraum geometries.

The Influence of Process Equipment on the Properties of Suspension Plasma Sprayed Yttria-Stabilized Zirconia Coatings

NASA Astrophysics Data System (ADS)

Marr, Michael; Waldbillig, David; Kesler, Olivera

2013-03-01

Suspension plasma-sprayed YSZ coatings were deposited at lab-scale and production-type facilities to investigate the effect of process equipment on coating properties. The target application for these coatings is solid oxide fuel cell (SOFC) electrolytes; hence, dense microstructures with low permeability values were preferred. Both facilities had the same torch but different suspension feeding systems, torch robots, and substrate holders. The lab-scale facility had higher torch-substrate relative speeds compared with the production-type facility. On porous stainless steel substrates, permeabilities and microstructures were comparable for coatings from both facilities, and no segmentation cracks were observed. Coating permeability was further reduced by increasing substrate temperatures during deposition or reducing suspension feed rates. On SOFC cathode substrates, coatings made in the production-type facility had higher permeabilities and more segmentation cracks compared with coatings made in the lab-scale facility. Increased cracking in coatings from the production-type facility was likely caused mainly by its lower torch-substrate relative speed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. Ono, M. Jaworski, R. Kaita, C. N. Skinner, J.P. Allain, R. Maingi, F. Scotti, V.A. Soukhanovskii, and the NSTX-U Team

Developing a reactor compatible divertor and managing the associated plasma material interaction (PMI) has been identified as a high priority research area for magnetic confinement fusion. Accordingly on NSTXU, the PMI research has received a strong emphasis. With ~ 15 MW of auxiliary heating power, NSTX-U will be able to test the PMI physics with the peak divertor plasma facing component (PFC) heat loads of up to 40-60 MW/m2 . To support the PMI research, a comprehensive set of PMI diagnostic tools are being implemented. The snow-flake configuration can produce exceptionally high divertor flux expansion of up to ~ 50.more » Combined with the radiative divertor concept, the snow-flake configuration has reduced the divertor heat flux by an order of magnitude in NSTX. Another area of active PMI investigation is the effect of divertor lithium coating (both in solid and liquid phases). The overall NSTX lithium PFC coating results suggest exciting opportunities for future magnetic confinement research including significant electron energy confinement improvements, Hmode power threshold reduction, the control of Edge Localized Modes (ELMs), and high heat flux handling. To support the NSTX-U/PPPL PMI research, there are also a number of associated PMI facilities implemented at PPPL/Princeton University including the Liquid Lithium R&D facility, Lithium Tokamak Experiment, and Laboratories for Materials Characterization and Surface Chemistry.« less

Stable dense plasma jets produced at laser power densities around 10{sup 14} W/cm{sup 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.

2006-06-15

The results of investigations are presented that are connected with defocused laser beam-planar target interaction. Following the very large focus laser-plasma interaction experiments on the Nova [H. T. Powell, J. A. Caird, J. E. Murray, and C. E. Thompson, 1991 ICF Annual Report UCRL-LR-105820-91, p. 163 (1991)] and GEKKO-XII [C. Yamanaka, Y. Kato, Y. Izawa, K. Yoshida, T. Yamanaka, T. Sasaki, T. Nakatsuka, J. Kuroda, and S. Nakai, IEEE J. Quantum Electron. QE-17, 1639 (1981)] lasers, as well as on the National Ignition Facility (NIF) laser [W. J. Hogan, E. I. Moses, B. E. Warner, M. S. Sorem, and J.more » M. Soures, Nucl. Fusion 41, 567 (2001)] with generation of high Mach number jets, this paper is devoted to similar jet generation with very detailed measurements of density profiles by using high-power lasers at large focus conditions. The experiment was carried out with target materials of different mass densities (Al, Cu, Ag, Ta, and Pb) using the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikowa, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. The investigations were conducted for the laser radiation energy of 100 J at two wavelengths of 1.315 and 0.438 {mu}m (the first and third harmonics of laser radiation), pulse duration of 0.4 ns, and a focal spot radius of 300 {mu}m. Most of the experimental data were obtained by means of a three-frame laser interferometer and an x-ray streak camera; the crater parameters were obtained by using the crater replica technique. These investigations have shown that stable dense plasma jets can be produced in a simple configuration of laser beam-planar target interaction, provided that a proper target material is used.« less

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

NASA Astrophysics Data System (ADS)

Cerjan, Ch J.; Bernstein, L.; Berzak Hopkins, L.; Bionta, R. M.; Bleuel, D. L.; Caggiano, J. A.; Cassata, W. S.; Brune, C. R.; Frenje, J.; Gatu-Johnson, M.; Gharibyan, N.; Grim, G.; Hagmann, Chr; Hamza, A.; Hatarik, R.; Hartouni, E. P.; Henry, E. A.; Herrmann, H.; Izumi, N.; Kalantar, D. H.; Khater, H. Y.; Kim, Y.; Kritcher, A.; Litvinov, Yu A.; Merrill, F.; Moody, K.; Neumayer, P.; Ratkiewicz, A.; Rinderknecht, H. G.; Sayre, D.; Shaughnessy, D.; Spears, B.; Stoeffl, W.; Tommasini, R.; Yeamans, Ch; Velsko, C.; Wiescher, M.; Couder, M.; Zylstra, A.; Schneider, D.

2018-03-01

The generation of dynamic high energy density plasmas in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capture cross-section evaluation, fission fragment production, and ion energy loss measurement in electron-degenerate plasmas. More generally, the NIF conditions provide a singular environment to investigate the interplay of atomic and nuclear processes such as plasma screening effects upon thermonuclear reactivity. Achieving enhanced understanding of many of these effects will also significantly advance fusion energy research and challenge existing theoretical models.

Estimations of Mo X-pinch plasma parameters on QiangGuang-1 facility by L-shell spectral analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Jian; Qiu, Aici; State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024

2013-08-15

Plasma parameters of molybdenum (Mo) X-pinches on the 1-MA QiangGuang-1 facility were estimated by L-shell spectral analysis. X-ray radiation from X-pinches had a pulsed width of 1 ns, and its spectra in 2–3 keV were measured with a time-integrated X-ray spectrometer. Relative intensities of spectral features were derived by correcting for the spectral sensitivity of the spectrometer. With an open source, atomic code FAC (flexible atomic code), ion structures, and various atomic radiative-collisional rates for O-, F-, Ne-, Na-, Mg-, and Al-like ionization stages were calculated, and synthetic spectra were constructed at given plasma parameters. By fitting the measured spectramore » with the modeled, Mo X-pinch plasmas on the QiangGuang-1 facility had an electron density of about 10{sup 21} cm{sup −3} and the electron temperature of about 1.2 keV.« less

Simulations of Laboratory Astrophysics Experiments using the CRASH code

NASA Astrophysics Data System (ADS)

Trantham, Matthew; Kuranz, Carolyn; Manuel, Mario; Keiter, Paul; Drake, R. P.

2014-10-01

Computer simulations can assist in the design and analysis of laboratory astrophysics experiments. The Center for Radiative Shock Hydrodynamics (CRASH) at the University of Michigan developed a code that has been used to design and analyze high-energy-density experiments on OMEGA, NIF, and other large laser facilities. This Eulerian code uses block-adaptive mesh refinement (AMR) with implicit multigroup radiation transport, electron heat conduction and laser ray tracing. This poster/talk will demonstrate some of the experiments the CRASH code has helped design or analyze including: Kelvin-Helmholtz, Rayleigh-Taylor, imploding bubbles, and interacting jet experiments. This work is funded by the Predictive Sciences Academic Alliances Program in NNSA-ASC via Grant DEFC52-08NA28616, by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, Grant Number DE-NA0001840, and by the National Laser User Facility Program, Grant Number DE-NA0000850.

Evolution of Gas Cell Targets for Magnetized Liner Inertial Fusion Experiments at the Sandia National Laboratories PECOS Test Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paguio, R. R.; Smith, G. E.; Taylor, J. L.

Z-Beamlet (ZBL) experiments conducted at the PECOS test facility at Sandia National Laboratories (SNL) investigated the nonlinear processes in laser plasma interaction (or laserplasma instabilities LPI) that complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray that can occur in large-scale laser-heated gas cell targets. These targets and experiments were designed to provide better insight into the physics of the laser preheat stage of the Magnetized Liner Inertial Fusion (MagLIF) scheme being tested on the SNL Z-machine. The experiments aim to understand the tradeoffs between laser spot size, laser pulse shape, laser entrance hole (LEH) windowmore » thickness, and fuel density for laser preheat. Gas cell target design evolution and fabrication adaptations to accommodate the evolving experiment and scientific requirements are also described in this paper.« less

Evolution of Gas Cell Targets for Magnetized Liner Inertial Fusion Experiments at the Sandia National Laboratories PECOS Test Facility

DOE PAGES

Paguio, R. R.; Smith, G. E.; Taylor, J. L.; ...

2017-12-04

Z-Beamlet (ZBL) experiments conducted at the PECOS test facility at Sandia National Laboratories (SNL) investigated the nonlinear processes in laser plasma interaction (or laserplasma instabilities LPI) that complicate the deposition of laser energy by enhanced absorption, backscatter, filamentation and beam-spray that can occur in large-scale laser-heated gas cell targets. These targets and experiments were designed to provide better insight into the physics of the laser preheat stage of the Magnetized Liner Inertial Fusion (MagLIF) scheme being tested on the SNL Z-machine. The experiments aim to understand the tradeoffs between laser spot size, laser pulse shape, laser entrance hole (LEH) windowmore » thickness, and fuel density for laser preheat. Gas cell target design evolution and fabrication adaptations to accommodate the evolving experiment and scientific requirements are also described in this paper.« less

Complex Plasmas under free fall conditions aboard the International Space Station

NASA Astrophysics Data System (ADS)

Konopka, Uwe; Thomas, Edward, Jr.; Funk, Dylan; Doyle, Brandon; Williams, Jeremiah; Knapek, Christina; Thomas, Hubertus

2017-10-01

Complex Plasmas are dynamically dominated by massive, highly negatively charged, micron-sized particles. They are usually strongly coupled and as a result can show fluid-like behavior or undergo phase transitions to form crystalline structures. The dynamical time scale of these systems is easily accessible in experiments because of the relatively high mass/inertia of the particles. However, the high mass also leads to sedimentation effects and as a result prevents the conduction of large scale, fully three dimensional experiments that are necessary to utilize complex plasmas as model systems in the transition to continuous media. To reduce sedimentation influences it becomes necessary to perform experiments in a free-fall (``microgravity'') environment, such as the ISS based experiment facility ``Plasma-Kristall-4'' (``PK-4''). In our paper we will present our recently started research activities to investigate the basic properties of complex plasmas by utilizing the PK-4 experiment facility aboard the ISS. We further give an overview of developments towards the next generation experiment facility ``Ekoplasma'' (formerly named ``PlasmaLab'') and discuss potential additional small-scale space-based experiment scenarios. This work was supported by the JPL/NASA (JPL-RSA 1571699), the US Dept. of Energy (DE-SC0016330) and the NSF (PHY-1613087).

Perspectives on High-Energy-Density Physics

NASA Astrophysics Data System (ADS)

Drake, R. Paul

2008-11-01

Much of 21st century plasma physics will involve work to produce, understand, control, and exploit very non-traditional plasmas. High-energy density (HED) plasmas are often examples, variously involving strong Coulomb interactions and few particles per Debeye sphere, dominant radiation effects, strongly relativistic effects, or strongly quantum-mechanical behavior. Indeed, these and other modern plasma systems often fall outside the early standard theoretical definitions of ``plasma''. This presentation will focus on two types of HED plasmas that exhibit non-traditional behavior. Our first example will be the plasmas produced by extremely strong shock waves. Shock waves are present across the entire realm of plasma densities, often in space or astrophysical contexts. HED shock waves (at pressures > 1 Mbar) enable studies in many areas, from equations of state to hydrodynamics to radiation hydrodynamics. We will specifically consider strongly radiative shocks, in which the radiative energy fluxes are comparable to the mechanical energy fluxes that drive the shocks. Modern HED facilities can produce such shocks, which are also present in dense, energetic, astrophysical systems such as supernovae. These shocks are also excellent targets for advanced simulations due to their range of spatial scales and complex radiation transport. Our second example will be relativistic plasmas. In general, these vary from plasmas containing relativistic particle beams, produced for some decades in the laboratory, to the relativistic thermal plasmas present for example in pulsar winds. Laboratory HED relativistic plasmas to date have been those produced by laser beams of irradiance ˜ 10^18 to 10^22 W/cm^2 or by accelerator-produced HED electron beams. These have applications ranging from generation of intense x-rays to production of proton beams for radiation therapy to acceleration of electrons. Here we will focus on electron acceleration, a spectacular recent success and a rare example in which simplicity emerges from the complexity present in the plasma state.

Emission Spectroscopy and Radiometric Measurements in the NASA Ames IHF Arc Jet Facility

NASA Technical Reports Server (NTRS)

Winter, Michael W.; Raiche, George A.; Prabhu, Dinesh K.

2012-01-01

Plasma diagnostic measurement campaigns in the NASA Ames Interaction Heating Facility (IHF) have been conducted over the last several years with a view towards characterizing the flow in the arc jet facility by providing data necessary for modeling and simulation. Optical emission spectroscopy has been used in the plenum and in the free jet of the nozzle. Radiation incident over a probe surface has also been measured using radiometry. Plenum measurements have shown distinct radial profiles of temperature over a range of operating conditions. For cases where large amounts of cold air are added radially to the main arc-heated stream, the temperature profiles are higher by as much as 1500 K than the profiles assumed in flow simulations. Optical measurements perpendicular to the flow direction in the free jet showed significant contributions to the molecule emission through inverse pre-dissociation, thus allowing determination of atom number densities from molecular emission. This has been preliminarily demonstrated with the N2 1st Positive System. Despite the use of older rate coefficients, the resulting atom densities are reasonable and surprisingly close to flow predictions.

Novel test-bed facility for PSI issues in fusion reactor conditions on the base of next generation QSPA plasma accelerator

NASA Astrophysics Data System (ADS)

Garkusha, I. E.; Chebotarev, V. V.; Herashchenko, S. S.; Makhlaj, V. A.; Kulik, N. V.; Ladygina, M. S.; Marchenko, A. K.; Petrov, Yu. V.; Staltsov, V. V.; Shevchuk, P. V.; Solyakov, D. G.; Yelisyeyev, D. V.

2017-11-01

In this report a concept of a new generation QSPA with external B-field up to 2 T has been discussed. A novel test-bed facility, which was recently constructed in Kharkov IPP NSC KIPT, has been described. It allows for a new level of plasma stream parameters and its wide variation in new QSPA-M device, as well as possible combination of steady-state and pulsed plasma loads to the materials during the exposures. First plasma is recently obtained. Careful optimization of the operational regimes of the plasma accelerator’s functional components and plasma dynamics in the magnetic system of QSPA-M device has started approaching step by step the necessary level of plasma parameters and their effective variation. The relevant results on plasma stream characterization are presented. Energy density distributions in plasma stream have been measured with calorimetry. Spectroscopy and probe technique have also been applied for plasma parameters measurements. The obtained results demonstrate the ability of QSPA-M to reproduce the ELM impacts in fusion reactor, both in terms of heat load and particle flux to the surface.

Plasma MRI Experiments at UW-Madison

NASA Astrophysics Data System (ADS)

Flanagan, K.; Clark, M.; Desangles, V.; Siller, R.; Wallace, J.; Weisberg, D.; Forest, C. B.

2015-11-01

Experiments for driving Keplerian-like flow profiles on both the Plasma Couette Experiment Upgrade (PCX-U) and the Wisconsin Plasma Astrophysics Laboratory (WiPAL) user facility are described. Instead of driving flow at the boundaries, as is typical in many liquid metal Couette experiments, a global drive is implemented. A large radial current is drawn across a small axial field generating torque across the whole profile. This global electrically driven flow is capable of producing profiles similar to Keplerian flow. PCX-U has been purposely constructed for MRI experiments, while similar experiments on the WiPAL device show the versatility of the user facility and provide a larger plasma volume. Numerical calculations show the predicted parameter spaces for exciting the MRI in these plasmas and the equilibrium flow profiles expected. In both devices, relevant MRI parameters appear to be within reach of typical operating characteristics.

Narrow Energy Spread Protons and Ions from High-Intensity, High-Contrast Laser Solid Target Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dollar, Franklin; Matsuoka, Takeshi; McGuffey, Christopher

2010-11-04

Recent simulations show that an idealized, high intensity, short pulse laser can generate quasi-monoenergetic proton beams with energies over 100 MeV in an interaction with a thin film. However, most short pulse laser facilities with sufficient intensity have difficulty controlling the nanosecond and picosecond contrast necessary to realize such a regime. Experiments were performed to investigate proton and ion acceleration from a high contrast, short pulse laser by employing dual plasma mirrors along with a deformable mirror at the HERCULES laser facility at the Center for Ultrafast Optical Sciences, University of Michigan. Plasma mirrors were characterized, allowing a 50% throughputmore » with an intensity contrast increase of 105. The focal spot quality was also exceptional, showing a 1.1 micron full width at half maximum (FWHM) focal diameter. Experiments were done using temporally cleaned 30 TW, 32 fs pulses to achieve an intensity of up to 10{sup 21} Wcm{sup -2} on Si{sub 3}N{sub 4} and Mylar targets with thicknesses ranging 50 nm to 13 microns. Proton beams with energy spreads below 2 MeV were observed from all thicknesses, peaking with energies up to 10.3 MeV and an energy spread of 0.8 MeV. Similar narrow energy spreads were observed for oxygen, nitrogen, and carbon at the silicon nitride thickness of 50 nm with energies up to 24 MeV with an energy spread of 3 MeV, whereas the energy spread is greatly increased at a larger thickness. Maximum energies were confirmed with CR39 track detectors, while a Thomson ion spectrometer was used to gauge the monoenergetic nature of the beam.« less

Studies of Plasma Instabilities Excited by Ground-Based High Power HF (Heating) Facilities and of X and Gamma Ray Emission in Runaway Breakdown Processes

DTIC Science & Technology

2006-08-01

latitude ( HAARP , TROMSO) and mid latitude (SURA) facilities [1]. The very strong and fully reproducible plasma perturbations in ionosphere are observed...beam propagating along magnetic field (θ = 0), in this case factor κs ≈ 1. As an a example we will consider now the HAARP facility. The ERP for HAARP ...as a function of fre- quency f0 is presented in the Table 1. ISTC 2236p 12 Table 1 ERP as function of wave frequency for HAARP (2001) f0 (MHz

Developing the science and technology for the Material Plasma Exposure eXperiment

NASA Astrophysics Data System (ADS)

Rapp, J.; Biewer, T. M.; Bigelow, T. S.; Caneses, J. F.; Caughman, J. B. O.; Diem, S. J.; Goulding, R. H.; Isler, R. C.; Lumsdaine, A.; Beers, C. J.; Bjorholm, T.; Bradley, C.; Canik, J. M.; Donovan, D.; Duckworth, R. C.; Ellis, R. J.; Graves, V.; Giuliano, D.; Green, D. L.; Hillis, D. L.; Howard, R. H.; Kafle, N.; Katoh, Y.; Lasa, A.; Lessard, T.; Martin, E. H.; Meitner, S. J.; Luo, G.-N.; McGinnis, W. D.; Owen, L. W.; Ray, H. B.; Shaw, G. C.; Showers, M.; Varma, V.; the MPEX Team

2017-11-01

Linear plasma generators are cost effective facilities to simulate divertor plasma conditions of present and future fusion reactors. They are used to address important R&D gaps in the science of plasma material interactions and towards viable plasma facing components for fusion reactors. Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The steady-state linear plasma device MPEX will address this regime with electron temperatures of 1-10 eV and electron densities of 1021{\\text{}}-1020 m-3 . The resulting heat fluxes are about 10 MW m-2 . MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with electron Bernstein wave (EBW) heating and ion cyclotron resonance heating with a total installed power of 800 kW. The linear device Proto-MPEX, forerunner of MPEX consisting of 12 water-cooled copper coils, has been operational since May 2014. Its helicon antenna (100 kW, 13.56 MHz) and EC heating systems (200 kW, 28 GHz) have been commissioned and 14 MW m-2 was delivered on target. Furthermore, electron temperatures of about 20 eV have been achieved in combined helicon and ECH heating schemes at low electron densities. Overdense heating with EBW was achieved at low heating powers. The operational space of the density production by the helicon antenna was pushed up to 1.1 × 1020 m-3 at high magnetic fields of 1.0 T at the target. The experimental results from Proto-MPEX will be used for code validation to enable predictions of the source and heating performance for MPEX. MPEX, in its last phase, will be capable to expose neutron-irradiated samples. In this concept, targets will be irradiated in ORNL’s High Flux Isotope Reactor and then subsequently exposed to fusion reactor relevant plasmas in MPEX.

Prediction of In-Space Durability of Protected Polymers Based on Ground Laboratory Thermal Energy Atomic Oxygen

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon; DiFilippo, Frank J.

1996-01-01

The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.

Plasma-based Compressor Stall Control

NASA Astrophysics Data System (ADS)

McGowan, Ryan; Corke, Thomas

2017-11-01

The use of dielectric barrier discharge (DBD) plasma actuator casing treatment to prevent or delay stall inception in an axial fan is examined. The actuators are powered by a pulsed-DC waveform which induces a larger peak velocity than a purely AC waveform such as a sine or sawtooth wave. With this system, a high-voltage DC source is supplied to both electrodes, remaining constant in time for the exposed electrode. Meanwhile, the covered electrode is periodically grounded for several microseconds and allowed to rise back to the source DC level. To test the actuators' ability to interact with and modify the formation of stall cells, a facility has been designed and constructed around nonconductive fan blades. The actuators are installed in the fan casing near the blade tips. The instrumentation allows for the measurement of rotating pressure disturbances (traveling stall cells) in this tip gap region as well as fan performance characteristics including pressure rise and flow rate. The casing plasma actuation is found to reduce the correlation of the rotating stall cells, thereby extending the stall margin of the fan. Various azimuthal arrangements of the plasma actuator casing treatment is explored, as well as input voltage levels to the actuator to determine optimum conditions. NASA SBIR Contract NNX14CC12C.

DIII-D Upgrade to Prepare the Basis for Steady-State Burning Plasmas

NASA Astrophysics Data System (ADS)

Buttery, R. J.; Guo, H. Y.; Taylor, T. S.; Wade, M. R.; Hill, D. N.

2014-10-01

Future steady-state burning plasma facilities will access new physics regimes and modes of plasma behavior. It is vital to prepare for this both experimentally using existing facilities, and theoretically in order to develop the tools to project to and optimize these devices. An upgrade to DIII-D is proposed to address the three critical aspects where research must go beyond what we can do now: (i) torque free electron heating to address the energy, particle and momentum transport mechanisms of burning plasmas using electron cyclotron (EC) heating and full power balanced neutral beams; (ii) off-axis heating and current drive to develop the path to true fusion steady state by reorienting neutral beams and deploying EC and helicon current drive; (iii) a new divertor with hot walls and reactor relevant materials to develop the basis for benign detached divertor operation compatible with wall materials and a high performance fusion core. These elements with modest incremental cost and enacted as a user facility for the whole US program will enable the US to lead on ITER and take a decision to proceed with a Fusion Nuclear Science Facility. Work supported by the US Department of Energy under DE-FC02-04ER54698 and DE-AC52-07NA27344.

Advanced Accelerators: Particle, Photon and Plasma Wave Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Ronald L.

2017-06-29

The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to studymore » techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.« less

A final report to the Laboratory Directed Research and Development committee on Project 93-ERP-075: ``X-ray laser propagation and coherence: Diagnosing fast-evolving, high-density laser plasmas using X-ray lasers``

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wan, A.S.; Cauble, R.; Da Silva, L.B.

1996-02-01

This report summarizes the major accomplishments of this three-year Laboratory Directed Research and Development (LDRD) Exploratory Research Project (ERP) entitled ``X-ray Laser Propagation and Coherence: Diagnosing Fast-evolving, High-density Laser Plasmas Using X-ray Lasers,`` tracking code 93-ERP-075. The most significant accomplishment of this project is the demonstration of a new laser plasma diagnostic: a soft x-ray Mach-Zehnder interferometer using a neonlike yttrium x-ray laser at 155 {angstrom} as the probe source. Detailed comparisons of absolute two-dimensional electron density profiles obtained from soft x-ray laser interferograms and profiles obtained from radiation hydrodynamics codes, such as LASNEX, will allow us to validate andmore » benchmark complex numerical models used to study the physics of laser-plasma interactions. Thus the development of soft x-ray interferometry technique provides a mechanism to probe the deficiencies of the numerical models and is an important tool for, the high-energy density physics and science-based stockpile stewardship programs. The authors have used the soft x-ray interferometer to study a number of high-density, fast evolving, laser-produced plasmas, such as the dynamics of exploding foils and colliding plasmas. They are pursuing the application of the soft x-ray interferometer to study ICF-relevant plasmas, such as capsules and hohlraums, on the Nova 10-beam facility. They have also studied the development of enhanced-coherence, shorter-pulse-duration, and high-brightness x-ray lasers. The utilization of improved x-ray laser sources can ultimately enable them to obtain three-dimensional holographic images of laser-produced plasmas.« less

UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

NASA Astrophysics Data System (ADS)

Watkins, Brenton; Fallen, Christopher; Secan, James

Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF frequency increasing near the gyro-harmonic value were conducted. The FM scan rate was sufficiently slow that the electron density was approximately in an equilibrium state. For these experiments the altitude of the HF interaction follows a near straight line downward parallel to the altitude-dependent gyro-harmonic level.

Electron temperature diagnostics of aluminium plasma in a z-pinch experiment at the “QiangGuang-1" facility

NASA Astrophysics Data System (ADS)

Li, Mo; Wu, Jian; Wang, Liang-Ping; Wu, Gang; Han, Juan-Juan; Guo, Ning; Qiu, Meng-Tong

2012-12-01

Two curved crystal spectrometers are set up on the “QiangGuang-1" generator to measure the z-pinch plasma spectra emitted from planar aluminum wire array loads. Kodak Biomax-MS film and an IRD AXUVHS5# array are employed to record time-integrated and time-resolved free-bound radiation, respectively. The photon energy recorded by each detector is ascertained by using the L-shell lines of molybdenum plasma. Based on the exponential relation between the continuum power and photon energies, the aluminum plasma electron temperatures are measured. For the time-integrated diagnosis, several “bright spots" indicate electron temperatures between (450 eV ~ 520 eV) ± 35%. And for the time-resolved ones, the result shows that the electron temperature reaches about 800 eV ± 30% at peak power. The system satisfies the demand of z-pinch plasma electron temperature diagnosis on a ~ 1 MA facility.

Plasma Pancakes and Deep Cavities Generated by High Power Radio Waves from the Arecibo Observatory

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Briczinski, S. J., Jr.; Zawdie, K.; Huba, J.; Siefring, C. L.; Sulzer, M. P.; Nossa, E.; Aponte, N.; Perillat, P.; Jackson-Booth, N.

2017-12-01

Breakdown of the neutral atmosphere at ionospheric altitudes can be achieved with high power HF waves that reflect on the bottomside of the ionosphere. For overdense heating (i.e., wave frequency < maximum plasma frequency in the F-layer), the largest electric fields in the plasma are found just below the reflection altitude. There, electromagnetic waves are converted into electron plasma (Langmir) waves and ion acoustic waves. These waves are measured by scattering of the 430 MHz radar at Arecibo to from an enhanced plasma line. The photo-electron excitation of Langmuir waves yields a weaker plasma-line profile that shows the complete electron profile with the radar. Once HF enhanced Langmuir waves are formed, they can accelerate the photo-electron population to sufficient energies for neutral breakdown and enhanced ionization inside the HF Radio Beam. Plasma pancakes are produced because the breakdown process continues to build up plasma on bottom of the breakdown clouds and recombination occurs on the older breakdown plasma at the top of these clouds. Thus, the plasma pancake falls with altitude from the initial HF wave reflection altitude near 250 km to about 160 km where ion-electron recombination prevents the plasma cloud from being sustained by the high power HF. Experiments in March 2017 have produced plasma pancakes with about 100 Mega-Watts effective radiated power 5.1 MHz with the Arecibo HF Facility. Observations using the 430 MHz radar show falling plasma pancakes that disappear at low altitudes and reform at the F-layer critical reflection altitude. Sometimes the periodic and regular falling motion of the plasma pancakes is influenced by Acoustic Gravity Waves (AGW) propagating through the modified HF region. A rising AGW can cause the plasma pancake to reside at nearly constant altitude for 10 to 20 minutes. Dense cavities are also produced by high power radio waves interacting with the F-Layer. These structures are observed with the Arecibo 430 MHz radar as intense bight-outs in the plasma profile. Multiple cavities are seen simultaneously.

Acceleration of plasma electrons by intense nonrelativistic ion and electron beams propagating in background plasma due to two-stream instability

NASA Astrophysics Data System (ADS)

Kaganovich, Igor D.

2015-11-01

In this paper we study the effects of the two-stream instability on the propagation of intense nonrelativistic ion and electron beams in background plasma. Development of the two-stream instability between the beam ions and plasma electrons leads to beam breakup, a slowing down of the beam particles, acceleration of the plasma particles, and transfer of the beam energy to the plasma particles and wave excitations. Making use of the particle-in-cell codes EDIPIC and LSP, and analytic theory we have simulated the effects of the two-stream instability on beam propagation over a wide range of beam and plasma parameters. Because of the two-stream instability the plasma electrons can be accelerated to velocities as high as twice the beam velocity. The resulting return current of the accelerated electrons may completely change the structure of the beam self - magnetic field, thereby changing its effect on the beam from focusing to defocusing. Therefore, previous theories of beam self-electromagnetic fields that did not take into account the effects of the two-stream instability must be significantly modified. This effect can be observed on the National Drift Compression Experiment-II (NDCX-II) facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma. Particle-in-cell, fluid simulations, and analytical theory also reveal the rich complexity of beam- plasma interaction phenomena: intermittency and multiple regimes of the two-stream instability in dc discharges; band structure of the growth rate of the two-stream instability of an electron beam propagating in a bounded plasma and repeated acceleration of electrons in a finite system. In collaboration with E. Tokluoglu, D. Sydorenko, E. A. Startsev, J. Carlsson, and R. C. Davidson. Research supported by the U.S. Department of Energy.

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

DOE PAGES

Cerjan, Ch J.; Bernstein, L.; Hopkins, L. Berzak; ...

2017-08-16

We present the generation of dynamic high energy density plasmas in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capturemore » cross-section evaluation, fission fragment production, and ion energy loss measurement in electron-degenerate plasmas. More generally, the NIF conditions provide a singular environment to investigate the interplay of atomic and nuclear processes such as plasma screening effects upon thermonuclear reactivity. Lastly, achieving enhanced understanding of many of these effects will also significantly advance fusion energy research and challenge existing theoretical models.« less

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cerjan, Ch J.; Bernstein, L.; Hopkins, L. Berzak

We present the generation of dynamic high energy density plasmas in the pico- to nano-second time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capturemore » cross-section evaluation, fission fragment production, and ion energy loss measurement in electron-degenerate plasmas. More generally, the NIF conditions provide a singular environment to investigate the interplay of atomic and nuclear processes such as plasma screening effects upon thermonuclear reactivity. Lastly, achieving enhanced understanding of many of these effects will also significantly advance fusion energy research and challenge existing theoretical models.« less

Advances in simulation of wave interactions with extended MHD phenomena

NASA Astrophysics Data System (ADS)

Batchelor, D.; Abla, G.; D'Azevedo, E.; Bateman, G.; Bernholdt, D. E.; Berry, L.; Bonoli, P.; Bramley, R.; Breslau, J.; Chance, M.; Chen, J.; Choi, M.; Elwasif, W.; Foley, S.; Fu, G.; Harvey, R.; Jaeger, E.; Jardin, S.; Jenkins, T.; Keyes, D.; Klasky, S.; Kruger, S.; Ku, L.; Lynch, V.; McCune, D.; Ramos, J.; Schissel, D.; Schnack, D.; Wright, J.

2009-07-01

The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: 1) recent improvements to the IPS, 2) application of the IPS for very high resolution simulations of ITER scenarios, 3) studies of resistive and ideal MHD stability in tokamk discharges using IPS facilities, and 4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

Interaction of a solar array with an ion thruster due to the charge-exchange plasma

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1976-01-01

The generation of a charge exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma is described accurately from thruster geometry and operating conditions. The transport of the charge exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

A tandem mirror hybrid plume plasma propulsion facility

NASA Technical Reports Server (NTRS)

Chang-Diaz, F. R.; Yang, T. F.; Krueger, W. A.; Peng, S.; Urbahn, J.; Yao, X.; Griffin, D.

1988-01-01

A concept in electrodeless plasma propulsion, which is also capable of delivering a variable Isp, is presented. The concept involves a three-stage system of plasma injection, heating, and subsequent ejection through a magnetic nozzle. The nozzle produces the hybrid plume by the coaxial injection of hypersonic neutral gas. The gas layer, thus formed, protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The physics of this concept is evaluated numerically through full spatial and temporal simulations; these explore the operating characteristics of such a device over a wide region of parameter space. An experimental facility to study the plasma dynamics in the hybrid plume was built. The device consists of a tandem mirror operating in an asymmetric mode. A later upgrade of this system will incorporate a cold plasma injector at one end of the machine. Initial experiments involve the full characterization of the operating envelope, as well as extensive measurements of plasma properties at the exhaust. The results of the numerical simulations are described.

The national ignition facility and atomic data

NASA Astrophysics Data System (ADS)

Crandall, David H.

1998-07-01

The National Ignition Facility (NIF) is under construction, capping over 25 years of development of the inertial confinement fusion concept by providing the facility to obtain fusion ignition in the laboratory for the first time. The NIF is a 192 beam glass laser to provide energy controlled in space and time so that a millimeter-scale capsule containing deuterium and tritium can be compressed to fusion conditions. Light transport, conversion of light in frequency, interaction of light with matter in solid and plasma forms, and diagnostics of extreme material conditions on small scale all use atomic data in preparing for use of the NIF. The NIF will provide opportunity to make measurements of atomic data in extreme physical environments related to fusion energy, nuclear weapon detonation, and astrophysics. The first laser beams of NIF should be operational in 2001 and the full facility completed at the end of 2003. NIF is to provide 1.8 megajoule of blue light on fusion targets and is intended to achieve fusion ignition by about the end of 2007. Today's inertial fusion development activities use atomic data to design and predict fusion capsule performance and in non-fusion applications to analyze radiation transport and radiation effects on matter. Conditions investigated involve radiation temperature of hundreds of eV, pressures up to gigabars and time scales of femptoseconds.

Electromagnetic pulse (EMP) radiation by laser interaction with a solid H2 ribbon

NASA Astrophysics Data System (ADS)

De Marco, M.; Krása, J.; Cikhardt, J.; Velyhan, A.; Pfeifer, M.; Dudžák, R.; Dostál, J.; Krouský, E.; Limpouch, J.; Pisarczyk, T.; Kalinowska, Z.; Chodukowski, T.; Ullschmied, J.; Giuffrida, L.; Chatain, D.; Perin, J.-P.; Margarone, D.

2017-08-01

The electromagnetic pulses (EMPs) generated during the interaction of a focused 1.315-μm sub-nanosecond laser pulse with a solid hydrogen ribbon were measured. The strength and temporal characteristics of EMPs were found to be dependent on the target density. If a low density target is ionized during the interaction with the laser, and the plasma does not physically touch the target holder, the EMP is weaker in strength and shorter in time duration. It is shown that during the H2 target experiment, the EMP does not strongly affect the response of fast electronic devices. The measurements of the EMP were carried out by Rohde&Schwarz B-Probes, particularly sensitive in the frequency range from 30 MHz and 1 GHz. Numerical simulations of resonant frequencies of the target chamber used in the experiment at the Prague Asterix Laser System kJ-class laser facility elucidate the peaked structure of EMP frequency spectra in the GHz domain.

Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru

2015-06-15

We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular tomore » an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.« less

Characterization of a 5-eV neutral atomic oxygen beam facility

NASA Technical Reports Server (NTRS)

Vaughn, J. A.; Linton, R. C.; Carruth, M. R., Jr.; Whitaker, A. F.; Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.

1991-01-01

An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm.

The interactions of solar arrays with electric thrusters

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Isaacson, G. C.; Domitz, S.

1976-01-01

The generation of a charge-exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma can be described accurately from thruster geometry and operating conditions. The transport of the charge-exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster-array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

Exploring novel structures for manipulating relativistic laser-plasma interaction

NASA Astrophysics Data System (ADS)

Ji, Liangliang

2016-10-01

The prospect of realizing compact particle accelerators and x-ray sources based on high power lasers has gained numerous attention. Utilization of all the proposed schemes in the field requires the laser-matter-interaction process to be repeatable or moreover, controllable. This has been very challenging at ultra-high light intensities due to the pre-pulse issue and the limitation on target manufacturing. With recent development on pulse cleaning technique, such as XPW and the use of plasma mirror, we now propose a novel approach that leverages recent advancements in 3D nano-printing of materials and high contrast lasers to manipulate the laser-matter interactions on the micro-scales. The current 3D direct laser-writing (DLW) technique can produce repeatable structures with at a resolution as high as 100 nm. Based on 3D PIC simulations, we explored two typical structures, the micro-cylinder and micro-tube targets. The former serves to enhance and control laser-electron acceleration and the latter is dedicated to manipulate relativistic light intensity. First principle-of-proof experiments were carried out in the SCARLET laser facility and confirmed some of our predictions on enhancing direct laser acceleration of electrons and ion acceleration. We believe that the use of the micro-structured elements provides another degree of freedom in LPI and these new results will open new paths towards micro-engineering interaction process that will benefit high field science, laser-based proton therapy, near-QED physics, and relativistic nonlinear optics. This work is supported by the AFOSR Basic Research Initiative (FA9550-14-1-0085).

ADX: a high field, high power density, advanced divertor and RF tokamak

NASA Astrophysics Data System (ADS)

LaBombard, B.; Marmar, E.; Irby, J.; Terry, J. L.; Vieira, R.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.; Baek, S.; Beck, W.; Bonoli, P.; Brunner, D.; Doody, J.; Ellis, R.; Ernst, D.; Fiore, C.; Freidberg, J. P.; Golfinopoulos, T.; Granetz, R.; Greenwald, M.; Hartwig, Z. S.; Hubbard, A.; Hughes, J. W.; Hutchinson, I. H.; Kessel, C.; Kotschenreuther, M.; Leccacorvi, R.; Lin, Y.; Lipschultz, B.; Mahajan, S.; Minervini, J.; Mumgaard, R.; Nygren, R.; Parker, R.; Poli, F.; Porkolab, M.; Reinke, M. L.; Rice, J.; Rognlien, T.; Rowan, W.; Shiraiwa, S.; Terry, D.; Theiler, C.; Titus, P.; Umansky, M.; Valanju, P.; Walk, J.; White, A.; Wilson, J. R.; Wright, G.; Zweben, S. J.

2015-05-01

The MIT Plasma Science and Fusion Center and collaborators are proposing a high-performance Advanced Divertor and RF tokamak eXperiment (ADX)—a tokamak specifically designed to address critical gaps in the world fusion research programme on the pathway to next-step devices: fusion nuclear science facility (FNSF), fusion pilot plant (FPP) and/or demonstration power plant (DEMO). This high-field (⩾6.5 T, 1.5 MA), high power density facility (P/S ˜ 1.5 MW m-2) will test innovative divertor ideas, including an ‘X-point target divertor’ concept, at the required performance parameters—reactor-level boundary plasma pressures, magnetic field strengths and parallel heat flux densities entering into the divertor region—while simultaneously producing high-performance core plasma conditions that are prototypical of a reactor: equilibrated and strongly coupled electrons and ions, regimes with low or no torque, and no fuelling from external heating and current drive systems. Equally important, the experimental platform will test innovative concepts for lower hybrid current drive and ion cyclotron range of frequency actuators with the unprecedented ability to deploy launch structures both on the low-magnetic-field side and the high-magnetic-field side—the latter being a location where energetic plasma-material interactions can be controlled and favourable RF wave physics leads to efficient current drive, current profile control, heating and flow drive. This triple combination—advanced divertors, advanced RF actuators, reactor-prototypical core plasma conditions—will enable ADX to explore enhanced core confinement physics, such as made possible by reversed central shear, using only the types of external drive systems that are considered viable for a fusion power plant. Such an integrated demonstration of high-performance core-divertor operation with steady-state sustainment would pave the way towards an attractive pilot plant, as envisioned in the ARC concept (affordable, robust, compact) (Sorbom et al 2015 Fusion Eng. Des. submitted (arXiv:1409.3540)) that makes use of high-temperature superconductor technology—a high-field (9.25 T) tokamak the size of the Joint European Torus that produces 270 MW of net electricity.

Plasma Propulsion Testing Capabilities at Arnold Engineering Development Center

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Dawbarn, Albert; Moeller, Trevor

2007-01-01

This paper describes the results of a series of experiments aimed at quantifying the plasma propulsion testing capabilities of a 12-ft diameter vacuum facility (12V) at USAF-Arnold Engineering Development Center (AEDC). Vacuum is maintained in the 12V facility by cryogenic panels lining the interior of the chamber. The pumping capability of these panels was shown to be great enough to support plasma thrusters operating at input electrical power >20 kW. In addition, a series of plasma diagnostics inside the chamber allowed for measurement of plasma parameters at different spatial locations, providing information regarding the chamber's effect on the global plasma thruster flowfield. The plasma source used in this experiment was Hall thruster manufactured by Busek Co. The thruster was operated at up to 20 kW steady-state power in both a lower current and higher current mode. The vacuum level in the chamber never rose above 9 x 10(exp -6) torr during the course of testing. Langmuir probes, ion flux probes, and Faraday cups were used to quantify the plasma parameters in the chamber. We present the results of these measurements and estimates of pumping speed based on the background pressure level and thruster propellant mass flow rate.

A review of laser-plasma interaction physics of indirect-drive fusion

NASA Astrophysics Data System (ADS)

Kirkwood, R. K.; Moody, J. D.; Kline, J.; Dewald, E.; Glenzer, S.; Divol, L.; Michel, P.; Hinkel, D.; Berger, R.; Williams, E.; Milovich, J.; Yin, L.; Rose, H.; MacGowan, B.; Landen, O.; Rosen, M.; Lindl, J.

2013-10-01

The National Ignition Facility (NIF) has been designed, constructed and has recently begun operation to investigate the ignition of nuclear fusion with a laser with up to 1.8 MJ of energy per pulse. The concept for fusion ignition on the NIF, as first proposed in 1990, was based on an indirectly driven spherical capsule of fuel in a high-Z hohlraum cavity filled with low-Z gas (Lindl et al 2004 Phys. Plasmas 11 339). The incident laser energy is converted to x-rays with keV energy on the hohlraums interior wall. The x-rays then impinge on the surface of the capsule, imploding it and producing the fuel conditions needed for ignition. It was recognized at the inception that this approach would potentially be susceptible to scattering of the incident light by the plasma created in the gas and the ablated material in the hohlraum interior. Prior to initial NIF operations, expectations for laser-plasma interaction (LPI) in ignition-scale experiments were based on experimentally benchmarked simulations and models of the plasma effects that had been carried out as part of the original proposal for NIF and expanded during the 13-year design and construction period. The studies developed the understanding of the stimulated Brillouin scatter, stimulated Raman scatter and filamentation that can be driven by the intense beams. These processes produce scatter primarily in both the forward and backward direction, and by both individual beams and collective interaction of multiple beams. Processes such as hot electron production and plasma formation and transport were also studied. The understanding of the processes so developed was the basis for the design and planning of the recent experiments in the ignition campaign at NIF, and not only indicated that the plasma instabilities could be controlled to maximize coupling, but predicted that, for the first time, they would be beneficial in controlling drive symmetry. The understanding is also now a critical component in the worldwide effort to produce a fusion energy source with a laser (Lindl et al 2011 Nucl. Fusion 51 094024, Collins et al 2012 Phys. Plasmas 19 056308) and has recently received its most critical test yet with the inception of the NIF experiments with ignition-scale indirect-drive targets (Landen et al 2010 Phys. Plasmas 17 056301, Edwards et al 2011 Phys. Plasmas 18 051003, Glenzer et al 2011 Phys. Rev. Lett. 106 085004, Haan et al 2011 Phys. Plasmas 18 051001, Landen et al 2011 Phys. Plasmas 18 051001, Lindl et al 2011 Nucl. Fusion 51 094024). In this paper, the data obtained in the first complete series of coupling experiments in ignition-scale hohlraums is reviewed and compared with the preceding work on the physics of LPIs with the goal of recognizing aspects of our understanding that are confirmed by these experiments and recognizing and motivating areas that need further modeling. Understanding these hohlraum coupling experiments is critical as they are only the first step in a campaign to study indirectly driven implosions under the conditions of ignition by inertial confinement at NIF, and in the near future they are likely to further influence ignition plans and experimental designs.

A numerical study of neutral-plasma interaction in magnetically confined plasmas

NASA Astrophysics Data System (ADS)

Taheri, S.; Shumlak, U.; King, J. R.

2017-10-01

Interactions between plasma and neutral species can have a large effect on the dynamic behavior of magnetically confined plasma devices, such as the edge region of tokamaks and the plasma formation of Z-pinches. The presence of neutrals can affect the stability of the pinch and change the dynamics of the pinch collapse, and they can lead to deposition of high energy particles on the first wall. However, plasma-neutral interactions can also have beneficial effects such as quenching the disruptions in tokamaks. In this research a reacting plasma-neutral model, which combines a magnetohydrodynamic (MHD) plasma model with a gas dynamic neutral fluid model, is used to study the interaction between plasma and neutral gas. Incorporating this model into NIMROD allows the study of electron-impact ionization, radiative recombination, and resonant charge-exchange in plasma-neutral systems. An accelerated plasma moving through a neutral gas background is modeled in both a parallel plate and a coaxial electrode configuration to explore the effect of neutral gas in pinch-like devices. This work is supported by a Grant from US DOE.

The Plasma Interaction Experiment (PIX) description and test program. [electrometers

NASA Technical Reports Server (NTRS)

Ignaczak, L. R.; Haley, F. A.; Domino, E. J.; Culp, D. H.; Shaker, F. J.

1978-01-01

The plasma interaction experiment (PIX) is a battery powered preprogrammed auxiliary payload on the LANDSAT-C launch. This experiment is part of a larger program to investigate space plasma interactions with spacecraft surfaces and components. The varying plasma densities encountered during available telemetry coverage periods are deemed sufficient to determine first order interactions between the space plasma environment and the biased experimental surfaces. The specific objectives of the PIX flight experiment are to measure the plasma coupling current and the negative voltage breakdown characteristics of a solar array segment and a gold plated steel disk. Measurements will be made over a range of surface voltages up to plus or minus kilovolt. The orbital environment will provide a range of plasma densities. The experimental surfaces will be voltage biased in a preprogrammed step sequence to optimize the data returned for each plasma region and for the available telemetry coverage.

Investigation of RF Emissions from Electric Field Dominated Plasmas

DTIC Science & Technology

1989-03-31

David Rosenberg and Mr. Paul D. Spence, "RF Plasma Emissions Measured with Calibrated, Broadband Antenna". February 19 Mr. Antonino Carnevali, Fusion...plasma equipment exhibitors, and major Japanese i fusion facilities. November 20 Dr. Antonino Carnevalli, RPI and Fusion Energy Division, ORNL: "H av Ion

Research on Heating, Instabilities, Turbulence and RF Emission from Electric Field Dominated Plasmas

DTIC Science & Technology

1989-07-01

Spence, "RF Plasma Emissions Measured with Calibrated, Broadband Antenna". February 19 Mr. Antonino Carnevali, Fusion Energy Division, ORNL,"Confinement...slides of the conference, plasma equipment exhibitors, and major Japanese fusion facilities. November 20 Dr. Antonino Carnevalli, RPI and Fusion Energy

Plasma wakefield acceleration experiments at FACET II

NASA Astrophysics Data System (ADS)

Joshi, C.; Adli, E.; An, W.; Clayton, C. E.; Corde, S.; Gessner, S.; Hogan, M. J.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; O'shea, B.; Xu, Xinlu; White, G.; Yakimenko, V.

2018-03-01

During the past two decades of research, the ultra-relativistic beam-driven plasma wakefield accelerator (PWFA) concept has achieved many significant milestones. These include the demonstration of ultra-high gradient acceleration of electrons over meter-scale plasma accelerator structures, efficient acceleration of a narrow energy spread electron bunch at high-gradients, positron acceleration using wakes in uniform plasmas and in hollow plasma channels, and demonstrating that highly nonlinear wakes in the ‘blow-out regime’ have the electric field structure necessary for preserving the emittance of the accelerating bunch. A new 10 GeV electron beam facility, Facilities for Accelerator Science and Experimental Test (FACET) II, is currently under construction at SLAC National Accelerator Laboratory for the next generation of PWFA research and development. The FACET II beams will enable the simultaneous demonstration of substantial energy gain of a small emittance electron bunch while demonstrating an efficient transfer of energy from the drive to the trailing bunch. In this paper we first describe the capabilities of the FACET II facility. We then describe a series of PWFA experiments supported by numerical and particle-in-cell simulations designed to demonstrate plasma wake generation where the drive beam is nearly depleted of its energy, high efficiency acceleration of the trailing bunch while doubling its energy and ultimately, quantifying the emittance growth in a single stage of a PWFA that has optimally designed matching sections. We then briefly discuss other FACET II plasma-based experiments including in situ positron generation and acceleration, and several schemes that are promising for generating sub-micron emittance bunches that will ultimately be needed for both an early application of a PWFA and for a plasma-based future linear collider.

Plasma wakefield acceleration experiments at FACET II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, C.; Adli, E.; An, W.

During the past two decades of research, the ultra-relativistic beam-driven plasma wakefield accelerator (PWFA) concept has achieved many significant milestones. These include the demonstration of ultra-high gradient acceleration of electrons over meter-scale plasma accelerator structures, efficient acceleration of a narrow energy spread electron bunch at high-gradients, positron acceleration using wakes in uniform plasmas and in hollow plasma channels, and demonstrating that highly nonlinear wakes in the 'blow-out regime' have the electric field structure necessary for preserving the emittance of the accelerating bunch. A new 10 GeV electron beam facility, Facilities for Accelerator Science and Experimental Test (FACET) II, is currentlymore » under construction at SLAC National Accelerator Laboratory for the next generation of PWFA research and development. The FACET II beams will enable the simultaneous demonstration of substantial energy gain of a small emittance electron bunch while demonstrating an efficient transfer of energy from the drive to the trailing bunch. In this paper we first describe the capabilities of the FACET II facility. We then describe a series of PWFA experiments supported by numerical and particle-in-cell simulations designed to demonstrate plasma wake generation where the drive beam is nearly depleted of its energy, high efficiency acceleration of the trailing bunch while doubling its energy and ultimately, quantifying the emittance growth in a single stage of a PWFA that has optimally designed matching sections. Here, we briefly discuss other FACET II plasma-based experiments including in situ positron generation and acceleration, and several schemes that are promising for generating sub-micron emittance bunches that will ultimately be needed for both an early application of a PWFA and for a plasma-based future linear collider.« less

Plasma wakefield acceleration experiments at FACET II

DOE PAGES

Joshi, C.; Adli, E.; An, W.; ...

2018-01-12

During the past two decades of research, the ultra-relativistic beam-driven plasma wakefield accelerator (PWFA) concept has achieved many significant milestones. These include the demonstration of ultra-high gradient acceleration of electrons over meter-scale plasma accelerator structures, efficient acceleration of a narrow energy spread electron bunch at high-gradients, positron acceleration using wakes in uniform plasmas and in hollow plasma channels, and demonstrating that highly nonlinear wakes in the 'blow-out regime' have the electric field structure necessary for preserving the emittance of the accelerating bunch. A new 10 GeV electron beam facility, Facilities for Accelerator Science and Experimental Test (FACET) II, is currentlymore » under construction at SLAC National Accelerator Laboratory for the next generation of PWFA research and development. The FACET II beams will enable the simultaneous demonstration of substantial energy gain of a small emittance electron bunch while demonstrating an efficient transfer of energy from the drive to the trailing bunch. In this paper we first describe the capabilities of the FACET II facility. We then describe a series of PWFA experiments supported by numerical and particle-in-cell simulations designed to demonstrate plasma wake generation where the drive beam is nearly depleted of its energy, high efficiency acceleration of the trailing bunch while doubling its energy and ultimately, quantifying the emittance growth in a single stage of a PWFA that has optimally designed matching sections. Here, we briefly discuss other FACET II plasma-based experiments including in situ positron generation and acceleration, and several schemes that are promising for generating sub-micron emittance bunches that will ultimately be needed for both an early application of a PWFA and for a plasma-based future linear collider.« less

Bringing Space Science to the Undergraduate Classroom: NASA's USIP Mission

NASA Astrophysics Data System (ADS)

Vassiliadis, D.; Christian, J. A.; Keesee, A. M.; Spencer, E. A.; Gross, J.; Lusk, G. D.

2015-12-01

As part of its participation in NASA's Undergraduate Student Instrument Project (USIP), a team of engineering and physics students at West Virginia University (WVU) built a series of sounding rocket and balloon missions. The first rocket and balloon missions were flown near-simultaneously in a campaign on June 26, 2014 (image). The second sounding rocket mission is scheduled for October 5, 2015. Students took a course on space science in spring 2014, and followup courses in physics and aerospace engineering departments have been developed since then. Guest payloads were flown from students affiliated with WV Wesleyan College, NASA's IV&V Facility, and the University of South Alabama. Students specialized in electrical and aerospace engineering, and space physics topics. They interacted regularly with NASA engineers, presented at telecons, and prepared reports. A number of students decided to pursue internships and/or jobs related to space science and technology. Outreach to the campus and broader community included demos and flight projects. The physics payload includes plasma density and temperature measurements using a Langmuir and a triple probe; plasma frequency measurements using a radio sounder (WVU) and an impedance probe (U.S.A); and a magnetometer (WVWC). The aerospace payload includes an IMU swarm, a GPS experiment (with TEC capability); a cubesat communications module (NASA IV&V), and basic flight dynamics. Acknowledgments: staff members at NASA Wallops Flight Facility, and at the Orbital-ATK Rocket Center, WV.

B{sub 4}C-SiC reaction-sintered coatings on graphite plasma facing components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valentine, P.G.; Trester, P.W.; Winter, J.

1994-05-01

Boron carbide plus silicon carbide (B{sub 4}C-SiC) reaction-sintered coatings for use on graphite plasma-facing components were developed. Such coatings are of interest in TEXTOR tokamak limiter-plasma interactions as a means of reducing carbon erosion, of providing a preferred release of boron for oxygen gettering, and of investigating silicon`s effect on radiative edge phenomena. Specimens evaluated had (a) either Ringsdorfwerke EK 98 graphite or Le Carbon Lorraine felt-type AEROLOR A05 CFC substrates; (b) multiphase coatings, comprised of B{sub 4}C, Sic, and graphite; (c) nominal coating compositions of 69 wt.-% B{sub 4}C + 31 wt.-% SiC; and (d) nominal coating thicknesses betweenmore » 250 and 775 {mu}m. Coated coupons were evaluated by high heat flux experiments in the JUDITH (electron beam) test facility at KFA. Simulated disruptions, with energy densities up to 10 MJm{sup {minus}2}, and normal operation simulations, with power densities up to 12 MWm{sup {minus}2}, were conducted. The coatings remained adherent; at the highest levels tested, minor changes occurred, including localized remelting, modification of the crystallographic phases, occasional microcracking, and erosion.« less

Characterization and Mitigation of ICRF Antenna - Plasma Edge Interaction

NASA Astrophysics Data System (ADS)

Hong, Rongjie; Tynan, George; Wukitch, Steve; Lin, Yijun; Terry, Jim; Chilenski, M.; Golfinopoulos, T.; Hubbard, A.; Mumgaard, R. T.; Perkins, R.; Reinke, M. L.; Alcator C-Mod Team

2017-10-01

Recent experiments reveal that RF-induced potentials (VRF) in the SOL and impurity source at the antenna can be reduced to background levels via optimizing the power ratio between the inner and outer current straps, Pcent /Pout . Experiments indicate the antenna impurity source reduction for the field aligned antenna is due to geometrical alignment rather than electrical symmetry. Additional experiments performed without an optimized Pcent /Pout showed that VRF and the associated convection cells do not influence the impurity penetration or core impurity confinement. These results suggest the core impurity contamination associated with ICRF heating is dominated by an increased impurity source rather than a change in impurity transport. Further, the convective cell strength was expected to scale inversely with B-field. The observed poloidal velocity (measure of convective cell strength), however, decreased less than expected. In addition, the measured maximum VRF increased and penetrated farther into the SOL at higher B-field and plasma current. Results also suggest VRF is strongly influenced by the SOL plasma parameters rather than by RF parameters. Work supported by the U.S. DoE, Office of Science, Office of Fusion Energy Sciences, User Facility Alcator C-Mod under DE-FC02-99ER54512 and DE-SC 0010720.

The National Ignition Facility: Transition to a User Facility

NASA Astrophysics Data System (ADS)

Moses, E. I.; Atherton, J.; Lagin, L.; Larson, D.; Keane, C.; MacGowan, B.; Patterson, R.; Spaeth, M.; Van Wonterghem, B.; Wegner, P.; Kauffman, R.

2016-03-01

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) has been operational since March 2009 and has been transitioning to a user facility supporting ignition science, high energy density science (HEDS), national security applications, and fundamental science. The facility has achieved its design goal of 1.8 MJ and 500 TW of 3ω light on target, and has performed target experiments with 1.9 MJ at peak powers of 410 TW. The facility is on track to perform over 200 target shots this year in support of all of its user communities. The facility has nearly 60 diagnostic systems operational and has shown flexibility in laser pulse shape and performance to meet the requirements of its multiple users. Progress continues on its goal of demonstrating thermonuclear burn in the laboratory. It has performed over 40 indirect-drive experiments with cryogenic-layered capsules. New platforms are being developed for HEDS and fundamental science. Equation-of-state and material strength experiments have been done on a number of materials with pressures of over 50 MBars obtained in diamond, conditions never previously encountered in the laboratory and similar to those found in planetary interiors. Experiments are also in progress investigating radiation transport, hydrodynamic instabilities, and direct drive implosions. NIF continues to develop as an experimental facility. Advanced Radiographic Capability (ARC) is now being installed on NIF for producing high-energy radiographs of the imploded cores of ignition targets and for short pulse laser-plasma interaction experiments. One NIF beam is planned for conversion to two picosecond beams in 2014. Other new diagnostics such as x-ray Thomson scattering, low energy neutron spectrometer, and multi-layer reflecting x-ray optics are also planned. Incremental improvements in laser performance such as improved optics damage performance, beam balance, and back reflection control are being pursued.

RF-Plasma Source Commissioning in Indian Negative Ion Facility

NASA Astrophysics Data System (ADS)

Singh, M. J.; Bandyopadhyay, M.; Bansal, G.; Gahlaut, A.; Soni, J.; Kumar, Sunil; Pandya, K.; Parmar, K. G.; Sonara, J.; Yadava, Ratnakar; Chakraborty, A. K.; Kraus, W.; Heinemann, B.; Riedl, R.; Obermayer, S.; Martens, C.; Franzen, P.; Fantz, U.

2011-09-01

The Indian program of the RF based negative ion source has started off with the commissioning of ROBIN, the inductively coupled RF based negative ion source facility under establishment at Institute for Plasma research (IPR), India. The facility is being developed under a technology transfer agreement with IPP Garching. It consists of a single RF driver based beam source (BATMAN replica) coupled to a 100 kW, 1 MHz RF generator with a self excited oscillator, through a matching network, for plasma production and ion extraction and acceleration. The delivery of the RF generator and the RF plasma source without the accelerator, has enabled initiation of plasma production experiments. The recent experimental campaign has established the matching circuit parameters that result in plasma production with density in the range of 0.5-1×1018/m3, at operational gas pressures ranging between 0.4-1 Pa. Various configurations of the matching network have been experimented upon to obtain a stable operation of the set up for RF powers ranging between 25-85 kW and pulse lengths ranging between 4-20 s. It has been observed that the range of the parameters of the matching circuit, over which the frequency of the power supply is stable, is narrow and further experiments with increased number of turns in the coil are in the pipeline to see if the range can be widened. In this paper, the description of the experimental system and the commissioning data related to the optimisation of the various parameters of the matching network, to obtain stable plasma of required density, are presented and discussed.

Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility

NASA Astrophysics Data System (ADS)

Woo, Hyun-Jong; Chung, Kyu-Sun; You, Hyun-Jong; Lee, Myoung-Jae; Lho, Taihyeop; Choh, Kwon Kook; Yoon, Jung-Sik; Jung, Yong Ho; Lee, Bongju; Yoo, Suk Jae; Kwon, Myeon

2007-10-01

A Multi-Purpose Plasma (MP2) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB6 (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB6 (HLA-LaB6) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB6 cathode is composed of the one inner cathode with 4in. diameter and the six outer cathodes with 2in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6×1012 cm-3, while the electron temperature remains around 3-3.5eV at the low discharge current of less than 45A, and the magnetic field intensity of 870G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB6 cathode with 4in. diameter in DiPS.

Honeycomblike large area LaB6 plasma source for Multi-Purpose Plasma facility.

PubMed

Woo, Hyun-Jong; Chung, Kyu-Sun; You, Hyun-Jong; Lee, Myoung-Jae; Lho, Taihyeop; Choh, Kwon Kook; Yoon, Jung-Sik; Jung, Yong Ho; Lee, Bongju; Yoo, Suk Jae; Kwon, Myeon

2007-10-01

A Multi-Purpose Plasma (MP(2)) facility has been renovated from Hanbit mirror device [Kwon et al., Nucl. Fusion 43, 686 (2003)] by adopting the same philosophy of diversified plasma simulator (DiPS) [Chung et al., Contrib. Plasma Phys. 46, 354 (2006)] by installing two plasma sources: LaB(6) (dc) and helicon (rf) plasma sources; and making three distinct simulators: divertor plasma simulator, space propulsion simulator, and astrophysics simulator. During the first renovation stage, a honeycomblike large area LaB(6) (HLA-LaB(6)) cathode was developed for the divertor plasma simulator to improve the resistance against the thermal shock fragility for large and high density plasma generation. A HLA-LaB(6) cathode is composed of the one inner cathode with 4 in. diameter and the six outer cathodes with 2 in. diameter along with separate graphite heaters. The first plasma is generated with Ar gas and its properties are measured by the electric probes with various discharge currents and magnetic field configurations. Plasma density at the middle of central cell reaches up to 2.6 x 10(12) cm(-3), while the electron temperature remains around 3-3.5 eV at the low discharge current of less than 45 A, and the magnetic field intensity of 870 G. Unique features of electric property of heaters, plasma density profiles, is explained comparing with those of single LaB(6) cathode with 4 in. diameter in DiPS.

Synergistic Tailoring of Electrostatic and Hydrophobic Interactions for Rapid and Specific Recognition of Lysophosphatidic Acid, an Early-Stage Ovarian Cancer Biomarker.

PubMed

Wang, Ying; Pei, Hanwen; Jia, Yan; Liu, Jianhua; Li, Zelun; Ai, Kelong; Lu, Zhongyuan; Lu, Lehui

2017-08-23

Early detection of ovarian cancer, the most lethal type of gynecologic cancer, can dramatically improve the efficacy of available treatment strategies. However, few screening tools exist for rapidly and effectively diagnosing ovarian cancer in early stages. Here, we present a facile "lock-key" strategy, based on rapid, specific detection of plasma lysophosphatidic acid (LPA, an early stage biomarker) with polydiacetylenes (PDAs)-based probe, for the early diagnosis of ovarian cancer. This strategy relies on specifically inserting LPA "key" into the PDAs "lock" through the synergistic electrostatic and hydrophobic interactions between them, leading to conformation transition of the PDA backbone with a concomitant blue-to-red color change. The detailed mechanism underlying the high selectivity of PDAs toward LPA is revealed by comprehensive theoretical calculation and experiments. Moreover, the level of LPA can be quantified in plasma samples from both mouse xenograft tumor models and patients with ovarian cancer. Impressively, this approach can be introduced into a portable point-of-care device to successfully distinguish the blood samples of patients with ovarian cancer from those of healthy people, with 100% accuracy. This work provides a valuable portable tool for early diagnosis of ovarian cancer and thus holds a great promise to dramatically improve the overall survival.

Electron energy distributions measured during electron beam/plasma interactions. [in E region

NASA Technical Reports Server (NTRS)

Jost, R. J.; Anderson, H. R.; Mcgarity, J. O.

1980-01-01

In the large vacuum facility at the NASA-Johnson Space Center an electron beam was projected 20 m parallel to B from a gun with variable accelerating potential (1.0 to 2.5 kV) to an aluminum target. The ionospheric neutral pressure and field were approximated. Beam electron energy distributions were measured directly using an electrostatic deflection analyzer and indirectly with a detector that responded to the X-rays produced by electron impact on the target. At low currents the distribution is sharply peaked at the acceleration potential. At high currents a beam plasma discharge occurs and electrons are redistributed in energy so that the former energy peak broadens to 10-15 percent FWHM with a strongly enhanced low energy tail. At the 10% of maximum point the energy spectrum ranges from less than 1/2 to 1.2 times the gun energy. The effect is qualitatively the same at all pitch angles and locations sampled.

Plasma-assisted interface engineering of boron nitride nanostructure films.

PubMed

Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

2014-10-28

Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.

LLE Review Quarterly Report (October - December 2007). Volume 113

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuegel, Jonathan D.

2007-12-01

This volume of the LLE Review, covering October–December 2007, features “High-Intensity Laser–Plasma Interactions in the Refluxing Limit,” by P. M. Nilson, W. Theobald, J. Myatt, C. Stoeckl, M. Storm, O. V. Gotchev, J. D. Zuegel, R. Betti, D. D. Meyerhofer, and T. C. Sangster. In this article (p. 1), the authors report on target experiments using the Multi-Terawatt (MTW) Laser Facility to study isochoric heating of solid-density targets by fast electrons produced from intense, short-pulse laser irradiation. Electron refluxing occurs due to target-sheath field effects and contains most of the fast electrons within the target volume. This efficiently heats themore » solid-density plasma through collisions. X-ray spectroscopic measurements of absolute K α (x-radiation) photon yields and variations of the K β/K α b emission ratio both indicate that laser energy couples to fast electrons with a conversion efficiency of approximately 20%. Bulk electron temperatures of at least 200 eV are inferred for the smallest mass targets.« less

Laser-driven ion acceleration at BELLA

NASA Astrophysics Data System (ADS)

Bin, Jianhui; Steinke, Sven; Ji, Qing; Nakamura, Kei; Treffert, Franziska; Bulanov, Stepan; Roth, Markus; Toth, Csaba; Schroeder, Carl; Esarey, Eric; Schenkel, Thomas; Leemans, Wim

2017-10-01

BELLA is a high repetiton rate PW laser and we used it for high intensity laser plasma acceleration experiments. The BELLA-i program is focused on relativistic laser plasma interaction such as laser driven ion acceleration, aiming at establishing an unique collaborative research facility providing beam time to selected external groups for fundamental physics and advanced applications. Here we present our first parameter study of ion acceleration driven by the BELLA-PW laser with truly high repetition rate. The laser repetition rate of 1Hz allows for scanning the laser pulse duration, relative focus location and target thickness for the first time at laser peak powers of above 1 PW. Furthermore, the long focal length geometry of the experiment (f ∖65) and hence, large focus size provided ion beams of reduced divergence and unprecedented charge density. This work was supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

NASA Astrophysics Data System (ADS)

Manuel, M. J.-E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; Drake, R. P.; Pollock, B. B.; Park, J.; Hazi, A. U.; Williams, G. J.; Chen, H.

2015-12-01

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. This result is a topic of ongoing investigation.

Understanding turbulence in compressing plasmas and its exploitation or prevention.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidovits, Seth

Unprecedented densities and temperatures are now achieved in compressions of plasma, by lasers and by pulsed power, in major experimental facilities. These compressions, carried out at the largest scale at the National Ignition Facility and at the Z Pulsed Power Facility, have important applications, including fusion, X-ray production, and materials research. Several experimental and simulation results suggest that the plasma in some of these compressions is turbulent. In fact, measurements suggest that in certain laboratory plasma compressions the turbulent energy is a dominant energy component. Similarly, turbulence is dominant in some compressing astrophysical plasmas, such as in molecular clouds. Turbulencemore » need not be dominant to be important; even small quantities could greatly influence experiments that are sensitive to mixing of non-fuel into fuel, such as compressions seeking fusion ignition. Despite its important role in major settings, bulk plasma turbulence under compression is insufficiently understood to answer or even to pose some of the most fundamental questions about it. This thesis both identifies and answers key questions in compressing turbulent motion, while providing a description of the behavior of three-dimensional, isotropic, compressions of homogeneous turbulence with a plasma viscosity. This description includes a simple, but successful, new model for the turbulent energy of plasma undergoing compression. The unique features of compressing turbulence with a plasma viscosity are shown, including the sensitivity of the turbulence to plasma ionization, and a sudden viscous dissipation'' effect which rapidly converts plasma turbulent energy into thermal energy. This thesis then examines turbulence in both laboratory compression experiments and molecular clouds. It importantly shows: the possibility of exploiting turbulence to make fusion or X-ray production more efficient; conditions under which hot-spot turbulence can be prevented; and a lower bound on the growth of turbulence in molecular clouds. This bound raises questions about the level of dissipation in existing molecular cloud models. Finally, the observations originally motivating the thesis, Z-pinch measurements suggesting dominant turbulent energy, are reexamined by self-consistently accounting for the impact of the turbulence on the spectroscopic analysis. This is found to strengthen the evidence that the multiple observations describe a highly turbulent plasma state.« less

Understanding Turbulence in Compressing Plasmas and Its Exploitation or Prevention

NASA Astrophysics Data System (ADS)

Davidovits, Seth

Unprecedented densities and temperatures are now achieved in compressions of plasma, by lasers and by pulsed power, in major experimental facilities. These compressions, carried out at the largest scale at the National Ignition Facility and at the Z Pulsed Power Facility, have important applications, including fusion, X-ray production, and materials research. Several experimental and simulation results suggest that the plasma in some of these compressions is turbulent. In fact, measurements suggest that in certain laboratory plasma compressions the turbulent energy is a dominant energy component. Similarly, turbulence is dominant in some compressing astrophysical plasmas, such as in molecular clouds. Turbulence need not be dominant to be important; even small quantities could greatly influence experiments that are sensitive to mixing of non-fuel into fuel, such as compressions seeking fusion ignition. Despite its important role in major settings, bulk plasma turbulence under compression is insufficiently understood to answer or even to pose some of the most fundamental questions about it. This thesis both identifies and answers key questions in compressing turbulent motion, while providing a description of the behavior of three-dimensional, isotropic, compressions of homogeneous turbulence with a plasma viscosity. This description includes a simple, but successful, new model for the turbulent energy of plasma undergoing compression. The unique features of compressing turbulence with a plasma viscosity are shown, including the sensitivity of the turbulence to plasma ionization, and a "sudden viscous dissipation'' effect which rapidly converts plasma turbulent energy into thermal energy. This thesis then examines turbulence in both laboratory compression experiments and molecular clouds. It importantly shows: the possibility of exploiting turbulence to make fusion or X-ray production more efficient; conditions under which hot-spot turbulence can be prevented; and a lower bound on the growth of turbulence in molecular clouds. This bound raises questions about the level of dissipation in existing molecular cloud models. Finally, the observations originally motivating the thesis, Z-pinch measurements suggesting dominant turbulent energy, are reexamined by self-consistently accounting for the impact of the turbulence on the spectroscopic analysis. This is found to strengthen the evidence that the multiple observations describe a highly turbulent plasma state.

Bremsstrahlung Dose Yield for High-Intensity Short-Pulse Laser–Solid Experiments

DOE PAGES

Liang, Taiee; Bauer, Johannes M.; Liu, James C.; ...

2016-12-01

A bremsstrahlung source term has been developed by the Radiation Protection (RP) group at SLAC National Accelerator Laboratory for high-intensity short-pulse laser–solid experiments between 10 17 and 10 22 W cm –2. This source term couples the particle-in-cell plasma code EPOCH and the radiation transport code FLUKA to estimate the bremsstrahlung dose yield from laser–solid interactions. EPOCH characterizes the energy distribution, angular distribution, and laser-to-electron conversion efficiency of the hot electrons from laser–solid interactions, and FLUKA utilizes this hot electron source term to calculate a bremsstrahlung dose yield (mSv per J of laser energy on target). The goal of thismore » paper is to provide RP guidelines and hazard analysis for high-intensity laser facilities. In conclusion, a comparison of the calculated bremsstrahlung dose yields to radiation measurement data is also made.« less

Report of the Plasma Physics and Environmental Perturbation Laboratory (PPEPL) working groups. Volume 2: Wave experiments working group

NASA Technical Reports Server (NTRS)

1974-01-01

The area of wave experiments for the PPEPL is considered in broad terms. It was found that most experiments in this area can be classified typically by a few generalized experiments. These experiment possibilities are discussed in terms of advantages, disadvantages, and probable areas for future investigation. It was concluded that the areas where wave experiments have the most promise are wave sources, wave propagation, and nonlinear interactions and should be implemented in that order. It was recommended that the PPEPL facility remain sufficiently flexible to handle new ideas as they appear, and a continuing effort should be made to solicit new ideas and approaches. It was also felt that detailed investigations should begin as soon as possible in the areas of antennas, both conventional and particle types, and wave-particle interaction experiments. For Vol. 1, see N74-28169; for Vol. 3, see N74-28171.

Bremsstrahlung Dose Yield for High-Intensity Short-Pulse Laser–Solid Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Taiee; Bauer, Johannes M.; Liu, James C.

A bremsstrahlung source term has been developed by the Radiation Protection (RP) group at SLAC National Accelerator Laboratory for high-intensity short-pulse laser–solid experiments between 10 17 and 10 22 W cm –2. This source term couples the particle-in-cell plasma code EPOCH and the radiation transport code FLUKA to estimate the bremsstrahlung dose yield from laser–solid interactions. EPOCH characterizes the energy distribution, angular distribution, and laser-to-electron conversion efficiency of the hot electrons from laser–solid interactions, and FLUKA utilizes this hot electron source term to calculate a bremsstrahlung dose yield (mSv per J of laser energy on target). The goal of thismore » paper is to provide RP guidelines and hazard analysis for high-intensity laser facilities. In conclusion, a comparison of the calculated bremsstrahlung dose yields to radiation measurement data is also made.« less

EBIT - Electronic Beam Ion Trap: N Divison experimental physics annual report 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schneider, D.

1996-10-01

The multi-faceted research effort of the EBIT (Electron Beam Ion Trap) program in N-Division of the Physics and Space Technology Department at Lawrence Livermore National Laboratory (LLNL) continues to contribute significant results to the physical sciences from studies with low energy very highly charged heavy ions. The EBIT program attracts a number of collaborators from the US and abroad for the different projects. The collaborations are partly carried out through participating graduate students demonstrating the excellent educational capabilities at the LLNL EBIT facilities. Moreover, participants from Historically Black Colleges and Universities are engaged in the EBIT project. This report describesmore » EBIT work for 1995 in atomic structure measurements and radiative transition probabilities, spectral diagnostics for laboratory and astrophysical plasmas, ion/surface interaction studies, electron-ion interactions studies, retrap and ion collisions, and instrumental development.« less

Investigation of the boundary layer during the transition from volume to surface dominated H- production at the BATMAN test facility

NASA Astrophysics Data System (ADS)

Wimmer, C.; Schiesko, L.; Fantz, U.

2016-02-01

BATMAN (Bavarian Test Machine for Negative ions) is a test facility equipped with a 1/8 scale H- source for the ITER heating neutral beam injection. Several diagnostics in the boundary layer close to the plasma grid (first grid of the accelerator system) followed the transition from volume to surface dominated H- production starting with a Cs-free, cleaned source and subsequent evaporation of caesium, while the source has been operated at ITER relevant pressure of 0.3 Pa: Langmuir probes are used to determine the plasma potential, optical emission spectroscopy is used to follow the caesiation process, and cavity ring-down spectroscopy allows for the measurement of the H- density. The influence on the plasma during the transition from an electron-ion plasma towards an ion-ion plasma, in which negative hydrogen ions become the dominant negatively charged particle species, is seen in a strong increase of the H- density combined with a reduction of the plasma potential. A clear correlation of the extracted current densities (jH-, je) exists with the Cs emission.

Investigation of the boundary layer during the transition from volume to surface dominated H⁻ production at the BATMAN test facility.

PubMed

Wimmer, C; Schiesko, L; Fantz, U

2016-02-01

BATMAN (Bavarian Test Machine for Negative ions) is a test facility equipped with a 18 scale H(-) source for the ITER heating neutral beam injection. Several diagnostics in the boundary layer close to the plasma grid (first grid of the accelerator system) followed the transition from volume to surface dominated H(-) production starting with a Cs-free, cleaned source and subsequent evaporation of caesium, while the source has been operated at ITER relevant pressure of 0.3 Pa: Langmuir probes are used to determine the plasma potential, optical emission spectroscopy is used to follow the caesiation process, and cavity ring-down spectroscopy allows for the measurement of the H(-) density. The influence on the plasma during the transition from an electron-ion plasma towards an ion-ion plasma, in which negative hydrogen ions become the dominant negatively charged particle species, is seen in a strong increase of the H(-) density combined with a reduction of the plasma potential. A clear correlation of the extracted current densities (j(H(-)), j(e)) exists with the Cs emission.

Conceptual design of Dipole Research Experiment (DREX)

NASA Astrophysics Data System (ADS)

Xiao, Qingmei; Wang, Zhibin; Wang, Xiaogang; Xiao, Chijie; Yang, Xiaoyi; Zheng, Jinxing

2017-03-01

A new terrella-like device for laboratory simulation of inner magnetosphere plasmas, Dipole Research Experiment, is scheduled to be built at the Harbin Institute of Technology (HIT), China, as a major state scientific research facility for space physics studies. It is designed to provide a ground experimental platform to reproduce the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration. The scaling relation of hydromagnetism between the laboratory plasma of the device and the geomagnetosphere plasma is applied to resemble geospace processes in the Dipole Research Experiment plasma. Multiple plasma sources, different kinds of coils with specific functions, and advanced diagnostics are designed to be equipped in the facility for multi-functions. The motivation, design criteria for the Dipole Research Experiment experiments and the means applied to generate the plasma of desired parameters in the laboratory are also described. Supported by National Natural Science Foundation of China (Nos. 11505040, 11261140326 and 11405038), China Postdoctoral Science Foundation (Nos. 2016M591518, 2015M570283) and Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (No. 2017008).

Laboratory simulation of the interaction between a tethered satellite system and the ionosphere

NASA Astrophysics Data System (ADS)

Vannaroni, G.; Giovi, R.; de Venuto, F.

1992-10-01

The authors report on the measurements performed in the IFSI/CNR plasma chamber at Frascati related to the laboratory investigation of the interaction between a plasma source and an ambient plasma of ionospheric type. Such an interaction is of relevant interest for the possibility of using electrodynamic tethered satellite systems, orbiting at ionospheric altitude, for generating electric power or propulsion in space. The interaction region was analyzed at various conditions of ambient magnetic field (/0-0.5/ G) and at different polarization levels of the plasma source (/0-40/ V). The plasma measurements were carried out with a diagnostic system using an array of Langmuir probes movable in the chamber so that a map of the plasma parameters could be obtained at the different experimental conditions.

Plasma-wall interaction in laser inertial fusion reactors: novel proposals for radiation tests of first wall materials

NASA Astrophysics Data System (ADS)

Alvarez Ruiz, J.; Rivera, A.; Mima, K.; Garoz, D.; Gonzalez-Arrabal, R.; Gordillo, N.; Fuchs, J.; Tanaka, K.; Fernández, I.; Briones, F.; Perlado, J.

2012-12-01

Dry-wall laser inertial fusion (LIF) chambers will have to withstand strong bursts of fast charged particles which will deposit tens of kJ m-2 and implant more than 1018 particles m-2 in a few microseconds at a repetition rate of some Hz. Large chamber dimensions and resistant plasma-facing materials must be combined to guarantee the chamber performance as long as possible under the expected threats: heating, fatigue, cracking, formation of defects, retention of light species, swelling and erosion. Current and novel radiation resistant materials for the first wall need to be validated under realistic conditions. However, at present there is a lack of facilities which can reproduce such ion environments. This contribution proposes the use of ultra-intense lasers and high-intense pulsed ion beams (HIPIB) to recreate the plasma conditions in LIF reactors. By target normal sheath acceleration, ultra-intense lasers can generate very short and energetic ion pulses with a spectral distribution similar to that of the inertial fusion ion bursts, suitable to validate fusion materials and to investigate the barely known propagation of those bursts through background plasmas/gases present in the reactor chamber. HIPIB technologies, initially developed for inertial fusion driver systems, provide huge intensity pulses which meet the irradiation conditions expected in the first wall of LIF chambers and thus can be used for the validation of materials too.

Parametric dependence of ion temperature and relative density in the NASA Lewis SUMMA facility. [superconducting magnetic mirror

NASA Technical Reports Server (NTRS)

Snyder, A.; Lauver, M. R.; Patch, R. W.

1976-01-01

Further hot-ion plasma experiments were conducted in the SUMMA superconducting magnetic mirror facility. A steady-state ExB plasma was formed by applying a strong radially inward dc electric field between cylindrical anodes and hollow cathodes located near the magnetic mirror maxima. Extending the use of water cooling to the hollow cathodes, in addition to the anodes, resulted in higher maximum power input to the plasma. Steady-state hydrogen plasmas with ion kinetic temperatures as high as 830 eV were produced. Functional relations were obtained empirically among the plasma current, voltage, magnetic flux density, ion temperature, and relative ion density. The functional relations were deduced by use of a multiple correlation analysis. Data were obtained for midplane magnetic fields from 0.5 to 3.37 tesla and input power up to 45 kW. Also, initial absolute electron density measurements are reported from a 90 deg Thomson scattering laser system.

Numerical implementation of a cold-ion, Boltzmann-electron model for nonplanar plasma-surface interactions

NASA Astrophysics Data System (ADS)

Holgate, J. T.; Coppins, M.

2018-04-01

Plasma-surface interactions are ubiquitous in the field of plasma science and technology. Much of the physics of these interactions can be captured with a simple model comprising a cold ion fluid and electrons which satisfy the Boltzmann relation. However, this model permits analytical solutions in a very limited number of cases. This paper presents a versatile and robust numerical implementation of the model for arbitrary surface geometries in cartesian and axisymmetric cylindrical coordinates. Specific examples of surfaces with sinusoidal corrugations, trenches, and hemi-ellipsoidal protrusions verify this numerical implementation. The application of the code to problems involving plasma-liquid interactions, plasma etching, and electron emission from the surface is discussed.

Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karles Fellowship

DTIC Science & Technology

2015-11-30

Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--15-9650 Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL... Plasma Physics Division i REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 3. DATES COVERED (From - To) Standard Form 298 (Rev. 8-98...ABSTRACT Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karle’s Fellowship Sandra (Hernandez) Hangarter Naval Research Laboratory 4555

Impact of combined hydrogen plasma and transient heat loads on the performance of tungsten as plasma facing material

NASA Astrophysics Data System (ADS)

Wirtz, M.; Bardin, S.; Huber, A.; Kreter, A.; Linke, J.; Morgan, T. W.; Pintsuk, G.; Reinhart, M.; Sergienko, G.; Steudel, I.; De Temmerman, G.; Unterberg, B.

2015-11-01

Experiments were performed in three different facilities in order to investigate the impact of combined steady state deuterium plasma exposure and ELM-like thermal shock events on the performance of ultra high purity tungsten. The electron beam facility JUDITH 1 was used to simulate pure thermal loads. In addition the linear plasma devices PSI-2 and Pilot-PSI have been used for successive as well as simultaneous exposure where the transient heat loads were applied by a high energy laser and the pulsed plasma operation, respectively. The results show that the damage behaviour strongly depends on the loading conditions and the sequence of the particle and heat flux exposure. This is due to hydrogen embrittlement and/or a higher defect concentration in the tungsten near surface region due to supersaturation of hydrogen. The different results in terms of damage formation from both linear plasma devices indicate that also the plasma parameters such as particle energy, flux and fluence, plasma impurities and the pulse shape have a strong influence on the damage performance. In addition, the different loading methods such as the scanning with the electron beam in contrast to the homogeneous exposure by the laser leads to an faster increase of the surface roughness due to plastic deformation.

The plasma dynamics of hypersonic spacecraft: Applications of laboratory simulations and active in situ experiments

NASA Technical Reports Server (NTRS)

Stone, N. H.; Samir, Uri

1986-01-01

Attempts to gain an understanding of spacecraft plasma dynamics via experimental investigation of the interaction between artificially synthesized, collisionless, flowing plasmas and laboratory test bodies date back to the early 1960's. In the past 25 years, a number of researchers have succeeded in simulating certain limited aspects of the complex spacecraft-space plasma interaction reasonably well. Theoretical treatments have also provided limited models of the phenomena. Several active experiments were recently conducted from the space shuttle that specifically attempted to observe the Orbiter-ionospheric interaction. These experiments have contributed greatly to an appreciation for the complexity of spacecraft-space plasma interaction but, so far, have answered few questions. Therefore, even though the plasma dynamics of hypersonic spacecraft is fundamental to space technology, it remains largely an open issue. A brief overview is provided of the primary results from previous ground-based experimental investigations and the preliminary results of investigations conducted on the STS-3 and Spacelab 2 missions. In addition, several, as yet unexplained, aspects of the spacecraft-space plasma interaction are suggested for future research.

Developing the science and technology for the Material Plasma Exposure eXperiment

DOE PAGES

Rapp, J.; Biewer, T. M.; Bigelow, T. S.; ...

2017-07-27

Linear plasma generators are cost effective facilities to simulate divertor plasma conditions of present and future fusion reactors. They are used to address important R&D gaps in the science of plasma material interactions and towards viable plasma facing components for fusion reactors. Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The steady-state linear plasma device MPEX will address this regime with electron temperatures of 1–10 eV and electron densities ofmore » $$10^{21}{\\text{}}\\!-\\!10^{20}$$ $${\\rm m}^{-3}$$. The resulting heat fluxes are about 10 MW $${\\rm m}^{-2}$$ . MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with electron Bernstein wave (EBW) heating and ion cyclotron resonance heating with a total installed power of 800 kW. The linear device Proto-MPEX, forerunner of MPEX consisting of 12 water-cooled copper coils, has been operational since May 2014. Its helicon antenna (100 kW, 13.56 MHz) and EC heating systems (200 kW, 28 GHz) have been commissioned and 14 MW $${\\rm m}^{-2}$$ was delivered on target. Furthermore, electron temperatures of about 20 eV have been achieved in combined helicon and ECH heating schemes at low electron densities. Overdense heating with EBW was achieved at low heating powers. The operational space of the density production by the helicon antenna was pushed up to $$1.1 \\times 10^{20}$$ $${\\rm m}^{-3}$$ at high magnetic fields of 1.0 T at the target. Finally, the experimental results from Proto-MPEX will be used for code validation to enable predictions of the source and heating performance for MPEX. MPEX, in its last phase, will be capable to expose neutron-irradiated samples. In this concept, targets will be irradiated in ORNL's High Flux Isotope Reactor and then subsequently exposed to fusion reactor relevant plasmas in MPEX.« less

Developing the science and technology for the Material Plasma Exposure eXperiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, J.; Biewer, T. M.; Bigelow, T. S.

Linear plasma generators are cost effective facilities to simulate divertor plasma conditions of present and future fusion reactors. They are used to address important R&D gaps in the science of plasma material interactions and towards viable plasma facing components for fusion reactors. Next generation plasma generators have to be able to access the plasma conditions expected on the divertor targets in ITER and future devices. The steady-state linear plasma device MPEX will address this regime with electron temperatures of 1–10 eV and electron densities ofmore » $$10^{21}{\\text{}}\\!-\\!10^{20}$$ $${\\rm m}^{-3}$$. The resulting heat fluxes are about 10 MW $${\\rm m}^{-2}$$ . MPEX is designed to deliver those plasma conditions with a novel Radio Frequency plasma source able to produce high density plasmas and heat electron and ions separately with electron Bernstein wave (EBW) heating and ion cyclotron resonance heating with a total installed power of 800 kW. The linear device Proto-MPEX, forerunner of MPEX consisting of 12 water-cooled copper coils, has been operational since May 2014. Its helicon antenna (100 kW, 13.56 MHz) and EC heating systems (200 kW, 28 GHz) have been commissioned and 14 MW $${\\rm m}^{-2}$$ was delivered on target. Furthermore, electron temperatures of about 20 eV have been achieved in combined helicon and ECH heating schemes at low electron densities. Overdense heating with EBW was achieved at low heating powers. The operational space of the density production by the helicon antenna was pushed up to $$1.1 \\times 10^{20}$$ $${\\rm m}^{-3}$$ at high magnetic fields of 1.0 T at the target. Finally, the experimental results from Proto-MPEX will be used for code validation to enable predictions of the source and heating performance for MPEX. MPEX, in its last phase, will be capable to expose neutron-irradiated samples. In this concept, targets will be irradiated in ORNL's High Flux Isotope Reactor and then subsequently exposed to fusion reactor relevant plasmas in MPEX.« less

Tokamak DEMO-FNS: Concept of magnet system and vacuum chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azizov, E. A., E-mail: Azizov-EA@nrcki.ru; Ananyev, S. S.; Belyakov, V. A.

The level of knowledge accumulated to date in the physics and technologies of controlled thermonuclear fusion (CTF) makes it possible to begin designing fusion—fission hybrid systems that would involve a fusion neutron source (FNS) and which would admit employment for the production of fissile materials and for the transmutation of spent nuclear fuel. Modern Russian strategies for CTF development plan the construction to 2023 of tokamak-based demonstration hybrid FNS for implementing steady-state plasma burning, testing hybrid blankets, and evolving nuclear technologies. Work on designing the DEMO-FNS facility is still in its infancy. The Efremov Institute began designing its magnet systemmore » and vacuum chamber, while the Kurchatov Institute developed plasma-physics design aspects and determined basic parameters of the facility. The major radius of the plasma in the DEMO-FNS facility is R = 2.75 m, while its minor radius is a = 1 m; the plasma elongation is k{sub 95} = 2. The fusion power is P{sub FUS} = 40 MW. The toroidal magnetic field on the plasma-filament axis is B{sub t0} = 5 T. The plasma current is I{sub p} = 5 MA. The application of superconductors in the magnet system permits drastically reducing the power consumed by its magnets but requires arranging a thick radiation shield between the plasma and magnet system. The central solenoid, toroidal-field coils, and poloidal-field coils are manufactured from, respectively, Nb{sub 3}Sn, NbTi and Nb{sub 3}Sn, and NbTi. The vacuum chamber is a double-wall vessel. The space between the walls manufactured from 316L austenitic steel is filled with an iron—water radiation shield (70% of stainless steel and 30% of water).« less

Studies of Plasma Instability Processes Excited by Ground Based High Power HF (Heating) Facilities

DTIC Science & Technology

2001-04-01

and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility (Peterson...Haslett and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility

Interaction of 1.05 μm and 0.53 μm lasers with gold disks

NASA Astrophysics Data System (ADS)

Shenye, Liu; Yaonan, Ding; Zhijian, Zheng; Daoyuan, Tang

1996-05-01

Gold disks were irradiated with 1.05 μm and 0.53 μm lasers at pulse duration of ˜0.8 ns, intensity ranging from 5×1013 W/cm2 to 4×1015 W/cm2 on the SHEN GUANG I laser facility in China. The experimental results of laser absorption, scattering light, x-ray emission and plasma blow-off are presented in this paper. When the laser irradiated the gold disk obliquely, the angular distribution of scattered lights produced by 0.53 μm lasers disagree with that predicted by the Brillouin scattering theory. The angular distribution is different from that reported previously by the others.

Effect of Background Pressure on the Plasma Oscillation Characteristics of the HiVHAc Hall Thruster

DTIC Science & Technology

2014-06-01

Hall thruster , a number of plasma diagnostics were implemented to study the effect of varying facility background pressure on thruster operation. These diagnostics characterized the thruster performance, the plume, and the plasma oscillations in the thruster. Thruster performance and plume characteristics as functions of background pressure were previously published. This paper will focus on changes in the plasma oscillation characteristics with changing background pressure. The diagnostics used to study plasma oscillations include a high-speed camera and a set of

Preface

NASA Astrophysics Data System (ADS)

Gauthier, Jean-Claude; Hammel, Bruce; Azechi, Hiroshi; Labaune, Christine

2006-06-01

The Fourth International Conference on Inertial Fusion Sciences and Applications (IFSA 2005) was held September 4-9, 2005 at the Bellevue Conference Center in Biarritz, France. The host organizations for this conference were the University of Bordeaux 1, the Centre National de la Recherche Scientifique (CNRS) and the Commissariat a l'Energie Atomique (CEA). The conference objective was to review of the state of the art of research in inertial fusion sciences and applications since the last conference held in Monterey California, USA, in 2003. Altogether 509 abstracts were submitted, 418 accepted, and more than 440 persons from 23 countries attended the conference. These Proceedings contain 249 of the papers presented at IFSA 2005. This collection of papers represents the manuscripts submitted to and passing the peer review process. The IFSA 2005 conference is the first of a new series of three conferences to be organized in France, Japan and the USA and governed under Annex I of the Memorandum of Agreement, signed in June 2004, among the Lawrence Livermore Laboratory operated by the University of California (UC), Osaka University, and Institut Lasers et Plasmas (ILP), operated by CNRS Delegation Aquitaine. The IFSA 2005 continued the strong tradition of the three previous conferences in Bordeaux, Kyoto and Monterey. It was the largest IFSA yet with a substantial participation from countries such as China and Russia. With a goal of achieving inertial fusion ignition and burn propagation in the laboratory, there continues to be significant progress in the international inertial fusion community. At IFSA 2005, researchers presented the exciting advances in traditional hot spot ignition approach, including results from the early experiments from the NIF laser. A particularly emphasis of the meeting was the rapid and exciting progress in the fast ignition scheme. Integrated and basic physics experiments on GekkoXII, Vulcan, and other laser-matter interaction facilities have shown promising results. A lot of new results of experiments and numerical simulations in ultra-intense laser interactions have also been presented. The Megajoule Laser (LMJ), as one of two facilities being built to achieve target ignition, was a key attraction of IFSA 2005. About 200 participants toured the LMJ construction site and the LIL laser prototype during the conference. Before the tour, a special Facility Focus session examined progress on inertial fusion facilities around the world, including the soon-to-be-completed OMEGA-EP upgrade at Rochester, USA, and FIREX I, at Osaka, Japan. Recent progresses in hohlraum physics continue to give confidence in the ultimate achievement of ignition on the NIF Laser and the Megajoule Laser. The USA are pursuing a very focused program on ICF under the National Ignition Campaign (NIC). In China, a national project has been launched, the goal of which is fusion ignition and plasma burning in about 2020. Progress in direct drive has been notable over the past few years with the cryogenic implosions at LLE, polar direct-drive that may enable to switch rapidly from an indirect- to a direct-drive laser configuration, adiabat shaping of laser pulses, and even "Saturn targets", a short circuit topic from ICF to laboratory astrophysics. About this last topic, radiative shocks and plasma jets were among the most studied subjects. There were also sessions on the technologies of al1 types of drivers, including KrF and DPSSL lasers, particle beams, and Z-pinches. Advances in Z-pinch included double-hohlraum irradiation symmetry and the construction of a PW laser beam for the Z-facility. Advance in plasma diagnostics were dominated by proton imaging from ultra-intense interactions and precise imaging spectroscopy of core implosions. Of special interest, advanced target physics and reactor design studies have started to be more present during this IFSA edition. These Proceedings start with special chapters on the keynote speeches and the Teller lectures. The keynotes give an overview of progress in inertial fusion in North America, Europe and Asia. The Teller lectures show the contributions of this year's two winners: Joe Kilkenny of General Atomics and Max Tabak of LLNL. The remainder of the Proceedings is divided into three parts. Part A covers the physics of inertial fusion; Part B covers facilities, lasers, particle beams, Z-pinches, target fabrication and reactor design; Part C covers fundamental high-energy density science and other applications of inertial fusion VI technology such as plasma diagnostics, atomic physics and X-ray sources, laboratory astrophysics and laser particle acceleration. The readers should be aware that for some of the papers, only a short version is presented in this book: the extended version will be published in a topical issue of the European Physical Journal. The IFSA International Organizing Committee and Scientific Advisory Board appreciate the efforts of inertial fusion researchers worldwide in making IFSA 2005 an extremely successful conference. Jean-Claude Gauthier, technical committee co-chair Bruce Hammel, technical committee co-chair Hiroshi Azechi, technical committee co-chair Christine Labaune, proceedings co-editor

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

DOE PAGES

Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.; ...

2014-08-20

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysicalmore » systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.« less

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysicalmore » systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.« less

Atomic Oxygen Lamp Cleaning Facility Fabricated and Tested

NASA Technical Reports Server (NTRS)

Sechkar, Edward A.; Stueber, Thomas J.

1999-01-01

NASA Lewis Research Center's Atomic Oxygen Lamp Cleaning Facility was designed to produce an atomic oxygen plasma within a metal halide lamp to remove carbon-based contamination. It is believed that these contaminants contribute to the high failure rate realized during the production of these lamps. The facility is designed to evacuate a metal halide lamp and produce a radio frequency generated atomic oxygen plasma within it. Oxygen gas, with a purity of 0.9999 percent and in the pressure range of 150 to 250 mtorr, is used in the lamp for plasma generation while the lamp is being cleaned. After cleaning is complete, the lamp can be backfilled with 0.9999-percent pure nitrogen and torch sealed. The facility comprises various vacuum components connected to a radiation-shielded box that encloses the bulb during operation. Radiofrequency power is applied to the two parallel plates of a capacitor, which are on either side of the lamp. The vacuum pump used, a Leybold Trivac Type D4B, has a pumping speed of 4-m3/hr, has an ultimate pressure of <8x10-4, and is specially adapted for pure oxygen service. The electronic power supply, matching network, and controller (500-W, 13.56-MHz) used to supply the radiofrequency power were purchased from RF Power Products Inc. Initial test results revealed that this facility could remove the carbon-based contamination from within bulbs.

Initial design for an experimental investigation of strongly coupled plasma behavior in the Atlas facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Munson, C.P.; Benage, J.F. Jr.; Taylor, A.J.

Atlas is a high current ({approximately} 30 MA peak, with a current risetime {approximately} 4.5 {micro}sec), high energy (E{sub stored} = 24 MJ, E{sub load} = 3--6 MJ), pulsed power facility which is being constructed at Los Alamos National Laboratory with a scheduled completion date in the year 2000. When operational, this facility will provide a platform for experiments in high pressure shocks (> 20 Mbar), adiabatic compression ({rho}/{rho}{sub 0} > 5, P > 10 Mbar), high magnetic fields ({approximately} 2,000 T), high strain and strain rates ({var_epsilon} > 200%, d{var_epsilon}/dt {approximately} 10{sup 4} to 10{sup 6} s{sup {minus}1}), hydrodynamicmore » instabilities of materials in turbulent regimes, magnetized target fusion, equation of state, and strongly coupled plasmas. For the strongly coupled plasma experiments, an auxiliary capacitor bank will be used to generate a moderate density (< 0.1 solid), relatively cold ({approximately} 1 eV) plasma by ohmic heating of a conducting material of interest such as titanium. This stargate plasma will be compressed against a central column containing diagnostic instrumentation by a cylindrical conducting liner that is driven radially inward by current from the main Atlas capacitor bank. The plasma is predicted to reach densities of {approximately} 1.1 times solid, achieve ion and electron temperatures of {approximately} 10 eV, and pressures of {approximately} 4--5 Mbar. This is a density/temperature regime which is expected to experience strong coupling, but only partial degeneracy. X-ray radiography is planned for measurements of the material density at discrete times during the experiments; diamond Raman measurements are anticipated for determination of the pressure. In addition, a neutron resonance spectroscopic technique is being evaluated for possible determination of the temperature (through low percentage doping of the titanium with a suitable resonant material). Initial target plasma formation experiments are being planned on an existing pulsed power facility at LANL and will be completed before the start of operation of Atlas.« less

The INAF/IAPS Plasma Chamber for ionospheric simulation experiment

NASA Astrophysics Data System (ADS)

Diego, Piero

2016-04-01

The plasma chamber is particularly suitable to perform studies for the following applications: - plasma compatibility and functional tests on payloads envisioned to operate in the ionosphere (e.g. sensors onboard satellites, exposed to the external plasma environment); - calibration/testing of plasma diagnostic sensors; - characterization and compatibility tests on components for space applications (e.g. optical elements, harness, satellite paints, photo-voltaic cells, etc.); - experiments on satellite charging in a space plasma environment; - tests on active experiments which use ion, electron or plasma sources (ion thrusters, hollow cathodes, field effect emitters, plasma contactors, etc.); - possible studies relevant to fundamental space plasma physics. The facility consists of a large volume vacuum tank (a cylinder of length 4.5 m and diameter 1.7 m) equipped with a Kaufman type plasma source, operating with Argon gas, capable to generate a plasma beam with parameters (i.e. density and electron temperature) close to the values encountered in the ionosphere at F layer altitudes. The plasma beam (A+ ions and electrons) is accelerated into the chamber at a velocity that reproduces the relative motion between an orbiting satellite and the ionosphere (≈ 8 km/s). This feature, in particular, allows laboratory simulations of the actual compression and depletion phenomena which take place in the ram and wake regions around satellites moving through the ionosphere. The reproduced plasma environment is monitored using Langmuir Probes (LP) and Retarding Potential Analyzers (RPA). These sensors can be automatically moved within the experimental space using a sled mechanism. Such a feature allows the acquisition of the plasma parameters all around the space payload installed into the chamber for testing. The facility is currently in use to test the payloads of CSES satellite (Chinese Seismic Electromagnetic Satellite) devoted to plasma parameters and electric field measurements in a polar orbit at 500 km altitude.

Attitudes of Nursing Facilities' Staff Toward Pharmacy Students' Interaction with its Residents.

PubMed

Adkins, Donna; Gavaza, Paul; Deel, Sharon

2017-06-01

All Appalachian College of Pharmacy second-year students undertake the longitudinal geriatric early pharmacy practice experiences (EPPE) 2 course, which involves interacting with geriatric residents in two nursing facilities over two semesters. The study investigated the nursing staff's perceptions about the rotation and the pharmacy students' interaction with nursing facility residents. Cross-sectional study. Academic setting. 63 nursing facility staff. A 10-item attitude survey administered to nursing staff. Nursing staff attitude toward pharmacy students' interaction with geriatric residents during the course. Sixty-three responses were received (84% response rate). Most respondents were female (95.2%), who occasionally interacted with pharmacy students (54.8%) and had worked at the facilities for an average of 6.8 years (standard deviation [SD] = 6.7) years. Staff reported that pharmacy students practiced interacting with geriatric residents and nursing facility staff, learned about different medications taken by residents as well as their life as a nursing facility resident. In addition, the student visits improved the mood of residents and staff's understanding of medicines, among others. Staff suggested that students spend more time with their residents in the facility as well as ask more questions of staff. The nursing facility staff generally had favorable attitudes about pharmacy students' visits in their nursing facility. Nursing facility staff noted that the geriatric rotation was a great learning experience for the pharmacy students.

Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karle’s Fellowship

DTIC Science & Technology

2015-11-30

Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--15-9650 Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL... Plasma Physics Division i REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 3. DATES COVERED (From - To) Standard Form 298 (Rev. 8-98...ABSTRACT Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karle’s Fellowship Sandra (Hernandez) Hangarter Naval Research Laboratory 4555

Implosion dynamics of condensed Z-pinch at the Angara-5-1 facility

NASA Astrophysics Data System (ADS)

Aleksandrov, V. V.; Grabovski, E. V.; Gritsuk, A. N.; Volobuev, I. V.; Kazakov, E. D.; Kalinin, Yu. G.; Korolev, V. D.; Laukhin, Ya. I.; Medovshchikov, S. F.; Mitrofanov, K. N.; Oleinik, G. M.; Pimenov, V. G.; Smirnova, E. A.; Ustroev, G. I.; Frolov, I. N.

2017-08-01

The implosion dynamics of a condensed Z-pinch at load currents of up to 3.5 MA and a current rise time of 100 ns was studied experimentally at the Angara-5-1 facility. To increase the energy density, 1- to 3-mm-diameter cylinders made of a deuterated polyethylene-agar-agar mixture or microporous deuterated polyethylene with a mass density of 0.03-0.5 g/cm3 were installed in the central region of the loads. The plasma spatiotemporal characteristics were studied using the diagnostic complex of the Angara-5-1 facility, including electron-optical streak and frame imaging, time-integrated X-ray imaging, soft X-ray (SXR) measurements, and vacuum UV spectroscopy. Most information on the plasma dynamics was obtained using a ten-frame X-ray camera ( E > 100 eV) with an exposure of 4 ns. SXR pulses were recorded using photoemissive vacuum X-ray detectors. The energy characteristics of neutron emission were measured using the time-offlight method with the help of scintillation detectors arranged along and across the pinch axis. The neutron yield was measured by activation detectors. The experimental results indicate that the plasma dynamics depends weakly on the load density. As a rule, two stages of plasma implosion were observed. The formation of hot plasma spots in the initial stage of plasma expansion from the pinch axis was accompanied by short pulses of SXR and neutron emission. The neutron yield reached (0.4-3) × 1010 neutrons/shot and was almost independent of the load density due to specific features of Z-pinch dynamics.

Interactions between laser and arc plasma during laser-arc hybrid welding of magnesium alloy

NASA Astrophysics Data System (ADS)

Liu, Liming; Chen, Minghua

2011-09-01

This paper presents the results of the investigation on the interactions between laser and arc plasma during laser-arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique. By comparably analyzing the variation in plasma information (the shape, the electron temperature and density) of single tungsten inert gas (TIG) welding with the laser-arc hybrid welding, it is found that the laser affects the arc plasma through the keyhole forming on the workpiece. Depending on the welding parameters there are three kinds of interactions taking place between laser and arc plasma.

First observations of stimulated electromagnetic emission in the ionosphere modified by the spear heating facility on Spitsbergen

NASA Astrophysics Data System (ADS)

Tereshchenko, E. D.; Yurik, R. Yu.; Yeoman, T. K.; Robinson, T. R.

2008-11-01

We present the first results of observations of the stimulated electromagnetic emission (SEE) in the ionosphere modified by the Space Plasma Exploration by Active Radar (SPEAR) heating facility. Observation of the SEE is the key method of ground-based diagnostics of the ionospheric plasma disturbances due to high-power HF radiation. The presented results were obtained during the heating campaign performed at the SPEAR facility in February-March 2007. Prominent SEE special features were observed in periods in which the critical frequency of the F 2 layer was higher than the pump-wave frequency (4.45 MHz). As an example, such special features as the downshifted maximum and the broad continuum in the region of negative detunings from the pump-wave frequency are presented. Observations clearly demonstrate that the ionosphere was efficiently excited by the SPEAR heating facility despite the comparatively low pump-wave power.

Comparative study on interactions between laser and arc plasma during laser-GTA welding and laser-GMA welding

NASA Astrophysics Data System (ADS)

Chen, Minghua; Xu, Jiannan; Xin, Lijun; Zhao, Zuofu; Wu, Fufa

2016-10-01

This paper describes an investigation on differences in interactions between laser and arc plasma during laser-gas tungsten arc (LT) welding and laser-gas metal arc (LM) welding. The characteristics of LT heat source and LM heat source, such as plasma behavior, heat penetration ability and spectral information were comparably studied. Based on the plasma discharge theory, the interactions during plasma discharge were modeled and analyzed. Results show that in both LT and LM welding, coupling discharge between the laser keyhole plasma and arc happens, which strongly enhance the arc. But, the enhancing effect in LT welding is much more sensitive than that in LM welding when parameters are adjusted.

Influence of flavor oscillations on neutrino beam instabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendonça, J. T., E-mail: titomend@ist.utl.pt; Haas, F.; Bret, A.

2014-09-15

We consider the collective neutrino plasma interactions and study the electron plasma instabilities produced by a nearly mono-energetic neutrino beam in a plasma. We describe the mutual interaction between neutrino flavor oscillations and electron plasma waves. We show that the neutrino flavor oscillations are not only perturbed by electron plasmas waves but also contribute to the dispersion relation and the growth rates of neutrino beam instabilities.

Laser-plasma interaction experiments and diagnostics at NRL (Naval Research Laboratory). Memorandum report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ripin, B.H.; Grun, J.; Herbst, M.J.

Laser plasma interaction experiments have now advanced to the point where very quantitative measurements are required to elucidate the physic issues important for laser fusion and other applications. Detailed time-resolved knowledge of the plasma density, temperature, velocity gradients, spatial structure, heat flow characteristics, radiation emission, etc, are needed over tremendou ranges of plasma density and temperature. Moreover, the time scales are very short, aggrevating the difficulty of the measurements further. Nonetheless, such substantial progress has been made in diagnostic development during the past few years that we are now able to do well diagnosed experiments. In this paper the authorsmore » review recent diagnostic developments for laser-plasma interactions, outline their regimes of applicability, and show examples of their utility. In addition to diagnostics for the high densities and temperature characteristic of laser fusion physics studies, diagnostics designed to study the two-stream interactions of laser created plasma flowing through an ambient low density plasma will be described.« less

The effects of return current and target charging in short pulse high intensity laser interactions

NASA Astrophysics Data System (ADS)

Beg, Farhat

2003-10-01

Since the introduction of the technique of chirped pulse amplification (CPA), peak laser intensities have increased dramatically. It is now possible to perform laser-plasma interaction experiments at intensities approaching 1021 Wcm-2. The electrons in the field of such lasers are highly relativistic (gamma 31) and the temperature of the hot electron distribution produced in a plasma at such extreme intensities can exceed 10 MeV. Since the resulting beam current exceeds the Alfvén limit, a neutralizing return current of cold plasma electrons moving in the opposite direction is produced. Another source of return current is that due to the escape of very energetic electrons from the target, which then creates a large electrostatic potential due to charge separation. These return currents can cause significant ohmic heating. We present results from experiments performed at Rutherford Appleton Laboratory using the VULCAN laser facility (I> 5 x1019 Wcm-2). Single wire targets were used and in some shots a secondary wire or foil was placed near the target. Three main observations were made: (i) generation of a Z-pinch in the wire due to the return current, (ii) optical transition radiation at 2w and (iii) proton emission from both the primary wire target and the secondary wire or foil. The Z-pinch was observed to be m=0 unstable. The current was estimated to be about 0.8 MA using simple energy balance considerations. Intense second harmonic emission due to coherent optical transition radiation from both the primary target and secondary objects was observed and is likely due to electron bunches accelerated by the ponderomotive jxB force of the laser. The proton emission from the secondary wire or foil was likely due to field emission of electrons from the these objects in response to the large potential produced from charging of the primary target. Results of simulations to model these interactions will also be presented.

Implementation of a plasma-neutral model in NIMROD

NASA Astrophysics Data System (ADS)

Taheri, S.; Shumlak, U.; King, J. R.

2016-10-01

Interaction between plasma fluid and neutral species is of great importance in the edge region of magnetically confined fusion plasmas. The presence of neutrals can have beneficial effects such as fueling burning plasmas and quenching the disruptions in tokamaks, as well as deleterious effects like depositing high energy particles on the vessel wall. The behavior of edge plasmas in magnetically confined systems has been investigated using computational approaches that utilize the fluid description for the plasma and Monte Carlo transport for neutrals. In this research a reacting plasma-neutral model is implemented in NIMROD to study the interaction between plasma and neutral fluids. This model, developed by E. T. Meier and U. Shumlak, combines a single-fluid magnetohydrodynamic (MHD) plasma model with a gas dynamic neutral fluid model which accounts for electron-impact ionization, radiative recombination, and resonant charge exchange. Incorporating this model into NIMROD allows the study of the interaction between neutrals and plasma in a variety of plasma science problems. An accelerated plasma moving through a neutral gas background in a coaxial electrode configuration is modeled, and the results are compared with previous calculations from the HiFi code.

Titan's Variable Plasma Interaction

NASA Astrophysics Data System (ADS)

Ledvina, S. A.; Brecht, S. H.

2015-12-01

Cassini observations have found that the plasma and magnetic field conditions upstream of Titan are far more complex than they were thought to be after the Voyager encounter. Rymer et al., (2009) used the Cassini Plasma Spectrometer (CAPS) electron observations to classify the plasma conditions along Titan's orbit into 5 types (Plasma Sheet, Lobe, Mixed, Magnetosheath and Misc.). Nemeth et al., (2011) found that the CAPS ion observations could also be separated into the same plasma regions as defined by Rymer et al. Additionally the T-96 encounter found Titan in the solar wind adding a sixth classification. Understanding the effects of the variable upstream plasma conditions on Titan's plasma interaction and the evolution of Titan's ionosphere/atmosphere is one of the main objectives of the Cassini mission. To compliment the mission we perform hybrid simulations of Titan's plasma interaction to examine the effects of the incident plasma distribution function and the flow velocity. We closely examine the results on Titan's induced magnetosphere and the resulting pickup ion properties.

Weak turbulence theory for beam-plasma interaction

NASA Astrophysics Data System (ADS)

Yoon, Peter H.

2018-01-01

The kinetic theory of weak plasma turbulence, of which Ronald C. Davidson was an important early pioneer [R. C. Davidson, Methods in Nonlinear Plasma Theory, (Academic Press, New York, 1972)], is a venerable and valid theory that may be applicable to a large number of problems in both laboratory and space plasmas. This paper applies the weak turbulence theory to the problem of gentle beam-plasma interaction and Langmuir turbulence. It is shown that the beam-plasma interaction undergoes various stages of physical processes starting from linear instability, to quasilinear saturation, to mode coupling that takes place after the quasilinear stage, followed by a state of quasi-static "turbulent equilibrium." The long term quasi-equilibrium stage is eventually perturbed by binary collisional effects in order to bring the plasma to a thermodynamic equilibrium with increased entropy.

A cooler Penning trap for the TITAN mass measurement facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chowdhury, U.; Kootte, B.; Good, M.

The TITAN facility at TRIUMF makes use of highly charged ions, charge-bred in an electron beam ion trap, to carry out accurate mass measurements on radioactive isotopes. We report on our progress to develop a cooler Penning trap, CPET, which aims at reducing the energy spread of the ions to ≈ 1 eV/charge prior to injection into the mass measurement trap. In off-line mode, we can now trap electron plasmas for minutes, and we observe the damping of the m = 1 diocotron plasma mode within ≈ 2 s.

Betatron x-ray radiation in the self-modulated wakefield acceleration regime (Conference Presentation)

NASA Astrophysics Data System (ADS)

Albert, Felicie

2017-05-01

Betatron x-ray radiation, driven by electrons from laser-wakefield acceleration, has unique properties to probe high energy density (HED) plasmas and warm dense matter. Betatron radiation is produced when relativistic electrons oscillate in the plasma wake of a laser pulse. Its properties are similar to those of synchrotron radiation, with a 1000 fold shorter pulse. This presentation will focus on the experimental challenges and results related to the development of betatron radiation in the self modulated regime of laser wakefield acceleration. We observed multi keV Betatron x-rays from a self-modulated laser wakefield accelerator. The experiment was performed at the Jupiter Laser Facility, LLNL, by focusing the Titan short pulse beam (4-150 J, 1 ps) onto the edge of a Helium gas jet at electronic densities around 1019 cm-3. For the first time on this laser system, we used a long focal length optic, which produced a laser normalized potential a0 in the range 1-3. Under these conditions, electrons are accelerated by the plasma wave created in the wake of the light pulse. As a result, intense Raman satellites, which measured shifts depend on the electron plasma density, were observed on the laser spectrum transmitted through the target. Electrons with energies up to 200 MeV, as well as Betatron x-rays with critical energies around 20 keV, were measured. OSIRIS 2D PIC simulations confirm that the electrons gain energy both from the plasma wave and from their interaction with the laser field.

Controlling and monitoring the space-station plasma interaction: A baseline for performing plasma experiments and using advanced technology

NASA Technical Reports Server (NTRS)

Whipple, Elden C.; Olsen, Richard C.

1986-01-01

The size, complexity, and motion of space station through the Earth's environmental plasma means that there will be a large, complicated interaction region, involving a sheath, wake, charging of surfaces, induced electric fields, secondary emission, outgassing with ionization, etc. This interaction will necessarily be a factor in carrying out and interpreting plasma experiments and in the use of certain technologies. Attention should be given ahead of time to: (1) monitoring this interaction so that it is well described; (2) implifying the interaction by appropriate design and construction of the spacecraft and by appropriate planning of technology use; and (3) controlling the interaction by both active and passive means. Plasma emitters for modifying and controlling the spacecraft charge should be placed in several locations. Portable electrostatic shields could be deployed around noisy sections of the spacecraft in order to carry out sensitive experiments. A particle umbrella could be raised to deflect the ram ions and neutrals in order to provide a controlled environment. These interactions are briefly discussed.

Advancing Pre-college Science and Mathematics Education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Rick

With support from the US Department of Energy, Office of Science, Fusion Energy Sciences, and General Atomics, an educational and outreach program primarily for grades G6-G13 was developed using the basic science of plasma and fusion as the content foundation. The program period was 1994 - 2015 and provided many students and teachers unique experiences such as a visit to the DIII-D National Fusion Facility to tour the nation’s premiere tokamak facility or to interact with interesting and informative demonstration equipment and have the opportunity to increase their understanding of a wide range of scientific content, including states of matter,more » the electromagnetic spectrum, radiation & radioactivity, and much more. Engaging activities were developed for classroom-size audiences, many made by teachers in Build-it Day workshops. Scientist and engineer team members visited classrooms, participated in science expositions, held workshops, produced informational handouts in paper, video, online, and gaming-CD format. Participants could interact with team members from different institutions and countries and gain a wider view of the world of science and engineering educational and career possibilities. In addition, multiple science stage shows were presented to audiences of up to 700 persons in a formal theatre setting over a several day period at Science & Technology Education Partnership (STEP) Conferences. Annually repeated participation by team members in various classroom and public venue events allowed for the development of excellent interactive skills when working with students, teachers, and educational administrative staff members. We believe this program has had a positive impact in science understanding and the role of the Department of Energy in fusion research on thousands of students, teachers, and members of the general public through various interactive venues.« less

Plasma equilibrium control during slow plasma current quench with avoidance of plasma-wall interaction in JT-60U

NASA Astrophysics Data System (ADS)

Yoshino, R.; Nakamura, Y.; Neyatani, Y.

1997-08-01

In JT-60U a vertical displacement event (VDE) is observed during slow plasma current quench (Ip quench) for a vertically elongated divertor plasma with a single null. The VDE is generated by an error in the feedback control of the vertical position of the plasma current centre (ZJ). It has been perfectly avoided by improving the accuracy of the ZJ measurement in real time. Furthermore, plasma-wall interaction has been avoided successfully during slow Ip quench owing to the good performance of the plasma equilibrium control system

Status of Plasma Electron Hose Instability Studies in FACET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adli, Erik; /U. Oslo; England, Robert Joel

In the FACET plasma-wakefield acceleration experiment a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electronmore » hose instability. The FACET plasma-wakefield experiment at SLAC will study beam driven plasma wakefield acceleration. A dense 23 GeV electron beam will interact with lithium or cesium plasma, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons drives the electron hose instability, as first studied by Whittum. While Ref. [2] indicates the possibility of a large instability growth rate for typical beam and plasma parameters, other studies including have shown that several physical effects may mitigate the hosing growth rate substantially. So far there has been no quantitative benchmarking of experimentally observed hosing in previous experiments. At FACET we aim to perform such benchmarking by for example inducing a controlled z-x tilt along the beamentering the plasma, and observing the transverse behavior of the beam in the plasma as function. The long-term objective of these studies is to quantify potential limitations on future plasma wakefield accelerators due to the electron hose instability.« less

Multiphase-Multifunctional Ceramic Coatings

DTIC Science & Technology

2013-06-30

were conducted at 1200-1600° C from 10-24 h. Densification of powders in the pyrochlore-fuorite system was also performed by Spark Plasma Sintering ...capability with emphasis on improving toughness and phase stability. The primary goal was clearly accomplished by developing an instrumented air plasma ...composition. Coating compositions were synthesized by atmospheric plasma spray (APS) at CINVESTAV facilities, and dense monolithic counterparts were

Space-Time Characterization of Laser Plasma Interactions in the Warm Dense Matter Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2008-04-30

Laser plasma interaction experiments have been performed using a fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. The electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were compared with hydrodynamic simulation. First results to characterize the plasma density and temperature as a function of space and time are obtained. This work aims to generate plasmas in the warm dense matter (WDM) regime at near solid-density in anmore » ultra-fast laser target interaction process. Plasmas under these conditions can serve as targets to develop x-ray Thomson scattering as a plasma diagnostic tool, e.g., using the VUV free-electron laser (FLASH) at DESY Hamburg.« less

CSF/plasma ratios of amino acids: reference data and transports in children.

PubMed

Akiyama, Tomoyuki; Kobayashi, Katsuhiro; Higashikage, Akihito; Sato, Junko; Yoshinaga, Harumi

2014-01-01

We intended to investigate the effects of age, gender, and medications on amino acid cerebrospinal fluid (CSF)/plasma ratios in children, and to determine whether amino acid transports across the blood-CSF barrier in children differ from those in adults. Amino acid concentrations measured by ion-exchange high-performance liquid chromatography were used (CSF from 99 children, simultaneously collected plasma from 76 children). Influence of age, gender, and medications on the amino acid CSF concentrations and CSF/plasma ratios were analyzed by linear multiple regression. Interactions of amino acid transports were analyzed by correlation analysis of CSF/plasma ratios. CSF/plasma ratios of serine, valine, histidine, and arginine were higher in younger children. The glutamate CSF/plasma ratio was higher in older children. Serine, alanine, threonine, valine, and histidine CSF/plasma ratios were lower in females. Glutamine, methionine, tyrosine, and phenylalanine CSF/plasma ratios were elevated with valproate therapy. Serine, threonine, valine, leucine, and tyrosine CSF/plasma ratios were lower with clobazam therapy. The asparagine CSF/plasma ratio was elevated with pyridoxal phosphate therapy. Transports of most essential neutral amino acids interacted with each other, as did neutral amino acids with low molecular weights. Cationic amino acids interacted with each other and some essential neutral amino acids. Acidic amino acids had no interactions with other amino acids. Age, gender, and anti-epileptic drugs affect amino acid CSF/plasma ratios in children. Transport interactions between amino acids in children showed no remarkable difference from those of adults and generally followed the substrate specificities of multiple amino acid transport systems. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

TECHNOLOGY EVALUATION REPORT: RETECH'S PLASMA CENTRIFUGAL FURNACE - VOLUME I

EPA Science Inventory

A demonstration of the Retech, Inc. Plasma Centrifugal Furnace (PCF) was conducted under the Superfund Innovative Technology Evaluation (SITE) Program at the Department of Energy's (DOE's) Component Development and Integration Facility in Butte, Montana. The furnace uses heat gen...

Interaction between Paracoccidioides brasiliensis conidia and the coagulation system: involvement of fibrinogen

PubMed Central

Tamayo, Diana; Hernández, Orville; Muñoz-Cadavid, Cesar; Cano, Luz Elena; González, Angel

2013-01-01

The infectious process starts with an initial contact between pathogen and host. We have previously demonstrated that Paracoccidioides brasiliensis conidia interact with plasma proteins including fibrinogen, which is considered the major component of the coagulation system. In this study, we evaluated the in vitro capacity of P. brasiliensis conidia to aggregate with plasma proteins and compounds involved in the coagulation system. We assessed the aggregation of P. brasiliensis conidia after incubation with human serum or plasma in the presence or absence of anticoagulants, extracellular matrix (ECM) proteins, metabolic and protein inhibitors, monosaccharides and other compounds. Additionally, prothrombin and partial thromboplastin times were determined after the interaction of P. brasiliensis conidia with human plasma. ECM proteins, monosaccharides and human plasma significantly induced P. brasiliensis conidial aggregation; however, anticoagulants and metabolic and protein inhibitors diminished the aggregation process. The extrinsic coagulation pathway was not affected by the interaction between P. brasiliensis conidia and plasma proteins, while the intrinsic pathway was markedly altered. These results indicate that P. brasiliensis conidia interact with proteins involved in the coagulation system. This interaction may play an important role in the initial inflammatory response, as well as fungal disease progression caused by P. brasiliensis dissemination. PMID:23827999

NASA Wallops Flight Facility Air-Sea Interaction Research Facility

NASA Technical Reports Server (NTRS)

Long, Steven R.

1992-01-01

This publication serves as an introduction to the Air-Sea Interaction Research Facility at NASA/GSFC/Wallops Flight Facility. The purpose of this publication is to provide background information on the research facility itself, including capabilities, available instrumentation, the types of experiments already done, ongoing experiments, and future plans.

Orthos, an alarm system for the ALICE DAQ operations

NASA Astrophysics Data System (ADS)

Chapeland, Sylvain; Carena, Franco; Carena, Wisla; Chibante Barroso, Vasco; Costa, Filippo; Denes, Ervin; Divia, Roberto; Fuchs, Ulrich; Grigore, Alexandru; Simonetti, Giuseppe; Soos, Csaba; Telesca, Adriana; Vande Vyvre, Pierre; von Haller, Barthelemy

2012-12-01

ALICE (A Large Ion Collider Experiment) is the heavy-ion detector studying the physics of strongly interacting matter and the quark-gluon plasma at the CERN LHC (Large Hadron Collider). The DAQ (Data Acquisition System) facilities handle the data flow from the detectors electronics up to the mass storage. The DAQ system is based on a large farm of commodity hardware consisting of more than 600 devices (Linux PCs, storage, network switches), and controls hundreds of distributed hardware and software components interacting together. This paper presents Orthos, the alarm system used to detect, log, report, and follow-up abnormal situations on the DAQ machines at the experimental area. The main objective of this package is to integrate alarm detection and notification mechanisms with a full-featured issues tracker, in order to prioritize, assign, and fix system failures optimally. This tool relies on a database repository with a logic engine, SQL interfaces to inject or query metrics, and dynamic web pages for user interaction. We describe the system architecture, the technologies used for the implementation, and the integration with existing monitoring tools.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dong-Hwan; Hong, Suk-Ho; National Fusion Research Institute

Plasma characteristics in the far scrape-off layer region of tokamak play a crucial role in the stable plasma operation and its sustainability. Due to the huge facility, electrical diagnostic systems to measure plasma properties have extremely long cable length resulting in large stray current. To overcome this problem, a sideband harmonic method was applied to the Korea Superconducting Tokamak Advanced Research tokamak plasma. The sideband method allows the measurement of the electron temperature and the plasma density without the effect of the stray current. The measured plasma densities are compared with those from the interferometer, and the results show reliabilitymore » of the method.« less

Novel gene-by-environment interactions: APOB and NPC1L1 variants affect the relationship between dietary and total plasma cholesterol[S

PubMed Central

Kim, Daniel S.; Burt, Amber A.; Ranchalis, Jane E.; Jarvik, Ella R.; Rosenthal, Elisabeth A.; Hatsukami, Thomas S.; Furlong, Clement E.; Jarvik, Gail P.

2013-01-01

Cardiovascular disease (CVD) is the leading cause of death in developed countries. Plasma cholesterol level is a key risk factor in CVD pathogenesis. Genetic and dietary variation both influence plasma cholesterol; however, little is known about dietary interactions with genetic variants influencing the absorption and transport of dietary cholesterol. We sought to determine whether gut expressed variants predicting plasma cholesterol differentially affected the relationship between dietary and plasma cholesterol levels in 1,128 subjects (772/356 in the discovery/replication cohorts, respectively). Four single nucleotide polymorphisms (SNPs) within three genes (APOB, CETP, and NPC1L1) were significantly associated with plasma cholesterol in the discovery cohort. These were subsequently evaluated for gene-by-environment (GxE) interactions with dietary cholesterol for the prediction of plasma cholesterol, with significant findings tested for replication. Novel GxE interactions were identified and replicated for two variants: rs1042034, an APOB Ser4338Asn missense SNP and rs2072183 (in males only), a synonymous NPC1L1 SNP in linkage disequilibrium with SNPs 5′ of NPC1L1. This study identifies the presence of novel GxE and gender interactions implying that differential gut absorption is the basis for the variant associations with plasma cholesterol. These GxE interactions may account for part of the “missing heritability” not accounted for by genetic associations. PMID:23482652

Toward Direct Reaction-in-Flight Measurements

NASA Astrophysics Data System (ADS)

Wilhelmy, Jerry; Bredeweg, Todd; Fowler, Malcolm; Gooden, Matthew; Hayes, Anna; Rusev, Gencho; Caggiano, Joseph; Hatarik, Robert; Henry, Eugene; Tonchev, Anton; Yeaman, Charles; Bhike, Megha; Krishichayan, Krishi; Tornow, Werner

2016-03-01

At the National Ignition Facility (NIF) neutrons having energies greater than the equilibrium 14.1 MeV value can be produced via Reaction-in-Flight (RIF) interactions between plasma atoms and upscattered D or T ions. The yield and spectrum of these RIF produced neutrons carry information on the plasma properties as well as information on the stopping power of ions under plasma conditions. At NIF the yield of these RIF neutrons is predicted to be 4-7 orders of magnitude below the peak 14 MeV neutron yield. The current generation of neutron time of flight (nTOF) instrumentation has so far been incapable of detecting these low-yield neutrons primarily due to high photon backgrounds. To date, information on RIF neutrons has been obtained in integral activation experiments using reactions with high energy thresholds such as 169Tm(n,3n)167Tm and 209Bi(n,4n) 206Bi. Initial experiments to selectively suppress photon backgrounds have been performed at TUNL using pulsed monoenergetic neutron beams of 14.9, 18.5, 24.2, and 28.5 MeV impinging on a Bibenzyl scintillator. By placing 5 cm of Pb before the scintillator we were able to selectively suppress the photons from the flash occurring at the production target and enhance the n/_signal by ~6 times.

Low Earth orbit atomic oxygen simulation for durability evaluation of solar reflector surfaces

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.

1992-01-01

To evaluate the performance and durability of solar reflector surfaces in the atomic oxygen environment typical of low Earth orbit (LEO), one must expose the reflector surface either directly to LEO or to ground-laboratory atomic oxygen environments. Although actual LEO exposures are most desired, such opportunities are typically scarce, expensive, and of limited duration. As a result, ground-laboratory exposures must be relied upon as the most practical long-term durability evaluation technique. Plasma ashers are widely used as LEO simulation facilities by producing atomic oxygen environments for durability evaluation of potential spacecraft materials. Atomic oxygen arrival differs between ground and space exposure in that plasma asher exposure produces isotropic arrival and space solar tracking produces sweeping arrival. Differences in initial impact reaction probability occur, dependent upon the energy and species existing in these environments. Due to the variations in ground-laboratory and space atomic oxygen, quantification of in-space performance based on plasma asher testing is not straightforward. The various atomic oxygen interactions that can occur with reflector surfaces, such as undercutting in organic substrates at protective coating defect sites, ground-laboratory techniques recommended for evaluating the atomic oxygen durability of reflectors based on asher exposures, and computational techniques which make use of ground-laboratory atomic oxygen exposure to predict in-space LEO durability are addressed.

Transfer Orbit Plasma Interaction Experiment (TROPIX)

NASA Astrophysics Data System (ADS)

Hickman, Mark

Viewgraphs on the Transfer Orbit Plasma Interaction Experiment (TROPIX) are presented. Objectives of this research are (1) to map the charged particles in Earth's magnetosphere from LEO to GEO at high inclinations; (2) to measure plasma current collection and resulting shifts in vehicle electrical potential from LEO to GEO across range of orbital inclinations; (3) to study spacecraft interaction with plasma environment using solar electric propulsion (SEP) thrusters as plasma contactors; (4) to measure array degradation over mission duration; (5) to evaluate the potential of various microelectronics, spacecraft components, and instruments for future space missions; and (6) to demonstrate SEP technology applied to a flight vehicle. An overview of TROPIX is presented.

A Huygens immersed-finite-element particle-in-cell method for modeling plasma-surface interactions with moving interface

NASA Astrophysics Data System (ADS)

Cao, Huijun; Cao, Yong; Chu, Yuchuan; He, Xiaoming; Lin, Tao

2018-06-01

Surface evolution is an unavoidable issue in engineering plasma applications. In this article an iterative method for modeling plasma-surface interactions with moving interface is proposed and validated. In this method, the plasma dynamics is simulated by an immersed finite element particle-in-cell (IFE-PIC) method, and the surface evolution is modeled by the Huygens wavelet method which is coupled with the iteration of the IFE-PIC method. Numerical experiments, including prototypical engineering applications, such as the erosion of Hall thruster channel wall, are presented to demonstrate features of this Huygens IFE-PIC method for simulating the dynamic plasma-surface interactions.

Radiation Production by Charged Particle Beams Ejected from a Plasma Focus.

DTIC Science & Technology

1981-02-01

The scope of this investigation concerns the development of a pulsed radiation source using the charged particle beam ejected from a plasma focus device...satellite components for radiation hardening and survivability. The plasma focus is operated in a modified geometry such that electron bursts which...a radiation facility. The plasma focus , identified as the Mark IV, is nominally rated at 34 kJ with a capacitance of 168 micro F at 20 kV. The

Interactions of vitamins A, D3, E, and K in the diet of broiler chicks.

PubMed

Abawi, F G; Sullivan, T W

1989-11-01

A total of 3,888 broiler chicks (Vantress x Arbor Acre) were used in a study involving 81 dietary treatments to determine the interactions among vitamins A, D3, E, and K in broiler chicks. Three levels of each fat-soluble vitamin representing deficient, optimum, and excessive amounts were included. Significant observations were: effect of vitamin A levels on feed efficiency (P less than .01), plasma vitamin A (P less than .01), and plasma vitamin E (P less than .01); effect of vitamin D levels on body weight gain (P less than .01) and mortality (P less than .05); effect of vitamin E levels on plasma vitamin A (P less than .01); effect of vitamin A x vitamin D interaction on body weight gain (P less than .02) and plasma vitamin E (P less than .05); effect of vitamin A x vitamin E interaction on mortality (P less than .01), plasma vitamin A (P less than .03), and plasma vitamin E (P less than .01); effect of vitamin D x vitamin K interaction on feed efficiency (P less than .05); effect of vitamin A x vitamin D x vitamin E interaction on plasma vitamin E concentration (P less than .01); effect of vitamin A x vitamin E x vitamin K interaction on mortality (P less than .05). The results of this study suggest that higher supplemental levels of vitamins D and K would improve performance of poultry occasionally being fed high supplemental levels of vitamins A and E.

The design of the optical Thomson scattering diagnostic for the National Ignition Facility [The preliminary design of the optical Thomson scattering diagnostic for the National Ignition Facility

DOE PAGES

Datte, P. S.; Ross, J. S.; Froula, D. H.; ...

2016-09-21

Here, the National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community’s understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0-210 nm) will be used to optimize the scatteredmore » signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3. We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.« less

The design of the optical Thomson scattering diagnostic for the National Ignition Facility [The preliminary design of the optical Thomson scattering diagnostic for the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datte, P. S.; Ross, J. S.; Froula, D. H.

Here, the National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community’s understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0-210 nm) will be used to optimize the scatteredmore » signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3. We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.« less

Generating Long Scale-Length Plasma Jets Embedded in a Uniform, Multi-Tesla Magnetic-Field

NASA Astrophysics Data System (ADS)

Manuel, Mario; Kuranz, Carolyn; Rasmus, Alex; Klein, Sallee; Fein, Jeff; Belancourt, Patrick; Drake, R. P.; Pollock, Brad; Hazi, Andrew; Park, Jaebum; Williams, Jackson; Chen, Hui

2013-10-01

Collimated plasma jets emerge in many classes of astrophysical objects and are of great interest to explore in the laboratory. In many cases, these astrophysical jets exist within a background magnetic field where the magnetic pressure approaches the plasma pressure. Recent experiments performed at the Jupiter Laser Facility utilized a custom-designed solenoid to generate the multi-tesla fields necessary to achieve proper magnetization of the plasma. Time-gated interferometry, Schlieren imaging, and proton radiography were used to characterize jet evolution and collimation under varying degrees of magnetization. Experimental results will be presented and discussed. This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840, by the National Laser User Facility Program, grant number DE-NA0000850, by the Predictive Sciences Academic Alliances Program in NNSA-ASC, grant number DEFC52-08NA28616, and by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060.

A Multi-ring Ionospheric Plasma Probe

NASA Technical Reports Server (NTRS)

Sheldon, J. W.

1972-01-01

An ionospheric plasma probe was constructed which consists of a long cylinder with the end facing the flow closed by an end plate made up of multiple annular rings and a center disk. A theoretical argument is given which yields the plasma potential and electron temperature in terms of known plasma parameters and the currents to the various rings of the end plate. This probe was successfully operated in an ionospheric flow simulation facility and the resulting plasma potential is in excellent agreement with the traditional Langmuir analysis (1.22 volts).

A self-consistent view on plasma-neutral interaction near a wall: plasma acceleration by momentum removal and heating by cold walls

NASA Astrophysics Data System (ADS)

van Rooij, Gerard; den Harder, Niek; Minea, Teofil; Shumack, Amy; de Blank, H.; Plasma Physics Team

2014-10-01

In plasma physics, material walls are generally regarded as perfect sinks for charged particles and their energy. A special case arises when the wall efficiently reflects the neutralized plasma particles (with a significant portion of their kinetic energy) and at the same time the upstream plasma is of sufficiently high density to yield strong neutral-ion coupling (i.e. reflected energy and momentum will not escape from the plasma). Under these conditions, plasma-surface interaction will feedback to the upstream plasma and a self-consistent view on the coupling between plasma and neutrals is required for correct prediction of plasma conditions and plasma-surface interaction. Here, an analytical and numerical study of the fluid equations is combined with experiments (in hydrogen and argon) to construct such a self-consistent view. It shows how plasma momentum removal builds up upstream pressure and causes plasma acceleration towards the wall. It also shows how energy reflection causes plasma heating, which recycles part of the reflected power to the wall and induces additional flow acceleration due to local sound speed increase. The findings are relevant as generic textbook example and are at play in the boundary plasma of fusion devices.

Experimental Investigation of the Interaction of Electrothermal Plasmas with Solid Propellants

DTIC Science & Technology

2007-09-14

formation increases propellant burning rate (Koleczko, et al . 2001). The experiments described here were designed to create time and spatially resolved...Pesce-Rodriguez 2004, Koleczko, et al . 2001). Most tests involving plasma propellant interactions involve higher plasma energies than the 3.1 kJ of...product that scatters light. The large jump in pressurization seen in closed bomb plasma ignition tests (Lieb, et al . 2001) during the plasma discharge

Experimental investigation of the effect of insulator sleeve length on the time to pinch and multipinch formation in the plasma focus facility

NASA Astrophysics Data System (ADS)

Momenei, M.; Khodabakhshei, Z.; Panahi, N.; Mohammadi, M. A.

2017-03-01

The length of insulator sleeve is varied to investigate its effect on the pinch formation in the plasma focus facility. In this paper, the effect of insulator length on the time to pinch at various pressures and working voltages in the 1.15 kJ Mather type plasma focus is investigated. The results show that with 4.5 cm insulator length the time to pinch at all pressures is minimum. Other results also confirm that with increasing of pressure the time to pinch is increased. Moreover, with increasing working voltage the time to pinch is decreased. Pictures, captured using a digital single lens reflex (DSLR) Canon EOS 7D system, show that multipinch phenomenon is formed.

Neutron generation from Z-pinches

NASA Astrophysics Data System (ADS)

Vikhrev, V. V.; Korolev, V. D.

2007-05-01

Recent advances in both experimental and theoretical studies on neutron generation in various Z-pinch facilities are reviewed. The main methods for enhancing neutron emission from the Z-pinch plasma are described, and the problems of igniting a thermonuclear burn wave in this plasma are discussed.

Strongly-Interacting Fermi Gases in Reduced Dimensions

DTIC Science & Technology

2009-05-29

effective theories of the strong interactions), astrophysics (compact stellar objects), the physics of quark -gluon plasmas (elliptic flow), and most...strong interactions: Superconductors, neutron stars and quark -gluon plasmas on a desktop," Seminar on Modern Optics and Spectroscopy, M. I. T...interface of quark -gluon plasma physics and cold-atom physics," (Trento, Italy, March 19-23, 2007). Talk given by Andrey Turlapov. 17) J. E. Thomas

Laser driven plasmas based incoherent x-ray sources at PALS and ELI Beamlines (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kozlová, Michaela

2017-05-01

We will present data on a various X-ray production schemes from laser driven plasmas at the PALS Research Center and discuss the plan for the ELI Beamlines project. One of the approaches, how to generate ultrashort pulses of incoherent X-ray radiation, is based on interaction of femtosecond laser pulses with solid or liquid targets. So-called K-alpha source depending on used targets emits in hard X-ray region from micrometric source size. The source exhibits sufficient spatial coherence to observe phase contrast. Detailed characterization of various sources including the x-ray spectrum and the x-ray average yield along with phase contrast images of test objects will be presented. Other method, known as laser wakefield electron acceleration (LWFA), can produce up to GeV electron beams emitting radiation in collimated beam with a femtosecnond pulse duration. This approach was theoretically and experimentally examined at the PALS Center. The parameters of the PALS Ti:S laser interaction were studied by extensive particle-in-cell simulations with radiation post-processors in order to evaluate the capabilities of our system in this field. The extensions of those methods at the ELI Beamlines facility will enable to generate either higher X-ray energies or higher repetition rate. The architecture of such sources and their considered applications will be proposed.

New Frontier Science Campaign on DIII-D launched in 2017

NASA Astrophysics Data System (ADS)

Koepke, M.; Buttery, R.; Carter, T.; Egedal, J.; Forest, C.; Fox, W.; Ji, H.; Howes, G.; Piovesan, P.; Sarff, J.; Skiff, F.; Spong, D.; DIII-D FSE Collaboration Collaboration

2017-10-01

The DIII-D Frontier Science Experiments initiative explores the potential to use the DIII-D tokamak facility to investigate questions of value beyond the usual fusion-energy science mission of DIII-D. The campaign is unique within DOE-SC-FES because the DIII-D tokamak supplied a multi-day-shot platform for non-fusion-energy-motivated research for the first time. All selected FSE campaign projects competed on the basis of potential intellectual impact and on the degree to which the ability to achieve success as a transformational advance relied on the capabilities of DIII-D. The motivation of the following FSE projects, as well as the selection process, will be summarized (1) Self-organization of Unstable Flux Ropes: Universal Structures in Space/Astrophysical Plasmas (2) Impact of Magnetic Perturbations on Turbulence: Zonal Flow Interactions and Saturation (3) Interaction of Alfvén/whistler fluctuations and Runaway Electrons (4) Self-consistent chaos in magnetic field dynamics These basic-plasma experiments, conducted in collaboration with the DIII-D team, were carried out during 5 shot days in FY2017. Additional days are earmarked in FY2018. Future studies with additional FSE-community members are envisioned. Opportunities exist to piggy back with DIII-D research A proper solicitation and peer review would be appropriate going forward if this activity on DIII-D continues Funding from U.S. DOE is gratefully acknowledged.

Surface voltage gradient role in high voltage solar array-plasma interaction: Center Director's discretionary fund

NASA Technical Reports Server (NTRS)

Carruth, M. R., Jr.

1985-01-01

A large amount of experimental and analytical effort has been directed toward understanding the plasma sheath growth and discharge phenomena which lead to high voltage solar array-space plasma interactions. An important question which has not been addressed is how the surface voltage gradient on such an array may affect these interactions. The results of this study indicate that under certain conditions, the voltage gradient should be taken into account when evaluating the effect on a solar array operating in a plasma environment.

Arecibo - HF experiments in the E_region

NASA Astrophysics Data System (ADS)

Nossa, E.; Jain, K.; Sulzer, M. P.; Perillat, P.

2017-12-01

The new Arecibo Observatory - HF facility started operations in 2015. The HF facility is fully operational, acquiring consecutive days of data without unwanted interruptions. It has a maximum transmitted power of 600kW, with center frequencies at 5.125 MHz and 8.175 MHz. The 8.175 (5.125) MHz band frequency has a gain of 25.5 (22) dB and HPBW of 8.5 (13) degrees. The effects of the HF experiments in the ionosphere are being observed with the Arecibo incoherent scatter radar (ISR). The ISR has two beams that simultaneously could sense the modified region and the region outside of the affected volume. The ISR has height resolution of 300 m. and allows to observe from altitudes 95 km to the topside ionosphere. Observation of the E-region - HF experiments are sparse but possible at Arecibo. High ionization at a height 100 km are needed to modify the region artificially. This paper presents examples of E-region enhanced plasma lines (See Figure). Diagnostic of the layers is made using the ISR to estimate electron density, temperatures, ion drifts, among others. The data shows exceptional modifications of the ionosphere that range from creating artificial cavities and layers, induced irregularities, substantial variations in temperature profiles to enhanced ion and plasma densities.Previously, the HF experiments were performed to study specific effects in a narrow region. However, the extent of the data collected with the ISR during 2017 is revealing new features and different kind of forces that artificially modify extended regions of the ionosphere. This paper exhibits examples where the interaction between the E and F-region when HF experiments are evident. A theory of a correlation between the two layers due to different conductivities is explored to illustrate how the enhancement of irregularities is produced and maintained over time. Examples of strong artificially induced irregularities formed at F-region heights when Sporadic E-layer is present are shown to support the theory.The Figure shows an enhanced plasma line for the diurnal E-region. For this HF experiment, the plasma density increased from 3.6 MHz to 5.1MHz (which corresponds to the HF frequency). The vertical lines observed in the Figure are artifacts from the data, as well as the fake enhanced plasma lines at frequencies different than the HF frequency.

Plasma-surface interaction in the context of ITER.

PubMed

Kleyn, A W; Lopes Cardozo, N J; Samm, U

2006-04-21

The decreasing availability of energy and concern about climate change necessitate the development of novel sustainable energy sources. Fusion energy is such a source. Although it will take several decades to develop it into routinely operated power sources, the ultimate potential of fusion energy is very high and badly needed. A major step forward in the development of fusion energy is the decision to construct the experimental test reactor ITER. ITER will stimulate research in many areas of science. This article serves as an introduction to some of those areas. In particular, we discuss research opportunities in the context of plasma-surface interactions. The fusion plasma, with a typical temperature of 10 keV, has to be brought into contact with a physical wall in order to remove the helium produced and drain the excess energy in the fusion plasma. The fusion plasma is far too hot to be brought into direct contact with a physical wall. It would degrade the wall and the debris from the wall would extinguish the plasma. Therefore, schemes are developed to cool down the plasma locally before it impacts on a physical surface. The resulting plasma-surface interaction in ITER is facing several challenges including surface erosion, material redeposition and tritium retention. In this article we introduce how the plasma-surface interaction relevant for ITER can be studied in small scale experiments. The various requirements for such experiments are introduced and examples of present and future experiments will be given. The emphasis in this article will be on the experimental studies of plasma-surface interactions.

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Alfred Y.

1999-09-20

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from themore » self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO{sub 2} through the use of ion cyclotron resonant heating.« less

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

NASA Astrophysics Data System (ADS)

Wong, Alfred Y.

1999-09-01

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.

Production and Study of High-Beta Plasma Confined by a Superconducting Dipole Magnet

NASA Astrophysics Data System (ADS)

Garnier, Darren

2005-10-01

The Levitated Dipole Experiment (LDX)http://psfcwww2.psfc.mit.edu/ldx/ is a new research facility that is exploring the confinement and stability of plasma created within the dipole field produced by a strong superconducting magnet. Unlike other configurations in which stability depends on curvature and magnetic shear, MHD stability of a dipole derives from plasma compressibility. Theoretically, the dipole magnetic geometry can stabilize a centrally-peaked plasma pressure that exceeds the local magnetic pressure (β> 1), and the absence of magnetic shear allows particle and energy confinement to decouple. In this presentation, the first experiments using the LDX facility are reported. Long-pulse, quasi-steady state microwave discharges lasting up to 12 seconds have been produced that are consistent with equilibria having peak beta values of 10%. Detailed measurements have been made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. In these initial experiments, the high-field superconducting floating coil was supported by three thin supports and later the coil will be magnetically levitated. The plasma was created by multi- frequency electron cyclotron resonance heating at 2.45 and 6.4 GHz, and a population of energetic electrons, with mean energies above 50 keV, dominated the plasma pressure. Creation of high-pressure, high-beta plasma is only possible when intense hot electron interchange instabilities are stabilized sufficiently by a high background plasma density. A dramatic transition from a low-density, low-beta regime to a more quiescent, high-beta regime is observed when the plasma-fueling rate and confinement times are sufficiently long. External shaping coils are seen to modify the outer plasma boundary and affect the transition.

Photometric study of single-shot energy-dispersive x-ray diffraction at a laser plasma facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoidn, O. R.; Seidler, G. T., E-mail: seidler@uw.edu

The low repetition rates and possible shot-to-shot variations in laser-plasma studies place a high value on single-shot diagnostics. For example, white-beam scattering methods based on broadband backlighter x-ray sources are used to determine changes in the structure of laser-shocked crystalline materials by the evolution of coincidences of reciprocal lattice vectors and kinematically allowed momentum transfers. Here, we demonstrate that white-beam techniques can be extended to strongly disordered dense plasma and warm dense matter systems where reciprocal space is only weakly structured and spectroscopic detection is consequently needed to determine the static structure factor and thus, the ion-ion radial distribution function.more » Specifically, we report a photometric study of energy-dispersive x-ray diffraction (ED-XRD) for structural measurement of high energy density systems at large-scale laser facilities such as OMEGA and the National Ignition Facility. We find that structural information can be obtained in single-shot ED-XRD experiments using established backlighter and spectrometer technologies.« less

The design of the optical Thomson scattering diagnostic for the National Ignition Facility.

PubMed

Datte, P S; Ross, J S; Froula, D H; Daub, K D; Galbraith, J; Glenzer, S; Hatch, B; Katz, J; Kilkenny, J; Landen, O; Manha, D; Manuel, A M; Molander, W; Montgomery, D; Moody, J; Swadling, G F; Weaver, J

2016-11-01

The National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community's understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0 -210 nm) will be used to optimize the scattered signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3 . We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.

FLARE: A New User Facility for Studies of Multiple-Scale Physics of Magnetic Reconnection and Related Phenomena Through in-situ Measurements

NASA Astrophysics Data System (ADS)

Ji, Hantao; Bhattacharjee, A.; Goodman, A.; Prager, S.; Daughton, W.; Cutler, R.; Fox, W.; Hoffmann, F.; Kalish, M.; Kozub, T.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Sloboda, P.; Yamada, M.; Yoo, J.; Bale, S. D.; Carter, T.; Dorfman, S.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.

2017-10-01

The FLARE device (Facility for Laboratory Reconnection Experiments; flare.pppl.gov) is a new laboratory experiment under construction at Princeton for the studies of magnetic reconnection in the multiple X-line regimes directly relevant to space, solar, astrophysical, and fusion plasmas, as guided by a reconnection phase diagram. The whole device have been assembled with first plasmas expected in the fall of 2017. The main diagnostics is an extensive set of magnetic probe arrays, currently under construction, to cover multiple scales from local electron scales ( 2 mm), to intermediate ion scales ( 10 cm), and global MHD scales ( 1 m), simultaneously providing in-situ measurements over all these relevant scales. The planned procedures and example topics as a user facility will be discussed.

Inertial fusion program and national laser users facility program

NASA Astrophysics Data System (ADS)

1995-01-01

This is the 1994 annual report for the University of Rochester, Laboratory for Laser Energetics. The report is presented as a series of research type reports. The titles emphasize the breadth of work carried out. They are: stability analysis of unsteady ablation fronts; characterization of laser-produced plasma density profiles using grid image refractometry; transport and sound waves in plasmas with light and heavy ions; three-halves-harmonic radiation from long-scale-length plasmas revisited; OMEGA upgrade status report; target imaging and backlighting diagnosis; effect of electron collisions on ion-acoustic waves and heat flow; particle-in-cell code simulations of the interaction of gaussian ultrashort laser pulses with targets of varying initial scale lengths; characterization of thick cryogenic fuel layers: compensation for the lens effect using convergent beam interferometry; compact, multijoule-output, Nd:Glass, large-aperture ring amplifier; atomic force microscopy observation of water-induced morphological changes in Y2O3 monolayer coatings; observation of longitudinal acceleration of electrons born in a high-intensity laser focus; spatial intensity nonuniformities of an OMEGA beam due to nonlinear beam propagation; calculated X-ray backlighting images of mixed imploded targets; evaluation of cosmic rays for use in the monitoring of the MEDUSA scintillator-photomultiplier diagnostic array; highly efficient second-harmonic generation of ultra-intense Nd:Glass laser pulses multiple cutoff wave numbers of the ablative Rayleigh-Taylor instability; ultrafast, all-silicon light modulator; angular dependence of the stimulated Brillouin scattering in homogeneous plasma; and femtosecond excited-state dynamics of a conjugated ladder polymer.

Platelet activation and aggregation by the opportunistic pathogen Cutibacterium (Propionibacterium) acnes

PubMed Central

Petersson, Frida; Kilsgård, Ola; Shannon, Oonagh

2018-01-01

Cutibacterium (Propionibacterium) acnes, considered a part of the skin microbiota, is one of the most commonly isolated anaerobic bacteria from medical implants in contact with plasma. However, the precise interaction of C. acnes with blood cells and plasma proteins has not been fully elucidated. Herein, we have investigated the molecular interaction of C. acnes with platelets and plasma proteins. We report that the ability of C. acnes to aggregate platelets is dependent on phylotype, with a significantly lower ability amongst type IB isolates, and the interaction of specific donor-dependent plasma proteins (or concentrations thereof) with C. acnes. Pretreatment of C. acnes with plasma reduces the lag time before aggregation demonstrating that pre-deposition of plasma proteins on C. acnes is an important step in platelet aggregation. Using mass spectrometry we identified several plasma proteins deposited on C. acnes, including IgG, fibrinogen and complement factors. Inhibition of IgG, fibrinogen or complement decreased C. acnes-mediated platelet aggregation, demonstrating the importance of these plasma proteins for aggregation. The interaction of C. acnes and platelets was visualized using fluorescence microscopy, verifying the presence of IgG and fibrinogen as components of the aggregates, and co-localization of C. acnes and platelets in the aggregates. Here, we have demonstrated the ability of C. acnes to activate and aggregate platelets in a bacterium and donor-specific fashion, as well as added mechanistic insights into this interaction. PMID:29385206

Platelet activation and aggregation by the opportunistic pathogen Cutibacterium (Propionibacterium) acnes.

PubMed

Petersson, Frida; Kilsgård, Ola; Shannon, Oonagh; Lood, Rolf

2018-01-01

Cutibacterium (Propionibacterium) acnes, considered a part of the skin microbiota, is one of the most commonly isolated anaerobic bacteria from medical implants in contact with plasma. However, the precise interaction of C. acnes with blood cells and plasma proteins has not been fully elucidated. Herein, we have investigated the molecular interaction of C. acnes with platelets and plasma proteins. We report that the ability of C. acnes to aggregate platelets is dependent on phylotype, with a significantly lower ability amongst type IB isolates, and the interaction of specific donor-dependent plasma proteins (or concentrations thereof) with C. acnes. Pretreatment of C. acnes with plasma reduces the lag time before aggregation demonstrating that pre-deposition of plasma proteins on C. acnes is an important step in platelet aggregation. Using mass spectrometry we identified several plasma proteins deposited on C. acnes, including IgG, fibrinogen and complement factors. Inhibition of IgG, fibrinogen or complement decreased C. acnes-mediated platelet aggregation, demonstrating the importance of these plasma proteins for aggregation. The interaction of C. acnes and platelets was visualized using fluorescence microscopy, verifying the presence of IgG and fibrinogen as components of the aggregates, and co-localization of C. acnes and platelets in the aggregates. Here, we have demonstrated the ability of C. acnes to activate and aggregate platelets in a bacterium and donor-specific fashion, as well as added mechanistic insights into this interaction.

Shuttle-era experiments in the area of plasma flow interactions with bodies in space

NASA Technical Reports Server (NTRS)

Samir, U.; Stone, N. H.

1980-01-01

A new experimental approach is discussed that can be adopted for studies in the area of plasma flow interactions with bodies in space. The potential use of the Space Shuttle/Orbiter as a near-earth plasma laboratory for studies in space plasma physics and particularly in solar system plasmas is discussed. This new experimental approach holds great promise for studies in the supersonic and sub-Alfvenic flow regime which has applications to the motion of natural satellites around their mother planets in the solar-system (e.g., the satellite Io around the planet Jupiter). A well conceived experimental and theoretical program can lead to a better physical understanding regarding the validity and range of applicability of using gasdynamic, kinetic, and fluid approaches in describing collisionless plasma flow interactions with bodies in a variety of flow regimes. In addition to the above scientific aspects of the program, significant technological advances can be achieved regarding the interaction of space probes in planetary atmospheres/ionospheres and the reliability of using various plasma diagnostic devices on board spacecraft and large space platforms.

HISCAT: A proposed new scatter facility in Northern Scandinavia

NASA Technical Reports Server (NTRS)

Bostrom, R.; Thide, B.

1986-01-01

It is proposed that a new versatile ionospheric and atmospheric scatter radar be constructed in northern Scandavia through a multinational collaborative effort. The new facility tentatively named HISCAT (High frequency, High power, High latitude, Heating and Ionospheric Scatter facility), should be used for scientific investigations of: the physics of the neutral (middle) atmosphere; fundamental plasma phenomena, natural or artificially induced in the ionosphere; electrodynamic conditions at high altitudes above the auroral region and in the polar cap ionosphere; plasma waves in the solar atmosphere. The system should thus be able to operate as a mesosphere-stratosphere-troposphere (MST) radar, a so-called ionospheric modification facility, incoherent-scatter radar, coherent-scatter radar, and solar radar. Basically, the new facility should be a device that can operate simultaneously on several frequencies in the frequency range 5 to 50 MHz not covered by other instruments. It should comprise: powerful transmitters, capable of delivering a total average power of several megawatts; an advanced phased antenna array of high gain forming one or two steerable and well collimated beams; and an advanced data collection and analysis system.

Interaction between La(III) and proteins on the plasma membrane of horseradish

NASA Astrophysics Data System (ADS)

Yang, Guang-Mei; Chu, Yun-Xia; Lv, Xiao-Fen; Zhou, Qing; Huang, Xiao-Hua

2012-06-01

Lanthanum (La) is an important rare earth element in the ecological environment of plant. The proteins on the plasma membrane control the transport of molecules into and out of cell. It is very important to investigate the effect of La(III) on the proteins on the plasma membrane in the plant cell. In the present work, the interaction between La(III) and proteins on the plasma membrane of horseradish was investigated using optimization of the fluorescence microscopy and fluorescence spectroscopy. It is found that the fluorescence of the complex system of protoplasts and 1-aniline Kenai-8-sulfonic acid in horseradish treated with the low concentration of La(III) is increased compared with that of the control horseradish. The opposite effect is observed in horseradish treated with the high concentration of La(III). These results indicated that the low concentration of La(III) can interact with the proteins on the plasma membrane of horseradish, causing the improvement in the structure of proteins on the plasma membrane. The high concentration of La(III) can also interact with the proteins on the plasma membrane of horseradish, leading to the destruction of the structure of proteins on the plasma membrane. We demonstrate that the proteins on the plasma membrane are the targets of La(III) action on plant cell.

Calculating the radiation characteristics of accelerated electrons in laser-plasma interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, X. F.; Graduate School of Engineering, Utsunomiya University, 7-1-2 Yohtoh, Utsunomiya 321-8585; Yu, Q.

2016-03-15

In this paper, we studied the characteristics of radiation emitted by electrons accelerated in a laser–plasma interaction by using the Lienard–Wiechert field. In the interaction of a laser pulse with a underdense plasma, electrons are accelerated by two mechanisms: direct laser acceleration (DLA) and laser wakefield acceleration (LWFA). At the beginning of the process, the DLA electrons emit most of the radiation, and the DLA electrons emit a much higher peak photon energy than the LWFA electrons. As the laser–plasma interaction progresses, the LWFA electrons become the major radiation emitter; however, even at this stage, the contribution from DLA electronsmore » is significant, especially to the peak photon energy.« less

Interaction of N-vortex structures in a continuum, including atmosphere, hydrosphere and plasma

NASA Astrophysics Data System (ADS)

Belashov, Vasily Yu.

2017-10-01

The results of analysis and numerical simulation of evolution and interaction of the N-vortex structures of various configuration and different vorticities in the continuum including atmosphere, hydrosphere and plasma are presented. It is found that in dependence on initial conditions the regimes of weak interaction with quasi-stationary evolution and active interaction with the "phase intermixing", when the evolution can lead to formation of complex forms of vorticity regions, are realized in the N-vortex systems. For the 2-vortex interaction the generalized critical parameter determining qualitative character of interaction of vortices is introduced. It is shown that for given initial conditions its value divides modes of active interaction and quasi-stationary evolution. The results of simulation of evolution and interaction of the two-dimensional and three-dimensional vortex structures, including such phenomena as dynamics of the atmospheric synoptic vortices of cyclonic types and tornado, hydrodynamic 4-vortex interaction and also interaction in the systems of a type of "hydrodynamic vortex - dust particles" are presented. The applications of undertaken approach to the problems of such plasma systems as streams of charged particles in a uniform magnetic field B and plasma clouds in the ionosphere are considered. It is shown that the results obtained have obvious applications in studies of the dynamics of the vortex structures dynamics in atmosphere, hydrosphere and plasma.

Research briefing on contemporary problems in plasma science

NASA Technical Reports Server (NTRS)

1991-01-01

An overview is presented of the broad perspective of all plasma science. Detailed discussions are given of scientific opportunities in various subdisciplines of plasma science. The first subdiscipline to be discussed is the area where the contemporary applications of plasma science are the most widespread, low temperature plasma science. Opportunities for new research and technology development that have emerged as byproducts of research in magnetic and inertial fusion are then highlighted. Then follows a discussion of new opportunities in ultrafast plasma science opened up by recent developments in laser and particle beam technology. Next, research that uses smaller scale facilities is discussed, first discussing non-neutral plasmas, and then the area of basic plasma experiments. Discussions of analytic theory and computational plasma physics and of space and astrophysical plasma physics are then presented.

Review of biased solar arraay. Plasma interaction studies

NASA Technical Reports Server (NTRS)

Stevens, N. J.

1981-01-01

The Solar Electric Propulsion System (SEPS) is proposed for a variety of space missions. Power for operating SEPS is obtained from large solar array wings capable of generating tens of kilowatts of power. To minimize resistive losses in the solar array bus lines, the array is designed to operate at voltages up to 400 volts. This use of high voltage can increase interactions between the biased solar cell interconnects and plasma environments. With thrusters operating, the system ground is maintained at space plasma potential which exposes large areas of the arrays at the operating voltages. This can increase interactions with both the natural and enhanced charged particle environments. Available data on interactions between biased solar array surfaces and plasma environments are summarized. The apparent relationship between collection phenomena and solar cell size and effects of array size on interactions are discussed. The impact of these interactions on SEPS performance is presented.

Nonlinear interactions between electromagnetic waves and electron plasma oscillations in quantum plasmas.

PubMed

Shukla, P K; Eliasson, B

2007-08-31

We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.

Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2006-09-25

Laser plasma interaction experiments have been perform performed using an fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. Electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were cautiously compared with relevant 1D numerical simulation. Finally these results provide a first experience of searching for the time-space position of the so-called warm dense plasma in an ultra fast laser target interaction process. These experiments aim to prepare nearmore » solid-density plasmas for Thomson scattering experiments using the short wavelength free-electron laser FLASH, DESY Hamburg.« less

Method and system for nanoscale plasma processing of objects

DOEpatents

Oehrlein, Gottlieb S [Clarksville, MD; Hua, Xuefeng [Hyattsville, MD; Stolz, Christian [Baden-Wuerttemberg, DE

2008-12-30

A plasma processing system includes a source of plasma, a substrate and a shutter positioned in close proximity to the substrate. The substrate/shutter relative disposition is changed for precise control of substrate/plasma interaction. This way, the substrate interacts only with a fully established, stable plasma for short times required for nanoscale processing of materials. The shutter includes an opening of a predetermined width, and preferably is patterned to form an array of slits with dimensions that are smaller than the Debye screening length. This enables control of the substrate/plasma interaction time while avoiding the ion bombardment of the substrate in an undesirable fashion. The relative disposition between the shutter and the substrate can be made either by moving the shutter or by moving the substrate.

Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

ScienceCinema

Seryi, Andrei

2017-12-22

Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

Low-threshold parametric excitation of the upper hybrid wave in experiments on electron-cyclotron resonance heating by an ordinary wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sysoeva, E. V., E-mail: tinlit@yandex.ru; Gusakov, E. Z.; Simonchik, L. V.

2016-07-15

The possibility of the low-threshold decay of an ordinary wave into an upper hybrid wave localized in a plasma column (or in an axisymmetric plasma filament) and a low-frequency wave is analyzed. It is shown that the threshold for such a decay, accompanied by the excitation of an ion-acoustic wave, can easily be overcome for plasma parameters typical of model experiments on the Granit linear plasma facility.

Collaborative Research. Fundamental Science of Low Temperature Plasma-Biological Material Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graves, David Barry; Oehrlein, Gottlieb

2014-09-01

Low temperature plasma (LTP) treatment of biological tissue is a promising path toward sterilization of bacteria due to its versatility and ability to operate under well-controlled and relatively mild conditions. The present collaborative research of an interdisciplinary team of investigators at University of Maryland, College Park (UMD), and University of California, Berkeley (UCB) focused on establishing our knowledge based with regard to low temperature plasma-induced chemical modifications in biomolecules that result in inactivation due to various plasma species, including ions, reactive radicals, and UV/VUV photons. The overall goals of the project were to identify and quantify the mechanisms by whichmore » low and atmospheric pressure plasma deactivates endotoxic biomolecules. Additionally, we wanted to understand the mechanism by which atmospheric pressure plasmas (APP) modify surfaces and how these modifications depend on the interaction of APP with the environment. Various low pressure plasma sources, a vacuum beam system and several atmospheric pressure plasma sources were used to accomplish this. In our work we elucidated for the first time the role of ions, VUV photons and radicals in biological deactivation of representative biomolecules, both in a UHV beam system and an inductively coupled, low pressure plasma system, and established the associated atomistic biomolecule changes. While we showed that both ions and VUV photons can be very efficient in deactivation of biomolecules, significant etching and/or deep modification (~200 nm) accompanied these biological effects. One of the most important findings in this work is the significant radical-induced deactivation and surface modification can occur with minimal etching. However, if radical fluxes and corresponding etch rates are relatively high, for example at atmospheric pressure, endotoxic biomolecule film inactivation may require near-complete removal of the film. These findings motivated further work at atmospheric pressure using several types of low temperature plasma sources, for which radical induced interactions generally dominate due to short mean free paths of ions and VUV photons. For these conditions we demonstrated the importance of environmental interactions when atmospheric pressure plasma sources are used to modify biomolecules. This is evident from both gas phase characterization data and in-situ surface characterization of treated biomolecules. Environmental interactions can produce unexpected outcomes due to the complexity of reactions of reactive species with the atmosphere which determines the composition of reactive fluxes and atomistic changes of biomolecules. Overall, this work clarified a richer spectrum of scientific opportunities and challenges for the field of low temperature plasma-biomolecule surface interactions than initially anticipated, in particular for plasma sources operating at atmospheric pressure. The insights produced in this work, e.g. demonstration of the importance of environmental interactions, are generally important for applications of APP to materials modifications. Thus one major contributions of this research has been the establishment of methodologies to more systematically study the interaction of plasma with bio-molecules. In particular, our studies of atmospheric pressure plasma sources using very well-defined experimental conditions enabled to combine atomistic surface modifications of biomolecules with changes in their biological function. The clarification of the role of ions, VUV photons and radicals in deactivation of biomolecules during low pressure and atmospheric pressure plasma-biomolecule interaction has broad implications, e.g. for the emerging field of plasma medicine. The development of methods to detect the effects of plasma treatment on immune-active biomolecules will be helpful in many future studies.« less

Numerical studies of wall–plasma interactions and ionization phenomena in an ablative pulsed plasma thruster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Lei; School of Astronautics, Beihang University, Beijing 100191; Zeng, Guangshang

2016-07-15

Wall–plasma interactions excited by ablation controlled arcs are very critical physical processes in pulsed plasma thrusters (PPTs). Their effects on the ionization processes of ablated vapor into discharge plasma directly determine PPT performances. To reveal the physics governing the ionization phenomena in PPT discharge, a modified model taking into account the pyrolysis effect of heated polytetrafluoroethylene propellant on the wall–plasma interactions was developed. The feasibility of the modified model was analyzed by creating a one-dimensional simulation of a rectangular ablative PPT. The wall–plasma interaction results based on this modified model were found to be more realistic than for the unmodifiedmore » model; this reflects the dynamic changes of the inflow parameters during discharge in our model. Furthermore, the temporal and spatial variations of the different plasma species in the discharge chamber were numerically studied. The numerical studies showed that polytetrafluoroethylene plasma was mainly composed of monovalent ions; carbon and fluorine ions were concentrated in the upstream and downstream discharge chamber, respectively. The results based on this modified model were in good agreement with the experimental formation times of the various plasma species. A large number of short-lived and highly ionized carbon and fluorine species (divalent and trivalent ions) were created during initial discharge. These highly ionized species reached their peak density earlier than the singly ionized species.« less

Surface modification of ethylene-co-tetrafluoroethylene copolymer (ETFE) by plasma

NASA Astrophysics Data System (ADS)

Inagaki, N.

2003-08-01

Surface modification of ETFE surfaces by remote H 2, O 2 and Ar plasmas were investigated from the viewpoint of selective modification of CH 2-CH 2 or CF 2-CF 2 component. The remote H 2 and Ar plasmas modified effectively ETFE surfaces into hydrophilic, but the remote O 2 plasma did not. The remote H 2 plasma interacted with CF 2 component rather than CH 2 component in ETFE. The remote O 2 plasma interacted with CH 2 component as well as CF 2 component in ETFE chains.

Recent advances in plasma modeling for space applications

NASA Astrophysics Data System (ADS)

Srinivasan, Bhuvana; Scales, Wayne; Cagas, Petr; Glesner, Colin

2017-02-01

This paper presents a brief overview of the application of advanced plasma modeling techniques to several space science and engineering problems currently of significant interest. Recent advances in both kinetic and fluid modeling provide the ability to study a wide variety of problems that may be important to space plasmas including spacecraft-environment interactions, plasma-material interactions for propulsion systems such as Hall thrusters, ionospheric plasma instabilities, plasma separation from magnetic nozzles, active space experiments, and a host of additional problems. Some of the key findings are summarized here.

Scaling of plasma-body interactions in low Earth orbit

NASA Astrophysics Data System (ADS)

Capon, C. J.; Brown, M.; Boyce, R. R.

2017-04-01

This paper derives the generalised set of dimensionless parameters that scale the interaction of an unmagnetised multi-species plasma with an arbitrarily charged object - the application in this work being to the interaction of the ionosphere with Low Earth Orbiting (LEO) objects. We find that a plasma with K ion species can be described by 1 + 4 K independent dimensionless parameters. These parameters govern the deflection and coupling of ion species k , the relative electrical shielding of the body, electron energy, and scaling of temporal effects. The general shielding length λ ϕ is introduced, which reduces to the Debye length in the high-temperature (weakly coupled) limit. The ability of the scaling parameters to predict the self-similar transformations of single and multi-species plasma interactions is demonstrated numerically using pdFOAM, an electrostatic Particle-in-Cell—Direct Simulation Monte Carlo code. The presented scaling relationships represent a significant generalisation of past work, linking low and high voltage plasma phenomena. Further, the presented parameters capture the scaling of multi-species plasmas with multiply charged ions, demonstrating previously unreported scaling relationship transformations. The implications of this work are not limited to LEO plasma-body interactions but apply to processes governed by the Vlasov-Maxwell equations and represent a framework upon which to incorporate the scaling of additional phenomena, e.g., magnetism and charging.

Numerical studies on alpha production from high energy proton beam interaction with Boron

NASA Astrophysics Data System (ADS)

Moustaizis, S. D.; Lalousis, P.; Hora, H.; Korn, G.

2017-05-01

Numerical investigations on high energy proton beam interaction with high density Boron plasma allows to simulate conditions concerning the alpha production from recent experimental measurements . The experiments measure the alpha production due to p11B nuclear fusion reactions when a laser-driven high energy proton beam interacts with Boron plasma produced by laser beam interaction with solid Boron. The alpha production and consequently the efficiency of the process depends on the initial proton beam energy, proton beam density, the Boron plasma density and temperature, and their temporal evolution. The main advantage for the p11B nuclear fusion reaction is the production of three alphas with total energy of 8.9 MeV, which could enhance the alpha heating effect and improve the alpha production. This particular effect is termed in the international literature as the alpha avalanche effect. Numerical results using a multi-fluid, global particle and energy balance, code shows the alpha production efficiency as a function of the initial energy of the proton beam, the Boron plasma density, the initial Boron plasma temperature and the temporal evolution of the plasma parameters. The simulations enable us to determine the interaction conditions (proton beam - B plasma) for which the alpha heating effect becomes important.

Multi-species hybrid modeling of plasma interactions at Io and Europa

NASA Astrophysics Data System (ADS)

Sebek, O.; Travnicek, P. M.; Walker, R. J.; Hellinger, P.

2017-12-01

We study the plasma interactions of Galilean satellites, Io and Europa, by means of multi-species global hybrid simulations. For both satellites we consider multi-species background plasma composed of oxygen and sulphur ions and multi-component neutral atmospheres. We consider ionization processes of the neutral atmosphere which is then a source of dense population of pick-up ions. We apply variable background plasma conditions (density, temperature, magnetic field magnitude and orientation) in order to cover the variability in conditions experienced by the satellites when located in different regions of the Jovian plasma torus. We examine global structure of the interactions, formation of Alfvén wings, development of temperature anisotropies and corresponding instabilities, and the fine phenomena caused by the multi-specie nature of the plasma. The results are in good agreement with in situ measurements of magnetic field and plasma density made by the Galileo spacecraft.

Nanowelding and patterning of silver nanowires via mask-free atmospheric cold plasma-jet scanning

NASA Astrophysics Data System (ADS)

Liu, Lang; Li, Han-Yu; Ye, Dong; Yu, Yao; Liu, Lin; Wu, Yue

2017-06-01

Silver nanowire (AgNW) thin film is a promising candidate to replace traditional indium tin oxide in optoelectronics applications. To date however, the widespread application of AgNW thin film is limited by the weak point contacts between individual AgNWs and the lack of facile patterning techniques. Here, we demonstrate a novel and facile method to not only nanoweld AgNW junctions but also pattern AgNW thin films via mask-free cold plasma-jet scanning in ambient conditions. After the plasma-jet nanowelding treatment, the morphology of AgNWs change substantially and the junctions are welded together. The nanowelded AgNWs-based thin film shows enhanced electrical and mechanical properties. On the other hand, after the plasma-jet patterning treatment, the AgNWs are etched and transformed into separated large particles. Different kinds of patterns are produced via this patterning technique. At last, a simple light emitting diode circuit is fabricated to demonstrate the suitability of the nanowelded and patterned AgNW electrodes for flexible electronic devices.

Simulated performance of the optical Thomson scattering diagnostic designed for the National Ignition Facility.

PubMed

Ross, J S; Datte, P; Divol, L; Galbraith, J; Froula, D H; Glenzer, S H; Hatch, B; Katz, J; Kilkenny, J; Landen, O; Manuel, A M; Molander, W; Montgomery, D S; Moody, J D; Swadling, G; Weaver, J

2016-11-01

An optical Thomson scattering diagnostic has been designed for the National Ignition Facility to characterize under-dense plasmas. We report on the design of the system and the expected performance for different target configurations. The diagnostic is designed to spatially and temporally resolve the Thomson scattered light from laser driven targets. The diagnostic will collect scattered light from a 50 × 50 × 200 μm volume. The optical design allows operation with different probe laser wavelengths. A deep-UV probe beam (λ 0 = 210 nm) will be used to Thomson scatter from electron plasma densities of ∼5 × 10 20 cm -3 while a 3ω probe will be used for plasma densities of ∼1 × 10 19 cm -3 . The diagnostic package contains two spectrometers: the first to resolve Thomson scattering from ion acoustic wave fluctuations and the second to resolve scattering from electron plasma wave fluctuations. Expected signal levels relative to background will be presented for typical target configurations (hohlraums and a planar foil).

Experimental launcher facility - ELF-I: Design and operation

NASA Astrophysics Data System (ADS)

Deis, D. W.; Ross, D. P.

1982-01-01

In order to investigate the general area of ultra-high-current density, high-velocity sliding contacts as applied to electromagnetic launcher armatures, a small experimental launcher, ELF-I, has been developed, and preliminary experiments have been performed. The system uses a 36 kJ, 5 kV capacitor bank as a primary pulse power source. When used in conjunction with a 5-microhenry pulse conditioning coil, a 100-kA peak current and 10-ms-wide pulse is obtained. A three-station 150 kV flash X-ray system is operational for obtaining in-bore photographs of the projectiles. Experimental results obtained for both metal and plasma armatures at sliding velocities of up to 1 km/s are discussed with emphasis on armature-rail interactions.

Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

NASA Astrophysics Data System (ADS)

Hohenberger, M.; Albert, F.; Palmer, N. E.; Lee, J. J.; Döppner, T.; Divol, L.; Dewald, E. L.; Bachmann, B.; MacPhee, A. G.; LaCaille, G.; Bradley, D. K.; Stoeckl, C.

2014-11-01

In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic-a multichannel, hard x-ray spectrometer operating in the 20-500 keV range-has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ˜300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U Kβ). The detectors impulse response function was measured in situ on NIF short-pulse (˜90 ps) experiments, and in off-line tests.

Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowe, D. R.; Hagen, E. C.; Meehan, B. T.

2013-06-18

Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentallymore » verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.« less

Simulation study of enhancing laser driven multi-keV line-radiation through application of external magnetic fields

DOE PAGES

Kemp, G. E.; Colvin, J. D.; Blue, B. E.; ...

2016-10-20

Here, we present a path forward for enhancing laser driven, multi-keV line-radiation from mid- to high-Z, sub-quarter-critical density, non-equilibrium plasmas through inhibited thermal transport in the presence of an externally generated magnetic field. Preliminary simulations with Kr and Ag suggest that as much as 50%–100% increases in peak electron temperatures are possible—without any changes in laser drive conditions—with magnetized interactions. The increase in temperature results in ~2–3× enhancements in laser-to-x-ray conversion efficiency for K-shell emission with simultaneous ≲4× reduction in L-shell emission using current field generation capabilities on the Omega laser and near-term capabilities on the National Ignition Facility laser.more » Increased plasma temperatures and enhanced K-shell emission are observed to come at the cost of degraded volumetric heating. Such enhancements in high-photon-energy x-ray sources could expand the existing laser platforms for increasingly penetrating x-ray radiography.« less

Topside enhancements of the ionline in response to high-power HF-radio wave pumping at high latitudes

NASA Astrophysics Data System (ADS)

Rexer, Theresa; Gustavsson, Björn; Grydeland, Tom; Rietveld, Mike; Leyser, Thomas; Brändström, Urban; Sergienko, Tima

2017-04-01

A high power, high frequency heating experiment of the polar ionosphere was conducted in Tromsø, Norway in March 2016. The wave-plasma interactions were observed with the European Incoherent SCATer UHF radar co-located with the heating facility. HF pulses in a 3 minute ON 3 minute OFF cycles were transmitted, sweeping frequencies in 10 and 20 kHz steps from just below to just above the 3rd and 4th multiples of the F-region gyro-frequency. Several interesting features have been found in the radar measurements of the backscatter from the heated plasma. In agreement with current theory we observed an enhanced ionline near the HF reflection height on the bottom-side of the F layer. Simultaneously, a less intense, but clearly visible, ionline enhancement was observed approximately 100 km above this bottom-side enhancement for several 3 minute sweep pulses. We present the observations and discuss the top-side enhanced ion-line in relation to Z and L-mode propagation through the F-region peak.

Experiments on the interaction of heavy ions with dense plasma at GSI-Darmstadt

NASA Astrophysics Data System (ADS)

Stöckl, C.; Boine-Frankenheim, O.; Geißel, M.; Roth, M.; Wetzler, H.; Seelig, W.; Iwase, O.; Spiller, P.; Bock, R.; Süß, W.; Hoffmann, D. H. H.

One of the main objectives of the experimental plasma physics activities at the Gesellschaft für Schwerionenforschung (GSI) are the interaction processes of heavy ions with dense ionized matter. Gas-discharge plasma targets were used for energy loss and charge state measurements in a regime of electron density and temperature up to 10 19 cm -3 and 20 eV, respectively. An improved model of the charge exchange processes in fully ionized hydrogen plasma, taking into account multiple excited electronic configurations which subsequently ionize, has removed the discrepancies of previous theoretical descriptions. The energy loss of the ion beam in partially ionized plasmas such as argon was found to agree very well with our simple theoretical model based on the modified Bethe-Bloch theory. A new setup with a 100 J/5 GW Nd-glass laser now provides access to density ranges up to 10 21 cm -3 and temperatures of up to 100 eV. First results of interaction experiments with laser-produced plasma are presented. To fully exploit the experimental possibilities of the new laser-plasma setup both improved charge state detection systems and better plasma diagnostics are indispensable. Present developments and future possibilities in these fields are presented. This paper summarizes the following contributions: Interaction of heavy-ion beams with laser plasma by C. Stöckl et al. Energy Loss of Heavy Ions in a laser-produced plasma by M. Roth et al. Charge state measurements of heavy ions passing a laser produced plasma with high time resolution by W. Süß et al. Plasma diagnostics for laser-produced plasma by O. Iwase et al. Future possibilities of plasma diagnostics at GSI by M. Geißel et al.

Recent Science Campaigns at HAARP

NASA Astrophysics Data System (ADS)

McCoy, R. P.; Bristow, W. A.; Fallen, C. T.

2017-12-01

Experiments in HF ionospheric heating using the High­frequency Active Auroral Research Program (HAARP) facilities have tremendous potential for informing our investigation of the Earth's upper atmosphere, ionosphere, and magnetosphere. They provide a unique opportunity for quantifying and modeling the multi­scale coupled processes that characterize the interactions between the plasma in near­Earth space, the Earth's magnetic field, and the neutral gasses of the atmosphere. Physical parameters of the region are often difficult to measure with ground­based instruments, and the measurements that are possible are often poorly resolved in range or time or unavailable outside narrow altitude regimes. HF ionospheric modification experiments allow us to measure ionospheric and thermospheric state parameters more systematically and over a broader range of conditions than would otherwise be possible. HAARP is the world's most powerful and most flexible HF transmitting facility, capable of generating 3.6 MW of RF power over a frequency range from about 2 MHz to about 10 MHz. The electronic phased array antenna provides the ability to direct the RF energy to a large region of the sky above Alaska. HAARP was constructed through a research program managed by the Air Force Research Laboratory (AFRL), and the Office of Naval Research (ONR). It was jointly funded by AFRL, ONR, and the Defense Advanced Projects Research Agency (DARPA). These agencies ended of their program of HAARP research in 2014, and donated the site equipment to the University of Alaska, Fairbanks (UAF), in the summer of 2015, who now operate the facility as an international observatory for radio plasma heating and subauroral physics. Since taking control of HAARP, UAF has carried out research campaigns in February 2017, and September 2017. The topics investigated in the campaigns included the physics of ionospheric irregularities (FAI), the stimulated electromagnetic emissions (SEE), generation of optical emissions from the heated region, and technological impacts of irregularities. This paper will give an overview of the status of the facility and will present preliminary results from the experiments carried out in the campaigns.

Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

NASA Astrophysics Data System (ADS)

Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2016-09-01

Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

Numerical band structure calculations of plasma metamaterials

NASA Astrophysics Data System (ADS)

Pederson, Dylan; Kourtzanidis, Konstantinos; Raja, Laxminarayan

2015-09-01

Metamaterials (MM) are materials engineered to display negative macroscopic permittivity and permeability. These materials allow for designed control over electromagnetic energy flow, especially at frequencies where natural materials do not interact. Plasmas have recently found application in MM as a negative permittivity component. The permittivity of a plasma depends on its electron density, which can be controlled by an applied field. This means that plasmas can be used in MM to actively control the transmission or reflection of incident waves. This work focuses on a plasma MM geometry in which microplasmas are generated in perforations in a metal plate. We characterizethis material by its band structure, which describes its interaction with incident waves. The plasma-EM interactions are obtained by coupling Maxwell's equations to a simplified plasma momentum equation. A plasma density profile is prescribed, and its effect on the band structure is investigated. The band structure calculations are typically done for static structures, whereas our current density responds to the incident waves. The resulting band structures are compared with experimental results.

Studying astrophysical particle acceleration with laser-driven plasmas

NASA Astrophysics Data System (ADS)

Fiuza, Frederico

2016-10-01

The acceleration of non-thermal particles in plasmas is critical for our understanding of explosive astrophysical phenomena, from solar flares to gamma ray bursts. Particle acceleration is thought to be mediated by collisionless shocks and magnetic reconnection. The microphysics underlying these processes and their ability to efficiently convert flow and magnetic energy into non-thermal particles, however, is not yet fully understood. By performing for the first time ab initio 3D particle-in-cell simulations of the interaction of both magnetized and unmagnetized laser-driven plasmas, it is now possible to identify the optimal parameters for the study of particle acceleration in the laboratory relevant to astrophysical scenarios. It is predicted for the Omega and NIF laser conditions that significant non-thermal acceleration can occur during magnetic reconnection of laser-driven magnetized plasmas. Electrons are accelerated by the electric field near the X-points and trapped in contracting magnetic islands. This leads to a power-law tail extending to nearly a hundred times the thermal energy of the plasma and that contains a large fraction of the magnetic energy. The study of unmagnetized interpenetrating plasmas also reveals the possibility of forming collisionless shocks mediated by the Weibel instability on NIF. Under such conditions, both electrons and ions can be energized by scattering out of the Weibel-mediated turbulence. This also leads to power-law spectra that can be detected experimentally. The resulting experimental requirements to probe the microphysics of plasma particle acceleration will be discussed, paving the way for the first experiments of these important processes in the laboratory. As a result of these simulations and theoretical analysis, there are new experiments being planned on the Omega, NIF, and LCLS laser facilities to test these theoretical predictions. This work was supported by the SLAC LDRD program and DOE Office of Science, Fusion Energy Science (FWP 100182).

Hybrid-PIC modeling of laser-plasma interactions and hot electron generation in gold hohlraum walls

NASA Astrophysics Data System (ADS)

Thoma, C.; Welch, D. R.; Clark, R. E.; Rose, D. V.; Golovkin, I. E.

2017-06-01

The walls of the hohlraum used in experiments at the national ignition facility are heated by laser beams with intensities ˜ 10 15 W/cm2, a wavelength of ˜ 1 / 3 μm, and pulse lengths on the order of a ns, with collisional absorption believed to be the primary heating mechanism. X-rays generated by the hot ablated plasma at the gold walls are then used to implode a target in the hohlraum interior. In addition to the collisional absorption of laser energy at the walls, non-linear laser-plasma interactions (LPI), such as stimulated Raman scattering and two plasmon decay, are believed to generate a population of supra-thermal electrons which, if present in the hohlraum, can have a deleterious effect on target implosion. We describe results of hohlraum modeling using a hybrid particle-in-cell code. To enable this work, new particle-based algorithms for a multiple-ion magneto-hydrodynamic (MHD) treatment, and a particle-based ray-tracing model were developed. The use of such hybrid methods relaxes the requirement to resolve the laser wavelength, and allows for relatively large-scale hohlraum simulations with a reasonable number of cells. But the non-linear effects which are believed to be the cause of hot electron generation can only be captured by fully kinetic simulations with good resolution of the laser wavelength. For this reason, we employ a two-tiered approach to hohlraum modeling. Large-scale simulations of the collisional absorption process can be conducted using the fast quasi-neutral MHD algorithm with fluid particle species. From these simulations, we can observe the time evolution of the hohlraum walls and characterize the density and temperature profiles. From these results, we can transition to smaller-scale highly resolved simulations using traditional kinetic particle-in-cell methods, from which we can fully model all of the non-linear laser-plasma interactions, as well as assess the details of the electron distribution function. We find that vacuum hohlraums should be stable to both two plasmon decay and stimulated Raman scattering instabilities for intensities ≤ 10 15 W/cm2. In gas-filled hohlraums, shocks may be induced in the blowoff gold plasma, which leads to more complex density and temperatures profiles. The resulting effect on LPI stability depends strongly on the details of the profile, and it is possible for the gas-filled hohlraum to become unstable to two plasmon decay at 1015 W/cm2 if the quarter-critical surface reaches temperatures exceeding 1 keV.

Simulations of beam-matter interaction experiments at the CERN HiRadMat facility and prospects of high-energy-density physics research.

PubMed

Tahir, N A; Burkart, F; Shutov, A; Schmidt, R; Wollmann, D; Piriz, A R

2014-12-01

In a recent publication [Schmidt et al., Phys. Plasmas 21, 080701 (2014)], we reported results on beam-target interaction experiments that have been carried out at the CERN HiRadMat (High Radiation to Materials) facility using extended solid copper cylindrical targets that were irradiated with a 440-GeV proton beam delivered by the Super Proton Synchrotron (SPS). On the one hand, these experiments confirmed the existence of hydrodynamic tunneling of the protons that leads to substantial increase in the range of the protons and the corresponding hadron shower in the target, a phenomenon predicted by our previous theoretical investigations [Tahir et al., Phys. Rev. ST Accel. Beams 25, 051003 (2012)]. On the other hand, these experiments demonstrated that the beam heated part of the target is severely damaged and is converted into different phases of high energy density (HED) matter, as suggested by our previous theoretical studies [Tahir et al., Phys. Rev. E 79, 046410 (2009)]. The latter confirms that the HiRadMat facility can be used to study HED physics. In the present paper, we give details of the numerical simulations carried out to understand the experimental measurements. These include the evolution of the physical parameters, for example, density, temperature, pressure, and the internal energy in the target, during and after the irradiation. This information is important in order to determine the region of the HED phase diagram that can be accessed in such experiments. These simulations have been done using the energy deposition code fluka and a two-dimensional hydrodynamic code, big2, iteratively.

Exact solution of CKP equation and formation and interaction of two solitons in pair-ion-electron plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batool, Nazia; Jahangir, R.; National Center of Physics

In the present investigation, cylindrical Kadomstev-Petviashvili (CKP) equation is derived in pair-ion-electron plasmas to study the propagation and interaction of two solitons. Using a novel gauge transformation, two soliton solutions of CKP equation are found analytically by using Hirota's method and to the best of our knowledge have been used in plasma physics for the first time. Interestingly, it is observed that unlike the planar Kadomstev-Petviashvili (KP) equation, the CKP equation admits horseshoe-like solitary structures. Another non-trivial feature of CKP solitary solution is that the interaction parameter gets modified by the plasma parameters contrary to the one obtained for Korteweg–demore » Vries equation. The importance of the present investigation to understand the formation and interaction of solitons in laboratory produced pair plasmas is also highlighted.« less

Space environment effects on polymers in low earth orbit

NASA Astrophysics Data System (ADS)

Grossman, E.; Gouzman, I.

2003-08-01

Polymers are widely used in space vehicles and systems as structural materials, thermal blankets, thermal control coatings, conformal coatings, adhesives, lubricants, etc. The low earth orbit (LEO) space environment includes hazards such as atomic oxygen, UV radiation, ionizing radiation (electrons, protons), high vacuum, plasma, micrometeoroids and debris, as well as severe temperature cycles. Exposure of polymers and composites to the space environment may result in different detrimental effects via modification of their chemical, electrical, thermal, optical and mechanical properties as well as surface erosion. The high vacuum induces material outgassing (e.g. low-molecular weight residues, plasticizers and additives) and consequent contamination of nearby surfaces. The present work reviews the LEO space environment constituents and their interactions with polymers. Examples of degradation of materials exposed in ground simulation facilities are presented. The issues discussed include the erosion mechanisms of polymers, formation of contaminants and their interaction with the space environment, and protection of materials from the harsh space environment.

Electromagnetic Pulses Generated From Laser Target Interactions at Shenguang II Laser Facility

NASA Astrophysics Data System (ADS)

Yang, Jinwen; Li, Tingshuai; Yi, Tao; Wang, Chuanke; Yang, Ming; Yang, Weiming; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

2016-10-01

Significant electromagnetic pulses (EMP) can be generated by the intensive laser irradiating solid targets in inertial confinement fusion (ICF). To evaluate the EMP intensity and distribution in and outside the laser chamber, we designed and fabricated a discone antenna with ultra-wide bands of over 10 GHz. The return loss (S11 parameter) of this antenna was below -10 dB and could even achieve under -30 dB at 3.1 GHz. The EMP intensity in this study at 80 cm and 40 cm away from the target chamber center (TCC) reached 400 kV/m and 2000 kV/m. The current results are expected to offer preliminary information to study physics regarding laser plasma interactions and will also lay experimental foundation for EMI shielding design to protect various diagnostics. supported by the Fundamental Research Funds for the Central Universities of China (No. ZYGX2015J108) and National Natural Science Foundation of China (Nos. 11575166 and 51581140)

Initial Operation of the Miniaturized Inductively Heated Plasma Generator IPG6

NASA Astrophysics Data System (ADS)

Dropmann, Michael; Herdrich, Georg; Laufer, Rene; Koch, Helmut; Gomringer, Chris; Cook, Mike; Schmoke, Jimmy; Matthews, Lorin; Hyde, Truell

2012-10-01

In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma wind tunnel facilities of similar type have been established using the inductively heated plasma source IPG6 which is based on proven IRS designs. The facility at Baylor University (IPG6-B) works at a frequency of 13.56 MHz and a maximum power of 15 kW. A vacuum pump of 160m^3/h in combination with a butterfly valve allows pressure control in a wide range. First experiments have been conducted with Air, O2 and N2 as working gases and volumetric flow rates of up to 14 L/min at pressures of a few 100 Pa, although pressures below 1 Pa are achievable at lower flow rates. The maximum tested electric power so far was 8 kW. Plasma powers and total pressures in the plasma jet have been obtained. In the near future the set up of additional diagnostics, the use of other gases (i.e. H2, He), and the integration of a dust particle accelerator are planned. The intended fields of research are basic investigation in thermo-chemistry and plasma radiation, space plasma environments and high heat fluxes e.g. in fusion devices or during atmospheric entry of spacecraft.

Preliminary feasibility study of pallet-only mode for magnetospheric and plasmas in space payloads, volume 4

NASA Technical Reports Server (NTRS)

1976-01-01

Results of studies performed on the magnetospheric and plasma portion of the AMPS are presented. Magnetospheric and plasma in space experiments and instruments are described along with packaging (palletization) concepts. The described magnetospheric and plasma experiments were considered as separate entities. Instrumentation ospheric and plasma experiments were considered as separate entities. Instrumentation requirements and operations were formulated to provide sufficient data for unambiguous interpretation of results without relying upon other experiments of the series. Where ground observations are specified, an assumption was made that large-scale additions or modifications to existing facilities were not required.

Differential rotation of plasma in the GOL-3 multiple-mirror trap during injection of a relativistic electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanov, I. A., E-mail: I.A.Ivanov@inp.nsk.su; Burdakov, A. V.; Burmasov, V. S.

2017-02-15

Results of spectral and magnetic diagnostics of plasma differential rotation in the GOL-3 multiplemirror trap are presented. It is shown that the maximum frequency of plasma rotation about the longitudinal axis reaches 0.5 MHz during the injection of a relativistic electron beam into the plasma. The data of two diagnostics agree if there is a region with a higher rotation frequency near the boundary of the electron beam. Plasma differential rotation can be an additional factor stabilizing interchange modes in the GOL-3 facility.

Development of atmospheric pressure large area plasma jet for sterilisation and investigation of molecule and plasma interaction

NASA Astrophysics Data System (ADS)

Zerbe, Kristina; Iberler, Marcus; Jacoby, Joachim; Wagner, Christopher

2016-09-01

The intention of the project is the development and improvement of an atmospheric plasma jet based on various discharge forms (e.g. DBD, RF, micro-array) for sterilisation of biomedical equipment and investigation of biomolecules under the influence of plasma stress. The major objective is to design a plasma jet with a large area and an extended length. Due to the success on small scale plasma sterilisation the request of large area plasma has increased. Many applications of chemical disinfection in environmental and medical cleaning could thereby be complemented. Subsequently, the interaction between plasma and biomolecules should be investigated to improve plasma strerilisation. Special interest will be on non equilibrium plasma electrons affecting the chemical bindings of organic molecules.

Electron-Driven Processes: From Single Collision Experiments to High-Pressure Discharge Plasmas

NASA Astrophysics Data System (ADS)

Becker, Kurt

2001-10-01

Plasmas are complex systems which consist of various groups of interacting particles (neutral atoms and molecules in their ground states and in excite states, electrons, and positive and negative ions). In principle, one needs to understand and describe all interactions between these particles in order to model the properties of the plasma and to predict its behavior. However, two-body interactions are often the only processes of relevance and only a subset of all possible collisional interactions are important. The focus of this talk is on collisional and radiative processes in low-temperature plasmas, both at low and high pressures. We will limit the discussion (i) to ionization and dissociation processes in molecular low-pressure plasmas and (ii) to collisional and radiative processes in high-pressure plasmas in rare gases and mixtures of rare gases and N2, O2, and H2. Electron-impact dissociation processes can be divided into dissociative excitation and dissociation into neutral ground-state fragments. Neutral molecular dissociation has only recently received attention from experimentalists and theorists because of the serious difficulties associated with the investigation of these processes. Collisional and radiative processes in high-pressure plasmas provide a fertile environment to the study of interactions that go beyond binary collisions involving ground-state species. Step-wise processes and three-body collisions begin to dominate the behavior of such plasmas. We will discuss examples of such processes as they relate to high-pressure rare gas discharge plasmas. Work supported by NSF, DOE, DARPA, NASA, and ABA Inc.

Synergistic effects of plasma-catalyst interactions for CH4 activation.

PubMed

Kim, Jongsik; Go, David B; Hicks, Jason C

2017-05-24

The elucidation of catalyst surface-plasma interactions is a challenging endeavor and therefore requires thorough and rigorous assessment of the reaction dynamics on the catalyst in the plasma environment. The first step in quantifying and defining catalyst-plasma interactions is a detailed kinetic study that can be used to verify appropriate reaction conditions for comparison and to discover any unexpected behavior of plasma-assisted reactions that might prevent direct comparison. In this paper, we provide a kinetic evaluation of CH 4 activation in a dielectric barrier discharge plasma in order to quantify plasma-catalyst interactions via kinetic parameters. The dry reforming of CH 4 with CO 2 was studied as a model reaction using Ni supported on γ-Al 2 O 3 at temperatures of 790-890 K under atmospheric pressure, where the partial pressures of CH 4 (or CO 2 ) were varied over a range of ≤25.3 kPa. Reaction performance was monitored by varying gas hourly space velocity, plasma power, bulk gas temperature, and reactant concentration. After correcting for gas-phase plasma reactions, a linear relationship was observed in the log of the measured rate constant with respect to reciprocal power (1/power). Although thermal catalysis displays typical Arrhenius behavior for this reaction, plasma-assisted catalysis occurs from a complex mixture of sources and shows non-Arrhenius behavior. However, an energy barrier was obtained from the relationship between the reaction rate constant and input power to exhibit ≤∼20 kJ mol -1 (compared to ∼70 kJ mol -1 for thermal catalysis). Of additional importance, the energy barriers measured during plasma-assisted catalysis were relatively consistent with respect to variations in total flow rates, types of diluent, or bulk reaction temperature. These experimental results suggest that plasma-generated vibrationally-excited CH 4 favorably interacts with Ni sites at elevated temperatures, which helps reduce the energy barrier required to activate CH 4 and enhance CH 4 reforming rates.

Study of plasma formation in CW CO2 laser beam-metal surface interaction

NASA Astrophysics Data System (ADS)

Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

1994-04-01

An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

Control of dispersed-phase temperature in plasma flows by the spectral-brightness pyrometry method

NASA Astrophysics Data System (ADS)

Dolmatov, A. V.; Gulyaev, I. P.; Gulyaev, P. Yu; Iordan, V. I.

2016-02-01

In the present work, we propose a new method for measuring the distribution of temperature in the ensembles of condensed-phase particles in plasma spray flows. Interrelation between the spectral temperature of the particles and the distribution of camera brightness signal is revealed. The established inter-relation enables an in-situ calibration of measuring instruments using the objects under study. The spectral-brightness pyrometry method was approbated on a Plazer plasma-arc wire spraying facility at the Paton Institute of Electrical Welding (Ukrainian Academy of Sciences, Kiev) and on the Thermoplasma 50-1 powder spraying facility at the Institute of Theoretical and Applied Mechanics (Russian Academy of Sciences, Siberian Branch, Novosibirsk). The work was supported by the Russian Foundation for Basic Research (Grants Nos. 14-08-90428 and 15-48-00100).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krauz, V. I., E-mail: krauz@nfi.kiae.ru; Mitrofanov, K. N.; Voitenko, D. A.

Results are presented from magnetic probe measurements in the pinching region formed during the compression of the plasma current sheath (PCS) in a discharge in deuterium at the KPF-4-Phoenix plasma focus facility. The fine structure (shock front-magnetic piston) of the PCS and its time evolution in the course of plasma compression toward the facility axis was studied by means of magnetic probes. It is shown that the fraction of the current transported into the axial region by the PCS does not exceed 65% of the total discharge current. The integral neutron yield Y{sub n} is well described by the formulamore » Y{sub n} ≈ (1.5–3) × 10{sup 10}I{sub p}{sup 4}, where I{sub p} (in MA) is the pinch current flowing in the region r ≤ 22 mm.« less

FLARE (Facility for Laboratory Reconnection Experiments): A Major Next-Step for Laboratory Studies of Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W. S.; Bale, S. D.; Carter, T. A.; Crocker, N.; Drake, J. F.; Egedal, J.; Sarff, J.; Wallace, J.; Belova, E.; Ellis, R.; Fox, W. R., II; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C. E.; Que, W.; Ren, Y.; Titus, P.; Yamada, M.; Yoo, J.

2014-12-01

A new intermediate-scale plasma experiment, called the Facility for Laboratory Reconnection Experiments or FLARE, is under construction at Princeton as a joint project by five universities and two national labs to study magnetic reconnection in regimes directly relevant to space, solar and astrophysical plasmas. The currently existing small-scale experiments have been focusing on the single X-line reconnection process in plasmas either with small effective sizes or at low Lundquist numbers, both of which are typically very large in natural plasmas. These new regimes involve multiple X-lines as guided by a reconnection "phase diagram", in which different coupling mechanisms from the global system scale to the local dissipation scale are classified into different reconnection phases [H. Ji & W. Daughton, Phys. Plasmas 18, 111207 (2011)]. The design of the FLARE device is based on the existing Magnetic Reconnection Experiment (MRX) at Princeton (http://mrx.pppl.gov) and is to provide experimental access to the new phases involving multiple X-lines at large effective sizes and high Lundquist numbers, directly relevant to space and solar plasmas. The motivating major physics questions, the construction status, and the planned collaborative research especially with space and solar research communities will be discussed.

FLARE (Facility for Laboratory Reconnection Experiments): A Major Next-Step for Laboratory Studies of Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Ji, Hantao; Bhattacharjee, A.; Prager, S.; Daughton, W.; Bale, Stuart D.; Carter, T.; Crocker, N.; Drake, J.; Egedal, J.; Sarff, J.; Fox, W.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.

2015-04-01

A new intermediate-scale plasma experiment, called the Facility for Laboratory Reconnection Experiments or FLARE (flare.pppl.gov), is under construction at Princeton as a joint project by five universities and two national labs to study magnetic reconnection in regimes directly relevant to heliophysical and astrophysical plasmas. The currently existing small-scale experiments have been focusing on the single X-line reconnection process in plasmas either with small effective sizes or at low Lundquist numbers, both of which are typically very large in natural plasmas. These new regimes involve multiple X-lines as guided by a reconnection "phase diagram", in which different coupling mechanisms from the global system scale to the local dissipation scale are classified into different reconnection phases [H. Ji & W. Daughton, Phys. Plasmas 18, 111207 (2011)]. The design of the FLARE device is based on the existing Magnetic Reconnection Experiment (MRX) (mrx.pppl.gov) and is to provide experimental access to the new phases involving multiple X-lines at large effective sizes and high Lundquist numbers, directly relevant to magnetospheric, solar wind, and solar coronal plasmas. After a brief summary of recent laboratory results on the topic of magnetic reconnection, the motivating major physics questions, the construction status, and the planned collaborative research especially with heliophysics communities will be discussed.

Presentation Stations of the General Atomics Fusion Educational Program

NASA Astrophysics Data System (ADS)

Lee, R. L.; Fusion Group Education Outreach Team

1996-11-01

The General Atomics Fusion Group's Educational Program has been actively promoting fusion science and applications throughout San Diego County's secondary school systems for over three years. The educational program allows many students to learn more about nuclear fusion science, its applications, and what it takes to become an active participant in an important field of study. It also helps educators to better understand how to teach fusion science in their classroom. Tours of the DIII--D facility are a centerpiece of the program. Over 1000 students visited the DIII--D research facility during the 1995--1996 school year for a half-day of presentations, discussions, and hands-on learning. Interactive presentations are provided at six different stations by GA scientists and engineers to small groups of students during the tours. Stations include topics on energy, plasma science, the electromagnetic spectrum, radiation and risk assessment, and data acquisition. Included also is a tour of the DIII--D machine hall and model where students can see and discuss many aspects of the tokamak. Portions of each station will be presented and discussed.

Experiments on the transportation of a magnetized plasma stream in the GOL-3 facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Postupaev, V. V., E-mail: V.V.Postupaev@inp.nsk.su; Batkin, V. I.; Burdakov, A. V.

2016-04-15

The program of the deep upgrade of the GOL-3 multiple-mirror trap is presented. The upgrade is aimed at creating a new GOL-NB open trap located at the GOL-3 site and intended to directly demonstrate the efficiency of using multiple-mirror magnetic cells to improve longitudinal plasma confinement in a gasdynamic open trap. The GOL-NB device will consist of a new central trap, adjoint cells with a multiple-mirror magnetic field, and end tanks (magnetic flux expanders). Plasma in the central trap will be heated by neutral beam injection with a power of up to 1.5 MW and duration of 1 ms. Atmore » present, physical experiments directed at developing plasma technologies that are novel for this facility are being carried out using the 6-m-long autonomous part of the GOL-3 solenoid. The aim of this work was to develop a method for filling the central trap with a low-temperature start plasma. Transportation of a plasma stream from an arc source over a distance of 3 m in a uniform magnetic field with an induction of 0.5–4.5 T is demonstrated. In these experiments, the axial plasma density was (1–4) × 10{sup 20} m{sup –3} and the mirror ratio varied from 5 to 60. In general, the experiments confirmed the correctness of the adopted decisions for the start plasma source of the GOL-NB device.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The vision described here builds on the present U.S. activities in fusion plasma and materials science relevant to the energy goal and extends plasma science at the frontier of discovery. The plan is founded on recommendations made by the National Academies, a number of recent studies by the Fusion Energy Sciences Advisory Committee (FESAC), and the Administration’s views on the greatest opportunities for U.S. scientific leadership.This report highlights five areas of critical importance for the U.S. fusion energy sciences enterprise over the next decade: 1) Massively parallel computing with the goal of validated whole-fusion-device modeling will enable a transformation inmore » predictive power, which is required to minimize risk in future fusion energy development steps; 2) Materials science as it relates to plasma and fusion sciences will provide the scientific foundations for greatly improved plasma confinement and heat exhaust; 3) Research in the prediction and control of transient events that can be deleterious to toroidal fusion plasma confinement will provide greater confidence in machine designs and operation with stable plasmas; 4) Continued stewardship of discovery in plasma science that is not expressly driven by the energy goal will address frontier science issues underpinning great mysteries of the visible universe and help attract and retain a new generation of plasma/fusion science leaders; 5) FES user facilities will be kept world-leading through robust operations support and regular upgrades. Finally, we will continue leveraging resources among agencies and institutions and strengthening our partnerships with international research facilities.« less

Ring current dynamics and plasma sheet sources. [magnetic storms

NASA Technical Reports Server (NTRS)

Lyons, L. R.

1984-01-01

The source of the energized plasma that forms in geomagnetic storm ring currents, and ring current decay are discussed. The dominant loss processes for ring current ions are identified as charge exchange and resonant interactions with ion-cyclotron waves. Ring current ions are not dominated by protons. At L4 and energies below a few tens of keV, O+ is the most abundant ion, He+ is second, and protons are third. The plasma sheet contributes directly or indirectly to the ring current particle population. An important source of plasma sheet ions is earthward streaming ions on the outer boundary of the plasma sheet. Ion interactions with the current across the geomagnetic tail can account for the formation of this boundary layer. Electron interactions with the current sheet are possibly an important source of plasma sheet electrons.

Kinetic Theory of quasi-electrostatic waves in non-gyrotropic plasmas

NASA Astrophysics Data System (ADS)

Arshad, K.; Poedts, S.; Lazar, M.

2017-12-01

The orbital angular momentum (OAM) is a trait of helically phased light or helical (twisted) electric field. Lasers carrying orbital angular momentum (OAM) revolutionized many scientific and technological paradigms like microscopy, imaging and ionospheric radar facility to analyze three dimensional plasma dynamics in ionosphere, ultra-intense twisted laser pulses, twisted gravitational waves and astrophysics. This trend has also been investigated in plasma physics. Laguerre-Gaussian type solutions are predicted for magnetic tornadoes and Alfvénic tornadoes which exhibit spiral, split and ring-like morphologies. The ring shape morphology is ideal to fit the observed solar corona, solar atmosphere and Earth's ionosphere. The orbital angular momentum indicates the mediation of electrostatic and electromagnetic waves in new phenomena like Raman and Brillouin scattering. A few years ago, some new effects have been included in studies of orbital angular momentum in plasma regimes such as wave-particle interaction in the presence of helical electric field. Therefore, kinetic studies are carried out to investigate the Landau damping of the waves and growth of the instabilities in the presence helical electric field carrying orbital angular momentum for the Maxwellian distributed plasmas. Recently, a well suited approach involving a kappa distribution function has been adopted to model the twisted space plasmas. This leads to the development of new theoretical grounds for the study of Lorentzian or kappa distributed twisted Langmuir, ion acoustic, dust ion acoustic and dust acoustic modes. The quasi-electrostatic twisted waves have been studied now for the non-gyrotropic dusty plasmas in the presence of the orbital angular momentum of the helical electric field using Generalized Lorentzian or kappa distribution function. The Laguerre-Gaussian (LG) mode function is employed to decompose the perturbed distribution function and electric field into planar (longitudinal) and non-planar (azimuthal) components. The modified Vlasov and Poisson equations are solved to obtain the dielectric function for quasi-electrostatic twisted modes the non-gyrotropic dusty plasmas. Some numerical and graphical analysis is also illustrated for the better understanding of the twisted non-gyrotropic plasmas.

Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

2017-02-01

Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

Dependence of the source performance on plasma parameters at the BATMAN test facility

NASA Astrophysics Data System (ADS)

Wimmer, C.; Fantz, U.

2015-04-01

The investigation of the dependence of the source performance (high jH-, low je) for optimum Cs conditions on the plasma parameters at the BATMAN (Bavarian Test MAchine for Negative hydrogen ions) test facility is desirable in order to find key parameters for the operation of the source as well as to deepen the physical understanding. The most relevant source physics takes place in the extended boundary layer, which is the plasma layer with a thickness of several cm in front of the plasma grid: the production of H-, its transport through the plasma and its extraction, inevitably accompanied by the co-extraction of electrons. Hence, a link of the source performance with the plasma parameters in the extended boundary layer is expected. In order to characterize electron and negative hydrogen ion fluxes in the extended boundary layer, Cavity Ring-Down Spectroscopy and Langmuir probes have been applied for the measurement of the H- density and the determination of the plasma density, the plasma potential and the electron temperature, respectively. The plasma potential is of particular importance as it determines the sheath potential profile at the plasma grid: depending on the plasma grid bias relative to the plasma potential, a transition in the plasma sheath from an electron repelling to an electron attracting sheath takes place, influencing strongly the electron fraction of the bias current and thus the amount of co-extracted electrons. Dependencies of the source performance on the determined plasma parameters are presented for the comparison of two source pressures (0.6 Pa, 0.45 Pa) in hydrogen operation. The higher source pressure of 0.6 Pa is a standard point of operation at BATMAN with external magnets, whereas the lower pressure of 0.45 Pa is closer to the ITER requirements (p ≤ 0.3 Pa).

Inductive and electrostatic acceleration in relativistic jet-plasma interactions.

PubMed

Ng, Johnny S T; Noble, Robert J

2006-03-24

We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma-wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of 2 during the simulation period. Particle acceleration via these mechanisms occurred when the criteria for Weibel instability were satisfied.

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

PubMed Central

Consoli, F.; De Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; Di Giorgio, G.; Ingenito, F.; Verona, C.

2016-01-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation. PMID:27301704

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

NASA Astrophysics Data System (ADS)

Consoli, F.; de Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; di Giorgio, G.; Ingenito, F.; Verona, C.

2016-06-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation.

A small electron beam ion trap/source facility for electron/neutral–ion collisional spectroscopy in astrophysical plasmas

NASA Astrophysics Data System (ADS)

Liang, Gui-Yun; Wei, Hui-Gang; Yuan, Da-Wei; Wang, Fei-Lu; Peng, Ji-Min; Zhong, Jia-Yong; Zhu, Xiao-Long; Schmidt, Mike; Zschornack, Günter; Ma, Xin-Wen; Zhao, Gang

2018-01-01

Spectra are fundamental observation data used for astronomical research, but understanding them strongly depends on theoretical models with many fundamental parameters from theoretical calculations. Different models give different insights for understanding a specific object. Hence, laboratory benchmarks for these theoretical models become necessary. An electron beam ion trap is an ideal facility for spectroscopic benchmarks due to its similar conditions of electron density and temperature compared to astrophysical plasmas in stellar coronae, supernova remnants and so on. In this paper, we will describe the performance of a small electron beam ion trap/source facility installed at National Astronomical Observatories, Chinese Academy of Sciences.We present some preliminary experimental results on X-ray emission, ion production, the ionization process of trapped ions as well as the effects of charge exchange on the ionization.

Plasma Medicine

NASA Astrophysics Data System (ADS)

Laroussi, M.; Kong, M. G.; Morfill, G.; Stolz, W.

2012-05-01

Foreword R. Satava and R. J. Barker; Part I. Introduction to Non-equilibrium Plasma, Cell Biology, and Contamination: 1. Introduction M. Laroussi; 2. Fundamentals of non-equilibrium plasmas M. Kushner and M. Kong; 3. Non-equilibrium plasma sources M. Laroussi and M. Kong; 4. Basic cell biology L. Greene and G. Shama; 5. Contamination G. Shama and B. Ahlfeld; Part II. Plasma Biology and Plasma Medicine: 6. Common healthcare challenges G. Isbary and W. Stolz; 7. Plasma decontamination of surfaces M. Kong and M. Laroussi; 8. Plasma decontamination of gases and liquids A. Fridman; 9. Plasma-cell interaction: prokaryotes M. Laroussi and M. Kong; 10. Plasma-cell interaction: eukaryotes G. Isbary, G. Morfill and W. Stolz; 11. Plasma based wound healing G. Isbary, G. Morfill and W. Stolz; 12. Plasma ablation, surgery, and dental applications K. Stalder, J. Woloszko, S. Kalghatgi, G. McCombs, M. Darby and M. Laroussi; Index.

Radiation Generation from Ultra Intense Laser Plasma Interactions with Solid Density Plasmas for Active Interrogation of Nuclear Materials

NASA Astrophysics Data System (ADS)

Zulick, Calvin Andrew

The development of short pulse high power lasers has led to interest in laser based particle accelerators. Laser produced plasmas have been shown to support quasi-static TeV/m acceleration gradients which are more than four orders of magnitude stronger than conventional accelerators. These high gradients have the potential to allow compact particle accelerators for active interrogation of nuclear material. In order to better understand this application, several experiments have been conducted at the HERCULES and Lambda Cubed lasers as the Center for Ultrafast Optical Science at the University of Michigan. Electron acceleration and bremsstrahlung generation were studied on the Lambda Cubed laser. The scaling of the intensity, angular, and material dependence of bremsstrahlung radiation from an intense (I > 10 18 W/cm2 ) laser-solid interaction has been characterized at energies between 100 keV and 1 MeV. These were the first high resolution (lambda / d lambda > 100) measurements of bremsstrahlung photons from a relativistic laser plasma interaction. The electron populations and bremsstrahlung temperatures were modeled in the particle-in-cell code OSIRIS and the Monte Carlo code MCNPX and were in good agreement with the experimental results. Proton acceleration was studied on the HERCULES laser. The effect of three dimensional perturbations of electron sheaths on proton acceleration was investigated through the use of foil, grid, and wire targets. Hot electron density, as measured with an imaging Cu Kalpha crystal, increased as the target surface area was reduced and was correlated to an increase in the temperature of the accelerated proton beam. Additionally, experiments at the HERCULES laser facility have produced directional neutron beams with energies up to 16.8 (+/-0.3) MeV using (d,n) and (p,n) reactions. Efficient (d,n) reactions required the selective acceleration of deuterons through the introduction of a deuterated plastic or cryogenically frozen D2O layer on the surface of a thin film target. The measured neutron yield was up to 1.0 (+/-0.5) x 107 neutrons/sr with a flux 6.2 (+/-3.7) times higher in the forward direction than at 90 degrees . This demonstrated that femtosecond lasers are capable of providing a time averaged neutron flux equivalent to commercial DD generators with the advantage of a directional beam with picosecond bunch duration.

DOE-HEP Final Report for 2013-2016: Studies of plasma wakefields for high repetition-rate plasma collider, and Theoretical study of laser-plasma proton and ion acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsouleas, Thomas C.; Sahai, Aakash A.

2016-08-08

There were two goals for this funded project: 1. Studies of plasma wakefields for high repetition-rate plasma collider, and 2. Theoretical study of laser-plasma proton and ion acceleration. For goal 1, an analytical model was developed to determine the ion-motion resulting from the interaction of non-linear “blow-out” wakefields excited by beam-plasma and laser-plasma interactions. This is key to understanding the state of the plasma at timescales of 1 picosecond to a few 10s of picoseconds behind the driver-energy pulse. More information can be found in the document. For goal 2, we analytically and computationally analyzed the longitudinal instabilities of themore » laser-plasma interactions at the critical layer. Specifically, the process of “Doppler-shifted Ponderomotive bunching” is significant to eliminate the very high-energy spread and understand the importance of chirping the laser pulse frequency. We intend to publish the results of the mixing process in 2-D. We intend to publish Chirp-induced transparency. More information can be found in the document.« less

X-ray Heating and Electron Temperature of Laboratory Photoionized Plasmas

NASA Astrophysics Data System (ADS)

Mancini, Roberto; Lockard, Tom; Mayes, Daniel C.; Loisel, Guillaume; Bailey, James E.; Rochau, Gregory; Abdallah, J.; Golovkin, I.

2018-06-01

In separate experiments performed at the Z facility of Sandia National Laboratories two different samples were employed to produce and characterize photoionized plasmas. One was a gas cell filled with neon, and the other was a thin silicon layer coated with plastic. Both samples were driven by the broadband x-ray flux produced at the collapse of a wire array z-pinch implosion. Transmission spectroscopy of a narrowband portion of the x-ray flux was used to diagnose the charge state distribution, and the electron temperature was extracted from a Li-like ion level population ratio. To interpret the temperature measurement, we performed Boltzmann kinetics and radiation-hydrodynamic simulations. We found that non-equilibrium atomic physics and the coupling of the radiation flux to the atomic level population kinetics play a critical role in modeling the x-ray heating of photoionized plasmas. In spite of being driven by similar x-ray drives, differences of ionization and charged state distributions in the neon and silicon plasmas are reflected in the plasma heating and observed electron temperatures.This work was sponsored in part by DOE Office of Science Grant DE-SC0014451, and the Z Facility Fundamental Science Program of SNL.

The interaction of the near-field plasma with antennas used in magnetic fusion research

NASA Astrophysics Data System (ADS)

Caughman, John

2015-09-01

Plasma heating and current drive using antennas in the Ion Cyclotron Range of Frequencies (ICRF) are important elements for the success of magnetic fusion. The antennas must operate in a harsh environment, where local plasma densities can be >1018/m3, magnetic fields can range from 0.2-5 Tesla, and antenna operating voltages can be >40 kV. This environment creates operational issues due to the interaction of the near-field of the antenna with the local plasma. In addition to parasitic losses in this plasma region, voltage and current distributions on the antenna structure lead to the formation of high electric fields and RF plasma sheaths, which can lead to enhanced particle and energy fluxes on the antenna and on surfaces intersected by magnetic field lines connected to or passing near the antenna. These issues are being studied using a simple electrode structure and a single-strap antenna on the Prototype Materials Plasma EXperiment (Proto-MPEX) at ORNL, which is a linear plasma device that uses an electron Bernstein wave heated helicon plasma source to create a high-density plasma suitable for use in a plasma-material interaction test stand. Several diagnostics are being used to characterize the near-field interactions, including double-Langmuir probes, a retarding field energy analyzer, and optical emission spectroscopy. The RF electric field is being studied utilizing Dynamic Stark Effect spectroscopy and Doppler-Free Saturation Spectroscopy. Recent experimental results and future plans will be presented. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract DE-AC-05-00OR22725.

Plasmakristall-4: New complex (dusty) plasma laboratory on board the International Space Station

NASA Astrophysics Data System (ADS)

Pustylnik, M. Y.; Fink, M. A.; Nosenko, V.; Antonova, T.; Hagl, T.; Thomas, H. M.; Zobnin, A. V.; Lipaev, A. M.; Usachev, A. D.; Molotkov, V. I.; Petrov, O. F.; Fortov, V. E.; Rau, C.; Deysenroth, C.; Albrecht, S.; Kretschmer, M.; Thoma, M. H.; Morfill, G. E.; Seurig, R.; Stettner, A.; Alyamovskaya, V. A.; Orr, A.; Kufner, E.; Lavrenko, E. G.; Padalka, G. I.; Serova, E. O.; Samokutyayev, A. M.; Christoforetti, S.

2016-09-01

New complex-plasma facility, Plasmakristall-4 (PK-4), has been recently commissioned on board the International Space Station. In complex plasmas, the subsystem of μm-sized microparticles immersed in low-pressure weakly ionized gas-discharge plasmas becomes strongly coupled due to the high (103-104 e) electric charge on the microparticle surface. The microparticle subsystem of complex plasmas is available for the observation at the kinetic level, which makes complex plasmas appropriate for particle-resolved modeling of classical condensed matter phenomena. The main purpose of PK-4 is the investigation of flowing complex plasmas. To generate plasma, PK-4 makes use of a classical dc discharge in a glass tube, whose polarity can be switched with the frequency of the order of 100 Hz. This frequency is high enough not to be felt by the relatively heavy microparticles. The duty cycle of the polarity switching can be also varied allowing to vary the drift velocity of the microparticles and (when necessary) to trap them. The facility is equipped with two videocameras and illumination laser for the microparticle imaging, kaleidoscopic plasma glow observation system and minispectrometer for plasma diagnostics and various microparticle manipulation devices (e.g., powerful manipulation laser). Scientific experiments are programmed in the form of scripts written with the help of specially developed C scripting language libraries. PK-4 is mainly operated from the ground (control center CADMOS in Toulouse, France) with the support of the space station crew. Data recorded during the experiments are later on delivered to the ground on the removable hard disk drives and distributed to participating scientists for the detailed analysis.

Plasmakristall-4: New complex (dusty) plasma laboratory on board the International Space Station.

PubMed

Pustylnik, M Y; Fink, M A; Nosenko, V; Antonova, T; Hagl, T; Thomas, H M; Zobnin, A V; Lipaev, A M; Usachev, A D; Molotkov, V I; Petrov, O F; Fortov, V E; Rau, C; Deysenroth, C; Albrecht, S; Kretschmer, M; Thoma, M H; Morfill, G E; Seurig, R; Stettner, A; Alyamovskaya, V A; Orr, A; Kufner, E; Lavrenko, E G; Padalka, G I; Serova, E O; Samokutyayev, A M; Christoforetti, S

2016-09-01

New complex-plasma facility, Plasmakristall-4 (PK-4), has been recently commissioned on board the International Space Station. In complex plasmas, the subsystem of μm-sized microparticles immersed in low-pressure weakly ionized gas-discharge plasmas becomes strongly coupled due to the high (10 3 -10 4 e) electric charge on the microparticle surface. The microparticle subsystem of complex plasmas is available for the observation at the kinetic level, which makes complex plasmas appropriate for particle-resolved modeling of classical condensed matter phenomena. The main purpose of PK-4 is the investigation of flowing complex plasmas. To generate plasma, PK-4 makes use of a classical dc discharge in a glass tube, whose polarity can be switched with the frequency of the order of 100 Hz. This frequency is high enough not to be felt by the relatively heavy microparticles. The duty cycle of the polarity switching can be also varied allowing to vary the drift velocity of the microparticles and (when necessary) to trap them. The facility is equipped with two videocameras and illumination laser for the microparticle imaging, kaleidoscopic plasma glow observation system and minispectrometer for plasma diagnostics and various microparticle manipulation devices (e.g., powerful manipulation laser). Scientific experiments are programmed in the form of scripts written with the help of specially developed C scripting language libraries. PK-4 is mainly operated from the ground (control center CADMOS in Toulouse, France) with the support of the space station crew. Data recorded during the experiments are later on delivered to the ground on the removable hard disk drives and distributed to participating scientists for the detailed analysis.

Experimental Measurement of the Nonlinear Interaction between Counterpropagating Alfv'en Waves in the LaPD

NASA Astrophysics Data System (ADS)

Schroeder, J. W. R.; Drake, D. J.; Howes, G. G.; Skiff, F.; Kletzing, C. A.; Carter, T. A.; Dorfman, S.; Auerbach, D.

2012-10-01

Turbulence plays an important role in the transport of mass and energy in many space and astrophysical plasmas ranging from galaxy clusters to Earth's magnetosphere. One active topic of research is the application of idealized Alfv'enic turbulence models to plasma conditions relevant to space and astrophysical plasmas. Alfv'enic turbulence models based on incompressible magnetohydrodynamics (MHD) contain a nonlinear interaction that drives the cascade of energy to smaller scales. We describe experiments at the Large Plasma Device (LaPD) that focus on the interaction of an Alfv'en wave traveling parallel to the mean magnetic field with a counterpropagating Alfv'en wave. Theory predicts the nonlinear interaction of the two primary waves will produce a secondary daughter Alfv'en wave. In this study, we present the first experimental identification of the daughter wave generated by nonlinear interactions between the primary Alfv'en waves.

Acceleration of electrons in strong beam-plasma interactions

NASA Technical Reports Server (NTRS)

Wilhelm, K.; Bernstein, W.; Kellogg, P. J.; Whalen, B. A.

1984-01-01

The effects of strong beam-plasma interactions on the electron population of the upper atmosphere have been investigated in an electron acceleration experiment performed with a sounding rocket. The rocket carried the Several Complex Experiments (SCEX) payload which included an electron accelerator, three disposable 'throwaway' detectors (TADs), and a stepped electron energy analyzer. The payload was launched in an auroral arc over the rocket at altitudes of 157 and 178 km, respectively. The performance characteristics of the instruments are discussed in detail. The data are combined with the results of laboratory measurements and show that electrons with energies of at least two and probably four times the injection energy of 2 keV were observed during strong beam-plasma interaction events. The interaction events occurred at pitch angles of 54 and 126 degrees. On the basis of the data it is proposed that the superenergization of the electrons is correlated with the length of the beam-plasma interaction region.

Laser-driven two-electron quantum dot in plasmas

NASA Astrophysics Data System (ADS)

Bahar, M. K.; Soylu, A.

2018-06-01

We have investigated the energies of two-electron parabolic quantum dots (TEPQdots) embedded in plasmas characterized by more general exponential cosine screened Coulomb (MGECSC) potential under the action of a monochromatic, linearly polarized laser field by solving the corresponding Schrödinger equation numerically via the asymptotic iteration method. The four different cases of the MGECSC potential constituted by various sets of the potential parameters are reckoned in modeling of the interactions in the plasma environments which are Debye and quantum plasmas. The plasma environment is a remarkable experimental argument for the quantum dots and the interactions in plasma environments are different compared to the interactions in an environment without plasma and the screening specifications of the plasmas can be controlled through the plasma parameters. These findings constitute our major motivation in consideration of the plasma environments. An appreciable confinement effect is made up by implementing the laser field on the TEPQdot. The influences of the laser field on the system are included by using the Ehlotzky approximation, and then Kramers-Henneberger transformation is carried out for the corresponding Schrödinger equation. The influences of the ponderomotive force on two-electron quantum dots embedded in plasmas are investigated. The behaviours, the similarities and the functionalities of the laser field, the plasma environment, and the quantum dot confinement are also scrutinized. In addition, the role of the plasma environments in the mentioned analysis is also discussed in detail.

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Formation of a plasma jet of multiply charged ions in the interaction of a laser plasma with an external pulsed magnetic field

NASA Astrophysics Data System (ADS)

Dyakin, V. M.; Pikuz, T. A.; Skobelev, I. Yu; Faenov, A. Ya; Wolowski, J.; Karpinski, L.; Kasperczuk, A.; Pisarczyk, T.

1994-12-01

A dense jet of a plasma consisting of multiply charged ions was generated in the interaction of a laser plasma with a strong external axial magnetic field. Images were formed by spectral lines and the soft x-ray spectrum range of the plasma jet was obtained with a large-aperture spectrograph containing a mica crystal bent to form a spherical surface with a radius of R = 10 cm. A tenfold increase in the density of the He-like Mg XI plasma, compared with a freely expanding plasma, was observed at a distance of 5 mm from the target.

X-ray Emission from the Interaction of a Macroscopic Particle with a Dense Plasma Focus.

DTIC Science & Technology

1976-10-01

Recently the interest in dense plasma focus has greatly increased because of the possibility of developing the device into an intense, pulsed...using a macroscopic particle to interact with a plasma focus . A theoretical study was carried out to predict the relative amount of X-ray increase

Report on final recommendations for IMPS engineering-science payload

NASA Technical Reports Server (NTRS)

Garrett, H. B.

1984-01-01

Six general categories of key scientific and engineering concerns for the interactions measurements payload for shuttle (IMPS) mission are addressed: (1) dielectric charging; (2) material property changes; (3) electromagnetic interference, plasma interactions, and plasma wake effects associated with high-voltage solar arrays and large space structures; (4) radio frequency distortion and nonlinearities due to the enhanced plasma in the shuttle ram/wake; (5) shuttle glow and contamination; and (6) plasma interactions with the space-based radar. Lesser concerns are the interactions associated with EVA; the radiation and SEU effects peculiar to the auroral/polar cap environments; and space debris. The measurements needed to address the concerns associated with the general categories are described and a list of generic investigations capable of making the required measurements, emphasizing the spectrum of measurements necessary to quantize the interactions in the auroral/polar environments are included. A suggested ground-test plan for the IMPS project, a description of proposed follow-on IMPS missions, and a detailed bibliography for each of the interactions discussed are included.

Transient effects in beam-plasma interactions in a space simulation chamber stimulated by a fast pulse electron gun

NASA Technical Reports Server (NTRS)

Raitt, W. J.; Banks, P. M.; Denig, W. F.; Anderson, H. R.

1982-01-01

Interest in the interaction of electron beams with plasma generated by ionization caused by the primary electron beam was stimulated by the need to develop special vacuum tubes to operate in the kMHz frequency region. The experiments of Getty and Smullin (1963) indicated that the interaction of an energetic electron beam with its self-produced plasma resulted in the emission of wave energy over a wide range of frequencies associated with cyclotron and longitudinal plasma instabilities. This enhanced the thermal plasma density in the vicinity of the beam, and the term Beam-Plasma Discharge (BPD) was employed to described this phenomenon. The present investigation is concerned with some of the transient phenomena associated with wave emission during the beam switch-on and switch-off periods. Results are presented on the changes in electron energy spectra on a time scale of tens of milliseconds following beam switch-on. The results are discussed in terms of the beam plasma discharge phenomenon.

Plasma Jet Interaction with Thomson Scattering Probe Laser

NASA Astrophysics Data System (ADS)

Byvank, Tom; Banasek, Jacob; Potter, William; Kusse, Bruce

2016-10-01

Thomson scattering systems can diagnose plasma temperatures and velocities. When probing a plasma jet with the Thomson scattering laser, we observe a laser-plasma interaction that inputs energy into the plasma jet. The absorbed energy causes a bubble of low density ( 5*1017 cm-2) in the jet (unperturbed 1018 cm-2). A pulsed power machine (1 MA peak current, 100 ns rise time) with a radial foil (15 μm thick Al) configuration generates the plasma jet. We compare the effects of using 10 J and 1 J laser energies, for which the 10 J laser is a larger perturbation. We discuss how the interaction affects the Thomson scattering temperature and velocity measurements. Work supported by National Nuclear Security Administration (NNSA) Stewardship Sciences Academic Programs under Department of Energy (DOE) Cooperative Agreement DE-NA0001836 and National Science Foundation (NSF) Grant PHY-1102471.

Innovative potential of plasma technology

NASA Astrophysics Data System (ADS)

Budaev, V. P.

2017-11-01

The review summarizes recent experimental observations of materials exposed to extreme hot plasma loads in fusion devices and plasma facilities with high-temperature plasma. Plasma load on the material in such devices lead to the stochastic clustering and fractal growth of the surface on scales from tens of nanometers to hundreds of micrometers forming statistical self-similarity of the surface roughness with extremely high specific area. Statistical characteristics of hierarchical granularity and scale invariance of such materials surface qualitatively differ from the properties of the roughness of the ordinary Brownian surface which provides a potential of innovative plasma technologies for synthesis of new nanostructured materials with programmed roughness properties, for hypersonic technologies, for biotechnology and biomedical applications.

MHD Simulations of Magnetospheric Accretion, Ejection and Plasma-field Interaction

NASA Astrophysics Data System (ADS)

Romanova, M. M.; Lovelace, R. V. E.; Bachetti, M.; Blinova, A. A.; Koldoba, A. V.; Kurosawa, R.; Lii, P. S.; Ustyugova, G. V.

2014-01-01

We review recent axisymmetric and three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetospheric accretion, plasma-field interaction and outflows from the disk-magnetosphere boundary.

Non-linear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.-M.; Crawford, F. W.

1979-01-01

Non-linear three-wave interaction is analysed for propagation along a cylindrical plasma column surrounded by an infinite dielectric, in the absence of a static magnetic field. An averaged-Lagrangian method is used, and the results are specialized to parametric interaction and mode conversion, assuming an undepleted pump wave. The theory for these two types of interactions is extended to include imperfect synchronism, and the effects of loss. Computations are presented indicating that parametric growth rates of the order of a fraction of a decibel per centimeter should be obtainable for plausible laboratory plasma column parameters.

Comparisons of social interaction and activities of daily living between long-term care facility and community-dwelling stroke patients.

PubMed

Yoon, Jeong-Ae; Park, Se-Gwan; Roh, Hyo-Lyun

2015-10-01

[Purpose] This study was conducted to compare the correlation between social interaction and activities of daily living (ADL) between community-dwelling and long-term care facility stroke patients. [Subjects and Methods] The Subjects were 65 chronic stroke patients (32 facility-residing, 33 community-dwelling). The Evaluation Social Interaction (ESI) tool was used to evaluate social interaction and the Assessment of Motor and Process Skills (AMPS) measure was used to evaluate ADL. [Results] Both social interaction and ADL were higher in community-dwelling than facility-residing stroke patients. There was a correlation between ESI and ADL for both motor and process skills among facility-residing patients, while only ADL process skills and ESI correlated among community-dwelling patients. In a partial correlation analysis using ADL motor and process skills as control variables, only process skills correlated with ESI. [Conclusion] For rehabilitation of stroke patients, an extended treatment process that combines ADL and social activities is likely to be required. Furthermore, treatment programs and institutional systems that can improve social interaction and promote health maintenance for community-dwelling and facility-residing chronic stroke patients are needed throughout the rehabilitation process.

Impact of Pre-Plasma on Electron Generation and Transport in Laser Plasma Interactions

NASA Astrophysics Data System (ADS)

Peebles, Jonathan Lee

Relativistic laser plasma interactions in conjunction with an underdense pre-plasma have been shown to generate a two temperature component electron spectrum. The lower temperature component described by "ponderomotive scaling'" is relatively well known and understood and is useful for applications such as the fast ignition inertial confinement fusion scheme. The higher energy electrons generated due to pre-plasma are denoted as "super-ponderomotive" electrons and facilitate interesting and useful applications. These include but are not limited to table top particle acceleration and generating high energy protons, x-rays and neutrons from secondary interactions. This dissertation describes experimental and particle-in-cell computational studies of the electron spectra produced from interactions between short pulse high intensity lasers and controlled pre-plasma conditions. Experiments were conducted at 3 laser labs: Texas Petawatt (University of Texas at Austin), Titan (Lawrence Livermore National Laboratory) and OMEGA-EP (University of Rochester). These lasers have different capabilities, and multiple experiments were carried out in order to fully understand super-ponderomotive electron generation and transport in the high intensity laser regime (I > 1018 W/cm2). In these experiments, an additional secondary long pulse beam was used to generate different scale lengths of "injected" pre-plasma while the pulse length and intensity of the short pulse beam were varied. The temperature and quantity of super-ponderomotive electrons were monitored with magnetic spectrometers and inferred via bremsstrahlung spectrometers while trajectory was estimated via Cu-Kalpha imaging. The experimental and simulation data show that super-ponderomotive electrons require pulse lengths of at least 450 fs to be accelerated and that higher intensity interactions generate large magnetic fields which cause severe deflection of the super-ponderomotive electrons. Laser incidence angle is shown to be extremely important in determining hot electron trajectory. Longer pulse length data taken on OMEGA-EP and Titan showed that super-ponderomotive electrons could be created without the need for an initial pre-plasma due to the underdense plasma created during the high intensity interaction alone.

The interaction between Saturn's moons and their plasma environments

NASA Astrophysics Data System (ADS)

Simon, Sven; Roussos, Elias; Paty, Carol S.

2015-11-01

Since the arrival of the Cassini spacecraft at Saturn in July 2004, newly collected plasma and magnetic field data have greatly expanded our knowledge on the interaction between the giant planet's multifaceted family of moons and its magnetospheric environment. Cassini has already accomplished more than 200 orbits around Saturn, encompassing 111 flybys of the giant planet's largest moon Titan and 20 encounters of Enceladus. This small icy moon had been identified as the major source of magnetospheric plasma and neutral particles during the first year of Cassini's tour in the Saturnian system. In addition, the spacecraft has paid visits to several other icy satellites in the inner and middle magnetosphere: Rhea, Dione and Tethys. Depending on the ambient magnetospheric flow parameters as well as the properties of its atmosphere/ionosphere and surface, each of these moons generates a characteristic and unique set of perturbation signatures in the magnetospheric plasma incident upon it. Therefore, observations made during close flybys of Saturn's moons by the Cassini plasma and magnetic field detectors contain valuable diagnostic information on the properties of the moons' atmospheres, surfaces and even their interiors. However, the spacecraft can measure these plasma and magnetic field perturbations only along its trajectory, whereas the interaction between the moons and their plasma environments constitutes a complex three-dimensional process. Therefore, sophisticated models are required in order to place the data collected along Cassini's flyby trajectories within the context of the full three-dimensional moon-plasma interaction scenarios. In this review, we combine observations from the Cassini mission with sophisticated modeling results to draw a comprehensive picture of the interaction between Saturn's largest moons and their highly dynamic plasma environments.

Comparison the Results of Numerical Simulation And Experimental Results for Amirkabir Plasma Focus Facility

NASA Astrophysics Data System (ADS)

Goudarzi, Shervin; Amrollahi, R.; Niknam Sharak, M.

2014-06-01

In this paper the results of the numerical simulation for Amirkabir Mather-type Plasma Focus Facility (16 kV, 36μF and 115 nH) in several experiments with Argon as working gas at different working conditions (different discharge voltages and gas pressures) have been presented and compared with the experimental results. Two different models have been used for simulation: five-phase model of Lee and lumped parameter model of Gonzalez. It is seen that the results (optimum pressures and current signals) of the Lee model at different working conditions show better agreement than lumped parameter model with experimental values.

Large ionospheric disturbances produced by the HAARP HF facility

NASA Astrophysics Data System (ADS)

Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; McCarrick, Mike; Michell, Robert G.

2016-07-01

The enormous transmitter power, fully programmable antenna array, and agile frequency generation of the High Frequency Active Auroral Research Program (HAARP) facility in Alaska have allowed the production of unprecedented disturbances in the ionosphere. Using both pencil beams and conical (or twisted) beam transmissions, artificial ionization clouds have been generated near the second, third, fourth, and sixth harmonics of the electron gyrofrequency. The conical beam has been used to sustain these clouds for up to 5 h as opposed to less than 30 min durations produced using pencil beams. The largest density plasma clouds have been produced at the highest harmonic transmissions. Satellite radio transmissions at 253 MHz from the National Research Laboratory TACSat4 communications experiment have been severely disturbed by propagating through artificial plasma regions. The scintillation levels for UHF waves passing through artificial ionization clouds from HAARP are typically 16 dB. This is much larger than previously reported scintillations at other HF facilities which have been limited to 3 dB or less. The goals of future HAARP experiments should be to build on these discoveries to sustain plasma densities larger than that of the background ionosphere for use as ionospheric reflectors of radio signals.

From the Telescope to the Laboratory and Back Again: The Center for Astrophysical Plasma Properties

NASA Astrophysics Data System (ADS)

Houston Montgomery, Michael; Winget, Don; Schaeuble, Marc; Hawkins, Keith; Wheeler, Craig

2018-01-01

The Center for Astrophysical Plasma Properties (CAPP) is a new center focusing on the spectroscopic properties of stars and accretion disks using “at-parameter” experiments. Currently, these experiments use the X-ray output of the Z machine at Sandia National Laboratories—the largest X-ray source in the world—to heat plasmas to the same conditions (temperature, density, and radiation environment) as those observed in astronomical objects. Current experiments include measuring (1) density-dependent opacities of iron-peak elements at solar interior conditions, (2) spectral lines of low-Z elements at white dwarf photospheric conditions, (3) atomic population kinetics of neon in a radiation-dominated environment, and (4) resonant Auger destruction (RAD) of silicon at accretion disk conditions around supermassive black holes. We will be moving to new astrophysical environments and additional experimental facilities, such as the National Ignition Facility (NIF) and the OMEGA facility at the Laboratory for Laser Energetics (LLE). We seek students and collaborators to work on these experiments as well as the calculations that complement them. CAPP has funding for 5 years and can support up to six graduate students and three post-docs.

Final Report of “Collaborative research: Fundamental science of low temperature plasma-biological material interactions” (Award# DE-SC0005105)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oehrlein, Gottlieb S.; Seog, Joonil; Graves, David

2014-09-24

Low temperature plasma (LTP) treatment of biological tissue is a promising path toward sterilization of bacteria due to its versatility and ability to operate under well-controlled and relatively mild conditions. The present collaborative research of an interdisciplinary team of investigators at University of Maryland, College Park (UMD), and University of California, Berkeley (UCB) focused on establishing our knowledge on low temperature plasma-induced chemical modifications in biomolecules that result in inactivation due to various plasma species, including ions, reactive radicals, and UV/VUV photons. The overall goals of the project were to identify the mechanisms by which low and atmospheric pressure plasmamore » (APP) deactivates endotoxic biomolecules. Additionally, we wanted to understand how deactivation processes depend on the interaction of APP with the environment. Various low pressure plasma sources, a vacuum beam system and several atmospheric pressure plasma sources were used to accomplish these objectives. In our work we elucidated for the first time the role of ions, VUV photons and radicals in biological deactivation of model endotoxic biomolecules, both in a UHV beam system and an inductively coupled, low pressure plasma system, and established the associated atomistic modifications in biomolecules. While we showed that both ions and VUV photons can be very efficient in deactivation of biomolecules, significant etching and/or deep modification (~200 nm) were accompanied by these biological effects. One of the most important findings in this work is that the significant deactivation and surface modification can occur with minimal etching using radical species. However, if radical fluxes and corresponding etch rates are relatively high, for example, at atmospheric pressure, inactivation of endotoxic biomolecule film may require near-complete removal of the film. These findings motivated further work at atmospheric pressure using several types of low temperature plasma sources with modified geometry where radical induced interactions generally dominate due to short mean free paths of ions and VUV photons. In these conditions we demonstrated the importance of environmental interactions of plasma species when APP sources are used to modify biomolecules. This is evident from both gas phase characterization data and in-situ surface characterization of treated biomolecules. Environmental interactions can produce unexpected outcomes due to the complex reactions of reactive species with the atmosphere which determine the composition of reactive fluxes and atomistic changes in biomolecules. Overall, this work elucidated a richer spectrum of scientific opportunities and challenges for the field of low temperature plasma-biomolecule surface interactions than initially anticipated, in particular, for plasma sources operating at atmospheric pressure. The insights produced in this work, e.g. demonstration of the importance of environmental interactions, are generally important for applications of APP to materials modifications. Thus one major contributions of this research has been the establishment of methodologies to study the interaction of plasma with bio-molecules in a systemic and rigorous manner. In particular, our studies of atmospheric pressure plasma sources using very well-defined experimental conditions enabled us to correlate atomistic surface modifications of biomolecules with changes in their biological function. The clarification of the role of ions, VUV photons and radicals in deactivation of biomolecules during low pressure and atmospheric pressure plasma-biomolecule interaction has broad implications, e.g. for the emerging field of plasma medicine. The development of methods to detect the effects of plasma treatment on immune-active biomolecules will lay a fundamental foundation to enhance our understanding of the effect of plasma on biological systems. be helpful in many future studies.« less

Ionic protein-lipid interaction at the plasma membrane: what can the charge do?

PubMed

Li, Lunyi; Shi, Xiaoshan; Guo, Xingdong; Li, Hua; Xu, Chenqi

2014-03-01

Phospholipids are the major components of cell membranes, but they have functional roles beyond forming lipid bilayers. In particular, acidic phospholipids form microdomains in the plasma membrane and can ionically interact with proteins via polybasic sequences, which can have functional consequences for the protein. The list of proteins regulated by ionic protein-lipid interaction has been quickly expanding, and now includes membrane proteins, cytoplasmic soluble proteins, and viral proteins. Here we review how acidic phospholipids in the plasma membrane regulate protein structure and function via ionic interactions, and how Ca(2+) regulates ionic protein-lipid interactions via direct and indirect mechanisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Laboratory plasma interactions experiments: Results and implications to future space systems

NASA Technical Reports Server (NTRS)

Leung, Philip

1986-01-01

The experimental results discussed show the significance of the effects caused by spacecraft plasma interactions, in particular the generation of Electromagnetic Interference. As the experimental results show, the magnitude of the adverse effects induced by Plasma Interactions (PI) will be more significant for spacecraft of the next century. Therefore, research is needed to control possible adverse effects. Several techniques to control the selected PI effects are discussed. Tests, in the form of flight experiments, are needed to validate these proposed ideas.

Interaction of high-intensity laser radiation with metals.

NASA Technical Reports Server (NTRS)

Linlor, W. I.

1971-01-01

The interaction is characterized by the production of plasma, within which the primary absorption occurs. Absorption of laser radiation by a plasma may occur by several processes. The absorption process called 'inverse bremsstrahlung' is discussed. The interaction of a laser beam with the plasma produced from a thick metal target was studied. The results of the measurements of the ion kinetic energies are presented in a graph. In addition to measurements with thick targets, information was also obtained with a thin foil of gold.

Plasma Lens for Muon and Neutrino Beams

NASA Astrophysics Data System (ADS)

Kahn, Stephen; Korenev, Sergey; Bishai, Mary; Diwan, Milind; Gallardo, Juan; Hershcovitch, Ady; Johnson, Brant

2008-04-01

The plasma lens is examined as an alternate to focusing horns and solenoids for use in a neutrino or muon beam facility. The plasma lens concept is based on a combined high-current lens/target configuration. The current is fed at electrodes located upstream and downstream from the target where pion capturing is needed. The current flows primarily in the plasma, which has a lower resistivity than the target. A second plasma lens section, with an additional current feed, follows the target to provide shaping of the plasma stability. The geometry of the plasma is shaped to provide optimal pion capture. Simulations of this plasma lens system have shown a 25% higher neutrino production than the horn system. A plasma lens has additional advantage: larger axial current than horns, minimal neutrino contamination during antineutrino running, and negligible pion absorption or scattering. Results from particle simulations using a plasma lens will be presented.

Proton pinhole imaging on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Zylstra, A. B.; Park, H.-S.; Ross, J. S.; Fiuza, F.; Frenje, J. A.; Higginson, D. P.; Huntington, C.; Li, C. K.; Petrasso, R. D.; Pollock, B.; Remington, B.; Rinderknecht, H. G.; Ryutov, D.; Séguin, F. H.; Turnbull, D.; Wilks, S. C.

2016-11-01

Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.

Diagnosing laser-preheated magnetized plasmas relevant to magnetized liner inertial fusion

DOE PAGES

Harvey-Thompson, Adam James; Sefkow, Adam B.; Nagayama, Taisuke N.; ...

2015-12-22

In this paper, we present a platform on the OMEGA EP Laser Facility that creates and diagnoses the conditions present during the preheat stage of the MAGnetized Liner Inertial Fusion (MagLIF) concept. Experiments were conducted using 9 kJ of 3ω (355 nm) light to heat an underdense deuterium gas (electron density: 2.5 × 10 20 cm -3 = 0.025 of critical density) magnetized with a 10 T axial field. Results show that the deuterium plasma reached a peak electron temperature of 670 ± 140 eV, diagnosed using streaked spectroscopy of an argon dopant. The results demonstrate that plasmas relevant tomore » the preheat stage of MagLIF can be produced at multiple laser facilities, thereby enabling more rapid progress in understanding magnetized preheat. Results are compared with magneto-radiation-hydrodynamics simulations, and plans for future experiments are described.« less

Proton pinhole imaging on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zylstra, Alex B.; Park, H. -S.; Ross, J. S.

Here, pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. Whenmore » the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.« less

Proton pinhole imaging on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zylstra, A. B., E-mail: zylstra@lanl.gov; Park, H.-S.; Ross, J. S.

Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. Whenmore » the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.« less

Proton pinhole imaging on the National Ignition Facility

DOE PAGES

Zylstra, Alex B.; Park, H. -S.; Ross, J. S.; ...

2016-07-29

Here, pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. Whenmore » the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.« less

Study of soft X-ray emission during wire array implosion under plasma focus conditions at the PF-3 facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dan’ko, S. A.; Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Krauz, V. I.

2015-11-15

Results of measurements of soft X-ray emission with photon energies of <1 keV under conditions of a plasma focus (PF) experiment are presented. The experiments were carried out at the world’s largest PF device—the PF-3 Filippov-type facility (I ⩽ 3 MA, T/4 ≈ 15–20 µs, W{sub 0} ⩽ 3 MJ). X-ray emission from both a discharge in pure neon and with a tungsten wire array placed on the axis of the discharge chamber was detected. The wire array imploded under the action of the electric current intercepted from the plasma current sheath of the PF discharge in neon. The measuredmore » soft X-ray powers from a conventional PF discharge in gas and a PF discharge in the presence of a wire array were compared for the first time.« less

Status and Plans for the FLARE (Facility for Laboratory Reconnection Experiments) Project

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W.; Bale, S.; Carter, T.; Crocker, N.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.; Chen, Y.; Cutler, R.; Fox, W.; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.

2015-11-01

The FLARE device (flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton to study magnetic reconnection in regimes directly relevant to space, solar, astrophysical, and fusion plasmas. The existing small-scale experiments have been focusing on the single X-line reconnection process either with small effective sizes or at low Lundquist numbers, but both of which are typically very large in natural and fusion plasmas. The design of the FLARE device is motivated to provide experimental access to the new regimes involving multiple X-lines, as guided by a reconnection ``phase diagram'' [Ji & Daughton, PoP (2011)]. Most of major components of the FLARE device have been designed and are under construction. The device will be assembled and installed in 2016, followed by commissioning and operation in 2017. The planned research on FLARE as a user facility will be discussed. Supported by NSF.

Proton pinhole imaging on the National Ignition Facility.

PubMed

Zylstra, A B; Park, H-S; Ross, J S; Fiuza, F; Frenje, J A; Higginson, D P; Huntington, C; Li, C K; Petrasso, R D; Pollock, B; Remington, B; Rinderknecht, H G; Ryutov, D; Séguin, F H; Turnbull, D; Wilks, S C

2016-11-01

Pinhole imaging of large (mm scale) carbon-deuterium (CD) plasmas by proton self-emission has been used for the first time to study the microphysics of shock formation, which is of astrophysical relevance. The 3 MeV deuterium-deuterium (DD) fusion proton self-emission from these plasmas is imaged using a novel pinhole imaging system, with up to five different 1 mm diameter pinholes positioned 25 cm from target-chamber center. CR39 is used as the detector medium, positioned at 100 cm distance from the pinhole for a magnification of 4 ×. A Wiener deconvolution algorithm is numerically demonstrated and used to interpret the images. When the spatial morphology is known, this algorithm accurately reproduces the size of features larger than about half the pinhole diameter. For these astrophysical plasma experiments on the National Ignition Facility, this provides a strong constraint on simulation modeling of the experiment.

Characterization of Bufo arenarum oocyte plasma membrane proteins that interact with sperm.

PubMed

Coux, Gabriela; Cabada, Marcelo O

2006-04-28

Sperm-oocyte plasma membrane interaction is an essential step in fertilization. In amphibians, the molecules involved have not been identified. Our aim was to detect and characterize oocyte molecules with binding affinity for sperm. We isolated plasma membranes free from vitelline envelope and yolk proteins from surface-biotinylated Bufo arenarum oocytes. Using binding assays we detected a biotinylated 100 kDa plasma membrane protein that consistently bound to sperm. Chromatographic studies confirmed the 100 kDa protein and detected two additional oocyte molecules of 30 and 70 kDa with affinity for sperm. Competition studies with an integrin-interacting peptide and cross-reaction with an anti-HSP70 antibody suggested that the 100 and 70 kDa proteins are members of the integrin family and HSP70, respectively. MS/MS analysis suggested extra candidates for a role in this step of fertilization. In conclusion, we provide evidence for the involvement of several proteins, including integrins and HSP70, in B. arenarum sperm-oocyte plasma membrane interactions.

Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

NASA Astrophysics Data System (ADS)

Salehi, M.; Mirzanejad, S.

2017-05-01

Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

Simulations of the interaction of intense petawatt laser pulses with dense Z-pinch plasmas : final report LDRD 39670.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, Dale Robert; MacFarlane, Joseph John; Mehlhorn, Thomas Alan

We have studied the feasibility of using the 3D fully electromagnetic implicit hybrid particle code LSP (Large Scale Plasma) to study laser plasma interactions with dense, compressed plasmas like those created with Z, and which might be created with the planned ZR. We have determined that with the proper additional physics and numerical algorithms developed during the LDRD period, LSP was transformed into a unique platform for studying such interactions. Its uniqueness stems from its ability to consider realistic compressed densities and low initial target temperatures (if required), an ability that conventional PIC codes do not possess. Through several testmore » cases, validations, and applications to next generation machines described in this report, we have established the suitability of the code to look at fast ignition issues for ZR, as well as other high-density laser plasma interaction problems relevant to the HEDP program at Sandia (e.g. backlighting).« less

Plasma Interaction with International Space Station High Voltage Solar Arrays

NASA Technical Reports Server (NTRS)

Heard, John W.

2002-01-01

The International Space Station (ISS) is presently being assembled in low-earth orbit (LEO) operating high voltage solar arrays (-160 V max, -140 V typical with respect to the ambient atmosphere). At the station's present altitude, there exists substantial ambient plasma that can interact with the solar arrays. The biasing of an object to an electric potential immersed in plasma creates a plasma "sheath" or non-equilibrium plasma around the object to mask out the electric fields. A positively biased object can collect electrons from the plasma sheath and the sheath will draw a current from the surrounding plasma. This parasitic current can enter the solar cells and effectively "short out" the potential across the cells, reducing the power that can be generated by the panels. Predictions of collected current based on previous high voltage experiments (SAMPIE (Solar Array Module Plasma Interactions Experiment), PASP+ (Photovoltaic Array Space Power) were on the order of amperes of current. However, present measurements of parasitic current are on the order of several milliamperes, and the current collection mainly occurs during an "eclipse exit" event, i.e., when the space station comes out of darkness. This collection also has a time scale, t approx. 1000 s, that is much slower than any known plasma interaction time scales. The reason for the discrepancy between predictions and present electron collection is not understood and is under investigation by the PCU (Plasma Contactor Unit) "Tiger" team. This paper will examine the potential structure within and around the solar arrays, and the possible causes and reasons for the electron collection of the array.

Iodine Plasma (Electric Propulsion) Interaction with Spacecraft Materials

DTIC Science & Technology

2016-12-28

fairly resistant to the reactive iodine and iodine plasma . The tantalum heat shielding , though, does react with iodine. DISTRIBUTION A: Distribution...way coupling manner due to the disparate time scales between the electrons (10-10 s ) and plasma (10-3 s ).17,18 Exhaust particles were modeled in two... plasma iodine impacts/m2/ s . Figure 7: iSAT Plume Interaction4 The velocity of both the neutrals and ions impacting the surface will be relatively

Physical and biological mechanisms of nanosecond- and microsecond-pulsed FE-DBD plasma interaction with biological objects

NASA Astrophysics Data System (ADS)

Dobrynin, Danil

2013-09-01

Mechanisms of plasma interaction with living tissues and cells can be quite complex, owing to the complexity of both the plasma and the tissue. Thus, unification of all the mechanisms under one umbrella might not be possible. Here, analysis of interaction of floating electrode dielectric barrier discharge (FE-DBD) with living tissues and cells is presented and biological and physical mechanisms are discussed. In physical mechanisms, charged species are identified as the major contributors to the desired effect and a mechanism of this interaction is proposed. Biological mechanisms are also addressed and a hypothesis of plasma selectivity and its effects is offered. Spatially uniform nanosecond and sub-nanosecond short-pulsed dielectric barrier discharge plasmas are gaining popularity in biological and medical applications due to their increased uniformity, lower plasma temperature, lower surface power density, and higher concentration of the active species produced. In this presentation we will compare microsecond pulsed plasmas with nanosecond driven systems and their applications in biology and medicine with specific focus on wound healing and tissue regeneration. Transition from negative to positive streamer will be discussed with proposed hypothesis of uniformity mechanisms of positive streamer and the reduced dependence on morphology and surface chemistry of the second electrode (human body) being treated. Uniform plasma offers a more uniform delivery of active species to the tissue/surface being treated thus leading to better control over the biological results.

Current drive at plasma densities required for thermonuclear reactors.

PubMed

Cesario, R; Amicucci, L; Cardinali, A; Castaldo, C; Marinucci, M; Panaccione, L; Santini, F; Tudisco, O; Apicella, M L; Calabrò, G; Cianfarani, C; Frigione, D; Galli, A; Mazzitelli, G; Mazzotta, C; Pericoli, V; Schettini, G; Tuccillo, A A

2010-08-10

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.

Some Basic Concepts of Wave-Particle Interactions in Collisionless Plasmas

NASA Technical Reports Server (NTRS)

Lakhina, Gurbax S.; Tsurutani, Bruce T.

1997-01-01

The physical concepts of wave-particle interactions in a collisionless plasma are developed from first principles. Using the Lorentz force, starting with the concepts of gyromotion, particle mirroring and the loss-cone, normal and anomalous cyclotron resonant interactions, pitch-angle scattering, and cross-field diffusion are developed.

From core to coax: extending core RF modelling to include SOL, Antenna, and PFC

NASA Astrophysics Data System (ADS)

Shiraiwa, Syun'ichi

2017-10-01

A new technique for the calculation of RF waves in toroidal geometry enables the simultaneous incorporation of antenna geometry, plasma facing components (PFCs), the scrape off-layer (SOL), and core propagation. Traditionally, core RF wave propagation and antenna coupling has been calculated separately both using rather simplified SOL plasmas. The new approach, instead, allows capturing wave propagation in the SOL and its interactions with non-conforming PFCs permitting self-consistent calculation of core absorption and edge power loss, as well as investigating far and near field impurity generation from RF sheaths and a breakdown issue from antenna electric fields. Our approach combines the field solutions obtained from a core spectral code with a hot plasma dielectric and an edge FEM code using a cold plasma approximation via surface admittance-like matrix. Our approach was verified using the TORIC core ICRF spectral code and the commercial COMSOL FEM package, and was extended to 3D torus using open-source scalable MFEM library. The simulation result revealed that as the core wave damping gets weaker, the wave absorption in edge could become non-negligible. Three dimensional capabilities with non axisymmetric edge are being applied to study the antenna characteristic difference between the field aligned and toroidally aligned antennas on Alcator C-Mod, as well as the surface wave excitation on NSTX-U. Work supported by the U.S. DoE, OFES, using User Facility Alcator C-Mod, DE-FC02-99ER54512 and Contract No. DE-FC02-01ER54648.

Simulated performance of the optical Thomson scattering diagnostic designed for the National Ignition Facility

DOE PAGES

Ross, J. S.; Datte, P.; Divol, L.; ...

2016-07-28

An optical Thomson scattering diagnostic has been designed for the National Ignition Facility to characterize under-dense plasmas. Here, we report on the design of the system and the expected performance for different target configurations. The diagnostic is designed to spatially and temporally resolve the Thomson scattered light from laser driven targets. The diagnostic will collect scattered light from a 50 × 50 × 200 μm volume. The optical design allows operation with different probe laser wavelengths. A deep-UV probe beam (λ 0 = 210 nm) will be used to Thomson scatter from electron plasma densities of ~5 × 10 20more » cm -3 while a 3ω probe will be used for plasma densities of ~1 × 10 19 cm -3. The diagnostic package contains two spectrometers: the first to resolve Thomson scattering from ion acoustic wave fluctuations and the second to resolve scattering from electron plasma wave fluctuations. Expected signal levels relative to background will be presented for typical target configurations (hohlraums and a planar foil).« less

LETTER: Biased limiter experiments on the Advanced Toroidal Facility (ATF) torsatron

NASA Astrophysics Data System (ADS)

Uckan, T.; Isler, R. C.; Jernigan, T. C.; Lyon, J. F.; Mioduszewski, P. K.; Murakami, M.; Rasmussen, D. A.; Wilgen, J. B.; Aceto, S. C.; Zielinski, J. J.

1994-02-01

The Advanced Toroidal Facility (ATF) torsatron incorporates two rail limiters that can be positioned by external controls. The influence on the plasma parameters of biasing these limiters both positively and negatively with respect to the walls has been investigated. Experiments have been carried out in the electron cyclotron heated plasmas at 200 kW with a typical density of 5 × 1012 cm-3 and a central electron temperature of ~900 eV. Negative biasing produces only small changes in the plasma parameters, but positive biasing increases the particle confinement by about a factor of 5, although the plasma stored energy does fall at the higher voltages. In addition, positive biasing produces the following effects compared with floating limiter discharges: the core density profiles become peaked rather than hollow, the electric field at the edge becomes more negative (pointing radially inward), the magnitudes of the edge fluctuations and the fluctuation induced transport are reduced, the fluctuation wavelengths become longer and their propagation direction reverses from the electron to the ion diamagnetic direction. Neither polarity of biasing appears to affect the impurity content or transport

Simulated performance of the optical Thomson scattering diagnostic designed for the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, J. S., E-mail: ross36@llnl.gov; Datte, P.; Divol, L.

2016-11-15

An optical Thomson scattering diagnostic has been designed for the National Ignition Facility to characterize under-dense plasmas. We report on the design of the system and the expected performance for different target configurations. The diagnostic is designed to spatially and temporally resolve the Thomson scattered light from laser driven targets. The diagnostic will collect scattered light from a 50 × 50 × 200 μm volume. The optical design allows operation with different probe laser wavelengths. A deep-UV probe beam (λ{sub 0} = 210 nm) will be used to Thomson scatter from electron plasma densities of ∼5 × 10{sup 20} cm{supmore » −3} while a 3ω probe will be used for plasma densities of ∼1 × 10{sup 19} cm{sup −3}. The diagnostic package contains two spectrometers: the first to resolve Thomson scattering from ion acoustic wave fluctuations and the second to resolve scattering from electron plasma wave fluctuations. Expected signal levels relative to background will be presented for typical target configurations (hohlraums and a planar foil).« less

Electrical-thermal-structural finite element simulation and experimental study of a plasma ion source for the production of radioactive ion beams

NASA Astrophysics Data System (ADS)

Manzolaro, M.; Meneghetti, G.; Andrighetto, A.; Vivian, G.

2016-03-01

The production target and the ion source constitute the core of the selective production of exotic species (SPES) facility. In this complex experimental apparatus for the production of radioactive ion beams, a 40 MeV, 200 μA proton beam directly impinges a uranium carbide target, generating approximately 1013 fissions per second. The transfer line enables the unstable isotopes generated by the 238U fissions in the target to reach the ion source, where they can be ionized and finally accelerated to the subsequent areas of the facility. In this work, the plasma ion source currently adopted for the SPES facility is analyzed in detail by means of electrical, thermal, and structural numerical models. Next, theoretical results are compared with the electric potential difference, temperature, and displacement measurements. Experimental tests with stable ion beams are also presented and discussed.

Status of the FLARE (Facility for Laboratory Reconnection Experiments) Construction Project and Plans as a User Facility

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W.; Chen, Y.; Cutler, R.; Fox, W.; Hoffmann, F.; Kalish, M.; Jara-Almonte, J.; Myers, C.; Ren, Y.; Yamada, M.; Yoo, J.; Bale, S. D.; Carter, T.; Dorfman, S.; Drake, J.; Egedal, J.; Sarff, J.; Wallace, J.

2016-10-01

The FLARE device (flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton for the studies of magnetic reconnection in the multiple X-line regimes directly relevant to space, solar, astrophysical, and fusion plasmas, as guided by a reconnection phase diagram [Ji & Daughton, (2011)]. Most of major components either have been already fabricated or are near their completion, including the two most crucial magnets called flux cores. The hardware assembly and installation begin in this summer, followed by commissioning in 2017. Initial comprehensive set of research diagnostics will be constructed and installed also in 2017. The main diagnostics is an extensive set of magnetic probe arrays, covering multiple scales from local electron scales, to intermediate ion scales, and global MHD scales. The planned procedures and example topics as a user facility will be discussed.

Magnet Design Considerations for Fusion Nuclear Science Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Y.; Kessel, C.; El-Guebaly, L.

2016-06-01

The Fusion Nuclear Science Facility (FNSF) is a nuclear confinement facility that provides a fusion environment with components of the reactor integrated together to bridge the technical gaps of burning plasma and nuclear science between the International Thermonuclear Experimental Reactor (ITER) and the demonstration power plant (DEMO). Compared with ITER, the FNSF is smaller in size but generates much higher magnetic field, i.e., 30 times higher neutron fluence with three orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5more » T at the plasma center with a plasma major radius of 4.8 m and a minor radius of 1.2 m and a peak field of 15.5 T on the toroidal field (TF) coils for the FNSF. Both low-temperature superconductors (LTS) and high-temperature superconductors (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology. The higher magnetic field can be achieved by using the high-performance ternary restacked-rod process Nb3Sn strands for TF magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high-aspect-ratio rectangular CICC design are evaluated for FNSF magnets, but low-activation-jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. The material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.« less

Magnet design considerations for Fusion Nuclear Science Facility

DOE PAGES

Zhai, Yuhu; Kessel, Chuck; El-guebaly, Laila; ...

2016-02-25

The Fusion Nuclear Science Facility (FNSF) is a nuclear confinement facility to provide a fusion environment with components of the reactor integrated together to bridge the technical gaps of burning plasma and nuclear science between ITER and the demonstration power plant (DEMO). Compared to ITER, the FNSF is smaller in size but generates much higher magnetic field, 30 times higher neutron fluence with 3 orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5 T at the plasma center withmore » plasma major radius of 4.8 m and minor radius of 1.2 m, and a peak field of 15.5 T on the TF coils for FNSF. Both low temperature superconductor (LTS) and high temperature superconductor (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology. The higher magnetic field can be achieved by using the high performance ternary Restack Rod Process (RRP) Nb3Sn strands for toroidal field (TF) magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high aspect ratio rectangular CICC design are evaluated for FNSF magnets but low activation jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. As a result, the material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.« less

Observations of electron phase-space holes driven during magnetic reconnection in a laboratory plasma

NASA Astrophysics Data System (ADS)

Fox, W.; Porkolab, M.; Egedal, J.; Katz, N.; Le, A.

2012-03-01

This work presents detailed experimental observations of electron phase-space holes driven during magnetic reconnection events on the Versatile Toroidal Facility. The holes are observed to travel on the order of or faster than the electron thermal speed, and are of large size scale, with diameter of order 60 Debye lengths. In addition, they have 3D spheroidal structure with approximately unity aspect ratio. We estimate the direct anomalous resistivity due to ion interaction with the holes and find it to be too small to affect the reconnection rate; however, the holes may play a role in reining in a tail of accelerated electrons and they indicate the presence of other processes in the reconnection layer, such as electron energization and electron beam formation.

Mortality Benefit of Recombinant Human Interleukin-1 Receptor Antagonist for Sepsis Varies by Initial Interleukin-1 Receptor Antagonist Plasma Concentration.

PubMed

Meyer, Nuala J; Reilly, John P; Anderson, Brian J; Palakshappa, Jessica A; Jones, Tiffanie K; Dunn, Thomas G; Shashaty, Michael G S; Feng, Rui; Christie, Jason D; Opal, Steven M

2018-01-01

Plasma interleukin-1 beta may influence sepsis mortality, yet recombinant human interleukin-1 receptor antagonist did not reduce mortality in randomized trials. We tested for heterogeneity in the treatment effect of recombinant human interleukin-1 receptor antagonist by baseline plasma interleukin-1 beta or interleukin-1 receptor antagonist concentration. Retrospective subgroup analysis of randomized controlled trial. Multicenter North American and European clinical trial. Five hundred twenty-nine subjects with sepsis and hypotension or hypoperfusion, representing 59% of the original trial population. Random assignment of placebo or recombinant human interleukin-1 receptor antagonist × 72 hours. We measured prerandomization plasma interleukin-1 beta and interleukin-1 receptor antagonist and tested for statistical interaction between recombinant human interleukin-1 receptor antagonist treatment and baseline plasma interleukin-1 receptor antagonist or interleukin-1 beta concentration on 28-day mortality. There was significant heterogeneity in the effect of recombinant human interleukin-1 receptor antagonist treatment by plasma interleukin-1 receptor antagonist concentration whether plasma interleukin-1 receptor antagonist was divided into deciles (interaction p = 0.046) or dichotomized (interaction p = 0.028). Interaction remained present across different predicted mortality levels. Among subjects with baseline plasma interleukin-1 receptor antagonist above 2,071 pg/mL (n = 283), recombinant human interleukin-1 receptor antagonist therapy reduced adjusted mortality from 45.4% to 34.3% (adjusted risk difference, -0.12; 95% CI, -0.23 to -0.01), p = 0.044. Mortality in subjects with plasma interleukin-1 receptor antagonist below 2,071 pg/mL was not reduced by recombinant human interleukin-1 receptor antagonist (adjusted risk difference, +0.07; 95% CI, -0.04 to +0.17), p = 0.230. Interaction between plasma interleukin-1 beta concentration and recombinant human interleukin-1 receptor antagonist treatment was not statistically significant. We report a heterogeneous effect of recombinant human interleukin-1 receptor antagonist on 28-day sepsis mortality that is potentially predictable by plasma interleukin-1 receptor antagonist in one trial. A precision clinical trial of recombinant human interleukin-1 receptor antagonist targeted to septic patients with high plasma interleukin-1 receptor antagonist may be worthy of consideration.

Biasing experiments on the Advanced Toroidal Facility

NASA Astrophysics Data System (ADS)

Uckan, T.; Isler, R. C.; Jernigan, T. C.; Lyon, J. F.; Mioduszewski, P. K.; Murakami, M.; Rasmussen, D. A.; Wilgen, J. B.; Aceto, S. C.; Zielinski, J. J.

1992-09-01

Biasing experiments have been carried out in 1 T plasmas with approximately 200 kW of electron cyclotron heating (ECH) in the current-fire Advanced Toroidal Facility (ATF) torsatron. Two rail limiters, one at the top and one at the bottom of the device, located at the last closed flux surface (LCFS), are, biased at positive and negative potentials with respect to the vacuum vessel. When the limiters are positively biased at up to 300 V and the plasma density is controlled with a significantly reduced gas feed, the H(sub alpha) radiation from both the limiter and the wall drops, indicating reduced particle recycling as a result of improved particle confinement. For bias voltages around +100 V, there is almost no change of plasma stored energy W(sub p), but W(sub p) then drops with the higher biasing voltages. Positive biasing has caused the core plasma density profile to become peaked and the electric field to become more negative inside the LCFS. At the same time, edge plasma fluctuations are reduced significantly and their power spectrum becomes less broad. The propagation direction of these electrostatic fluctuations reverses to the ion diamagnetic direction, and their wavelengths become longer. The resulting fluctuation-induced particle flux is also reduced. Power deposition on the limiters is lower as a result of reduced edge plasma density and temperature. Negative biasing yields somewhat less improvement in the particle confinement while having almost no apparent effect on W(sub p) or on the core and the edge plasma density and temperature profiles. Simultaneous measurements of the plasma potential profile indicate almost no significant change. Biasing has almost no effect on the intrinsic impurity levels in the plasma.

Progress toward commissioning and plasma operation in NSTX-U

NASA Astrophysics Data System (ADS)

Ono, M.; Chrzanowski, J.; Dudek, L.; Gerhardt, S.; Heitzenroeder, P.; Kaita, R.; Menard, J. E.; Perry, E.; Stevenson, T.; Strykowsky, R.; Titus, P.; von Halle, A.; Williams, M.; Atnafu, N. D.; Blanchard, W.; Cropper, M.; Diallo, A.; Gates, D. A.; Ellis, R.; Erickson, K.; Hosea, J.; Hatcher, R.; Jurczynski, S. Z.; Kaye, S.; Labik, G.; Lawson, J.; LeBlanc, B.; Maingi, R.; Neumeyer, C.; Raman, R.; Raftopoulos, S.; Ramakrishnan, R.; Roquemore, A. L.; Sabbagh, S. A.; Sichta, P.; Schneider, H.; Smith, M.; Stratton, B.; Soukhanovskii, V.; Taylor, G.; Tresemer, K.; Zolfaghari, A.; The NSTX-U Team

2015-07-01

The National Spherical Torus Experiment-Upgrade (NSTX-U) is the most powerful spherical torus facility at PPPL, Princeton USA. The major mission of NSTX-U is to develop the physics basis for an ST-based Fusion Nuclear Science Facility (FNSF). The ST-based FNSF has the promise of achieving the high neutron fluence needed for reactor component testing with relatively modest tritium consumption. At the same time, the unique operating regimes of NSTX-U can contribute to several important issues in the physics of burning plasmas to optimize the performance of ITER. NSTX-U further aims to determine the attractiveness of the compact ST for addressing key research needs on the path toward a fusion demonstration power plant (DEMO). The upgrade will nearly double the toroidal magnetic field BT to 1 T at a major radius of R0 = 0.93 m, plasma current Ip to 2 MA and neutral beam injection (NBI) heating power to 14 MW. The anticipated plasma performance enhancement is a quadrupling of the plasma stored energy and near doubling of the plasma confinement time, which would result in a 5-10 fold increase in the fusion performance parameter nτ T. A much more tangential 2nd NBI system, with 2-3 times higher current drive efficiency compared to the 1st NBI system, is installed to attain the 100% non-inductive operation needed for a compact FNSF design. With higher fields and heating powers, the NSTX-U plasma collisionality will be reduced by a factor of 3-6 to help explore the favourable trend in transport towards the low collisionality FNSF regime. The NSTX-U first plasma is planned for the Summer of 2015, at which time the transition to plasma operations will occur.

NASA Researcher Adjusts a Travelling Magnetic Wave Plasma Engine

NASA Image and Video Library

1964-02-21

Raymond Palmer, of the Electromagnetic Propulsion Division’s Plasma Flow Section, adjusts the traveling magnetic wave plasma engine being operated in the Electric Power Conversion at the National Aeronautics and Space Administration (NASA) Lewis Research Center. During the 1960s Lewis researchers were exploring several different methods of creating electric propulsion systems, including the traveling magnetic wave plasma engine. The device operated similarly to alternating-current motors, except that a gas, not a solid, was used to conduct the electricity. A magnetic wave induced a current as it passed through the plasma. The current and magnetic field pushed the plasma in one direction. Palmer and colleague Robert Jones explored a variety of engine configurations in the Electric Propulsion Research Building. The engine is seen here mounted externally on the facility’s 5-foot diameter and 16-foot long vacuum tank. The four magnetic coils are seen on the left end of the engine. The researchers conducted two-minute test runs with varying configurations and used of both argon and xenon as the propellant. The Electric Propulsion Research Building was built in 1942 as the Engine Propeller Research Building, often called the Prop House. It contained four test cells to study large reciprocating engines with their propellers. After World War II, the facility was modified to study turbojet engines. By the 1960s, the facility was modified again for electric propulsion research and given its current name.

The circuit parameters measurement of the SABALAN-I plasma focus facility and comparison with Lee Model

NASA Astrophysics Data System (ADS)

Karimi, F. S.; Saviz, S.; Ghoranneviss, M.; Salem, M. K.; Aghamir, F. M.

The circuit parameters are investigated in a Mather-type plasma focus device. The experiments are performed in the SABALAN-I plasma focus facility (2 kJ, 20 kV, 10 μF). A 12-turn Rogowski coil is built and used to measure the time derivative of discharge current (dI/dt). The high pressure test has been performed in this work, as alternative technique to short circuit test to determine the machine circuit parameters and calibration factor of the Rogowski coil. The operating parameters are calculated by two methods and the results show that the relative error of determined parameters by method I, are very low in comparison to method II. Thus the method I produces more accurate results than method II. The high pressure test is operated with this assumption that no plasma motion and the circuit parameters may be estimated using R-L-C theory given that C0 is known. However, for a plasma focus, even at highest permissible pressure it is found that there is significant motion, so that estimated circuit parameters not accurate. So the Lee Model code is used in short circuit mode to generate the computed current trace for fitting to the current waveform was integrated from current derivative signal taken with Rogowski coil. Hence, the dynamics of plasma is accounted for into the estimation and the static bank parameters are determined accurately.

Scattering of magnetic mirror trapped electrons by an Alfven wave

NASA Astrophysics Data System (ADS)

Wang, Y.; Gekelman, W. N.; Pribyl, P.; Papadopoulos, K.; Karavaev, A. V.; Shao, X.; Sharma, A. S.

2010-12-01

Highly energetic particles from large solar flares or other events can be trapped in the Earth’s magnetic mirror field and pose a danger to intricate space satellites. Aiming for artificially de-trapping these particles, an experimental and theoretical study of the interactions of a shear Alfven wave with electrons trapped in a magnetic mirror was performed on the Large Plasma Device (LaPD) at UCLA, with critical parameter ratios matched in the lab plasma to those in space. The experiment was done in a quiescent afterglow plasma with ne≈5×1011cm-3, Te≈0.5eV, B0≈1000G, L=18m, and diameter=60cm. A magnetic mirror was established in LaPD (mirror ratio≈1.5, Lmirror≈3m). An electron population with large v⊥ (E⊥≈1keV) was introduced by microwave heating at upper-hybrid frequency with a 2.45GHz pulsed microwave source at up to 5kW. A shear Alfven wave with arbitrary polarization (fwave≈0.5fci , Bwave/B0≈0.5%) was launched by a Rotating Magnetic Field (RMF) antenna axially 2m away from the center of the mirror. It was observed that the Alfven wave effectively eliminated the trapped electrons. A diagnostic probe was developed for this experiment to measure electrons with large v⊥ in the background plasma. Plasma density and temperature perturbations from the Alfven wave were observed along with electron scattering. Computer simulations tracking single particle motion with wave field are ongoing. In these the Alfven wave’s effect on the electrons pitch angle distribution by a Monte-Carlo method is studied. Planned experiments include upgrading the microwave source for up to 100kW pulses to make electrons with higher transverse energy and longer mirror trapping time. This work is supported by The Office of Naval Research under a MURI award. Work was done at the Basic Plasma Science Facility which is supported by DOE and NSF.

Non-uniform Erosion and Surface Evolution of Plasma-Facing Materials for Electric Propulsion

NASA Astrophysics Data System (ADS)

Matthes, Christopher Stanley Rutter

A study regarding the surface evolution of plasma-facing materials is presented. Experimental efforts were performed in the UCLA Pi Facility, designed to explore the physics of plasma-surface interactions. The influence of micro-architectured surfaces on the effects of plasma sputtering is compared with the response of planar samples. Ballistic deposition of sputtered atoms as a result of geometric re-trapping is observed. This provides a self-healing mechanism of micro-architectured surfaces during plasma exposure. This result is quantified using a QCM to demonstrate the evolution of surface features and the corresponding influence on the instantaneous sputtering yield. The sputtering yield of textured molybdenum samples exposed to 300 eV Ar plasma is found to be roughly 1 of the 2 corresponding value of flat samples, and increases with ion fluence. Mo samples exhibited a sputtering yield initially as low as 0.22+/-8%, converging to 0.4+/-8% at high fluence. Although the yield is dependent on the initial surface structure, it is shown to be transient, reaching a steady-state value that is independent of initial surface conditions. A continuum model of surface evolution resulting from sputtering, deposition and surface diffusion is also derived to resemble the damped Kuramoto-Sivashinsky (KS) equation of non-linear dynamics. Linear stability analysis of the evolution equation provides an estimate of the selected wavelength, and its dependence on the ion energy and angle of incidence. The analytical results are confirmed by numerical simulations of the equation with a Fast Fourier Transform method. It is shown that for an initially flat surface, small perturbations lead to the evolution of a selected surface pattern that has nano- scale wavelength. When the surface is initially patterned by other means, the final resulting pattern is a competition between the "templated" pattern and the "self-organized" structure. Potential future routes of research are also discussed, corresponding to a design analysis of the current experimental study.

A novel platform to study magnetized high-velocity collisionless shocks

DOE PAGES

Higginson, D. P.; Korneev, Ph; Béard, J.; ...

2014-12-13

An experimental platform to study the interaction of two colliding high-velocity (0.01–0.2c; 0.05–20 MeV) proton plasmas in a high strength (20 T) magnetic field is introduced. This platform aims to study the collision of magnetized plasmas accelerated via the Target-Normal-Sheath-Acceleration mechanism and initially separated by distances of a few hundred microns. The plasmas are accelerated from solid targets positioned inside a few cubic millimeter cavity located within a Helmholtz coil that provides up to 20 T magnetic fields. Various parameters of the plasmas at their interaction location are estimated. These show an interaction that is highly non-collisional, and that becomesmore » more and more dominated by the magnetic fields as time progresses (from 5 to 60 ps). Particle-in-cell simulations are used to reproduce the initial acceleration of the plasma both via simulations including the laser interaction and via simulations that start with preheated electrons (to save dramatically on computational expense). The benchmarking of such simulations with the experiment and with each other will be used to understand the physical interaction when a magnetic field is applied. In conclusion, the experimental density profile of the interacting plasmas is shown in the case without an applied magnetic magnetic field, so to show that without an applied field that the development of high-velocity shocks, as a result of particle-to-particle collisions, is not achievable in the configuration considered.« less

A novel platform to study magnetized high-velocity collisionless shocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higginson, D. P.; Korneev, Ph; Béard, J.

An experimental platform to study the interaction of two colliding high-velocity (0.01–0.2c; 0.05–20 MeV) proton plasmas in a high strength (20 T) magnetic field is introduced. This platform aims to study the collision of magnetized plasmas accelerated via the Target-Normal-Sheath-Acceleration mechanism and initially separated by distances of a few hundred microns. The plasmas are accelerated from solid targets positioned inside a few cubic millimeter cavity located within a Helmholtz coil that provides up to 20 T magnetic fields. Various parameters of the plasmas at their interaction location are estimated. These show an interaction that is highly non-collisional, and that becomesmore » more and more dominated by the magnetic fields as time progresses (from 5 to 60 ps). Particle-in-cell simulations are used to reproduce the initial acceleration of the plasma both via simulations including the laser interaction and via simulations that start with preheated electrons (to save dramatically on computational expense). The benchmarking of such simulations with the experiment and with each other will be used to understand the physical interaction when a magnetic field is applied. In conclusion, the experimental density profile of the interacting plasmas is shown in the case without an applied magnetic magnetic field, so to show that without an applied field that the development of high-velocity shocks, as a result of particle-to-particle collisions, is not achievable in the configuration considered.« less

Preliminary results from the Small Negative Ion Facility (SNIF) at CCFE

NASA Astrophysics Data System (ADS)

Zacks, J.; McAdams, R.; Booth, J.; Flinders, K.; Holmes, A. J. T.; Simmonds, M.; Stevens, B.; Stevenson, P.; Surrey, E.; Warder, S.; Whitehead, A.; Young, D.

2013-02-01

At Culham Centre for Fusion Energy, a new beam extraction test facility has been built with the purpose of studying and enhancing negative ion beam production and transport. The multipole hydrogen ion source is based on a RF generated plasma using a continuous 5kW power supply operating at the industrial standard frequency of 13.56MHz. The cylindrical source has a diameter of 30cm and a depth of 20cm, with a flat spiral antenna driving the source through a quartz window. The magnet configuration is arranged to produce a dipole filter field across the ion source close to the plasma grid. The plasma load is matched to the RF generator using a Pi matching network. The accelerator uses a single extraction aperture of 14mm diameter, with a biased insert for electron suppression. The accelerator is a triode design with a beam energy of up to 30kV. The beamline consists of a turbomolecular pumped vacuum tank with an instrumented beam dump and ports for additional diagnostics. The ITER Neutral Beam source operates with the enhancement of caesium, which, when scaled up to a reactor, will be heavily consumed. The small size of SNIF allows for fast turn around of modifications and alternative materials to caesium can be tested. A full description of the facility and planned diagnostics is given. Initial results are presented, including measurements and calculations of the plasma load on the RF generator, and beam extraction measurements.

Exchange interaction effects on waves in magnetized quantum plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trukhanova, Mariya Iv., E-mail: mar-tiv@yandex.ru; Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru

2015-02-15

We have applied the many-particle quantum hydrodynamics that includes the Coulomb exchange interaction to magnetized quantum plasmas. We considered a number of wave phenomena that are affected by the Coulomb exchange interaction. Since the Coulomb exchange interaction affects the longitudinal and transverse-longitudinal waves, we focused our attention on the Langmuir waves, the Trivelpiece-Gould waves, the ion-acoustic waves in non-isothermal magnetized plasmas, the dispersion of the longitudinal low-frequency ion-acoustic waves, and low-frequency electromagnetic waves at T{sub e} ≫ T{sub i}. We have studied the dispersion of these waves and present the numeric simulation of their dispersion properties.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omelchenko, Yuri A.

Global interactions of energetic ions with magnetoplasmas and neutral gases lie at the core of many space and laboratory plasma phenomena ranging from solar wind entry into and transport within planetary magnetospheres and exospheres to fast-ion driven instabilities in fusion devices to astrophysics-in-lab experiments. The ability of computational models to properly account for physical effects that underlie such interactions, namely ion kinetic, ion cyclotron, Hall, collisional and ionization processes is important for the success and planning of experimental research in plasma physics. Understanding the physics of energetic ions, in particular their nonlinear resonance interactions with Alfvén waves, is central tomore » improving the heating performance of magnetically confined plasmas for future energy generation. Fluid models are not adequate for high-beta plasmas as they cannot fully capture ion kinetic and cyclotron physics (e.g., ion behavior in the presence of magnetic nulls, shock structures, plasma interpenetration, etc.). Recent results from global reconnection simulations show that even in a MHD-like regime there may be significant differences between kinetic and MHD simulations. Therefore, kinetic modeling becomes essential for meeting modern day challenges in plasma physics. The hybrid approximation is an intermediate approximation between the fluid and fully kinetic approximations. It eliminates light waves, removes the electron inertial temporal and spatial scales from the problem and enables full-orbit ion kinetics. As a result, hybrid codes have become effective tools for exploring ion-scale driven phenomena associated with ion beams, shocks, reconnection and turbulence that control the large-scale behavior of laboratory and space magnetoplasmas. A number of numerical issues, however, make three-dimensional (3D) large-scale hybrid simulations of inhomogeneous magnetized plasmas prohibitively expensive or even impossible. To resolve these difficulties we have developed a novel Event-driven Multiscale Asynchronous Parallel Simulation (EMAPS) technology that replaces time stepping with self-adaptive update events. Local calculations are carried out only on an “as needed basis”. EMAPS (i) guarantees accurate and stable processing of physical variables in time accurate simulations, and (ii) eliminates unnecessary computation. Applying EMAPS to the hybrid model has resulted in the development of a unique parallel code, dimension-independent (compile-time-configurable) HYPERS (Hybrid Parallel Event-Resolved Simulator) that scales to hundreds of thousands of parallel processors. HYPERS advances electromagnetic fields and particles asynchronously on time scales determined by local physical laws and mesh properties. To achieve high computational accuracy in complex device geometries, HYPERS employs high-fidelity Cartesian grids with masked conductive cells. The HYPERS model includes multiple ion species, energy and momentum conserving ion-ion collisions, and provides a number of approximations for plasma resistivity and vacuum regions. Both local and periodic boundary conditions are allowed. The HYPERS solver preserves zero divergence of magnetic field. The project has demonstrated HYPERS capabilities on a number of applications of interest to fusion and astrophysical plasma physics applications listed below. 1. Theta-pinch formation of FRCs The formation, spontaneous spin-up, and stability of theta-pinch formed field-reversed configurations have been studied self-consistently in 3D. The end-to-end hybrid simulations reveal poloidal profiles of implosion-driven fast toroidal plasma rotation and demonstrate three discharge regimes as a function of experimental parameters: the decaying stable configuration, the tilt unstable configuration, and the nonlinear evolution of a fast growing tearing mode. 2. FRC collisions with magnetic mirrors Interactions of fast plasma streams and objects with magnetic obstacles (dipoles, mirrors, etc) lie at the core of many space and laboratory plasma phenomena ranging from magnetoshells and solar wind interactions with planetary magnetospheres to compact fusion plasmas. HYPERS simulations are compared with data from the MSX experiment (LANL) that focuses on the physics of magnetized collisionless shocks through the acceleration and subsequent stagnation of FRC plasmoids against a strong magnetic mirrors and flux-conserving boundaries. 3. Exploding magnetoplasmas Results from hybrid simulations of two experiments at the LAPD and Nevada Terawatt Facility are discussed where short-pulse lasers are used to ablate solid targets to produce plasmas that expand across external magnetic fields. The first simulation recreates flutelike density striations observed at the leading edge of a carbon plasma and predicts an early destruction of the magnetic cavity in agreement with experimental evidence. In the second simulation a polyethylene target is ablated into a mixture of protons and carbon ions. A mechanism is demonstrated that allows protons to penetrate the magnetic field in the form of a collimated flow. The results are compared to experimental data and single-fluid MHD simulations. The EMAPS framework has the potential for wide application in many other engineering and scientific fields, such as climate models, biological systems, electronic devices, seismic events, oil reservation simulators that all involve advancing solutions of partial differential equations in time where the rate of activity can be adapted widely over the spatial domain depending on locally space/time phenomena (“events”).« less

Electromagnetic radiation from beam-plasma instabilities

NASA Technical Reports Server (NTRS)

Pritchett, P. L.; Dawson, J. M.

1983-01-01

A computer simulation is developed for the generation of electromagnetic radiation in an electron beam-plasma interaction. The plasma is treated as a two-dimensional finite system, and effects of a continuous nonrelativistic beam input are accounted for. Three momentum and three field components are included in the simulation, and an external magnetic field is excluded. EM radiation generation is possible through interaction among Langmuir oscillations, ion-acoustic waves, and the electromagnetic wave, producing radiation perpendicular to the beam. The radiation is located near the plasma frequency, and polarized with the E component parallel to the beam. The scattering of Langmuir waves caused by ion-acoustic fluctuations generates the radiation. Comparison with laboratory data for the three-wave interactions shows good agreement in terms of the radiation levels produced, which are small relative to the plasma thermal energy.

Evaluation of Cooling Conditions for a High Heat Flux Testing Facility Based on Plasma-Arc Lamps

DOE PAGES

Charry, Carlos H.; Abdel-khalik, Said I.; Yoda, Minami; ...

2015-07-31

The new Irradiated Material Target Station (IMTS) facility for fusion materials at Oak Ridge National Laboratory (ORNL) uses an infrared plasma-arc lamp (PAL) to deliver incident heat fluxes as high as 27 MW/m 2. The facility is being used to test irradiated plasma-facing component materials as part of the joint US-Japan PHENIX program. The irradiated samples are to be mounted on molybdenum sample holders attached to a water-cooled copper rod. Depending on the size and geometry of samples, several sample holders and copper rod configurations have been fabricated and tested. As a part of the effort to design sample holdersmore » compatible with the high heat flux (HHF) testing to be conducted at the IMTS facility, numerical simulations have been performed for two different water-cooled sample holder designs using the ANSYS FLUENT 14.0 commercial computational fluid dynamics (CFD) software package. The primary objective of this work is to evaluate the cooling capability of different sample holder designs, i.e. to estimate their maximum allowable incident heat flux values. 2D axisymmetric numerical simulations are performed using the realizable k-ε turbulence model and the RPI nucleate boiling model within ANSYS FLUENT 14.0. The results of the numerical model were compared against the experimental data for two sample holder designs tested in the IMTS facility. The model has been used to parametrically evaluate the effect of various operational parameters on the predicted temperature distributions. The results were used to identify the limiting parameter for safe operation of the two sample holders and the associated peak heat flux limits. The results of this investigation will help guide the development of new sample holder designs.« less

Modeling Ultraviolet Emissions Near Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.

2000-01-01

In this report, we describe work awarded to Science Applications International Corporation, for the period 6/l/99 to 5/31/00. During this time period, we have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the role this interaction plays in producing ultraviolet (UV) emissions from neutral oxygen and sulfur. Io, the innermost of Jupiter's Galilean satellites, plays a unique role in the jovian magnetosphere. Neutral material that escapes from Io is ionized to form the lo torus, a dense, heavy-ion plasma that corotates with Jupiter and interacts with Io. Io supplies not only the torus, but is a major source of plasma for the entire magnetosphere. Ionization and charge-exchange of neutrals near lo strongly influences the plasma interaction, and Io's neutral atmosphere plays an important role in the generation of currents that couple Io to Jupiter. There have been no in situ measurements of the neutral density near Io, but remote observations of neutrals near lo have been performed for many years. Recent observations from the Hubble Space Telescope (HST) have shown detailed structure in UV emissions from neutral species near Io. Electron-impact of the neutrals by the Io torus plasma is the primary mechanism responsible for exciting these emissions. Previously, we have modeled the Io plasma environment using three-dimensional magnetohydrodynamic (MHD) simulations, and we have shown that the interaction between Io and the plasma torus plays an important role in producing the morphology of the observed emissions. In the past year, we have extended these studies to use both UV observations and Galileo particle and field measurements to investigate the Io interaction.

FLARE: a New User Facility to Study Multiple-Scale Physics of Magnetic Reconnection Through in-situ Measurements

NASA Astrophysics Data System (ADS)

Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W. S.; Chen, Y.; Cutler, R.; Fox, W.; Hoffmann, F.; Kalish, M.; Jara-Almonte, J.; Myers, C. E.; Ren, Y.; Yamada, M.; Yoo, J.; Bale, S. D.; Carter, T.; Dorfman, S. E.; Drake, J. F.; Egedal, J.; Sarff, J.; Wallace, J.

2016-12-01

The FLARE device (Facility for Laboratory Reconnection Experiments; http://flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton for the studies of magnetic reconnection in the multiple X-line regimes directly relevant to space, solar, astrophysical, and fusion plasmas, as guided by a reconnection phase diagram [Ji & Daughton, Physics of Plasmas 18, 111207 (2011)]. Most of major components either have been already fabricated or are near their completion, including the two most crucial magnets called flux cores. The hardware assembly and installation begin in this summer, followed by commissioning in 2017. Initial comprehensive set of research diagnostics will be constructed and installed also in 2017. The main diagnostics is an extensive set of magnetic probe arrays, covering multiple scales from local electron scales ( ˜ 2 mm) , to intermediate ion scales ( ˜10 cm), and global MHD scales ( ˜ 1 m). The main advantage for the magnetospheric community to use this facility is the ability to simultaneously provide in-situ measurements over all of these relevant scales. By using these laboratory data, not only the detailed spatial profiles around each reconnecting X-line are available for direct comparisons with spacecraft data, but also the global conditions and consequences of magnetic reconnection, which are often difficult to quantify in space, can be controlled or studied systematically. The planned procedures and example topics as a user facility will be discussed in details.

Electron current extraction from a permanent magnet waveguide plasma cathode.

PubMed

Weatherford, B R; Foster, J E; Kamhawi, H

2011-09-01

An electron cyclotron resonance plasma produced in a cylindrical waveguide with external permanent magnets was investigated as a possible plasma cathode electron source. The configuration is desirable in that it eliminates the need for a physical antenna inserted into the plasma, the erosion of which limits operating lifetime. Plasma bulk density was found to be overdense in the source. Extraction currents over 4 A were achieved with the device. Measurements of extracted electron currents were similar to calculated currents, which were estimated using Langmuir probe measurements at the plasma cathode orifice and along the length of the external plume. The influence of facility effects and trace ionization in the anode-cathode gap are also discussed. © 2011 American Institute of Physics

Preliminary Optical Diagnostics of an Helium Plasma Formed with Inductively Coupled Plasma Torch (ICP-T64) and a Non Transferred Arc Plasma Torch

NASA Astrophysics Data System (ADS)

Vacher, D.; Menecier, S.; Dudeck, M.; Katsonis, K.; Berenguer, C.

2012-12-01

Gazeous planets of solar system are mainly composed of helium and hydrogen (respectively about 14 and 86%), with traces of oxygen, carbon, nitrogen, argon, xenon, neon, methane, ammonia and water. The sun itself is composed mainly of hydrogen and helium. In the future purpose of exploring those kind of atmosphere with probes (Juice project or solar orbiter for instance), current authors propose to study such plasma composition, especially to investigate on their radiative properties. For preliminary study, only helium plasma has been producted at atmospheric pressure using two facilities available at LAEPT: an ICP torch and a non-transferred arc plasma torch (NTAPT). Helium spectra obtained are characterized and compared.

Plasma membrane lipid–protein interactions affect signaling processes in sterol-biosynthesis mutants in Arabidopsis thaliana

PubMed Central

Zauber, Henrik; Burgos, Asdrubal; Garapati, Prashanth; Schulze, Waltraud X.

2014-01-01

The plasma membrane is an important organelle providing structure, signaling and transport as major biological functions. Being composed of lipids and proteins with different physicochemical properties, the biological functions of membranes depend on specific protein–protein and protein–lipid interactions. Interactions of proteins with their specific sterol and lipid environment were shown to be important factors for protein recruitment into sub-compartmental structures of the plasma membrane. System-wide implications of altered endogenous sterol levels for membrane functions in living cells were not studied in higher plant cells. In particular, little is known how alterations in membrane sterol composition affect protein and lipid organization and interaction within membranes. Here, we conducted a comparative analysis of the plasma membrane protein and lipid composition in Arabidopsis sterol-biosynthesis mutants smt1 and ugt80A2;B1. smt1 shows general alterations in sterol composition while ugt80A2;B1 is significantly impaired in sterol glycosylation. By systematically analyzing different cellular fractions and combining proteomic with lipidomic data we were able to reveal contrasting alterations in lipid–protein interactions in both mutants, with resulting differential changes in plasma membrane signaling status. PMID:24672530

A ReaxFF-based molecular dynamics study of the mechanisms of interactions between reactive oxygen plasma species and the Candida albicans cell wall

NASA Astrophysics Data System (ADS)

Zhao, T.; Shi, L.; Zhang, Y. T.; Zou, L.; Zhang, L.

2017-10-01

Atmospheric pressure non-equilibrium plasmas have attracted significant attention and have been widely used to inactivate pathogens, yet the mechanisms underlying the interactions between plasma-generated species and bio-organisms have not been elucidated clearly. In this paper, reactive molecular dynamics simulations are employed to investigate the mechanisms of interactions between reactive oxygen plasma species (O, OH, and O2) and β-1,6-glucan (a model for the C. albicans cell wall) from a microscopic point of view. Our simulations show that O and OH species can break structurally important C-C and C-O bonds, while O2 molecules exhibit only weak, non-bonded interactions with β-1,6-glucan. Hydrogen abstraction from hydroxyl or CH groups occurs first in all bond cleavage mechanisms. This is followed by a cascade of bond cleavage and double bond formation events. These lead to the destruction of the fungal cell wall. O and OH have similar effects related to their bond cleavage mechanisms. Our simulation results provide fundamental insights into the mechanisms underlying the interactions between reactive oxygen plasma species and the fungal cell wall of C. albicans at the atomic level.

Arbitrary electron acoustic waves in degenerate dense plasmas

NASA Astrophysics Data System (ADS)

Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

2017-05-01

A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

Influence of nonlinear detuning at plasma wavebreaking threshold on backward Raman compression of non-relativistic laser pulses

NASA Astrophysics Data System (ADS)

Balakin, A. A.; Fraiman, G. M.; Jia, Q.; Fisch, N. J.

2018-06-01

Taking into account the nonlinear dispersion of the plasma wave, the fluid equations for the three-wave (Raman) interaction in plasmas are derived. It is found that, in some parameter regimes, the nonlinear detuning resulting from the plasma wave dispersion during Raman compression limits the plasma wave amplitude to noticeably below the generally recognized wavebreaking threshold. Particle-in-cell simulations confirm the theoretical estimates. For weakly nonlinear dispersion, the detuning effect can be counteracted by pump chirping or, equivalently, by upshifting slightly the pump frequency, so that the frequency-upshifted pump interacts with the seed at the point where the plasma wave enters the nonlinear stage.

Binary collision rates of relativistic thermal plasmas. I Theoretical framework

NASA Technical Reports Server (NTRS)

Dermer, C. D.

1985-01-01

Binary collision rates for arbitrary scattering cross sections are derived in the case of a beam of particles interacting with a Maxwell-Boltzmann (MB) plasma, or in the case of two MB plasmas interacting at generally different temperatures. The expressions are valid for all beam energies and plasma temperatures, from the nonrelativistic to the extreme relativistic limits. The calculated quantities include the reaction rate, the energy exchange rate, and the average rate of change of the squared transverse momentum component of a monoenergetic particle beam as a result of scatterings with particles of a MB plasma. Results are specialized to elastic scattering processes, two-temperature reaction rates, or the cold plasma limit, reproducing previous work.

Interaction of Flowing Plasma with Collecting Objects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchinson, Ian; Haakonsen, Christian Brent; Zhou, Chuteng

Grant DE-SC0010491 has supported ground-breaking research into the wakes and interaction of flowing plasma with collecting objects. This fi nal report outlines the technical achievements and statistics concerning products, participants, and impact.

Model lipid bilayers mimic non-specific interactions of gold nanoparticles with macrophage plasma membranes.

PubMed

Montis, Costanza; Generini, Viola; Boccalini, Giulia; Bergese, Paolo; Bani, Daniele; Berti, Debora

2018-04-15

Understanding the interaction between nanomaterials and biological interfaces is a key unmet goal that still hampers clinical translation of nanomedicine. Here we investigate and compare non-specific interaction of gold nanoparticles (AuNPs) with synthetic lipid and wild type macrophage membranes. A comprehensive data set was generated by systematically varying the structural and physicochemical properties of the AuNPs (size, shape, charge, surface functionalization) and of the synthetic membranes (composition, fluidity, bending properties and surface charge), which allowed to unveil the matching conditions for the interaction of the AuNPs with macrophage plasma membranes in vitro. This effort directly proved for the first time that synthetic bilayers can be set to mimic and predict with high fidelity key aspects of nanoparticle interaction with macrophage eukaryotic plasma membranes. It then allowed to model the experimental observations according to classical interface thermodynamics and in turn determine the paramount role played by non-specific contributions, primarily electrostatic, Van der Waals and bending energy, in driving nanoparticle-plasma membrane interactions. Copyright © 2018 Elsevier Inc. All rights reserved.

Molecular dynamic simulation of weakly magnetized complex plasmas

NASA Astrophysics Data System (ADS)

Funk, Dylan; Konopka, Uwe; Thomas, Edward

2017-10-01

A complex plasma consists of the usual plasma components (electrons, ions and neutrals), as well as a heavier component made of solid, micrometer-sized particles. The particles are in general highly charged as a result of the interaction with the other plasma components. The static and dynamic properties of a complex plasma such as its crystal structure or wave properties are influenced by many forces acting on the individual particles such as the dust particle interaction (a screened Coulomb interaction), neutral (Epstein) drag, the particle inertia and various plasma drag or thermophoretic forces. To study the behavior of complex plasmas we setup an experiment accompanying molecular dynamic simulation. We will present the approach taken in our simulation and give an overview of experimental situations that we want to cover with our simulation such as the particle charge under microgravity condition as performed on the PK-4 space experiment, or to study the detailed influences of high magnetic fields. This work was supported by the US Dept. of Energy (DE-SC0016330), NSF (PHY-1613087) and JPL/NASA (JPL-RSA 1571699).

Plasma wake field XUV radiation source

DOEpatents

Prono, Daniel S.; Jones, Michael E.

1997-01-01

A XUV radiation source uses an interaction of electron beam pulses with a gas to create a plasma radiator. A flowing gas system (10) defines a circulation loop (12) with a device (14), such as a high pressure pump or the like, for circulating the gas. A nozzle or jet (16) produces a sonic atmospheric pressure flow and increases the density of the gas for interacting with an electron beam. An electron beam is formed by a conventional radio frequency (rf) accelerator (26) and electron pulses are conventionally formed by a beam buncher (28). The rf energy is thus converted to electron beam energy, the beam energy is used to create and then thermalize an atmospheric density flowing gas to a fully ionized plasma by interaction of beam pulses with the plasma wake field, and the energetic plasma then loses energy by line radiation at XUV wavelengths Collection and focusing optics (18) are used to collect XUV radiation emitted as line radiation when the high energy density plasma loses energy that was transferred from the electron beam pulses to the plasma.

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

NASA Astrophysics Data System (ADS)

Chen, Zhuojie; She, Didi; Chen, Qinghua; Li, Yanmei; Wu, Wengang

2018-02-01

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

Femtosecond self-reconfiguration of laser-induced plasma patterns in dielectrics

NASA Astrophysics Data System (ADS)

Déziel, Jean-Luc; Dubé, Louis J.; Messaddeq, Sandra H.; Messaddeq, Younès; Varin, Charles

2018-05-01

Laser-induced modification of transparent solids by intense femtosecond laser pulses allows fast integration of nanophotonic and nanofluidic devices with controlled optical properties. Experimental observations suggest that the local and dynamic nature of the interactions between light and the transient plasma plays an important role during fabrication. Current analytical models neglect these aspects and offer limited coverage of nanograting formation on dielectric surfaces. In this paper, we present a self-consistent dynamic treatment of the plasma buildup and its interaction with light within a three-dimensional electromagnetic framework. The main finding of this work is that local light-plasma interactions are responsible for the reorientation of laser-induced periodic plasma patterns with respect to the incident light polarization, when a certain energy density threshold is reached. Plasma reconfiguration occurs within a single laser pulse, on a femtosecond time scale. Moreover, we show that the reconfigured subwavelength plasma structures actually grow into the bulk of the sample, which agrees with the experimental observations of self-organized volume nanogratings. We find that mode coupling of the incident and transversely scattered light with the periodic plasma structures is sufficient to initiate the growth and self-organization of the pattern inside the medium with a characteristic half-wavelength periodicity.

Research methods of plasma stream interaction with heat-resistant materials

NASA Astrophysics Data System (ADS)

Tyuftyaev, A. S.; Gadzhiev, M. Kh; Sargsyan, M. A.; Chinnov, V. F.; Demirov, N. A.; Kavyrshin, D. I.; Ageev, A. G.; Khromov, M. A.

2016-11-01

An experimental automated system was designed and constructed for studying the parameters and characteristics of non-stationary interacting system high-enthalpy-plasma stream-investigated sample: enthalpy of plasma in the incident stream; speed and temperature of plasma stream; temperature of electrons and heavy particles, ionic composition and their spatial distribution; heat flux incident on the sample (kW/cm2); surface temperature of the sample; ablation of the sample material, and others. Measurements of achievable plasma heat flux levels are carried out by calorimetry of plasma streams incident on the surface of multisection copper calorimeter. Determination of acceleration characteristics for profiled plasma torch nozzle, as well as the gas flow rate is produced by measuring the total pressure using the Pitot tube. Video visualization of interacting system is carried out using synchronized high-speed cameras. Micropyrometry of the selected zone on the sample surface is carried out by high-speed, three-wavelength pyrometer. To measure the rate of mass loss of the sample, in addition to the weighing method of evaluation the methods of laser knife and two-position stereoscopy are used. Plasma and sample emission characteristics are performed with two separate spectrometers.

Three-dimensional modeling of the neutral gas depletion effect in a helicon discharge plasma

NASA Astrophysics Data System (ADS)

Kollasch, Jeffrey; Schmitz, Oliver; Norval, Ryan; Reiter, Detlev; Sovinec, Carl

2016-10-01

Helicon discharges provide an attractive radio-frequency driven regime for plasma, but neutral-particle dynamics present a challenge to extending performance. A neutral gas depletion effect occurs when neutrals in the plasma core are not replenished at a sufficient rate to sustain a higher plasma density. The Monte Carlo neutral particle tracking code EIRENE was setup for the MARIA helicon experiment at UW Madison to study its neutral particle dynamics. Prescribed plasma temperature and density profiles similar to those in the MARIA device are used in EIRENE to investigate the main causes of the neutral gas depletion effect. The most dominant plasma-neutral interactions are included so far, namely electron impact ionization of neutrals, charge exchange interactions of neutrals with plasma ions, and recycling at the wall. Parameter scans show how the neutral depletion effect depends on parameters such as Knudsen number, plasma density and temperature, and gas-surface interaction accommodation coefficients. Results are compared to similar analytic studies in the low Knudsen number limit. Plans to incorporate a similar Monte Carlo neutral model into a larger helicon modeling framework are discussed. This work is funded by the NSF CAREER Award PHY-1455210.

Homogeneous reactions of hydrocarbons, silane, and chlorosilanes in radiofrequency plasmas at low pressures

NASA Technical Reports Server (NTRS)

Avni, R.; Carmi, U.; Inspektor, A.; Rosenthal, I.

1984-01-01

The ion-molecule and radical-molecule mechanisms are responsible for the dissociation of hydrocarbon, silane, and chlorosilane monomers and the formation of polymerized species, respectively, in an RF plasma discharge. In a plasma containing a mixture of monomer and argon the rate-determining step for both dissociation and polymerization is governed by an ion-molecule type of interaction. Adding hydrogen or ammonia to the monomer-argon mixture transforms the rate-determining step from an ion-molecule interaction to a radical-molecule interaction for both monomer dissociation and polymerization.

Lagrangian methods in nonlinear plasma wave interaction

NASA Technical Reports Server (NTRS)

Crawford, F. W.

1980-01-01

Analysis of nonlinear plasma wave interactions is usually very complicated, and simplifying mathematical approaches are highly desirable. The application of averaged-Lagrangian methods offers a considerable reduction in effort, with improved insight into synchronism and conservation (Manley-Rowe) relations. This chapter indicates how suitable Lagrangian densities have been defined, expanded, and manipulated to describe nonlinear wave-wave and wave-particle interactions in the microscopic, macroscopic and cold plasma models. Recently, further simplifications have been introduced by the use of techniques derived from Lie algebra. These and likely future developments are reviewed briefly.

Macroscopic Lagrangian description of warm plasmas. II Nonlinear wave interactions

NASA Technical Reports Server (NTRS)

Kim, H.; Crawford, F. W.

1983-01-01

A macroscopic Lagrangian is simplified to the adiabatic limit and expanded about equilibrium, to third order in perturbation, for three illustrative cases: one-dimensional compression parallel to the static magnetic field, two-dimensional compression perpendicular to the static magnetic field, and three-dimensional compression. As examples of the averaged-Lagrangian method applied to nonlinear wave interactions, coupling coefficients are derived for interactions between two electron plasma waves and an ion acoustic wave, and between an ordinary wave, an electron plasma wave, and an ion acoustic wave.

Burning plasma regime for Fussion-Fission Research Facility

NASA Astrophysics Data System (ADS)

Zakharov, Leonid E.

2010-11-01

The basic aspects of burning plasma regimes of Fusion-Fission Research Facility (FFRF, R/a=4/1 m/m, Ipl=5 MA, Btor=4-6 T, P^DT=50-100 MW, P^fission=80-4000 MW, 1 m thick blanket), which is suggested as the next step device for Chinese fusion program, are presented. The mission of FFRF is to advance magnetic fusion to the level of a stationary neutron source and to create a technical, scientific, and technology basis for the utilization of high-energy fusion neutrons for the needs of nuclear energy and technology. FFRF will rely as much as possible on ITER design. Thus, the magnetic system, especially TFC, will take advantage of ITER experience. TFC will use the same superconductor as ITER. The plasma regimes will represent an extension of the stationary plasma regimes on HT-7 and EAST tokamaks at ASIPP. Both inductive discharges and stationary non-inductive Lower Hybrid Current Drive (LHCD) will be possible. FFRF strongly relies on new, Lithium Wall Fusion (LiWF) plasma regimes, the development of which will be done on NSTX, HT-7, EAST in parallel with the design work. This regime will eliminate a number of uncertainties, still remaining unresolved in the ITER project. Well controlled, hours long inductive current drive operation at P^DT=50-100 MW is predicted.

National Spherical Torus Experiment (NSTX) Facility/Diagnostic Overview

NASA Astrophysics Data System (ADS)

Ono, M.

2005-10-01

The capabilities of the NSTX experimental facility and diagnostics continue to improve. The new TF joints are performing well at 4.5 kG. New in-board shaping coils were installed to produce plasmas with simultaneously high elongation ˜2.5 and high triangularity ˜0.8 needed for advanced operation. The EFC/RWM system with six external coils driven by three switching power amplifiers (1 kHz, 6 kA-turn) is now fully operational. With these new tools, we significantly expanded the NSTX operating parameters, achieving the highest controlled elongation of 2.75, a shape factor q95Ip/aBT of 37 MA/m-T, plasma volume of 14 m^3, stored energy of 430 kJ, normalized beta of 7.4 % MA/m-T, bootstrap current fraction of 60 % at 700 kA, and longest plasma pulse length of 1.5 s or about 4 times the resistive skin time. In the area of the plasma diagnostics, ten additional Thomson scattering channels are providing detailed measurement of the H-mode pedestal and internal barrier regions. The 8 channel MSE diagnostic is providing crucial j(r) measurements including high electron confinement reversed shear plasmas. A tangential microwave scattering system to measure electron-transport- relevant fluctuations is being commissioned.

Materials erosion and redeposition studies at the PISCES-facility: net erosion under redeposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirooka, Y.; Goebel, D.M.; Conn, R.W.

1986-05-01

Simultaneous erosion and redeposition of copper and 304 stainless steel under controlled and continuous plasma (D,He,Ar) bombardment has been investigated in the PISCES-facility, which generates typical edge-plasma conditions of magnetic fusion devices. The plasma bombardment conditions are: incident ion flux in the range from 10/sup 17/ to 10/sup 18/ ions/sec/cm/sup 2/, ion bombarding energy of 100 eV, electron temperature in the range from 5 to 15 eV, plasma density in the range from 10/sup 11/ to 10/sup 13/ cm/sup -3/, target temperature in the range from 300 to 900K, and the total ion fluence in the range from 10/sup 20/more » to 10/sup 22/ ions/cm/sup 2/. The net erosion yield under redeposition is found to be significantly smaller than the classical sputtering yield data. A first-order modeling is attempted to interpret the erosion and redeposition behavior of materials under plasma bombardment. It is pointed out both theoretically and experimentally that the mean free path for electron impact ionization of the sputtered material is the key parameter to control the overall mechanism of erosion and redeposition. Strongly modified surface morphologies of bombarded targets are observed and indicate a retrapping effect.« less

Kinetic modeling of streamer penetration into de-ionized water

NASA Astrophysics Data System (ADS)

Levko, Dmitry; Sharma, Ashish; Raja, Laxminarayan L.

2018-03-01

Interest in plasma-liquid interaction phenomena has grown in recent years due to applications in plasma medicine, water purification, and plasma-hydrocarbon reforming. The plasma in contact with liquid is generated, for example, using the plasma jets or streamer discharges. The interaction between the streamer and water can cause both physical and chemical modifications of the liquid. In this paper, the interaction between an anode-directed streamer and the de-ionized water is studied using one-dimensional particle-in-cell Monte Carlo collisions model. In this model, plasma species in both gas and liquid phase are considered as the macro-particles. We find that the penetration of the streamer head into the liquid causes ionization of water molecules by electron impact, a process which is usually ignored in the fluid models. The main charge carriers in the liquid phase are negative water ions which agree with earlier experimental and computational modeling studies. Additionally, we observe an ion-rich sheath in the vicinity of the water surface on the gas side.

Localization of intense electromagnetic waves in plasmas.

PubMed

Shukla, Padma Kant; Eliasson, Bengt

2008-05-28

We present theoretical and numerical studies of the interaction between relativistically intense laser light and a two-temperature plasma consisting of one relativistically hot and one cold component of electrons. Such plasmas are frequently encountered in intense laser-plasma experiments where collisionless heating via Raman instabilities leads to a high-energetic tail in the electron distribution function. The electromagnetic waves (EMWs) are governed by the Maxwell equations, and the plasma is governed by the relativistic Vlasov and hydrodynamic equations. Owing to the interaction between the laser light and the plasma, we can have trapping of electrons in the intense wakefield of the laser pulse and the formation of relativistic electron holes (REHs) in which laser light is trapped. Such electron holes are characterized by a non-Maxwellian distribution of electrons where we have trapped and free electron populations. We present a model for the interaction between laser light and REHs, and computer simulations that show the stability and dynamics of the coupled electron hole and EMW envelopes.

Interaction of monomeric Ebola VP40 protein with a plasma membrane: A coarse-grained molecular dynamics (CGMD) simulation study.

PubMed

Mohamad Yusoff, Mohamad Ariff; Abdul Hamid, Azzmer Azzar; Mohammad Bunori, Noraslinda; Abd Halim, Khairul Bariyyah

2018-06-01

Ebola virus is a lipid-enveloped filamentous virus that affects human and non-human primates and consists of several types of protein: nucleoprotein, VP30, VP35, L protein, VP40, VP24, and transmembrane glycoprotein. Among the Ebola virus proteins, its matrix protein VP40 is abundantly expressed during infection and plays a number of critical roles in oligomerization, budding and egress from the host cell. VP40 exists predominantly as a monomer at the inner leaflet of the plasma membrane, and has been suggested to interact with negatively charged lipids such as phosphatidylinositol 4,5-bisphosphate (PIP 2 ) and phosphatidylserine (PS) via its cationic patch. The hydrophobic loop at the C-terminal domain has also been shown to be important in the interaction between the VP40 and the membrane. However, details of the molecular mechanisms underpinning their interactions are not fully understood. This study aimed at investigating the effects of mutation in the cationic patch and hydrophobic loop on the interaction between the VP40 monomer and the plasma membrane using coarse-grained molecular dynamics simulation (CGMD). Our simulations revealed that the interaction between VP40 and the plasma membrane is mediated by the cationic patch residues. This led to the clustering of PIP 2 around the protein in the inner leaflet as a result of interactions between some cationic residues including R52, K127, K221, K224, K225, K256, K270, K274, K275 and K279 and PIP 2 lipids via electrostatic interactions. Mutation of the cationic patch or hydrophobic loop amino acids caused the protein to bind at the inner leaflet of the plasma membrane in a different orientation, where no significant clustering of PIP 2 was observed around the mutated protein. This study provides basic understanding of the interaction of the VP40 monomer and its mutants with the plasma membrane. Copyright © 2018 Elsevier Inc. All rights reserved.

Laser plasma interaction at an early stage of laser ablation

NASA Astrophysics Data System (ADS)

Lu, Y. F.; Hong, M. H.; Low, T. S.

1999-03-01

Laser scattering and its interaction with plasma during KrF excimer laser ablation of silicon are investigated by ultrafast phototube detection. There are two peaks in an optical signal with the first peak attributed to laser scattering and the second one to plasma generation. For laser fluence above 5.8 J/cm2, the second peak rises earlier to overlap with the first one. The optical signal is fitted by a pulse distribution for the scattered laser light and a drifted Maxwell-Boltzmann distribution with a center-of-mass velocity for the plasma. Peak amplitude and its arrival time, full width at half maximum (FWHM), starting time, and termination time of the profiles are studied for different laser fluences and detection angles. Laser pulse is scattered from both the substrate and the plasma with the latter part as a dominant factor during the laser ablation. Peak amplitude of the scattered laser signal increases but its FWHM decreases with the laser fluence. Angular distribution of the peak amplitude can be fitted with cosn θ(n=4) while the detection angle has no obvious influence on the FWHM. In addition, FWHM and peak amplitude of plasma signal increase with the laser fluence. However, starting time and peak arrival time of plasma signal reduce with the laser fluence. The time interval between plasma starting and scattered laser pulse termination is proposed as a quantitative parameter to characterize laser plasma interaction. Threshold fluence for the interaction is estimated to be 3.5 J/cm2. For laser fluence above 12.6 J/cm2, the plasma and scattered laser pulse distributions tend to saturate.

Opportunities for Utilizing the International Space Station for Studies of F2- Region Plasma Science and High Voltage Solar Array Interactions with the Plasma Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Coffey, Victoria; Wright, Kenneth; Craven, Paul; Koontz, Steven

2010-01-01

The near circular, 51.6deg inclination orbit of the International Space Station (ISS) is maintained within an altitude range of approximately 300 km to 400 km providing an ideal platform for conducting in-situ studies of space weather effects on the mid and low-latitude F-2 region ionosphere. The Floating Potential Measurement Unit (FPMU) is a suite of instruments installed on the ISS in August 2006 which includes a Floating Potential Probe (FPP), a Plasma Impedance Probe (PIP), a Wide-sweep Langmuir Probe (WLP), and a Narrow-sweep Langmuir Probe (NLP). The primary purpose for deploying the FPMU is to characterize ambient plasma temperatures and densities in which the ISS operates and to obtain measurements of the ISS potential relative to the space plasma environment for use in characterizing and mitigating spacecraft charging hazards to the vehicle and crew. In addition to the engineering goals, data from the FPMU instrument package is available for collaborative multi-satellite and ground based instrument studies of the F-region ionosphere during both quiet and disturbed periods. Finally, the FPMU measurements supported by ISS engineering telemetry data provides a unique opportunity to investigate interactions of the ISS high voltage (160 volt) solar array system with the plasma environment. This presentation will provide examples of FPMU measurements along the ISS orbit including night-time equatorial plasma density depletions sampled near the peak electron density in the F2-region ionosphere, charging phenomenon due to interaction of the ISS solar arrays with the plasma environment, and modification of ISS charging due to visiting vehicles demonstrating the capabilities of the FPMU probes for monitoring mid and low latitude plasma processes as well as vehicle interactions with the plasma environment.

Conceptual design of 100 TW solid state laser system

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMordie, J.A.

1995-12-31

Currently the main solid state laser facilities used for plasma physics research in the United Kingdom are the VULCAN laser at the Rutherford Appleton Laboratory and the HELEN facility at the Atomic Weapons Establishment. In the future it is proposed to replace HELEN with a new 100 TW facility to come on line early in the next century. A brief review is given of the VULCAN and HELEN. Then the authors discuss the design for the HELEN replacement.

A unified 3D model for an interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding

NASA Astrophysics Data System (ADS)

Jian, Xiaoxia; Wu, ChuanSong; Zhang, Guokai; Chen, Ji

2015-11-01

A 3D model is developed to perform numerical investigation on the coupled interaction mechanism of the plasma arc, weld pool and keyhole in plasma arc welding. By considering the traveling of the plasma arc along the welding direction, unified governing equations are solved in the whole domain including the torch, plasma arc, keyhole, weld pool and workpiece, which involves different physical mechanisms in different zones. The local thermodynamic equilibrium-diffusion approximation is used to treat the interface between the plasma arc and weld pool, and the volume-of-fluid method is used to track the evolution of the keyhole wall. The interaction effects between the plasma arc, keyhole and weld pool as well as the heat, mass and pressure transport phenomena in the whole welding domain are quantitatively simulated. It is found that when the torch is moving along the joint line, the axis of the keyhole channel tilts backward, and the envelope of molten metal surrounding the keyhole wall inside the weld pool is unsymmetrical relative to the keyhole channel. The plasma arc welding tests are conducted, and the predicted keyhole dimensions and the fusion zone shape are in agreement with the experimentally measured results.

Dumping of auroral kilometric radiation caused by HF heating facility

NASA Astrophysics Data System (ADS)

Mogilevsky, M.; Romantsova, T.; Moiseenko, I.; Bosenger, T.; Rietveld, M.; Hanasz, J.

2012-04-01

We have use measurements of electromagnetic waves and plasma onboard of INTERBALL-2 satellite during joint experiment with Tromso HF heating facility. During the selected event the satellite crossed magnetic flux tube with a footprint at the ionosphere above heater. It was found significant dumping of AKR few minutes after the pumping was switched on. The most prominent dumping was detected at high frequency AKR (500-600 kHz) which were emitted at the height of 2-3 thousands km. Two possible mechanisms of this phenomenon are discussed: (i) reflection AKR from the region with increased electron density and (ii) suppression emission by decrease efficiency of the source caused up going plasma from the heated ionosphere.

Observation of >400-eV precursor plasmas from low-wire-number copper arrays at the 1-MA zebra facility.

PubMed

Coverdale, C A; Safronova, A S; Kantsyrev, V L; Ouart, N D; Esaulov, A A; Deeney, C; Williamson, K M; Osborne, G C; Shrestha, I; Ampleford, D J; Jones, B

2009-04-17

Experiments with cylindrical copper wire arrays at the 1-MA Zebra facility show that high temperatures exist in the precursor plasmas formed when ablated wire array material accretes on the axis prior to the stagnation of a z pinch. In these experiments, the precursor radiated approximately 20% of the >1000 eV x-ray output, and time-resolved spectra show substantial emission from Cu L-shell lines. Modeling of the spectra shows an increase in temperature as the precursor forms, up to approximately 450 eV, after which the temperature decreases to approximately 220-320 eV until the main implosion.

AN INSTRUMENT TO MEASURE THE ELECTRICAL CONDUCTIVITY OF ARC PLASMA JETS

DTIC Science & Technology

The instrument was calibrated by moving aluminum or graphite rods through the transducer. By using thin-wall, stainless steel tubing, the influence ... function for the transducer was also obtained. Tests were run on two different arc plasma jet facilities. Values of s, u ranged from 0.02 to 9 megamhos per second. (Author)

Alleviation of Facility/Engine Interactions in an Open-Jet Scramjet Test Facility

NASA Technical Reports Server (NTRS)

Albertson, Cindy W.; Emami, Saied

2001-01-01

Results of a series of shakedown tests to eliminate facility/engine interactions in an open-jet scramjet test facility are presented. The tests were conducted with the NASA DFX (Dual-Fuel eXperimental scramjet) engine in the NASA Langley Combustion Heated Scramjet Test Facility (CHSTF) in support of the Hyper-X program, The majority of the tests were conducted at a total enthalpy and pressure corresponding to Mach 5 flight at a dynamic pressure of 734 psf. The DFX is the largest engine ever tested in the CHSTF. Blockage, in terms of the projected engine area relative to the nozzle exit area, is 81% with the engine forebody leading edge aligned with the upper edge of the facility nozzle such that it ingests the nozzle boundary layer. The blockage increases to 95% with the engine forebody leading edge positioned 2 in. down in the core flow. Previous engines successfully tested in the CHSTF have had blockages of no more than 51%. Oil flow studies along with facility and engine pressure measurements were used to define flow behavior. These results guided modifications to existing aeroappliances and the design of new aeroappliances. These changes allowed fueled tests to be conducted without facility interaction effects in the data with the engine forebody leading edge positioned to ingest the facility nozzle boundary layer. Interaction effects were also reduced for tests with the engine forebody leading edge positioned 2 in. into the core flow, however some interaction effects were still evident in the engine data. A new shroud and diffuser have been designed with the goal of allowing fueled tests to be conducted with the engine forebody leading edge positioned in the core without facility interaction effects in the data. Evaluation tests of the new shroud and diffuser will be conducted once ongoing fueled engine tests have been completed.

Research of beam conditioning technologies on SG-III laser facility

NASA Astrophysics Data System (ADS)

Zhang, Rui; Su, Jingqin; Yuan, Haoyu; Li, Ping; Tian, Xiaocheng; Wang, Jianjun; Dong, Jun; Zhang, Ying; Yuan, Qiang; Wang, Yuancheng; Zhou, Wei; Peng, Zhitao; Wang, Fang; Hu, Dongxia; Zhu, Qihua; Zheng, Wanguo; Zhang, Xiaomin

2014-12-01

Multi-FM SSD and CPP was experimentally studied in high fluence and will be equipped on all the beams of SG-III laser facility. The output spectrum of the cascade phase modulators are stable and the residual amplitude modulation is small. FM-to-AM effect caused by free-space propagation after using smoothing by spectral dispersion is theoretically analyzed. Results indicate inserting a dispersion grating in places with larger beam aperture could alleviate the FM-to- AM effect, suggesting minimizing free-space propagation and adopting image relay. Experiments taken on SG-III laser facility indicate when the number of color cycles (Nc) adopts 1, imposing of SSD with 3.3 times diffraction limit (TDL) did not lead to pinhole closure in the spatial filters of the preamplifier and main amplifier with 30-TDL pinhole size. The nonuniformity of the focal spot using Multi-FM SSD and CPP drops to 0.26, comparing to 0.84 only using CPP. The experiments solve some key technical problems using SSD and CPP on SG-III laser facility, and provide a flexible platform for laser-plasma interaction experiments. Combined beam smoothing and polarization smoothing are also analyzed. Simulation results indicate through adjusting dispersion directions of one-dimensional SSD beams in a quad, two-dimensional SSD could be obtained. The near field and far field properties of beams using polarization smoothing were also studied, including birefringent wedge and polarization control plate (PCP). By using PCP, cylindrical vector beams could be obtained. New solutions will be provided to solve the LPI problem encountered in indirect drive laser fusion.

Nonlinear wave interaction in a plasma column

NASA Technical Reports Server (NTRS)

Larsen, J.

1972-01-01

Two particular cases of nonlinear wave interaction in a plasma column were investigated. The frequencies of the waves were on the order of magnitude of the electron plasma frequency, and ion motion was neglected. The nonlinear coupling of slow waves on a plasma column was studied by means of cold plasma theory, and the case of a plasma column surrounded by an infinite dielectric in the absence of a magnetic field was also examined. Nonlinear scattering from a plasma column in an electromagnetic field having it's magnetic field parallel to the axis of the column was investigated. Some experimental results on mode conversion in the presence of loss are presented along with some observations of nonlinear scattering, The effect of the earth's magnetic field and of discharge symmetry on the radiation pattern are discussed.

Effect of the size of charged spherical macroparticles on their electrostatic interaction in an equilibrium plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filippov, A. V., E-mail: fav@triniti.ru; Derbenev, I. N.

The effect of the size of two charged spherical macroparticles on their electrostatic interaction in an equilibrium plasma is analyzed within the linearized Poisson–Botzmann model. It is established that, under the interaction of two charged dielectric macroparticles in an equilibrium plasma, the forces acting on each particle turn out to be generally unequal. The forces become equal only in the case of conducting macroparticles or in the case of dielectric macroparticles of the same size and charge. They also turn out to be equal when the surface potentials of the macroparticles remain constant under the variation of interparticle distances. Formulasmore » are proposed that allow one to calculate the interaction force with a high degree of accuracy under the condition that the radii of macroparticles are much less than the screening length, which is usually satisfied in experiments with dusty plasmas.« less

Interactions between large space power systems and low-Earth-orbit plasmas

NASA Technical Reports Server (NTRS)

Stevens, N. J.

1985-01-01

There is a growing tendency to plan space missions that will incorporate very large space power systems. These space power systems must function in the space plasma environment, which can impose operational limitations. As the power output increases, the operating voltage also must increase and this voltage, exposed at solar array interconnects, interacts with the local plasma. The implications of such interactions are considered. The available laboratory data for biased array segment tests are reviewed to demonstrate the basic interactions considered. A data set for a floating high voltage array test was used to generate approximate relationships for positive and negative current collection from plasmas. These relationships were applied to a hypothetical 100 kW power system operating in a 400 km, near equatorial orbit. It was found that discharges from the negative regions of the array are the most probable limiting factor in array operation.