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Sample records for confined plasma target

  1. Plasma confinement at JET

    NASA Astrophysics Data System (ADS)

    Nunes, I.; JET Contributors

    2016-01-01

    Operation with a Be/W wall at JET (JET-ILW) has an impact on scenario development and energy confinement with respect to the carbon wall (JET-C). The main differences observed were (1) strong accumulation of W in the plasma core and (2) the need to mitigate the divertor target temperature to avoid W sputtering by Be and other low Z impurities and (3) a decrease of plasma energy confinement. A major difference is observed on the pedestal pressure, namely a reduction of the pedestal temperature which, due to profile stiffness the plasma core temperature is also reduced leading to a degradation of the global confinement. This effect is more pronounced in low β N scenarios. At high β N, the impact of the wall on the plasma energy confinement is mitigated by the weaker plasma energy degradation with power relative to the IPB98(y, 2) scaling calculated empirically for a CFC first wall. The smaller tolerable impurity concentration for tungsten (<10-5) compared to that of carbon requires the use of electron heating methods to prevent W accumulation in the plasma core region as well as gas puffing to avoid W entering the plasma core by ELM flushing and reduction of the W source by decreasing the target temperature. W source and the target temperature can also be controlled by impurity seeding. Nitrogen and Neon have been used and with both gases the reduction of the W source and the target temperature is observed. Whilst more experiments with Neon are necessary to assess its impact on energy confinement, a partial increase of plasma energy confinement is observed with Nitrogen, through the increase of edge temperature. The challenge for scenario development at JET is to extend the pulse length curtailed by its transient behavior (W accumulation or MHD), but more importantly by the divertor target temperature limits. Re-optimisation of the scenarios to mitigate the effect of the change of wall materials maintaining high global energy confinement similar to JET-C is

  2. Confinement effects of shock waves on laser-induced plasma from a graphite target

    SciTech Connect

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  3. Inertial Confinement fusion targets

    NASA Technical Reports Server (NTRS)

    Hendricks, C. D.

    1982-01-01

    Inertial confinement fusion (ICF) targets are made as simple flat discs, as hollow shells or as complicated multilayer structures. Many techniques were devised for producing the targets. Glass and metal shells are made by using drop and bubble techniques. Solid hydrogen shells are also produced by adapting old methods to the solution of modern problems. Some of these techniques, problems, and solutions are discussed. In addition, the applications of many of the techniques to fabrication of ICF targets is presented.

  4. Tandem mirror plasma confinement apparatus

    DOEpatents

    Fowler, T. Kenneth

    1978-11-14

    Apparatus and method for confining a plasma in a center mirror cell by use of two end mirror cells as positively charged end stoppers to minimize leakage of positive particles from the ends of the center mirror cell.

  5. High Density Plasma Beam Target Fusion: An Alternative form of Inertial Confinement to Ignition

    NASA Astrophysics Data System (ADS)

    Cheng, Dah Yu

    2005-10-01

    A scaling law has been demonstrated for a plasma gun in a 30 m diameter space chamber. Using a specific combination of delay time between the gas valve opening and operation of a capacitor bank switch, and the capacitor bank's voltage, the deflagration gun (Ref. 1) is capable of producing high kinetic energy and at a high density beam. Using a convergent gun barrel it is possible to compress beam density by a factor of 100. A 10^17/c.c.beam was obtained. If the kinetic energy is at 280 Kev (fusion threshold) Neutron flux up to 5 x 10^19 could be produced in a 1 micro-second period. This represents 500 MJ of energy yield. If the classical fusion energy data were in error by a factor of 100 that still would yield 5 MJ of fusion energy. Results obtained from experiments in the 30 m diameter space chamber have demonstrated such a capability using a 120 KV capacitor bank with 200 KJ of stored energy (Ref. 1). A very small scale experiment has demonstrated a yield of 10^15 neutrons using less than 10 kJ of capacitor energy.References:1. Cheng, D.Y. 1970 Plasma Deflagration and the Properties of a Coaxial Plasma Deflagration Gun. Nuclear Fusion, 10, pp. 305- 317

  6. Alternative approaches to plasma confinement

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1978-01-01

    The paper discusses 20 plasma confinement schemes each representing an alternative to the tokamak fusion reactor. Attention is given to: (1) tokamak-like devices (TORMAC, Topolotron, and the Extrap concept), (2) stellarator-like devices (Torsatron and twisted-coil stellarators), (3) mirror machines (Astron and reversed-field devices, the 2XII B experiment, laser-heated solenoids, the LITE experiment, the Kaktus-Surmac concept), (4) bumpy tori (hot electron bumpy torus, toroidal minimum-B configurations), (5) electrostatically assisted confinement (electrostatically stuffed cusps and mirrors, electrostatically assisted toroidal confinement), (6) the Migma concept, and (7) wall-confined plasmas. The plasma parameters of the devices are presented and the advantages and disadvantages of each are listed.

  7. Alternative approaches to plasma confinement

    NASA Technical Reports Server (NTRS)

    Roth, J. R.

    1977-01-01

    The potential applications of fusion reactors, the desirable properties of reactors intended for various applications, and the limitations of the Tokamak concept are discussed. The principles and characteristics of 20 distinct alternative confinement concepts are described, each of which may be an alternative to the Tokamak. The devices are classed as Tokamak-like, stellarator-like, mirror machines, bumpy tori, electrostatically assisted, migma concept, and wall-confined plasma.

  8. Ion beam inertial confinement target

    DOEpatents

    Bangerter, Roger O.; Meeker, Donald J.

    1985-01-01

    A target for implosion by ion beams composed of a spherical shell of frozen DT surrounded by a low-density, low-Z pusher shell seeded with high-Z material, and a high-density tamper shell. The target has various applications in the inertial confinement technology. For certain applications, if desired, a low-density absorber shell may be positioned intermediate the pusher and tamper shells.

  9. CORRELATIONS IN CONFINED QUANTUM PLASMAS

    SciTech Connect

    DUFTY J W

    2012-01-11

    This is the final report for the project 'Correlations in Confined Quantum Plasmas', NSF-DOE Partnership Grant DE FG02 07ER54946, 8/1/2007 - 7/30/2010. The research was performed in collaboration with a group at Christian Albrechts University (CAU), Kiel, Germany. That collaboration, almost 15 years old, was formalized during the past four years under this NSF-DOE Partnership Grant to support graduate students at the two institutions and to facilitate frequent exchange visits. The research was focused on exploring the frontiers of charged particle physics evolving from new experimental access to unusual states associated with confinement. Particular attention was paid to combined effects of quantum mechanics and confinement. A suite of analytical and numerical tools tailored to the specific inquiry has been developed and employed

  10. Multishell inertial confinement fusion target

    DOEpatents

    Holland, James R.; Del Vecchio, Robert M.

    1984-01-01

    A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reaction accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

  11. Multishell inertial confinement fusion target

    DOEpatents

    Holland, James R.; Del Vecchio, Robert M.

    1987-01-01

    A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reactions accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

  12. Fast ignition of inertial confinement fusion targets

    SciTech Connect

    Gus'kov, S. Yu.

    2013-01-15

    Results of studies on fast ignition of inertial confinement fusion (ICF) targets are reviewed. The aspects of the fast ignition concept, which consists in the separation of the processes of target ignition and compression due to the synchronized action of different energy drivers, are considered. Criteria for the compression ratio and heating rate of a fast ignition target, the energy balance, and the thermonuclear gain are discussed. The results of experimental and theoretical studies of the heating of a compressed target by various types of igniting drivers, namely, beams of fast electrons and light ions produced under the action of a petawatt laser pulse on the target, a heavy-ion beam generated in the accelerator, an X-ray pulse, and a hydrodynamic flow of laser-accelerated matter, are analyzed. Requirements to the igniting-driver parameters that depend on the fast ignition criteria under the conditions of specific target heating mechanisms, as well as possibilities of practical implementation of these requirements, are discussed. The experimental programs of various laboratories and the prospects of practical implementation of fast ignition of ICF targets are reviewed. To date, fast ignition is the most promising method for decreasing the ignition energy and increasing the thermonuclear gain of an ICF plasma. A large number of publications have been devoted to investigations of this method and adjacent problems of the physics of igniting drivers and their interaction with plasma. This review presents results of only some of these studies that, in the author's opinion, allow one to discuss in detail the main physical aspects of the fast ignition concept and understand the current state and prospects of studies in this direction.

  13. Experimental Achievements on Plasma Confinement and Turbulence

    SciTech Connect

    Fujisawa, A.

    2009-02-19

    This article presents a brief review of the experimental studies on turbulence and resultant transport in toroidal plasmas. The article focuses on two topics, physics of transport barrier and the role of mesoscale structure on plasma confinement, i.e. zonal flows. The two topics show the important roles of the mutual interactions between sheared flows, zonal flows and drift waves for plasma turbulence and transport. The findings can lead us to further generalized concept of the disparate scale interactions which could give a fundamental understanding of the plasma confinement from the first principle.

  14. Thomson scattering from inertial confinement fusion plasmas

    SciTech Connect

    Glenzer, S.H.; Back, C.A.; Suter, L.J.

    1997-07-08

    Thomson scattering has been developed at the Nova laser facility as a direct and accurate diagnostic to characterize inertial confinement fusion plasmas. Flat disks coated with thin multilayers of gold and beryllium were with one laser beam to produce a two ion species plasma with a controlled amount of both species. Thomson scattering spectra from these plasmas showed two ion acoustic waves belonging to gold and beryllium. The phase velocities of the ion acoustic waves are shown to be a sensitive function of the relative concentrations of the two ion species and are in good agreement with theoretical calculations. These open geometry experiments further show that an accurate measurement of the ion temperature can be derived from the relative damping of the two ion acoustic waves. Subsequent Thomson scattering measurements from methane-filled, ignition-relevant hohlraums apply the theory for two ion species plasmas to obtain the electron and ion temperatures with high accuracy. The experimental data provide a benchmark for two-dimensional hydrodynamic simulations using LASNEX, which is presently in use to predict the performance of future megajoule laser driven hohlraums of the National Ignition Facility (NIF). The data are consistent with modeling using significantly inhibited heat transport at the peak of the drive. Applied to NIF targets, this flux limitation has little effect on x- ray production. The spatial distribution of x-rays is slightly modified but optimal symmetry can be re-established by small changes in power balance or pointing. Furthermore, we find that stagnating plasma regions on the hohlraum axis are well described by the calculations. This result implies that stagnation in gas-filled hohlraums occurs too late to directly affect the capsule implosion in ignition experiments.

  15. Microwave Reflectometry for Magnetically Confined Plasmas

    SciTech Connect

    Mazzucato, E.

    1998-02-01

    This paper is about microwave reflectometry -- a radar technique for plasma density measurements using the reflection of electromagnetic waves by a plasma cutoff. Both the theoretical foundations of reflectometry and its practical application to the study of magnetically confined plasmas are reviewed in this paper. In particular, the role of short-scale density fluctuations is discussed at length, both as a unique diagnostic tool for turbulence studies in thermonuclear plasmas and for the deleterious effects that fluctuations may have on the measurement of the average plasma density with microwave reflectometry.

  16. Inertial-confinement-fusion targets

    SciTech Connect

    Hendricks, C.D.

    1982-08-10

    Much of the research in laser fusion has been done using simple ball on-stalk targets filled with a deuterium-tritium mixture. The targets operated in the exploding pusher mode in which the laser energy was delivered in a very short time (approx. 100 ps or less) and was absorbed by the glass wall of the target. The high energy density in the glass literally exploded the shell with the inward moving glass compressing the DT fuel to high temperatures and moderate densities. Temperatures achieved were high enough to produce DT reactions and accompanying thermonuclear neutrons and alpha particles. The primary criteria imposed on the target builders were: (1) wall thickness, (2) sphere diameter, and (3) fuel in the sphere.

  17. Plasma sheath driven targets

    NASA Astrophysics Data System (ADS)

    Brownell, J. H.; Freeman, B. L.

    1980-02-01

    Plasma focus driven target implosions are simulated using hydrodynamic-burn codes. Support is given to the idea that the use of a target in a plasma focus should allow 'impedance matching' between the fuel and gun, permitting larger fusion yields from a focus-target geometry than the scaling laws for a conventional plasma focus would predict.

  18. PLASMA HEATING AND CONFINING DEVICE

    DOEpatents

    Baker, W.R.; Bratenahl, Al.; Kunkel, W.B.

    1962-02-13

    ABS> A device is designed for generating, heating, and containing a very pure electrical plasma. Plasma purity is maintained by preventing the hot plasma from contacting insulators, which are a principal source of impurities in prior constructions. An insulator is disposed at each end of a pair of long coaxial cylinders forming an annular chamber therebetween. High voltage is applied between the cylinders and an axial magnetic field is created therethrough. At a middle position on the inner cylinder, a fastopening valve releases a quantity of gas into the chamber, and before the gas can diffuse to the distant insulators, a discharge occurs between the cylinders and plasma is formed in the central region of the chamber away from the insulators. (AEC)

  19. The Plasma Anvil in Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Fechner, Walter; Morley, P. D.

    We examine theoretically an inertial confinement fusion (ICF) target consisting of a spherical wedge embedded in a relatively nondeformable "anvil". Questions such as heat loss to the anvil, optimum wedge angle, liner and anvil materials, anvil deformations and deleterious 2-D shock effects on D-T burn and compression symmetry are discussed.

  20. Neoclassical transport in enhanced confinement toroidal plasmas

    SciTech Connect

    Lin, Z.; Tang, W.M.; Lee, W.W.

    1996-11-01

    It has recently been reported that ion thermal transport levels in enhanced confinement tokamak plasmas have been observed to fall below the irreducible minimum level predicted by standard neoclassical theory. This apparent contradiction is resolved in the present analysis by relaxing the basic neoclassical assumption that the ions orbital excursions are much smaller than the local toroidal minor radius and the equilibrium scale lengths of the system.

  1. Integrated models for plasma/material interaction during loss of plasma confinement.

    SciTech Connect

    Hassanein, A.

    1998-07-29

    A comprehensive computer package, High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS), has been developed to evaluate the damage incurred on plasma-facing materials during loss of plasma confinement. The HEIGHTS package consists of several integrated computer models that follow the start of a plasma disruption at the scrape-off layer (SOL) through the transport of the eroded debris and splashed target materials to nearby locations as a result of the energy deposited. The package includes new models to study turbulent plasma behavior in the SOL and predicts the plasma parameters and conditions at the divertor plate. Full two-dimensional comprehensive radiation magnetohydrodynamic models are coupled with target thermodynamics and liquid hydrodynamics to evaluate the integrated response of plasma-facing materials. A brief description of the HEIGHTS package and its capabilities are given in this work with emphasis on turbulent plasma behavior in the SOL during disruptions.

  2. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Eskridge, Richard; Smith, James; Lee, Michael; Richeson, Jeff; Schmidt, George; Knapp, Charles E.; Kirkpatrick, Ronald C.; Turchi, Peter J.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Magnetized target fusion (MTF) attempts to combine the favorable attributes of magnetic confinement fusion (MCF) for energy confinement with the attributes of inertial confinement fusion (ICF) for efficient compression heating and wall-free containment of the fusing plasma. It uses a material liner to compress and contain a magnetized plasma. For practical applications, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC). For the successful implementation of the scheme, plasma jets of the requisite momentum flux density need to be produced. Their transport over sufficiently large distances (a few meters) needs to be assured. When they collide and merge into a liner, relative differences in velocity, density and temperature of the jets could give rise to instabilities in the development of the liner. Variation in the jet properties must be controlled to ensure that the growth rate of the instabilities are not significant over the time scale of the liner formation before engaging with the target plasma. On impact with the target plasma, some plasma interpenetration might occur between the liner and the target. The operating parameter space needs to be identified to ensure that a reasonably robust and conducting contact surface is formed between the liner and the target. A mismatch in the "impedance" between the liner and the target plasma could give rise to undesirable shock heating of the liner leading to increased entropy (thermal losses) in the liner. Any irregularities in the liner will accentuate the Rayleigh-Taylor instabilities during the compression of the target plasma by the liner.

  3. Target plane imager for inertial confinement fusion

    SciTech Connect

    Swift, C.D.; Bliss, E.S.; Jones, W.A.; Seppala, L.G.

    1985-01-30

    The Nova laser, completed in December 1984 at Lawrence Livermore National Laboratory, is being used to conduct inertial confinement fusion experiments. It is capable of focusing more than 100 kJ of energy on small fusion targets. This paper discusses an optical system called the target plane imager that is used during the beam alignment phase of these experiments. The TPI includes a three meter long periscope with a wide field of view, F/3 objective. The telescope relays images of the target focal plane to viewing optics and a video sensor located outside the target chamber. Operation of the system is possible at three wavelengths: 1.05..mu.., 0.527..mu.., and 0.351..mu... These are the three wavelengths at which the ten Nova laser beams can irradiate targets. Both nearfield and farfield images of the ten beams can be viewed with the TPI. This instrument is used to properly align the laser to the target before each target irradiation.

  4. Micromachining of inertial confinement fusion targets

    SciTech Connect

    Gobby, P.L.; Salzer, L.J.; Day, R.D.

    1996-12-31

    Many experiments conducted on today`s largest inertial confinement fusion drive lasers require target components with sub-millimeter dimensions, precisions of a micron or less and surface finishes measured in nanometers. For metal and plastic, techniques using direct machining with diamond tools have been developed that yield the desired parts. New techniques that will be discussed include the quick-flip locator, a magnetically held kinematic mount that has allowed the direct machining of millimeter-sized beryllium hemishells whose inside and outside surface are concentric to within 0.25 micron, and an electronic version of a tracer lathe which has produced precise azimuthal variations of less than a micron.

  5. Confinement Studies in High Temperature Spheromak Plasmas

    SciTech Connect

    Hill, D N; Mclean, H S; Wood, R D; Casper, T A; Cohen, B I; Hooper, E B; LoDestro, L L; Pearlstein, L D; Romero-Talamas, C

    2006-10-23

    Recent results from the SSPX spheromak experiment demonstrate the potential for obtaining good energy confinement (Te > 350eV and radial electron thermal diffusivity comparable to tokamak L-mode values) in a completely self-organized toroidal plasma. A strong decrease in thermal conductivity with temperature is observed and at the highest temperatures, transport is well below that expected from the Rechester-Rosenbluth model. Addition of a new capacitor bank has produced 60% higher magnetic fields and almost tripled the pulse length to 11ms. For plasmas with T{sub e} > 300eV, it becomes feasible to use modest (1.8MW) neutral beam injection (NBI) heating to significantly change the power balance in the core plasma, making it an effective tool for improving transport analysis. We are now developing detailed designs for adding NBI to SSPX and have developed a new module for the CORSICA transport code to compute the correct fast-ion orbits in SSPX so that we can simulate the effect of adding NBI; initial results predict that such heating can raise the electron temperature and total plasma pressure in the core by a factor of two.

  6. Confinement of pure ion plasma in a cylindrical current sheet

    NASA Astrophysics Data System (ADS)

    Paul, Stephen F.; Chao, Edward H.; Davidson, Ronald C.; Phillips, Cynthia K.

    1999-12-01

    A novel method for containing a pure ion plasma at thermonuclear densities and temperatures has been modeled. The method combines the confinement principles of a Penning-Malmberg trap and a pulsed theta-pinch. A conventional Penning trap can confine a uniform-density plasma of about 5×1011cm-3 with a 30-Tesla magnetic field. However, if the axial field is ramped, a much higher local ion density can be obtained. Starting with a 107cm-3 trapped deuterium plasma at the Brillouin limit (B=0.6 Tesla), the field is ramped to 30 Tesla. Because the plasma is comprised of particles of only one sign of charge, transport losses are very low, i.e., the conductivity is high. As a result, the ramped field does not penetrate the plasma and a diamagnetic surface current is generated, with the ions being accelerated to relativistic velocities. To counteract the inward j×B forces from this induced current, additional ions are injected into the plasma along the axis to increase the density (and mutual electrostatic repulsion) of the target plasma. In the absence of the higher magnetic field in the center, the ions drift outward until a balance is established between the outward driving forces (centrifugal, electrostatic, pressure gradient) and the inward j×B force. An equilibrium calculation using a relativistic, 1-D, cold-fluid model shows that a plasma can be trapped in a hollow, 49-cm diameter, 0.2-cm thick cylinder with a density exceeding 4×1014cm-3.

  7. Confinement Studies of Auxiliary Heated NSTX Plasmas

    SciTech Connect

    B.P. LeBlanc; M.G. Bell; R.E. Bell; M.L. Bitter; C. Bourdelle; D.A. Gates; S.M. Kaye; R. Maingi; J.E. Menard; D. Mueller; S.F. Paul; A.L. Roquemore; A. Rosenberg1; S.A. Sabbagh; D. Stutman; E.J. Synakowski; V.A. Soukhanovskii; J.R.Wilson; the NSTX Research Team

    2003-05-06

    The confinement of auxiliary heated NSTX discharges is discussed. The energy confinement time in plasmas with either L-mode or H-mode edges is enhanced over the values given by the ITER97L and ITER98Pby(2) scalings, being up to 2-3 times L-mode and 1.5 times H-mode. TRANSP calculations based on the kinetic profile measurements reproduce the magnetics-based determination of stored energy and the measured neutron production rate. Power balance calculations reveal that, in a high power neutral beam heated H-mode discharge, the ion thermal transport is near neoclassical levels, and well below the electron thermal transport, which is the main loss channel. Perturbative impurity injection techniques indicate the particle diffusivity to be slightly above the neoclassical level in discharges with L-mode edge. High-harmonic fast-wave (HHFW) bulk electron heating is described and thermal transport is discussed. Thermal ion transport is found to be above neoclassical level, but thermal electron transport remains the main loss mechanism. Evidences of an electron thermal internal transport barrier obtained with HHFW heating are presented. A description of H-mode discharges obtained during HHFW heating is presented.

  8. Properties of radio-frequency heated argon confined uranium plasmas

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Pure uranium hexafluoride (UF6) was injected into an argon confined, steady state, rf-heated plasma within a fused silica peripheral wall test chamber. Exploratory tests conducted using an 80 kW rf facility and different test chamber flow configurations permitted selection of the configuration demonstrating the best confinement characteristics and minimum uranium compound wall coating. The overall test results demonstrated applicable flow schemes and associated diagnostic techniques were developed for the fluid mechanical confinement and characterization of uranium within an rf plasma discharge when pure UF6 is injected for long test times into an argon-confined, high-temperature, high-pressure, rf-heated plasma.

  9. Theoretical studies on plasma heating and confinement

    SciTech Connect

    Sudan, R.N.

    1993-01-01

    Three principal topics are covered in this final report: Stabilization of low frequency modes of an axisymmetric compact torus plasma confinement system, such as, spheromaks and FRC'S, by a population of large orbit axis encircling energetic ions. Employing an extension of the energy principle' which utilizes a Vlasov description for the energetic 'ion component, it has been demonstrated that short wavelength MHD type modes are stabilized while the long wavelength tilt and precessional modes are marginally stable. The deformation of the equilibrium configuration by the energetic ions results in the stabilization of the tilt mode for spheromaks. Formation of Ion Rings and their coalescence with spheromaks. A two dimensional electromagnetic PIC codes has been developed for the study of ion ring formation and its propagation, deformation and slowing down in a cold plasma. It has been shown that a ring moving at a speed less than the Alfven velocity can merge with a stationary spheromak. Anomalous transport from drift waves in a Tokomak. The Direct Interaction Approximation in used to obtain incremental transport coefficients for particles and heat for drift waves in a Tokomak. It is shown that the transport matrix does not obey Onsager's principle.

  10. Order in very cold confined plasmas

    SciTech Connect

    Schiffer, J.P. |

    1995-12-31

    The study of the structure and dynamic properties of classical systems of charged particles confined by external forces, and cooled to very low internal energies, is the subject of this talk. An infinite system of identical charged particles has been known for some time to form a body-centered cubic lattice and is a simple classical prototype for condensed matter. Recent technical developments in storage rings, ion traps, and laser cooling of ions, have made it possible to produce such systems in the laboratory, though somewhat modified because of their finite size. I would like to discuss what one may expect in such systems and also show some examples of experiments. If we approximate the potential of an ion trap with an isotropic harmonic force F = {minus}Kr then the Hamiltonian for this collection of ions is the same as that for J. J. Thomson`s ``plum pudding`` model of the atom, where electrons were thought of as discrete negative charges imbedded in a larger, positive, uniformly charged sphere. The harmonic force macroscopically is canceled by the average space-charge forces of the plasma-, and this fixes the overall radius of the distribution. What remains, are the residual two-body Coulomb interactions that keep the particles within the volume as nearly equidistant as possible in order to minimize the potential energy. The configurations obtained for the minimum energy of small ionic systems [2] in isotropic confinement are shown in figure 1. Indeed this is an `Exotic Atom` and fits well into the subject of this symposium honoring the 60th birthday of Professor Toshi Yamazaki.

  11. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Kirkpatrick, Ronald C.; Knapp, Charles E.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Magnetized target fusion is an emerging, relatively unexplored approach to fusion for electrical power and propulsion application. The physical principles of the concept are founded upon both inertial confinement fusion (ICF) and magnetic confinement fusion (MCF). It attempts to combine the favorable attributes of both these orthogonal approaches to fusion, but at the same time, avoiding the extreme technical challenges of both by exploiting a fusion regime intermediate between them. It uses a material liner to compress, heat and contain the fusion reacting plasma (the target plasma) mentally. By doing so, the fusion burn could be made to occur at plasma densities as high as six orders of magnitude higher than conventional MCF such as tokamak, thus leading to an approximately three orders of magnitude reduction in the plasma energy required for ignition. It also uses a transient magnetic field, compressed to extremely high intensity (100's T to 1000T) in the target plasma, to slow down the heat transport to the liner and to increase the energy deposition of charged-particle fusion products. This has several compounding beneficial effects. It leads to longer energy confinement time compared with conventional ICF without magnetized target, and thus permits the use of much lower plasma density to produce reasonable burn-up fraction. The compounding effects of lower plasma density and the magneto-insulation of the target lead to greatly reduced compressional heating power on the target. The increased energy deposition rate of charged-particle fusion products also helps to lower the energy threshold required for ignition and increasing the burn-up fraction. The reduction in ignition energy and the compressional power compound to lead to reduced system size, mass and R&D cost. It is a fusion approach that has an affordable R&D pathway, and appears attractive for propulsion application in the nearer term.

  12. Magnetic Field Required for Ignition in a Magnetically Confined Plasma in Reactor-Type Conditions

    NASA Astrophysics Data System (ADS)

    Panarella, Emilio

    1996-11-01

    A complete and rigorous analysis will be given of the ignition conditions for a pulsed DT plasma magnetically confined, where the conduction losses are introduced from heat transfer theory, rather than from the empirically defined energy confinement time. It will be shown that the magnetic field required for ignition greatly exceeds any of those presently considered for major machines. It will also be shown that ignition is independent of particle density. On the basis of these results it is argued that ignition is facilitated in an inertially confined plasma, both of the classical type with lasers, or with the Spherical Pinch, or the Magnetized Target Fusion concepts.

  13. Self-confinement of finite dust clusters in isotropic plasmas.

    PubMed

    Miloshevsky, G V; Hassanein, A

    2012-05-01

    Finite two-dimensional dust clusters are systems of a small number of charged grains. The self-confinement of dust clusters in isotropic plasmas is studied using the particle-in-cell method. The energetically favorable configurations of grains in plasma are found that are due to the kinetic effects of plasma ions and electrons. The self-confinement phenomenon is attributed to the change in the plasma composition within a dust cluster resulting in grain attraction mediated by plasma ions. This is a self-consistent state of a dust cluster in which grain's repulsion is compensated by the reduced charge and floating potential on grains, overlapped ion clouds, and depleted electrons within a cluster. The common potential well is formed trapping dust clusters in the confined state. These results provide both valuable insights and a different perspective to the classical view on the formation of boundary-free dust clusters in isotropic plasmas.

  14. Alpha Heating and Burning Plasmas in Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Christopherson, A. R.

    2015-11-01

    In inertial confinement fusion, a spherical capsule of cryogenic DT is accelerated inward at a high velocity. Near stagnation, a dense hot spot is formed where the deuterium and tritium ions begin to fuse, creating a 3.5-MeV alpha particle per reaction. These alpha particles deposit energy back into the plasma, thereby increasing the pressure, temperature, and reaction rate. This feedback process is called ``alpha heating,'' and ignition is a direct consequence of this thermal instability. The onset of a burning-plasma regime occurs when the total alpha-particle energy produced exceeds the shell compression work. Using an analytic compressible-shell model for the implosion, it is found that the onset of the burning-plasma regime is a unique function of the neutron yield enhancement caused by alpha particles for any target, direct or indirect drive. This yield enhancement can then be inferred from experimentally measureable quantities, such as the Lawson parameter. From this analysis, the onset of a burning plasma occurs at yields exceeding 50 kJ for implosions at the National Ignition Facility. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

  15. Stellarator approach to toroidal plasma confinement

    SciTech Connect

    Johnson, J.L.

    1981-12-01

    An overview is presented of the development and current status of the stellarator approach to controlled thermonuclear confinement. Recent experimental, theoretical, and systems developments have made this concept a viable option for the evolution of the toroidal confinement program. Some experimental study of specific problems associated with departure from two-dimensional symmetry must be undertaken before the full advantages and opportunities of steady-state, net-current-free operation can be realized.

  16. Heat flow in a gravitationally confined plasma

    NASA Astrophysics Data System (ADS)

    Dorelli, John Charles

    We study the problem of electron heat flow in a gravitationally confined hilly ionized plasma. Our goal is to determine the conditions under which the classical description of electron heat flow-which requires heat to flow down the local temperature gradient-breaks down. We investigate this question from both a macroscopic (fluid theory) and a microscopic (kinetic theory) point of view. We use fluid conservation laws to demonstrate generally that a nearly isotropic non-Maxwellian electron velocity distribution can have a heat flux vector which points up the local temperature gradient. As a specific example, we demonstrate that electron velocity distributions with high energy power law tails in the solar corona can have a heat flux vector which points up a radially directed temperature gradient. We confirm this result by numerically solving the steady state Fokker-Planck equation describing the electron velocity distribution in the presence of a strong gravitational field. Our conclusions can be summarized as follows: (1)It is possible for a nearly isotropic electron velocity distribution with a weak power law tail near the base of the solar corona to have a heat flux which points up a radially directed temperature gradient, (2)The Spitzer-Harm theory does not give an adequate description of electron heat flow in the solar corona for any finite temperature gradient (no matter how small), (3)If the electron velocity distribution function at the base of the corona does not have a non- Maxwellian tail which connects nearly collisionlessly to the high altitude boundary, then the electron phase space density develops a spatial boundary layer near the low altitude boundary of the system. This spatial boundary layer implies large anisotropies in the electron velocity distribution which cannot be described self consistently by the mathematical model employed in this thesis, (4)If the electron velocity distribution functions at the boundaries of the system have nearly

  17. Alpha Heating and Burning Plasmas in Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Betti, R.; Christopherson, A. R.; Bose, A.; Woo, K. M.

    2016-05-01

    Assessing the degree to which fusion alpha particles contribute to the fusion yield is essential to understanding the onset of the thermal runaway process of thermonuclear ignition. It is shown that in inertial confinement fusion, the yield enhancement due to alpha particle heating (before ignition occurs) depends on the generalized Lawson parameter that can be inferred from experimental observables. A universal curve valid for arbitrary laser-fusion targets shows the yield amplification due to alpha heating for a given value of the Lawson parameter. The same theory is used to determine the onset of the burning plasma regime when the alpha heating exceeds the compression work. This result can be used to assess the performance of current ignition experiments at the National Ignition Facility.

  18. Magnetic confinement of a high-density cylindrical plasma

    SciTech Connect

    Ahedo, Eduardo

    2011-10-15

    The stationary structure of a weakly collisional plasma column, confined by an axial magnetic field and a cylindrical vessel, is studied for the high-density case, when the diamagnetic azimuthal current is large enough to demagnetize partially the plasma. The plasma response is characterized mainly by two dimensionless parameters: the ratios of the electron gyroradius and the electron skin-depth to the plasma radius, and each of them measures the independent influence of the applied magnetic field and the plasma density on the plasma response. The strong magnetic confinement regime, characterized by very small wall losses, is limited to the small gyroradius and large skin-depth ranges. In the high-density case, when the electron skin-depth is smaller than the electron gyroradius, the skin-depth turns out to be the magnetic screening length, so that the bulk of the plasma behaves as unmagnetized.

  19. Investigating inertial confinement fusion target fuel conditions through x-ray spectroscopy

    SciTech Connect

    Hansen, Stephanie B.

    2012-05-15

    Inertial confinement fusion (ICF) targets are designed to produce hot, dense fuel in a neutron-producing core that is surrounded by a shell of compressing material. The x-rays emitted from ICF plasmas can be analyzed to reveal details of the temperatures, densities, gradients, velocities, and mix characteristics of ICF targets. Such diagnostics are critical to understand the target performance and to improve the predictive power of simulation codes.

  20. Progress In Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Francis Y. C.; Kirkpatrick, Ronald C.; Knapp, Charles E.; Cassibry, Jason; Eskridge, Richard; Lee, Michael; Smith, James; Martin, Adam; Wu, S. T.; Schmidt, George; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Magnetized target fusion (MTF) attempts to combine the favorable attributes of magnetic confinement fusion (MCF) for energy confinement with the attributes of inertial confinement fusion (ICF) for efficient compression heating and wall-free containment of the fusing plasma. It uses a material liner to compress and contain a magnetized plasma. For practical applications, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC).

  1. Laser-plasma interactions relevant to Inertial Confinement Fusion

    SciTech Connect

    Wharton, K.B.

    1998-11-02

    Research into laser-driven inertial confinement fusion is now entering a critical juncture with the construction of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Many of the remaining unanswered questions concerning NIF involve interactions between lasers and plasmas. With the eventual goal of fusion power in mind, laser-plasma interactions relevant to laser fusion schemes is an important topic in need of further research. This work experimentally addresses some potential shortcuts and pitfalls on the road to laser-driven fusion power. Current plans on NIF have 192 laser beams directed into a small cylindrical cavity which will contain the fusion fuel; to accomplish this the beams must cross in the entrance holes, and this intersection will be in the presence of outward-flowing plasma. To investigate the physics involved, interactions of crossing laser beams in flowing plasmas are investigated with experiments on the Nova laser facility at LLNL. It was found that in a flowing plasma, energy is transferred between two crossing laser beams, and this may have deleterious consequences for energy balance and ignition in NIF. Possible solutions to this problem are presented. A recently-proposed alternative to standard laser-driven fusion, the ''fast ignitor'' concept, is also experimentally addressed in this dissertation. Many of the laser-plasma interactions necessary for the success of the fast ignitor have not previously been explored at the relevant laser intensities. Specifically, the transfer of high-intensity laser energy to electrons at solid-target interfaces is addressed. 20-30% conversion efficiencies into forward-propagated electrons were measured, along with an average electron energy that varied with the type of target material. The directionality of the electrons was also measured, revealing an apparent beaming of the highest energy electrons. This work was extended to various intensities and pulse lengths and a

  2. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much_lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  3. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  4. Magnetic confinement system using charged ammonia targets

    DOEpatents

    Porter, Gary D.; Bogdanoff, Anatoly

    1979-01-01

    A system for guiding charged laser targets to a predetermined focal spot of a laser along generally arbitrary, and especially horizontal, directions which comprises a series of electrostatic sensors which provide inputs to a computer for real time calculation of position, velocity, and direction of the target along an initial injection trajectory, and a set of electrostatic deflection means, energized according to a calculated output of said computer, to change the target trajectory to intercept the focal spot of the laser which is triggered so as to illuminate the target of the focal spot.

  5. Laser targets compensate for limitations in inertial confinement fusion drivers

    NASA Astrophysics Data System (ADS)

    Kilkenny, J. D.; Alexander, N. B.; Nikroo, A.; Steinman, D. A.; Nobile, A.; Bernat, T.; Cook, R.; Letts, S.; Takagi, M.; Harding, D.

    2005-10-01

    Success in inertial confinement fusion (ICF) requires sophisticated, characterized targets. The increasing fidelity of three-dimensional (3D), radiation hydrodynamic computer codes has made it possible to design targets for ICF which can compensate for limitations in the existing single shot laser and Z pinch ICF drivers. Developments in ICF target fabrication technology allow more esoteric target designs to be fabricated. At present, requirements require new deterministic nano-material fabrication on micro scale.

  6. Laboratory-scale uranium RF plasma confinement experiments

    NASA Technical Reports Server (NTRS)

    Roman, W. C.

    1976-01-01

    An experimental investigation was conducted using 80 kW and 1.2 MW RF induction heater facilities to aid in developing the technology necessary for designing a self-critical fissioning uranium plasma core reactor. Pure uranium hexafluoride (UF6) was injected into argon-confined, steady-state, RF-heated plasmas in different uranium plasma confinement tests to investigate the characteristics of plamas core nuclear reactors. The objectives were: (1) to confine as high a density of uranium vapor as possible within the plasma while simultaneously minimizing the uranium compound wall deposition; (2) to develop and test materials and handling techniques suitable for use with high-temperature, high-pressure gaseous UF6; and (3) to develop complementary diagnostic instrumentation and measurement techniques to characterize the uranium plasma and residue deposited on the test chamber components. In all tests, the plasma was a fluid-mechanically-confined vortex-type contained within a fused-silica cylindrical test chamber. The test chamber peripheral wall was 5.7 cm ID by 10 cm long.

  7. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2006-04-11

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  8. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2013-06-11

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  9. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2006-10-31

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  10. Apparatus for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2016-07-05

    An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  11. Probing cell migration in confined environments by plasma lithography.

    PubMed

    Junkin, Michael; Wong, Pak Kin

    2011-03-01

    Cellular processes are regulated by various mechanical and physical factors in their local microenvironment such as geometric confinements, cell-substrate interactions, and cell-cell contact. Systematic elucidation of these regulatory mechanisms is crucial for fundamental understanding of cell biology and for rational design of biomedical devices and regenerative medicine. Here, we report a generally applicable plasma lithography technique, which performs selective surface functionalization on large substrate areas, for achieving long-term, stable confinements with length scales from 100 nm to 1 cm toward the investigation of cell-microenvironment interactions. In particular, we applied plasma lithography for cellular confinement of neuroblastomas, myoblasts, endothelial cells, and mammary gland epithelial cells, and examined the motion of mouse embryonic fibroblasts in directionality-confined environments for studying the effect of confinements on migratory behavior. In conjunction with live cell imaging, the distance traveled, velocity, and angular motion of individual cells and collective cell migration behaviors were measured in confined environments with dimensions comparable to a cell. A critical length scale that a cell could conceivably occupy and migrate to was also identified by investigating the behaviors of cells using confined environments with subcellular length scales.

  12. Divertor plasma conditions and neutral dynamics in horizontal and vertical divertor configurations in JET-ILW low confinement mode plasmas

    NASA Astrophysics Data System (ADS)

    Groth, M.; Brezinsek, S.; Belo, P.; Brix, M.; Calabro, G.; Chankin, A.; Clever, M.; Coenen, J. W.; Corrigan, G.; Drewelow, P.; Guillemaut, C.; Harting, D.; Huber, A.; Jachmich, S.; Järvinen, A.; Kruezi, U.; Lawson, K. D.; Lehnen, M.; Maggi, C. F.; Marchetto, C.; Marsen, S.; Maviglia, F.; Meigs, A. G.; Moulton, D.; Silva, C.; Stamp, M. F.; Wiesen, S.

    2015-08-01

    Measurements of the plasma conditions at the low field side target plate in JET ITER-like wall ohmic and low confinement mode plasmas show minor differences in divertor plasma configurations with horizontally and vertically inclined targets. Both the reduction of the electron temperature in the vicinity of the strike points and the rollover of the ion current to the plates follow the same functional dependence on the density at the low field side midplane. Configurations with vertically inclined target plates, however, produce twice as high sub-divertor pressures for the same upstream density. Simulations with the EDGE2D-EIRENE code package predict significantly lower plasma temperatures at the low field side target in vertical than in horizontal target configurations. Including cross-field drifts and imposing a pumping by-pass leak at the low-field side plate can still not recover the experimental observations.

  13. Magnetohydrodynamically generated velocities in confined plasma

    SciTech Connect

    Morales, Jorge A. Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.

    2015-04-15

    We investigate by numerical simulation the rotational flows in a toroid confining a conducting magnetofluid in which a current is driven by the application of externally supported electric and magnetic fields. The computation involves no microscopic instabilities and is purely magnetohydrodynamic (MHD). We show how the properties and intensity of the rotations are regulated by dimensionless numbers (Lundquist and viscous Lundquist) that contain the resistivity and viscosity of the magnetofluid. At the magnetohydrodynamic level (uniform mass density and incompressible magnetofluids), rotational flows appear in toroidal, driven MHD. The evolution of these flows with the transport coefficients, geometry, and safety factor are described.

  14. Magnetohydrodynamically generated velocities in confined plasma

    NASA Astrophysics Data System (ADS)

    Morales, Jorge A.; Bos, Wouter J. T.; Schneider, Kai; Montgomery, David C.

    2015-04-01

    We investigate by numerical simulation the rotational flows in a toroid confining a conducting magnetofluid in which a current is driven by the application of externally supported electric and magnetic fields. The computation involves no microscopic instabilities and is purely magnetohydrodynamic (MHD). We show how the properties and intensity of the rotations are regulated by dimensionless numbers (Lundquist and viscous Lundquist) that contain the resistivity and viscosity of the magnetofluid. At the magnetohydrodynamic level (uniform mass density and incompressible magnetofluids), rotational flows appear in toroidal, driven MHD. The evolution of these flows with the transport coefficients, geometry, and safety factor are described.

  15. Space charge neutralization in inertial electrostatic confinement plasmas

    SciTech Connect

    Evstatiev, E. G.; Nebel, R. A.; Chacon, L.; Park, J.; Lapenta, G.

    2007-04-15

    A major issue for electron injected inertial electrostatic confinement (IEC) devices is space charge neutralization. A new formalism is developed that will allow this neutralization to occur for both oscillating and steady-state IEC plasmas. Results indicate that there are limits on the amount of compression that can be achieved by oscillating plasmas while simultaneously maintaining space charge neutralization and parabolic background potential. For steady-state plasmas, there are no such limits and space charge neutralization can be achieved even when the plasma becomes quasineutral.

  16. Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

    SciTech Connect

    Stratton, B. C.; Biter, M.; Hill, K. W.; Hillis, D. L.; Hogan, J. T.

    2007-07-18

    Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically-confined fusion plasmas, both in determining the effects of impurities on plasma behavior and in measurements of plasma parameters such as electron and ion temperatures and densities, particle transport, and particle influx rates. This paper reviews spectroscopic diagnostics of plasma radiation that are excited by collisional processes in the plasma, which are termed 'passive' spectroscopic diagnostics to distinguish them from 'active' spectroscopic diagnostics involving injected particle and laser beams. A brief overview of the ionization balance in hot plasmas and the relevant line and continuum radiation excitation mechanisms is given. Instrumentation in the soft X-ray, vacuum ultraviolet, ultraviolet, visible, and near-infrared regions of the spectrum is described and examples of measurements are given. Paths for further development of these measurements and issues for their implementation in a burning plasma environment are discussed.

  17. Confinement and heating of a deuterium-tritium plasma

    SciTech Connect

    Hawryluk, R.J.; Adler, H.; Alling, P.; Ancher, C.; Anderson, H.; Anderson, J.L.; Ashcroft, D.; Barnes, C.W.; Barnes, G.; Batha, S.; Bell, M.G.; Bell, R.; Bitter, M.; Blanchard, W.; Bretz, N.L.; Budny, R.; Bush, C.E.; Camp, R.; Caorlin, M.; Cauffman, S.; Chang, Z.; Cheng, C.Z.; Collins, J.; Coward, G.; Darrow, D.S.; DeLooper, J.; Duong, H.; Dudek, L.; Durst, R.; Efthimion, P.C.; Ernst, D.; Fisher, R.; Fonck, R.J.; Fredrickson, E.; Fromm, N.; Fu, G.Y.; Furth, H.P.; Gentile, C.; Gorelenkov, N.; Grek, B.; Grisham, L.R.; Hammett, G.; Hanson, G.R.; Heidbrink, W.; Herrmann, H.W.; Hill, K.W.; Hosea, J.; Hsuan, H.; Janos, A.; Jassby, D.L.; Jobes, F.C.; Johnson, D.W.; Johnson, L.C.; Kamperschroer, J.; Kugel, H.; Lam, N.T.; LaMarche, P.H.; Loughlin, M.J.; LeBlanc, B.; Leonard, M.; Levinton, F.M.; Machuzak, J.; Mansfield, D.K.; Martin, A.; Mazzucato, E.; Majeski, R.; Marmar, E.; McChesney, J.; McCormack, B.; McCune, D.C.; McGuire, K.M.; McKee, G.; Meade, D.M.; Medley, S.S.; Mikkelsen, D.R.; Muelle

    1994-05-30

    The Tomamak Fusion Test reactor has performed initial high-power experiments with the plasma fueled with nominally equal densities of deuterium and tritium. Compared to pure deuterium plasmas, the energy stored in the electron and ions increased by [similar to]20%. These increases indicate improvements in confinement associated with the use of tritium and possibly heating of electrons by [alpha] particles created by the D-T fusion reactions.

  18. Magnetic plasma confinement for laser ion source.

    PubMed

    Okamura, M; Adeyemi, A; Kanesue, T; Tamura, J; Kondo, K; Dabrowski, R

    2010-02-01

    A laser ion source (LIS) can easily provide a high current beam. However, it has been difficult to obtain a longer beam pulse while keeping a high current. On occasion, longer beam pulses are required by certain applications. For example, more than 10 micros of beam pulse is required for injecting highly charged beams to a large sized synchrotron. To extend beam pulse width, a solenoid field was applied at the drift space of the LIS at Brookhaven National Laboratory. The solenoid field suppressed the diverging angle of the expanding plasma and the beam pulse was widened. Also, it was observed that the plasma state was conserved after passing through a few hundred gauss of the 480 mm length solenoid field.

  19. MHD-stable plasma confinement in an axisymmetric mirror system

    SciTech Connect

    Stupakov, G.V.

    1988-02-01

    If the magnetic field of a nonparaxial mirror system is chosen appropriately, it is possible to maintain a sharp plasma boundary in an open axisymmetric confinement system in a manner which is stable against flute modes (both global and small-scale). Stability prevails in the ideal MHD approximation without finite-ion-Larmor radius effects.

  20. Plasma confinement apparatus using solenoidal and mirror coils

    DOEpatents

    Fowler, T. Kenneth; Condit, William C.

    1979-01-01

    A plasma confinement apparatus, wherein multiple magnetic mirror cells are linked by magnetic field lines inside of a solenoid with the mirroring regions for adjacent magnetic mirror cells each formed by a separate mirror coil inside of the solenoid. The magnetic mirror cells may be field reversed.

  1. The RFP: Plasma Confinement with a Reversed Twist.

    NASA Astrophysics Data System (ADS)

    Sarff, John S.

    1997-11-01

    The reversed field pinch (RFP) is an axisymmetric plasma torus which, like the better known tokamak, is confined by a magnetic field partly produced by a current within the plasma itself (i.e., a toroidal pinch) and partly by an external solenoidal magnet. But in the RFP, the field produced by the plasma is dominant. This means that the helical magnetic field lines spiral more tightly in the RFP, like a coiled spring bent into a torus. Also, the field lines near the boundary spiral in reverse direction to the field lines nearer the center of the plasma, like nested springs with opposite pitch, giving the plasma its ``reversed field'' name. Most of RFP physics--including that which is related to its fusion reactor potential--traces to these unique magnetic equilibrium features. Since the externally applied field is small, RFP plasmas naturally produce high β >10%, the ratio of plasma thermal pressure to confining magnetic pressure. But the large plasma current provides free energy for small ~1% magnetic fluctuations which, amazingly, regulate much of the RFP's macroscopic behavior, like generation of equilibrium magnetic field through turbulent < tilde v × tilde b > motion (a ``dynamo effect'') and anomalous transport of particles and energy. In fact without the dynamo, the field line pitch reversal after which the RFP is named would not persist. This tutorial aims to introduce the RFP to those less familiar with the concept. A present and future perspective on recent RFP research which has led to significant advances in our understanding of plasmas with strong magnetic turbulence will be emphasized. Initial efforts and future plans to control magnetic turbulence, thereby improving RFP confinement, will be discussed, and examples of RFP physics with general impact, like the relationship of the RFP dynamo to solar and planetary dynamos, will be noted.

  2. Space-charge-based electrostatic plasma confinement involving relaxed plasma species

    SciTech Connect

    Pacheco, J. L.; Ordonez, C. A.; Weathers, D. L.

    2012-10-15

    A numerical study is reported on the equilibrium properties of a surface-emitted or edge-confined non-drifting plasma. A self-consistent finite-differences evaluation of the electrostatic potential is carried out for a non-neutral plasma that follows a Boltzmann density distribution. The non-neutral plasma generates an electrostatic potential that has an extremum at the geometric center. Poisson's equation is solved for different ratios of the non-neutral plasma size to the edge Debye length. The profiles of the electrostatic potential and the plasma density are presented for different values of that ratio. A second plasma species is then introduced for two-plasma-species confinement studies, with one species confined by the space charge of the other, while each species follows a Boltzmann density distribution. An equilibrium in which a neutral region forms is found. An equilibrium is also found in which the two species have equal temperatures and charge states.

  3. Device for plasma confinement and heating by high currents and nonclassical plasma transport properties

    DOEpatents

    Coppi, B.; Montgomery, D.B.

    1973-12-11

    A toroidal plasma containment device having means for inducing high total plasma currents and current densities and at the same time emhanced plasma heating, strong magnetic confinement, high energy density containment, magnetic modulation, microwaveinduced heating, and diagnostic accessibility is described. (Official Gazette)

  4. Simulation of transition dynamics to high confinement in fusion plasmas

    NASA Astrophysics Data System (ADS)

    Nielsen, A. H.; Xu, G. S.; Madsen, J.; Naulin, V.; Juul Rasmussen, J.; Wan, B. N.

    2015-12-01

    The transition dynamics from the low (L) to the high (H) confinement mode in magnetically confined plasmas is investigated using a first-principles four-field fluid model. Numerical results are in agreement with measurements from the Experimental Advanced Superconducting Tokamak - EAST. Particularly, the slow transition with an intermediate dithering phase is well reproduced at proper parameters. The model recovers the power threshold for the L-H transition as well as the decrease in power threshold switching from single to double null configuration observed experimentally. The results are highly relevant for developing predictive models of the transition, essential for understanding and optimizing future fusion power reactors.

  5. Negative specific heat of a magnetically self-confined plasma torus

    PubMed Central

    Kiessling, Michael K.-H.; Neukirch, Thomas

    2003-01-01

    It is shown that the thermodynamic maximum-entropy principle predicts negative specific heat for a stationary, magnetically self-confined current-carrying plasma torus. Implications for the magnetic self-confinement of fusion plasma are considered. PMID:12576553

  6. K-alpha conversion efficiency measurments for x-ray scattering in inertial confinement fusion plasmas

    SciTech Connect

    Kritcher, A L; Neumayer, P; Urry, M K; Robey, H; Niemann, C; Landen, O L; Morse, E; Glenzer, S H

    2006-11-21

    The conversion efficiency of ultra short-pulse laser radiation to K-{alpha} x-rays has been measured for various chlorine-containing targets to be used as x-ray scattering probes of dense plasmas. The spectral and temporal properties of these sources will allow spectrally-resolved x-ray scattering probing with picosecond temporal resolution required for measuring the plasma conditions in inertial confinement fusion experiments. Simulations of x-ray scattering spectra from these plasmas show that fuel capsule density, capsule ablator density, and shock timing information may be inferred.

  7. Confinement projections for the Burning Plasma Experiment (BPX)

    SciTech Connect

    Goldston, R.J.; Bateman, G.; Kaye, S.M.; Perkins, F.W.; Pomphrey, N.; Stotler, D.P.; Zarnstorff, M.C. . Plasma Physics Lab.); Houlberg, W.A.; Neilson, G.H. ); Porkolab, M. ); Reidel, K.S. ); Stambaugh, R.D.; Waltz, R.E. )

    1991-01-01

    The mission of the Burning Plasma Experiment (BPX, formerly CIT) is to study the physics of self-heated fusion plasmas (Q = 5 to ignition), and to demonstrate the production of substantial amounts of fusion power (P{sub fus} = 100 to 500 MW). Confinement projections for BPX have been made on the basis of (1) dimensional extrapolation (2) theory-based modeling calibrated to experiment, and (3) statistical scaling from the available empirical data base. The results of all three approaches, discussed in this paper, roughly coincide. We presently view the third approach, statistical scaling, as the most reliable means for projecting the confinement performance of BPX, and especially for assessing the uncertainty in the projection. 11 refs., 2 figs., 1 tab.

  8. Symmetry Constraints on the Dynamics of Magnetically Confined Plasma

    SciTech Connect

    Arter, Wayne

    2009-05-15

    In respect of their symmetry properties, toroidal magnetically confined plasmas have much in common with the Taylor-Couette flow. A symmetry-based analysis (equivalent bifurction theory) has proved very powerful in the analysis of the latter problem. This Letter discusses the applicability of the method to nuclear fusion experiments such as tokamaks and pinches. The likely behavior of the simplest models of rotationally symmetric tokamaks is described, and found to be potentially consistent with observation.

  9. Magnetohydrodynamics equilibrium of a self-confined elliptical plasma ball

    SciTech Connect

    Wu, H. P. O. Box 8730, Beijing 100080 and Institute of Mechanics, Academia Sinica, Beijing, People's Republic of China ); Oakes, M.E. )

    1991-08-01

    A variational principle is applied to the problem of magnetohydrodynamics (MHD) equilibrium of a self-contained elliptical plasma ball, such as elliptical ball lightning. The principle is appropriate for an approximate solution of partial differential equations with arbitrary boundary shape. The method reduces the partial differential equation to a series of ordinary differential equations and is especially valuable for treating boundaries with nonlinear deformations. The calculations conclude that the pressure distribution and the poloidal current are more uniform in an oblate self-confined plasma ball than that of an elongated plasma ball. The ellipticity of the plasma ball is obviously restricted by its internal pressure, magnetic field, and ambient pressure. Qualitative evidence is presented for the absence of sighting of elongated ball lightning.

  10. Implicit Methods for the Magnetohydrodynamic Description of Magnetically Confined Plasmas

    SciTech Connect

    Jardin, S C

    2010-09-28

    Implicit algorithms are essential for predicting the slow growth and saturation of global instabilities in today’s magnetically confined fusion plasma experiments. Present day algorithms for obtaining implicit solutions to the magnetohydrodynamic (MHD) equations for highly magnetized plasma have their roots in algorithms used in the 1960s and 1970s. However, today’s computers and modern linear and non-linear solver techniques make practical much more comprehensive implicit algorithms than were previously possible. Combining these advanced implicit algorithms with highly accurate spatial representations of the vector fields describing the plasma flow and magnetic fields and with improved methods of calculating anisotropic thermal conduction now makes possible simulations of fusion experiments using realistic values of plasma parameters and actual configuration geometry.

  11. US/Russian Magnetized Target Fusion Plasma Formation Experiments

    NASA Astrophysics Data System (ADS)

    Benage, John F., Jr.; Mtf Team; Broste, W.; Westley, D.; Mago Team

    1998-11-01

    Magnetized target fusion (MTF) is a potentially very low cost route to producing a fusion energy source. Many of MTF's plasma properties are intermediate between magnetically confined fusion (MFE) and inertially confined fusion (ICF). MTF consists of first producing a magnetically thermally insulated target plasma with a temperature of 100 eV or more with a lifetime of 5-10 microseconds. The target plasma is then compressed to fusion conditions by a magnetically driven imploding liner. One target plasma candidate is VNIIEF's MAGO, in which a cylindrical chamber with two cavities is filled with DT gas at a pressure of 10 Torr and driven by a current of 2-8 MA. A series of experiments under different plasma conditions have been performed to evaluate MAGO as an MTF target plasma. Diagnostics used to characterize the MAGO plasma include B dot probes to measure the current distribution, filtered silicon diodes to measure the spectrum and duration of the plasma radiation and a UV spectrometer to measure impurity line radiation.

  12. Magnetic-compression/magnetized-target fusion (MAGO/MTF): A marriage of inertial and magnetic confinement

    SciTech Connect

    Lindemuth, I.R.; Ekdahl, C.A.; Kirkpatrick, R.C.

    1996-12-31

    Intermediate between magnetic confinement (MFE) and inertial confinement (ICF) in time and density scales is an area of research now known in the US as magnetized target fusion (MTF) and in Russian as MAGO (MAGnitnoye Obzhatiye--magnetic compression). MAGO/MTF uses a magnetic field and preheated, wall-confined plasma fusion fuel within an implodable fusion target. The magnetic field suppresses thermal conduction losses in the fuel during the target implosion and hydrodynamic compression heating process. In contrast to direct, hydrodynamic compression of initially ambient-temperature fuel (i.e., ICF), MAGO/MTF involves two steps: (a) formation of a warm (e.g., 100 eV or higher), magnetized (e.g., 100 kG) plasma within a fusion target prior to implosion; (b) subsequent quasi-adiabatic compression by an imploding pusher, of which a magnetically driven imploding liner is one example. In this paper, the authors present ongoing activities and potential future activities in this relatively unexplored area of controlled thermonuclear fusion.

  13. Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets

    NASA Technical Reports Server (NTRS)

    Annamalai, P.; Lee, M. C.; Crawley, R. L.; Downs, R. L.

    1985-01-01

    An inertial confinement fusion (ICF) target made of polystyrene is first levitated in an acoustic field. The surface of the target is then etched using an appropriate solution (e.g., cyclohexane) to enhance the wetting characteristics. A specially prepared polyvinyl alcohol solution is atomized using an acoustic atomizer and deposited on the surface of the target. The solution is air dried to form a thin coating (2 microns) on the target (outside diameter of about 350-850 microns). Thicker coatings are obtained by repeated applications of the coating solutions. Preliminary results indicate that uniform coatings may be achievable on the targets with a background surface smoothness in the order of 1000 A.

  14. Inertial Confinement Fusion Target Component Fabrication and Technology Development Support

    SciTech Connect

    Steinman, D.

    1993-03-01

    On December 31, 1990, the US Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion (ICF) Target Component Fabrication and Technology Development Support contractor. This report documents the technical activities of the period January 1, 1991 through September 30, 1992. During this period, GA was assigned 15 tasks in support of the Inertial Confinement Fusion program and its laboratories. These tasks included Facilities Activation, Staff Development, and Capabilities Validation to establish facilities and equipment, and demonstrate capability to perform ICF target fabrication research, development and production activities. The capabilities developed and demonstrated are those needed for fabrication and precise characterization of polymer shells and polymer coatings. We made progress toward production capability for glass shells, barrier layer coatings, and gas idling of shells. We fabricated over 1000 beam diagnostic foil targets for Sandia National Laboratory Albuquerque and provided full-time on-site engineering support for target fabrication and characterization. We initiated development of methods to fabricate polymer shells by a controlled mass microencapsulation technique, and performed chemical syntheses of several chlorine- and silicon-doped polymer materials for the University of Rochester's Laboratory for Laser Energetics (UR/LLE). We performed the conceptual design of a cryogenic target handling system for UR/LLE that will fill, transport, layer, and characterize targets filled with cryogenic deuterium or deuterium-tritium fuel, and insert these cryogenic targets into the OMEGA-Upgrade target chamber for laser implosion experiments. This report summarizes and documents the technical progress made on these tasks.

  15. Confinement of Plasma along Shaped Open Magnetic Fields from the Centrifugal Force of Supersonic Plasma Rotation

    SciTech Connect

    Teodorescu, C.; Young, W. C.; Swan, G. W. S.; Ellis, R. F.; Hassam, A. B.; Romero-Talamas, C. A.

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic ExB rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  16. Particle confinement of pellet-fuelled tokamak plasma

    NASA Astrophysics Data System (ADS)

    Valovič, M.; Axon, K.; Garzotti, L.; Saarelma, S.; Thyagaraja, A.; Akers, R.; Gurl, C.; Kirk, A.; Lloyd, B.; Maddison, G. P.; Morris, A. W.; Patel, A.; Shibaev, S.; Scannell, R.; Taylor, D.; Walsh, M.; MAST Team

    2008-07-01

    This paper quantifies the particle confinement of pellet-fuelled plasmas as measured in the Mega Ampere Spherical Tokamak. The dataset is restricted mostly to neutral beam heated plasmas in H-mode and to shallow pellets launched from the high-field side. It is shown that the pellet deposition can be explained only by invoking the ∇B drift of the pellet ablatant. The pellet creates a zone with positive density gradient and increased temperature gradient. Simulations show that these changes could increase the level of micro-turbulence and thus enhance further the penetration of pellet-deposited particles towards the core. Post-pellet dynamics of the density profile is characterized by the pellet retention time τpel. It is shown that τpel correlates with the status of the edge transport barrier (L-mode or H-mode) and decreases rapidly for pellet deposition radius rpel approaching the plasma edge. For ELMy H-mode and pellet deposition radius of rpel ≈ 0.8a, the pellet retention time is about 20% of the energy confinement time. The fuelling requirement by the pellets for ITER and the Component Test Facility based on the spherical tokamak is discussed.

  17. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    Matter-antimatter annihilation releases more energy per unit mass than any other method of energy production, making it an attractive energy source for spacecraft propulsion. In the magnetically confined plasma engine, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas. The resulting charged annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. The calculated energy transfer efficiencies for a low number density (10(14)/cu cm) hydrogen propellant are insufficient to warrant operating the engine in this mode. Efficiencies are improved using moderate propellant number densities (10(16)/cu cm), but the energy transferred to the plasma in a realistic magnetic mirror system is generally limited to less than 2 percent of the initial proton-antiproton annihilation energy. The energy transfer efficiencies are highest for high number density (10(18)/cu cm) propellants, but plasma temperatures are reduced by excessive radiation losses. Low to moderate thrust over a wide range of specific impulse can be generated with moderate propellant number densities, while higher thrust but lower specific impulse may be generated using high propellant number densities. Significant mass will be required to shield the superconducting magnet coils from the high energy gamma radiation emitted by neutral pion decay. The mass of such a radiation shield may dominate the total engine mass, and could severely diminish the performance of antiproton powered engines which utilize magnetic confinement. The problem is compounded in the antiproton powered plasma engine, where lower energy plasma bremsstrahlung radiation may cause shield surface ablation and degradation.

  18. Spectroscopic, imaging, and probe diagnostics of laser plasma plumes expanding between confining surfaces

    SciTech Connect

    Yeates, P.; Kennedy, E. T.

    2010-11-15

    Laser plasma plumes were generated in aluminum rectangular cavities of fixed depth (6 mm) and varying height (2.0, 1.5, and 1.0 mm). Space and time resolved visible emission spectroscopy, gated intensified visible imaging, and Langmuir probe diagnostics were utilized to diagnose the evolution of the confined plasma plumes in comparison to freely expanding plasma plume generated from ablation of a planar target. The constrained plasma behavior displayed a multiphase history. Early stage interactions (t<100 ns) resulted in enhanced continuum and line emission, shockwave formation and plasma plume rebound. Later phase, long duration plasma-surface interactions (t>160 ns) resulted in sustained 'decay', i.e., a rapid termination of continuum emission, in concert with decreases in peak electron density (N{sub e}) and plasma temperature (T). This later phase originates from loss mechanisms which bleed the plasma plume of thermal energy and charged particles. These loss mechanisms increase in magnitude as the duration of the plasma-surface interaction increases. The transition from enhancement phase, originating from hydrodynamic containment, and plasma-surface collisions, to decay phase is described and occurs for each cavity at a different point in the space time history.

  19. Confinement of complex plasmas by dielectric walls under microgravity

    SciTech Connect

    Klindworth, M.; Arp, O.; Piel, A.

    2005-10-31

    Dusty plasmas have been confined by glass walls in order to generate void-free particle structures under microgravity conditions. Different types of clouds establish in the cuvette in dependence on the rf power and dc bias applied to the multi-electrode system of the discharge device. The observations can be basically understood when applying standard force models to discharge simulation results. The various dust topologies are proposed to result from a change in the direction of the ion drag - inwards or outwards the cuvette gap.

  20. Finite Time Lyapunov Exponents for magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Sugiyama, Linda; Krishnan, Harinarayan

    2012-10-01

    Finite Time Lyapunov Exponents (FTLEs) are applied for the first time to magnetically confined plasmas. The FTLE measures the local divergence or convergence of n-dimensional vector fields. Time-dependent FTLEs are directly related to Lagrangian Coherent Structures, which form the underlying structure of turbulent flows. Modern FTLE methods, developed over the past decade, are evolving rapidly and leading to new practical and theoretical insights into turbulent fluid dynamics. In contrast to fluids, an MHD plasma has two vector fields, the magnetic field and the plasma flow. Accurate methods for computing and visualizing FTLEs for the MHD fields have been developed, based on the VisIt visualization package. They are applied to time slices of a large sawtooth crash in a toroidal plasma, computed by the M3D extended MHD code. The plasma structures for both B and v have unexpected properties that are not brought out by conventional analyses. The sawtooth crash is also found to have well-organized ``flow'' structures in v±B. The FTLE appears to be a sensitive diagnostic for the structure of stochastic magnetic fields. The methods are not restricted to MHD, since they apply to almost any vector field.

  1. Multiple-beam laser–plasma interactions in inertial confinement fusion

    SciTech Connect

    Myatt, J. F. Zhang, J.; Maximov, A. V.; Short, R. W.; Seka, W.; Edgell, D. H.; Michel, D. T.; Igumenshchev, I. V.; Froula, D. H.; Hinkel, D. E.; Michel, P.; Moody, J. D.

    2014-05-15

    The experimental evidence for multiple-beam laser-plasma instabilities of relevance to laser driven inertial confinement fusion at the ignition scale is reviewed, in both the indirect and direct-drive approaches. The instabilities described are cross-beam energy transfer (in both indirectly driven targets on the NIF and in direct-drive targets), multiple-beam stimulated Raman scattering (for indirect-drive), and multiple-beam two-plasmon decay instability (in direct drive). Advances in theoretical understanding and in the numerical modeling of these multiple beam instabilities are presented.

  2. High-performance inertial confinement fusion target implosions on OMEGA

    SciTech Connect

    Meyerhofer, D. D.; McCrory, R L; Betti, R; Boehly, T R; Casey, D T; Collins, T.J.B.; Craxton, R S; Delettrez, J A; Edgell, D H; Epstein, R; Fletcher, K A; Frenje, J A; Glebov, Y Yu; Goncharov, V N; Harding, D R; Hu, S X; Igumenshchev, I V; Knauer, J P; Li, C K; Marozas, J A; Marshall, F J; McKenty, P W; Nilson, P M; Padalino, S P; Petrasso, R D; Radha, P B; Regan, S P; Sangster, T C; Seguin, F H; Seka, W; Short, R W; Shvarts, D; Skupsky, S; Soures, J M; Stoeckl, C; Theobald, W; Yaakobi, B

    2011-04-18

    The Omega Laser Facility is used to study inertial confinement fusion (ICF) concepts. This paper describes progress in direct-drive central hot-spot (CHS) ICF, shock ignition (SI) and fast ignition (FI) since the 2008 IAEA FEC conference. CHS cryogenic deuterium-tritium (DT) target implosions on OMEGA have produced the highest DT areal densities yet measured in ICF implosions (~300 mg cm{sup -2}). Integrated FI experiments have shown a significant increase in neutron yield caused by an appropriately timed high-intensity, high-energy laser pulse.

  3. Measurements of uranium mass confined in high density plasmas

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1976-01-01

    An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

  4. Proposed generation and compression of a target plasma for MTF

    SciTech Connect

    Kirkpatrick, R.C.; Thurston, R.S.; Chrien, R.E.

    1995-09-01

    Magnetized target fusion (MTF), in which a magnetothermally insulated plasma is hydrodynamically compressed to fusion conditions, represents an approach to controlled fusion which avoids difficulties of both traditional inertial confinement and magnetic confinement approaches. The authors are proposing to demonstrate the feasibility of magnetized target fusion by: (1) creating a suitable magnetized target plasma, (2) performing preliminary liner compression experiments using existing pulsed power facilities and demonstrated liner performance. Once the target plasma and the means for its generation have been optimized, the authors plan to conduct preliminary liner compression experiments aimed at demonstrating the near-adiabatic compression of the target plasma desired for MTF. Relevant liner compression experiments have been performed at Los Alamos in the Scyllac Fast Liner Program and, more recently, in the Pegasus facility and the Procyon explosive pulsed power program. In a series of liner experiments they plan to map out the dependence of temperature and neutron production as functions of the initial plasma conditions and the liner compression achieved. With the above research program, they intend to demonstrate most of the key principles involved in magnetized target fusion, and develop the experimental and theoretical tools needed to design and execute fully integrated MTF ignition experiments.

  5. Alpha Heating and Burning Plasmas in Inertial Confinement Fusion.

    PubMed

    Betti, R; Christopherson, A R; Spears, B K; Nora, R; Bose, A; Howard, J; Woo, K M; Edwards, M J; Sanz, J

    2015-06-26

    Estimating the level of alpha heating and determining the onset of the burning plasma regime is essential to finding the path towards thermonuclear ignition. In a burning plasma, the alpha heating exceeds the external input energy to the plasma. Using a simple model of the implosion, it is shown that a general relation can be derived, connecting the burning plasma regime to the yield enhancement due to alpha heating and to experimentally measurable parameters such as the Lawson ignition parameter. A general alpha-heating curve is found, independent of the target and suitable to assess the performance of all laser fusion experiments whether direct or indirect drive. The onset of the burning plasma regime inside the hot spot of current implosions on the National Ignition Facility requires a fusion yield of about 50 kJ. PMID:26197131

  6. Alpha heating and burning plasmas in inertial confinement fusion

    SciTech Connect

    Betti, R.; Christopherson, A. R.; Spears, B. K.; Nora, R.; Bose, A.; Howard, J.; Woo, K. M.; Edwards, M. J.; Sanz, J.

    2015-06-01

    Estimating the level of alpha heating and determining the onset of the burning plasma regime is essential to finding the path towards thermonuclear ignition. In a burning plasma, the alpha heating exceeds the external input energy to the plasma. Using a simple model of the implosion, it is shown that a general relation can be derived, connecting the burning plasma regime to the yield enhancement due to alpha heating and to experimentally measurable parameters such as the Lawson ignition parameter. A general alpha-heating curve is found, independent of the target and suitable to assess the performance of all laser fusion experiments whether direct or indirect drive. The onset of the burning plasma regime inside the hot spot of current implosions on the National Ignition Facility requires a fusion yield of about 50 kJ.

  7. Alpha Heating and Burning Plasmas in Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Betti, R.; Christopherson, A. R.; Spears, B. K.; Nora, R.; Bose, A.; Howard, J.; Woo, K. M.; Edwards, M. J.; Sanz, J.

    2015-06-01

    Estimating the level of alpha heating and determining the onset of the burning plasma regime is essential to finding the path towards thermonuclear ignition. In a burning plasma, the alpha heating exceeds the external input energy to the plasma. Using a simple model of the implosion, it is shown that a general relation can be derived, connecting the burning plasma regime to the yield enhancement due to alpha heating and to experimentally measurable parameters such as the Lawson ignition parameter. A general alpha-heating curve is found, independent of the target and suitable to assess the performance of all laser fusion experiments whether direct or indirect drive. The onset of the burning plasma regime inside the hot spot of current implosions on the National Ignition Facility requires a fusion yield of about 50 kJ.

  8. Experiments on Plasma Injection into a Centrifugally Confined System

    NASA Astrophysics Data System (ADS)

    Messer, S.; Bomgardner, R.; Brockington, S.; Case, A.; Witherspoon, F. D.; Uzun-Kaymak, I.; Elton, R.; Young, W.; Teodorescu, C.; Morales, C. H.; Ellis, R. F.

    2009-11-01

    We describe the cross-field injection of plasma into a centrifugally-confined system. Two different types of plasma railgun have been installed on the Maryland Centrifugal Experiment (MCX) in an attempt to drive that plasma's rotation. The initial gun was a coaxial device designed to mitigate the blowby instability. The second one was a MiniRailgun with a rectangular bore oriented so that the MCX magnetic field augments the railgun's internal magnetic field. Tests at HyperV indicate this MiniRailgun reaches much higher densities than the original gun, although muzzle velocity is slightly reduced. We discuss the impact of these guns on MCX for various conditions. Initial results show that even for a 2 kG field, firing the MiniRailgun modifies oscillations of the MCX diamagnetic loops and can impact the core current and voltage. The gun also has a noticeable impact on MCX microwave emissions. These observations suggest plasma enters the MCX system. We also compare diagnostic data collected separately from MCX for these and other guns, focussing primarily on magnetic measurements.

  9. Cryogenic DT and D2 targets for inertial confinement fusiona)

    NASA Astrophysics Data System (ADS)

    Sangster, T. C.; Betti, R.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Elasky, L. M.; Glebov, V. Yu.; Goncharov, V. N.; Harding, D. R.; Jacobs-Perkins, D.; Janezic, R.; Keck, R. L.; Knauer, J. P.; Loucks, S. J.; Lund, L. D.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Radha, P. B.; Regan, S. P.; Seka, W.; Shmayda, W. T.; Skupsky, S.; Smalyuk, V. A.; Soures, J. M.; Stoeckl, C.; Yaakobi, B.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Séguin, F. H.; Moody, J. D.; Atherton, J. A.; MacGowan, B. D.; Kilkenny, J. D.; Bernat, T. P.; Montgomery, D. S.

    2007-05-01

    Ignition target designs for inertial confinement fusion on the National Ignition Facility (NIF) [W. J. Hogan et al., Nucl. Fusion 41, 567 (2001)] are based on a spherical ablator containing a solid, cryogenic-fuel layer of deuterium and tritium. The need for solid-fuel layers was recognized more than 30 years ago and considerable effort has resulted in the production of cryogenic targets that meet most of the critical fabrication tolerances for ignition on the NIF. At the University of Rochester's Laboratory for Laser Energetics (LLE), the inner-ice surface of cryogenic DT capsules formed using β-layering meets the surface-smoothness requirement for ignition (<1-μm rms in all modes). Prototype x-ray-drive cryogenic targets being produced at the Lawrence Livermore National Laboratory are nearing the tolerances required for ignition on the NIF. At LLE, these cryogenic DT (and D2) capsules are being imploded on the direct-drive 60-beam, 30-kJ UV OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The designs of these cryogenic targets for OMEGA are energy scaled from the baseline direct-drive-ignition design for the NIF. Significant progress with the formation and characterization of cryogenic targets for both direct and x-ray drive will be described. Results from recent cryogenic implosions will also be presented.

  10. Numerical modeling of the transition from low to high confinement in magnetically confined plasma

    NASA Astrophysics Data System (ADS)

    Rasmussen, J. Juul; Nielsen, A. H.; Madsen, J.; Naulin, V.; Xu, G. S.

    2016-01-01

    The transition dynamics from low (L) to high (H) mode confinement in magnetically confined plasmas is investigated using a four-field drift fluid model—HESEL (Hot Edge-Sol-Electrostatic). The model includes profile evolution and is solved in a 2D domain at the out-board mid-plane of a tokamak including both open and closed field lines. The results reveal different types of L-H-like transitions in response to ramping up the input power by increasing the ion temperature in the edge region. For a fast rising input power we obtain an abrupt transition, and for a slow rising power we obtain a L-I-H transition with an intermediate I-phase displaying limit-cycle oscillations (LCO). The model recovers the power threshold for the L-H transition, the scaling of the threshold with the density and with the loss-rate in the SOL, indicating a decrease in power threshold when switching from single to double null configuration. The results hold promises for developing full predictive modeling of the L-H transition, which is an essential step in understanding and optimizing fusion devices.

  11. Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

    SciTech Connect

    Singh, S. C. Fallon, C.; Hayden, P.; Yeates, P.; Costello, J. T.; Mujawar, M.

    2014-09-15

    Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

  12. Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

    NASA Astrophysics Data System (ADS)

    Singh, S. C.; Fallon, C.; Hayden, P.; Mujawar, M.; Yeates, P.; Costello, J. T.

    2014-09-01

    Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

  13. Target debris collection studies for inertial confinement fusion (ICF) experiments

    NASA Astrophysics Data System (ADS)

    Grim, G. P.; Archuleta, T. N.; Bradley, P. A.; Fowler, M. M.; Hayes, A. C.; Jungman, G.; Obst, A. W.; Rundberg, R. S.; Vieira, D. J.; Wang, Y. Q.; Wilhelmy, J. B.

    2010-08-01

    At the recently completed National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, the initial set of diagnostics to be deployed are focused on measuring neutrons and γ's generated by d(t,n)α reactions in the imploded capsule. Although valuable for understanding pre-ignition experiments, this abbreviated diagnostic suite provides an incomplete picture of the plasma conditions obtained. Prompt radiochemical techniques, based on induced neutron and charged particle reactions within the imploded target, provide a novel and interesting new perspective. To enable these techniques requires the collection and assay of activated target material. In Nov. 2008, experiments were performed using the Omega Laser at the University of Rochester to study the efficiency of collecting debris from directly driven targets. Results from these experiments indicate that target debris was successfully collected, and the debris thermalization and transport scheme enhanced the debris collection up to 347% over direct collection.

  14. Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets.

    PubMed

    Gauthier, P; Chaland, F; Masse, L

    2004-11-01

    By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas. PMID:15600681

  15. Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets.

    PubMed

    Gauthier, P; Chaland, F; Masse, L

    2004-11-01

    By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas.

  16. Deflagration-to-detonation transition in inertial-confinement-fusion baseline targets

    SciTech Connect

    Gauthier, P.; Chaland, F.; Masse, L.

    2004-11-01

    By means of highly resolved one-dimensional hydrodynamics simulations, we provide an understanding of the burn process in inertial-confinement-fusion baseline targets. The cornerstone of the phenomenology of propagating burn in such laser-driven capsules is shown to be the transition from a slow unsteady reaction-diffusion regime of thermonuclear combustion (some sort of deflagration) to a fast detonative one. Remarkably, detonation initiation follows the slowing down of a shockless supersonic reaction wave driven by energy redeposition from the fusion products themselves. Such a route to detonation is specific to fusion plasmas.

  17. Collective excitations of a spherically confined Yukawa plasma

    SciTech Connect

    Kaehlert, H.; Bonitz, M.

    2011-05-15

    The complete spectrum of eigenmodes of a spherically confined Yukawa plasma is presented, based on first-principle molecular dynamics simulations. These results are compared with a recent fluid theory for the multipole modes of this system [H. Kaehlert and M. Bonitz, Phys. Rev. E 82, 036407 (2010)] and with the exact N-particle eigenmodes in the crystalline phase. Simulations confirm the existence of high-order modes found in cold fluid theory. We investigate the influence of screening, coupling, and friction on the mode spectra in detail. Good agreement between theory and simulation is found for weak to moderate screening and low-order modes. In addition, a number of new modes are observed which are missing in the fluid theory. The relations between the breathing mode in the fluid theory, simulation, and the crystal eigenmode are investigated in further detail.

  18. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions.

  19. Anisotropic confinement effects in a two-dimensional plasma crystal.

    PubMed

    Laut, I; Zhdanov, S K; Räth, C; Thomas, H M; Morfill, G E

    2016-01-01

    The spectral asymmetry of the wave-energy distribution of dust particles during mode-coupling-induced melting, observed for the first time in plasma crystals by Couëdel et al. [Phys. Rev. E 89, 053108 (2014)PLEEE81539-375510.1103/PhysRevE.89.053108], is studied theoretically and by molecular-dynamics simulations. It is shown that an anisotropy of the well confining the microparticles selects the directions of preferred particle motion. The observed differences in intensity of waves of opposed directions are explained by a nonvanishing phonon flux. Anisotropic phonon scattering by defects and Umklapp scattering are proposed as possible reasons for the mean phonon flux. PMID:26871180

  20. Simulating the magnetized liner inertial fusion plasma confinement with smaller-scale experiments [Simulating the MagLIF plasma confinement with smaller-scale experiments

    SciTech Connect

    Ryutov, D. D.; Cuneo, M. E.; Herrmann, M. C.; Sinars, D. B.; Slutz, S. A.

    2012-06-20

    The recently proposed magnetized liner inertial fusion approach to a Z-pinch driven fusion [Slutz et al., Phys. Plasmas17, 056303 (2010)] is based on the use of an axial magnetic field to provide plasma thermal insulation from the walls of the imploding liner. The characteristic plasma transport regimes in the proposed approach cover parameter domains that have not been studied yet in either magnetic confinement or inertial confinement experiments. In this article, an analysis is presented of the scalability of the key physical processes that determine the plasma confinement. The dimensionless scaling parameters are identified and conclusion is drawn that the plasma behavior in scaled-down experiments can correctly represent the full-scale plasma, provided these parameters are approximately the same in two systems. Furthermore, this observation is important in that smaller-scale experiments typically have better diagnostic access and more experiments per year are possible.

  1. Why Magnetically Confined Plasmas Rotate and Why it is Important

    NASA Astrophysics Data System (ADS)

    Kaye, Stanley

    2012-03-01

    Rotation in tokamak and spherical tokamak magnetic confinement devices has been found to be critical to enhancing the plasma stability to both the electron and ion gyroradius scale-turbulence as well to magnetohydrodynamic (MHD) modes whose characteristic scales can be of order the device size. Suppression of these modes leads to reduced energy and particle transport losses in these plasmas, thus increasing the potential fusion power production. Rotation can also lead to the avoidance of catastrophic MHD events known as ``disruptions.'' This strong impact of the rotation underscores the importance of developing the knowledge of how rotation is generated in these devices and how the momentum is transported through the plasma. Rotation in these plasmas is generated by a number of different torques, including external momentum input from neutral beam injection, and magnetic torques (toroidal viscosity) resulting from a non-axisymmetric magnetic field structure. One leading theory suggests that rotation can also be self-generated from microturbulence. In this strongly coupled, predator-prey-like system, the plasma can self-organize from a turbulent state to one with directed flow in directions both parallel and perpendicular to the magnetic field. The rotation in the perpendicular direction is often seen to have radial structure and is analogous to the Zonal Flows observed in planetary atmospheres. The self-generated, or intrinsic, rotation that flows mainly along the magnetic field, has been measured on virtually all experimental devices. The theory suggests that the intrinsic torque generating the intrinsic rotation is due to long-wavelength (of order the ion gyroradius) modes, and experimental measurements of intrinsic torque and rotation generally follow the trends predicted by theory. Values of the momentum diffusivity and convective pinch term have been determined from perturbation experiments, and their trends indicate that the same modes that drive intrinsic

  2. Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas

    SciTech Connect

    Hill, K. W.; Bitter, M.; Delgado-Aparacio, L.; Pablant, N. A.; Beiersdorfer, P.; Schneider, M.; Widmann, K.; Sanchez del Rio, M.; Zhang, L.

    2012-10-15

    High resolution ({lambda}/{Delta}{lambda}{approx} 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-{mu}m {sup 55}Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10{sup -8}-10{sup -6} times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

  3. Transmission Grating Imaging Spectrometer for Magnetically Confined Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Blagojevic, B.; Stutman, D.; Vero, R.; Finkenthal, M.; Moos, H. W.

    2001-10-01

    The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating (TG) based imaging spectrometer for the soft and ultrasoft X-ray (USXR) ranges. The spectrometer will be integrated into a multi-purpose impurity diagnostic package for Magnetically Confined Fusion experiments, which will provide time and space resolved information about radiation losses, Zeff profiles and particle transport. The package will also include 2-D filtered USXR diode arrays and atomic physics and impurity transport computational capability. The spectrometer has a very simple layout, consisting of two collimating and space resolving slits, a TG and a 2-D imaging detector. As detector we are developing phosphor (P45) coated fiber optic plates with CCD and intensified CCD image readout. The performance of a test 5000 l/mm, 2:1 bar to open area ratio TG has been evaluated in the laboratory using a K-alpha Manson source and the emission from a Penning Discharge. The incident and diffracted photon flux was recorded in the 10-300 Å range with a gas flow proportional counter. The measurements show that spectral resolution and efficiency agree well with the predicted values. A device optimized for spectral resolution and higher order suppression will be tested on the CDX-U and NSTX tokamak at Princeton Plasma Physics Laboratory. Work supported by DoE grant No. DE-FG02-86ER52314ATDoE

  4. Transport processes in magnetically confined plasmas in the nonlinear regime

    SciTech Connect

    Sonnino, Giorgio

    2006-06-15

    A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate flows combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schlueter regimes are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two regimes. On the other hand, the fluxes of matter and electronic energy (heat flow) is further enhanced in the nonlinear Classical and Pfirsch-Schlueter regimes. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana regime, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.

  5. Heavy ion plasma confinement in an RF quadrupole trap

    NASA Technical Reports Server (NTRS)

    Schermann, J.; Major, F. G.

    1971-01-01

    The confinement of an electron free plasma in a pure quadrupole RF electric trap was considered. The ultimate goal was to produce a large density of mercury ions, in order to realize a trapped ion frequency standard using the hyperfine resonance of 199 Hg(+) at 40.7 GHz. An attempt was made to obtain an iodine plasma consisting of equal numbers of positive and negative ions of atomic iodine, the positive iodine ions, being susceptible to charge-exchange with mercury atoms, will produce the desired mercury ions. The experiment showed that the photoproduction of ions pairs in iodine using the necessary UV radiation occurs with a small cross-section, making it difficult to demonstrate the feasibility of space charge neutralization in a quadrupole trap. For this reason it was considered expedient to choose thallium iodide, which has a more favorable absorption spectrum (in the region of 2000 to 2100 A). The results indicate that, although the ionic recombination is a serious limiting factor, a considerable improvement can be obtained in practice for the density of trapped ions, with a considerable advantage in lifetimes for spectroscopic purposes. The ion pair formation by photoionization is briefly reviewed.

  6. Interaction physics for the shock ignition scheme of inertial confinement fusion targets

    NASA Astrophysics Data System (ADS)

    Depierreux, S.; Goyon, C.; Lewis, K.; Bandulet, H.; Michel, D. T.; Loisel, G.; Yahia, V.; Tassin, V.; Stenz, C.; Borisenko, N. G.; Nazarov, W.; Limpouch, J.; Masson Laborde, P. E.; Loiseau, P.; Casanova, M.; Nicolaï, Ph; Hüller, S.; Pesme, D.; Riconda, C.; Tikhonchuk, V. T.; Labaune, C.

    2011-12-01

    This paper presents an analysis of laser-plasma interaction risks of the shock ignition (SI) scheme and experimental results under conditions relevant to the corona of a compressed target. Experiments are performed on the LIL facility at the 10 kJ level, on the LULI 2000 facility with two beams at the kJ level and on the LULI 6-beam facility with 100 J in each beam. Different aspects of the interaction of the SI pulse are studied exploiting either the flexibility of the LULI 6-beam facility to produce a very high intensity pulse or the high energy of the LIL to produce long and hot plasmas. A continuity is found allowing us to draw some conclusions regarding the coupling quality and efficiency of the SI spike pulse. It is shown that the propagation of the SI beams in the underdense plasma present in the corona of inertial confinement fusion targets could strongly modify the initial spot size of the beam through filamentation. Detailed experimental studies of the growth and saturation of backscattering instabilities in these plasmas indicate that significant levels of stimulated scattering reflectivities (larger than 40%) may be reached at least for some time during the SI pulse.

  7. First results from a soft-x-ray laser experiment in a confined plasma column

    SciTech Connect

    Suckewer, S; Johnson, L C; Sato, K; Semet, A; Skinner, C H; Voorhees, D

    1982-04-01

    We present a description of the experimental set up and the first results from an experiment designed to achieve lasing action in the soft x-ray region of the spectrum. A 0.5 kJ CO/sub 2/ laser was focused into a target gas, typically CO/sub 2/, and the resulting plasma was confined in a 50 to 90 kG magnetic field. Spectroscopic diagnostics were used to monitor the n = 7 and n = 8 level populations of CVI as well as ultraviolet emission lines of CV and CIII, for different plasma conditions. We present data showing that as the confining magnetic field was increased, the plasma column diameter decreased, the CVI 3434 line intensity (7 ..-->.. 6 transition) increased and its decay time decreased consistent with earlier computer modeling. We also discuss the effect of the low intensity tail, normally present in CO/sub 2/ laser pulses, on the predicted population inversion. Analysis of the experimental data by computer simulation shows the range of expected total gain on the n = 3 to n = 2 transition at 182A in these experiments was G = 0.05 to 0.1 and the possibility for its significant increase.

  8. Internal Kink Quasi-Mode in Magnetically Confined Toroidal Plasmas

    NASA Astrophysics Data System (ADS)

    Porcelli, F.; Candy, J.; Breizman, B.; Berk, H.

    1997-11-01

    A well-known instability of magnetically confined plasmas, the internal kink mode, is thought to be responsible for sawtooth relaxations and fishbone oscillations in tokamak discharges. The mode structure is dominated by the (n,m)=(1,1) Fourier harmonic, with a radial structure characterized by a rigid displacement of the plasma core region (where the safety factor is below unity). In standard linear magnetohydrodynamic (MHD) theory, an eigenmode can be obtained only under unstable conditions (dwmhd < 0). When dwmhd > 0, the solution in the q=1 layer cannot by asymptotically matched to the outer region, and so an eigenmode does not exist. In the more general case where energetic particles modify the energy functional via an additive term, dw = dwmhd + dwhot, the standard theory still fails to provide a well-behaved mode structure when Re dw > 0. In this work, we show how to obtain a mode structure that is valid in both stable and unstable conditions by solving a real-time initial value problem. This extension of the standard linear theory of internal kinks is especially desirable with regard to the development of nonlinear models of the fishbone instability, which attempt to simulate a full fishbone burst. We refer to the internal kink profile that is obtained under stable conditions as a quasi-mode, in view of the fact that the space and time dependences cannot be separated.

  9. Taming Magnetically Confined Plasmas with RF Waves: A Historical Perspective

    NASA Astrophysics Data System (ADS)

    Porkolab, Miklos

    2009-11-01

    Heating and profile control by RF waves in magnetic fusion experiments has led to the development of a new area of physics, namely wave propagation and absorption in high temperature plasmas in complex magnetic field geometries. In addition, the development of high power microwave sources as well as novel antenna structures capable of handling high RF powers has also been necessary. In this talk I shall summarize the historical progression of relevant results in three frequency regimes, namely the ion cyclotron range of frequencies (ICRF), the electron cyclotron frequency and its harmonics (ECRH), and the lower hybrid frequency range (LHRF). In the ICRF regime breakthrough heating results were obtained in the 1980s in tokamaks with good confinement of energetic ions, such as PLT, TFTR and JET. In the period of late 1970s to mid 1980s the theory of RF current drive (LHCD, ECCD and that of fast wave, or FWCD) was developed. Soon thereafter efficient lower hybrid current drive was demonstrated in tokamak experiments such as Versator II, Alcator--C and PLT, and later JT60-U, Tore-Supra and JET. High harmonic FWCD has been also demonstrated on DIII-D and NSTX. Long pulse multi-MW LHCD experiments are now in preparation on the new superconducting tokamaks EAST (China) and K-STAR (Korea). ECRH results in the 1980s and beyond progressed rapidly with the development of gyrotron sources at the MW level and subsequently efficient heating and current drive was demonstrated on DIII-D, Asdex-U, JT-60U and TCV, including the stabilization of neoclassical tearing modes. Recent gyrotron tube development at the MW level at 170 GHz ensures the availability of ECH and ECCD on ITER. Finally, new results on RF induced transport phenomena have been discovered, such as enhanced plasma rotation and flow drive that hold promise for optimizing ITER performance.

  10. Composite Transport Coefficients and Novel Scalings for Well Confined Plasmas

    NASA Astrophysics Data System (ADS)

    Coppi, B.; Daughton, W.

    1997-11-01

    Starting from an analysis of the transport properties of the plasmas produced by the Alcator C-Mod machine over a rather wide variety of conditions, a novel form of a thermal transport coefficient which reproduces both ohmic and auxiliary heated L-mode discharges [1] has been identified. This coefficient involves the difference of two terms, one representing the normal outward diffusion of thermal energy and the other corresponding to a process reducing the outward flux. There are in fact theoretical arguments [2] in support of a composite transport coefficient based on the symmetry properties of an appropriate transport matrix. The relevant scaling for the energy confinement time is also composed of two terms and the L-mode database including D3D, JET, JT60, PDX, TFTR, FTU, Alcator C-Mod is used to construct a general scaling law that is shown to be more comprehensive and accurate than the standard L-mode scaling, particularly for high field experiments. [1] B. Coppi A. Airoldi, F. Bombarda et al., IAEA Conference, F1-CN-64/BP-14 (1996) [2] B. Coppi and F. Pegoraro, Phys. Fluids B 3 2582 (1991)

  11. Improvement of confinement times of lithium ion and electron plasmas in BX-U

    SciTech Connect

    Himura, H.; Noichi, T.; Nakata, S.; Kawai, S.; Sanpei, A.

    2015-06-29

    Confinements of both electron (e{sup −}) and Lithium ion (Li{sup +}) plasmas in the BX-U machine are improved experimentally. For the e{sup −} plasma, the longest confinement time so far has been ∼ 10 s, which is much longer than the classical electron-electron collision time: τ{sub ee} ∼ 0.6 s. On the other hand, for the Li{sup +} plasma, the longest confinement time has been about 0.5 s, which is still much shorter than the classical ion-ion collision time.

  12. Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Simakov, Andrei N.; Wilson, Douglas C.; Yi, Sunghwan A.; Kline, John L.; Clark, Daniel S.; Milovich, Jose L.; Salmonson, Jay D.; Batha, Steven H.

    2014-02-01

    For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer.

  13. Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

    SciTech Connect

    Simakov, Andrei N. Wilson, Douglas C.; Yi, Sunghwan A.; Kline, John L.; Batha, Steven H.; Clark, Daniel S.; Milovich, Jose L.; Salmonson, Jay D.

    2014-02-15

    For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer.

  14. Spectrometry of charged particles from inertial-confinement-fusion plasmas

    NASA Astrophysics Data System (ADS)

    Séguin, F. H.; Frenje, J. A.; Li, C. K.; Hicks, D. G.; Kurebayashi, S.; Rygg, J. R.; Schwartz, B.-E.; Petrasso, R. D.; Roberts, S.; Soures, J. M.; Meyerhofer, D. D.; Sangster, T. C.; Knauer, J. P.; Sorce, C.; Glebov, V. Yu.; Stoeckl, C.; Phillips, T. W.; Leeper, R. J.; Fletcher, K.; Padalino, S.

    2003-02-01

    High-resolution spectrometry of charged particles from inertial-confinement-fusion (ICF) experiments has become an important method of studying plasma conditions in laser-compressed capsules. In experiments at the 60-beam OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], utilizing capsules with D2, D3He, DT, or DTH fuel in a shell of plastic, glass, or D2 ice, we now routinely make spectral measurements of primary fusion products (p, D, T, 3He, α), secondary fusion products (p), "knock-on" particles (p, D, T) elastically scattered by primary neutrons, and ions from the shell. Use is made of several types of spectrometers that rely on detection and identification of particles with CR-39 nuclear track detectors in conjunction with magnets and/or special ranging filters. CR-39 is especially useful because of its insensitivity to electromagnetic noise and its ability to distinguish the types and energies of individual particles, as illustrated here by detailed calibrations of its response to 0.1-13.8 MeV protons from a Van de Graaff accelerator and to p, D, T, and α from ICF experiments at OMEGA. A description of the spectrometers is accompanied by illustrations of their operating principles using data from OMEGA. Sample results and discussions illustrate the relationship of secondary-proton and knock-on spectra to capsule fuel and shell areal densities and radial compression ratios; the relationship of different primary fusion products to each other and to ion temperatures; the relationship of deviations from spherical symmetry in particle yields and energies to capsule structure; the acceleration of fusion products and the spectra of ions from the shell due to external fields; and other important physical characteristics of the laser-compressed capsules.

  15. Magnetized Target Fusion Driven by Plasma Liners

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Cassibry, Jason; Eskridge, Richard; Kirkpatrick, Ronald C.; Knapp, Charles E.; Lee, Michael; Martin, Adam; Smith, James; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    For practical applications of magnetized target fusion, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Quasi-spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a quasi-spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC). Theoretical analysis and computer modeling of the concept are presented. It is shown that, with the appropriate choice of the flow parameters in the liner and the target, the impact between the liner and the target plasma can be made to be shockless in the liner or to generate at most a very weak shock in the liner. Additional information is contained in the original extended abstract.

  16. Simulating the magnetized liner inertial fusion plasma confinement with smaller-scale experiments

    SciTech Connect

    Ryutov, D. D.; Cuneo, M. E.; Herrmann, M. C.; Sinars, D. B.; Slutz, S. A.

    2012-06-15

    The recently proposed magnetized liner inertial fusion approach to a Z-pinch driven fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010)] is based on the use of an axial magnetic field to provide plasma thermal insulation from the walls of the imploding liner. The characteristic plasma transport regimes in the proposed approach cover parameter domains that have not been studied yet in either magnetic confinement or inertial confinement experiments. In this article, an analysis is presented of the scalability of the key physical processes that determine the plasma confinement. The dimensionless scaling parameters are identified and conclusion is drawn that the plasma behavior in scaled-down experiments can correctly represent the full-scale plasma, provided these parameters are approximately the same in two systems. This observation is important in that smaller-scale experiments typically have better diagnostic access and more experiments per year are possible.

  17. System and method for generating steady state confining current for a toroidal plasma fusion reactor

    DOEpatents

    Bers, Abraham

    1981-01-01

    A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to estalish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated inthe plasma.

  18. System and method for generating steady state confining current for a toroidal plasma fusion reactor

    DOEpatents

    Fisch, Nathaniel J.

    1981-01-01

    A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to establish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated in the plasma.

  19. Observation of Centrifugally Driven Interchange Instabilities in a Plasma Confined by a Magnetic Dipole

    SciTech Connect

    Levitt, B.; Maslovsky, D.; Mauel, M.E.

    2005-05-06

    Centrifugally driven interchange instabilities are observed in a laboratory plasma confined by a dipole magnetic field. The instabilities appear when an equatorial mesh is biased to drive a radial current that causes rapid axisymmetric plasma rotation. The observed instabilities are quasicoherent in the laboratory frame of reference; they have global radial mode structures and low azimuthal mode numbers, and they are modified by the presence of energetic, magnetically confined electrons. Results from a self-consistent nonlinear simulation reproduce the measured mode structures.

  20. Numerical study of the irradiation uniformity of a directly driven inertial confinement fusion target

    NASA Astrophysics Data System (ADS)

    Temporal, M.; Canaud, B.; Laffite, S.; Le Garrec, B. J.; Murakami, M.

    2010-11-01

    In the Inertial Confinement Fusion the uniformity of the irradiation still represents a crucial issue. In this context a spherical capsule directly driven by laser beams have been assessed numerically [1]. Two schemes characterized by 32 and 48 directions of irradiation [2] with associated a single laser beam or a bundle of laser beams [3] characterized by a super-Gaussian intensity profile are considered. Beam imperfections as power imbalance and pointing errors have been taken into account. It is found that the focal spot that minimizes the rms deviation depends on the beam imperfections [4]. The numerical calculations show that the uniformity of the irradiation evolves in time. The results calculated considering the illumination of a spherical target will be compared with those obtained when the irradiation is taken into account. [1] M. Temporal, B. Canaud. Eur. Phys. J. D 55 139 (2009). [2] M. Murakami, N. Sarukura, H. Azechi, M. Temporal, A.J. Schmitt, in press to Phys. Plasmas (July issue, 2010). [3] M. Temporal, B. Canaud, B. J. Le Garrec, Phys. Plasmas 17 022701 (2010). [4] M. Temporal, B. Canaud, S. Laffite, B.J. Le Garrec, M. Murakami. Phys. Plasmas 17 064504 (2010).

  1. The potential role of electric fields and plasma barodiffusion on the inertial confinement fusion databasea)

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Wilks, S. C.; Bellei, C.; Li, C. K.; Petrasso, R. D.

    2011-05-01

    The generation of strong, self-generated electric fields (GV/m) in direct-drive, inertial-confinement-fusion (ICF) capsules has been reported [Rygg et al., Science 319, 1223 (2008); Li et al., Phys. Rev. Lett. 100, 225001 (2008)]. A candidate explanation for the origin of these fields based on charge separation across a plasma shock front was recently proposed [Amendt et al., Plasma Phys. Controlled Fusion 51 124048 (2009)]. The question arises whether such electric fields in imploding capsules can have observable consequences on target performance. Two well-known anomalies come to mind: (1) an observed ≈2× greater-than-expected deficit of neutrons in an equimolar D3He fuel mixture compared with hydrodynamically equivalent D [Rygg et al., Phys. Plasmas 13, 052702 (2006)] and DT [Herrmann et al., Phys. Plasmas 16, 056312 (2009)] fuels, and (2) a similar shortfall of neutrons when trace amounts of argon are mixed with D in indirect-drive implosions [Lindl et al., Phys. Plasmas 11, 339 (2004)]. A new mechanism based on barodiffusion (or pressure gradient-driven diffusion) in a plasma is proposed that incorporates the presence of shock-generated electric fields to explain the reported anomalies. For implosions performed at the Omega laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)], the (low Mach number) return shock has an appreciable scale length over which the lighter D ions can diffuse away from fuel center. The depletion of D fuel is estimated and found to lead to a corresponding reduction in neutrons, consistent with the anomalies observed in experiments for both argon-doped D fuels and D3He equimolar mixtures. The reverse diffusional flux of the heavier ions toward fuel center also increases the pressure from a concomitant increase in electron number density, resulting in lower stagnation pressures and larger imploded cores in agreement with gated, self-emission, x-ray imaging data.

  2. Debye Layers in Plasmas Generalized to Hadron Confinement of Nuclei and Quark-Gluon-Plasmas

    NASA Astrophysics Data System (ADS)

    Hora, Heinrich; Miley, George H.

    2005-10-01

    . A new theory for the nuclear forces for confining the hadrons in a nucleus has been derived from a generalization of the Debye layer as known from the plasma ablation at laser irradiation where the temperature is substituted by the Fermi energy of the nucleons [1]. The first convincing proof is by using the empirical density of the nucleons defining their Fermi energy to arrive at a Debye length of about 3 fm as measured by Hofstadter for the decay of the nucleon density at the surface of heavy nuclei. This decay is interpreted as Wigner scattering and the Goos-Haenchen effect. With the same steps of substitutions, the surface energy of nuclei is always too small against the nucleon enthalpy to confine the hadrons until the density reaches such high values reproducing the empirical known radii of nuclei. By this way nuclei are possible only until uranium or curium by a Boltzmann equilibrium process explaining the endothermic generation of heavy nuclei in the Universe [2]. At and about six times higher nucleon density, the Fermi statistics changes into its relativistic branch excluding nucleation in neutron stars and explaining the quark-gluon plasma. [1] Edward Teller Lectures, H. Hora and G.H. Miley eds. (Imperial College Press London 2005) p. 103. [2] H. Hora, G.H. Miley, F. Osman, Astrophysics and Space Science, 298, 247 (2005)

  3. Plasma Confinement in Glass Microcavities: Dependence of Plasma Properties on Microcavity Geometry.

    NASA Astrophysics Data System (ADS)

    Sung, S. H.; Berger, A. G.; Kim, J.-Y.; Park, S.-J.; Eden, J. G.

    2007-10-01

    Arrays of glass microcavities having diameters of 50-200 μm and controllable geometries have been successfully fabricated by micropowder blasting techniques. Anisotropic or isotropic microcavities, including cavities with ellipsoidal geometry have been fabricated in large scale arrays with high resolution and various shapes of microcavities were prepared precisely. Arrays having as much as 1000 microcavities were fabricated on 400 μm thick soda lime glasses and a pair of these glasses was aligned and sealed to form a closed microdischarge cell. The cross-sectional microcavity shape in the discharge cell is designed from the calculation of electric field distribution. Powered by electrodes located outside the microcavity with ac frequencies of 20-100 kHz, the stable, uniform discharges and confinement of plasma in entire microcavity was observed at 300-800 Torr of noble gases. From the spatially-resolved measurement of emission from a microcavity, the device has better plasma confinement and increased emission intensity in higher gas pressures. Discharge performance in various gas or gas mixtures and its dependence on microcavity geometry will be discussed.

  4. Studies of plasma confinement in linear and RACETRACK mirror configurations

    SciTech Connect

    Kuthi, A.; Wong, A.Y.

    1986-06-30

    This report discusses research on the following magnetic mirror configurations: Racetrack; ECRH generated plasmas; RF generated plasmas; potential structures; surface multipole fields, and lamex; hot electron physics; axial loss processes; and RF induced effects.

  5. Influence of scrape-off layer on plasma confinement

    SciTech Connect

    Dolan, Thomas J.

    2011-03-15

    The purpose of this paper is to discuss how plasma phenomena in the scrape-off layer (SOL) can affect the plasma density gradient at the separatrix and hence the plasma behavior inside the separatrix. The parallel flow loss rate and ionization rate in the SOL (related to the electron temperature and neutral gas density) affect the curvature of the electron density profile, which limits the density gradient at the separatrix. This density gradient acts like a boundary condition for plasma inside the separatrix, affecting the ion pressure gradient, radial electric field, and plasma behavior.

  6. Ion confinement and transport in a toroidal plasma with externally imposed radial electric fields

    NASA Technical Reports Server (NTRS)

    Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Kim, Y. C.; Hong, H. Y.

    1979-01-01

    Strong electric fields were imposed along the minor radius of the toroidal plasma by biasing it with electrodes maintained at kilovolt potentials. Coherent, low-frequency disturbances characteristic of various magnetohydrodynamic instabilities were absent in the high-density, well-confined regime. High, direct-current radial electric fields with magnitudes up to 135 volts per centimeter penetrated inward to at least one-half the plasma radius. When the electric field pointed radially toward, the ion transport was inward against a strong local density gradient; and the plasma density and confinement time were significantly enhanced. The radial transport along the electric field appeared to be consistent with fluctuation-induced transport. With negative electrode polarity the particle confinement was consistent with a balance of two processes: a radial infusion of ions, in those sectors of the plasma not containing electrodes, that resulted from the radially inward fields; and ion losses to the electrodes, each of the which acted as a sink and drew ions out of the plasma. A simple model of particle confinement was proposed in which the particle confinement time is proportional to the plasma volume. The scaling predicted by this model was consistent with experimental measurements.

  7. Two-Plasmon Decay Mitigation in Direct-Drive Inertial-Confinement-Fusion Experiments Using Multilayer Targets

    NASA Astrophysics Data System (ADS)

    Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; Goncharov, V. N.; Henchen, R. J.; Katz, J.; Michel, D. T.; Myatt, J. F.; Shaw, J.; Solodov, A. A.; Stoeckl, C.; Yaakobi, B.; Froula, D. H.

    2016-04-01

    Multilayer direct-drive inertial-confinement-fusion targets are shown to significantly reduce two-plasmon decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor-of-5 reduction in hot-electron generation (>50 keV ) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD-driven hot-electron production using a laser-plasma interaction code (lpse) that includes nonlinear and kinetic effects show good agreement with the measurements. The simulations suggest that the reduction in hot-electron production observed in the multilayer targets is primarily caused by increased electron-ion collisional damping.

  8. Two-plasmon decay mitigation in direct-drive inertial-confinement-fusion experiments using multilayer targets

    DOE PAGESBeta

    Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; Goncharov, V. N.; Henchen, R. J.; Katz, J.; Michel, D. T.; Myatt, J. F.; Shaw, J.; Solodov, A. A.; et al

    2016-04-15

    Multilayer direct-drive inertial-confinement-fusion (ICF) targets are shown to significantly reduce two-plasmon-decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA Laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor of five reduction in hot-electron generation (> 50 keV) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD driven hot-electron production using a laser-plasma interaction code (LPSE) that includes nonlinear and kinetic effects show excellent agreement with the measurements. As a result, the simulations suggest that the reduction in hot-electron productionmore » observed in the multilayer targets is primarily due to increased electron-ion collisional damping.« less

  9. Two-Plasmon Decay Mitigation in Direct-Drive Inertial-Confinement-Fusion Experiments Using Multilayer Targets.

    PubMed

    Follett, R K; Delettrez, J A; Edgell, D H; Goncharov, V N; Henchen, R J; Katz, J; Michel, D T; Myatt, J F; Shaw, J; Solodov, A A; Stoeckl, C; Yaakobi, B; Froula, D H

    2016-04-15

    Multilayer direct-drive inertial-confinement-fusion targets are shown to significantly reduce two-plasmon decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor-of-5 reduction in hot-electron generation (>50  keV) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD-driven hot-electron production using a laser-plasma interaction code (lpse) that includes nonlinear and kinetic effects show good agreement with the measurements. The simulations suggest that the reduction in hot-electron production observed in the multilayer targets is primarily caused by increased electron-ion collisional damping. PMID:27127973

  10. MAGNETIC END CLOSURES FOR PLASMA CONFINING AND HEATING DEVICES

    DOEpatents

    Post, R.F.

    1963-08-20

    More effective magnetic closure field regions for various open-ended containment magnetic fields used in fusion reactor devices are provided by several spaced, coaxially-aligned solenoids utilized to produce a series of nodal field regions of uniform or, preferably, of incrementally increasing intensity separated by lower intensity regions outwardly from the ends of said containment zone. Plasma sources may also be provided to inject plasma into said lower intensity areas to increase plasma density therein. Plasma may then be transported, by plasma diffusion mechanisms provided by the nodal fields, into the containment field. With correlated plasma densities and nodal field spacings approximating the mean free partl cle collision path length in the zones between the nodal fields, optimum closure effectiveness is obtained. (AEC)

  11. APPARATUS FOR MINIMIZING ENERGY LOSSES FROM MAGNETICALLY CONFINED VOLUMES OF HOT PLASMA

    DOEpatents

    Post, R.F.

    1961-10-01

    An apparatus is described for controlling electron temperature in plasma confined in a Pyrotron magnetic containment field. Basically the device comprises means for directing low temperature electrons to the plasma in controlled quantities to maintain a predetermined optimum equilibrium electron temperature whereat minimum losses of plasma ions due to ambipolar effects and energy damping of the ions due to dynamical friction with the electrons occur. (AEC)

  12. Pure electron plasmas confined for 90 ms in a stellarator without electron sources or internal objects

    SciTech Connect

    Brenner, P. W.; Sunn Pedersen, T.

    2012-05-15

    We report on the creation and up to 90 ms sustainment of pure electron plasmas confined in a stellarator without internal objects. Injection of positrons into such plasmas is expected to lead to the creation of the first electron-positron plasma experiments. These newly created plasmas will also allow a study of pure electron plasmas without the perturbing presence of internal objects. The plasmas were created by thermionic emission of electrons from a heated, biased filament that was retracted in 20 ms. The confinement of these transient plasmas is different from that of steady state plasmas with internal objects and emissive filaments, and is generally shorter, limited by ion buildup. The decay time is increased by lowering the neutral pressure, lowering the electron plasma temperature, or operating with neutrals with high ionization energies (helium). These findings are all consistent with ion accumulation being the cause for the shorter than expected confinement times. The magnetic field strength also moderately increases the decay times. The deleterious effect of ions is not expected to imply a similar deleterious effect when introducing positrons, but it implies that ion accumulation must be avoided also in an electron-positron experiment.

  13. Spherical fusion plasma-confinement field of Surmac type

    SciTech Connect

    Wipf, S.L.

    1981-01-01

    The concept of a Surmac confinement field that can be completely closed is presented. The internal conductor is magnetically suspended inside large corrugations of a superconducting spherical shell structure that carries the return current. Presently available superconductor technology using superfluid helium cooling allows fields above 1.5T throughout the wall region. Such a Surmac has potential for the study of advanced fuel cycles.

  14. Simulations of plasma confinement in an antihydrogen trap

    SciTech Connect

    Gomberoff, K.; Fajans, J.; Friedman, A.; Grote, D.; Vay, J.-L.; Wurtele, J.S.

    2007-10-15

    The three-dimensional particle-in-cell (3-D PIC) simulation code WARP is used to study positron confinement in antihydrogen traps. The magnetic geometry is close to that of a UC Berkeley experiment conducted, with electrons, as part of the ALPHA collaboration (W. Bertsche et al., AIP Conf. Proc. 796, 301 (2005)). In order to trap antihydrogen atoms, multipole magnetic fields are added to a conventional Malmberg-Penning trap. These multipole fields must be strong enough to confine the antihydrogen, leading to multipole field strengths at the trap wall comparable to those of the axial magnetic field. Numerical simulations reported here confirm recent experimental measurements of reduced particle confinement when a quadrupole field is added to a Malmberg-Penning trap. It is shown that, for parameters relevant to various antihydrogen experiments, the use of an octupole field significantly reducesthe positron losses seen with a quadrupole field. A unique method for obtaining a 3-D equilibrium of the positrons in the trap with a collisionless PIC code was developed especially for the study of the antihydrogen trap; however, it is of practical use for other traps as well.

  15. Simulations of plasma confinement in an antihydrogen trap

    SciTech Connect

    Gomberoff, K.; Fajans, J.; Friedman, A.; Grote, D.; Vay, J.-L.; Wurtele, J. S.

    2007-10-15

    The three-dimensional particle-in-cell (3-D PIC) simulation code WARP is used to study positron confinement in antihydrogen traps. The magnetic geometry is close to that of a UC Berkeley experiment conducted, with electrons, as part of the ALPHA collaboration [W. Bertsche et al., AIP Conf. Proc. 796, 301 (2005)]. In order to trap antihydrogen atoms, multipole magnetic fields are added to a conventional Malmberg-Penning trap. These multipole fields must be strong enough to confine the antihydrogen, leading to multipole field strengths at the trap wall comparable to those of the axial magnetic field. Numerical simulations reported here confirm recent experimental measurements of reduced particle confinement when a quadrupole field is added to a Malmberg-Penning trap. It is shown that, for parameters relevant to various antihydrogen experiments, the use of an octupole field significantly reduces the positron losses seen with a quadrupole field. A unique method for obtaining a 3-D equilibrium of the positrons in the trap with a collisionless PIC code was developed especially for the study of the antihydrogen trap; however, it is of practical use for other traps as well.

  16. Impurity accumulation in plasma regimes with high energy confinement

    NASA Astrophysics Data System (ADS)

    Ran, L. B.; Roberts, D. E.; Yang, H. R.; Dodel, G.; Gentle, K.; Von Goeler, S.; Holzhauer, E.; Hübner, K.; Keilhacker, M.; Korotkov, A.; Luce, T. C.; Miura, Y.; Tsois, N.; Würz, H.; Fussmann, G.; Hofmann, J.; Janeschitz, G.; Krieger, K.; Müller, E. R.; Nolte, R.; Röhr, H.; Steuer, K. H.; Becker, G.; Bomba, B.; Bruhns, H.; Büchl, K.; Carlson, A.; Eberhagen, A.; Fahrbach, H.-U.; Gehre, O.; Gernhardt, J.; Giannone, L.; Von Gierke, G.; Glock, E.; Gruber, O.; Haas, G.; Herrmann, H.; Kaesdorf, S.; Karger, F.; Kaufmann, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lang, R.; Lee, P.; Lisitano, G.; Mast, F.; Mayer, H. M.; McCormick, K.; Meisel, D.; Mertens, V.; Murmann, H.; Neuhauser, J.; Niedermeyer, H.; Noterdaeme, J. M.; Poschenrieder, W.; Preis, R.; Rapp, H.; Rudyj, A.; Sandmann, W.; Schneider, F.; Schnider, U.; Siller, G.; Simmet, E.; Speth, E.; Söldner, F.; Stäbler, A.; Steinmetz, K.; Stroth, U.; Vollmer, O.; Zasche, D.

    1989-04-01

    Investigations of impurity accumulation phenomena in ASDEX are reviewed. There are four different operating regimes where pronounced accumulation is observed and these regimes are also characterized by improved energy confinement. In particular, medium-Z metallic ions are involved in accumulation processes whereas low-Z ions appear almost unaffected. The rapid accumulation observed in the case of metallic ions may be explained by neoclassical inward drifts if we assume that the anomalous diffusion is sufficiently suppressed, some indication of this being found from laser blow-off studies. The present results, however, can only be partly explained by neoclassical theory, according to which accumulation of low-Z impurities should also occur. The temporal behaviour of accumulation and the retarding effect of proton dilution for collision dominated transport are also discussed. Finally, we conclude that the full benefits of improved energy confinement can be achieved only if the impurity influxes are kept to a sufficiently low level. Expressed in terms of concentrations under low confinement conditions we have to postulate, for ASDEX, concentrations ≲ 10 -4 for metals and ≲ 2% for all light impurities.

  17. Complex Plasmas in Narrow Channels: Impact of Confinement on the Local Order

    SciTech Connect

    Klumov, B. A.

    2008-10-15

    Two-dimensional (2D) and three-dimensional (3D) quasi-equilibrium configurations of a complex (dusty) plasma in narrow channels are investigated using the molecular dynamics simulations for various confining potentials (confinements). The dynamics of the microparticles is described within the framework of a Langevin thermostat with allowance for the pair interaction between charged particles, which is described by a screened Coulomb potential (Yukawa potential). Two types of confinement: the parabolic electrostatic potential and hard elastic wall are considered. It is shown that the confinement strongly affects the crystallization and the local order of the microparticles in the system under consideration; in particular, the appearance of a new quasicrystalline phase induced by the hard wall confinement is revealed in 3D case.

  18. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl

    2003-12-16

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  19. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-03-21

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  20. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-10-10

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  1. Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2008-10-21

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  2. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2007-02-20

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  3. Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma

    DOEpatents

    Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

    2006-02-07

    A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

  4. External Heat Transfer Coefficient Measurements on a Surrogate Indirect Inertial Confinement Fusion Target

    SciTech Connect

    Miles, Robin; Havstad, Mark; LeBlanc, Mary; Golosker, Ilya; Chang, Allan; Rosso, Paul

    2015-09-15

    External heat transfer coefficients were measured around a surrogate Indirect inertial confinement fusion (ICF) based on the Laser Inertial Fusion Energy (LIFE) design target to validate thermal models of the LIFE target during flight through a fusion chamber. Results indicate that heat transfer coefficients for this target 25-50 W/m2∙K are consistent with theoretically derived heat transfer coefficients and valid for use in calculation of target heating during flight through a fusion chamber.

  5. External Heat Transfer Coefficient Measurements on a Surrogate Indirect Inertial Confinement Fusion Target

    DOE PAGESBeta

    Miles, Robin; Havstad, Mark; LeBlanc, Mary; Golosker, Ilya; Chang, Allan; Rosso, Paul

    2015-09-15

    External heat transfer coefficients were measured around a surrogate Indirect inertial confinement fusion (ICF) based on the Laser Inertial Fusion Energy (LIFE) design target to validate thermal models of the LIFE target during flight through a fusion chamber. Results indicate that heat transfer coefficients for this target 25-50 W/m2∙K are consistent with theoretically derived heat transfer coefficients and valid for use in calculation of target heating during flight through a fusion chamber.

  6. Overview of Spontaneous Frequency Chirping in Confined Plasmas

    NASA Astrophysics Data System (ADS)

    Berk, Herbert

    2012-10-01

    Spontaneous rapid frequency chirping is now a commonly observed phenomenon in plasmas with an energetic particle component. These particles typically induce so called weak instabilities, where they excite background waves that the plasma can support such as shear Alfven waves. The explanation for this phenomenon attributes the frequency chirping to the formation of phase space structures in the form of holes and clumps. Normally a saturated mode, in the presence of background dissipation, would be expected decay after saturation as the background plasma absorbs the energy of the excited wave. However the phase space structures take an alternate route, and move to a regions of phase space that are lower energy states of the energetic particle distribution. Through the wave-resonant particle interaction, this movement is locked to the frequency observed by the wave. This phenomenon implies that alternate mechanisms for plasma relaxation need to be considered for plasma states new marginal stability. It is also possible that these chirping mechanisms can be used to advantage to externally control states of plasma.

  7. Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions

    NASA Astrophysics Data System (ADS)

    Basse, N. P.; Zoletnik, S.; Michelsen, P. K.; W7-As Team

    2005-01-01

    Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100μs, similar to the lifetime observed during edge localized modes.

  8. Study of intermittent small-scale turbulence in Wendelstein 7-AS plasmas during controlled confinement transitions

    SciTech Connect

    Basse, N.P.; Zoletnik, S.; Michelsen, P.K.

    2005-01-01

    Confinement transitions in the Wendelstein 7-AS stellarator [H. Renner et al., Plasma Phys. Controlled Fusion 31, 1579 (1989)] can be induced by varying either the internal plasma current or the external magnetic field. In this paper we report on experiments where closely matched confinement states (good and bad) were constructed using the latter method. Analysis using the former scheme has been reported upon previously [S. Zoletnik et al., Plasma Phys. Controlled Fusion 44, 1581 (2002)]. The electron temperature, along with the major spectral characteristics of magnetic and small-scale electron density fluctuations, changes dramatically at the transition from good to bad confinement. The fluctuation power is intermittent, and core bursts traveling in the electron diamagnetic drift (DD) direction are correlated between the bottom and top of the plasma, especially during degraded confinement. A corresponding top-bottom correlation for the edge ion DD direction turbulence feature was not found. Strong correlations are observed both between the two density fluctuation signals and between magnetic and density fluctuations in bad compared to good confinement. The correlation time of the bursts is of order 100 {mu}s, similar to the lifetime observed during edge localized modes.

  9. Formation of high-{beta} plasma and stable confinement of toroidal electron plasma in Ring Trap 1

    SciTech Connect

    Saitoh, H.; Yoshida, Z.; Morikawa, J.; Furukawa, M.; Yano, Y.; Kawai, Y.; Kobayashi, M.; Vogel, G.; Mikami, H.

    2011-05-15

    Formation of high-{beta} electron cyclotron resonance heating plasma and stable confinement of pure electron plasma have been realized in the Ring Trap 1 device, a magnetospheric configuration generated by a levitated dipole field magnet. The effects of coil levitation resulted in drastic improvements of the confinement properties, and the maximum local {beta} value has exceeded 70%. Hot electrons are major component of electron populations, and its particle confinement time is 0.5 s. Plasma has a peaked density profile in strong field region [H. Saitoh et al., 23rd IAEA Fusion Energy Conference EXC/9-4Rb (2010)]. In pure electron plasma experiment, inward particle diffusion is realized, and electrons are stably trapped for more than 300 s. When the plasma is in turbulent state during beam injection, plasma flow has a shear, which activates the diocotron (Kelvin-Helmholtz) instability. The canonical angular momentum of the particle is not conserved in this phase, realizing the radial diffusion of charged particles across closed magnetic surfaces. [Z. Yoshida et al., Phys Rev. Lett. 104, 235004 (2010); H. Saitoh et al., Phys. Plasmas 17, 112111 (2010).].

  10. Double-shell inertial confinement fusion target fabrication

    SciTech Connect

    Hatcher, C.W.; Lorensen, L.E.; Weinstein, B.W.

    1980-08-26

    First generation hemishells, from which spherical shells are constructed, were fabricated by micromachining coated mandrels and by molding. The remachining of coated mandrels are described in detail. Techniques were developed for coating the microsized mandrels with polymeric and metallic materials by methods including conformal coating, vapor deposition, plasma polymerization and thermoforming. Micropositioning equipment and bonding techniques have also been developed to assemble the hemishells about a fuel pellet maintaining a spherical concentricity of better than 2 ..mu..m and voids in the hemishell bonding line of a few hundred angstroms or less.

  11. First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications.

    PubMed

    Hu, S X; Collins, L A; Boehly, T R; Kress, J D; Goncharov, V N; Skupsky, S

    2014-04-01

    Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ∼20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the

  12. First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Collins, L. A.; Boehly, T. R.; Kress, J. D.; Goncharov, V. N.; Skupsky, S.

    2014-04-01

    Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ˜20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the

  13. Convective plasma stability consistent with MHD equilibrium in magnetic confinement systems with a decreasing field

    SciTech Connect

    Tsventoukh, M. M.

    2010-10-15

    A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as {beta} {approx} 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field

  14. Energy Confinement of High-Density Pellet-Fueled Plasmas in the Alcator C Tokamak

    NASA Astrophysics Data System (ADS)

    Greenwald, M.; Gwinn, D.; Milora, S.; Parker, J.; Parker, R.; Wolfe, S.; Besen, M.; Camacho, F.; Fairfax, S.; Fiore, C.; Foord, M.; Gandy, R.; Gomez, C.; Granetz, R.; Labombard, B.; Lipschultz, B.; Lloyd, B.; Marmar, E.; McCool, S.; Pappas, D.; Petrasso, R.; Pribyl, P.; Rice, J.; Schuresko, D.; Takase, Y.; Terry, J.; Watterson, R.

    1984-07-01

    A series of pellet-fueling experiments has been carried out on the Alcator C tokamak. High-speed hydrogen pellets penetrate to within a few centimeters of the magnetic axis, raise the plasma density, and produce peaked density profiles. Energy confinement is observed to increase over similar discharges fueled only by gas puffing. In this manner record values of electron density, plasma pressure, and Lawson number (n τ) have been achieved.

  15. Characterization of the Horizontal Confinement Produced by a Glass Box in a Complex Plasma

    NASA Astrophysics Data System (ADS)

    Bradshaw, Jace; Douglass, Angela

    2013-10-01

    The majority of plasmas in the visible universe are complex plasmas, consisting of not only electrons, ions, and neutral particles, but also small, usually micron-sized particles called ``dust.'' Recent complex plasma experiments have placed a glass box on the lower electrode of a GEC RF reference cell in order to alter the electric confinement experienced by micrometer-sized particles in the plasma. While this has led to interesting observations, such as vertical chains and Coulomb balls, the nature of the confinement is not well understood. In this experiment, a single melamine formaldehyde dust particle was levitated in the plasma sheath and contained by a glass box. The dust particle was then struck by a laser pulse to perturb the particle from its equilibrium position. The trajectory of the particle was analyzed to determine the nature of the electric potential produced by the walls of the glass box. Trials were run with varying pressures, particle sizes, box sizes, and plasma powers to determine the effect of each parameter on the confinement.

  16. Production and study of high-beta plasma confined by a superconducting dipole magnet

    SciTech Connect

    Garnier, D.T.; Hansen, A.; Mauel, M.E.; Ortiz, E.; Boxer, A.C.; Ellsworth, J.; Karim, I.; Kesner, J.; Mahar, S.; Roach, A.

    2006-05-15

    The Levitated Dipole Experiment (LDX) [J. Kesner et al., in Fusion Energy 1998, 1165 (1999)] 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, magnetohydrodynamic 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 ({beta}>1), and the absence of magnetic shear allows particle and energy confinement to decouple. In initial experiments, long-pulse, quasi-steady-state microwave discharges lasting more than 10 s have been produced that are consistent with equilibria having peak beta values of 20%. 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. The plasma is created by multifrequency electron cyclotron resonance heating at 2.45 and 6.4 GHz, and a population of energetic electrons, with mean energies above 50 keV, dominates the plasma pressure. Creation of high-pressure, high-beta plasma is possible only when intense hot electron interchange instabilities are stabilized by sufficiently 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 time become sufficiently large.

  17. Enhanced efficiency of laser shock cleaning process by geometrical confinement of laser-induced plasma

    SciTech Connect

    Jang, Deoksuk; Oh, Joon Ho; Kim, Dongsik; Lee, Jong-Myoung

    2009-07-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. Accordingly, several studies were performed to expand the cleaning capability of the process. In this work, the cleaning process using laser-induced plasma (LIP) under geometrical confinement is analyzed both theoretically and experimentally. Two-dimensional numerical analysis is conducted to examine the behavior of the LIP shock wave under geometrical confinement for several geometries. As a result of the analysis, we propose a simple and practical method to amplify the intensity of laser-induced shock. In the proposed method, a flat quartz plate placed close to the focal point of the laser pulse confines the expansion of the LIP, allowing the plasma to expand only in one direction. As a consequence of the plasma confinement, the intensity of the shock wave produced is increased significantly. Experiments demonstrate that the enhanced shock wave can remove smaller particles from the surface better than the existing process.

  18. Plasma-Jet Magnetized-Target Fusion Burn Dynamics

    NASA Astrophysics Data System (ADS)

    Santarius, John F.

    2006-10-01

    In magnetized-target fusion (MTF), an imploding, conducting liner compresses a magnetized plasmoid, such as a spheromak or field-reversed configuration (FRC). The increasing magnetic field of the target reduces thermal conduction and the liner's inertia provides transient plasma stability and confinement. This poster explores the burn dynamics of using plasma jets to form the liner [1]. The investigation uses the University of Wisconsin’s 1 D Lagrangian radiation hydrodynamics code, BUCKY, which solves single-fluid equations of motion with pressure contributions from electrons, ions, radiation, and fast charged particles, using either ideal-gas or table-lookup equations of state. BUCKY includes ion-electron interactions, PdV work, and fast-ion energy deposition. For this research, the code has been extended to include the magnetic field evolution as the plasmoid compresses plus the dependence of the thermal conductivity and fusion product energy deposition on the magnetic field.[1] Y.C. F. Thio, et al., ``Magnetized Target Fusion in a Spheroidal Geometry with Standoff Drivers,'' in Current Trends in International Fusion Research, E. Panarella, ed. (National Research Council of Canada, Ottawa, Canada, 1999), p. 113.* Research funded by the DOE Office of Fusion Energy Sciences, grant DE-FG02-04ER54751.

  19. Density distribution of a rotating plasma in Tornado magnetic confinement systems

    SciTech Connect

    Kuznetsov, V.M.; Pakhomov, A.B.; Rusakov, A.I.

    1984-12-01

    The density distribution of a rotating plasma in a Tornado magnetic confinement system is calculated under the assumption that the plasma rotates at constant angular velocity throughout the region bounded by the separatrix. The component of the centrifugal inertial force parallel to the magnetic force lines is shown to pinch the plasma toward the equatorial plane of the system. The density distribution depends on the ratio v/T of the plasma drift velocity and temperature. The experimentally measured density distribution can be used to determine v/T and thus to analyze the rotating plasma. If v is known for the rotating plasma then T can be calculated from v, and vice versa.

  20. Study of plasma confinement in ELMO Bumpy Torus with a heavy-ion beam probe

    SciTech Connect

    Bieniosek, F. M.

    1981-01-01

    Plasma confinement in ELMO Bumpy Torus (EBT) is generally strongly dependent on an ambipolar electric field. Spatially resolved measurements of the resulting electric space potential phi/sub sp/ have been made in a single plasma cross section by the heavy-ion beam probe. This diagnostic injects a 4-60-keV beam of (usually) Cs/sup +/ ions into the plasma. Measurement of the energy of Cs/sup 2 +/ secondary ions leaving the plasma gives a continuous monitor of the local space potential. In addition, the total detected Cs/sup 2 +/ ion current is proportional to the product of the local electron density and the ionization rate, which, in turn, is a function of the electron temperature. This signal, nf(T/sub e/), is sensitive to all three electron distributions found in EBT - those of the cold surface plasma, the warm core plasma, and the hot electron ring.

  1. Fabrication of cryogenic inertial-confinement-fusion targets using target free-fall technique. Report No. 2-82

    SciTech Connect

    Kim, K.; Murphy, M.J.

    1982-04-01

    Techniques for fabricating cryogenic inertial confinement fusion targets (i.e., spherical shells containing a uniform layer of DT ice) are investigated using target free-fall concept. Detection and characterization of the moving targets are effected by optoelectronic means, of which the principal is an RF ac-interferometer. This interferometer system demonstrates, for the first time, the speed capabilities of the phase-modulation ac-interferometry. New techiques developed for handling, holding, launching, and transporting targets are also described. Results obtained at both room and cryogenic temperatures are presented.

  2. Multi-fluid studies of plasma shocks relevant to inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Srinivasan, B.; Kagan, G.; Adams, C. S.

    2016-05-01

    Results from inertial confinement fusion (ICF) experiments performed at the Omega laser facility suggest the potential role of kinetic effects in plasmas during implosion. Recent theoretical and numerical work has indicated the importance of diffusion effects in the presence of multiple ion species as well as the importance of ion viscosity. This provides the motivation to adequately develop multi-fluid plasma models capable of capturing kinetic physics including concentration diffusion and ion species separation driven by the ion concentration gradient, the ion pressure gradient, the electron and ion temperature gradients, and the electric field. Benchmarks between the newly developed code and analytical results are presented for multi-fluid plasma shocks.

  3. Dynamic materials evaluation by confined plasma ablation and laser-generated shocks

    NASA Astrophysics Data System (ADS)

    Paisley, Dennis L.; Swift, D. C.; Forsman, A. C.; Kyrala, George A.; Johnson, Randall P.; Kopp, Roger A.; Hauer, Allan A.; Wark, Justin S.; Loveridge, A.; Allen, A. M.; Kalantar, Daniel H.

    2000-08-01

    Laser-generated shocks can and have been used to study their effects on single crystal materials during shock compression. While a crystal undergoes shock compression and release, the transient x- ray diffraction (TXD) of the Bragg and Laue signals is indicative of the change in the crystal lattice spacing. The lattice spacing directly relates to the strain in the crystal. From the dynamic lattice data, strain, strain rate, and/or phase change in a material may be determined. Confined ablation plasmas can efficiently launch a flyer plate for direct impact on a target material imparting a well-characterized shock input and generate kilobar to megabar pressure pulses over a wide range of pulse duration (= 20 ns). The laser-launched flyer plates are analogous to those launched by gas guns, but the smaller size provides an experimental method not easily accessible by larger gas gun experiments. With lasers, diagnostic equipment can be easily synchronized to study dynamic material parameters, i.e., single crystal shock dynamics, interfacial bond strengths of thin coatings, grain-interfaces, texture, and high strain rates (106 - 109 sec-1).

  4. Tridimensional Burning Structures Associated with Anisotropic Thermal Conductivities in Magnetically Confined and Pulsar Plasmas

    NASA Astrophysics Data System (ADS)

    Cardinali, A.; Coppi, B.; Sonnino, G.

    2015-11-01

    A surprising result of the most recent theory of the thermonuclear instability, which can take place in D-T plasmas close to ignition, is that it can develop with tridimensional structures emerging from an axisymmetric toroidal confinement configurations. These structures are helical filaments (``snakes'') that are localized radially around a given rational magnetic surface. Until now well known analyses of fusion burning processes in magnetically confined plasmas, that include the thermonuclear instability, have been carried out by 1+1/2 D transport codes and, consequently, the onset of tri-dimensional structures has not been investigated. The importance of the electron thermal conductivities anisotropy is pointed out also for the inhomogeneous thermonuclear burning of plasmas on the surface of pulsars and for the formation of the observed bright spots on some of them. Sponsored in part by the U.S. DoE.

  5. Hot-electron plasma formation and confinement in the tandem mirror experiment-upgrade

    SciTech Connect

    Ress, D.B.

    1988-06-01

    The tandem mirror experiment-upgrade (TMX-U) at the Lawrence Livermore National Laboratory (LLNL) is the first experiment to investigate the thermal-barrier tandem-mirror concept. One attractive feature of the tandem magnetic mirror as a commercial power reactor is that the fusion reactions occur in an easily accessible center-cell. On the other hand, complicated end-cells are necessary to provide magnetohydrodynamic (MHD) stability and improved particle confinement of the center-cell plasma. In these end-cells, enhanced confinement is achieved with a particular axial potential profile that is formed with electron-cyclotron range-of-frequency heating (ECRF heating, ECRH). By modifying the loss rates of electrons at spatially distinct locations within the end-cells, the ECRH can tailor the plasma potential profile in the desired fashion. Specifically, the thermal-barrier concept requires generation of a population of energetic electrons near the midplane of each end-cell. To be effective, the transverse (to the magnetic field) spatial structure of the hot-electron plasma must be fairly uniform. In this dissertation we characterize the spatial structure of the ECRH-generated plasma, and determine how the structure builds up in time. Furthermore, the plasma should efficiently absorb the ECRF power, and a large fraction of the electrons must be well confined near the end-cell midplane. Therefore, we also examine in detail the ECRH power balance, determining how the ECRF power is absorbed by the plasma, and the processes through which that power is confined and lost. 43 refs., 69 figs., 6 tabs.

  6. Laboratory studies of kinetic instabilities under double plasma resonance condition in a mirror-confined non-equilibrium plasma

    NASA Astrophysics Data System (ADS)

    Viktorov, Mikhail; Golubev, Sergey; Mansfeld, Dmitry; Vodopyanov, Alexander; Zaitsev, Valery

    2016-04-01

    Plasma instabilities in magnetic traps on the Sun are the sources of powerful broadband radio emission (the so-called type IV bursts) which is interpreted as the excitation of plasma waves by fast electrons in the upper hybrid resonance frequency followed by transformation in electromagnetic waves. In the case of double plasma resonance condition when the frequency of the upper hybrid resonance coincides with one of the electron gyrofrequency harmonics the instability increment of plasma waves is greatly increased. This leads to the appearance of bright narrow-band radio emission near the harmonics of the electron gyrofrequency - the so-called zebra patterns. With the use of non-equilibrium mirror-confined plasma produced by the electron cyclotron resonance (ECR) discharge we provide the possibility to study plasma instabilities under double plasma resonance condition in the laboratory. In the experiment such conditions are fulfilled just after ECR heating switch-off, i.e. in the very beginning of a dense plasma decay phase. The observed instability is accompanied by a pulse-periodic generation of a powerful electromagnetic radiation at a frequency close to the upper hybrid resonance frequency and a second harmonic of the electron gyrofrequency, and synchronous precipitations of fast electrons from the trap ends. It is shown that the observed instability is due to the excitation of plasma waves at a double plasma resonance in decaying plasma of the ECR discharge. Possible manifestations of double plasma resonance effect are not rare in astrophysical plasmas. The phenomenon of zebra pattern is observed not only on the Sun, but in the decametric radiation of the Jupiter, kilometric radiation of the Earth and even in the radio emissions of pulsars. Thus, verification of the effect of double plasma resonance in a laboratory plasma experiments is a very relevant task.

  7. Surface-confined activation of ultra low-k dielectrics in CO2 plasma

    NASA Astrophysics Data System (ADS)

    Sun, Yiting; Krishtab, Mikhail; Mankelevich, Yuri; Zhang, Liping; De Feyter, Steven; Baklanov, Mikhail; Armini, Silvia

    2016-06-01

    An approach allowing surface-confined activation of porous organosilicate based low-k dielectrics is proposed and studied. By examining the plasma damage mechanism of low-k, we came up with an initial idea that the main requirements for the surface-confined modification would be the high reactivity and high recombination rate of the plasma species. Based on this concept, CO2 plasma was selected and benchmarked with several other plasmas. It is demonstrated that a short exposure of organosilicate low-k films to CO2 plasma enables high surface hydrophilicity with limited bulk modification. CO2+ ions predominantly formed in this plasma have high oxidation potential and efficiently remove surface -CH3 groups from low-k. At the same time, the CO2+ ions get easily discharged (deactivated) during their collisions with pore walls and therefore have very limited probability of penetration into the low-k bulk. Low concentration of oxygen radicals is another factor avoiding the bulk damage. The chemical reactions describing the interactions between CO2 plasma and low-k dielectrics are proposed.

  8. Nonlinear competition of turbulent structures and improved confinement in magnetized cylindrical plasmas

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Kasuya, N.; Itoh, K.; Yagi, M.; Itoh, S.-I.

    2014-11-01

    Nonlinear competition of turbulent structures and their roles in transport are investigated by using three-dimensional simulation code of resistive drift wave turbulence in magnetized cylindrical plasmas. Selective formation of zonal flows and streamers has been obtained by controlling the strength of damping of the zonal flow. In addition, there is an energy path from the drift waves to a flute type structure, which is linearly stable, and it becomes effective just below the stability boundary of the zonal flow. The flute structure directly induces transport effectively, and affects the drift waves and the zonal flow. A large amplitude zonal flow is formed selectively even with existence of the flute structure. The property of the particle confinement is investigated by changing the particle source intensity, which controls the strength of driving of the drift waves. The characteristic of the particle confinement changes according to turbulent states, and an improved confinement regime is obtained in the zonal flow dominant state. Study on cylindrical plasmas reveals the fundamental mechanism of improved confinement in the magnetized plasma with influence of turbulent structural formation.

  9. Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

    SciTech Connect

    Hu, S. X. Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militzer, B.

    2015-05-15

    A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κ{sub QMD}), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ∼2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP

  10. Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

    DOE PAGESBeta

    Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militizer, B.

    2015-04-20

    In this study, a comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximatelymore » taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (KQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of –2.5; the lower the adiabat of DT capsules, the more variations in hydro

  11. Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

    SciTech Connect

    Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militizer, B.

    2015-04-20

    In this study, a comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (KQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of –2.5; the lower the adiabat of DT capsules, the more variations in hydro

  12. Impact of first-principles properties of deuterium-tritium on inertial confinement fusion target designsa)

    NASA Astrophysics Data System (ADS)

    Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militzer, B.

    2015-05-01

    A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium-tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF "path" to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ˜2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT

  13. Improved confinement region without large magnetohydrodynamic activity in TPE-RX reversed-field pinch plasma

    SciTech Connect

    Yambe, Kiyoyuki; Hirano, Yoichi; Sakakita, Hajime; Koguchi, Haruhisa

    2014-11-15

    We found that spontaneous improved confinement was brought about depending on the operating region in the Toroidal Pinch Experiment-Reversed eXperiment (TPE-RX) reversed-field pinch plasma [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. Gradual decay of the toroidal magnetic field at plasma surface B{sub tw} reversal makes it possible to realize a prolonged discharge, and the poloidal beta value and energy confinement time increase in the latter half of the discharge, where reversal and pinch parameters become shallow and low, respectively. In the latter half of the discharge, the plasma current and volume-averaged toroidal magnetic field 〈B{sub t}〉 increase again, the electron density slowly decays, the electron temperature and soft X-ray radiation intensity increase, and the magnetic fluctuations are markedly reduced. In this period of improved confinement, the value of (〈B{sub t}〉-B{sub tw})/B{sub pw}, where B{sub pw} is the poloidal magnetic field at the plasma surface, stays almost constant, which indicates that the dynamo action occurs without large magnetohydrodynamic activities.

  14. New steady-state quiescent high-confinement plasma in an experimental advanced superconducting tokamak.

    PubMed

    Hu, J S; Sun, Z; Guo, H Y; Li, J G; Wan, B N; Wang, H Q; Ding, S Y; Xu, G S; Liang, Y F; Mansfield, D K; Maingi, R; Zou, X L; Wang, L; Ren, J; Zuo, G Z; Zhang, L; Duan, Y M; Shi, T H; Hu, L Q

    2015-02-01

    A critical challenge facing the basic long-pulse high-confinement operation scenario (H mode) for ITER is to control a magnetohydrodynamic (MHD) instability, known as the edge localized mode (ELM), which leads to cyclical high peak heat and particle fluxes at the plasma facing components. A breakthrough is made in the Experimental Advanced Superconducting Tokamak in achieving a new steady-state H mode without the presence of ELMs for a duration exceeding hundreds of energy confinement times, by using a novel technique of continuous real-time injection of a lithium (Li) aerosol into the edge plasma. The steady-state ELM-free H mode is accompanied by a strong edge coherent MHD mode (ECM) at a frequency of 35-40 kHz with a poloidal wavelength of 10.2 cm in the ion diamagnetic drift direction, providing continuous heat and particle exhaust, thus preventing the transient heat deposition on plasma facing components and impurity accumulation in the confined plasma. It is truly remarkable that Li injection appears to promote the growth of the ECM, owing to the increase in Li concentration and hence collisionality at the edge, as predicted by GYRO simulations. This new steady-state ELM-free H-mode regime, enabled by real-time Li injection, may open a new avenue for next-step fusion development.

  15. Confinement effects of magnetic field on two-dimensional hydrogen atom in plasmas

    SciTech Connect

    Bahar, M. K.; Soylu, A.

    2015-05-15

    In this study, for the first time, the Schrödinger equation with more general exponential cosine screened Coulomb (MGECSC) potential is solved numerically in the presence and in the absence of an external magnetic field within two-dimensional formalism using the asymptotic iteration method. The MGECSC potential includes four different potential forms when considering different sets of the parameters in the potential. The plasma screening effects in the weak and strong magnetic field regimes as well as the confinement effects of magnetic field on the two-dimensional hydrogen atom in Debye and quantum plasmas are investigated by solving the corresponding equations. It is found that applying a uniform magnetic field on the hydrogen atom embedded in a plasma leads to change in the profile of the total interaction potential. Thus, confinement effects of magnetic field on hydrogen atom embedded in Debye and quantum plasmas modeled by a MGECSC potential lead to shift bound state energies. This effect would be important to isolate the plasma from the external environment in the experimental applications of plasma physics.

  16. Fast Ion Confinement in High Beta, Steady-State Scenario Plasmas

    NASA Astrophysics Data System (ADS)

    Heidbrink, W. W.; Chen, X.; Ferron, J. R.; van Zeeland, M. A.; Grierson, B. A.; Holcomb, C. T.

    2013-10-01

    Fast-ion confinement is studied for qmin between 1.2-2.8 in plasmas with normalized β > 2 . 6 . Fast-ion D-alpha (FIDA), neutron, and neutral-particle diagnostics measure the confined fast ions. Tearing modes and a ``sea'' of unstable Alfvén eigenmodes (AE) are observed. In preliminary analysis, the degradation in fast-ion confinement increases with qmin ; increased AE activity appears responsible. Predictions of a model that assumes that AE-induced fast-ion transport is stiff are compared with the data. Work supported by the US Department of Energy under SC-G903402, DE-FC-02-04ER54698, DE-AC02-09CH11466, and DE-AC52-07NA27344.

  17. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    DOEpatents

    Motley, Robert W.; Glanz, James

    1985-01-01

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  18. Robustness of predator-prey models for confinement regime transitions in fusion plasmas

    SciTech Connect

    Zhu, H.; Chapman, S. C.; Dendy, R. O.

    2013-04-15

    Energy transport and confinement in tokamak fusion plasmas is usually determined by the coupled nonlinear interactions of small-scale drift turbulence and larger scale coherent nonlinear structures, such as zonal flows, together with free energy sources such as temperature gradients. Zero-dimensional models, designed to embody plausible physical narratives for these interactions, can help to identify the origin of enhanced energy confinement and of transitions between confinement regimes. A prime zero-dimensional paradigm is predator-prey or Lotka-Volterra. Here, we extend a successful three-variable (temperature gradient; microturbulence level; one class of coherent structure) model in this genre [M. A. Malkov and P. H. Diamond, Phys. Plasmas 16, 012504 (2009)], by adding a fourth variable representing a second class of coherent structure. This requires a fourth coupled nonlinear ordinary differential equation. We investigate the degree of invariance of the phenomenology generated by the model of Malkov and Diamond, given this additional physics. We study and compare the long-time behaviour of the three-equation and four-equation systems, their evolution towards the final state, and their attractive fixed points and limit cycles. We explore the sensitivity of paths to attractors. It is found that, for example, an attractive fixed point of the three-equation system can become a limit cycle of the four-equation system. Addressing these questions which we together refer to as 'robustness' for convenience is particularly important for models which, as here, generate sharp transitions in the values of system variables which may replicate some key features of confinement transitions. Our results help to establish the robustness of the zero-dimensional model approach to capturing observed confinement phenomenology in tokamak fusion plasmas.

  19. Plasma confinement to enhance the momentum coupling coefficient in ablative laser micro-propulsion: a novel approach

    NASA Astrophysics Data System (ADS)

    Ahmad, Muhammad Raza; Jamil, Yasir; Qaiser Zakaria, M.; Hussain, Tousif; Ahmad, Riaz

    2015-07-01

    We introduce for the first time the novel idea of manipulating the momentum coupling coefficient using plasma confinement and shock wave reflection from the cavity walls. The plasma was confined using cylindrical geometries of various cavity aspect ratios to manipulate the momentum coupling coefficient (C m ). The Nd: YAG laser (532 nm, 5 ns pulse duration) was focused on the ferrite sample surface to produce plasma in a region surrounded by cylindrical cavity walls. The multiple reflections of the shockwaves from the cavity walls confined the laser-induced plasma to the central region of the cavity that subsequently resulted in a significant enhancement of the momentum coupling coefficient values. The plasma shielding effect has also been observed for particular values of laser fluencies and cavity aspect ratios. Compared with the direct ablation, the confined ablation provides an effective way to obtain high C m values.

  20. Banana fluxes in the plateau regime for a nonaxisymmetrically confined plasma

    SciTech Connect

    Balescu, R.; Fantechi, S. )

    1990-09-01

    The banana (or banana-plateau) fluxes, related to the generalized stresses {l angle}{bold B}{center dot}{del}{center dot}{pi}{sup {alpha}({ital n})}{r angle}, {l angle}{bold B}{sub {ital T}}{center dot}{del}{center dot}{pi}{sup {alpha}({ital n})}{r angle} have been determined in the plateau regime, for a plasma confined by a toroidal magnetic field of arbitrary geometry. The complete set of transport coefficients for both the parallel'' (ambipolar) and toroidal'' (nonambipolar) banana fluxes was obtained in the 13-moment (13M) approximation, going beyond the previously known expressions in the nonaxisymmetric case. The main emphasis is laid on the structure of the transport matrix and of its coefficients. It is shown that the Onsager symmetry of this matrix partly breaks down (for the mixed electron--ion coefficients) in a nonaxisymmetrically confined plasma.

  1. Is Onsager symmetry relevant in the transport equations for magnetically confined plasmas

    SciTech Connect

    Balescu, R. )

    1991-03-01

    A global, algebraic view of the transport processes in a magnetically confined plasma is developed. Both the neoclassical (banana) and the anomalous transport matrices are represented in a factorized form, thus separating the roles of the dynamics and of the geometric constraints. The self-adjointness of the collision operator (the sole condition for classical Onsager symmetry) is shown to be a necessary, but not sufficient condition for this symmetry in confined plasmas. The latter results for the banana transport matrix from a delicate relationship between dynamic and geometric components. This structure is not present in the anomalous transport matrix, and the Onsager symmetry is broken in this case. It is stressed that the symmetry breaking does not violate any general principles.

  2. Population inversion and gain measurements for X-ray laser development in magnetically confined plasma column in fiscal year 1984

    NASA Astrophysics Data System (ADS)

    Suckewer, S.

    1985-03-01

    This report covers X-ray laser development in magnetically confined plasmas, as well as in expanding recombining plasma columns using time resolved soft X-ray monochromators. Experiments with both solid and gas targets resulted in gain measurements for hydrogen-like Carbon(6+) (CVI) ions and population inversion measurements for lithium-like Neon(8+) (NeVIII) ions. Our most recent results, involving carbon disc targets in a 90 k Gauss field with a 300 Joule carbon dioxide laser pulse, in which a one-pass gain of kl 6.5 (enhancement of stimulated emission over spontaneous emission about 100) was obtained for CVI 182A are presented. Results of a gain kl = 3.0 (k approx. 7.5/cm) for thick carbon fiber targets are also presented. Population inversions of NeVIII ions as a function of initial gas pressure are also discussed, as well as an overview of the instrumentation, experimental setup, and target configurations used.

  3. A low energy positron accumulator for the plasma confinement in a compact magnetic mirror trap

    SciTech Connect

    Higaki, Hiroyuki Kaga, Chikato; Nagayasu, Katsushi; Okamoto, Hiromi; Nagata, Yugo; Kanai, Yasuyuki; Yamazaki, Yasunori

    2015-06-29

    A low energy positron accumulator was constructed at RIKEN for the purpose of confining an electron-positron plasma. The use of 5 mCi {sup 22}Na RI source with a standard solid Ne moderator and N{sub 2} buffer gas cooling resulted in a low energy positron yield of ∼ 3 × 10{sup 5} e+/s. So far, 2 × 10{sup 6} positrons have been accumulated in 120s.

  4. Observation of a high-confinement regime in a tokamak plasma with ion cyclotron resonance heating

    NASA Astrophysics Data System (ADS)

    Steinmetz, K.; Noterdaeme, J.-M.; Wagner, F.; Wesner, F.; Bäumler, J.; Becker, G.; Bosch, H. S.; Brambilla, M.; Braun, F.; Brocken, H.; Eberhagen, A.; Fritsch, R.; Fussmann, G.; Gehre, O.; Gernhardt, J.; v. Gierke, G.; Glock, E.; Gruber, O.; Haas, G.; Hofmann, J.; Hofmeister, F.; Izvozchikov, A.; Janeschitz, G.; Karger, F.; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; van Mark, E.; Mast, F.; Mayer, H. M.; McCormick, K.; Meisel, D.; Mertens, V.; Müller, E. R.; Murmann, H.; Niedermeyer, H.; Poschenrieder, W.; Puri, S.; Rapp, H.; Röhr, H.; Ryter, F.; Schmitter, K.-H.; Schneider, F.; Setzensack, C.; Siller, G.; Smeulders, P.; Söldner, F.; Speth, E.; Steuer, K.-H.; Vollmer, O.; Wedler, H.; Zasche, D.

    1987-01-01

    The H mode in ion cyclotron-resonance-heated plasmas has been investigated with and without additional neutral beam injection. Ion cyclotron-resonance heating can cause the transition into a high-confinement regime (H mode) in combination with beam heating. The H mode, however, has also been realized-for the first time-with ion cyclotron-resonance heating alone in the D (H)-hydrogen minority scheme at an absorbed rf power of 1.1 MW.

  5. Experimental Observation of a Periodically Oscillating Plasma Sphere in a Gridded Inertial Electrostatic Confinement Device

    SciTech Connect

    Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar

    2005-07-01

    The periodically oscillating plasma sphere (POPS) [D. C. Barnes and R. A. Nebel, Phys. Plasmas 5, 2498 (1998).] oscillation has been observed in a gridded inertial electrostatic confinement device. In these experiments, ions in the virtual cathode exhibit resonant behavior when driven at the POPS frequency. Excellent agreement between the observed POPS resonance frequency and theoretical predictions has been observed for a wide range of potential well depths and for three different ion species. The results provide the first experimental validation of the POPS concept proposed by Barnes and Nebel [R. A. Nebel and D. C. Barnes, Fusion Technol. 34, 28 (1998).].

  6. An empirical scaling law for improved confinement in reversed-field pinch plasmas

    NASA Astrophysics Data System (ADS)

    Yagi, Y.; Koguchi, H.; Hirano, Y.; Sakakita, H.; Frassinetti, L.

    2005-02-01

    A database of the confinement properties of the toroidal pinch experiment (TPE) series reversed-field pinch (RFP) devices was established, and an empirical scaling law for the energy confinement time, τE, was deduced for a consistently selected set of the database (Yagi Y. et al 2003 Nucl. Fusion 43 1787). The scaling for τE [TPE-scaling; \\smash{\\tau _E \\sim a^{1.7} I_p^{0.8} (I_p/N)^{0.3} \\Theta ^{3}} ], in particular, is a power law similar to that predicted on the basis of the tearing modes, as a function of the plasma minor radius (a), plasma current (Ip), and Ip/N, where N is the column density. On the other hand, the TPE-scaling has a strong dependence on the pinch parameter, Θ, namely τE ~ Θ3. Recently, we have investigated the database of the improved confinement in the pulsed poloidal current drive (PPCD). We show that the TPE-scaling agrees well with the improved τE in the PPCD database, because of its strong Θ dependence. Namely, Θ3 is a factor of merit for RFP plasmas. We discuss why this agreement is obtained in spite of the general difference between the underlying transport mechanisms of the standard and PPCD discharges. We also show that this improvement, represented by Θ3, is related to the increase in magnetic shear with Θ.

  7. Investigations into the seeding of instabilities due to x-ray preheat in beryllium-based inertial confinement fusion targets

    SciTech Connect

    Loomis, E. N.; Greenfield, S. R.; Johnson, R. P.; Cobble, J. A.; Luo, S. N.; Montgomery, D. S.; Marinak, M. M.

    2010-05-15

    The geometry of inertial confinement fusion (ICF) capsules makes them susceptible to various types of hydrodynamic instabilities at different stages during an ICF implosion. From the beginnings of ICF research, it has been known that grain-level anisotropy and defects could be a significant source of instability seeding in solid beryllium capsules. We report on experiments conducted at the Trident laser facility [S. H. Batha et al., Rev. Sci. Instrum. 79, 10F305 (2008)] to measure dynamic surface roughening from hard x-ray preheat due to anisotropic thermal expansion. M-band emission from laser-produced gold plasma was used to heat beryllium targets with different amounts of copper doping to temperatures comparable to ICF ignition preheat levels. Dynamic roughening measurements were made on the surface away from the plasma at discrete times up to 8 ns after the beginning of the drive pulse using a surface displacement interferometer with nanometer scale sensitivity. Undoped large-grained targets were measured to roughen between 15 and 50 nm rms. Fine-grained, copper-doped targets were observed to roughen near the sensitivity limit of the interferometer. The results of this work have shed light on the effects of high-Z doping and microstructural refinement on the dynamics of differential thermal expansion and have shown that current ICF capsule designs using beryllium are very effective in reducing preheat related roughening ahead of the first shock.

  8. Searching target sites on DNA by proteins: Role of DNA dynamics under confinement

    PubMed Central

    Mondal, Anupam; Bhattacherjee, Arnab

    2015-01-01

    DNA-binding proteins (DBPs) rapidly search and specifically bind to their target sites on genomic DNA in order to trigger many cellular regulatory processes. It has been suggested that the facilitation of search dynamics is achieved by combining 3D diffusion with one-dimensional sliding and hopping dynamics of interacting proteins. Although, recent studies have advanced the knowledge of molecular determinants that affect one-dimensional search efficiency, the role of DNA molecule is poorly understood. In this study, by using coarse-grained simulations, we propose that dynamics of DNA molecule and its degree of confinement due to cellular crowding concertedly regulate its groove geometry and modulate the inter-communication with DBPs. Under weak confinement, DNA dynamics promotes many short, rotation-decoupled sliding events interspersed by hopping dynamics. While this results in faster 1D diffusion, associated probability of missing targets by jumping over them increases. In contrast, strong confinement favours rotation-coupled sliding to locate targets but lacks structural flexibility to achieve desired specificity. By testing under physiological crowding, our study provides a plausible mechanism on how DNA molecule may help in maintaining an optimal balance between fast hopping and rotation-coupled sliding dynamics, to locate target sites rapidly and form specific complexes precisely. PMID:26400158

  9. Fueling of magnetically confined plasmas by single- and two-stage repeating pneumatic pellet injectors

    SciTech Connect

    Gouge, M.J.; Combs, S.K.; Foust, C.R.; Milora, S.L.

    1990-01-01

    Advanced plasma fueling systems for magnetic fusion confinement experiments are under development at Oak Ridge National Laboratory (ORNL). The general approach is that of producing and accelerating frozen hydrogenic pellets to speeds in the kilometer-per-second range using single shot and repetitive pneumatic (light-gas gun) pellet injectors. The millimeter-to-centimeter size pellets enter the plasma and continuously ablate because of the plasma electron heat flux, depositing fuel atoms along the pellet trajectory. This fueling method allows direct fueling in the interior of the hot plasma and is more efficient than the alternative method of injecting room temperature fuel gas at the wall of the plasma vacuum chamber. Single-stage pneumatic injectors based on the light-gas gun concept have provided hydrogenic fuel pellets in the speed range of 1--2 km/s in single-shot injector designs. Repetition rates up to 5 Hz have been demonstrated in repetitive injector designs. Future fusion reactor-scale devices may need higher pellet velocities because of the larger plasma size and higher plasma temperatures. Repetitive two-stage pneumatic injectors are under development at ORNL to provide long-pulse plasma fueling in the 3--5 km/s speed range. Recently, a repeating, two-stage light-gas gun achieved repetitive operation at 1 Hz with speeds in the range of 2--3 km/s.

  10. Measurement of RF electric field in high- β plasma using a Pockels detector in magnetosphere plasma confinement device RT-1

    NASA Astrophysics Data System (ADS)

    Mushiake, Toshiki; Nishiura, M.; Yoshida, Z.; Yano, Y.; Kawazura, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, Atsushi

    2015-11-01

    The magnetosphere plasma confinement device RT-1 generates a dipole magnetic field that can confine high- β plasma by using a levitated superconducting coil. So far it is reported that high temperature electrons (up to 50keV) exist and that the local electron βe value exceeds more than 100%. However, the ion β value βi remains low in the present high- β state. To realize a high-βi state, we have started Ion Cyclotron Heating (ICH) experiments. For efficient ICH in a dipole topology, it is important to measure RF electric fields and characterize the propagation of RF waves in plasmas. On this viewpoint, we started direct measurement of local RF electric fields in RT-1 with a Pockels sensor system. A non-linear optical crystal in the Pockels sensor produces birefringence in an ambient electric field. The refractive index change of the birefringence is proportional to the applied electric field strength, which can be used to measure local electric fields. RF electric field distribution radiated from an ICH antenna was measured inside RT-1 in air, and was compared with numerical results calculated by TASK code. Results on the measurement of electric field distribution in high- β plasma and evaluation of the absorbed RF power into ions will be reported. Supported by JSPS KAKENHI Grant Numbers 23224014.

  11. Knudsen and inverse Knudsen layer effect on tail ion distribution and fusion reactivity in inertial confinement fusion targets

    NASA Astrophysics Data System (ADS)

    McDevitt, C. J.; Tang, X.-Z.; Guo, Z.; Berk, H. L.

    2014-10-01

    A series of reduced models are used to study the fast ion tail in the vicinity of a transition layer between plasmas at disparate temperatures and densities, which is typical of the gas-pusher interface in inertial confinement fusion targets. Emphasis is placed on utilizing progressively more comprehensive models in order to identify the essential physics for computing the fast ion tail at energies comparable to the Gamow peak. The resulting fast ion tail distribution is subsequently used to compute the fusion reactivity as a function of collisionality and temperature. It is found that while the fast ion distribution can be significantly depleted in the hot spot, leading to a reduction of the fusion reactivity in this region, a surplus of fast ions is present in the neighboring cold region. The presence of this fast ion surplus in the neighboring cold region is shown to lead to a partial recovery of the fusion yield lost in the hot spot.

  12. Turbulence in Toroidally Confined Plasma: Ion - - Gradient-Driven Turbulence; Dynamics of Magnetic Relaxation in Current-Carrying Plasma

    NASA Astrophysics Data System (ADS)

    Lee, Gyung Su.

    This thesis is devoted to two studies of low-frequency turbulence in toroidally confined plasma. Low-frequency turbulence is believed to play an important role in anomalous transport in toroidal confinement devices. The first study pertains the the development of an analytic theory of ion-temperature-gradient-driven turbulence in tokamaks. Energy-conserving, renormalized spectrum equations are derived and solved in order to obtain the spectra of stationary ion-temperature-gradient-driven turbulence. Corrections to mixing-length estimates are calculated explicitly. The resulting anomalous ion thermal diffusivity is derived and is found to be consistent with experimentally-deduced ion thermal diffusivities. The associated electron thermal diffusivity, particle and heat-pinch velocities are also calculated. The effects of impurity gradients on saturated ion-temperature-gradient-driven turbulence are discussed and a related explanation of density profile steepening during Z-mode operation is proposed. The second study is devoted to the role of multiple helicity nonlinear interactions of tearing modes and dynamics of magnetic relaxation in a high-temperature current-carrying plasma. To extend the resistive MHD theory of magnetic fluctuations and dynamo activity observed in the reversed field pinch, the fluid equations for high-temperature regime are derived and basic nonlinear interaction mechanism and the effects of diamagnetic corrections to the MHD turbulence theory are studied for the case of fully developed, densely packed turbulence. Modifications to the MHD dynamo theory and anomalous thermal transport and confinement scaling predictions are examined.

  13. Spectroscopic diagnostics of plume rebound and shockwave dynamics of confined aluminum laser plasma plumes

    SciTech Connect

    Yeates, P.; Kennedy, E. T.

    2011-06-15

    Generation and expansion dynamics of aluminum laser plasma plumes generated between parallel plates of varying separation ({Delta}Z = 2.0, 3.2, 4.0, and 5.6 mm), which confined plume expansion normal to the ablation surface, were diagnosed. Space and time resolved visible emission spectroscopy in the spectral range {lambda} = 355-470 nm and time gated visible imaging were employed to record emission spectra and plume dynamics. Space and time resolved profiles of N{sub e} (the electron density), T{sub e} (the electron temperature), and T{sub ionz} (the ionization temperature) were compared for different positions in the plasma plume. Significant modifications of the profiles of the above parameters were observed for plasma-surface collisions at the inner surface of the front plate, which formed a barrier to the free expansion of the plasma plume generated by the laser light on the surface of the back plate. Shockwave generation at the collision interface resulted in delayed compression of the low-density plasma plume near the inner ablation surface, at late stages in the plasma history. Upon exiting the cavity formed by the two plates, through an aperture in the front plate, the plasma plume underwent a second phase of free expansion.

  14. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    SciTech Connect

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-10-15

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al{sub 2}O{sub 3} layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al{sub 2}O{sub 3} films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  15. Plasma confinement by magnetic field with convex-concave field lines

    NASA Astrophysics Data System (ADS)

    Tsventoukh, Mikhail M.; Krashevskaya, Galina V.; Prishvitsyn, Alexander S.

    2015-06-01

    It has been found that plasma confinement by the magnetic field of alternating-sign curvature with convex-concave field lines results in a strong stabilizing action against convective (flute-interchange) perturbations. For simple combinations of axisymmetric mirrors and cusps the calculations according to the kinetic stability criterion give strongly, centrally peaked stable plasma pressure profiles instead of shallow ones. For the experimental research of this effect, a compact magnetic confinement device has been modified by adding of the external current coil to fulfil the field-line curvature requirements. The critical convectively-stable plasma pressure profiles calculation in this experimental geometry and the probe measurements of the spatial plasma distribution in the new magnetic configuration of alternating-sign curvature have been performed. The experimental results give some support for a conclusion that there is an increase in the ion saturation current at the region near the minimum of the specific volume min ∫dl/B. This region corresponds to the average minimum in the second adiabatic invariant, and the kinetic description predicts the stable pressure profile peaking here due to reduction of charge separation by particle drift in alternating-sign curvature.

  16. Intense field induced excitation and ionization of an atom confined in a dense quantum plasma

    NASA Astrophysics Data System (ADS)

    Lumb, Shalini; Lumb, Sonia; Munjal, D.; Prasad, V.

    2015-09-01

    Exponential cosine screened Coulomb potential (ECSCP) has been widely used in various branches of physics e.g., solid-state physics, nuclear physics and plasma physics. The atomic photoionization processes under plasma shielding can serve as an efficient tool for study of plasma properties in various environments ranging from nano-scale devices to astrophysical objects. In the present study, ECSCP has been used to characterize a dense quantum plasma and its effect on the spectrum of an atom encaged in a spherical box has been investigated. The work has further been extended to study the response of such a system to a periodic laser field. Photoexcitation and ionization probabilities of the system have been studied as a function of applied laser field parameters using the non-perturbative Floquet technique. As the Floquet method requires exact energy values and oscillator strengths, the spectrum of confined system has been calculated using Bernstein-polynomial method. The variation of energy spectrum and oscillator strengths with screening as well as confinement parameters has also been explored.

  17. Generation and compression of a target plasma for magnetized target fusion

    SciTech Connect

    Kirkpatrick, R.C.; Lindemuth, I.R.; Sheehey, P.T.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Magnetized target fusion (MTF) is intermediate between the two very different approaches to fusion: inertial and magnetic confinement fusion (ICF and MCF). Results from collaboration with a Russian MTF team on their MAGO experiments suggest they have a target plasma suitable for compression to provide an MTF proof of principle. This LDRD project had tow main objectives: first, to provide a computational basis for experimental investigation of an alternative MTF plasma, and second to explore the physics and computational needs for a continuing program. Secondary objectives included analytic and computational support for MTF experiments. The first objective was fulfilled. The second main objective has several facets to be described in the body of this report. Finally, the authors have developed tools for analyzing data collected on the MAGO a nd LDRD experiments, and have tested them on limited MAGO data.

  18. Static and dynamic properties of confined, cold ion plasmas: MD (molecular dynamics) simulations

    SciTech Connect

    Schiffer, J.P.

    1989-01-01

    Some four years ago it was suggested that in the new generation of heavy ion accelerator storage rings for multiply charged ions, being planned in Europe, one may well attain internal temperatures that would correspond to very cold plasmas. Since that time, the techniques of electron or laser cooling of such beams has evolved and it may well be possible to reach temperatures corresponding to a plasma coupling parameter {Gamma} >> 100. I was fortunate to have had an opportunity to collaborate during 1986-87 with my former colleague Aneesur Rahman, of Molecular Dynamics fame, and we adapted the MD method to the calculation of the properties of cold confined plasmas. After Rahman's premature death two years ago I have continued the exploration of these systems and would like to summarize the results here. 9 refs., 10 figs.

  19. Autowaves in a dc complex plasma confined behind a de Laval nozzle

    NASA Astrophysics Data System (ADS)

    Fink, M. A.; Zhdanov, S. K.; Schwabe, M.; Thoma, M. H.; Höfner, H.; Thomas, H. M.; Morfill, G. E.

    2013-05-01

    Experiments to explore stability conditions and topology of a dense microparticle cloud supported against gravity by a gas flow were carried out. By using a nozzle-shaped glass insert within the glass tube of a dc discharge plasma chamber a weakly ionized gas flow through a de Laval nozzle was produced. The experiments were performed using neon gas at a pressure of 100 Pa and melamine-formaldehyde particles with a diameter of 3.43 μm. The capturing and stable global confining of the particles behind the nozzle in the plasma were demonstrated. The particles inside the cloud behaved as a single convection cell inhomogeneously structured along the nozzle axis in a tube-like manner. The pulsed acceleration localized in the very head of the cloud mediated by collective plasma-particle interactions and the resulting wave pattern were studied in detail.

  20. Spherical plasma oscillations in a reversed-polarity inertial-electrostatic confinement device

    SciTech Connect

    Tuft, C.; Khachan, J.

    2010-11-15

    A pulsed reversed-polarity inertial-electrostatic confinement device has been investigated experimentally using voltage and spectroscopic diagnostics. Large-amplitude oscillations were observed in the floating potential of the plasma immediately following the initiation of the discharge. It is postulated that the observations were the result of coherent ion oscillations within a harmonic potential well formed by a uniform electron density in the center of the device. A simple model of the system predicts the depth of this transient potential well to be approximately 100 V. Observations of the relative occupation of the third and fourth energy levels of hydrogen in the plasma indicated the formation of a Maxwellian electron energy distribution after 20 {mu}s. The results suggest a promising avenue toward a net fusion power gain by utilizing these oscillations to periodically compress and heat the plasma to thermonuclear densities and energies.

  1. Low beta equilibrium and stability for anisotropic pressure closed field line plasma confinement systems

    SciTech Connect

    Pastukhov, V.P.; Ilgisonis, V.I.; Subbotin, A.A.

    1994-05-01

    General formalism is developed to analyze the equilibrium and stability of low beta anisotropic pressure plasmas confined in closed field line magnetic systems. The formalism allows one to consider rather general magnetic systems with nonuniform axis curvature and longitudinal profiles of toroidal and multipole poloidal field. It also allows having a strong pressure anisotropy corresponding to enhanced plasma pressure in mirror cells of the system. As an example of such a system the authors consider the recently proposed linked mirror neutron source (LMNS). Application of the above formalism to the LMNS analysis confirms most of the preliminary results, however, they obtain a considerable reduction of mirror cell axis curvature and an appreciable ellipticity of plasma cross-section in the mirror cell midplane. They have also optimized the longitudinal pressure and magnetic field distribution.

  2. Dynamic Confinement of ITER Plasma by O-Mode Driver at Electron Cyclotron Frequency Range

    NASA Astrophysics Data System (ADS)

    Stefan, V. Alexander

    2009-05-01

    A low B-field side launched electron cyclotron O-Mode driver leads to the dynamic rf confinement, in addition to rf turbulent heating, of ITER plasma. The scaling law for the local energy confinement time τE is evaluated (τE ˜ 3neTe/2Q, where (3/2) neTe is the local plasma thermal energy density and Q is the local rf turbulent heating rate). The dynamics of unstable dissipative trapped particle modes (DTPM) strongly coupled to Trivelpiece-Gould (T-G) modes is studied for gyrotron frequency 170GHz; power˜24 MW CW; and on-axis B-field ˜ 10T. In the case of dynamic stabilization of DTPM turbulence and for the heavily damped T-G modes, the energy confinement time scales as τE˜(I0)-2, whereby I0(W/m^2) is the O-Mode driver irradiance. R. Prater et. al., Nucl. Fusion 48, No 3 (March 2008). E. P. Velikhov, History of the Russian Tokamak and the Tokamak Thermonuclear Fusion Research Worldwide That Led to ITER (Documentary movie; Stefan Studios Int'l, La Jolla, CA, 2008; E. P. Velikhov, V. Stefan.) M N Rosenbluth, Phys. Scr. T2A 104-109 1982 B. B. Kadomtsev and O. P. Pogutse, Nucl. Fusion 11, 67 (1971).

  3. Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma

    NASA Astrophysics Data System (ADS)

    Clayton, D. J.; Chapman, B. E.; O'Connell, R.; Almagri, A. F.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Kaufman, M. C.; Bonomo, F.; Franz, P.; Gobbin, M.; Piovesan, P.

    2010-01-01

    Runaway electrons with energies >100 keV are observed with the appearance of an m =1 magnetic island in the core of otherwise stochastic Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field-pinch plasmas. The island is associated with the innermost resonant tearing mode, which is usually the largest in the m =1 spectrum. The island appears over a range of mode spectra, from those with a weakly dominant mode to those, referred to as quasi single helicity, with a strongly dominant mode. In a stochastic field, the rate of electron loss increases with electron parallel velocity. Hence, high-energy electrons imply a region of reduced stochasticity. The global energy confinement time is about the same as in plasmas without high-energy electrons or an island in the core. Hence, the region of reduced stochasticity must be localized. Within a numerical reconstruction of the magnetic field topology, high-energy electrons are substantially better confined inside the island, relative to the external region. Therefore, it is deduced that the island provides a region of reduced stochasticity and that the high-energy electrons are generated and well confined within this region.

  4. SCR-1: Design and Construction of a Small Modular Stellarator for Magnetic Confinement of Plasma

    NASA Astrophysics Data System (ADS)

    Barillas, L.; Vargas, V. I.; Alpizar, A.; Asenjo, J.; Carranza, J. M.; Cerdas, F.; Gutiérrez, R.; Monge, J. I.; Mora, J.; Morera, J.; Peraza, H.; Queral, V.; Rojas, C.; Rozen, D.; Saenz, F.; Sánchez, G.; Sandoval, M.; Trimiño, H.; Umaña, J.; Villegas, L. F.

    2014-05-01

    This paper describes briefly the design and construction of a small modular stellarator for magnetic confinement of plasma, called Stellarator of Costa Rica 1, or SCR-1; developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica, PlasmaTEC. The SCR-1 is based on the small Spanish stellarator UST_1, created by the engineer Vicente Queral. The SCR-1 will employ stainless steel torus-shaped vacuum vessel with a major radius of 460.33 mm and a cross section radius of 110.25mm. A typical SCR-1 plasma will have an average radius 42.2 mm and a volume of 8 liters (0.01 m3), and an aspect ratio of 5.7. The magnetic resonant field will be 0.0878 T, and a period of 2 (m=2) with a rotational transform of 0.3. The magnetic field will be provided by 12 modular coils, with 8 turns each, with an electrical current of 8704 A per coil (1088 A per turn of each coil). This current will be fed by a bank of cell batteries. The plasma will be heated by ECRH with magnetrons of a total power of 5kW, in the first harmonic at 2.45GHz. The expected electron temperature and density are 15 eV and 1017 m-3 respectively with an estimated confinement time of 7.30 x 10-4 ms. The initial diagnostics on the SCR-1 will consist of a Langmuir probe, a heterodyne microwave interferometer, and a field mapping system. The first plasma of the SCR-1 is expected at the end of 2011.

  5. Spectroscopic modeling and characterization of a collisionally confined laser-ablated plasma plume.

    PubMed

    Sherrill, M E; Mancini, R C; Bailey, J; Filuk, A; Clark, B; Lake, P; Abdallah, J

    2007-11-01

    Plasma plumes produced by laser ablation are an established method for manufacturing the high quality stoichiometrically complex thin films used for a variety of optical, photoelectric, and superconducting applications. The state and reproducibility of the plasma close to the surface of the irradiated target plays a critical role in producing high quality thin films. Unfortunately, this dense plasma has historically eluded quantifiable characterization. The difficulty in modeling the plume formation arises in the accounting for the small amount of energy deposited into the target when physical properties of these exotic target materials are not known. In this work we obtain the high density state of the plasma plume through the use of an experimental spectroscopic technique and a custom spectroscopic model. In addition to obtaining detailed temperature and density profiles, issues regarding line broadening and opacity for spectroscopic characterization will be addressed for this unique environment.

  6. A technique for thick polymer coating of inertial-confinement-fusion targets

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Feng, I.-A.; Wang, T. G.; Kim, H.-G.

    1983-01-01

    A technique to coat a stalk-mounted inertial-confinement fusion (ICF) target with a thick polymer layer has been successfully demonstrated. The polymer solution is first atomized, allowed to coalesce into a droplet, and positioned in a stable acoustic levitating field. The stalk-mounted ICF target is then moved into the acoustic field by manipulating a 3-D positioner to penetrate the surface membrane of the droplet, thus immersing the target in the levitated coating solution. The target inside the droplet is maintained at the center of the levitated liquid using the 3-D positional information provided by two orthogonally placed TV cameras until the drying process is completed. The basic components of the experimental apparatus, including an acoustic levitator, liquid sample deployment device, image acquisition instrumentation, and 3-D positioner, are briefly described.

  7. Method for determining fast-alpha-particle confinement in tokamak plasmas using resonant nuclear reactors

    SciTech Connect

    Cecil, F.E.; Zweben, S.J.; Medley, S.S.

    1986-03-01

    The resonant nuclear reactions D(..cap alpha..,..gamma..)/sup 6/Li, /sup 6/Li(..cap alpha..,..gamma..)/sup 10/B, and /sup 7/Li(..cap alpha..,..gamma..)/sup 11/B are examined as diagnostics of fast-alpha-particle confinement in tokamak plasmas. Gamma rays from these resonant reactions with energies from 2.1 MeV to 9.2 MeV may be used to infer the alpha-particle population between energies of 0.4 MeV and 2.6 MeV. The ratio of these alpha-burnup reactions to the reactions T(D,..gamma..)/sup 5/He and /sup 3/He(D,..gamma..)/sup 5/Li provides a technique for the measurement of alpha confinement.

  8. Cholesterol Modulates CFTR Confinement in the Plasma Membrane of Primary Epithelial Cells

    PubMed Central

    Abu-Arish, Asmahan; Pandzic, Elvis; Goepp, Julie; Matthes, Elizabeth; Hanrahan, John W.; Wiseman, Paul W.

    2015-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) is a plasma-membrane anion channel that, when mutated, causes the disease cystic fibrosis. Although CFTR has been detected in a detergent-resistant membrane fraction prepared from airway epithelial cells, suggesting that it may partition into cholesterol-rich membrane microdomains (lipid rafts), its compartmentalization has not been demonstrated in intact cells and the influence of microdomains on CFTR lateral mobility is unknown. We used live-cell imaging, spatial image correlation spectroscopy, and k-space image correlation spectroscopy to examine the aggregation state of CFTR and its dynamics both within and outside microdomains in the plasma membrane of primary human bronchial epithelial cells. These studies were also performed during treatments that augment or deplete membrane cholesterol. We found two populations of CFTR molecules that were distinguishable based on their dynamics at the cell surface. One population showed confinement and had slow dynamics that were highly cholesterol dependent. The other, more abundant population was less confined and diffused more rapidly. Treatments that deplete the membrane of cholesterol caused the confined fraction and average number of CFTR molecules per cluster to decrease. Elevating cholesterol had the opposite effect, increasing channel aggregation and the fraction of channels displaying confinement, consistent with CFTR recruitment into cholesterol-rich microdomains with dimensions below the optical resolution limit. Viral infection caused the nanoscale microdomains to fuse into large platforms and reduced CFTR mobility. To our knowledge, these results provide the first biophysical evidence for multiple CFTR populations and have implications for regulation of their surface expression and channel function. PMID:26153705

  9. Excitation of the centrifugally driven interchange instability in a plasma confined by a magnetic dipole

    SciTech Connect

    Levitt, B.; Maslovsky, D.; Mauel, M.E.; Waksman, J.

    2005-05-15

    The centrifugally driven electrostatic interchange instability is excited for the first time in a laboratory magnetoplasma. The plasma is confined by a dipole magnetic field, and the instability is excited when an equatorial mesh is biased to induce a radial current that creates rapid axisymmetric plasma rotation. The observed instabilities appear quasicoherent in the lab frame of reference; they have global radial mode structures and low azimuthal mode numbers, and they are modified by the presence of energetic, magnetically confined electrons. The mode structure is measured using a multiprobe correlation technique as well as a novel 96-point polar imaging diagnostic which measures particle flux along field lines that map to the pole. Interchange instabilities caused by hot electron pressure are simultaneously observed at the hot electron drift frequency. Adjusting the hot electron fraction {alpha} modifies the stability as well as the structures of the centrifugally driven modes. In the presence of larger fractions of energetic electrons, m=1 is observed to be the dominant mode. For faster rotating plasmas containing fewer energetic electrons, m=2 dominates. Results from a self-consistent nonlinear simulation reproduce the measured mode structures in both regimes. The low azimuthal mode numbers seen in the experiment and simulation can also be interpreted with a local, linear dispersion relation of the electrostatic interchange instability. Drift resonant hot electrons give the instability a real frequency, inducing stabilizing ion polarization currents that preferentially suppress high-m modes.

  10. Application of Smoothed Particle MHD (SPMHD) techniques to the simulation of magnetically confined plasma dynamics

    NASA Astrophysics Data System (ADS)

    Vela-Vela, Luis; Sanchez, Raul; Reynolds-Barredo, J. Miguel

    2015-11-01

    Magnetically confined plasmas relevant for fusion scenarios are, to first approximation, well described by ideal and resistive MHD. This includes the description of their equilibrium and stability properties, as well as their medium-to-long term nonlinear evolution under external forcing. In many of these cases, one needs to deal with magnetic topologies that include magnetic islands, stochastic regions or that require the consideration of free-moving boundaries. The present work is part of an on-going effort to develop of a numerical code capable of dealing with these situations by taking advantage of the SPMHD formalism that, although widely used in astrophysical plasmas, is not widespread within the fusion community. SPMHD is a particle (i.e., Lagrangian) method particularly well-suited to deal with complicated boundaries while retaining great parallelization benefits. Here, we will report on the adaptation of the SPMHD equations to the case of magnetically confined plasmas, several benchmarking tests typical for MHD codes, and some preliminary results obtained for more elaborate scenarios. Our results suggest that our new code (EVA) can be very advantageous to deal with problems of current interest for the fusion community, including tokamaks and stellarators.

  11. Particle confinement of pellet-fuelled H-mode plasmas in the Mega Ampere Spherical Tokamak

    NASA Astrophysics Data System (ADS)

    Valovič, M.; Axon, K.; Garzotti, L.; Saarelma, S.; Thyagaraja, A.; Akers, R.; Gurl, C.; Kirk, A.; Lloyd, B.; Maddison, G. P.; Patel, A.; Shibaev, S.; Scannell, R.; Taylor, D.; Walsh, M.; MAST Team

    2008-07-01

    This paper quantifies the particle confinement of pellet-fuelled plasmas in the Mega Ampere Spherical Tokamak (MAST). The dataset is restricted mostly to neutral beam heated plasmas and to shallow pellets launched from the high field side. It is shown that the pellet deposition can be explained only by invoking the ∇B drift of the pellet ablatant. The pellet creates a zone with positive density gradient and increased temperature gradient. Simulations show that these changes could increase the level of micro-turbulence and thus enhance further the penetration of pellet-deposited particles towards the core. Post-pellet dynamics of the density profile is characterised by the pellet retention time τpel. It is shown that τpel correlates with the status of the edge transport barrier (L-mode or H-mode) and decreases rapidly for pellet deposition radius rpel approaching the plasma edge. For ELMy H-mode and ITER-like pellets, rpel ≈ 0.8a, the pellet retention time is about 20% of the energy confinement time. The fuelling requirement by the pellets for ITER is discussed.

  12. Resonant magnetic perturbations of edge-plasmas in toroidal confinement devices

    NASA Astrophysics Data System (ADS)

    Evans, T. E.

    2015-12-01

    Controlling the boundary layer in fusion-grade, high-performance, plasma discharges is essential for the successful development of toroidal magnetic confinement power generating systems. A promising approach for controlling the boundary plasma is based on the use of small, externally applied, edge resonant magnetic perturbation (RMP) fields (δ b\\bot\\text{ext}≈ {{10}-4}\\to {{10}-3}~\\text{T} ). A long-term focus area in tokamak fusion research has been to find methods, involving the use of non-axisymmetric magnetic perturbations to reduce the intense particle and heat fluxes to the wall. Experimental RMP research has progressed from the early pioneering work on tokamaks with material limiters in the 1970s, to present day research in separatrix-limited tokamaks operated in high-confinement mode, which is primarily aimed at the mitigation of the intermittent fluxes due edge localized modes (ELMs). At the same time, theoretical research has evolved from analytical models to numerical simulations, including the full 3D complexities of the problem. Following the first demonstration of ELM suppression in the DIII-D tokamak during 2003, there has been a rapid worldwide growth in theoretical, numerical and experimental edge RMP research resulting in the addition of ELM control coils to the ITER baseline design (Loarte et al 2014 Nucl. Fusion 54 033007). This review provides an overview of edge RMP research including a summary of the early theoretical and numerical background along with recent experimental results on improved particle and energy confinement in tokamaks triggered by edge RMP fields. The topics covered make up the basic elements needed for developing a better understanding of 3D magnetic perturbation physics, which is required in order to utilize the full potential of edge RMP fields in fusion relevant high performance, H-mode, plasmas.

  13. Magnetic field generation in Rayleigh-Taylor unstable inertial confinement fusion plasmas.

    PubMed

    Srinivasan, Bhuvana; Dimonte, Guy; Tang, Xian-Zhu

    2012-04-20

    Rayleigh-Taylor instabilities (RTI) in inertial confinement fusion implosions are expected to generate magnetic fields. A Hall-MHD model is used to study the field generation by 2D single-mode and multimode RTI in a stratified two-fluid plasma. Self-generated magnetic fields are predicted and these fields grow as the RTI progresses via the ∇n(e)×∇T(e) term in the generalized Ohm's law. Scaling studies are performed to determine the growth of the self-generated magnetic field as a function of density, acceleration, Atwood number, and perturbation wavelength.

  14. Basic physics of Alfven instabilities driven by energetic particles in toroidally confined plasmas

    SciTech Connect

    Heidbrink, W. W.

    2008-05-15

    Superthermal energetic particles (EP) often drive shear Alfven waves unstable in magnetically confined plasmas. These instabilities constitute a fascinating nonlinear system where fluid and kinetic nonlinearities can appear on an equal footing. In addition to basic science, Alfven instabilities are of practical importance, as the expulsion of energetic particles can damage the walls of a confinement device. Because of rapid dispersion, shear Alfven waves that are part of the continuous spectrum are rarely destabilized. However, because the index of refraction is periodic in toroidally confined plasmas, gaps appear in the continuous spectrum. At spatial locations where the radial group velocity vanishes, weakly damped discrete modes appear in these gaps. These eigenmodes are of two types. One type is associated with frequency crossings of counterpropagating waves; the toroidal Alfven eigenmode is a prominent example. The second type is associated with an extremum of the continuous spectrum; the reversed shear Alfven eigenmode is an example of this type. In addition to these normal modes of the background plasma, when the energetic particle pressure is very large, energetic particle modes that adopt the frequency of the energetic particle population occur. Alfven instabilities of all three types occur in every toroidal magnetic confinement device with an intense energetic particle population. The energetic particles are most conveniently described by their constants of motion. Resonances occur between the orbital frequencies of the energetic particles and the wave phase velocity. If the wave resonance with the energetic particle population occurs where the gradient with respect to a constant of motion is inverted, the particles transfer energy to the wave, promoting instability. In a tokamak, the spatial gradient drive associated with inversion of the toroidal canonical angular momentum P{sub {zeta}} is most important. Once a mode is driven unstable, a wide variety

  15. Apparatus and method for removing particle species from fusion-plasma-confinement devices

    DOEpatents

    Hamilton, G.W.

    1981-10-26

    In a mirror fusion plasma confinement apparatus, method and apparatus are provided for selectively removing (pumping) trapped low energy (thermal) particle species from the end cell region, without removing the still useful high energy particle species, and without requiring large power input to accomplish the pumping. Perturbation magnets are placed in the thermal barrier region of the end cell region at the turning point characteristic of trapped thermal particles, thus deflecting the thermal particles from their closed trajectory, causing them to drift sufficiently to exit the thermal barrier.

  16. Flute instability in a plasma confined by perfectly reflecting end walls

    SciTech Connect

    Farina, D.; Pozzoli, R.; Ryutov, D. )

    1993-11-01

    The magnetohydrodynamic stability of a low-pressure plasma confined along the magnetic field by the end walls that are perfectly reflecting the impinging particles is considered. It is shown that, if the magnetic field lines do not intersect the walls along the normal, a fast instability can develop. An explicit expression for the growth rate has been derived, and an analogy with the usual flute instability has been traced. The instability can play some role in the scrape-off layers of tokamaks with poloidal limiter.

  17. Study of plasma convection and wall interactions in magnetic confinement systems

    NASA Astrophysics Data System (ADS)

    York, T. M.

    1986-06-01

    The subject contract research effort was initiated in September 1976 with two specific tasks: (1) to study the fundamental physics of confinement of an alternate concept (i.e., theta pinch based) devices; and (2) to study and to develop new diagnostic systems for use on major experiments at other locations in the country. There has been active collaboration with Los Alamos National Laboratory and Lawrence Livermore National Laboratory; there has been proposed collaboration with Princeton Plasma Physics Laboratory, Fusion Research Center at the University of Texas, and General Atomics.

  18. The technology and science of steady-state operation in magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Bécoulet, A.; Hoang, G. T.

    2008-12-01

    The steady-state operation of magnetically confined fusion plasmas is considered as one of the 'grand challenges' of future decades, if not the ultimate goal of the research and development activities towards a new source of energy. Reaching such a goal requires the high-level integration of both science and technology aspects of magnetic fusion into self-consistent plasma regimes in fusion-grade devices. On the physics side, the first constraint addresses the magnetic confinement itself which must be made persistent. This means to either rely on intrinsically steady-state configurations, like the stellarator one, or turn the inductively driven tokamak configuration into a fully non-inductive one, through a mix of additional current sources. The low efficiency of the external current drive methods and the necessity to minimize the re-circulating power claim for a current mix strongly weighted by the internal 'pressure driven' bootstrap current, itself strongly sensitive to the heat and particle transport properties of the plasma. A virtuous circle may form as the heat and particle transport properties are themselves sensitive to the current profile conditions. Note that several other factors, e.g. plasma rotation profile, magneto-hydro-dynamics activity, also influence the equilibrium state. In the present tokamak devices, several examples of such 'advanced tokamak' physics research demonstrate the feasibility of steady-state regimes, though with a number of open questions still under investigation. The modelling activity also progresses quite fast in this domain and supports understanding and extrapolation. This high level of physics sophistication of the plasma scenario however needs to be combined with steady-state technological constraints. The technology constraints for steady-state operation are basically twofold: the specific technologies required to reach the steady-state plasma conditions and the generic technologies linked to the long pulse operation of a

  19. Emissive Probe Measurements in a Dual-Frequency-Confined Capacitively-Coupled-Plasma System

    NASA Astrophysics Data System (ADS)

    Linnane, Shane; Ellingboe, Albert R.

    2002-10-01

    Dual frequency confined capacitively coupled plasmas (DFC-CCP) are increasingly used in semiconductor manufacturing for dielectric etching, allowing greater (and independent) control of ion energies and ion flux on the etched substrate. The powered electrode is driven with the summation of 27MHz and 2MHz sinusoidal voltages, while the other electrode is grounded. The electrode areas are similar in size, giving an electrode aspect ratio less than 2. Because of this low aspect ratio, there are large oscillations in the plasma potential. The expectation is for sinusoidal oscillations at the higher driving frequency, due to capacitive sheaths, while a rectified oscillation is expected at the lower driving frequency.(E. Kawamura, V. Vahedi, M. A. Lieberman and C. K. Birdsall, Plasma Sources Sci. Technology. 8 (1999) R45-R64 Work Supported by EURATOM.) Measurements of rf oscillation in the plasma potential taken with a floating emissive probe will be presented. The emissive probe and circuitry allows direct realtime measurement of plasma potential oscillation at both driving frequencies and the harmonics of each, thus allowing measurement of the actual potential on the driven electrode and ion energy incident on grounded electrode.

  20. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    SciTech Connect

    Vold, E. L.; Molvig, K.; Joglekar, A. S.; Ortega, M. I.; Moll, R.; Fenn, D.

    2015-11-15

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.

  1. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    NASA Astrophysics Data System (ADS)

    Vold, E. L.; Joglekar, A. S.; Ortega, M. I.; Moll, R.; Fenn, D.; Molvig, K.

    2015-11-01

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.

  2. Stable anisotropic plasma confinement in magnetic configurations with convex-concave field lines

    NASA Astrophysics Data System (ADS)

    Tsventoukh, M. M.

    2014-02-01

    It is shown that a combination of the convex and the concave part of a field line provides a strong stabilizing action against convective (flute-interchange) plasma instability (Tsventoukh 2011 Nucl. Fusion 51 112002). This results in internal peaking of the stable plasma pressure profile that is calculated from the collisionless kinetic stability criterion for any magnetic confinement system with combination of mirrors and cusps. Connection of the convex and concave field line parts results in a reduction of the space charge that drives the unstable E × B motion, as there is an opposite direction of the particle drift in a non-uniform field at convex and concave field lines. The pressure peaking arises at the minimum of the second adiabatic invariant J that takes place at the ‘middle’ of a tandem mirror-cusp transverse cross-section. The position of the minimum in J varies with the particle pitch angle that results in a shift of the peaking position depending on plasma anisotropy. This allows one to improve a stable peaked pressure profile at a convex-concave field by changing the plasma anisotropy over the trap cross-section. Examples of such anisotropic distribution functions are found that give an additional substantial enhancement in the maximal central pressure. Furthermore, the shape of new calculated stable profiles has a wide central plasma layer instead of a narrow peak.

  3. Angular Momentum of Non-axisymmetric Global Modes in Magnetically Confined Plasmas and in Astrophysics*

    NASA Astrophysics Data System (ADS)

    Fei, L.; Coppi, B.

    2008-11-01

    The angular momentum of typical tridimensional modes that can be excited in magnetically confined laboratory plasmas and in astrophysics is evaluated by extending pre-existing theories [1], that are applicable to ``conventional'' waves. For the former case, pressure gradient driven ballooning modes whose frequencies are larger than their growth rates (e.g. given by two-fluid theories) are considered in view of the transport of angular momentum out of the plasma column produced by them. This is one of the processes that can lead to a spontaneous rotation [2], by recoil, of the plasma column. For the latter case tridimensional spiral modes [3] are considered that can be excited in plasma disk structures around compact objects and transport angular momentum radially away from the radius where they co-rotate with the plasma. This allows for mass accretion toward the central object to occur. Two classes of spirals are considered: those that are radially standing and are unstable and those that are convective and oscillatory in the relevant co-rotating frame.*Sponsored in part by the U.S. D.O.E. [1] B. Coppi, M.N. Rosenbluth and R.N. Sudan, Ann. Phys. 55, 2; 207-248 (1969).[2] B. Coppi, Nucl. Fus. 42, 1 (2002).[3]B. Coppi, Paper P1.177, E.P.S. Inter. Conf. (Crete, Greece, 2008).

  4. Scaling of confinement with isotopic content in deuterium and tritium plasmas

    SciTech Connect

    Phillips, C.K.; Scott, S.D.; Bell, M.

    1997-01-01

    The scaling of the electron thermal diffusivity, {chi}{sub e}, with relative gyro radius, {rho}*, has been measured on TFTR by comparing nearly identical ICRF-heated discharges which differ only in hydrogenic isotopic content. Contrary to the gyro-Bohm scaling ({chi}{sub e} {approximately} {chi}{sub B}{rho}*, where {chi}{sub B} is the Bohm diffusivity) observed on DIII-D when {rho}* was varied through a scan of magnetic field strength, {chi}{sub e} is found to scale inversely with {rho}*. Hence, global energy confinement is 8--11% higher in deuterium-tritium plasmas than in deuterium only plasmas, with the higher stored energy attributed almost entirely to the electrons.

  5. Study of Effects of Different Reactions on Plasma Parameters in D-T Magnetic Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Motevalli, S. M.; Fadaei, F.

    2012-09-01

    The consideration of the three main nuclear reactions of the hydrogen isotopes (D(D, n)3He, D(D, p)T and T(D, n)4He) only leads to wrong results for determination of plasma parameters in magnetic confinement fusion reactors. The nuclear reaction 3He(D, p)4He influences the amount of produced tritium since it makes an important contribution to the charged particle energy deposition and to the temperatures. In this paper, we have considered different nuclear reactions of Deuterium-Tritium (D-T) fusion in tokamak reactor. This study has been carried out on the base of the particle and power balance equations in a zero-dimensional model then plasma parameters have been calculated. Finally, the obtained results have been compared with the theoretical results reported by other researchers.

  6. SXR-XUV Diagnostics for Edge and Core of Magnetically Confined Plasmas

    SciTech Connect

    Stutman, Dan

    2014-09-10

    The present report summarizes the results obtained during a one-year extension of DoE grant “SXR-XUV Diagnostics for Edge and Core of Magnetically Confined Plasmas”, at Johns Hopkins University, aimed at completing the development of a new type of magnetic fusion plasma diagnostic, the XUV Transmission Grating Imaging Radiometer (TGIR). The TGIR enables simultaneous spatially and spectrally resolved measurements of the XUV/VUV radiated power from impurities in fusion plasmas, with high speed. The instrument was successfully developed and qualified in the laboratory and in experiments on a tokamak. Its future applications will be diagnostic of the impurity content and transport in the divertor and edge of advanced magnetic fusion experiments, such as NSTX Upgrade.

  7. Ion distribution in the hot spot of an inertial confinement fusion plasma

    NASA Astrophysics Data System (ADS)

    Tang, Xianzhu; Guo, Zehua; Berk, Herb

    2012-10-01

    Maximizing the fusion gain of inertial confinement fusion (ICF) for inertial fusion energy (IFE) applications leads to the standard scenario of central hot spot ignition followed by propagating burn wave through the cold/dense assembled fuel. The fact that the hot spot is surrounded by cold but dense fuel layer introduces subtle plasma physics which requires a kinetic description. Here we perform Fokker-Planck calculations and kinetic PIC simulations for an ICF plasma initially in pressure balance but having large temperature gradient over a narrow transition layer. The loss of the fast ion tail from the hot spot, which is important for fusion reactivity, is quantified by Fokker-Planck models. The role of electron energy transport and the ambipolar electric field is investigated via kinetic simulations and the fluid moment models. The net effect on both hot spot ion temperature and the ion tail distribution, and hence the fusion reactivity, is elucidated.

  8. D-T gamma-to-neutron branching ratio determined from inertial confinement fusion plasmas

    SciTech Connect

    Kim, Y.; Mack, J. M.; Herrmann, H. W.; Young, C. S.; Hale, G. M.; Caldwell, S.; Hoffman, N. M.; Evans, S. C.; Sedillo, T. J.; McEvoy, A.; Langenbrunner, J.; Hsu, H. H.; Huff, M. A.; Batha, S.; Horsfield, C. J.; Rubery, M. S.; Garbett, W. J.; Stoeffl, W.; Grafil, E.; Bernstein, L.; and others

    2012-05-15

    A new deuterium-tritium (D-T) fusion gamma-to-neutron branching ratio [{sup 3}H(d,{gamma}){sup 5}He/{sup 3}H(d,n){sup 4}He] value of (4.2 {+-} 2.0) Multiplication-Sign 10{sup -5} was recently reported by this group [Y. Kim et al. Phys. Rev. C (submitted)]. This measurement, conducted at the OMEGA laser facility located at the University of Rochester, was made for the first time using inertial confinement fusion (ICF) plasmas. Neutron-induced backgrounds are significantly reduced in these experiments as compared to traditional beam-target accelerator-based experiments due to the short pulse nature of ICF implosions and the use of gas Cherenkov {gamma}-ray detectors with fast temporal responses and inherent energy thresholds. It is expected that this ICF-based measurement will help resolve the large and long-standing inconsistencies in previously reported accelerator-based values, which vary by a factor of approximately 30. The reported value at ICF conditions was determined by averaging the results of two methods: (1) a direct measurement of ICF D-T {gamma}-ray and neutron emissions using absolutely calibrated detectors and (2) a separate cross-calibration against the better known D-{sup 3}He gamma-to-proton branching ratio [{sup 3}He(d, {gamma}){sup 5}Li/{sup 3}He(d,p){sup 4}He]. Here we include a detailed explanation of these results, and introduce as a corroborative method an in-situ{gamma}-ray detector calibration using neutron-induced {gamma}-rays. Also, by extending the established techniques to two additional series of implosions with significantly different ion temperatures, we test the branching ratio dependence on ion temperature. The data show a D-T branching ratio is nearly constant over the temperature range 2-9 keV. These studies motivate further investigation into the {sup 5}He and {sup 5}Li systems resulting from D-T and D-{sup 3}He fusion, respectively, and result in improved ICF {gamma}-ray reaction history diagnosis at the National Ignition

  9. Sheared-flow induced confinement transition in a linear magnetized plasma

    SciTech Connect

    Zhou, S.; Heidbrink, W. W.; Boehmer, H.; McWilliams, R.; Carter, T. A.; Vincena, S.; Friedman, B.; Schaffner, D.

    2012-01-15

    A magnetized plasma cylinder (12 cm in diameter) is induced by an annular shape obstacle at the Large Plasma Device [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)]. Sheared azimuthal flow is driven at the edge of the plasma cylinder through edge biasing. Strong fluctuations of density and potential ({delta}n/n{approx}e{delta}{phi}/kT{sub e}{approx}0.5) are observed at the plasma edge, accompanied by a large density gradient (L{sub n}={nabla}lnn{sup -1}{approx}2cm) and shearing rate ({gamma}{approx}300kHz). Edge turbulence and cross-field transport are modified by changing the bias voltage (V{sub bias}) on the obstacle and the axial magnetic field (B{sub z}) strength. In cases with low V{sub bias} and large B{sub z}, improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by ExB drift dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer. In cases with higher bias voltage or smaller B{sub z}, large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m=1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient (drift wave like) and flow shear (Kelvin-Helmholtz like) at the plasma edge.

  10. Distinct turbulence sources and confinement features in the spherical tokamak plasma regime

    DOE PAGESBeta

    Wang, W. X.; Ethier, S.; Ren, Y.; Kaye, S.; Chen, J.; Startsev, E.; Lu, Z.

    2015-10-30

    New turbulence contributions to plasma transport and confinement in the spherical tokamak (ST) regime are identified through nonlinear gyrokinetic simulations. The drift wave Kelvin-Helmholtz (KH) mode characterized by intrinsic mode asymmetry is shown to drive significant ion thermal transport in strongly rotating national spherical torus experiment (NSTX) L-modes. The long wavelength, quasi-coherent dissipative trapped electron mode (TEM) is destabilized in NSTX H-modes despite the presence of strong E x B shear, providing a robust turbulence source dominant over collisionless TEM. Dissipative trapped electron mode (DTEM)-driven transport in the NSTX parametric regime is shown to increase with electron collision frequency, offeringmore » one possible source for the confinement scaling observed in experiments. There exists a turbulence-free regime in the collision-induced collisionless trapped electron mode to DTEM transition for ST plasmas. In conclusion, this predicts a natural access to a minimum transport state in the low collisionality regime that future advanced STs may cover.« less

  11. Distinct turbulence sources and confinement features in the spherical tokamak plasma regime

    SciTech Connect

    Wang, W. X.; Ethier, S.; Ren, Y.; Kaye, S.; Chen, J.; Startsev, E.; Lu, Z.

    2015-10-30

    New turbulence contributions to plasma transport and confinement in the spherical tokamak (ST) regime are identified through nonlinear gyrokinetic simulations. The drift wave Kelvin-Helmholtz (KH) mode characterized by intrinsic mode asymmetry is shown to drive significant ion thermal transport in strongly rotating national spherical torus experiment (NSTX) L-modes. The long wavelength, quasi-coherent dissipative trapped electron mode (TEM) is destabilized in NSTX H-modes despite the presence of strong E x B shear, providing a robust turbulence source dominant over collisionless TEM. Dissipative trapped electron mode (DTEM)-driven transport in the NSTX parametric regime is shown to increase with electron collision frequency, offering one possible source for the confinement scaling observed in experiments. There exists a turbulence-free regime in the collision-induced collisionless trapped electron mode to DTEM transition for ST plasmas. In conclusion, this predicts a natural access to a minimum transport state in the low collisionality regime that future advanced STs may cover.

  12. NBI fast ion confinement in the helical core of MAST hybrid-like plasmas

    NASA Astrophysics Data System (ADS)

    Pfefferlé, D.; Graves, J. P.; Cooper, W. A.; Misev, C.; Chapman, I. T.; Turnyanskiy, M.; Sangaroon, S.

    2014-06-01

    Energetic ions are found to be transported strongly from the core of MAST hybrid-like plasmas during long-lived mode (LLM) magnetohydrodynamic activity. The resulting impact on the neutral beam ion deposition and concurrent current drive is modelled using the guiding-centre approximation in the internal kinked magnetic topology. General coordinate guiding-centre equations are extended for this purpose. It is found that the kinked core spirals around the position of strongest ionization, which remains geometrically centred, so that a large fraction of the population is deposited in the high shear external region where the plasma is almost axisymmetric. Those particles ionized in the low shear region exhibit exotic drift motion due to the strongly non-axisymmetric equilibrium, periodically passing near the magnetic axis and then reflected by the boundary of the kinked equilibrium, which in this respect acts as a confining pinch. Broad agreement is found against experimental measurement of fast ion particle confinement degradation as the MAST LLM amplitude varies.

  13. Study of Plasma Liner Driven Magnetized Target Fusion Via Advanced Simulations

    SciTech Connect

    Samulyak, Roman V.; Parks, Paul

    2013-08-31

    The feasibility of the plasma liner driven Magnetized Target Fusion (MTF) via terascale numerical simulations will be assessed. In the MTF concept, a plasma liner, formed by merging of a number (60 or more) of radial, highly supersonic plasma jets, implodes on the target in the form of two compact plasma toroids, and compresses it to conditions of the fusion ignition. By avoiding major difficulties associated with both the traditional laser driven inertial confinement fusion and solid liner driven MTF, the plasma liner driven MTF potentially provides a low-cost and fast R&D path towards the demonstration of practical fusion energy. High fidelity numerical simulations of full nonlinear models associated with the plasma liner MTF using state-of-art numerical algorithms and terascale computing are necessary in order to resolve uncertainties and provide guidance for future experiments. At Stony Brook University, we have developed unique computational capabilities that ideally suite the MTF problem. The FronTier code, developed in collaboration with BNL and LANL under DOE funding including SciDAC for the simulation of 3D multi-material hydro and MHD flows, has beenbenchmarked and used for fundamental and engineering problems in energy science applications. We have performed 3D simulations of converging supersonic plasma jets, their merger and the formation of the plasma liner, and a study of the corresponding oblique shock problem. We have studied the implosion of the plasma liner on the magnetized plasma target by resolving Rayleigh-Taylor instabilities in 2D and 3D and other relevant physics and estimate thermodynamic conditions of the target at the moment of maximum compression and the hydrodynamic efficiency of the method.

  14. Effects of front-surface target structures on properties of relativistic laser-plasma electrons.

    PubMed

    Jiang, S; Krygier, A G; Schumacher, D W; Akli, K U; Freeman, R R

    2014-01-01

    We report the results of a study of the role of prescribed geometrical structures on the front of a target in determining the energy and spatial distribution of relativistic laser-plasma electrons. Our three-dimensional particle-in-cell simulation studies apply to short-pulse, high-intensity laser pulses, and indicate that a judicious choice of target front-surface geometry provides the realistic possibility of greatly enhancing the yield of high-energy electrons while simultaneously confining the emission to narrow (<5°) angular cones.

  15. MAGNETICALLY CONFINED INTERSTELLAR HOT PLASMA IN THE NUCLEAR BULGE OF OUR GALAXY

    SciTech Connect

    Nishiyama, Shogo; Kwon, Jungmi; Tamura, Motohide; Yasui, Kazuki; Nagata, Tetsuya; Yoshikawa, Tatsuhito; Uchiyama, Hideki; Schödel, Rainer; Hatano, Hirofumi; Sato, Shuji; Sugitani, Koji; Suenaga, Takuya

    2013-06-01

    The origin of the Galactic center diffuse X-ray emission (GCDX) is still under intense investigation. In particular, the interpretation of the hot (kT ≈ 7 keV) component of the GCDX, characterized by the strong Fe 6.7 keV line emission, has been contentious. If the hot component originates from a truly diffuse interstellar plasma, not a collection of unresolved point sources, such plasma cannot be gravitationally bound, and its regeneration would require a huge amount of energy. Here, we show that the spatial distribution of the GCDX does not correlate with the number density distribution of an old stellar population traced by near-infrared light, strongly suggesting a significant contribution of the diffuse interstellar plasma. Contributions of the old stellar population to the GCDX are implied to be ∼50% and ∼20% in the nuclear stellar disk (NSD) and nuclear star cluster, respectively. For the NSD, a scale height of 0.°32 ± 0.°02 is obtained for the first time from the stellar number density profiles. We also show the results of the extended near-infrared polarimetric observations in the central 3° × 2° region of our Galaxy, and confirm that the GCDX region is permeated by a large scale, toroidal magnetic field (MF) as previously claimed. Together with observed MF strengths close to energy equipartition, the hot plasma could be magnetically confined, reducing the amount of energy required to sustain it.

  16. An efficient computational approach for evaluating radiation flux for laser driven inertial confinement fusion targets

    NASA Astrophysics Data System (ADS)

    Li, Haiyan; Huang, Yunbao; Jiang, Shaoen; Jing, Longfei; Ding, Yongkun

    2015-08-01

    Radiation flux computation on the target is very important for laser driven Inertial Confinement Fusion, and view-factor based equation models (MacFarlane, 2003; Srivastava et al., 2000) are often used to compute this radiation flux on the capsule or samples inside the hohlraum. However, the equation models do not lead to sparse matrices and may involve an intensive solution process when discrete mesh elements become smaller and the number of equations increases. An efficient approach for the computation of radiation flux is proposed in this paper, in which, (1) symmetric and positive definite properties are achieved by transformation, and (2) an efficient Cholesky factorization algorithm is applied to significantly accelerate such equations models solving process. Finally, two targets on a laser facility built in China are considered to validate the computing efficiency of present approach. The results show that the radiation flux computation can be accelerated by a factor of 2.

  17. First Observation of the High Field Side Sawtooth Crash and Heat Transfer during Driven Reconnection Processes in Magnetically Confined Plasmas

    SciTech Connect

    Park, HK; Luhmann, NC; Donne, AJH; Classen, IGJ; Domier, CW; Mazzucato, E; Munsat, T; van de Pol, MJ; Xia, Z

    2005-12-01

    High resolution (temporal and spatial), two-dimensional images of electron temperature fluctuations during sawtooth oscillations were employed to study driven reconnection processes in magnetically confined toroidal plasmas. The combination of kink and local pressure driven instabilities leads to an "X-point" reconnection process that is localized in the toroidal and poloidal planes. The reconnection is not always confined to the magnetic surfaces with minimum energy. The heat transport process from the core is demonstrated to be highly collective rather than stochastic.

  18. GPUbased, Microsecond Latency, HectoChannel MIMO Feedback Control of Magnetically Confined Plasmas

    NASA Astrophysics Data System (ADS)

    Rath, Nikolaus

    Feedback control has become a crucial tool in the research on magnetic confinement of plasmas for achieving controlled nuclear fusion. This thesis presents a novel plasma feedback control system that, for the first time, employs a Graphics Processing Unit (GPU) for microsecond-latency, real-time control computations. This novel application area for GPU computing is opened up by a new system architecture that is optimized for low-latency computations on less than kilobyte sized data samples as they occur in typical plasma control algorithms. In contrast to traditional GPU computing approaches that target complex, high-throughput computations with massive amounts of data, the architecture presented in this thesis uses the GPU as the primary processing unit rather than as an auxiliary of the CPU, and data is transferred from A-D/D-A converters directly into GPU memory using peer-to-peer PCI Express transfers. The described design has been implemented in a new, GPU-based control system for the High-Beta Tokamak - Extended Pulse (HBT-EP) device. The system is built from commodity hardware and uses an NVIDIA GeForce GPU and D-TACQ A-D/D-A converters providing a total of 96 input and 64 output channels. The system is able to run with sampling periods down to 4 μs and latencies down to 8 μs. The GPU provides a total processing power of 1.5 x 1012 floating point operations per second. To illustrate the performance and versatility of both the general architecture and concrete implementation, a new control algorithm has been developed. The algorithm is designed for the control of multiple rotating magnetic perturbations in situations where the plasma equilibrium is not known exactly and features an adaptive system model: instead of requiring the rotation frequencies and growth rates embedded in the system model to be set a priori, the adaptive algorithm derives these parameters from the evolution of the perturbation amplitudes themselves. This results in non-linear control

  19. Confinement time of electron plasma approaching magnetic pumping transport limit in small aspect ratio C-shaped torus

    NASA Astrophysics Data System (ADS)

    Lachhvani, Lavkesh; Pahari, Sambaran; Goswami, Rajiv; Bajpai, Manu; Yeole, Yogesh; Chattopadhyay, P. K.

    2016-06-01

    A long confinement time of electron plasma, approaching magnetic pumping transport limit, has been observed in SMARTEX-C (a small aspect ratio partial torus with R o / a ˜ 1.59 ). Investigations of the growth rate reveal that they are governed by instabilities like resistive wall destabilization, ion driven instabilities, and electron-neutral collisions. Successful confinement of electron plasmas exceeding > 1 × 10 5 poloidal E → × B → rotations lasting for nearly 2.1 ± 0.1 s is achieved by suppressing these instabilities. The confinement time has been estimated in two ways: (a) from the frequency scaling of the linear diocotron mode launched from sections of the wall that are also used as capacitive probes and (b) by dumping the plasma onto a charge collector at different hold times.

  20. Fabrication and testing of gas filled targets for large scale plasma experiments on Nova

    SciTech Connect

    Stone, G.F.; Spragge, M.; Wallace, R.J.; Rivers, C.J. |

    1995-03-06

    An experimental campaign on the Nova laser was started in July 1993 to study one st of target conditions for the point design of the National Ignition Facility (NIF). The targets were specified to investigate the current NIF target conditions--a plasma of {approximately}3 keV electron temperature and an electron density of {approximately}1.0 E + 21 cm{sup {minus}3}. A gas cell target design was chosen to confine as gas of {approximately}0.01 cm{sup 3} in volume at {approximately} 1 atmosphere. This paper will describe the major steps and processes necessary in the fabrication, testing and delivery of these targets for shots on the Nova Laser at LLNL.

  1. Effects of acute temperature change, confinement and housing on plasma corticosterone in water snakes, Nerodia sipedon (Colubridae: Natricinae).

    PubMed

    Sykes, Kyle Lea; Klukowski, Matthew

    2009-03-01

    Body temperature affects many aspects of reptilian behavior and physiology, but its effect on hormonal secretion has been little studied, especially in snakes. Major objectives of this study were to determine if acute changes in body temperature during confinement influenced plasma corticosterone levels and if initial body temperatures upon capture in the field were related to baseline corticosterone levels in water snakes (Nerodia sipedon). Water snakes were bled upon capture in the field and after one hour of confinement in a cooled, control, or heated incubator. Since little is known about the potential metabolic changes in response to stress in reptiles, plasma triglyceride levels were also measured. Upon completion of the field study, snakes were housed for 5-8 days without food to determine the effect of chronic stress on both corticosterone and triglyceride levels. Plasma corticosterone concentrations were measured using enzyme-linked immunosorbant assay (ELISA) and plasma triglycerides were determined enzymatically. In the field, experimental alterations of body temperature during confinement had no effect on corticosterone levels. Similarly, there was no correlation between initial body temperature and baseline plasma corticosterone concentrations. However, post-confinement corticosterone levels were approximately three-times greater in females than males. Plasma triglyceride levels were not affected by temperature treatment, confinement, or sex. Compared to field values, both baseline and post-confinement corticosterone levels were elevated after the chronic stress of short-term laboratory housing but triglyceride levels decreased. Overall, these results indicate that sex but not body temperature has a major influence on the adrenocortical stress response in Nerodia sipedon.

  2. Fusion reactivity, confinement, and stability of neutral-beam heated plasmas in TFTR and other tokamaks

    SciTech Connect

    Park, Hyeon, K.; Sabbagh, S.A.

    1996-05-01

    The hypothesis that the heating beam fueling profile shape connects the edge condition and improved core confinement and fusion reactivity is extensively studied on TFTR and applied to other tokamaks. The derived absolute scalings based on beam fueling profile shape for the stored energy and neutron yield can be applied to the deuterium discharges at different major radii in TFTR. These include Supershot, High poloidal beta, L-mode, and discharges with a reversed shear (RS) magnetic configuration. These scalings are also applied to deuterium-tritium discharges. The role of plasma parameters, such as plasma current, Isdo2(p), edge safety factor, qsdo5(a), and toroidal field, Bsdo2(T), in the performance and stability of the discharges is explicitly studied. Based on practical and externally controllable plasma parameters, the limitation and optimization of fusion power production of the present TFTR is investigated and a path for a discharge condition with fusion power gain, Q > 1 is suggested based on this study. Similar physics interpretation is provided for beam heated discharges on other major tokamaks.

  3. Particle and momentum confinement in tokamak plasmas with unbalanced neutral beam injection and strong rotation

    SciTech Connect

    Malik, M.A.

    1988-01-01

    There is a self-consistent theory of the effects of neutral beam injection on impurity transport in tokamak plasmas. The theory predicts that co-injection drives impurities outward and that counter-injection enhances the normally inward flow of impurities. The theory was applied to carry out a detailed analysis of the large experimental database from the PLT and the ISX-B tokamaks. The theory was found to generally model the experimental data quite well. It is, therefore, concluded that neutral beam co-injection can drive impurities outward to achieve clean central plasmas and a cool radiating edge. Theoretical predictions for future thermonuclear reactors such as INTOR, TIBER II, and ITER indicated that neutral beam driven flow reversal might be an effective impurity control method if the rate of beam momentum deposited per plasma ion is adequate. The external momentum drag, which is a pivotal concept in impurity flow reversal theory, is correctly predicted by the gyroviscous theory of momentum confinement. The theory was applied to analyze experimental data from the PLT and the PDX tokamaks with exact experimental conditions. The theory was found to be in excellent agreement with experiment over a wide range of parameters. It is, therefore, possible to formulate the impurity transport theory from first principles, without resort to empiricism.

  4. Study of improved confinement by a stepwise increase of the input heating power for tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Asif, Muhammad; Mohamed, Mabruka; Kim, Eun-Jin

    2016-09-01

    This paper is an extension of the brief study by Sarah Douglas et al. [Phys. Plasmas 20 (2013) 114504] where in the study a sinusoidal perturbation of the heating power has been studied. In this paper a stepwise increase of the heating power and its influence on the L-H transition are studied. Using a function, Atanh(t/T) for the transition of input heating power for tokamak plasmas, i.e. the addition of the perturbation, Atanh(t/T), to constant power q0 is shown to promote the confinement, leading to the L-H transition at a lower value of q0, as compared to the case of constant q0 without the Atanh(t/T) perturbation. It is seen that the input heating power Q that consists of constant part q0 in addition to a function Atanh(t/T) provides the L-H transition for relatively small A and much wider range values of 1/T as compared to Sarah Douglas et al. [Phys. Plasmas 20 (2013) 114504].

  5. Investigations into the Seeding of Instabilities due to X-ray Preheat in Beryllium-Based Inertial Confinement Fusion Targets

    NASA Astrophysics Data System (ADS)

    Loomis, Eric

    2009-11-01

    The geometry of inertial confinement fusion (ICF) capsules makes them susceptible to various types of hydrodynamic instabilities at different stages during an ICF implosion. From the beginnings of ICF research, it has been known that grain-level anisotropy and defects could be a primary source of instability seeding in solid capsules. This has steered ICF designs to include amorphous materials such as plastic; however, the benefits of low-Z metallic materials, i.e. beryllium, has kept these materials the focus of much research. Recently, experiments were conducted at the Trident laser facility to measure dynamic surface roughening from hard x-ray preheat. M-band emission from laser produced gold plasma was used to heat beryllium targets with different amounts of copper doping to temperatures comparable to National Ignition Facility (NIF) preheat levels. Temporal and spectral x-ray diagnostics were used to estimate the target heating, which was also predicted by multi-dimensional radiation hydrodynamics calculations. Wave profiles of varying complexity due to differences in copper doping were observed with free surface line imaging velocity interferometry. Dynamic roughening measurements were made on the surface away from the plasma at discrete times up to 8 ns after the beginning of the drive pulse using a surface displacement interferometer with nanometer scale sensitivity. Undoped, large-grained targets were measured to roughen between 15 and 50 nm rms depending on variations in x-ray absorption through the target thickness. Fine-grained, copper-doped targets were observed to roughen near the sensitivity limit of the interferometer and approached the Rev2 NIC design point of 0.9 nm. The results of this combined experimental and modeling effort have shed light on the effects of high-Z doping and microstructural refinement on the dynamics of differential thermal expansion and have shown that current NIF capsule designs using beryllium are very effective in reducing

  6. The effect of magnetic fields and ablative stabilization on Rayleigh-Taylor unstable inertial confinement fusion plasmas

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bhuvana; Tang, Xian-Zhu

    2013-10-01

    It has long been expected that Rayleigh-Taylor instabilities (RTI) in inertial confinement fusion (ICF) can generate magnetic fields at the gas-ice interface and at the ice-ablator interface during the deceleration phase of target implosion. The focus here is on the gas-ice interface where the temperature gradient is the largest. Nonlinear evolution of RTI leads to undesirable mixing of hot and cold plasmas and enhances target energy loss. RTI is also expected to generate magnetic fields via the Biermann battery effect which mitigate energy loss by decreasing electron thermal conduction at the gas-ice interface. The Hall-magnetohydrodynamics model is used to self-consistently study the generation and growth of magnetic fields in RTI. Externally applied magnetic fields grow due to the MHD dynamo and can result in mix mitigation in addition to significant electron thermal conductivity mitigation. Electron thermal conductivity can cause ablation of the ice into the gas, leading to ablative stabilization of RTI. Mitigation of electron thermal conductivity (and energy loss) in the presence of magnetic fields has a conflicting effect with the ablative stabilization of RTI brought about due to electron thermal conductivity. A study of this conflicting effect will be presented.

  7. Topics on the Formation and Stability of Magnetic Mirror Confined Plasmas.

    NASA Astrophysics Data System (ADS)

    Wickham, Michael Gordon

    We have investigated two methods of creating a magnetic mirror confined plasma. The first method used the direct cross-field injection of a potassium plasma into a magnetic mirror, and the second applied ion-cyclotron -resonance heating (ICRH) to a barium Q-machine plasma in a simple axisymmetric mirror field. The latter procedure provided a plasma which was particularly suitable for the investigation of MHD stability and kinetic microstability. In the first method, a beam of potassium plasma of 10('12)cm('-3). density was formed in a continuous magnetoplasmadynamic arc. source. This beam was then injected into a mirror configuration from. a direction transverse to the magnetic field. The self-induced polarization and subsequent E(' )X(' )B drift of the beam allowed the plasma to fill the magnetic mirror. A density of 10('12)cm('-3) was obtained when insulating end plugs were used, a slightly reduced value when the beam was injected into a straight solenoidal field, and a lower limit of 10('11)cm('-3) if the end plugs were made conducting. The temperature of the trapped plasma corresponded to approximately two thirds of the energy in the initial directed motion of the beam. We discuss these results qualitatively in terms of the polarization-drift model of Schmidt. The possible application of this injection technique to the fueling of tandem-mirror end cells is described briefly. The second series of experiments studied a low (beta), high density, collisionless, barium plasma which was energized by the application of ICRH in a simple axisymmetric mirror. The barium ions were thereby heated from an initial perpendicular temperature of 0.2 eV to 3-5 eV. We then measured, with laser induced resonance-fluorescence techniques, the ion velocity distribution under the influence of ICRH. In particular, we examined the temporal evolution of two components of the ion velocity distribution, f(v(,x),t) and f(v(,(VBAR)(VBAR)),t), in a fixed magnetic field configuration. The ion

  8. Oligomers of the ATPase EHD2 confine caveolae to the plasma membrane through association with actin

    PubMed Central

    Stoeber, Miriam; Stoeck, Ina Karen; Hänni, Christine; Bleck, Christopher Karl Ernst; Balistreri, Giuseppe; Helenius, Ari

    2012-01-01

    Caveolae are specialized domains present in the plasma membrane (PM) of most mammalian cell types. They function in signalling, membrane regulation, and endocytosis. We found that the Eps-15 homology domain-containing protein 2 (EHD2, an ATPase) associated with the static population of PM caveolae. Recruitment to the PM involved ATP binding, interaction with anionic lipids, and oligomerization into large complexes (60–75S) via interaction of the EH domains with intrinsic NPF/KPF motifs. Hydrolysis of ATP was essential for binding of EHD2 complexes to caveolae. EHD2 was found to undergo dynamic exchange at caveolae, a process that depended on a functional ATPase cycle. Depletion of EHD2 by siRNA or expression of a dominant-negative mutant dramatically increased the fraction of mobile caveolar vesicles coming from the PM. Overexpression of EHD2, in turn, caused confinement of cholera toxin B in caveolae. The confining role of EHD2 relied on its capacity to link caveolae to actin filaments. Thus, EHD2 likely plays a key role in adjusting the balance between PM functions of stationary caveolae and the role of caveolae as vesicular carriers. PMID:22505029

  9. Oligomers of the ATPase EHD2 confine caveolae to the plasma membrane through association with actin.

    PubMed

    Stoeber, Miriam; Stoeck, Ina Karen; Hänni, Christine; Bleck, Christopher Karl Ernst; Balistreri, Giuseppe; Helenius, Ari

    2012-05-16

    Caveolae are specialized domains present in the plasma membrane (PM) of most mammalian cell types. They function in signalling, membrane regulation, and endocytosis. We found that the Eps-15 homology domain-containing protein 2 (EHD2, an ATPase) associated with the static population of PM caveolae. Recruitment to the PM involved ATP binding, interaction with anionic lipids, and oligomerization into large complexes (60-75S) via interaction of the EH domains with intrinsic NPF/KPF motifs. Hydrolysis of ATP was essential for binding of EHD2 complexes to caveolae. EHD2 was found to undergo dynamic exchange at caveolae, a process that depended on a functional ATPase cycle. Depletion of EHD2 by siRNA or expression of a dominant-negative mutant dramatically increased the fraction of mobile caveolar vesicles coming from the PM. Overexpression of EHD2, in turn, caused confinement of cholera toxin B in caveolae. The confining role of EHD2 relied on its capacity to link caveolae to actin filaments. Thus, EHD2 likely plays a key role in adjusting the balance between PM functions of stationary caveolae and the role of caveolae as vesicular carriers. PMID:22505029

  10. Customizing electron confinement in plasma-assembled Si/AlN nanodots for solar cell applications

    SciTech Connect

    Huang, S. Y.; Xu, S.; Arulsamy, A. Das; Xu, M.; Cvelbar, U.; Mozetic, M.; Ostrikov, K.

    2009-12-15

    Size-uniform Si nanodots (NDs) are synthesized on an AlN buffer layer at low Si(111) substrate temperatures using inductively coupled plasma-assisted magnetron sputtering deposition. High-resolution electron microscopy reveals that the sizes of the Si NDs range from 9 to 30 nm. Room-temperature photoluminescence (PL) spectra indicate that the energy peak shifts from 738 to 778 nm with increasing the ND size. In this system, the quantum confinement effect is fairly strong even for relatively large (up to 25 nm in diameter) NDs, which is promising for the development of the next-generation all-Si tandem solar cells capable of effectively capturing sunlight photons with the energies between 1.7 (infrared: large NDs) and 3.4 eV (ultraviolet: small NDs). The strength of the resulting electron confinement in the Si/AlN ND system is evaluated and justified by analyzing the measured PL spectra using the ionization energy theory approximation.

  11. Inertially confined fusion plasmas dominated by alpha-particle self-heating

    NASA Astrophysics Data System (ADS)

    Hurricane, O. A.; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Haan, S.; Hinkel, D. E.; Berzak Hopkins, L. F.; Jones, O.; Kritcher, A. L.; Le Pape, S.; Ma, T.; Macphee, A. G.; Milovich, J. L.; Moody, J.; Pak, A.; Park, H.-S.; Patel, P. K.; Ralph, J. E.; Robey, H. F.; Ross, J. S.; Salmonson, J. D.; Spears, B. K.; Springer, P. T.; Tommasini, R.; Albert, F.; Benedetti, L. R.; Bionta, R.; Bond, E.; Bradley, D. K.; Caggiano, J.; Celliers, P. M.; Cerjan, C.; Church, J. A.; Dylla-Spears, R.; Edgell, D.; Edwards, M. J.; Fittinghoff, D.; Barrios Garcia, M. A.; Hamza, A.; Hatarik, R.; Herrmann, H.; Hohenberger, M.; Hoover, D.; Kline, J. L.; Kyrala, G.; Kozioziemski, B.; Grim, G.; Field, J. E.; Frenje, J.; Izumi, N.; Gatu Johnson, M.; Khan, S. F.; Knauer, J.; Kohut, T.; Landen, O.; Merrill, F.; Michel, P.; Moore, A.; Nagel, S. R.; Nikroo, A.; Parham, T.; Rygg, R. R.; Sayre, D.; Schneider, M.; Shaughnessy, D.; Strozzi, D.; Town, R. P. J.; Turnbull, D.; Volegov, P.; Wan, A.; Widmann, K.; Wilde, C.; Yeamans, C.

    2016-08-01

    Alpha-particle self-heating, the process of deuterium-tritium fusion reaction products depositing their kinetic energy locally within a fusion reaction region and thus increasing the temperature in the reacting region, is essential for achieving ignition in a fusion system. Here, we report new inertial confinement fusion experiments where the alpha-particle heating of the plasma is dominant with the fusion yield produced exceeding the fusion yield from the work done on the fuel (pressure times volume change) by a factor of two or more. These experiments have achieved the highest yield (26 +/- 0.5 kJ) and stagnation pressures (≍220 +/- 40 Gbar) of any facility-based inertial confinement fusion experiments, although they are still short of the pressures required for ignition on the National Ignition Facility (~300-400 Gbar). These experiments put us in a new part of parameter space that has not been extensively studied so far because it lies between the no-alpha-particle-deposition regime and ignition.

  12. Mean and Oscillating Plasma Flows and Turbulence Interactions across the L-H Confinement Transition

    SciTech Connect

    Conway, G. D.; Angioni, C.; Ryter, F.; Sauter, P.; Vicente, J.

    2011-02-11

    A complex interaction between turbulence driven ExB zonal flow oscillations, i.e., geodesic acoustic modes (GAMs), the turbulence, and mean equilibrium flows is observed during the low to high (L-H) plasma confinement mode transition in the ASDEX Upgrade tokamak. Below the L-H threshold at low densities a limit-cycle oscillation forms with competition between the turbulence level and the GAM flow shearing. At higher densities the cycle is diminished, while in the H mode the cycle duration becomes too short to sustain the GAM, which is replaced by large amplitude broadband flow perturbations. Initially GAM amplitude increases as the H-mode transition is approached, but is then suppressed in the H mode by enhanced mean flow shear.

  13. Probing Leader Cells in Endothelial Collective Migration by Plasma Lithography Geometric Confinement

    PubMed Central

    Yang, Yongliang; Jamilpour, Nima; Yao, Baoyin; Dean, Zachary S.; Riahi, Reza; Wong, Pak Kin

    2016-01-01

    When blood vessels are injured, leader cells emerge in the endothelium to heal the wound and restore the vasculature integrity. The characteristics of leader cells during endothelial collective migration under diverse physiological conditions, however, are poorly understood. Here we investigate the regulation and function of endothelial leader cells by plasma lithography geometric confinement generated. Endothelial leader cells display an aggressive phenotype, connect to follower cells via peripheral actin cables and discontinuous adherens junctions, and lead migrating clusters near the leading edge. Time-lapse microscopy, immunostaining, and particle image velocimetry reveal that the density of leader cells and the speed of migrating clusters are tightly regulated in a wide range of geometric patterns. By challenging the cells with converging, diverging and competing patterns, we show that the density of leader cells correlates with the size and coherence of the migrating clusters. Collectively, our data provide evidence that leader cells control endothelial collective migration by regualting the migrating clusters. PMID:26936382

  14. Stability properties and fast ion confinement of hybrid tokamak plasma configurations

    NASA Astrophysics Data System (ADS)

    Graves, J. P.; Brunetti, D.; Pfefferle, D.; Faustin, J. M. P.; Cooper, W. A.; Kleiner, A.; Lanthaler, S.; Patten, H. W.; Raghunathan, M.

    2015-11-01

    In hybrid scenarios with flat q just above unity, extremely fast growing tearing modes are born from toroidal sidebands of the near resonant ideal internal kink mode. New scalings of the growth rate with the magnetic Reynolds number arise from two fluid effects and sheared toroidal flow. Non-linear saturated 1/1 dominant modes obtained from initial value stability calculation agree with the amplitude of the 1/1 component of a 3D VMEC equilibrium calculation. Viable and realistic equilibrium representation of such internal kink modes allow fast ion studies to be accurately established. Calculations of MAST neutral beam ion distributions using the VENUS-LEVIS code show very good agreement of observed impaired core fast ion confinement when long lived modes occur. The 3D ICRH code SCENIC also enables the establishment of minority RF distributions in hybrid plasmas susceptible to saturated near resonant internal kink modes.

  15. Probing Leader Cells in Endothelial Collective Migration by Plasma Lithography Geometric Confinement.

    PubMed

    Yang, Yongliang; Jamilpour, Nima; Yao, Baoyin; Dean, Zachary S; Riahi, Reza; Wong, Pak Kin

    2016-03-03

    When blood vessels are injured, leader cells emerge in the endothelium to heal the wound and restore the vasculature integrity. The characteristics of leader cells during endothelial collective migration under diverse physiological conditions, however, are poorly understood. Here we investigate the regulation and function of endothelial leader cells by plasma lithography geometric confinement generated. Endothelial leader cells display an aggressive phenotype, connect to follower cells via peripheral actin cables and discontinuous adherens junctions, and lead migrating clusters near the leading edge. Time-lapse microscopy, immunostaining, and particle image velocimetry reveal that the density of leader cells and the speed of migrating clusters are tightly regulated in a wide range of geometric patterns. By challenging the cells with converging, diverging and competing patterns, we show that the density of leader cells correlates with the size and coherence of the migrating clusters. Collectively, our data provide evidence that leader cells control endothelial collective migration by regualting the migrating clusters.

  16. Probing Leader Cells in Endothelial Collective Migration by Plasma Lithography Geometric Confinement

    NASA Astrophysics Data System (ADS)

    Yang, Yongliang; Jamilpour, Nima; Yao, Baoyin; Dean, Zachary S.; Riahi, Reza; Wong, Pak Kin

    2016-03-01

    When blood vessels are injured, leader cells emerge in the endothelium to heal the wound and restore the vasculature integrity. The characteristics of leader cells during endothelial collective migration under diverse physiological conditions, however, are poorly understood. Here we investigate the regulation and function of endothelial leader cells by plasma lithography geometric confinement generated. Endothelial leader cells display an aggressive phenotype, connect to follower cells via peripheral actin cables and discontinuous adherens junctions, and lead migrating clusters near the leading edge. Time-lapse microscopy, immunostaining, and particle image velocimetry reveal that the density of leader cells and the speed of migrating clusters are tightly regulated in a wide range of geometric patterns. By challenging the cells with converging, diverging and competing patterns, we show that the density of leader cells correlates with the size and coherence of the migrating clusters. Collectively, our data provide evidence that leader cells control endothelial collective migration by regualting the migrating clusters.

  17. Dust confinement and dust-acoustic waves in weakly magnetized anodic plasmas

    SciTech Connect

    Trottenberg, Thomas; Block, Dietmar; Piel, Alexander

    2006-04-15

    Experiments on dust-acoustic waves (DAW) in a magnetized anodic plasma are presented for the regime of low collisionality. The dust trapping and the self-excited and synchronized DAW dynamics are studied. Based on Langmuir and emissive probe measurements the dust confinement is found to be well described with respect to size, stability, and position of the dust cloud by an effective potential well formed by ion drag and Coulomb forces. Moreover, the measurements indicate the necessity for a kinetic model for the wave dispersion. By means of singular value decomposition the local wavelengths and growth rates of the waves are measured systematically. It is found that the measured mean wave number is well described by kinetic theory, while the theoretical growth rates overestimate the experiments. A novel observation for the DAW is a systematic variation of the wavelength inside the dust cloud.

  18. Quiescent double barrier high-confinement mode plasmas in the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Burrell, K. H.; Austin, M. E.; Brennan, D. P.; DeBoo, J. C.; Doyle, E. J.; Fenzi, C.; Fuchs, C.; Gohil, P.; Greenfield, C. M.; Groebner, R. J.; Lao, L. L.; Luce, T. C.; Makowski, M. A.; McKee, G. R.; Moyer, R. A.; Petty, C. C.; Porkolab, M.; Rettig, C. L.; Rhodes, T. L.; Rost, J. C.; Stallard, B. W.; Strait, E. J.; Synakowski, E. J.; Wade, M. R.; Watkins, J. G.; West, W. P.

    2001-05-01

    High-confinement (H-mode) operation is the choice for next-step tokamak devices based either on conventional or advanced tokamak physics. This choice, however, comes at a significant cost for both the conventional and advanced tokamaks because of the effects of edge localized modes (ELMs). ELMs can produce significant erosion in the divertor and can affect the beta limit and reduced core transport regions needed for advanced tokamak operation. Experimental results from DIII-D [J. L. Luxon et al., Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] this year have demonstrated a new operating regime, the quiescent H-mode regime, which solves these problems. We have achieved quiescent H-mode operation that is ELM-free and yet has good density and impurity control. In addition, we have demonstrated that an internal transport barrier can be produced and maintained inside the H-mode edge barrier for long periods of time (>3.5 s or >25 energy confinement times τE), yielding a quiescent double barrier regime. By slowly ramping the input power, we have achieved βNH89=7 for up to 5 times the τE of 150 ms. The βNH89 values of 7 substantially exceed the value of 4 routinely achieved in the standard ELMing H mode. The key factors in creating the quiescent H-mode operation are neutral beam injection in the direction opposite to the plasma current (counter injection) plus cryopumping to reduce the density. Density and impurity control in the quiescent H mode is possible because of the presence of an edge magnetohydrodynamic (MHD) oscillation, the edge harmonic oscillation, which enhances the edge particle transport while leaving the energy transport unaffected.

  19. Precision Manufacturing of Inertial Confinement Fusion Double Shell Laser Targets for OMEGA

    SciTech Connect

    Amendt, P A; Bono, M J; Hibbard, R L; Castro, C; Bennett, D W

    2003-11-21

    Double shell targets have been built by Lawrence Livermore National Laboratory (LLNL) for inertial confinement fusion (ICF) experiments on the Omega laser at the University of Rochester and as a prelude to similar experiments on NIF. Of particular interest to ICF studies are high-precision double shell implosion targets for demonstrating thermonuclear ignition without the need for cryogenic preparation. Because the ignition tolerance to interface instabilities is rather low, the manufacturing requirements for smooth surface finishes and shell concentricity are particularly strict. This paper describes a deterministic approach to manufacturing and controlling error sources in each component. Included is the design philosophy of why certain manufacturing techniques were chosen to best reduce the errors within the target. The manufacturing plan developed for this effort created a deterministic process that, once proven, is repeatable. By taking this rigorous approach to controlling all error sources during the manufacture of each component and during assembly, we have achieved the overall 5 {micro}m dimensional requirement with sub-micron surface flaws. Strengths and weaknesses of the manufacturing process will be discussed.

  20. The effect of target materials on colliding laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Yang, Zefeng; Wu, Jian; Han, Jiaxun; Wei, Wenfu; Jia, Shenli; Qiu, Aici

    2016-04-01

    In laser ablation, nanosecond to femtosecond lasers with a wide range of laser power densities are used. During ablation, the result of collisions between two plasmas is of interest to many researchers in inertial confinement fusion and nuclear astrophysics. In this paper, the collisions of two seed plasmas ablated from planar target surfaces of different target materials (Al, Cu, and W) were studied with temporal-spatially resolved imaging and spectroscopy. The initial relative velocities and densities of the seed plasmas were measured, and then the collisional parameters were calculated to evaluate the degree of the collisions. In addition, spatially resolved spectra were analyzed to study the influences of materials on the temporal-spatial distribution of atom or ions. The results indicated that under the same laser intensity, the high atomic number (Z) material had a small value of collisionality parameter, mostly because of its heavy ion mass. Higher laser intensity would increase the initial relative velocity of seed plasmas, resulting in a lower collision frequency. In addition, the distribution of the ions from seed plasmas was influenced by the stagnation layer plasmas.

  1. Development of Field-Reversed Configuration Plasma Gun Formation Techniques for Magnetized Target Fusion

    NASA Astrophysics Data System (ADS)

    Lynn, Alan; Gilmore, Mark; Wynkoop, Tyler; Intrator, Thomas; Weber, Thomas

    2012-10-01

    Magnetized Target Fusion (MTF) is an innovative approach for a relatively fast and cheap path to the production of fusion energy that utilizes magnetic confinement to assist in the compression of a hot plasma to thermonuclear conditions by an external driver. Los Alamos National Laboratory (LANL) is currently pursing demonstration of the MTF concept via compression of an FRC (field-reversed configuration) plasma by a metal liner z-pinch in conjunction with the Air Force Research Laboratory in Albuquerque, NM. A key physics issue for the FRC as an MTF target lies in the initial pre-ionization (PI) stage. The PI formation process determines the amount of magnetic flux that can be trapped to form the FRC. This trapped flux plays an important role in the FRC's final equilibrium, transport, and stability properties. It also provides the route to greatest potential gains in FRC lifetime, which is essential to provide enough time to translate and compress the FRC effectively. In conjunction with LANL we plan to test and characterize a new system to improve the initial PI plasma formation. This system will use an array of plasma guns to form the initial plasma. Initial characterization of the plasma gun behavior will be presented.

  2. Principles of separation: indications and therapeutic targets for plasma exchange.

    PubMed

    Williams, Mark E; Balogun, Rasheed A

    2014-01-01

    Extracorporeal "blood purification," mainly in the form of hemodialysis has been a major portion of the clinical activity of many nephrologists for the past 5 decades. A possibly older procedure, therapeutic plasma exchange, separates and then removes plasma as a method of removing pathogenic material from the patient. In contrast to hemodialysis, therapeutic plasma exchange preferentially removes biologic substances of high molecular weight such as autoantibodies or alloantibodies, antigen-antibody complexes, and Ig paraproteins. These molecular targets may be cleared through two alternative procedures: centrifugal separation and membrane separation. This review presents operational features of each procedure, with relevance to the nephrologist. Kinetics of removal of these plasma constituents are based on the principles of separation by the apheresis technique and by features specific to each molecular target, including their production and compartmentalization in the body. Molecular targets for common renal conditions requiring therapeutic plasma exchange are also discussed in detail.

  3. Theoretical studies on plasma heating and confinement. Final report, May 4, 1984--May 13, 1988

    SciTech Connect

    Sudan, R.N.

    1993-01-01

    Three principal topics are covered in this final report: Stabilization of low frequency modes of an axisymmetric compact torus plasma confinement system, such as, spheromaks and FRC`S, by a population of large orbit axis encircling energetic ions. Employing an extension of the `energy principle` which utilizes a Vlasov description for the energetic `ion component, it has been demonstrated that short wavelength MHD type modes are stabilized while the long wavelength tilt and precessional modes are marginally stable. The deformation of the equilibrium configuration by the energetic ions results in the stabilization of the tilt mode for spheromaks. Formation of Ion Rings and their coalescence with spheromaks. A two dimensional electromagnetic PIC codes has been developed for the study of ion ring formation and its propagation, deformation and slowing down in a cold plasma. It has been shown that a ring moving at a speed less than the Alfven velocity can merge with a stationary spheromak. Anomalous transport from drift waves in a Tokomak. The Direct Interaction Approximation in used to obtain incremental transport coefficients for particles and heat for drift waves in a Tokomak. It is shown that the transport matrix does not obey Onsager`s principle.

  4. Introduction to Gyrokinetic Theory with Applications in Magnetic Confinement Research in Plasma Physics

    SciTech Connect

    W.M. Tang

    2005-01-03

    The present lecture provides an introduction to the subject of gyrokinetic theory with applications in the area of magnetic confinement research in plasma physics--the research arena from which this formalism was originally developed. It was presented as a component of the ''Short Course in Kinetic Theory within the Thematic Program in Partial Differential Equations'' held at the Fields Institute for Research in Mathematical Science (24 March 2004). This lecture also discusses the connection between the gyrokinetic formalism and powerful modern numerical simulations. Indeed, simulation, which provides a natural bridge between theory and experiment, is an essential modern tool for understanding complex plasma behavior. Progress has been stimulated in particular by the exponential growth of computer speed along with significant improvements in computer technology. The advances in both particle and fluid simulations of fine-scale turbulence and large-scale dynamics have produced increasingly good agreement between experimental observations and computational modeling. This was enabled by two key factors: (i) innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning widely disparate temporal and spatial scales and (ii) access to powerful new computational resources.

  5. Effects of Laser-Plasma Instabilities on Hydro Evolution in Direct-Drive Inertial Confinement Fusion

    NASA Astrophysics Data System (ADS)

    Li, J.; Hu, S. X.; Ren, C.

    2015-11-01

    Laser-plasma instabilities and hydro evolution of coronal plasmas in an OMEGA EP long-scale-length experiment with planar targets are studied with particle-in-cell (PIC) and hydrodynamics simulations. Plasma and laser conditions are first obtained in a DRACO simulation with only inverse-bremsstrahlung absorption. Using these conditions, an OSIRIS simulation is performed to study laser absorption and hot-electron generation caused by laser-plasma instabilities near the quarter-critical region. The obtained PIC information has subsequently been coupled to another DRACO simulation to examine how the laser-plasma instabilities affect the overall hydrodynamics. The results show that the more-realistic laser absorption can increase the electron temperature but only slightly changes the density scale length in the corona. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944, DE-FC02-04ER54789 (Fusion Science Center), and DE-SC0012316.

  6. Magnetized Target Fusion Propulsion: Plasma Injectors for MTF Guns

    NASA Technical Reports Server (NTRS)

    Griffin, Steven T.

    2003-01-01

    To achieve increased payload size and decreased trip time for interplanetary travel, a low mass, high specific impulse, high thrust propulsion system is required. This suggests the need for research into fusion as a source of power and high temperature plasma. The plasma would be deflected by magnetic fields to provide thrust. Magnetized Target Fusion (MTF) research consists of several related investigations into these topics. These include the orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the gun as it relates to plasma initiation and repeatability are under investigation. One of the items under development is the plasma injector. This is a surface breakdown driven plasma generator designed to function at very low pressures. The performance, operating conditions and limitations of these injectors need to be determined.

  7. Identification of new turbulence contributions to plasma transport and confinement in spherical tokamak regime

    DOE PAGESBeta

    Wang, W. X.; Ethier, S.; Ren, Y.; Kaye, S.; Chen, J.; Startsev, E.; Lu, Z.; Li, Z. Q.

    2015-10-15

    Highly distinct features of spherical tokamaks (ST), such as National Spherical Torus eXperiment (NSTX) and NSTX-U, result in a different fusion plasma regime with unique physics properties compared to conventional tokamaks. Nonlinear global gyrokinetic simulations critical for addressing turbulence and transport physics in the ST regime have led to new insights. The drift wave Kelvin-Helmholtz (KH) instability characterized by intrinsic mode asymmetry is identified in strongly rotating NSTX L-mode plasmas. While the strong E x B shear associated with the rotation leads to a reduction in KH/ion temperature gradient turbulence, the remaining fluctuations can produce a significant ion thermal transportmore » that is comparable to the experimental level in the outer core region (with no "transport shortfall"). The other new, important turbulence source identified in NSTX is the dissipative trapped electron mode (DTEM), which is believed to play little role in conventional tokamak regime. Due to the high fraction of trapped electrons, long wavelength DTEMs peaking around kθρs ~ 0.1 are destabilized in NSTX collisionality regime by electron density and temperature gradients achieved there. Surprisingly, the E x B shear stabilization effect on DTEM is remarkably weak, which makes it a major turbulence source in the ST regime dominant over collisionless TEM (CTEM). The latter, on the other hand, is subject to strong collisional and E x B shear suppression in NSTX. DTEM is shown to produce significant particle, energy and toroidal momentum transport, in agreement with experimental levels in NSTX H-modes. Furthermore, DTEM-driven transport in NSTX parametric regime is found to increase with electron collision frequency, providing one possible source for the scaling of confinement time observed in NSTX H-modes. Most interestingly, the existence of a turbulence-free regime in the collision-induced CTEM to DTEM transition, corresponding to a minimum plasma transport in

  8. Particle modelling of magnetically confined oxygen plasma in low pressure radio frequency discharge

    SciTech Connect

    Benyoucef, Djilali; Yousfi, Mohammed

    2015-01-15

    The main objective of this paper is the modelling and simulation of a radio frequency (RF) discharge in oxygen at low pressure and at room temperature, including the effect of crossed electric and magnetic fields for generation and confinement of oxygen plasma. The particle model takes into account one axial dimension along the electric field axis and three velocity components during the Monte Carlo treatment of the collisions between charged particles and background gas. The simulation by this developed code allows us not only to determine the electrodynamics characteristics of the RF discharge, but also to obtain kinetics and energetic description of reactive oxygen plasma at low pressure. These information are very important for the control of the deep reactive-ion etching technology of the silicon to manufacture capacitors with high density and for the deposition thick insulating films or thick metal to manufacture micro-coils. The simulation conditions are as follows: RF peak voltage of 200 V, frequency of 13.56 MHz, crossed magnetic field varying from 0 to 50 Gauss, and oxygen pressure of 13.8 Pa. In the presence of magnetic field, the results show an increase of the plasma density, a decrease of the electron mean energy, and also a reduction of the ratio between electron density and positive ion density. Finally in order to validate, the results are successfully compared with measurements already carried out in the literature. The conditions of comparison are from 100 to 300 V of the peak voltage at 13.56 MHz under a pressure of 13.8 Pa and a gap distance of 2.5 cm.

  9. Particle modelling of magnetically confined oxygen plasma in low pressure radio frequency discharge

    NASA Astrophysics Data System (ADS)

    Benyoucef, Djilali; Yousfi, Mohammed

    2015-01-01

    The main objective of this paper is the modelling and simulation of a radio frequency (RF) discharge in oxygen at low pressure and at room temperature, including the effect of crossed electric and magnetic fields for generation and confinement of oxygen plasma. The particle model takes into account one axial dimension along the electric field axis and three velocity components during the Monte Carlo treatment of the collisions between charged particles and background gas. The simulation by this developed code allows us not only to determine the electrodynamics characteristics of the RF discharge, but also to obtain kinetics and energetic description of reactive oxygen plasma at low pressure. These information are very important for the control of the deep reactive-ion etching technology of the silicon to manufacture capacitors with high density and for the deposition thick insulating films or thick metal to manufacture micro-coils. The simulation conditions are as follows: RF peak voltage of 200 V, frequency of 13.56 MHz, crossed magnetic field varying from 0 to 50 Gauss, and oxygen pressure of 13.8 Pa. In the presence of magnetic field, the results show an increase of the plasma density, a decrease of the electron mean energy, and also a reduction of the ratio between electron density and positive ion density. Finally in order to validate, the results are successfully compared with measurements already carried out in the literature. The conditions of comparison are from 100 to 300 V of the peak voltage at 13.56 MHz under a pressure of 13.8 Pa and a gap distance of 2.5 cm.

  10. Identification of new turbulence contributions to plasma transport and confinement in spherical tokamak regime

    SciTech Connect

    Wang, W. X.; Ethier, S.; Ren, Y.; Kaye, S.; Chen, J.; Startsev, E.; Lu, Z.; Li, Z. Q.

    2015-10-15

    Highly distinct features of spherical tokamaks (ST), such as National Spherical Torus eXperiment (NSTX) and NSTX-U, result in a different fusion plasma regime with unique physics properties compared to conventional tokamaks. Nonlinear global gyrokinetic simulations critical for addressing turbulence and transport physics in the ST regime have led to new insights. The drift wave Kelvin-Helmholtz (KH) instability characterized by intrinsic mode asymmetry is identified in strongly rotating NSTX L-mode plasmas. While the strong E x B shear associated with the rotation leads to a reduction in KH/ion temperature gradient turbulence, the remaining fluctuations can produce a significant ion thermal transport that is comparable to the experimental level in the outer core region (with no "transport shortfall"). The other new, important turbulence source identified in NSTX is the dissipative trapped electron mode (DTEM), which is believed to play little role in conventional tokamak regime. Due to the high fraction of trapped electrons, long wavelength DTEMs peaking around kθρs ~ 0.1 are destabilized in NSTX collisionality regime by electron density and temperature gradients achieved there. Surprisingly, the E x B shear stabilization effect on DTEM is remarkably weak, which makes it a major turbulence source in the ST regime dominant over collisionless TEM (CTEM). The latter, on the other hand, is subject to strong collisional and E x B shear suppression in NSTX. DTEM is shown to produce significant particle, energy and toroidal momentum transport, in agreement with experimental levels in NSTX H-modes. Furthermore, DTEM-driven transport in NSTX parametric regime is found to increase with electron collision frequency, providing one possible source for the scaling of confinement time observed in NSTX H-modes. Most interestingly, the existence of a turbulence-free regime in the collision-induced CTEM to DTEM transition, corresponding to a minimum plasma

  11. Real viscosity effects in inertial confinement fusion target deuterium–tritium micro-implosions

    SciTech Connect

    Mason, R. J. Kirkpatrick, R. C.; Faehl, R. J.

    2014-02-15

    We report on numerical studies of real viscous effects on the implosion characteristics of imploded DT micro-targets. We use the implicit ePLAS code to perform 2D simulations of spherical and slightly ellipsoidal DT shells on DT gas filled ∼40 μm diameter voids. Before their final implosions the shells have been nearly adiabatically compressed up to 10{sup 2} or 10{sup 3} g/cm{sup 3} densities. While the use of conventional artificial viscosity can lead to high central densities for initially spherical shells, we find that a real physical viscosity from ion-ion collisions can give a high (>20 keV) central temperature but severely reduced central density (<200 g/cm{sup 3}), while the elliptical shells evidence p = 2 distortion of the heated central fuel region. These results suggest that the general use of artificial viscosities in Inertial Confinement Fusion (ICF) modeling may have lead to overly optimistic yields for current NIF targets and that polar direct drive with more energy for the imploding capsule may be needed for ultimate ICF success.

  12. Influence of the radial profile of the electric potential on the confinement of a high-{beta} two-component plasma in a gas-dynamic trap

    SciTech Connect

    Soldatkina, E. I.; Bagryansky, P. A.; Solomakhin, A. L.

    2008-04-15

    One of the most important problems to be studied in the gas-dynamic trap (GDT) facility is the investigation of MHD stability and cross-field transport in a plasma with a relatively high value of {beta} = {pi}p/B{sup 2}. Recent experiments demonstrated that the radial electric field produced in the plasma by using radial limiters and coaxial end plasma collectors improves plasma stability in axisymmetric magnetic mirror systems without applying special MHD stabilizers. The experimental data presented in this work show that stable plasma confinement can be achieved by producing a radial potential drop across a narrow region near the plasma boundary. Creating radial electric fields of strength 15-40 V/cm causes a shear plasma flow, thereby substantially increasing the plasma confinement time. When all the radial electrodes were grounded, the confinement was unstable and the plasma confinement time was much shorter than the characteristic time of plasma outflow through the magnetic mirrors. Measurements of cross-field plasma fluxes with the use of a specially designed combined probe show that, in confinement modes with differential plasma rotation, transverse particle losses are negligibly small as compared to longitudinal ones and thus can be ignored. It is also shown that, when the GDT plasma is in electric contact with the radial limiters and end collectors, the growth rate of interchange instability decreases considerably; such a contact, however, does not ensure complete MHD stability when the electrodes are at the same potential.

  13. Mammalian plasma membrane proteins as potential biomarkers and drug targets.

    PubMed

    Rucevic, Marijana; Hixson, Douglas; Josic, Djuro

    2011-06-01

    Defining the plasma membrane proteome is crucial to understand the role of plasma membrane in fundamental biological processes. Change in membrane proteins is one of the first events that take place under pathological conditions, making plasma membrane proteins a likely source of potential disease biomarkers with prognostic or diagnostic potential. Membrane proteins are also potential targets for monoclonal antibodies and other drugs that block receptors or inhibit enzymes essential to the disease progress. Despite several advanced methods recently developed for the analysis of hydrophobic proteins and proteins with posttranslational modifications, integral membrane proteins are still under-represented in plasma membrane proteome. Recent advances in proteomic investigation of plasma membrane proteins, defining their roles as diagnostic and prognostic disease biomarkers and as target molecules in disease treatment, are presented.

  14. Automatic targeting of plasma spray gun

    DOEpatents

    Abbatiello, Leonard A.; Neal, Richard E.

    1978-01-01

    A means for monitoring the material portion in the flame of a plasma spray gun during spraying operations is provided. A collimated detector, sensitive to certain wavelengths of light emission, is used to locate the centroid of the material with each pass of the gun. The response from the detector is then relayed to the gun controller to be used to automatically realign the gun.

  15. Effect of the laser wavelength: A long story of laser-plasma interaction physics for Inertial Confinement Fusion Teller Medal Lecture

    NASA Astrophysics Data System (ADS)

    Labaune, Christine

    2013-11-01

    Laser-driven Inertial Confinement Fusion (ICF) relies on the use of high-energy laser beams to compress and ignite a thermonuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources-combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-term program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.

  16. Effect of the laser wavelength: A long story of laser-plasma interaction physics for Inertial Confinement Fusion Teller Medal Lecture

    NASA Astrophysics Data System (ADS)

    Labaune, Christine

    2016-10-01

    Laser-driven Inertial Confinement Fusion (ICF) relies on the use of high-energy laser beams to compress and ignite a the1monuclear fuel with the ultimate goal of producing energy. Fusion is the holy grail of energy sources-combining abundant fuel with no greenhouse gas emissions, minimal waste products and a scale that can meet mankind's long-term energy demands. The quality and the efficiency of the coupling of the laser beams with the target are an essential step towards the success of laser fusion. A long-te1m program on laser-plasma interaction physics has been pursued to understand the propagation and the coupling of laser pulses in plasmas for a wide range of parameters.

  17. The mitigating effect of magnetic fields on Rayleigh-Taylor unstable inertial confinement fusion plasmas

    SciTech Connect

    Srinivasan, Bhuvana; Tang, Xian-Zhu

    2013-05-15

    Rayleigh-Taylor (RT) instabilities at interfaces of disparate mass densities have long been known to generate magnetic fields during inertial confinement fusion implosions. An externally applied magnetic field can also be efficiently amplified by RT instabilities. The focus here is on magnetic field generation and amplification at the gas-ice interface which is RT unstable during the deceleration phase of the implosion. RT instabilities lead to undesirable mix of hot and cold plasmas which enhances thermal energy loss and tends to produce a more massive warm-spot instead of a hot-spot. Two mechanisms are shown here to mitigate the thermal energy loss from the hot-spot. The first mechanism is the reduction of electron thermal conductivity with interface-aligned magnetic fields. This can occur through self-generated magnetic fields via the Biermann battery effect as well as through externally applied magnetic fields that undergo an exponential growth via the stretch-and-fold magnetohydrodynamic dynamo. Self-generated magnetic fields during RT evolution can result in a factor of 2−10 decrease in the electron thermal conductivity at the gas-ice interface, while externally applied magnetic fields that are compressed to 6–1000 T at the onset of deceleration (corresponding to pre-implosion external fields of 0.06–10 T) could result in a factor of 2–500 reduction in electron thermal conductivity at the gas-ice interface. The second mechanism to mitigate thermal energy loss from the hot-spot is to decrease the interface mixing area between the hot and cold plasmas. This is achieved through large external magnetic fields of 1000 T at the onset of deceleration which damp short-wavelength RT modes and long-wavelength Kelvin-Helmholtz modes thus significantly slowing the RT growth and reducing mix.

  18. The field line map approach for simulations of magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Stegmeir, Andreas; Coster, David; Maj, Omar; Hallatschek, Klaus; Lackner, Karl

    2016-01-01

    Predictions of plasma parameters in the edge and scrape-off layer of tokamaks is difficult since most modern tokamaks have a divertor and the associated separatrix causes the usually employed field/flux-aligned coordinates to become singular on the separatrix/X-point. The presented field line map approach avoids such problems as it is based on a cylindrical grid: standard finite-difference methods can be used for the discretisation of perpendicular (w.r.t. magnetic field) operators, and the characteristic flute mode property (k∥ ≪k⊥) of structures is exploited computationally via a field line following discretisation of parallel operators which leads to grid sparsification in the toroidal direction. This paper is devoted to the discretisation of the parallel diffusion operator (the approach taken is very similar to the flux-coordinate independent (FCI) approach which has already been adopted to a hyperbolic problem (Ottaviani, 2011; Hariri, 2013)). Based on the support operator method, schemes are derived which maintain the self-adjointness property of the parallel diffusion operator on the discrete level. These methods have very low numerical perpendicular diffusion compared to a naive discretisation which is a critical issue since magnetically confined plasmas exhibit a very strong anisotropy. Two different versions of the discrete parallel diffusion operator are derived: the first is based on interpolation where the order of interpolation and therefore the numerical diffusion is adjustable; the second is based on integration and is advantageous in cases where the field line map is strongly distorted. The schemes are implemented in the new code GRILLIX, and extensive benchmarks and numerous examples are presented which show the validity of the approach in general and GRILLIX in particular.

  19. Confined trapped-alpha behavior in TFTR deuterium-tritium plasmas

    SciTech Connect

    Medley, S.S.; Budny, R.V.; Redi, M.H.; Roquemore, A.L.; White, R.B.; Duong, H.H.; Fisher, R.K.; Petrov, M.P.; Gorelenkov, N.N.

    1997-10-01

    Confined trapped-alpha energy spectra and differential radial density profiles in TFTR D-T plasmas are obtained with the Pellet Charge-eXchange (PCX) diagnostic which measures high energy (E{sub {alpha}} = 0.5--3.5 MeV), trapped alphas (v{sub {parallel}}/v = - 0.048) at a single time slice ({Delta}t {approximately} 1 msec) with a spatial resolution of {Delta}r {approximately} 5 cm. Tritons produced in D-D plasmas and RF-driven ion tails (H, {sup 3}He or T) were also observed and energetic tritium ion tail measurements will be discussed. PCX alpha and triton energy spectra extending up to their birth energies were measured in the core of MHD-quiescent discharges where the expected classical slowing down and pitch angle scattering effects are not complicated by stochastic ripple diffusion and sawtooth activity. Both the shape of the measured alpha and triton energy distributions and their density ratios are in good agreement with TRANSP predictions, indicating that the PCX measurements are consistent with classical thermalization of the fusion-generated alphas and tritons. From calculations, these results set an upper limit on possible anomalous radial diffusion for trapped alphas of D{sub {alpha}} {le} 0.01 m{sup 2}s{sup {minus}1}. Outside the core, where the trapped alphas are influenced by stochastic ripple diffusion effects, the PCX measurements are consistent with the functional dependence of the Goldston-White-Boozer stochastic ripple threshold on the alpha energy and the q-profile. In the presence of strong sawtooth activity, the PCX diagnostic observes significant redistribution of the alpha signal radial profile wherein alphas are depleted in the core and redistributed to well outside the q = 1 radius, but apparently not beyond the energy-dependent stochastic ripple loss boundary.

  20. Microspot target development with seeded and patterned plasma polymers

    SciTech Connect

    Letts, S.A.; Miller, D.E.; Corley, R.A.; Tillotson, T.M.; Witt, L.A.

    1984-12-10

    A new class of targets for laser fusion experiments was fabricated using plasma-deposition and etching technology. Plasma polymer coatings seeded with silicon or sulfur were deposited as 300..mu..m diameter microspots inside holes of equal diameter in a pure hydrocarbon polymer film. The target was designed to study large-scale plasma instabilities and measure the temperature and density histories of laser induced plasmas. The microspot target required three new development: freestanding stress-free CH films, technology to define and form holes in CH films, and development of seeded films deposited as 300..mu..m diameter discs, nested tightly in the precision holes. Hydrocarbon films were deposited by plasma polymerization or by solution casting (polystyrene in dichloromethane) onto potassium-chloide-coated glass slides. Holes were defined either by masking with a 300..mu..m diameter disc or by reactive ion etching through a washer mask. Sulfur or silicon seeded CH polymer microspots were deposited through a mask using plasma polymerization. Seeded polymer films were prepared with compositions as high as 12 atomic percent, with most diagnostic targets made with 2 a/o. Silicon seeded polymers, when deposited at 750 mtorr (100 Pa) pressure, wer transparent and colorless.

  1. APPARATUS FOR TRAPPING ENERGETIC CHARGED PARTICLES AND CONFINING THE RESULTING PLASMA

    DOEpatents

    Gibson, G.; Jordan, W.C.; Lauer, E.J.

    1963-04-01

    The present invention relates to a plasma-confining device and a particle injector therefor, the device utilizing a generally toroidal configuration with magnetic fields specifically tailored to the associated injector. The device minimizes the effects of particle end losses and particle drift to the walls with a relatively simple configuration. More particularly, the magnetic field configuration is created by a continuous array of circular, mirror field coils, disposed side-by- side, in particularly spaced relation, to form an endless, toroidal loop. The resulting magnetic field created therein has the appearance of a bumpy'' torus, from which is derived the name Bumpy Torus.'' One of the aforementioned coils is split transverse to its axis, and injection of particles is accomplished along a plane between the halves of such modified coil. The guiding center of the particles follows a constant magnetic field in the plane for a particular distance within the torus, to move therefrom onto a precessional surface which does not intersect the point of injection. (AEC)

  2. Mechanism for magnetic field generation and growth in Rayleigh-Taylor unstable inertial confinement fusion plasmas

    SciTech Connect

    Srinivasan, Bhuvana; Tang Xianzhu

    2012-08-15

    Rayleigh-Taylor instabilities (RTI) in inertial confinement fusion (ICF) implosions are expected to generate magnetic fields at the gas-ice interface and at the ice-ablator interface. The focus here is on the gas-ice interface where the temperature gradient is the largest. A Hall-MHD model is used to study the magnetic field generation and growth for 2-D single-mode and multimode RTI in a stratified two-fluid plasma, the two fluids being ions and electrons. Self-generated magnetic fields are observed and these fields grow as the RTI progresses via the {nabla}n{sub e} Multiplication-Sign {nabla}T{sub e} term in the generalized Ohm's law. Srinivasan et al.[Phys. Rev. Lett. 108, 165002 (2012)] present results of the magnetic field generation and growth, and some scaling studies in 2-dimensions. The results presented here study the mechanism behind the magnetic field generation and growth, which is related to fluid vorticity generation by RTI. The magnetic field wraps around the bubbles and spikes and concentrates in flux bundles at the perturbed gas-ice interface where fluid vorticity is large. Additionally, the results of Srinivasan et al.[Phys. Rev. Lett. 108, 165002 (2012)] are described in greater detail. Additional scaling studies are performed to determine the growth of the self-generated magnetic field as a function of density, acceleration, perturbation wavelength, Atwood number, and ion mass.

  3. Mechanism for magnetic field generation and growth in Rayleigh-Taylor unstable inertial confinement fusion plasmas

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bhuvana; Tang, Xian-Zhu

    2012-08-01

    Rayleigh-Taylor instabilities (RTI) in inertial confinement fusion (ICF) implosions are expected to generate magnetic fields at the gas-ice interface and at the ice-ablator interface. The focus here is on the gas-ice interface where the temperature gradient is the largest. A Hall-MHD model is used to study the magnetic field generation and growth for 2-D single-mode and multimode RTI in a stratified two-fluid plasma, the two fluids being ions and electrons. Self-generated magnetic fields are observed and these fields grow as the RTI progresses via the ∇ne×∇Te term in the generalized Ohm's law. Srinivasan et al. [Phys. Rev. Lett. 108, 165002 (2012)] present results of the magnetic field generation and growth, and some scaling studies in 2-dimensions. The results presented here study the mechanism behind the magnetic field generation and growth, which is related to fluid vorticity generation by RTI. The magnetic field wraps around the bubbles and spikes and concentrates in flux bundles at the perturbed gas-ice interface where fluid vorticity is large. Additionally, the results of Srinivasan et al. [Phys. Rev. Lett. 108, 165002 (2012)] are described in greater detail. Additional scaling studies are performed to determine the growth of the self-generated magnetic field as a function of density, acceleration, perturbation wavelength, Atwood number, and ion mass.

  4. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    DOE PAGESBeta

    Vold, Erik Lehman; Joglekar, Archis S.; Ortega, Mario I.; Moll, Ryan; Fenn, Daniel; Molvig, Kim

    2015-11-20

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion(ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. In this paper, we have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasmaviscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasmaviscosity andmore » to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasmaviscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Finally, plasmaviscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.« less

  5. Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

    SciTech Connect

    Vold, Erik Lehman; Joglekar, Archis S.; Ortega, Mario I.; Moll, Ryan; Fenn, Daniel; Molvig, Kim

    2015-11-20

    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion(ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. In this paper, we have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasmaviscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasmaviscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasmaviscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Finally, plasmaviscosity reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.

  6. Spatial confinement effects in laser-induced breakdown spectroscopy

    SciTech Connect

    Shen, X. K.; Sun, J.; Ling, H.; Lu, Y. F.

    2007-08-20

    The spatial confinement effects in laser-induced breakdown of aluminum (Al) targets in air have been investigated both by optical emission spectroscopy and fast photography. A KrF excimer laser was used to produce plasmas from Al targets in air. Al atomic emission lines show an obvious enhancement in the emission intensity when a pair of Al-plate walls were placed to spatially confine the plasma plumes. Images of the Al plasma plumes showed that the plasma plumes evolved into a torus shape and were compressed in the Al walls. The mechanism for the confinement effects was discussed using shock wave theory.

  7. A spectral line survey from 17.5–250 nm of plasmas created in a magnetic confinement device

    NASA Astrophysics Data System (ADS)

    McCarthy, K. J.; Zurro, B.; Hollmann, E. M.; Hernández Sánchez, J.; TJ-II team1, the

    2016-11-01

    Spectral emission lines continue to be a powerful tool for studying astrophysical, process, laser-produced, and magnetically confined plasmas, among others. Hence, numerous spectroscopy-based plasma diagnostics, from the x-ray to the infrared, make use of the relative intensity, width, displacement in wavelength, or temporal evolution of such emission lines emitted by the atoms and ions present in such plasmas. In this work, a spectral line survey, from 17.5–250 nm, is presented for electron cyclotron resonance heated (ECRH) and neutral beam injection (NBI) heated plasmas created and maintained in the TJ-II stellarator, a medium-sized magnetically confined plasma device. In these plasmas, for which hydrogen, deuterium or helium have been used as the working gas, central electron temperatures and densities up to 1 keV and 5 × 1019 m‑3, respectively, are achieved. This work is a compilation of the identified spectral emission lines emitted by the working gas as well by the intrinsic and injected impurity ions in the above wavelength range. For this, spectra were recorded, over the past fifteen years of TJ-II operation, using a 1 m focal length normal incidence spectrometer equipped with a charge-coupled detector at its output focal plane. In total, almost 400 spectral emission lines from eighteen different elements have been identified using a number of atomic line emission databases.

  8. ANALYSIS OF DATA FROM Z-PINCH MTF TARGET PLASMA EXPERIMENTS

    SciTech Connect

    F. WYSOCKI; J. TACCETTI; ET AL

    1999-04-01

    The Los Alamos National Laboratory Colt facility has been used to create target plasma for Magnetized Target Fusion (MTF). The primary results regarding magnetic field, plasma density, plasma temperature, and hot plasma lifetime are summarized and the suitability of these plasma targets for MTF is assessed.

  9. Hydrodynamic simulations of long-scale-length plasmas for two-plasmon-decay planar-target experiments on the NIF

    NASA Astrophysics Data System (ADS)

    Solodov, A. A.; Rosenberg, M. J.; Myatt, J. F.; Epstein, R.; Regan, S. P.; Seka, W.; Shaw, J.; Hohenberger, M.; Bates, J. W.; Moody, J. D.; Ralph, J. E.; Turnbull, D. P.; Barrios, M. A.

    2016-05-01

    The two-plasmon-decay (TPD) instability can be detrimental for direct-drive inertial confinement fusion because it generates high-energy electrons that can preheat the target, thereby reducing target performance. Hydrodynamic simulations to design a new experimental platform to investigate TPD and other laser-plasma instabilities relevant to direct-drive-ignition implosions at the National Ignition Facility are presented. The proposed experiments utilize planar plastic targets with an embedded Mo layer to characterize generation of hot electrons through Mo Kα fluorescence and hard x-ray emission. Different laser-irradiation geometries approximate conditions near both the equator and the pole of a polar-direct-drive implosion.

  10. Radio Frequency (RF) Trap for Confinement of Antimatter Plasmas Using Rotating Wall Electric Fields

    NASA Technical Reports Server (NTRS)

    Sims, William Herbert, III; Pearson, J. Boise

    2004-01-01

    Perturbations associated with a rotating wall electric field enable the confinement of ions for periods approaching weeks. This steady state confinement is a result of a radio frequency manipulation of the ions. Using state-of-the-art techniques it is shown that radio frequency energy can produce useable manipulation of the ion cloud (matter or antimatter) for use in containment experiments. The current research focuses on the improvement of confinement systems capable of containing and transporting antimatter.

  11. Local regulation of interchange turbulence in a dipole-confined plasma torus using current-collection feedback

    SciTech Connect

    Roberts, T. M. Mauel, M. E. Worstell, M. W.

    2015-05-15

    Turbulence in plasma confined by a magnetic dipole is dominated by interchange fluctuations with complex dynamics and short spatial coherence. We report the first use of local current-collection feedback to modify, amplify, and suppress these fluctuations. The spatial extent of turbulence regulation is limited to a correlation length near the collector. Changing the gain and phase of collection results in power either extracted from or injected into the turbulence. The measured plasma response shows some agreement with calculations of the linear response of global interchange-like MHD and entropy modes to current-collection feedback.

  12. BX-U linear trap for one-way production and confinement of Li+ and e- plasmas

    NASA Astrophysics Data System (ADS)

    Himura, Haruhiko

    2016-03-01

    A modified version of the Penning-Malmberg trap was developed wherein both positive and negative harmonic potential wells were created by using multi-ring electrodes. The sequence of particle injection, particle trapping, and plasma extraction from the potential wells was controlled by a set of switching circuits. All the guns launching charged particles were collected together in one side of the linear trap. Nevertheless, pure electron (e-) and lithium-ion (Li+) plasmas were not only separately produced on the machine axis but also confined simultaneously. Preliminary data show that for B ≈ 0.13 T the e- plasma lasted for 15 s and the Li+ plasma lasted for ~ 4 s.

  13. Characterization of magnetically confined low-pressure plasmas produced by an electromagnetic field in argon-acetylene mixtures

    NASA Astrophysics Data System (ADS)

    Makdessi, G. Al; Margot, J.; Clergereaux, R.

    2016-10-01

    Dust particles formation was investigated in magnetically confined low-pressure plasma produced in argon-acetylene mixtures. The plasma characteristics were measured in order to identify the species involved in the dust particles formation. Their dependence on the operating conditions including magnetic field intensity, acetylene fraction in the gas mixture and operating pressure was examined. In contrast with noble gases, in the presence of acetylene, the electron temperature increases with the magnetic field intensity, indicating additional charged particles losses in the plasma. Indeed, in these conditions, larger hydrocarbon ions are produced leading to the formation of dust particles in the plasma volume. The observed dependence of positive ion mass distribution and density and relative negative ion density on the operating parameters suggests that the dust particles are formed through different pathways, where negative and positive ions are both involved in the nucleation.

  14. Wave excitation by nonlinear coupling among shear Alfvén waves in a mirror-confined plasma

    SciTech Connect

    Ikezoe, R. Ichimura, M.; Okada, T.; Hirata, M.; Yokoyama, T.; Iwamoto, Y.; Sumida, S.; Jang, S.; Takeyama, K.; Yoshikawa, M.; Kohagura, J.; Shima, Y.; Wang, X.

    2015-09-15

    A shear Alfvén wave at slightly below the ion-cyclotron frequency overcomes the ion-cyclotron damping and grows because of the strong anisotropy of the ion temperature in the magnetic mirror configuration, and is called the Alfvén ion-cyclotron (AIC) wave. Density fluctuations caused by the AIC waves and the ion-cyclotron range of frequencies (ICRF) waves used for ion heating have been detected using a reflectometer in a wide radial region of the GAMMA 10 tandem mirror plasma. Various wave-wave couplings are clearly observed in the density fluctuations in the interior of the plasma, but these couplings are not so clear in the magnetic fluctuations at the plasma edge when measured using a pick-up coil. A radial dependence of the nonlinearity is found, particularly in waves with the difference frequencies of the AIC waves; bispectral analysis shows that such wave-wave coupling is significant near the core, but is not so evident at the periphery. In contrast, nonlinear coupling with the low-frequency background turbulence is quite distinct at the periphery. Nonlinear coupling associated with the AIC waves may play a significant role in the beta- and anisotropy-limits of a mirror-confined plasma through decay of the ICRF heating power and degradation of the plasma confinement by nonlinearly generated waves.

  15. High-speed repetitive pellet injector for plasma fueling of magnetic confinement fusion devices

    SciTech Connect

    Combs, S.K.; Baylor, L.R.; Foust, C.R.

    1993-11-01

    The projected fueling requirements of future magnetic confinement devices for controlled thermonuclear research [e.g., the International Thermonuclear Experimental Reactor (ITER)] indicate that a flexible plasma fueling capability is required. This includes a mix of traditional gas puffing and low- and high-velocity deuterium-tritium pellets. Conventional pellet injectors (based on light gas guns or centrifugal accelerators) can reliably provide frozen hydrogen pellets (1- to 6-mm-diam sizes tested) up to {approximately}1.3-km/s velocity at the appropriate pellet fueling rates (1 to 10 Hz or greater). For long-pulse operation in a higher velocity regime (>2 km/s), an experiment in collaboration between Oak Ridge National Laboratory (ORNL) and ENEA Frascati is under way. This activity will be carried out in the framework of a collaborative agreement between the US Department of Energy and European Atomic Energy Community -- ENEA Association. In this experiment, an existing ORNL hydrogen extruder (equipped with a pellet chambering mechanism/gun barrel assembly) and a Frascati two-stage light gas gun driver have been combined on a test facility at ORNL. Initial testing has been carried out with single deuterium pellets accelerated up to 2.05 km/s with the two-stage driver; in addition, some preliminary repetitive testing (to commission the diagnostics) was performed at reduced speeds, including sequences at 0.5 to 1 Hz and 10 to 30 pellets. The primary objective of this study is to demonstrate repetitive operation (up to {approximately}1 Hz) with speeds in the 2- to 3-km/s range. In addition, the strength of extruded hydrogen ice as opposed to that produced in situ by direct condensation in pipe guns can be investigated. The equipment and initial experimental results are described.

  16. Experimental Study of the Effects of Lithium Coated Plasma Facing Components on Energy Confinement Time in the CDX-U Device

    NASA Astrophysics Data System (ADS)

    Spaleta, Jeffrey; Zakharov, Leonid; Majeski, Richard; Kaita, Robert; Gray, Timothy

    2006-10-01

    The first ever measurements of energy confinement time for spherical tokamak plasmas in the presence of lithium coated plasma facing components (PFC's) have been made in the CDX-U device. The energy confinement time, as derived from power balance considerations using parameters calculated from plasma equilibria, was as large as 6 milliseconds for Ohmic plasmas in the presence of both solid and liquid lithium PFC's. This represents a significant improvement over baseline plasmas, which typically had energy confinement times of 1 millisecond or less. The energy confinement for plasmas with lithium PFC's also showed an improvement over that expected from the ITER98(y,1) confinement scaling. The improvement in confinement over this scaling correlates with the observed increase in density ``pump-out'', which is indicative of low wall-recycling. Plasma equilibria were calculated using a modified version of the Equilibrium and Stability Code (ESC), and were constrained by measurements made from a collection of magnetic field diagnostics. The ESC was modified to incorporate the first ever implementation of a novel response function technique for in-situ magnetic field diagnostic calibration that is insensitive to toroidal asymmetries and vessel wall currents.

  17. Generating end plug potentials in tandem mirror plasma confinement by heating thermal particles so as to escape low density end stoppering plasmas

    DOEpatents

    Baldwin, David E.; Logan, B. Grant

    1981-01-01

    The invention provides a method and apparatus for raising the potential of a magnetic mirror cell by pumping charged particles of the opposite sign of the potential desired out of the mirror cell through excitation, with the pumping being done by an externally imposed field at the bounce frequency of the above charged particles. These pumped simple mirror cells then provide end stoppering for a center mirror cell for the tandem mirror plasma confinement apparatus. For the substantially complete pumping case, the end plugs of a tandem mirror can be up to two orders of magnitude lower in density for confining a given center mirror cell plasma than in the case of end plugs without pumping. As a result the decrease in recirculating power required to keep the system going, the technological state of the art required, and the capital cost are all greatly lowered.

  18. Generating end plug potentials in tandem mirror plasma confinement by heating thermal particles so as to escape low density end stoppering plasmas

    DOEpatents

    Baldwin, D.E.; Logan, B.G.

    The invention provides a method and apparatus for raising the potential of a magnetic mirror cell by pumping charged particles of the opposite sign of the potential desired out of the mirror cell through excitation, with the pumping being done by an externally imposed field at the bounce frequence of the above charged particles. These pumped simple mirror cells then provide end stoppering for a center mirror cell for the tandem mirror plasma confinement apparatus. For the substantially complete pumping case, the end plugs of a tandem mirror can be up to two orders of magnitude lower in density for confining a given center mirror cell plasma than in the case of end plugs without pumping. As a result the decrease in recirculating power required to keep the system going, the technical state of the art required, and the capital cost are all greatly lowered.

  19. Equilibrium drives of the low and high field side n = 2 plasma response and impact on global confinement

    DOE PAGESBeta

    Paz-Soldan, C.; Logan, N. C.; Haskey, S. R.; Nazikian, R.; Strait, E. J.; Chen, X.; Ferraro, N. M.; King, J. D.; Lyons, B. C.; Park, J. -K.

    2016-03-31

    The nature of the multi-modal n=2 plasma response and its impact on global confinement is studied as a function of the axisymmetric equilibrium pressure, edge safety factor, collisionality, and L-versus H-mode conditions. Varying the relative phase (ΔΦUL) between upper and lower in-vessel coils demonstrates that different n=2 poloidal spectra preferentially excite different plasma responses. These different plasma response modes are preferentially detected on the tokamak high-field side (HFS) or low-field side (LFS) midplanes, have different radial extents, couple differently to the resonant surfaces, and have variable impacts on edge stability and global confinement. In all equilibrium conditions studied, the observedmore » confinement degradation shares the same ΔΦUL dependence as the coupling to the resonant surfaces given by both ideal (IPEC) and resistive (MARS-F) MHD computation. Varying the edge safety factor shifts the equilibrium field-line pitch and thus the ΔΦUL dependence of both the global confinement and the n=2 magnetic response. As edge safety factor is varied, modeling finds that the HFS response (but not the LFS response), the resonant surface coupling, and the edge displacements near the X-point all share the same ΔΦUL dependence. The LFS response magnitude is strongly sensitive to the core pressure and is insensitive to the collisionality and edge safety factor. This indicates that the LFS measurements are primarily sensitive to a pressure-driven kink-ballooning mode that couples to the core plasma. MHD modeling accurately reproduces these (and indeed all) LFS experimental trends and supports this interpretation. In contrast to the LFS, the HFS magnetic response and correlated global confinement impact is unchanged with plasma pressure, but is strongly reduced in high collisionality conditions in both H- and L-mode. This experimentally suggests the bootstrap current drives the HFS response through the kink-peeling mode drive, though

  20. Inertial confinement fusion target component fabrication and technology development support. Annual report, October 1, 1994--September 30, 1995

    SciTech Connect

    Hoppe, M.

    1996-05-01

    On December 30, 1990, the US Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion (ICF) Target Component Fabrication and Technology Development Support contractor. This report documents the technical activities of the period October 1, 1994 through September 30, 1995. During this period, GA was assigned 15 tasks in support of the Inertial Confinement Fusion program and its laboratories. A portion of the effort on these tasks included providing direct ``Onsite Support`` at Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratory Albuquerque (SNLA). The ICF program is anticipating experiments at the National Ignition Facility (NIF) and the OMEGA Upgrade. Both facilities will require capsules containing layered D{sub 2} or deuterium-tritium (D-T) fuel. The authors are part of the National Cryogenic Target Program to create and demonstrate viable ways to generate and characterize cryogenic layers. Progress has been made on ways to both create viable layers and to characterize them. They continued engineering, assembly and testing of equipment for a cryogenic target handling system for University of Rochester`s Laboratory for Laser Energetics (UR/LLE) that will fill, transport, layer, and characterize targets filled with cryogenic fuel, and insert these cryogenic targets into the OMEGA Upgrade target chamber for laser implosion experiments. This report summarizes and documents the technical progress made on these tasks.

  1. XUV spectroscopy of laser plasma from molecular coated metal targets

    NASA Astrophysics Data System (ADS)

    Papanyan, Valeri O.; Nersisyan, Gagik T.; Tittel, Frank K.

    1999-12-01

    Metal targets covered by micrometer layers of metal- phthalocyanines or fullerenes are studied here. An increase in XUV yield due to the optimized absorption of the laser field is reported. Effects of high-temperature plasma rapid expansion (velocity about 106 cm/s) were observed. Moderate power nanosecond and picosecond neodymium lasers are used to produce an incident intensity of 1011 to 1013 W/cm2 on the targets. The plasma electron density was measured by fitting observed spectral profiles to the theoretical profiles. Collisional, Doppler, and Stark broadening mechanisms were considered in the calculations. Our measurement technique permits us to determine the electron density and temperature dependence on distances from the target surface from 1 mm (where Ne approximately equals 1018 cm-3 and Te approximately equals 14 eV are measured for aluminum plasma) up to approximately 5 mm (where Ne targets is greater by a factor of approximately 1.5 than measured from bulk solid metal targets.

  2. XUV spectroscopy of laser plasma from molecular coated metal targets

    NASA Astrophysics Data System (ADS)

    Papanyan, Valeri O.; Nersisyan, Gagik T.; Tittel, Frank K.

    1999-10-01

    Metal targets covered by micrometer layers of metal- phthalocyanines are studied here. An increase in EUV yield due to optimized absorption of the laser field is reported. Effects of high-temperature plasma rapid expansion (velocity about 106 cm/s) were observed. Moderate power nanosecond and picosecond neodymium lasers are used to product an incident intensity of 1011 to 1013 W/cm2 on the targets. The plasma electron density was measured by fitting observed spectral profiles to theoretical profiles. Collisional, Doppler, and Stark broadening mechanisms were considered in the calculations. Our measurement technique makes it possible to determine the electron density and temperature dependence on distances from the target surface from 1 mm (where Ne equals 2.0 (+/- 0.5)1018 cm-3 and Te equals 14 eV are measured for aluminum plasma) up to approximately 5 mm (where Ne targets is greater by a factor of approximately 1.5 than measured from bulk solid metal targets.

  3. Refraction-Enhanced X-ray Radiography for Inertial Confinement Fusion and Laser-Produced Plasma Applications

    SciTech Connect

    Koch, J A; Landen, O L; Kozioziemski, B J; Izumi, N; Dewald, E L; Salmonson, J D; Hammel, B A

    2008-08-26

    We explore various laser-produced plasma and inertial-confinement fusion (ICF) applications of phase-contrast x-ray radiography, and we show how the main features of these enhancements can be considered from a geometrical optics perspective as refraction enhancements. This perspective simplifies the analysis, and often permits simple analytical formulae to be derived that predict the enhancements. We explore a raytrace approach to various material interface applications, and we explore a more general example of refractive bending of x-rays by an implosion plasma. We find that refraction-enhanced x-ray radiography of implosions may provide a means to quantify density differences across shock fronts as well as density variations caused by local heating due to high-Z dopants. We also point out that refractive bending by implosions plasmas can blur fine radiograph features, and can also provide misleading contrast information in area-backlit pinhole imaging experiments unless its effects are taken into consideration.

  4. Formation of Plasma Targets Suitable for Equation of State Experiments.

    NASA Astrophysics Data System (ADS)

    Benage, John

    2005-10-01

    The measurement of the Equation of State (EOS) of materials in the dense-plasma state is difficult. The standard method for measuring EOS relies on the shock driven Hugoniot technique, where the material is initially at standard temperature and pressure and is shocked using a flyer plate. The locus of states produced using this technique is called the standard Hugoniot. However, the states produced do not fall into the regime of dense plasmas, where the EOS of the material is quite uncertain. We are developing a technique for measuring the EOS in a dense plasma, conditions far away from the standard Hugoniot. This technique requires that the initial condition of the material be at densities well below and temperatures well above standard. We have completed initial experiments producing and characterizing the plasma targets, a CH foam that has been heated to 1 eV using gold m-band x-rays created with the Trident laser. The measurements include visible spectroscopy and imaging along with x-ray radiography of this plasma target. Simulations of these initial measurements and of the laser drive necessary to produce a uniform shock in the material are also shown. The conditions that we calculate to be produced by this shock are then compared to models for the EOS of this material.

  5. Can attention be confined to just part of a moving object? Revisiting target-distractor merging in multiple object tracking.

    PubMed

    Howe, Piers D; Incledon, Natalie C; Little, Daniel R

    2012-01-01

    While it was initially thought that attention was space-based, more recent work has shown that attention can also be object-based, in that observers find it easier to attend to different parts of the same object than to different parts of different objects. Such studies have shown that attention more easily spreads throughout an object than between objects. However, it is not known to what extent attention can be confined to just part of an object and to what extent attending to part of an object necessarily causes the entire object to be attended. We have investigated this question in the context of the multiple object tracking paradigm in which subjects are shown a scene containing a number of identical moving objects and asked to mentally track a subset of them, the targets, while not tracking the remainder, the distractors. Previous work has shown that joining each target to a distractor by a solid connector so that each target-distractor pair forms a single physical object, a technique known as target-distractor merging, makes it hard to track the targets, suggesting that attention cannot be restricted to just parts of objects. However, in that study the target-distractor pairs continuously changed length, which in itself would have made tracking difficult. Here we show that it remains difficult to track the targets even when the target-distractor pairs do not change length and even when the targets can be differentiated from the connectors that join them to the distractors. Our experiments suggest that it is hard to confine attention to just parts of objects, at least in the case of moving objects.

  6. Inertial confinement fusion target component fabrication and technology development support: Annual report, October 1, 1995--September 30, 1996

    SciTech Connect

    Hoppe, M.

    1997-02-01

    On December 30, 1990, the U.S. Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion (ICF) Target Component Fabrication and Technology Development Support contractor. In September 1995 this contract ended and a second contract was issued for us to continue this ICF target support work. This report documents the technical activities of the period October 1, 1995 through September 30, 1996. During this period, GA and our partners WJ Schafer Associates (WJSA) and Soane Technologies, Inc. (STI) were assigned 14 formal tasks in support of the Inertial Confinement Fusion program and its five laboratories. A portion of the effort on these tasks included providing direct {open_quotes}Onsite Support{close_quotes} at Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratory Albuquerque (SNLA). We fabricated and delivered over 800 gold-plated hohlraum mandrels to LLNL, LANL and SNLA. We produced nearly 1,200 glass and plastic target capsules for LLNL, LANL, SNLA and University of Rochester/Laboratory for Laser Energetics (UR/LLE). We also delivered over 100 flat foil targets for Naval Research Lab (NRL) and SNLA in FY96. This report describes these target fabrication activities and the target fabrication and characterization development activities that made the deliveries possible. The ICF program is anticipating experiments at the OMEGA laser and the National Ignition Facility (NIF) which will require capsules containing cryogenic layered D{sub 2} or deuterium-tritium (DT) fuel. We are part of the National Cryogenic Target Program to create and demonstrate viable ways to generate and characterize cryogenic layers. Substantial progress has been made on ways to both create and characterize viable layers. During FY96, significant progress was made in the design of the OMEGA Cryogenic Target System that will field cryogenic targets on OMEGA.

  7. Can Attention Be Confined to Just Part of a Moving Object? Revisiting Target-Distractor Merging in Multiple Object Tracking

    PubMed Central

    Howe, Piers D.; Incledon, Natalie C.; Little, Daniel R.

    2012-01-01

    While it was initially thought that attention was space-based, more recent work has shown that attention can also be object-based, in that observers find it easier to attend to different parts of the same object than to different parts of different objects. Such studies have shown that attention more easily spreads throughout an object than between objects. However, it is not known to what extent attention can be confined to just part of an object and to what extent attending to part of an object necessarily causes the entire object to be attended. We have investigated this question in the context of the multiple object tracking paradigm in which subjects are shown a scene containing a number of identical moving objects and asked to mentally track a subset of them, the targets, while not tracking the remainder, the distractors. Previous work has shown that joining each target to a distractor by a solid connector so that each target-distractor pair forms a single physical object, a technique known as target-distractor merging, makes it hard to track the targets, suggesting that attention cannot be restricted to just parts of objects. However, in that study the target-distractor pairs continuously changed length, which in itself would have made tracking difficult. Here we show that it remains difficult to track the targets even when the target-distractor pairs do not change length and even when the targets can be differentiated from the connectors that join them to the distractors. Our experiments suggest that it is hard to confine attention to just parts of objects, at least in the case of moving objects. PMID:22859990

  8. Self-organized criticality and the dynamics of near-marginal turbulent transport in magnetically confined fusion plasmas

    NASA Astrophysics Data System (ADS)

    Sanchez, R.; Newman, D. E.

    2015-12-01

    The high plasma temperatures expected at reactor conditions in magnetic confinement fusion toroidal devices suggest that near-marginal operation could be a reality in future devices and reactors. By near-marginal it is meant that the plasma profiles might wander around the local critical thresholds for the onset of instabilities. Self-organized criticality (SOC) was suggested in the mid 1990s as a more proper paradigm to describe the dynamics of tokamak plasma transport in near-marginal conditions. It advocated that, near marginality, the evolution of mean profiles and fluctuations should be considered simultaneously, in contrast to the more common view of a large separation of scales existing between them. Otherwise, intrinsic features of near-marginal transport would be missed, that are of importance to understand the properties of energy confinement. In the intervening 20 years, the relevance of the idea of SOC for near-marginal transport in fusion plasmas has transitioned from an initial excessive hype to the much more realistic standing of today, which we will attempt to examine critically in this review paper. First, the main theoretical ideas behind SOC will be described. Secondly, how they might relate to the dynamics of near-marginal transport in real magnetically confined plasmas will be discussed. Next, we will review what has been learnt about SOC from various numerical studies and what it has meant for the way in which we do numerical simulation of fusion plasmas today. Then, we will discuss the experimental evidence available from the several experiments that have looked for SOC dynamics in fusion plasmas. Finally, we will conclude by identifying the various problems that still remain open to investigation in this area. Special attention will be given to the discussion of frequent misconceptions and ongoing controversies. The review also contains a description of ongoing efforts that seek effective transport models better suited than traditional

  9. Saturation of the Two-Plasmon Decay Instability in Long-Scale-Length Plasmas Relevant to Direct-Drive Inertial Confinement Fusion

    SciTech Connect

    Froula, D. H.; Yaakobi, B.; Hu, S. X.; Chang, P-Y.; Craxton, R. S.; Edgell, D. H.; Follett, R.; Michel, D. T.; Myatt, J. F.; Seka, W.; Short, R. W.; Solodov, A.; Stoeckl, C.

    2012-04-01

    Measurements of the hot-electron generation by the two-plasmon-decay instability are made in plasmas relevant to direct-drive inertial confinement fusion. Density-scale lengths of 400 {micro}m at n{sub cr}/4 in planar CH targets allowed the two-plasmon-decay instability to be driven to saturation for vacuum intensities above ~3.5 x 10{sup 14} W cm{sup -2}. In the saturated regime, ~1% of the laser energy is converted to hot electrons. The hot-electron temperature is measured to increase rapidly from 25 to 90 keV as the laser beam intensity is increased from 2 to 7 x 10{sup 14} W cm{sup -2}. This increase in the hot-electron temperature is compared with predictions from nonlinear Zakharov models.

  10. High energy and density plasmas produced by UHI interaction and buried-layer targets

    NASA Astrophysics Data System (ADS)

    Baton, Sophie; Dervieux, Vincent; Loupias, Berenice; Blancard, Christophe; Bowen, Christopher; Gremillet, Laurent; Lecherbourg, Ludovic; Pain, Jean-Christophe; Reverdin, Charles; Renaudin, Patrick; Rousseaux, Christophe; Silvert, Virginie; Allan, Peter; Brown, Colin; Hill, Matthew; Hoarty, David

    2013-10-01

    The radiative properties of hot (hundreds of eV), dense (rho ~ rhosol) plasmas are of interest in several research fields including inertial confinement fusion and astrophysics. The achieved plasma conditions (temperature, density, LTE/NLTE) have to be well characterized to constrain equation of state and opacity models. Ongoing progresses in ultra-intense laser facilities have led to the experimental demonstration of laser-driven isochoric heating of solid-density, micrometer targets to high temperatures (>100 eV). Here, we report on a recent experiment carried out with the ELFIE at LULI. The ultra-fast heating of various targets (multi-layered and reduced-mass targets) by using different laser conditions (1w and 2w) was inferred from their thermal x-ray emission. Two main diagnostics were used: a time-integrated Von Hamos crystal spectrometer and a toroidal crystal spectrometer coupled to an x-ray streak camera. According to combined atomic physics and hydrodynamic calculations, the measurements are consistent with densities rho ~ rhosol and maximum temperatures T ~ 450 eV.

  11. Inertial Confinement Fusion Target Component Fabrication and Technology Development Support. Annual report, January 1, 1991--September 30, 1992

    SciTech Connect

    Steinman, D.

    1993-03-01

    On December 31, 1990, the US Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion (ICF) Target Component Fabrication and Technology Development Support contractor. This report documents the technical activities of the period January 1, 1991 through September 30, 1992. During this period, GA was assigned 15 tasks in support of the Inertial Confinement Fusion program and its laboratories. These tasks included Facilities Activation, Staff Development, and Capabilities Validation to establish facilities and equipment, and demonstrate capability to perform ICF target fabrication research, development and production activities. The capabilities developed and demonstrated are those needed for fabrication and precise characterization of polymer shells and polymer coatings. We made progress toward production capability for glass shells, barrier layer coatings, and gas idling of shells. We fabricated over 1000 beam diagnostic foil targets for Sandia National Laboratory Albuquerque and provided full-time on-site engineering support for target fabrication and characterization. We initiated development of methods to fabricate polymer shells by a controlled mass microencapsulation technique, and performed chemical syntheses of several chlorine- and silicon-doped polymer materials for the University of Rochester`s Laboratory for Laser Energetics (UR/LLE). We performed the conceptual design of a cryogenic target handling system for UR/LLE that will fill, transport, layer, and characterize targets filled with cryogenic deuterium or deuterium-tritium fuel, and insert these cryogenic targets into the OMEGA-Upgrade target chamber for laser implosion experiments. This report summarizes and documents the technical progress made on these tasks.

  12. E-H mode transition of a high-power inductively coupled plasma torch at atmospheric pressure with a metallic confinement tube

    NASA Astrophysics Data System (ADS)

    Altenberend, Jochen; Chichignoud, Guy; Delannoy, Yves

    2012-08-01

    Inductively coupled plasma torches need high ignition voltages for the E-H mode transition and are therefore difficult to operate. In order to reduce the ignition voltage of an RF plasma torch with a metallic confinement tube the E-H mode transition was studied. A Tesla coil was used to create a spark discharge and the E-H mode transition of the plasma was then filmed using a high-speed camera. The electrical potential of the metallic confinement tube was measured using a high-voltage probe. It was found that an arc between the grounded injector and the metallic confinement tube is maintained by the electric field (E-mode). The transition to H-mode occurred at high magnetic fields when the arc formed a loop. The ignition voltage could be reduced by connecting the metallic confinement tube with a capacitor to the RF generator.

  13. Spectral diagnostics of laser erosion plasma of mercury chalcogenide targets

    NASA Astrophysics Data System (ADS)

    Kotlyarchuk, B. K.; Popovych, D. I.; Savchuk, V. K.; Savitsky, V. G.

    1995-11-01

    The article sets out to investigate spatial-time and spectral characteristics of laser erosive vapor-plasma torch (EVT), formed at the vaporization of mercury chalcogenines targets. Its influence on the synthesis processes of HgTe and CdHgTe layers, condensed in mercury vapor, is described. It is shown that the laser radiation flux density and Hg vapor pressure in the reaction chamber are dominating factors which determine the character of gas-dynamic spread and EVT composition of mercury chalcogenides targets.

  14. Observation of High-Field-Side Crash and Heat Transfer during Sawtooth Oscillation in Magnetically Confined Plasmas

    SciTech Connect

    Park, H.K.; Mazzucato, E.; Luhmann, N.C. Jr.; Domier, C.W.; Xia, Z.; Donne, A.J.H.; Classen, I.G.J.; Pol, M.J. van de; Munsat, T.

    2006-05-19

    High resolution (temporal and spatial), two-dimensional images of electron temperature fluctuations during sawtooth oscillations were employed to study the crash process and heat transfer in magnetically confined toroidal plasmas. The combination of kink and local pressure driven instabilities leads to a small poloidally localized puncture in the magnetic surface at both the low and the high field sides of the poloidal plane. This observation closely resembles the 'fingering event' of the ballooning mode model with the high-m mode only predicted at the low field side.

  15. Quasi-analytical method for solving nonlinear differential equations for turbulent self-confined magneto-plasmas

    NASA Astrophysics Data System (ADS)

    Maurier, M.; Hayd, A.; Kaeppeler, H. J.

    1986-09-01

    The mathematical procedures employed in REDUCE/FORTRAN, a hybrid code developed by Hearn (1969 and 1973) and Hayd and Meinke (1980) to compute the dynamics of confined plasmas with simple magnetic-field configurations (Hayd et al., 1982; Kaeppeler, 1982; Kaeppeler et al., 1983) are explained. In REDUCE/FORTRAN, the dispersion relation is derived analytically, Fourier-transformed, and solved numerically, and the solution is then fitted to an analytical formula for further manipulation (including back-transformation). The procedure is demonstrated by solving the Burgers equation with a delta function for the initial conditions, and numerical results are presented in tables and graphs.

  16. Exact solutions of the Grad-Shafranov equation via similarity reduction and applications to magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Kaltsas, Dimitrios A.; Throumoulopoulos, George N.

    2016-10-01

    We derive exact solutions of a linear form of the Grad-Shafranov (GS) equation, including incompressible equilibrium flow, using ansatz-based similarity reduction methods. The linearity of the equilibrium equation allows linear combinations of solutions in order to obtain axisymmetric MHD equilibria with closed and nested magnetic surfaces which are favorable for the effective confinement of laboratory plasmas. In addition, employing the same reduction methods we obtain analytical solutions for several non-linear forms of the GS equation. In this context analytic force-free solutions in both linear and nonlinear regimes are also derived.

  17. High-{beta}, improved confinement reversed-field pinch plasmas at high density

    SciTech Connect

    Wyman, M. D.; Chapman, B. E.; Ahn, J. W.; Almagri, A. F.; Anderson, J. K.; Den Hartog, D. J.; Ebrahimi, F.; Ennis, D. A.; Fiksel, G.; Gangadhara, S.; Goetz, J. A.; O'Connell, R.; Oliva, S. P.; Prager, S. C.; Reusch, J. A.; Sarff, J. S.; Stephens, H. D.; Bonomo, F.; Franz, P.; Brower, D. L.

    2008-01-15

    In Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] discharges where improved confinement is brought about by modification of the current profile, pellet injection has quadrupled the density, reaching n{sub e}=4x10{sup 19} m{sup -3}. Without pellet injection, the achievable density in improved confinement discharges had been limited by edge-resonant tearing instability. With pellet injection, the total beta has been increased to 26%, and the energy confinement time is comparable to that at low density. Pressure-driven local interchange and global tearing are predicted to be linearly unstable. Interchange has not yet been observed experimentally, but there is possible evidence of pressure-driven tearing, an instability usually driven by the current gradient in the reversed-field pinch.

  18. Plasma properties of RF magnetron sputtering system using Zn target

    SciTech Connect

    Nafarizal, N.; Andreas Albert, A. R.; Sharifah Amirah, A. S.; Salwa, O.; Riyaz Ahmad, M. A.

    2012-06-29

    In the present work, we investigate the fundamental properties of magnetron sputtering plasma using Zn target and its deposited Zn thin film. The magnetron sputtering plasma was produced using radio frequency (RF) power supply and Argon (Ar) as ambient gas. A Langmuir probe was used to collect the current from the plasma and from the current intensity, we calculate the electron density and electron temperature. The properties of Zn sputtering plasma at various discharge conditions were studied. At the RF power ranging from 20 to 100 W and gas pressure 5 mTorr, we found that the electron temperature was almost unchanged between 2-2.5 eV. On the other hand, the electron temperature increased drastically from 6 Multiplication-Sign 10{sup 9} to 1 Multiplication-Sign 10{sup 10}cm{sup -3} when the discharge gas pressure increased from 5 to 10 mTorr. The electron microscope images show that the grain size of Zn thin film increase when the discharge power is increased. This may be due to the enhancement of plasma density and sputtered Zn density.

  19. Characterization of Dense Plasma Targets for Equation of State Experiments.

    NASA Astrophysics Data System (ADS)

    Hurry, Tom; Benage, John; Cobble, Jim; Dodd, Evan; Herrmann, Hans; Ortiz, Tom; Workman, Jonathan

    2006-10-01

    The measurement of the Equation of State (EOS) of materials in the dense-plasma state is difficult. The standard method for measuring EOS relies on the shock driven Hugoniot technique, where the material is initially at standard temperature and pressure and is shocked using a flyer plate. The locus of states produced using this technique is called the standard Hugoniot. However, the states produced do not fall into the regime of dense plasmas, where the EOS of the material is quite uncertain. We are developing a technique for measuring the EOS in a dense plasma, conditions far away from the standard Hugoniot. This technique requires that the initial condition of the material be at densities well below and temperatures well above standard. We have completed initial experiments producing and characterizing the plasma targets using visible spectroscopy and imaging. We have also begun development of a dynamic phase contrast imaging system required for measuring the shock velocity in the plasma. Simulations of these initial measurements and of the laser drive necessary to produce a uniform shock in the material are also shown. The conditions that we calculate to be produced by this shock are then compared to models for the EOS of this material.

  20. Studies of thermal energy confinement scaling in PDX plasmas: D/sup 0/. -->. H/sup +/ limiter discharges

    SciTech Connect

    Kaye, S.M.; Goldston, R.J.; Bell, M.; Bol, K.; Bitter, M.; Fonck, R.; Grek, B.; Hawryluk, R.J.; Johnson, D.; Kaita, R.

    1984-06-01

    Experiments were performed on the PDX tokamak to study plasma heating and ..beta.. scaling with higher power, near-perpendicular neutral beam injection. The data taken during these experiments were analyzed using a time-dependent data interpretation code (TRANSP) to study the transport and thermal confinement scaling over a wide range of plasma parameters. This study focuses on results from experiments with D/sup 0/ injection into H/sup +/ plasmas using graphite rail limiters, a = 40 to 44 cm, R = 143 cm, I/sub p/ = 200 to 480 kA, B/sub T/ = 0.7 to 2.2 T, and typically anti n/sub e/ = 2.5 to 4.2 x 10/sup 13/ cm/sup -3/. The results of this study indicate that for both ohmic and neutral beam heated discharges the energy flow out of the plasma is dominated by anomalous electron losses, attributed to electron thermal conduction. The ion conduction losses are well described to electron thermal conduction. The ion conduction losses are well described by neoclassical theory; however, the total ion loss influences the power balance significantly only at high toroidal fields and high plasma currents.

  1. Inertial confinement fusion target component fabrication and technology development support: Annual report, October 1, 1993--September 30, 1994

    SciTech Connect

    Hoppe, M.

    1995-04-01

    On December 30, 1990, the US Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion (ICF) Target Component Fabrication and Technology Development Support contractor. During the period, GA was assigned 17 tasks in support of the Inertial Confinement Fusion program and its laboratories. This year they achieved full production capabilities for the micromachining, dimensional characterization and gold plating of hohlraums. They fabricated and delivered 726 gold-plated mandrels of 27 different types to LLNL and 48 gold-plated mandrels of two different types to LANL. They achieved full production capabilities in composite capsule production ad delivered in excess of 240 composite capsules. They continuously work to improve performance and capabilities. They were also directed to dismantle, remove, and disposition all equipment at the previous contractor (KMSF) that had radioactive contamination levels low enough that they could be exposed to the general public without radiological constraints. GA was also directed to receive and store the tritium fill equipment. They assisted LANL in the development of techniques for characterization of opaque targets. They developed deuterated and UV-opaque polymers for use by the University of Rochester`s Laboratory for Laser Energetics (UR/LLE) and devised a triple-orifice droplet generator to demonstrate the controlled-mass nature of the microencapsulation process. The ICF program is anticipating experiments at NIF and the Omega Upgrade. Both facilities will require capsules containing layered D{sub 2} or D-T fuel. They continued engineering and assembly of equipment for a cryogenic target handling system for UR/LLE that will fill, transport, layer, and characterize targets filled with cryogenic deuterium or deuterium-tritium fuel, and insert these cryogenic targets into the OMEGA Upgrade target chamber for laser implosion experiments.

  2. Study on the effect of target on plasma parameters of magnetron sputtering discharge plasma

    SciTech Connect

    Saikia, P.; Kakati, B.; Saikia, B. K.

    2013-10-15

    In this study, the effect of magnetron target on different plasma parameters of Argon/Hydrogen (Ar - H{sub 2}) direct current (DC) magnetron discharge is examined. Here, Copper (Cu) and Chromium (Cr) are used as magnetron targets. The value of plasma parameters such as electron temperature (kT{sub e}), electron density (N{sub e}), ion density (N{sub i}), degree of ionization of Ar, and degree of dissociation of H{sub 2} for both the target are studied as a function of input power and hydrogen content in the discharge. The plasma parameters are determined by using Langmuir probe and Optical emission spectroscopy. On the basis of the different reactions in the gas phase, the variation of plasma parameters and sputtering rate are explained. The obtained results show that electron and ion density decline with gradual addition of Hydrogen in the discharge and increase with rising input power. It brings significant changes on the degree of ionization of Ar and dissociation of H{sub 2}. The enhanced value of electron density (N{sub e}), ion density (N{sub i}), degree of Ionization of Ar, and degree of dissociation of H{sub 2} for Cr compared to Cu target is explained on the basis of it's higher Ion Induced Secondary Electron Emission Coefficient (ISEE) value.

  3. Non-Neutral Plasma Confinement In A Cusp-Trap And Possible Application To Anti-Hydrogen Beam Generation

    SciTech Connect

    Mohri, Akihiro; Kanai, Yasuyuki; Nakai, Yoichi; Yamazaki, Yasunori

    2005-10-19

    A new scheme for synthesizing antihydrogen by trapping positrons and antiprotons in a field consisting of a magnetic quadrupole and an electric octupole (cusp -trap) is now under investigation. The total electric field of the octupole with the space charge of a nonneutral plasma composed of particles of the same sign of charge, i.e., positrons or mixture of electrons and antiprotons, is expected to form a potential well for particles of the opposite sign of charge. Particles trapped in the well are mixed with the present dense particles, where positrons and antiprotons will combine to produce antihydrogen atoms. A considerable fraction of antihydrogen atoms in low-field seeking states will be transported outside as a beam.Experiments on electron confinement in the cusp-trap were carried out in a strong magnetic quadrupole (3.8T at the maximum on the axis). The confinement time reached 400s for the trapped electron number N0= 3.6x107. The time decreased with N0 but it was still about 100s for N0= 1.6x108.An electron plasma initially formed around the zero-field point rapidly expanded and settled down onto a quasi-stable state. Cross-sectional density profiles had shapes like a high volcano with a big crater. Analysis of the density profile shows that a potential well for oppositely charged particles (positive ions in this case) is probably formed inside the trapped electrons.

  4. Inertial confinement fusion target component fabrication and technology development support: Annual report, October 1, 1997--September 30, 1998

    SciTech Connect

    Gibson, J.

    1998-12-01

    During this period, General Atomics (GA) and their partner Schafer Corporation were assigned 17 formal tasks in support of the Inertial Confinement Fusion (ICF) program and its five laboratories. A portion of the effort on these tasks included providing direct ``On-site Support`` at Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratory Albuquerque (SNLA). They fabricated and delivered over 1,200 hohlraum mandrels and numerous other micromachined components to LLNL, LANL, and SNLA. They produced more than 1,300 glass and plastic target capsules for LLNL, LANL, SNLA, and the University of Rochester/Laboratory for Laser Energetics (UR/LLE). They also delivered nearly 2,000 various target foils and films for Naval Research Lab (NRL) and UR/LLE in FY98. This report describes these target fabrication activities and the target fabrication and characterization development activities that made the deliveries possible. During FY98, great progress was made by the GA/Schafer-UR/LLE-LANL team in the design, procurement, installation, and testing of the OMEGA Cryogenic Target System (OCTS) that will field cryogenic targets on OMEGA. The design phase was concluded for all components of the OCTS and all major components were procured and nearly all were fabricated. Many of the components were assembled and tested, and some have been shipped to UR/LLE. The ICF program is anticipating experiments at the OMEGA laser and the National Ignition Facility (NIF) which will require targets containing cryogenic layered D{sub 2} or deuterium-tritium (DT) fuel. They are part of the National Cryogenic Target Program and support experiments at LLNL and LANL to generate and characterize cryogenic layers for these targets. They also contributed cryogenic support and developed concepts for NIF cryogenic targets. This report summarizes and documents the technical progress made on these tasks.

  5. Inertial Confinement Fusion Target Component Fabrication and Technology Development report. Annual report, October 1, 1992--September 30, 1993

    SciTech Connect

    Steinman, D.

    1994-03-01

    On December 30, 1990, the US Department of Energy entered into a contract with General Atomics (GA) to be the Inertial Confinement Fusion Target Component Fabrication and Technology Development Support contractor. This report documents the technical activities which took place under this contract during the period of October 1, 1992 through September 30, 1993. During this period, GA was assigned 18 tasks in support of the Inertial Confinement Fusion program and its laboratories. These tasks included ``Capabilities Activation`` and ``Capabilities Demonstration`` to enable us to begin production of glass and composite polymer capsules. Capsule delivery tasks included ``Small Glass Shell Deliveries`` and ``Composite Polymer Capsules`` for Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL). We also were asked to provide direct ``Onsite Support`` at LLNL and LANL. We continued planning for the transfer of ``Micromachining Equipment from Rocky Flats`` and established ``Target Component Micromachining and Electroplating Facilities`` at GA. We fabricated over 1100 films and filters of 11 types for Sandia National Laboratory and provided full-time onsite engineering support for target fabrication and characterization. We initiated development of methods to make targets for the Naval Research Laboratory. We investigated spherical interferometry, built an automated capsule sorter, and developed an apparatus for calorimetric measurement of fuel fill for LLNL. We assisted LANL in the ``Characterization of Opaque b-Layered Targets.`` We developed deuterated and UV-opaque polymers for use by the University of Rochester`s Laboratory for Laser Energetics (UR/LLE) and devised a triple-orifice droplet generator to demonstrate the controlled-mass nature of the microencapsulation process.

  6. Stability of liquid-nitrogen-jet laser-plasma targets

    SciTech Connect

    Fogelqvist, E. Kördel, M.; Selin, M.; Hertz, H. M.

    2015-11-07

    Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.

  7. Son of IXION: A Steady State Centrifugally Confined Plasma for Fusion*

    NASA Astrophysics Data System (ADS)

    Hassam, Adil

    1996-11-01

    A magnetic confinement scheme in which the inertial, u.grad(u), forces effect parallel confinement is proposed. The basic geometry is mirror-like as far as the poloidal field goes or, more simply, multipole (FM-1) type. The rotation is toroidal in this geometry. A supersonic rotation can effect complete parallel confinement, with the usual magnetic mirror force rendered irrelevant. The rotation shear, in addition, aids in the suppression of the flute mode. This suppression is not complete which indicates the addition of a toroidal field, at maximum of the order of the poloidal field. We show that at rotation in excess of Mach 3, the parallel particle and heat losses can be minimized to below the Lawson breakeven point. The crossfield transport can be expected to be better than tokamaks on account of the large velocity shear. Other advantages of the scheme are that it is steady state and disruption free. An exploratory experiment that tests equilibrium, parallel detachment, and MHD stability is proposed. The concept resembles earlier (Geneva, 1958) experiments on "homopolar generators" and a mirror configuration called IXION. Ixion, Greek mythological king, was forever strapped to a rotating, flaming wheel. *Work supported by DOE

  8. Infrared laser induced plasma diagnostics of silver target

    SciTech Connect

    Ahmat, L. Nadeem, Ali; Ahmed, I.

    2014-09-15

    In the present work, the optical emission spectra of silver (Ag) plasma have been recorded and analyzed using the laser induced breakdown spectroscopy technique. The emission line intensities and plasma parameters were investigated as a function of lens to sample distance, laser irradiance, and distance from the target surface. The electron number density (n{sub e}) and electron temperature (T{sub e}) were determined using the Stark broadened line profile and Boltzmann plot method, respectively. A gradual increase in the spectral line intensities and the plasma parameters, n{sub e} from 2.89 × 10{sup 17} to 3.92 × 10{sup 17 }cm{sup −3} and T{sub e} from 4662 to 8967 K, was observed as the laser irradiance was increased 2.29 × 10{sup 10}–1.06 × 10{sup 11} W cm{sup −2}. The spatial variations in n{sub e} and T{sub e} were investigated from 0 to 5.25 mm from the target surface, yielding the electron number density from 4.78 × 10{sup 17} to 1.72 × 10{sup 17 }cm{sup −3} and electron temperature as 9869–3789 K. In addition, the emission intensities and the plasma parameters of silver were investigated by varying the ambient pressure from 0.36 to 1000 mbars.

  9. Experimental study of the effects of lithium coated plasma facing components on energy confinement time in the CDX-U device

    NASA Astrophysics Data System (ADS)

    Spaleta, Jeffrey Dario

    Experimentally constrained equilibrium reconstructions are an important analysis tool used to understand the physics of magnetically confined plasmas. This thesis describes the first ever calculations of equilibrium reconstructions for spherical tokamak plasmas in the presence of lithium coated plasma facing components (PFC's) in the Current Drive eXperiment - Upgrade (CDX-U) device. Equilibria were calculated using a modified version of the Equilibrium and Stability Code (ESC), and were constrained by measurements made from a collection of magnetic field diagnostics. The ESC was modified to incorporate the first ever implementation of a novel response function technique for magnetic field diagnostic calibration. The technique is well suited for situations where the assumption of toroidal symmetry of the magnetic field is invalid, or when wall eddy currents are too large to neglect. Also included is a detailed discussion of the calculation of energy confinement time from power balance arguments, using parameters obtained from equilibrium reconstructions. The energy confinement time, as derived from plasma equilibria, was as large as 6 milliseconds for plasmas in the presence of both solid and liquid lithium PFC's. This represents a significant improvement over baseline plasmas, which typically had energy confinement times of 1 millisecond or less. The energy confinement for plasmas with lithium PFC's also showed an improvement over that expected from the ITER98y1 confinement scaling, which is derived from a database of earlier tokamak results. The improvement in confinement over this scaling correlates with the observed increase in density "pump-out", which is indicative of low wall-recycling. Traditionally, plasma fueling has been dominated by wall-recycling, with 90% or more of the fuel coming from recycling sources instead of externally controlled means, such as gas puffing or pellet injection. Previous lithium wall coating experiments on the Tokamak Fusion Test

  10. Excitation of Ion Acoustic Waves in Confined Plasmas with Untrapped Electrons

    NASA Astrophysics Data System (ADS)

    Schamis, Hanna; Dow, Ansel; Carlsson, Johan; Kaganovich, Igor; Khrabrov, Alexander

    2015-11-01

    Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand the electron kinetics in plasmas with strong emission, we have performed simulations using a reduced model with the LSP particle-in-cell code. This model aims to show the instability generated by the electron emission, in the form of ion acoustic waves near the sheath. It also aims to show the instability produced by untrapped electrons that propagate across the plasma, similarly to a beam, and can drive ion acoustic waves in the plasma bulk. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466.

  11. Converging geometry Rayleigh Taylor instability and central ignition of inertial confinement fusion targets

    NASA Astrophysics Data System (ADS)

    Atzeni, Stefano; Schiavi, Angelo; Temporal, Mauro

    2004-12-01

    The Rayleigh Taylor instability (RTI) of the inner surface of an inertial confinement fusion shell is studied through high-resolution two-dimensional numerical simulations. The instability is seeded by a mass displacement introduced in the simulations at the end of the implosion coasting stage. Analysis of single-mode, small-amplitude perturbations confirms that ablation caused by electron conduction and fusion alpha-particles causes significant growth reduction of all modes and stabilization of high-l modes. Different measures of the instability are discussed and compared with modified Takabe-like expressions. Large-amplitude multi-mode simulations are performed to study the effects of RTI on ignition and burn. RTI perturbations reduce the size of the central hot spot and delay ignition. For a few different perturbation spectra the dependence of fusion yield on the initial perturbation root mean square amplitude is studied.

  12. Development of aerogel-lined targets for inertial confinement fusion experiments

    SciTech Connect

    Braun, Tom

    2013-03-28

    This thesis explores the formation of ICF compatible foam layers inside of an ablator shell used for inertial confinement fusion experiments at the National Ignition Facility. In particular, the capability of p- DCPD polymer aerogels to serve as a scaffold for the deuterium-tritium mix was analyzed. Four different factors were evaluated: the dependency of different factors such as thickness or composition of a precursor solution on the uniformity of the aerogel layer, how to bring the optimal composition inside of the ablator shell, the mechanical stability of ultra-low density p-DCPD aerogel bulk pieces during wetting and freezing with hydrogen, and the wetting behavior of thin polymer foam layers in HDC carbon ablator shells with liquid deuterium. The research for thesis was done at Lawrence Livermore National Laboratory in cooperation with the Technical University Munich.

  13. Equilibrium, stability, and estimate of plasma confinement in the L-5 compact torsatron

    SciTech Connect

    Mikhailov, M. I.; Shafranov, V. D.; Drevlyak, M.; Nuehrenberg, J.; Grebenshchikov, S. E.; Kuznetsov, A. B.; Shchepetov, S. V.

    2011-04-15

    Possible parameters of a plasma in a compact torsatron that is to be constructed at the Prokhorov Institute of General Physics, Russian Academy of Sciences (the L-5 project) are discussed. The properties of the original vacuum configuration created by the external coils are described. The equilibrium of a plasma with a free boundary and the stability of local MHD modes are investigated. The effective magnetic field ripples and the structural factor of the bootstrap current in the 1/{nu} regime are calculated, as well as collisionless losses of trapped {alpha}-particles. The dependence of these properties on the relative plasma pressure is examined. It is shown that the maximum possible <{beta}> (the ratio of the gas-kinetic plasma pressure to the magnetic field pressure, averaged over the volume of the plasma column) consistent with equilibrium exceeds 2.0%. The power of the external sources for plasma heating in the anticipated operating modes is estimated using the present-day scalings. The efficiency of different methods for calculating the magnetic fields and, accordingly, the magnetic surfaces created by the external coils is analyzed in the Appendix.

  14. Ultrasmooth plasma polymerized coatings for laser-fusion targets

    SciTech Connect

    Letts, S.A.; Myers, D.W.; Witt, L.A.

    1980-08-26

    Coatings for laser fusion targets were deposited up to 135 ..mu..m thick by plasma polymerization onto 140 ..mu..m diameter DT filled glass microspheres. Ultrasmooth surfaces (no defect higher than 0.1 ..mu..m) were achieved by eliminating particulate contamination. Process generated particles were eliminated by determining the optimum operating conditions of power, gas flow, and pressure, and maintaining these conditions through feedback control. From a study of coating defects grown over known surface irregularities, a quantitative relationship between irregularity size, film thickness, and defect size was determined. This relationship was used to set standards for the maximum microshell surface irregularity tolerable in the production of hydrocarbon or fluorocarbon coated laser fusion targets.

  15. Extreme ultraviolet emission and confinement of tin plasmas in the presence of a magnetic field

    SciTech Connect

    Roy, Amitava E-mail: aroy@barc.gov.in; Murtaza Hassan, Syed; Harilal, Sivanandan S.; Hassanein, Ahmed; Endo, Akira; Mocek, Tomas

    2014-05-15

    We investigated the role of a guiding magnetic field on extreme ultraviolet (EUV) and ion emission from a laser produced Sn plasma for various laser pulse duration and intensity. For producing plasmas, planar slabs of pure Sn were irradiated with 1064 nm, Nd:YAG laser pulses with varying pulse duration (5–15 ns) and intensity. A magnetic trap was fabricated with the use of two neodymium permanent magnets which provided a magnetic field strength ∼0.5 T along the plume expansion direction. Our results indicate that the EUV conversion efficiency do not depend significantly on applied axial magnetic field. Faraday Cup ion analysis of Sn plasma show that the ion flux reduces by a factor of ∼5 with the application of an axial magnetic field. It was found that the plasma plume expand in the lateral direction with peak velocity measured to be ∼1.2 cm/μs and reduced to ∼0.75 cm/μs with the application of an axial magnetic field. The plume expansion features recorded using fast photography in the presence and absence of 0.5 T axial magnetic field are simulated using particle-in-cell code. Our simulation results qualitatively predict the plasma behavior.

  16. Effects of Lithium Plasma-Facing Surfaces on Particle Confinement in CDX-U

    NASA Astrophysics Data System (ADS)

    Gray, T.; Soukhanovskii, V.; Maingi, R.

    2005-10-01

    Recent experiments on the CDX-U spherical torus have successfully achieved a significant reduction in recycling with large-area liquid lithium plasma-facing surfaces. The effects of a liquid lithium toroidal limiter and evaporative lithium coatings on overall density and τp^* will be presented. Such conditions have also demonstrated the need to improve plasma fueling. To address this challenge, a supersonic gas injector, based on a Mach 8 Laval nozzle design,[1] has been installed on CDX-U. The fueling efficiency of the nozzle compared to standard gas puffing will be compared. [1] M. Baumgartner, Ph. D. thesis, Princeton University (1997)

  17. Effect of different tritium fractions on some plasma parameters in deuterium-tritium magnetic confinement fusion

    NASA Astrophysics Data System (ADS)

    Motevalli, S. M.; Mohsenpour, T.; Dashtban, N.

    2016-09-01

    Nearly all reactor projects have considered deuterium-tritium (D-T) fusion. The cross section of D-T reaction is larger than those of other fusion reactions, thus it is considered to be a more favorable reaction. The mix of fuel can vary. In this work, a comparison between the effects of different mixture of D-T fuel on the plasma parameters is made. A time dependence calculation of the fusion process is performed using the zero-dimensional model based on a coupled set of particle and energy balance equations in ITER (International Thermonuclear Experimental Reactor). The time evolution of plasma parameters is also analyzed numerically.

  18. Steady-shear-enhanced microdiffusion with multiple time scales of confined, mesoscopic, two-dimensional dusty-plasma liquids.

    PubMed

    Io, Chong-Wai; I, Lin

    2009-09-01

    We experimentally investigate the multitime scale diffusion and the spatiotemporal behaviors of the degrees of enhancement for the longitudinal and the transverse diffusions in a confined mesoscopic quasi-two-dimensional dusty-plasma liquid sheared by two parallel counterpropagating laser beams. The steady external drive directly enhances the longitudinal cooperative hopping, associated with the shear bands that have high shear rate near boundaries. It drastically excites the slow hopping modes to high fluctuation level in the outer band region, accompanied by the enhanced superdiffusion. Through cascaded many-body interaction, the excitation flows from the outer region toward the center region, from the longitudinal modes to the transverse mode, and from the slow hopping modes to the fast caging modes, which are in better contact with the thermal bath. It causes the weaker enhancement of fluctuation level, and diffusion for the center region and the fast modes. The boundary confinement further breaks the system symmetry and enhances anisotropy. It has much stronger effect on the suppression of the transverse hopping modes than the longitudinal hopping mode. The degrees of enhancement of the fluctuations by the shear stress are highly anisotropic for the large amplitude slow modes, especially in the outer region but are more isotropic in the inner band.

  19. Magntohydrodynamic behavior of capacitor-coil target toward alternative inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Sasaki, T.; Oyama, S.; Sugimoto, Y.; Takahashi, K.; Kikuchi, T.; Harada, N.; Nagatomo, H.; Fujioka, S.; Sunahara, A.

    2016-05-01

    To understand its magnetohydrodynamic behaviors and the electrical properties, we proposed to evaluate both experimental observations and numerical simulations. Electrical conductivity for nickel in warm dense matter (WDM) state has been measured with an exploding wire in a quasi-isochoric vessel. The result shows that the electrical conductivity for nickel in WDM is relatively high from the comparison of the electrical conductivities for several materials in WDM state. However, the skin effect in the capacitor-coil target will be neglected from the estimation. A two-dimensional magnetohydrodynamic simulation for the capacitor-coil target has been demonstrated. The results shows that the distribution of B-field in the capacitor-coil target depends on the electrical conductivity model.

  20. Discovery of stationary operation of quiescent H-mode plasmas with net-zero neutral beam injection torque and high energy confinement on DIII-D

    NASA Astrophysics Data System (ADS)

    Burrell, K. H.; Barada, K.; Chen, X.; Garofalo, A. M.; Groebner, R. J.; Muscatello, C. M.; Osborne, T. H.; Petty, C. C.; Rhodes, T. L.; Snyder, P. B.; Solomon, W. M.; Yan, Z.; Zeng, L.

    2016-05-01

    Recent experiments in DIII-D [J. L. Luxon et al., in Plasma Physics and Controlled Nuclear Fusion Research 1996 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159] have led to the discovery of a means of modifying edge turbulence to achieve stationary, high confinement operation without Edge Localized Mode (ELM) instabilities and with no net external torque input. Eliminating the ELM-induced heat bursts and controlling plasma stability at low rotation represent two of the great challenges for fusion energy. By exploiting edge turbulence in a novel manner, we achieved excellent tokamak performance, well above the H98y2 international tokamak energy confinement scaling (H98y2 = 1.25), thus meeting an additional confinement challenge that is usually difficult at low torque. The new regime is triggered in double null plasmas by ramping the injected torque to zero and then maintaining it there. This lowers E × B rotation shear in the plasma edge, allowing low-k, broadband, electromagnetic turbulence to increase. In the H-mode edge, a narrow transport barrier usually grows until MHD instability (a peeling ballooning mode) leads to the ELM heat burst. However, the increased turbulence reduces the pressure gradient, allowing the development of a broader and thus higher transport barrier. A 60% increase in pedestal pressure and 40% increase in energy confinement result. An increase in the E × B shearing rate inside of the edge pedestal is a key factor in the confinement increase. Strong double-null plasma shaping raises the threshold for the ELM instability, allowing the plasma to reach a transport-limited state near but below the explosive ELM stability boundary. The resulting plasmas have burning-plasma-relevant βN = 1.6-1.8 and run without the need for extra torque from 3D magnetic fields. To date, stationary conditions have been produced for 2 s or 12 energy confinement times, limited only by external hardware constraints. Stationary operation with

  1. Energy gain of a thin DT shell target in inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Khoshbinfar, Soheil

    2014-11-01

    Estimation of maximum possible energy gain for a given energy of driver has always become a key point in inertial confinement fusion. It has direct impact on the cost of produced electricity. Here, we employ a hydrodynamics model to assess energy gain in the case of a symmetrical hydrodynamics implosion where a narrow fuel shell consisting of deuterium-tritium (DT), can experience an isentropic compression in a self-similar regime. Introducing a set of six state parameters {Hhs, Ths, Uimp, αc, ξhs and μhs}, the final fuel state close to ignition is fully described. It enables us to calculate energy gain curves for specific set of these state variables. The envelope of the energy gain family curves provide a limiting gain curve Gfuel fuel* ∝ Ef0.36. Next, we took into account the inertial of cold surrounding fuel on the ignition process. It changes the limiting gain curve slope to 0.41. Finally, the analytical model results assessed and validated using numerical simulation code.

  2. Process for manufacture of inertial confinement fusion targets and resulting product

    DOEpatents

    Masnari, Nino A.; Rensel, Walter B.; Robinson, Merrill G.; Solomon, David E.; Wise, Kensall D.; Wuttke, Gilbert H.

    1982-01-01

    An ICF target comprising a spherical pellet of fusion fuel surrounded by a concentric shell; and a process for manufacturing the same which includes the steps of forming hemispheric shells of a silicon or other substrate material, adhering the shell segments to each other with a fuel pellet contained concentrically therein, then separating the individual targets from the parent substrate. Formation of hemispheric cavities by deposition or coating of a mold substrate is also described. Coatings or membranes may also be applied to the interior of the hemispheric segments prior to joining.

  3. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    SciTech Connect

    Pisarczyk, T.; Kalinowska, Z.; Badziak, J.; Borodziuk, S.; Chodukowski, T.; Kasperczuk, A.; Parys, P.; Rosinski, M.; Gus'kov, S. Yu.; Demchenko, N. N.; Batani, D.; Antonelli, L.; Folpini, G.; Maheut, Y.; Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P.; Labate, L.; Krousky, E.; and others

    2014-01-15

    Efficiency of the laser radiation energy transport into the shock wave generated in layered planar targets (consisting of massive Cu over coated by thin CH layer) was investigated. The targets were irradiated using two laser pulses. The 1ω pulse with the energy of ∼50 J produced a pre-plasma, imitating the corona of the pre-compressed inertial confinement fusion target. The second main pulse used the 1ω or 3ω laser harmonics with the energy of ∼200 J. The influence of the pre-plasma on parameters of the shock wave was determined from the crater volume measurements and from the electron density distribution measured by 3-frame interferometry. The experimental results show that the energy transport by fast electrons provides a definite contribution to the dynamics of the ablative process, to the shock wave generation, and to the ablation pressure in dependence on the target irradiation conditions. The strong influence of the pre-plasma on the investigated process was observed in the 1ω case. Theoretical analysis supports the explanation of experimental results.

  4. Space-charge waves in magnetized and collisional quantum plasma columns confined in carbon nanotubes

    SciTech Connect

    Bagheri, Mehran; Abdikian, Alireza

    2014-04-15

    We study the dispersion relation of electrostatic waves propagating in a column of quantum magnetized collisional plasma embraced completely by a metallic single-walled carbon nanotubes. The analysis is based on the quantum linearized hydrodynamic formalism of collective excitations within the quasi-static approximation. It is shown when the electronic de Broglie's wavelength of the plasma is comparable in the order of magnitude to the radius of the nanotube, the quantum effects are quite meaningful and our model anticipates one acoustical and two optical space-charge waves which are positioned into three propagating bands. With increasing the nanotube radius, the features of the acoustical branch remain unchanged, yet two distinct optical branches are degenerated and the classical behavior is recovered. This study might provide a platform to create new finite transverse cross section quantum magnetized plasmas and to devise nanometer dusty plasmas based on the metallic carbon nanotubes in the absence of either a drift or a thermal electronic velocity and their existence could be experimentally examined.

  5. Design of a toroidal plasma confinement device with a levitated super-conducting internal coil

    SciTech Connect

    Ogawa, Y.; Morikawa, J.; Himura, H.; Kondoh, S.; Yoshida, Z.; Mito, T.; Yanagi, N.; Iwakuma, N.

    1999-12-10

    A toroidal device has been constructed and nonneutral plasma experiments have been intensively promoted, where an internal ring coil with a copper conductor has been employed. We are now designing a toroidal plasma trapping device with a levitated superconducting internal coil, so as to avoid plasma loss through current-lead and support structures of the internal coil. Typical machine parameters are as follows; the major radius of the internal ring coil is 40 cm and the coil current is 500 kA. Concerning to the levitated coil, the high-temperature (high-Tc) super-conducting coil is preferable for plasma experiments, because long pulse and/or high power heating experiments might be available due to the good property for the thermal stability and large heat capacity of the high-Tc super-conducting coil. Our primary candidate is Bi-2223 super-conducting cable. Since the maximum magnetic field strength is around 2 T in our device, the deterioration of the critical current is not so severe up to 40 K. We are now promoting a detailed design of the toroidal device with a high-Tc super-conducting internal coil.

  6. Design of a Toroidal Plasma Confinement Device with a Levitated Super-Conducting Internal Coil

    SciTech Connect

    Y. Ogawa; H. Himura; S. Kondoh; J. Morikawa; Z. Yoshida

    1999-12-31

    A toroidal device has been constructed and nonneutral plasma experiments have been intensively promoted, where an internal ring coil with a copper conductor has been employed. We are now designing a toroidal plasma trapping device with a levitated superconducting internal coil, so as to avoid plasma loss through current-lead and support structures of the internal coil. Typical machine parameters are as follows; the major radius of the internal ring coil is 40 cm and the coil current is 500 kA. Concerning to the levitated coil, the high-temperature (high-Tc) super-conducting coil is preferable for plasma experiments, because long pulse and/or high power heating experiments might be available due to the good property for the thermal stability and large heat capacity of the high-Tc super-conducting coil. Our primary candidate is Bi-2223 super-conducting cable. Since the maximum magnetic field strength is around 2 T in our device, the deterioration of the critical current is not so severe up to 40 K. We are now promoting a detailed design of the toroidal device with a high-Tc super-conducting internal coil.

  7. Perspectives of millimeter-wave collective Thomson scattering of confined alphas in ignited plasmas

    SciTech Connect

    Tartari, U.; Nowak, S.; Ramponi, G.

    1996-11-01

    Collective Thomson scattering on alpha density fluctuations in ignited plasma regimes is investigated with reference to a promising candidate source as the mm-wave gyrotron and a representative ITER-like plasma regime. It is shown that a number of intrinsic limitations characterize each of the equatorial scattering geometries selected as more promising, namely a backscattering geometry at {ital f}{sub 0}=80 GHz and two similar quasiorthogonal geometries at {ital f}{sub 0}=180 GHz. A lack of spatial resolution typical of the former geometry has to be contrasted with a significant limitation in plasma access typical of the remaining geometries. Other relevant differences concern the requirements in terms of gyrotron power, acceptable stray radiation levels, etc. Special emphasis is given in the work to a discussion of ECE noise, on which the feasibility itself of the alpha collective scattering diagnostics at mm-waves largely depends in the plasma regimes considered. {copyright} {ital 1996 American Institute of Physics.}

  8. Transport processes in well confined high temperature plasmas and collective modes in their partially ionized edge region

    NASA Astrophysics Data System (ADS)

    Daughton, William Scott

    1998-12-01

    of conditions, a novel form of a thermal transport coefficient which reproduces both ohmic and auxiliary heated L-mode discharges has been identified. This thermal transport coefficient involves the difference of two terms, one representing the normal outward diffusion of thermal energy and the other corresponding to a process reducing the outward flux. The coefficient includes the constraint of profile consistency. In a series of transport simulations for plasmas produced by the Alcator C-Mod machine, the thermal transport coefficient is shown to reproduce the observed electron temperature profile, stored energy and loop voltage. The relevant scaling for the energy confinement time is also composed of two terms. The L- mode database assembled for the ITER project is used to compare DIII-D, JET, JT60, PDX, TFTR, FTU, and Alcator C- Mod with this analysis. With the exception of PDX, the comparison is substantially better than standard L-mode power law scalings. Based on this analysis, an extrapolation is made for the confinement time of two proposed ignition experiments. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.) (Abstract shortened by UMI.)

  9. Composition of the source region plasma in inertial electrostatic confinement devices

    SciTech Connect

    Boris, D. R.; Emmert, G. A.

    2008-08-15

    The ion species composition in the source region of inertial electrostatic confinement (IEC) devices plays an important role in the atomic and molecular physics processes in the device and in the resulting energy spectrum of the fast ions and the neutron production rate. A zero dimensional rate equation model for the ion species composition in the source region of IEC devices is presented and compared with experimental measurements on the Wisconsin IEC device [J. F. Santarius, G. L. Kulcinski, R. P. Ashley et al., Fusion Sci. Tech. 47, 1238 (2005)]. The ion species composition is measured using an ion acoustic wave diagnostic; the results are in good agreement with the theoretical predictions. Both the theory and the experimental results show that D{sub 3}{sup +} ions are the majority species in the source region.

  10. Radiative power losses from impurities in high-density plasmas confined by high magnetic fields

    NASA Astrophysics Data System (ADS)

    May, Mark Joseph

    1998-07-01

    Quantifying and controlling the radiative power losses from impurities in the tokamak fusion plasma is crucial for obtaining ignition conditions. In the present work, therefore, losses from impurities have been measured in different operating regimes of the Alcator C-Mod Tokamak and the Frascati Tokamak Upgrade (FTU) plasmas. The major radiating intrinsic impurity in both tokamaks was molybdenum sputtered from the armor tiles covering all the plasma facing surfaces. The radiative power losses from the molybdenum ions accounted for [>]80/% of the total radiative power losses in ICRF heated plasmas and ~60/% in ohmically heated plasmas. Molybdenum could radiate as much as several thousand kW with concentrations as high as ~1× 1011/ particles/cm3 or ~0.001 of the plasma (electron) density. The radiative losses were found to increase linearly with increasing ICRF power and to vary weakly with the central electron density of the plasma. The other major intrinsic impurities in Alcator C-Mod Tokamak, carbon and boron, radiated at most ~100 kW from the plasma and had concentrations in ohmically heated plasmas of ~1.7× 10/ particles/cm3 and ~6.3× 1011/ particles/cm3, respectively. At Alcator C-Mod Tokamak, the total radiative power losses were measured with bolometric systems. The contribution to the total radiative losses from each major impurity and the impurity concentrations were determined spectroscopically from the line brightnesses of XUV (soft X-ray and extreme ultraviolet) transitions. The line brightnesses were interpreted via a detailed atomic physics model which included the Multiple Ionization State Transport (MIST) code, the ab initio atomic rates from the Hebrew University-Jerusalem Lawrence Livermore Atomic Code (HULLAC) and a collisional radiative model. At the FTU Tokamak, brightnesses from impurity emission measured with an X-ray crystal spectrometer were interpreted with a similar atomic physics model which included the molybdenum rates from HULLAC

  11. Progress on the physics of ignition for radiation driven inertial confinement fusion (ICF) targets

    SciTech Connect

    Lindl, J.D.; Marinak, M.M.

    1996-09-01

    Extensive modeling of proposed National Ignition Facility (NIF) ignition targets has resulted in a variety of targets using different materials in the fuel shell, using driving temperatures which range from 250-300 eV, and requiring energies from < 1 MJ up to the full 1. 8 MJ design capability of NIF. Recent Nova experiments have shown that hohlraum walls composed of a mixture of high-z materials could result in targets which require about 20% less energy. Nova experiments are being used to quantify benefits of beam smoothing in reducing stimulated scattering processes and laser beam filamentation for proposed gas-filled hohlraum targets on NIF. Use of Smoothing by Spectral Dispersion with 2-3 {Angstrom}of bandwidth results in <4-5% of Stimulated Raman Scattering and less than about 1% Stimulated Brillouin Scattering for intensities less than about 2x10{sup 15}W/cm{sup 2} for this type of hohlraum. The symmetry in Nova gas- filled hohlraums is affected by the gas fill. A large body of evidence now exists which indicates that this effect is due to laser beam filamentation which can be largely controlled by beam smoothing. We present here the firs 3-D simulations of hydrodynamic instability for the NIF point design capsule. These simulations, with the HYDRA radiation hydrodynamics code, indicate that spikes can penetrate up to 10 {mu}m into the 30{mu}m radius hot spot before ignition is quenched. Using capsules whose surface is modified by laser ablation, Nova experiments have been used to quantify the degradation of implosions subject to near NIF levels of hydrodynamic instability.

  12. Synthesis of Functional Surfaces via Click Chemistry and Fabrication of Inertial Confinement Fusion Targets

    NASA Astrophysics Data System (ADS)

    Tucker-Schwartz, Alexander Kevin

    inertial confinement fusion (ICF) and high energy density experiments. The current methods for synthesizing ICF shells are only able to produce low yields of shells with acceptable physical specification required for ICF experiments. These fabrication methods are also time consuming, tedious, and expensive. A new method that utilizes electric fields to controllably and perfectly center the inner droplet of double emulsion (DE) droplets was developed. Electric field-centered DE droplets were shown to meet the sphericity and shell uniformity requirements for ICF shells. The centered DE droplets were formed using a polymerizable outer liquid shell, which could be photopolymerized into a solid shell. Polymerized shells were found to meet the ICF sphericity requirements but fell just short of the shell wall thickness uniformity requirement. Nonetheless, electric field-driven DE droplet centering and polymerization has the potential to be an extremely useful approach for forming large numbers ICF shells.

  13. Non-resonant elastic scattering of low-energy photons by atomic sodium confined in quantum plasmas

    SciTech Connect

    Ghosh, Avijit Ray, Debasis

    2015-03-15

    The non-resonant elastic scattering of low-energy photons by the bound valence electron in the ground state 3s of atomic sodium confined in quantum plasmas is investigated theoretically. The incident photon energy is assumed to be much smaller than the 3s-3p excitation energy. The alkali atom sodium is first formulated as an effective one-electron problem in which the attractive interaction between the valence electron and the atomic ion core is simulated by a spherically symmetric model potential. The Shukla-Eliasson oscillatory exponential cosine screened-Coulomb potential model is then used to mimic the effective two-body (valence-core) interaction within quantum plasmas. Non-relativistic calculations performed within the electric dipole approximation indicate that the non-resonant elastic photon scattering cross-section undergoes a dramatic growth by several orders of magnitude as the quantum wave number increases. A qualitative explanation of this phenomenon is presented. In the absence of the oscillatory cosine screening term, a similar growth is observed at larger values of the quantum wave number. Our computed relevant atomic data are in very good agreement with the experimental as well as the previous theoretical data for the zero-screening (free atom) case, and with the very limited, accurate theoretical results available for the case of exponential screened-Coulomb two-body interaction, without the cosine screening term.

  14. The impact of laser plasma interactions on three-dimensional drive symmetry in inertial confinement fusion implosions

    SciTech Connect

    Peterson, J. L. Michel, P.; Thomas, C. A.; Town, R. P. J.

    2014-07-15

    Achieving symmetric hohlraum radiation drive is an important aspect of indirectly driven inertial confinement fusion experiments. However, when experimentally delivered laser powers deviate from ideal conditions, the resultant radiation field can become asymmetric. Two situations in which this may arise are random uncorrelated fluctuations, in as-delivered laser power and laser beams that do not participate in the implosion (either intentionally or unintentionally). Furthermore, laser plasma interactions in the hohlraum obfuscate the connection between laser powers and radiation drive. To study the effect of these situations on drive symmetry, we develop a simplified model for crossed-beam energy transfer, laser backscatter, and plasma absorption that can be used in conjunction with view factor calculations to expediently translate laser powers into three-dimensional capsule flux symmetries. We find that crossed-beam energy transfer can alter both the statistical properties of uncorrelated laser fluctuations and the impact of missing laser beams on radiation symmetry. A method is proposed to mitigate the effects of missing laser beams.

  15. Mitigation of Laser Imprinting with Diamond Ablator for Direct-Drive Inertial Confinement Fusion Targets

    NASA Astrophysics Data System (ADS)

    Shigemori, K.; Kato, H.; Nakai, M.; Hosogi, R.; Sakaiya, T.; Terasaki, H.; Fujioka, S.; Sunahara, A.; Azechi, H.

    2016-03-01

    We propose a novel scheme to mitigate the initial perturbation imprinting due to irradiation non-uniformity. Diamond was potential candidate for the ablator material for ICF targets due to its stiffness. The stiffness is very important parameter for imprint mitigation because the laser imprint is primary as a function of pressure perturbation due to lase irradiation non-uniformity. We measured the imprint amplitude of diamond foils and plastic (CH) foils. The experimental data suggest the initial imprinting is drastically mitigated for the diamond foils.

  16. WITHDRAWN--Molecular dynamics simulations of transport in highly asymmetric plasma mixtures: Application to double-shell ignition targets

    NASA Astrophysics Data System (ADS)

    Bastea, Sorin

    2005-10-01

    Dense plasma mixtures are often encountered in the study of inertial confinement fusion (ICF) and in many astrophysical environments. Evaluating the associated transport coefficients is important for understanding the performance of ICF targets, in particular double-shell ignition target designs [1]. However, such an assessment is often very difficult when the mixed plasma is highly asymmetric in charge and mass, as in the DT fuel and Au pusher of an ignition double shell. We present molecular dynamics simulation results [2] for the viscosity and mutual diffusion of a DT/Au mixture after deceleration onset, modeled as a binary ionic mixture. Compared with previous one-component plasma models [3], the predicted viscosity and mutual diffusivity are considerably higher and tend to reduce the Rayleigh-Taylor instability growth rates based on the model of Duff, Harlow and Hirt [4]. Mode cutoffs near 10^3 are predicted on the fuel-pusher interface, leading to the prospect of realistic multimode simulations of instability growth. [1[ P. Amendt et al., Phys. Plasmas 9, 2221 (2002). [2] S. Bastea, Phys. Rev. E 71, 056405 (2005). [3] J.G. Cl'erouin, M.H. Cherfi, G. Z'erah, Europhys. Lett. 42, 37 (1998). [4] R.E. Duff, F.H. Harlow, C.W. Hirt, Phys. Fluids 5, 417 (1962). 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.

  17. Laser tracker orientation in confined space using on-board targets

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Kyle, Stephen; Lin, Jiarui; Yang, Linghui; Ren, Yu; Zhu, Jigui

    2016-08-01

    This paper presents a novel orientation method for two laser trackers using on-board targets attached to the tracker head and rotating with it. The technique extends an existing method developed for theodolite intersection systems which are now rarely used. This method requires only a very narrow space along the baseline between the instrument heads, in order to establish the orientation relationship. This has potential application in environments where space is restricted. The orientation parameters can be calculated by means of two-face reciprocal measurements to the on-board targets, and measurements to a common point close to the baseline. An accurate model is then applied which can be solved through nonlinear optimization. Experimental comparison has been made with the conventional orientation method, which is based on measurements to common intersection points located off the baseline. This requires more space and the comparison has demonstrated the feasibility of the more compact technique presented here. Physical setup and testing suggest that the method is practical. Uncertainties estimated by simulation indicate good performance in terms of measurement quality.

  18. Inertia driven radial breathing and nonlinear relaxation in cylindrically confined pure electron plasma

    SciTech Connect

    Sengupta, M.; Ganesh, R.

    2014-02-15

    The dynamics of cylindrically trapped electron plasma has been investigated using a newly developed 2D Electrostatic PIC code that uses unapproximated, mass-included equations of motion for simulation. Exhaustive simulations, covering the entire range of Brillouin ratio, were performed for uniformly filled circular profiles in rigid rotor equilibrium. The same profiles were then loaded away from equilibrium with an initial value of rigid rotation frequency different from that required for radial force balance. Both these sets of simulations were performed for an initial zero-temperature or cold load of the plasma with no spread in either angular velocity or radial velocity. The evolution of the off-equilibrium initial conditions to a steady state involve radial breathing of the profile that scales in amplitude and algebraic growth with Brillouin fraction. For higher Brillouin fractions, the growth of the breathing mode is followed by complex dynamics of spontaneous hollow density structures, excitation of poloidal modes, leading to a monotonically falling density profile.

  19. Inertia driven radial breathing and nonlinear relaxation in cylindrically confined pure electron plasma

    SciTech Connect

    Sengupta, M.; Ganesh, R.

    2015-06-29

    The dynamics of cylindrically trapped electron plasma has been investigated using a newly developed 2D Electrostatic PIC code that uses unapproximated, mass-included equations of motion for simulation. Exhaustive simulations, covering the entire range of Brillouin ratio, were performed for uniformly filled circular profiles in rigid rotor equilibrium. The same profiles were then loaded away from equilibrium with an initial value of rigid rotation frequency different from that required for radial force balance. Both these sets of simulations were performed for an initial zero-temperature or cold load of the plasma with no spread in either angular velocity or radial velocity. The evolution of the off-equilibrium initial conditions to a steady state involve radial breathing of the profile that scales in amplitude and algebraic growth with Brillouin fraction. For higher Brillouin fractions, the growth of the breathing mode is followed by complex dynamics of spontaneous hollow density structures, excitation of poloidal modes, leading to a monotonically falling density profile.

  20. Nonthermal Plasma-Mediated Cancer Cell Death; Targeted Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Choi, Byul-Bora; Choi, Yeon-Sik; Lee, Hae-Jun; Lee, Jae-Koo; Kim, Uk-Kyu; Kim, Gyoo-Cheon

    Non-thermal air plasma can kill cancer cells. However, there is no selectivity between normal and cancer cells. Therefore, cancer specific antibody conjugated gold nanoparticle (GNP) was pretreated before plasma irradiation. Stimulation of antibody conjugated GNP by plasma treatment resulted in a significant decrease in viability of cancer cells. This technology shows the feasibility of using plasma therapy for killing cancer cells selectively.

  1. Time-dependent filamentation and stimulated Brillouin forward scattering in inertial confinement fusion plasmas

    NASA Astrophysics Data System (ADS)

    Schmitt, Andrew J.; Afeyan, Bedros B.

    1998-02-01

    Numerical simulations of the temporal evolution of laser light filamentation and stimulated Brillouin forward scattering (SBFS) in plasmas, under conditions that are relevant to laser fusion, are presented and analyzed. Long term unsteady behavior of filaments is observed to be the norm. Temporal and spatial incoherence due to filamentation and SBFS are impressed upon time-independent incident laser beams. The bandwidth and angular divergence imposed upon the beam increase with the strength of the interaction. In addition, the spectrum of the transmitted light is redshifted by an amount that increases with the interaction strength. Spectral analysis of the transmitted light reveals that SBFS plays a role in the generation of the observed temporal incoherence. Incident beams with some spatial incoherence but no temporal smoothing are compared to those with ab initio temporal beam smoothing (TBS). Under typical conditions, TBS beams will undergo far less angular and spectral spreading and far less SBFS than unsmoothed beams.

  2. Spectroscopic study of molecular-hydrogen processes in a mirror-confined plasma

    SciTech Connect

    Moran, T.G. |

    1995-04-01

    Visible and near-ultraviolet molecular hydrogen emission from the Tara Tandem Mirror central cell plasma was investigated in order to determine molecular densities, ionization rates, and continuum dissociation rates. Measurements of H{sub 2} {ital G}{r_arrow}{ital B} band emission were used to infer spatial density and ionization profiles, maximum densities of 4{times}10{sup 12} cm{sup {minus}3} at the gas injection port, and a total molecular ionization rate of 254 A. Continuum emission in the near ultraviolet was identified as the H{sub 2} dissociative continuum through its wavelength distribution, time behavior, and intensity. Wavelength-integrated continuum emission measurements were used to obtain the dissociation rate associated with the continuum: 6 A. The power expended in molecular ionization, dissociation, and radiation is estimated to be 8.4 kW out of 300 kW of rf power injected.

  3. Abrupt onset of tongue deformation and phase space response of ions in magnetically-confined plasmas

    PubMed Central

    Ida, K.; Kobayashi, T.; Itoh, K.; Yoshinuma, M.; Tokuzawa, T.; Akiyama, T.; Moon, C.; Tsuchiya, H.; Inagaki, S.; Itoh, S.-I.

    2016-01-01

    An abrupt onset of the new tongue-shaped deformation of magnetic surface in magnetized plasmas, which was conjectured in since the 1960s but has not been observed, is experimentally identified just before an abrupt onset of a large-scale collapse event. Two novel properties of the event are identified. First, the transition of symmetry of perturbation (rather than a growth of linearly unstable MHD modes) was found to be a key for the onset of abrupt collapse, i.e., the transition of symmetry gives a new route to the collapse from stable state. Second, as a phase-space response of ions, the distortion from Maxwell-Boltzmann distribution of epithermal ions was observed for the first time. PMID:27796370

  4. Experimental verification of the Boltzmann relation in confined plasmas: Comparison of noble and molecule gases

    SciTech Connect

    Lee, Hyo-Chang; Hwang, Hye-Ju; Kim, Young-Cheol; Kim, June Young; Kim, Dong-Hwan; Chung, Chin-Wook

    2013-03-15

    Experimental verification of the Boltzmann relation is performed in argon and oxygen gas inductively coupled plasmas from the measurements of both the spatial electron currents (as a fluid approach) and the electron energy probability functions (EEPFs, as a kinetic approach). At a low gas pressure of 10 mTorr, the measured electron currents are spatially uniform, and the EEPFs in the total electron energy scale are identical, which indicate that the Boltzmann relation is valid at both the argon and oxygen gases. As the gas pressure increases to 30-40 mTorr, however, the Boltzmann relation is broken in the oxygen gas discharge, while the Boltzmann relation is still valid in the argon gas discharge. This different variation in the oxygen gas discharge is mainly due to the presence of various inelastic collisions in the entire electron energy region, which causes the transition of the electron kinetics from a non-local to a local regime.

  5. Capacitor Bank 'CHANDI' for Plasma Target Production for Liner Plasma Interaction

    SciTech Connect

    Shukla, R.; Sharma, S.K.; Debnath, K.; Shyam, A.

    2006-01-05

    A capacitor bank is fabricated to drive (JXB) Plasma gun to generate hot plasma (target) for liner plasma investigation. The bank will also be used for driving other pintch experiments. The bank consists of 8 capacitors connected in parallel, each having capacitance of 178 {mu}F giving a total of 1424uF. The bank is charged at 15 kV using a 28 kV power supply charging the capacitors in 65 seconds utilizing full wave charging technique. The total energy of the bank is 160kJ at 15kV. A modeling of power supply was done so that all the components involved are utilized to their operating limit safely. Moreover to give fault protection to the capacitor bank we have implemented the neutral control technique in the power supply. The capacitor bank is discharged to the inductive load through an ignitron switch of very high coulomb rating and capable of withstanding high voltages at its electrodes. The cables used for connecting capacitor bank with ignitron switch are used in parallel to give them collective capability of bearing capacitor discharge currents. These cables are capable of holding high DC voltages (40kV), which appear at the time of charging of the bank. The bank is tested and is operational.

  6. Thermo-statistical study of evaporation effects in a non neutral plasma under an imperfect magnetic confinement

    NASA Astrophysics Data System (ADS)

    Ordenes-Huanca, C.; Velazquez, L.

    2016-09-01

    Experimental studies of non-neutral plasmas in magnetic traps undergo, in some degree of affectation, the incidence of evaporation. For example, the existence of a finite threshold energy {{\\varepsilon}c} for the escaping of plasma constituents can be favored by the external electrostatic forces near the grounded conducting walls of a cylindrical Penning trap. In contrast, the conventional statistical mechanics description of these situations is performed assuming the existence of a rigorous thermodynamic equilibrium (Dubin and O’Neil 1999 Rev. Mod. Phys. 71 87), dismissing thus the existence of evaporation effects. We propose in this work a two-dimensional toy model that describes the incidence of evaporation on thermo-statistics of a pure non-neutral plasma (a system composed of a single charge species like an infinitely long electron column). Considering the existing connections between the macroscopic descriptions of pure non-neutral plasmas and astrophysical systems, the treatment of evaporation along a quasi-stationary regime is developed here in analogy to some astrophysical models proposed in the literature. We start from a regularized microcanonical description that only considers those microscopic configurations where particles are trapped inside a confinement region of radius R c , which is implemented introducing a truncation of their velocity spectrum. These arguments lead us to a statistical procedure to predict the quasi-stationary particles distribution n≤ft(\\mathbf{r}\\right) similar to the maximum entropy approach. According to our analysis, the influence of evaporation for a non-zero temperature T crucially depends on the saturation parameter δ ={{r}\\text{B}}/{{R}c} , whose admissible values are located in the interval 0<δ <1 , with r B being the radius of Billouin steady state that appears in the limit T\\to 0 . The theoretical profiles predicted from this model are then compared to the metastable radial density distribution reported by

  7. Gaussian beams for a linearized cold plasma confined in a torus

    NASA Astrophysics Data System (ADS)

    Cardinali, A.; Dobrokhotov, S. Yu.; Klevin, A.; Tirozzi, B.

    2016-04-01

    We consider a system of linear pde describing a cold plasma in a toroidal region in three-dimensional space. This system simulates the passage of a laser beam through the TOKAMAK, it consists of 9 equations for the electric field and the velocities of electrons and ions in a given magnetic field. Asymptotic solutions describing high-frequency Gaussian beams are constructed using the theory of Maslov complex germ in a fairly effective form. The solutions of the system are localized in the neighborhood of the beam passing through the toroidal domain (the camera). The equations for a ray take into account the density of particles in the camera and don't ``feel'' the presence of the magnetic field because of the high frequency of the Gaussian beam; the dependence on the magnetic field is contained in the amplitude of the electric field. Before the TOKAMAK camera the amplitude of the Gaussian beam is the same as in free space, but after the camera the amplitude vector rotates under the influence of the magnetic field. The formula for the angle of rotation is given explicitly. An analytical-numerical algorithm based on the asymptotic solutions is used to analyze the parameters of the magnetic field in the TOKAMAK.

  8. A self-organized criticality model for ion temperature gradient mode driven turbulence in confined plasma

    SciTech Connect

    Isliker, H.; Pisokas, Th.; Vlahos, L.; Strintzi, D.

    2010-08-15

    A new self-organized criticality (SOC) model is introduced in the form of a cellular automaton (CA) for ion temperature gradient (ITG) mode driven turbulence in fusion plasmas. Main characteristics of the model are that it is constructed in terms of the actual physical variable, the ion temperature, and that the temporal evolution of the CA, which necessarily is in the form of rules, mimics actual physical processes as they are considered to be active in the system, i.e., a heating process and a local diffusive process that sets on if a threshold in the normalized ITG R/L{sub T} is exceeded. The model reaches the SOC state and yields ion temperature profiles of exponential shape, which exhibit very high stiffness, in that they basically are independent of the loading pattern applied. This implies that there is anomalous heat transport present in the system, despite the fact that diffusion at the local level is imposed to be of a normal kind. The distributions of the heat fluxes in the system and of the heat out-fluxes are of power-law shape. The basic properties of the model are in good qualitative agreement with experimental results.

  9. Investigation of electron-beam charging for inertial-confinement-fusion targets. Charged Particle Research Laboratory report No. 3-82

    SciTech Connect

    Kim, K.; Elsayed-Ali, H.E.

    1982-04-01

    Techniques for charging inertial confinement fusion targets using electron beam are investigated. A brief review of the various possible charging techniques is presented, along with a discussion of the advantages and disadvantages of each. The reasons for selecting the electron beam charging and a physical picture of the charging mechanism are described. Experimental results are presented and compared with the theoretical predictions.

  10. LDRD final report on confinement of cluster fusion plasmas with magnetic fields.

    SciTech Connect

    Argo, Jeffrey W.; Kellogg, Jeffrey W.; Headley, Daniel Ignacio; Stoltzfus, Brian Scott; Waugh, Caleb J.; Lewis, Sean M.; Porter, John Larry, Jr.; Wisher, Matthew; Struve, Kenneth William; Savage, Mark Edward; Quevedo, Hernan J.; Bengtson, Roger

    2011-11-01

    Two versions of a current driver for single-turn, single-use 1-cm diameter magnetic field coils have been built and tested at the Sandia National Laboratories for use with cluster fusion experiments at the University of Texas in Austin. These coils are used to provide axial magnetic fields to slow radial loss of electrons from laser-produced deuterium plasmas. Typical peak field strength achievable for the two-capacitor system is 50 T, and 200 T for the ten-capacitor system. Current rise time for both systems is about 1.7 {mu}s, with peak current of 500 kA and 2 MA, respectively. Because the coil must be brought to the laser, the driver needs to be portable and drive currents in vacuum. The drivers are complete but laser-plasma experiments are still in progress. Therefore, in this report, we focus on system design, initial tests, and performance characteristics of the two-capacitor and ten-capacitors systems. The questions of whether a 200 T magnetic field can retard the breakup of a cluster-fusion plasma, and whether this field can enhance neutron production have not yet been answered. However, tools have been developed that will enable producing the magnetic fields needed to answer these questions. These are a two-capacitor, 400-kA system that was delivered to the University of Texas in 2010, and a 2-MA ten-capacitor system delivered this year. The first system allowed initial testing, and the second system will be able to produce the 200 T magnetic fields needed for cluster fusion experiments with a petawatt laser. The prototype 400-kA magnetic field driver system was designed and built to test the design concept for the system, and to verify that a portable driver system could be built that delivers current to a magnetic field coil in vacuum. This system was built copying a design from a fixed-facility, high-field machine at LANL, but made to be portable and to use a Z-machine-like vacuum insulator and vacuum transmission line. This system was sent to the

  11. Power Coupling of the Rotating Magnetic Field to the Plasma in the Translation, Confinement and Sustainment Experiment

    NASA Astrophysics Data System (ADS)

    Tobin, Stephen; Schrank, Louis; Wurden, Glen; Brooks, Bob; Crawford, Ed; Guo, Houyang; Hoffman, Alan; Lotz, Dan; Slough, John; Votroubek, George

    2000-10-01

    Experimental results utilizing the rotating magnetic field (RMF) current drive system at TCS are presented. The procedure at TCS is to form a hot, FRC (RFTP method); translate it to the confinement chamber; then drive a poloidal current in it with a RMF so that the magnetic flux is sustained. The goal is to sustain the flux so that the lifetime of the FRC becomes limited by particle inventory rather that resistive flux losses, as is presently the case. In addition, the RMF can form FRCs from a pre-ionized gas fill. Experiments to date have been conducted with the following properties: RMF field strengths of about 25 G (1 mWb flux), densities of about 0.5x10^19 m-3, electron temperatures of about 100 eV, and external fields of 150 G. This poster will address the coupling of the RMF power to the plasma, in particular, how this coupling varies with density and RMF properties (field strength, frequency, pulse width and relative phasing).

  12. Confined diffusion of transmembrane proteins and lipids induced by the same actin meshwork lining the plasma membrane.

    PubMed

    Fujiwara, Takahiro K; Iwasawa, Kokoro; Kalay, Ziya; Tsunoyama, Taka A; Watanabe, Yusuke; Umemura, Yasuhiro M; Murakoshi, Hideji; Suzuki, Kenichi G N; Nemoto, Yuri L; Morone, Nobuhiro; Kusumi, Akihiro

    2016-04-01

    The mechanisms by which the diffusion rate in the plasma membrane (PM) is regulated remain unresolved, despite their importance in spatially regulating the reaction rates in the PM. Proposed models include entrapment in nanoscale noncontiguous domains found in PtK2 cells, slow diffusion due to crowding, and actin-induced compartmentalization. Here, by applying single-particle tracking at high time resolutions, mainly to the PtK2-cell PM, we found confined diffusion plus hop movements (termed "hop diffusion") for both a nonraft phospholipid and a transmembrane protein, transferrin receptor, and equal compartment sizes for these two molecules in all five of the cell lines used here (actual sizes were cell dependent), even after treatment with actin-modulating drugs. The cross-section size and the cytoplasmic domain size both affected the hop frequency. Electron tomography identified the actin-based membrane skeleton (MSK) located within 8.8 nm from the PM cytoplasmic surface of PtK2 cells and demonstrated that the MSK mesh size was the same as the compartment size for PM molecular diffusion. The extracellular matrix and extracellular domains of membrane proteins were not involved in hop diffusion. These results support a model of anchored TM-protein pickets lining actin-based MSK as a major mechanism for regulating diffusion.

  13. Confined diffusion of transmembrane proteins and lipids induced by the same actin meshwork lining the plasma membrane

    PubMed Central

    Fujiwara, Takahiro K.; Iwasawa, Kokoro; Kalay, Ziya; Tsunoyama, Taka A.; Watanabe, Yusuke; Umemura, Yasuhiro M.; Murakoshi, Hideji; Suzuki, Kenichi G. N.; Nemoto, Yuri L.; Morone, Nobuhiro; Kusumi, Akihiro

    2016-01-01

    The mechanisms by which the diffusion rate in the plasma membrane (PM) is regulated remain unresolved, despite their importance in spatially regulating the reaction rates in the PM. Proposed models include entrapment in nanoscale noncontiguous domains found in PtK2 cells, slow diffusion due to crowding, and actin-induced compartmentalization. Here, by applying single-particle tracking at high time resolutions, mainly to the PtK2-cell PM, we found confined diffusion plus hop movements (termed “hop diffusion”) for both a nonraft phospholipid and a transmembrane protein, transferrin receptor, and equal compartment sizes for these two molecules in all five of the cell lines used here (actual sizes were cell dependent), even after treatment with actin-modulating drugs. The cross-section size and the cytoplasmic domain size both affected the hop frequency. Electron tomography identified the actin-based membrane skeleton (MSK) located within 8.8 nm from the PM cytoplasmic surface of PtK2 cells and demonstrated that the MSK mesh size was the same as the compartment size for PM molecular diffusion. The extracellular matrix and extracellular domains of membrane proteins were not involved in hop diffusion. These results support a model of anchored TM-protein pickets lining actin-based MSK as a major mechanism for regulating diffusion. PMID:26864625

  14. Block Ignition Inertial Confinement Fusion (ICF) with Condensed Matter Cluster Type Targets for p-B11 Powered Space Propulsion

    SciTech Connect

    Miley, George H.; Hora, H.; Badziak, J.; Wolowski, J.; Sheng Zhengming; Zhang Jie; Osman, F.; Zhang Weiyan; Tuhe Xia

    2009-03-16

    The use of laser-driven Inertial Confinement Fusion (ICF) for space propulsion has been the subject of several earlier conceptual design studies, (see: Orth, 1998; and other references therein). However, these studies were based on older ICF technology using either 'direct' or 'in-direct x-ray driven' type target irradiation. Important new directions have opened for laser ICF in recent years following the development of 'chirped' lasers capable of ultra short pulses with powers of TW up to few PW which leads to the concept of 'fast ignition (FI)' to achieve higher energy gains from target implosions. In a recent publication the authors showed that use of a modified type of FI, termed 'block ignition' (Miley et al., 2008), could meet many of the requirements anticipated (but not then available) by the designs of the Vehicle for Interplanetary Space Transport Applications (VISTA) ICF fusion propulsion ship (Orth, 2008) for deep space missions. Subsequently the first author devised and presented concepts for imbedding high density condensed matter 'clusters' of deuterium into the target to obtain ultra high local fusion reaction rates (Miley, 2008). Such rates are possible due to the high density of the clusters (over an order of magnitude above cryogenic deuterium). Once compressed by the implosion, the yet higher density gives an ultra high reaction rate over the cluster volume since the fusion rate is proportional to the square of the fuel density. Most recently, a new discovery discussed here indicates that the target matrix could be composed of B{sup 11} with proton clusters imbedded. This then makes p-B{sup 11} fusion practical, assuming all of the physics issues such as stability of the clusters during compression are resolved. Indeed, p-B{sup 11} power is ideal for fusion propulsion since it has a minimum of unwanted side products while giving most of the reaction energy to energetic alpha particles which can be directed into an exhaust (propulsion) nozzle

  15. Neutron Time-of-Flight Measurements of Charged-Particle Energy Loss in Inertial Confinement Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Sayre, Daniel; Cerjan, Charlie; Berzak Hopkins, Laura; Caggiano, Joseph; Divol, Laurent; Eckart, Mark; Graziani, Frank; Grim, Gary; Hartouni, Ed; Hatarik, Robert; Le Pape, Sebastien; MacKinnon, Andrew; Schneider, Dieter; Sepke, Scott

    2015-11-01

    Neutron time-of-flight measurements of inflight T (d , n) α reactions created during an implosion of a deuterium gas target have been performed at the National Ignition Facility, with order of magnitude improvements in statistics and resolution over past experiments. In the implosion, energetic tritons emitted by thermonuclear fusion within the deuterium plasma produced over 1011 inflight T (d , n) α reactions. The yield and particle spectrum of inflight reactions are sensitive to the triton's energy loss in the plasma, which, in this implosion, consisted of multi-keV temperatures and number densities above 1024 cm-3. Radiation-hydrodynamic simulations of the implosion were adjusted to match the yield and broadening of the D (d , n) 3 He neutron peak. These same simulations give reasonable agreement with the measured T (d , n) α yield and neutron spectrum, and this provides a strong consistency check of the simulated plasma conditions and energy loss model. This research was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Analyses of the plasma generated by laser irradiation on sputtered target for determination of the thickness used for plasma generation

    SciTech Connect

    Kumaki, Masafumi; Ikeda, Shunsuke; Sekine, Megumi; Munemoto, Naoya; Fuwa, Yasuhiro; Cinquegrani, David; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2014-02-15

    In Brookhaven National Laboratory, laser ion source has been developed to provide heavy ion beams by using plasma generation with 1064 nm Nd:YAG laser irradiation onto solid targets. The laser energy is transferred to the target material and creates a crater on the surface. However, only the partial material can be turned into plasma state and the other portion is considered to be just vaporized. Since heat propagation in the target material requires more than typical laser irradiation period, which is typically several ns, only the certain depth of the layers may contribute to form the plasma. As a result, the depth is more than 500 nm because the base material Al ions were detected. On the other hand, the result of comparing each carbon thickness case suggests that the surface carbon layer is not contributed to generate plasma.

  17. The mitigating effect of self-generated magnetic field on Rayleigh-Taylor unstable inertial confinement fusion plasmas

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bhuvana

    2012-10-01

    It has long been expected that Rayleigh-Taylor instabilities (RTI) in ICF can generate magnetic fields at the gas-ice interface and at the ice-ablator interface during the deceleration phase of target implosion. The focus here is on the gas-ice interface where the temperature gradient is the largest. Nonlinear evolution of RTI leads to undesirable mixing of hot and cold plasmas and enhances target energy loss. RTI is also expected to generate magnetic fields via the Biermann battery effect, which is related to fluid vorticity generation by RTI. The magnetic field wraps around the bubbles and spikes and concentrates in flux bundles at the perturbed gas-ice interface where fluid vorticity is large. The generated magnetic field can then be further amplified via the MHD dynamo effect. While the planar 2-D simulations only generate out-of-plane magnetic fields, 3-D simulations will result in further amplification of the complex magnetic field structures via the MHD dynamo. This is studied by including a seed in-plane magnetic field in 2-D and examining the resulting magnetic field structure and magnitude. The self-generated out-of-plane magnetic fields depend on ICF parameters via the scaling law, mi√A g/λ where mi is the ion mass, A is the Atwood number, g is the acceleration, and λ is the wavelength. These magnetic fields grow to magnitudes of 10^2-10^3 T for ICF relevant parameter regimes. While this is dynamically insignificant due to the plasma pressure far exceeding the magnetic pressure, it can significantly reduce perpendicular electron thermal conductivity by a factor of 2-10. Such a reduction in thermal conductivity perpendicular to the magnetic field contributes to lowering of radial energy transport in the implosion target.

  18. The roles of electric field shear and Shafranov shift in sustaining high confinement in enhanced reversed shear plasmas on the TFTR tokamak

    SciTech Connect

    Synakowski, E.J.; Beer, M.A.; Batha, S.H.

    1997-02-01

    The relaxation of core transport barriers in TFTR Enhanced Reversed Shear plasmas has been studied by varying the radial electric field using different applied torques from neutral beam injection. Transport rates and fluctuations remain low over a wide range of radial electric field shear, but increase when the local E x B shearing rates are driven below a threshold comparable to the fastest linear growth rates of the dominant instabilities. Shafranov-shift-induced stabilization alone is not able to sustain enhanced confinement.

  19. The geometrical-optics law of reflection for electromagnetic waves in magnetically confined plasmas: Specular reflection of rays at the last closed flux surface

    SciTech Connect

    Bizarro, Joao P. S.

    2010-10-15

    Within the geometrical-optics approximation, it is shown that the reflection of rays describing the propagation of electromagnetic waves in fusion-grade, magnetically confined plasmas and impinging on the last closed flux surface, or plasma surface, is necessarily specular or mirror-like. More precisely, the component of the wave vector tangential to that surface does not change, whereas the component normal to it reverses its sign while keeping its magnitude. The well-known law of reflection, stating that the angle of incidence equals that of reflection, is thus generalized to anisotropic media.

  20. Measurement of plasma momentum exerted on target by a small helicon plasma thruster and comparison with direct thrust measurement.

    PubMed

    Takahashi, Kazunori; Komuro, Atsushi; Ando, Akira

    2015-02-01

    Momentum, i.e., force, exerted from a small helicon plasma thruster to a target plate is measured simultaneously with a direct thrust measurement using a thrust balance. The calibration coefficient relating a target displacement to a steady-state force is obtained by supplying a dc to a calibration coil mounted on the target, where a force acting to a small permanent magnet located near the coil is directly measured by using a load cell. As the force exerted by the plasma flow to the target plate is in good agreement with the directly measured thrust, the validity of the target technique is demonstrated under the present operating conditions, where the thruster is operated in steady-state. Furthermore, a calibration coefficient relating a swing amplitude of the target to an impulse bit is also obtained by pulsing the calibration coil current. The force exerted by the pulsed plasma, which is estimated from the measured impulse bit and the pulse width, is also in good agreement with that obtained for the steady-state operation; hence, the thrust assessment of the helicon plasma thruster by the target is validated for both the steady-state and pulsed operations. PMID:25725840

  1. Target Monitoring and Plasma Diagnosis using 2ω probe beam for CANDY

    NASA Astrophysics Data System (ADS)

    Ishii, Katsuhiro; Mori, Yoshitaka; Hanayama, Ryohei; Nakayama, Suisei; Okihara, Shinichiro; Fujita, Kazuhisa; Sekina, Takashi; Sato, Nakahiro; Kurita, Takashi; Kawashima, Toshiyuki; Kan, Hirofumi; Komeda, Osamu; Nakamura, Naoki; Kondo, Takuya; Fujine, Manabu; Azuma, Hirozumi; Hioki, Tatsumi; Kakeno, Mitsutaka; Motohiro, Tomoyoshi; Nishimura, Yasuhiko; Sunahara, Atsushi; Sentoku, Yasuhiko; Miura, Eisuke; Kitagawa, Yoneyoshi

    2016-03-01

    We have developed the shadowgraph and interferometer with second-harmonic of heating pulses laser to observe target and plasma in highly-repetitive fusion reaction experiments. In the deuterated polystyrene ((C8D8)n double foil experiment, we confirm implosion plasma and plasma collision. In target injection experiment at a 1 Hz rate, we measure the position of the flying deuterated polystyrene beads at the moment of laser pulse illumination and observe the plasma generation by counter-illumination by 0.63 J, 800 nm, and 104 fs laser pulses.

  2. Reaching High-Yield Fusion with a Slow Plasma Liner Compressing a Magnetized Target

    SciTech Connect

    Ryutov, D D; Parks, P B

    2008-03-18

    Dynamics of the compression of a magnetized plasma target by a heavy liner made of partially ionized high high-Z material is discussed. A 'soft-landing' (shockless) mode of the liner deceleration is analyzed. Conclusion is drawn that such mode is possible for the liners whose thickness at the time of the first contact with the target is smaller than, roughly, 10% of the initial (un-compressed) target radius. A combination of the plasma liner with one or two glide cones allows for a direct access to the area near the center of the reactor chamber. One can then generate plasma target inside the plasma liner at the optimum time. The other advantage of the glide cones is that they can be used to deliver additional fuel to the center of the target near the point of a maximum compression and thereby increase the fusion yield.

  3. Distribution of Ionized Carbon during Simulated Plasma Disruption for the Isotropic Graphite Target

    NASA Astrophysics Data System (ADS)

    Sukegawa, Toshio; Okamoto, Koji; Madarame, Haruki

    The behavior of ionized carbon during the simulated plasma disruption is investigated with the Magneto-Plasma-Dynamic (MPD) Arc Jet. The temporal and spatial distributions of the ionized carbon were measured by emission spectroscopy. Distributions of CII and CIII were obtained. For the isotropic graphite target, the emission intensity increased as the target is exposed by the heat flux from plasma. Two consecutive peaks of intensity were observed at the point near the target surface. A simple model of redeposition and surface roughness could explain these phenomena.

  4. Equilibrium drives of the low and high field side n  =  2 plasma response and impact on global confinement

    NASA Astrophysics Data System (ADS)

    Paz-Soldan, C.; Logan, N. C.; Haskey, S. R.; Nazikian, R.; Strait, E. J.; Chen, X.; Ferraro, N. M.; King, J. D.; Lyons, B. C.; Park, J.-K.

    2016-05-01

    The nature of the multi-modal n  =  2 plasma response and its impact on global confinement is studied as a function of the axisymmetric equilibrium pressure, edge safety factor, collisionality, and L-versus H-mode conditions. Varying the relative phase (Δ {φ\\text{UL}} ) between upper and lower in-vessel coils demonstrates that different n  =  2 poloidal spectra preferentially excite different plasma responses. These different plasma response modes are preferentially detected on the tokamak high-field side (HFS) or low-field side (LFS) midplanes, have different radial extents, couple differently to the resonant surfaces, and have variable impacts on edge stability and global confinement. In all equilibrium conditions studied, the observed confinement degradation shares the same Δ {φ\\text{UL}} dependence as the coupling to the resonant surfaces given by both ideal (IPEC) and resistive (MARS-F) MHD computation. Varying the edge safety factor shifts the equilibrium field-line pitch and thus the Δ {φ\\text{UL}} dependence of both the global confinement and the n  =  2 magnetic response. As edge safety factor is varied, modeling finds that the HFS response (but not the LFS response), the resonant surface coupling, and the edge displacements near the X-point all share the same Δ {φ\\text{UL}} dependence. The LFS response magnitude is strongly sensitive to the core pressure and is insensitive to the collisionality and edge safety factor. This indicates that the LFS measurements are primarily sensitive to a pressure-driven kink-ballooning mode that couples to the core plasma. MHD modeling accurately reproduces these (and indeed all) LFS experimental trends and supports this interpretation. In contrast to the LFS, the HFS magnetic response and correlated global confinement impact is unchanged with plasma pressure, but is strongly reduced in high collisionality conditions in both H- and L-mode. This experimentally suggests the bootstrap

  5. Interaction between a high-kinetic-energy plasma jet and a target surface

    SciTech Connect

    Chen, Y.K.; Varghese, P.L.; Howell, J.R.

    1986-12-01

    A model is constructed to estimate the net energy deposited on a target wall bombarded by a plasma jet with gross kinetic energy much greater than its temperature and with density on the order of about 10/sup 19//cc (such as the plasma generated by a rail gun). Both one- and two-dimensional cases are examined to study the interactions between incident and reflected plasma ions. The results show that the reflected plasma plays an essential role in stopping the incident plasma energy over some small range of parameters.

  6. Final Report on Development of Optimized Field-Reversed Configuration Plasma Formation Techniques for Magnetized Target Fusion

    SciTech Connect

    Lynn, Alan

    2013-11-01

    The University of New Mexico (UNM) proposed a collaboration with Los Alamos National Laboratory (LANL) to develop and test methods for improved formation of field-reversed configuration (FRC) plasmas relevant to magnetized target fusion (MTF) energy research. MTF is an innovative approach for a relatively fast and cheap path to the production of fusion energy that utilizes magnetic confinement to assist in the compression of a hot plasma to thermonuclear conditions by an external driver. LANL is currently pursing demonstration of the MTF concept via compression of an FRC plasma by a metal liner z-pinch in conjunction with the Air Force Research Laboratory in Albuquerque, NM. A key physics issue for the FRC's ultimate success as an MTF target lies in the initial pre-ionization (PI) stage. The PI plasma sets the initial conditions from which the FRC is created. In particular, the PI formation process determines the amount of magnetic flux that can be trapped to form the FRC. A ringing theta pinch ionization (RTPI) technique, such as currently used by the FRX-L device at LANL, has the advantages of high ionization fraction, simplicity (since no additional coils are required), and does not require internal electrodes which can introduce impurities into the plasma. However RTPI has been shown to only trap 50% of the initial bias flux at best and imposes additional engineering constraints on the capacitor banks. The amount of trapped flux plays an important role in the FRC's final equilibrium, transport, and stability properties, and provides increased ohmic heating of the FRC through induced currents as the magnetic field decays. Increasing the trapped flux also provides the route to greatest potential gains in FRC lifetime, which is essential to provide enough time to translate and compress the FRC effectively. In conjunction with LANL we initially planned to develop and test a microwave break- down system to improve the initial PI plasma formation. The UNM team would

  7. Magnetic Fusion Energy Plasma Interactive and High Heat Flux Components: Volume 5, Technical assessment of critical issues in the steady state operation of fusion confinement devices

    SciTech Connect

    Not Available

    1988-01-01

    Critical issues for the steady state operation of plasma confinement devices exist in both the physics and technology fields of fusion research. Due to the wide range and number of these issues, this technical assessment has focused on the crucial issues associated with the plasma physics and the plasma interactive components. The document provides information on the problem areas that affect the design and operation of a steady state ETR or ITER type confinement device. It discusses both tokamaks and alternative concepts, and provides a survey of existing and planned confinement machines and laboratory facilities that can address the identified issues. A universal definition of steady state operation is difficult to obtain. From a physics point of view, steady state is generally achieved when the time derivatives approach zero and the operation time greatly exceeds the characteristic time constants of the device. Steady state operation for materials depends on whether thermal stress, creep, fatigue, radiation damage, or power removal are being discussed. For erosion issues, the fluence and availability of the machine for continuous operation are important, assuming that transient events such as disruptions do not limit the component lifetimes. The panel suggests, in general terms, that steady state requires plasma operation from 100 to 1000 seconds and an availability of more than a few percent, which is similar to the expectations for an ETR type device. The assessment of critical issues for steady state operation is divided into four sections: physics issues; technology issues; issues in alternative concepts; and devices and laboratory facilities that can address these problems.

  8. K-shell emission from 140 femtosecond laser-produced plasmas created from porous aluminum targets

    SciTech Connect

    Shepherd, R.; Price, D.; White, B.; Osterheld, A.; Walling, R.; Slaughter, D.; Stewart, R.; Gordan, S.

    1992-06-05

    The K-shell emission from flat and porous aluminum targets is used to infer the efficiency of creating a high temperature (>100eV), thermal plasma with 800 nm, 140 fs laser light. The K-shell emission from flat aluminum targets is fond to be significantly less than that of the porous targets, implying a lower temperature and less efficient coupling between the target and ultra-short pulse laser light.

  9. High energy density micro plasma bunch from multiple laser interaction with thin target

    SciTech Connect

    Xu, Han; Yu, Wei; Luan, S. X.; Xu, Z. Z.; Yu, M. Y.; Cai, H. B.; Zhou, C. T.; Yang, X. H.; Yin, Y.; Zhuo, H. B.; Wang, J. W.; Murakami, M.

    2014-01-13

    Three-dimensional particle-in-cell simulation is used to investigate radiation-pressure driven acceleration and compression of small solid-density plasma by intense laser pulses. It is found that multiple impacts by presently available short-pulse lasers on a small hemispheric shell target can create a long-living tiny quasineutral monoenergetic plasma bunch of very high energy density.

  10. The experimental plan for cryogenic layered target implosions on the National Ignition Facility - The inertial confinement approach to fusion

    SciTech Connect

    Edwards, M. J.; Lindl, J. D.; Spears, B. K.; Weber, S. V.; Atherton, L. J.; Bleuel, D. L.; Bradley, D. K.; Callahan, D. A.; Cerjan, C. J.; Clark, D; Collins, G. W.; Fair, J. E.; Fortner, R. J.; Glenzer, S. H.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Hatchett, S. P.; Izumi, N.; Jacoby, B.

    2011-05-15

    Ignition requires precisely controlled, high convergence implosions to assemble a dense shell of deuterium-tritium (DT) fuel with {rho}R>{approx}1 g/cm{sup 2} surrounding a 10 keV hot spot with {rho}R {approx} 0.3 g/cm{sup 2}. A working definition of ignition has been a yield of {approx}1 MJ. At this yield the {alpha}-particle energy deposited in the fuel would have been {approx}200 kJ, which is already {approx}10 x more than the kinetic energy of a typical implosion. The National Ignition Campaign includes low yield implosions with dudded fuel layers to study and optimize the hydrodynamic assembly of the fuel in a diagnostics rich environment. The fuel is a mixture of tritium-hydrogen-deuterium (THD) with a density equivalent to DT. The fraction of D can be adjusted to control the neutron yield. Yields of {approx}10{sup 14-15} 14 MeV (primary) neutrons are adequate to diagnose the hot spot as well as the dense fuel properties via down scattering of the primary neutrons. X-ray imaging diagnostics can function in this low yield environment providing additional information about the assembled fuel either by imaging the photons emitted by the hot central plasma, or by active probing of the dense shell by a separate high energy short pulse flash. The planned use of these targets and diagnostics to assess and optimize the assembly of the fuel and how this relates to the predicted performance of DT targets is described. It is found that a good predictor of DT target performance is the THD measurable parameter, Experimental Ignition Threshold Factor, ITFX {approx} Y x dsf {sup 2.3}, where Y is the measured neutron yield between 13 and 15 MeV, and dsf is the down scattered neutron fraction defined as the ratio of neutrons between 10 and 12 MeV and those between 13 and 15 MeV.

  11. Spectropolarimetry of blood plasma in optimal molecular targeted therapy

    NASA Astrophysics Data System (ADS)

    Voloshynska, Katerina; Ilashchuk, Tetjana; Yermolenko, Sergey

    2015-02-01

    The aim of the study was to establish objective parameters of the field of laser and incoherent radiation of different spectral ranges (UV, visible, IR) as a non-invasive optical method of interaction with different samples of biological tissues and fluids of patients to determine the dynamics of metabolic syndrome and choosing the best personal treatment. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5 - 25 microns) dry residue of plasma polarization and laser diagnostic technique of thin histological sections of biological tissues.

  12. Nail-like targets for laser plasma interaction experiments

    SciTech Connect

    Pasley, J; Wei, M; Shipton, E; Chen, S; Ma, T; Beg, F N; Alexander, N; Stephens, R B; MacPhee, A G; Hey, D; Pape, S L; Patel, P; Mackinnon, A J; Key, M H; Offermann, D; Link, A; Chowdhury, E; Van-Woerkom, L D; Freeman, R R

    2007-12-18

    The interaction of ultra-high power picosecond laser pulses with solid targets is of interest both for benchmarking the results of hybrid particle in cell (PIC) codes and also for applications to re-entrant cone guided fast ignition. We describe the construction of novel targets in which copper/titanium wires are formed into 'nail-like' objects by a process of melting and micromachining, so that energy can be reliably coupled to a 24 {micro}m diameter wire. An extreme-ultraviolet image of the interaction of the Titan laser with such a target is shown.

  13. Studies of plasma confinement in linear and RACETRACK mirror configurations. Progress report, January 1--October 31, 1986

    SciTech Connect

    Kuthi, A.; Wong, A.Y.

    1986-06-30

    This report discusses research on the following magnetic mirror configurations: Racetrack; ECRH generated plasmas; RF generated plasmas; potential structures; surface multipole fields, and lamex; hot electron physics; axial loss processes; and RF induced effects.

  14. A study of the methods for the production and confinement of high energy plasmas. [injection of dense plasma into long magnetic field

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.; Wang, P.

    1972-01-01

    The injection of dense plasmas into a B sub z long magnetic field from both ends of the field coil was investigated. Deflagration plasma guns and continuous flow Z-pinch are discussed along with the possibility of a continuous flow Z-pinch fusion reactor. The injection experiments are described with emphasis on the synchronization of the two plasma deflagration guns, the collision of the two plasma beams, and the determination of plasma density.

  15. Hydrogen plasma dynamics in the spherical theta pinch plasma target for heavy ion stripping

    SciTech Connect

    Loisch, G.; Jacoby, J.; Xu, G.; Blazevic, A.; Cihodariu-Ionita, B.

    2015-05-15

    Due to the superior ability of dense and highly ionised plasmas to ionise penetrating heavy ion beams to degrees beyond those reachable by common gas strippers, many experiments have been performed to find suitable plasma generators for this application. In the field of gas discharges, mainly z-pinch devices have been investigated so far, which are known to be limited by the nonlinear focusing effects of the plasma columns sustaining current and by electrode erosion. The spherical theta pinch has therefore been proposed as a substitution for the z-pinch, promising progress by inductive rather than capacitive coupling and displacement of the outer magnetic field by the dense, diamagnetic discharge plasma. As yet mainly experiments with argon/hydrogen mixture gas have been performed, which is not suitable for the application as a plasma stripper, this paper describes the first detailed analysis of the plasma parameters and dynamics of a hydrogen plasma created by the spherical theta pinch. These include the time integrated and time resolved electron density, the dynamics of the plasma in the discharge vessel, the comparison with the argon dominated plasma, and an outlook to reachable characteristics with similar devices.

  16. Absolute measurement of the total ion-drag force on a single plasma-confined microparticle at the void edge under microgravity conditions.

    PubMed

    Beckers, J; Trienekens, D J M; Kroesen, G M W

    2013-11-01

    We present an absolute measurement of the total ion-drag force on one single microparticle at the edge of the dust free region in low pressure complex plasmas: the void. In order to do so, the particle confinement position was monitored as a function of the gas pressure for two particle sizes under normal gravity conditions and under microgravity conditions during parabolic flights. At the border of the void, the ion-drag force on a particle with a radius of 4.90 μm appeared to be (3.6±0.3)×10(-12) N.

  17. On the Uniqueness of Solutions of a Nonlinear Elliptic Problem Arising in the Confinement of a Plasma in a Stellarator Device

    SciTech Connect

    Diaz, J. I.; Galiano, G.; Padial, J. F.

    1999-01-15

    We study the uniqueness of solutions of a semilinear elliptic problem obtained from an inverse formulation when the nonlinear terms of the equation are prescribed in a general class of real functions. The inverse problem arises in the modeling of the magnetic confinement of a plasma in a Stellarator device. The uniqueness proof relies on an L{sup {infinity}} -estimate on the solution of an auxiliary nonlocal problem formulated in terms of the relative rearrangement of a datum with respect to the solution.

  18. Physics of laser fusion. Vol. I. Theory of the coronal plasma in laser-fusion targets

    SciTech Connect

    Max, C.E.

    1981-12-01

    This monograph deals with the physics of the coronal region in laser fusion targets. The corona consists of hot plasma which has been evaporated from the initially solid target during laser heating. It is in the corona that the laser light is absorbed by the target, and the resulting thermal energy is conducted toward cold high-density regions, where ablation occurs. The topics to be discussed are theoretical mechanisms for laser light absorption and reflection, hot-electron production, and the physics of heat conduction in laser-produced plasmas. An accompanying monograph by H. Ahlstrom (Vol.II) reviews the facilities, diagnostics, and data from recent laser fusion experiments.

  19. Influence of Ambient Plasmas to the Field Dynamics of Laser Driven Mass-Limited Targets

    SciTech Connect

    Schnuerer, M.; Sokollik, T.; Steinke, S.; Nickles, P. V.; Sandner, W.; Toncian, T.; Amin, M.; Willi, O.; Andreev, A. A.

    2010-02-02

    Dilute plasmas surrounding mass-limited targets provide sufficient current for influencing strong fields, which are built up due to the interaction of an intense and ultrafast laser pulse. Such situation occurs, where evaporation of the target surface is present. The high-intensity laser pulse interacts with the quasi-isolated mass-limited target and the spatial wings of the intensity distribution account for ionization of the ambient plasma. A fast change of strong electrical fields following intense laser irradiation of water droplets (16 micron diameter) has been measured with proton imaging. An analytical model explains charge transport accounting for the observation.

  20. Local transport in Joint European Tokamak edge-localized, high-confinement mode plasmas with H, D, DT, and T isotopes

    NASA Astrophysics Data System (ADS)

    Budny, R. V.; Ernst, D. R.; Hahm, T. S.; McCune, D. C.; Christiansen, J. P.; Cordey, J. G.; Gowers, C. G.; Guenther, K.; Hawkes, N.; Jarvis, O. N.; Stubberfield, P. M.; Zastrow, K.-D.; Horton, L. D.; Saibene, G.; Sartori, R.; Thomsen, K.; von Hellermann, M. G.

    2000-12-01

    The edge-localized, high-confinement mode regime is of interest for future Tokamak reactors since high performance has been sustained for long durations. Experiments in the Joint European Tokamak [M. Keilhacker et al., Nuclear Fusion 39, 209 (1999)] have studied this regime using scans with the toroidal field and plasma current varied together in H, D, DT, and T isotopes. The local energy transport in more than fifty of these plasmas is analyzed, and empirical scaling relations are derived for energy transport coefficients during quasi-steady state conditions using dimensionless parameters. Neither the Bohm nor gyro-Bohm expressions give the shapes of the profiles. The scalings with β and ν* are in qualitative agreement with Ion Temperature Gradient theory.

  1. A target station for plasma exposure of neutron irradiated fusion material samples to reactor relevant conditions

    NASA Astrophysics Data System (ADS)

    Rapp, Juergen; Giuliano, Dominic; Ellis, Ronald; Howard, Richard; Lore, Jeremy; Lumsdaine, Arnold; Lessard, Timothy; McGinnis, William; Meitner, Steven; Owen, Larry; Varma, Venugopal

    2015-11-01

    The Material Plasma Exposure eXperiment (MPEX) is a device planned to address scientific and technological gaps for the development of viable plasma facing components for fusion reactor conditions (FNSF, DEMO). It will have to address the relevant plasma conditions in a reactor divertor (electron density, electron temperature, ion fluxes) and it needs to be able to expose a-priori neutron irradiated samples. A pre design of a target station able to handle activated materials will be presented. This includes detailed MCNP as well as SCALE and MAVRIC calculations for all potential plasma-facing materials to estimate dose rates. Details on the remote handling schemes for the material samples will be presented. 2 point modeling of the linear plasma transport has been used to scope out the parameter range of the anticipated power fluxes to the target. This has been used to design the cooling capability of the target. The operational conditions of surface temperatures, plasma conditions, and oblique angle of incidence of magnetic field to target surface will be discussed. ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC-05-00OR22725.

  2. Analysis of Data From Z-Pinch MTF Target-Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Taccetti, J. M.; Wysocki, F. J.; Benage, J. F.; Idzorek, G.; Oona, H.; Kirkpatrick, R. C.; Lindemuth, I. R.; Sheehey, P. T.

    1999-11-01

    Magnetized Target Fusion (MTF) target-plasma experiments have been performed at Los Alamos National Laboratory Colt facility for roughly three years(F. J. Wysocki et al., Digest of Technical Papers for the 11th IEEE International Pulsed Power Conference, Baltimore, Maryland, June 29 to July 2, 1997, G. Cooperstein and I. Vitkovitsky editors, p. 1393.). The capacitor bank has a max output voltage of 120 kV, max energy store of 0.25 MJ, and can deliver at least 2 MA of current to a load in 2.5 μs. The MTF target plasma is generated by driving a z-directed current through a plasma which is contained by a 2 cm radius by 2 cm high cylindrical metal wall. The initial mass for the target plasma comes from either a static uniform fill of hydrogen or deuterium gas, or from a polyethylene fiber mounted along the central axis. The diagnostic set includes an array of 12 B-dot probes, optical framing camera, gated OMA visible spectrometer, time-resolved monochrometer, filtered silicon photodiodes, neutron yield, and a laser interferometer. Measurements of the plasma temperature and impurity content obtained to date with a transmission grating spectrometer will also be presented. The data obtained allows an assessment of the plasma temperature, density, magnetization, and decay time.

  3. Changes in core electron temperature fluctuations across the ohmic energy confinement transition in Alcator C-Mod plasmas

    NASA Astrophysics Data System (ADS)

    Sung, C.; White, A. E.; Howard, N. T.; Oi, C. Y.; Rice, J. E.; Gao, C.; Ennever, P.; Porkolab, M.; Parra, F.; Mikkelsen, D.; Ernst, D.; Walk, J.; Hughes, J. W.; Irby, J.; Kasten, C.; Hubbard, A. E.; Greenwald, M. J.; the Alcator C-Mod Team

    2013-08-01

    The first measurements of long wavelength (kyρs < 0.3) electron temperature fluctuations in Alcator C-Mod made with a new correlation electron cyclotron emission diagnostic support a long-standing hypothesis regarding the confinement transition from linear ohmic confinement (LOC) to saturated ohmic confinement (SOC). Electron temperature fluctuations decrease significantly (∼40%) crossing from LOC to SOC, consistent with a change from trapped electron mode (TEM) turbulence domination to ion temperature gradient (ITG) turbulence as the density is increased. Linear stability analysis performed with the GYRO code (Candy and Waltz 2003 J. Comput. Phys. 186 545) shows that TEMs are dominant for long wavelength turbulence in the LOC regime and ITG modes are dominant in the SOC regime at the radial location (ρ ∼ 0.8) where the changes in electron temperature fluctuations are measured. In contrast, deeper in the core (ρ < 0.8), linear stability analysis indicates that ITG modes remain dominant across the LOC/SOC transition. This radial variation suggests that the robust global changes in confinement of energy and momentum occurring across the LOC/SOC transition are correlated to local changes in the dominant turbulent mode near the edge.

  4. Plasma Processing of Functional Thin Films by Sputtering Deposition Using Metal-Based Powder Target

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hiroharu; Ohshima, Tamiko; Ihara, Takeshi; Arafune, Kento; Taniyama, Daichi; Yagyu, Yoshihito; Suda, Yoshiaki

    2013-11-01

    Titanium-based functional thin films were prepared by a sputtering deposition method using a metal powder target, and the electron density and temperature of the processing plasma were investigated. The electron density of the plasma, measured by a probe method, when using a powder target was higher than that when using a bulk target. The deposition rate when using a powder target was also higher than that in the case of a bulk target. These results may be due to the net-cathode area of the powder target being larger than that of the bulk target. X-ray photoelectron spectroscopy, X-ray diffraction measurements, and atomic force microscopy images of the films prepared using the Ti powder target indicated nearly the same properties as those of films prepared using a Ti bulk target, and the prepared films are oxide. These results suggest that TiO2 thin films can be prepared using a Ti powder target and that the quality is almost the same as those of films prepared using a Ti bulk target.

  5. Targeting the cancer cell cycle by cold atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Volotskova, O.; Hawley, T. S.; Stepp, M. A.; Keidar, M.

    2012-09-01

    Cold atmospheric plasma (CAP), a technology based on quasi-neutral ionized gas at low temperatures, is currently being evaluated as a new highly selective alternative addition to existing cancer therapies. Here, we present a first attempt to identify the mechanism of CAP action. CAP induced a robust ~2-fold G2/M increase in two different types of cancer cells with different degrees of tumorigenicity. We hypothesize that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. The expression of γH2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle. Together with a significant decrease in EdU-incorporation after CAP, these data suggest that tumorigenic cancer cells are more susceptible to CAP treatment.

  6. Targeted Lipid Profiling Discovers Plasma Biomarkers of Acute Brain Injury

    PubMed Central

    Sheth, Sunil A.; Iavarone, Anthony T.; Liebeskind, David S.; Won, Seok Joon; Swanson, Raymond A.

    2015-01-01

    Prior efforts to identify a blood biomarker of brain injury have relied almost exclusively on proteins; however their low levels at early time points and poor correlation with injury severity have been limiting. Lipids, on the other hand, are the most abundant molecules in the brain and readily cross the blood-brain barrier. We previously showed that certain sphingolipid (SL) species are highly specific to the brain. Here we examined the feasibility of using SLs as biomarkers for acute brain injury. A rat model of traumatic brain injury (TBI) and a mouse model of stroke were used to identify candidate SL species though our mass-spectrometry based lipid profiling approach. Plasma samples collected after TBI in the rat showed large increases in many circulating SLs following injury, and larger lesions produced proportionately larger increases. Plasma samples collected 24 hours after stroke in mice similarly revealed a large increase in many SLs. We constructed an SL score (sum of the two SL species showing the largest relative increases in the mouse stroke model) and then evaluated the diagnostic value of this score on a small sample of patients (n = 14) who presented with acute stroke symptoms. Patients with true stroke had significantly higher SL scores than patients found to have non-stroke causes of their symptoms. The SL score correlated with the volume of ischemic brain tissue. These results demonstrate the feasibility of using lipid biomarkers to diagnose brain injury. Future studies will be needed to further characterize the diagnostic utility of this approach and to transition to an assay method applicable to clinical settings. PMID:26076478

  7. Streaked optical pyrometry of ion heated compound targets in the study of plasma mix at high density interfaces

    NASA Astrophysics Data System (ADS)

    Dyer, Gilliss; Roycroft, Rebecca; Wagner, Craig; Bernstein, Aaron; Ditmire, Todd; Hegelich, B. Manuel; Albright, Brian; Fernández, Juan; Bang, Woosuk; Bradley, Paul; Gautier, D. Cort; Hamilton, Christopher; Palaniyappan, Sasi; Santiago Cordoba, Miguel; Vold, Erik; Lin, Yin

    2015-11-01

    The interaction and mixing of different species of plasma at high energy density is of fundamental interest for HED physics and relevant to inertial confinement fusion. An ongoing campaign is underway at the Trident laser facility to study the dynamics at the interface of high and low atomic number materials under warm dense matter conditions. The experiments utilize laser-accelerated ions, such as aluminum, to flash heat solid targets to temperatures >1 eV. We report on streaked pyrometry measurements made in a recent experimental run, which shed light on the dynamics of heating induced in various target materials by these ion sources. Timescale as well as spatial extent of the heating can vary greatly depending on the dominant ion species and spectra. This work was supported by NNSA cooperative agreement DE-NA0002008 and the Los Alamos National Laboratory Directed Research and Development Program under the auspices of the U.S. DOE NNSAS, LLC, Los Alamos National Laboratory under Contract No. DE-AC52-06.

  8. Electron Density and Two-Channel Neutron Emission Measurements in Steady-State Spherical Inertial-Electrostatically Confined Plasmas, with Review of the 1-D Kinetic Model

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Hrbud, Ivana

    2004-01-01

    Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the 1-D Poisson equation for EC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with non-fusing hydrogen-1. The deuterium rates are consistent with predictions from the model.

  9. Direct observation of transition to electron Bernstein waves from electromagnetic mode by three mode-conversion scenarios in the dipole confinement torus plasma

    NASA Astrophysics Data System (ADS)

    Uchijima, K.; Takemoto, T.; Morikawa, J.; Ogawa, Y.

    2015-06-01

    Direct measurement experiments on the mode conversion to the electron Bernstein wave (EBW) have been conducted in dipole confinement torus plasmas for three excitation scenarios; i.e. perpendicular injections of an eXtraordinary mode (X-mode) from the low- and high-magnetic-field sides, and the oblique injection of an Ordinary mode (O-mode) from the low-magnetic-field side. By inserting probe antennas into plasmas, wave propagation has been directly measured. At plasma conditions for the EBW excitation, several characteristics which indicate the mode conversion to the EBWs have been observed; i.e. a short wavelength wave, an electrostatic and longitudinal mode, backward propagation at the upper hybrid resonance (UHR) region. Meanwhile, the wavelengths experimentally observed might be slightly longer than those of theoretical prediction. In the case of the oblique injection of the O-mode, it has been identified that the window of the injection angle for the excitation of the EBW would be quite limited, and the optimum angle seems to be roughly in agreement with theory. These experimental results might support that the electromagnetic waves injected outside of torus plasmas reach to the UHR region and convert wave characteristics to the EBWs for three excitation scenarios.

  10. Propagation velocities of laser-produced plasmas from copper wire targets and water droplets

    NASA Technical Reports Server (NTRS)

    Song, Kyo-Dong; Alexander, Dennis R.

    1994-01-01

    Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

  11. Enhancement of the maximum proton energy by funnel-geometry target in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Yang, Peng; Fan, Dapeng; Li, Yuxiao

    2016-09-01

    Enhancement of the maximum proton energy using a funnel-geometry target is demonstrated through particle simulations of laser-plasma interactions. When an intense short-pulse laser illuminate a thin foil target, the foil electrons are pushed by the laser ponderomotive force, and then form an electron cloud at the target rear surface. The electron cloud generates a strong electrostatic field, which accelerates the protons to high energies. If there is a hole in the rear of target, the shape of the electron cloud and the distribution of the protons will be affected by the protuberant part of the hole. In this paper, a funnel-geometry target is proposed to improve the maximum proton energy. Using particle-in-cell 2-dimensional simulations, the transverse electric field generated by the side wall of four different holes are calculated, and protons inside holes are restricted to specific shapes by these field. In the funnel-geometry target, more protons are restricted near the center of the longitudinal accelerating electric field, thus protons experiencing longer accelerating time and distance in the sheath field compared with that in a traditional cylinder hole target. Accordingly, more and higher energy protons are produced from the funnel-geometry target. The maximum proton energy is improved by about 4 MeV compared with a traditional cylinder-shaped hole target. The funnel-geometry target serves as a new method to improve the maximum proton energy in laser-plasma interactions.

  12. Morphological and structural effects on tungsten targets produced by fusion plasma pulses from a table top plasma focus

    NASA Astrophysics Data System (ADS)

    Inestrosa-Izurieta, M. J.; Ramos-Moore, E.; Soto, L.

    2015-09-01

    A table top plasma focus device operating at hundreds of joules was used to simulate an equivalent damage factor than the obtained on the divertor in tokamak experiments. Using the ejected plasma produced after the pinch disruptions, the effects on tungsten targets from 50 cumulative plasma shocks with power fluxes per shot between 2.6 and 9200 kW cm-2 and with a duration time in the order of tens of nanoseconds (damage factor in the order of 100-103 (W cm-2)s1/2) were studied. Morphological analysis shows an increasing appearance of cracked surfaces with holes, fissures and defects, suggesting a potential progression of stress effects and a fast heat load that melts the surface, ending in thermal contractions that recrystallize the surface of the target. A structural analysis demonstrates a compressive stress development and suggests that part of the energy is released in the melting of the surface in case of a plasma shock with a power flux of 9.2 MW cm-2, 75 ns duration pulse, 2.5   ×   103 (W cm-2)s1/2 damage factor. How to increase the damage factor by one order of magnitude up to the expected value from type I ELMs on the ITER divertor, i.e. 104 (W cm-2)s1/2 is discussed.

  13. Detailed energy distributions in laser-produced plasmas of solid gold and foam gold planar targets

    SciTech Connect

    Dong, Yunsong; Zhang, Lu; Yang, Jiamin; Shang, Wanli

    2013-12-15

    Foam gold was proposed to increase the laser to x-ray conversion efficiency due to its important applications. To understand the mechanism of x-ray enhancement, the detailed energy distributions and plasma profiles for laser-irradiated solid gold and foam gold targets were studied comparatively by hydrodynamic simulations using the code Multi-1D. It is confirmed that the radiation heat wave is subsonic for the normal solid gold target, while supersonic for the foam gold target. The shock wave, which is behind the supersonic radiation heat wave for the foam gold target, generates a plasma temperature gradient with high temperature near the shock wave front to produce an additional net outward radiation for enhancement of the x-ray emission. Much larger inward plasma velocity is also driven by the shock wave as an initial plasma velocity for the laser deposition and electron thermal conduct zone, which decreases the expanding plasma kinetic energy loss and helps to increase the x-ray radiation.

  14. High-resolution time-resolved x-ray microscope for inertial confinement fusion (ICF) target dynamics experiments

    SciTech Connect

    Ellis, R.J.; Kilkenny, J.D.; Levesque, R.A.; Phillion, D.W.; Deane, D.J.

    1987-10-01

    A versatile x-ray microscope diagnostic has been built to perform target dynamics experiments on the Nova Ten Beam target irradiation facility. This system is based on Wolter's axisymmetric focusing scheme. An alignment system is described which provides for both quick and accurate alignment of the x-ray optic. Results are presented showing the system resolution and accuracy of alignment. Images from target dynamics experiments are also presented. 9 refs.

  15. Effect of the electronic structure of target atoms on the emission continuum of laser plasma

    SciTech Connect

    Kask, Nikolai E; Michurin, Sergei V; Fedorov, Gennadii M

    2004-06-30

    The low-temperature laser plasma at the surface of metal targets is experimentally investigated. Continuous spectra emitted from a laser plume are found to be similar for targets consisting of the elements of the same subgroup of the Mendeleev periodic table. The similarity manifests itself both in the dependence of the emission intensity on the external pressure and in the structure of absorption bands related to a fine-dispersed phase existing in the peripheral regions of the plume. (interaction of laser radiation with matter. laser plasma)

  16. Nonlinear surface plasma wave induced target normal sheath acceleration of protons

    SciTech Connect

    Liu, C. S.; Tripathi, V. K. Shao, Xi; Liu, T. C.

    2015-02-15

    The mode structure of a large amplitude surface plasma wave (SPW) over a vacuum–plasma interface, including relativistic and ponderomotive nonlinearities, is deduced. It is shown that the SPW excited by a p-polarized laser on a rippled thin foil target can have larger amplitude than the transmitted laser amplitude and cause stronger target normal sheath acceleration of protons as reported in a recent experiment. Substantial enhancement in proton number also occurs due to the larger surface area covered by the SPW.

  17. Laser-plasma debris from a rotating cryogenic-solid-Xe target

    SciTech Connect

    Amano, Sho; Inaoka, Yutaka; Hiraishi, Hiroki; Miyamoto, Shuji; Mochizuki, Takayasu

    2010-02-15

    We investigate the characteristics of laser plasma debris that is responsible for damaging optics. The debris is composed of fast ions, neutral particles, and fragments, and originates from a solid Xe target on a rotating drum that we developed as an extreme ultraviolet (EUV) source. The ice fragments appear to be a problem most notably with solid Xe targets; however, we find that the damage induced by Xe ice fragments can be avoided by simply reducing the laser pulse energy. We find the number of fast neutral particles to be an order of magnitude less than the number of ions, and we clarify that the plasma debris is primarily composed of fast ions. In addition, we find that the number of fast ions having a few dozen keV of energy decreases when using the rotating target compared with the rest target. We attribute this to a gas curtain effect from the Xe gas localized at the rotating target surface. We estimate the sputtering rate of the Mo/Si mirror, which is caused primarily by the fast ions, to be 104 nm/1x10{sup 6} shots at 190 mm from the source plasma and at an 11.25 deg. angle from the incident laser beam. Up to the 1x10{sup 6} shots exposure, remarkable degradation of the mirror reflectivity is not observed though the sputtering damages the mirror. Mitigation of the ions by using gas and/or magnetic fields will further improve the mirror lifetime. By comparing with a liquid jet Xe target, we conclude that the sputtering rate per conversion efficiency when using the solid Xe targets on the rotating drum is the same as that when using the liquid Xe targets. The high conversion efficiency of 0.9% in the rotating drum solid Xe target makes this technique useful for developing laser plasma EUV sources.

  18. Fast ignition when heating the central part of an inertial confinement fusion target by an ion beam

    SciTech Connect

    Gus’kov, S. Yu.; Zmitrenko, N. V.; Il’in, D. V.; Sherman, V. E.

    2014-11-15

    We investigate the ignition and burning of a precompressed laser fusion target when it is rapidly heated by an ion beam with the formation of a temperature peak in the central part of the target. We present the results of our comprehensive numerical simulations of the problem that include the following components: (1) the target compression under the action of a profiled laser pulse, (2) the heating of the compressed target with spatially nonuniform density and temperature distributions by a beam of high-energy ions, and (3) the burning of the target with the initial spatial density distribution formed at the instant of maximum target compression and the initial spatial temperature distribution formed as a result of the compressed-target heating by an ion beam. The dependences of the threshold energies of the igniting ion beam and the thermonuclear gain on the width of the Gaussian beam ion energy spectrum have been established. The peculiarities of fast ignition by an ion beam related to the spatial distribution of parameters for the target precompressed by a laser pulse are discussed.

  19. Cylindrically confined pair-ion-electron and pair-ion plasmas having axial sheared flow and radial gradients

    SciTech Connect

    Batool, Nazia; Saleem, H.

    2013-10-15

    The linear and nonlinear dynamics of pair-ion (PI) and pair-ion-electron plasmas (PIE) have been investigated in a cylindrical geometry with a sheared plasma flow along the axial direction having radial dependence. The coupled linear dispersion relation of low frequency electrostatic waves has been presented taking into account the Guassian profile of density and linear gradient of sheared flow. It is pointed out that the quasi-neutral cold inhomogeneous pure pair ion plasma supports only the obliquely propagating convective cell mode. The linear dispersion relation of this mode has been solved using boundary conditions. The nonlinear structures in the form of vortices formed by different waves have been discussed in PI and PIE plasmas.

  20. Plasma barodiffusion in inertial-confinement-fusion implosions: application to observed yield anomalies in thermonuclear fuel mixtures.

    PubMed

    Amendt, Peter; Landen, O L; Robey, H F; Li, C K; Petrasso, R D

    2010-09-10

    The observation of large, self-generated electric fields (≥10(9)  V/m) in imploding capsules using proton radiography has been reported [C. K. Li, Phys. Rev. Lett. 100, 225001 (2008)]. A model of pressure gradient-driven diffusion in a plasma with self-generated electric fields is developed and applied to reported neutron yield deficits for equimolar D3He [J. R. Rygg, Phys. Plasmas 13, 052702 (2006)] and (DT)3He [H. W. Herrmann, Phys. Plasmas 16, 056312 (2009)] fuel mixtures and Ar-doped deuterium fuels [J. D. Lindl, Phys. Plasmas 11, 339 (2004)]. The observed anomalies are explained as a mild loss of deuterium nuclei near capsule center arising from shock-driven diffusion in the high-field limit.

  1. Production of field-reversed mirror plasma with a coaxial plasma gun

    DOEpatents

    Hartman, C.W.; Shearer, J.W.

    The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode.

  2. Production of field-reversed mirror plasma with a coaxial plasma gun

    DOEpatents

    Hartman, Charles W.; Shearer, James W.

    1982-01-01

    The use of a coaxial plasma gun to produce a plasma ring which is directed into a magnetic field so as to form a field-reversed plasma confined in a magnetic mirror. Plasma thus produced may be used as a target for subsequent neutral beam injection or other similarly produced and projected plasma rings or for direct fusion energy release in a pulsed mode.

  3. AINSE Plasma Science and Technology Conference and Elizabeth and Frederick White Workshop on Fundamental Problems in the Physics of Magnetically Confined Plasmas: Conference handbook

    NASA Astrophysics Data System (ADS)

    The handbook contains abstracts of papers and posters presented at the conference. The main topics relate to plasma physics and fusion, plasma processing and uses as well as specific fusion devices and experiments. Eighty-four out of ninety-two presentations were considered to be in the INIS subject scope and have been separately indexed.

  4. Inertial confinement fusion target component fabrication and technology development support. Annual report, October 1, 1996--September 30, 1997

    SciTech Connect

    Gibson, J.

    1998-03-01

    This report documents the technical activities of the period October 1, 1996 through September 30, 1997. During this period, GA and their partner Schafer Corporation were assigned 13 formal tasks in support of the ICF program and its five laboratories. A portion of the effort on these tasks included providing direct {open_quotes}Onsite Support{close_quotes} at Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), and Sandia National Laboratory Albuquerque (SNLA). Over 700 gold-plated hohlraum mandrels were fabricated and delivered to LLNL, LANL and SNLA. More than 1600 glass and plastic target capsules were produced for LLNL, LANL, SNLA and University of Rochester/Laboratory for Laser Energetics (UR/LLE). Nearly 2000 various target foils and films were delivered for Naval Research Lab (NRL) and UR/LLE in FY97. This report describes these target fabrication activities and the target fabrication and characterization development activities that made the deliveries possible. The ICF program is anticipating experiments at the OMEGA laser and the National Ignition Facility (NIF) which will require targets containing cryogenic layered D{sub 2} or deuterium-tritium (DT) fuel. This project is part of the National Cryogenic Target Program and support experiments at LLNL and LANL to generate and characterize cryogenic layers for these targets. During FY97, significant progress was made in the design and component testing of the OMEGA Cryogenic Target System that will field cryogenic targets on OMEGA. This included major design changes, reduction in equipment, and process simplifications. This report summarizes and documents the technical progress made on these tasks.

  5. Direct asymmetry measurement of temperature and density spatial distributions in inertial confinement fusion plasmas from pinhole space-resolved spectra

    SciTech Connect

    Nagayama, T.; Mancini, R. C.; Florido, R.; Mayes, D.; Tommasini, R.; Koch, J. A.; Delettrez, J. A.; Regan, S. P.; Smalyuk, V. A.

    2014-05-15

    Two-dimensional space-resolved temperature and density images of an inertial confinement fusion (ICF) implosion core have been diagnosed for the first time. Argon-doped, direct-drive ICF experiments were performed at the Omega Laser Facility and a collection of two-dimensional space-resolved spectra were obtained from an array of gated, spectrally resolved pinhole images recorded by a multi-monochromatic x-ray imager. Detailed spectral analysis revealed asymmetries of the core not just in shape and size but in the temperature and density spatial distributions, thus characterizing the core with an unprecedented level of detail.

  6. Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

    NASA Astrophysics Data System (ADS)

    Calandrini, Eugenio; Venanzi, Tommaso; Appugliese, Felice; Badioli, Michela; Giliberti, Valeria; Baldassarre, Leonetta; Biagioni, Paolo; De Angelis, Francesco; Klesse, Wolfgang M.; Scappucci, Giordano; Ortolani, Michele

    2016-09-01

    We study plasmonic nanoantennas for molecular sensing in the mid-infrared made of heavily doped germanium, epitaxially grown with a bottom-up doping process and featuring free carrier density in excess of 1020 cm-3. The dielectric function of the 250 nm thick germanium film is determined, and bow-tie antennas are designed, fabricated, and embedded in a polymer. By using a near-field photoexpansion mapping technique at λ = 5.8 μm, we demonstrate the existence in the antenna gap of an electromagnetic energy density hotspot of diameter below 100 nm and confinement volume 105 times smaller than λ3.

  7. Fusion, magnetic confinement

    SciTech Connect

    Berk, H.L.

    1992-08-06

    An overview is presented of the principles of magnetic confinement of plasmas for the purpose of achieving controlled fusion conditions. Sec. 1 discusses the different nuclear fusion reactions which can be exploited in prospective fusion reactors and explains why special technologies need to be developed for the supply of tritium or {sup 3}He, the probable fuels. In Sec. 2 the Lawson condition, a criterion that is a measure of the quality of confinement relative to achieving fusion conditions, is explained. In Sec. 3 fluid equations are used to describe plasma confinement. Specific confinement configurations are considered. In Sec. 4 the orbits of particle sin magneti and electric fields are discussed. In Sec. 5 stability considerations are discussed. It is noted that confinement systems usually need to satisfy stability constraints imposed by ideal magnetohydrodynamic (MHD) theory. The paper culminates with a summary of experimental progress in magnetic confinement. Present experiments in tokamaks have reached the point that the conditions necessary to achieve fusion are being satisfied.

  8. Laser induced plasma on copper target, a non-equilibrium model

    SciTech Connect

    Oumeziane, Amina Ait Liani, Bachir; Parisse, Jean-Denis

    2014-02-15

    The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation.

  9. Binding and Fusion of Extracellular Vesicles to the Plasma Membrane of Their Cell Targets

    PubMed Central

    Prada, Ilaria; Meldolesi, Jacopo

    2016-01-01

    Exosomes and ectosomes, extracellular vesicles of two types generated by all cells at multivesicular bodies and the plasma membrane, respectively, play critical roles in physiology and pathology. A key mechanism of their function, analogous for both types of vesicles, is the fusion of their membrane to the plasma membrane of specific target cells, followed by discharge to the cytoplasm of their luminal cargo containing proteins, RNAs, and DNA. Here we summarize the present knowledge about the interactions, binding and fusions of vesicles with the cell plasma membrane. The sequence initiates with dynamic interactions, during which vesicles roll over the plasma membrane, followed by the binding of specific membrane proteins to their cell receptors. Membrane binding is then converted rapidly into fusion by mechanisms analogous to those of retroviruses. Specifically, proteins of the extracellular vesicle membranes are structurally rearranged, and their hydrophobic sequences insert into the target cell plasma membrane which undergoes lipid reorganization, protein restructuring and membrane dimpling. Single fusions are not the only process of vesicle/cell interactions. Upon intracellular reassembly of their luminal cargoes, vesicles can be regenerated, released and fused horizontally to other target cells. Fusions of extracellular vesicles are relevant also for specific therapy processes, now intensely investigated. PMID:27517914

  10. The influence of target irradiation conditions on the parameters of laser-produced plasma jets

    NASA Astrophysics Data System (ADS)

    Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-03-01

    Recent experimental results demonstrate that the forming of plasma jets is a fundamental process accompanying the laser-produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, 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)]. with the third harmonic beam of the pulse duration of 250ps. The beam energies varied in the range of 13-160J. The planar massive targets used in the experiment were made of copper. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were produced in the whole range of the laser energy used. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

  11. The influence of target irradiation conditions on the parameters of laser-produced plasma jets

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-03-15

    Recent experimental results demonstrate that the forming of plasma jets is a fundamental process accompanying the laser-produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, 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)]. with the third harmonic beam of the pulse duration of 250 ps. The beam energies varied in the range of 13-160 J. The planar massive targets used in the experiment were made of copper. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were produced in the whole range of the laser energy used. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

  12. Binding and Fusion of Extracellular Vesicles to the Plasma Membrane of Their Cell Targets.

    PubMed

    Prada, Ilaria; Meldolesi, Jacopo

    2016-01-01

    Exosomes and ectosomes, extracellular vesicles of two types generated by all cells at multivesicular bodies and the plasma membrane, respectively, play critical roles in physiology and pathology. A key mechanism of their function, analogous for both types of vesicles, is the fusion of their membrane to the plasma membrane of specific target cells, followed by discharge to the cytoplasm of their luminal cargo containing proteins, RNAs, and DNA. Here we summarize the present knowledge about the interactions, binding and fusions of vesicles with the cell plasma membrane. The sequence initiates with dynamic interactions, during which vesicles roll over the plasma membrane, followed by the binding of specific membrane proteins to their cell receptors. Membrane binding is then converted rapidly into fusion by mechanisms analogous to those of retroviruses. Specifically, proteins of the extracellular vesicle membranes are structurally rearranged, and their hydrophobic sequences insert into the target cell plasma membrane which undergoes lipid reorganization, protein restructuring and membrane dimpling. Single fusions are not the only process of vesicle/cell interactions. Upon intracellular reassembly of their luminal cargoes, vesicles can be regenerated, released and fused horizontally to other target cells. Fusions of extracellular vesicles are relevant also for specific therapy processes, now intensely investigated. PMID:27517914

  13. A novel technique for single-shot energy-resolved 2D x-ray imaging of plasmas relevant for the inertial confinement fusion

    SciTech Connect

    Labate, L.; Koester, P.; Levato, T.; Gizzi, L. A.

    2012-10-15

    A novel x-ray diagnostic of laser-fusion plasmas is described, allowing 2D monochromatic images of hot, dense plasmas to be obtained in any x-ray photon energy range, over a large domain, on a single-shot basis. The device (named energy-encoded pinhole camera) is based upon the use of an array of many pinholes coupled to a large area CCD camera operating in the single-photon mode. The available x-ray spectral domain is only limited by the quantum efficiency of scientific-grade x-ray CCD cameras, thus extending from a few keV up to a few tens of keV. Spectral 2D images of the emitting plasma can be obtained at any x-ray photon energy provided that a sufficient number of photons had been collected at the desired energy. Results from recent inertial confinement fusion related experiments will be reported in order to detail the new diagnostic.

  14. Developments and fabrication of laser targets used to prepare inertial confinement fusion (ICF) experiments on CEA Laser ``M'egajoule'' (LMJ) facility

    NASA Astrophysics Data System (ADS)

    Bednarczyk, Sophie; Durut, Frédéric; Reneaume, Benoît; Théobald, Marc; Casner, Alexis; Tassin, Véronique; Monteil, Marie-Christine; Galmich, Didier

    2008-11-01

    A micro materials and technologies research program has started in France since 10 years to develop a very complex cryogenic target to reach the combustion of a deuterium tritium mixture, by indirect drive on the CEA Laser ``M'egajoule'' (LMJ) facility. This mixture is contained by an amorphous hydrogenated carbon (a-C:H or CHx) doped with germanium capsule placed in the center of a hohlraum. This research program involves CEA scientists, engineers and technicians united to realize specific targets for carrying out laser plasma experiments on the CEA LIL ``Ligne d'Int'egration Laser'' or OMEGA-UPGRADE facilities. To achieve the production of such specific targets different technologies are successively used (coating, precision machining, laser machining, characterizations, assembling, etc). This article presents an illustration of these microtechnology realizations through particular complex laser targets for hydrodynamic, or parametric instabilities studies and for symmetry experimental effects studies on fusion burn.

  15. Fabrication and testing of gas-filled targets for large-scale plasma experiments on nova

    SciTech Connect

    Stone, G.F.; Rivers, C.J.; Spragge, M.R.; Wallace, R.J.

    1996-06-01

    The proposed next-generation ICF facility, the National Ignition Facility (NIF) is designed to produce energy gain from x-ray heated {open_quotes}indirect-drive{close_quotes} fuel capsules. For indirect-drive targets, laser light heats the inside of the Au hohlraum wall and produces x rays which in turn heat and implode the capsule to produce fusion conditions in the fuel. Unlike Nova targets, in NIF-scale targets laser light will propagate through several millimeters of gas, producing a plasma, before impinging upon the Au hohlraum wall. The purpose of the gas-produced plasma is to provide sufficient pressure to keep the radiating Au surface from expanding excessively into the hohlraum cavity. Excessive expansion of the Au wall interacts with the laser pulse and degrades the drive symmetry of the capsule implosion. The authors have begun an experimental campaign on the Nova laser to study the effect of hohlraum gas on both laser-plasma interaction and implosion symmetry. In their current NIF target design, the calculated plasma electron temperature is T{sub e} {approx} 3 keV and the electron density is N{sub e} {approx} 10{sup 21}cm{sup {minus}3}.

  16. Video Views and Reviews: Golgi Export, Targeting, and Plasma Membrane Caveolae

    ERIC Educational Resources Information Center

    Watters, Christopher

    2004-01-01

    In this article, the author reviews videos from "Molecular Biology of the Cell (MBC)" depicting various aspects of plasma membrane (PM) dynamics, including the targeting of newly synthesized components and the organization of those PM invaginations called caveolae. The papers accompanying these videos describe, respectively, the constitutive…

  17. Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

    DOEpatents

    Kublak, Glenn D.; Richardson, Martin C. (CREOL

    1996-01-01

    Method and apparatus for producing extreme ultra violet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10.sup.11 -10.sup.12 watts/cm.sup.2) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10-30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle.

  18. Cluster beam targets for laser plasma extreme ultraviolet and soft x-ray sources

    DOEpatents

    Kublak, G.D.; Richardson, M.C.

    1996-11-19

    Method and apparatus for producing extreme ultraviolet (EUV) and soft x-ray radiation from an ultra-low debris plasma source are disclosed. Targets are produced by the free jet expansion of various gases through a temperature controlled nozzle to form molecular clusters. These target clusters are subsequently irradiated with commercially available lasers of moderate intensity (10{sup 11}--10{sup 12} watts/cm{sup 2}) to produce a plasma radiating in the region of 0.5 to 100 nanometers. By appropriate adjustment of the experimental conditions the laser focus can be moved 10--30 mm from the nozzle thereby eliminating debris produced by plasma erosion of the nozzle. 5 figs.

  19. The intracellular carboxyl terminal domain of Vangl proteins contains plasma membrane targeting signals

    PubMed Central

    Iliescu, Alexandra; Gros, Philippe

    2014-01-01

    Vangl1 and Vangl2 are integral membrane proteins that play a critical role in establishing planar cell polarity (PCP) in epithelial cells and are required for convergent extension (CE) movements during embryogenesis. Their proper targeting to the plasma membrane (PM) is required for function. We created discrete deletions at the amino and carboxy termini of Vangl1 and monitored the effect of the mutations on PM targeting in Madin–Darby canine kidney cells. Our results show that the Vangl1 amino terminus lacks PM targeting determinants, and these are restricted to the carboxy terminus, including the predicted PDZBM motif at the C-terminus. PMID:24452931

  20. Injection of electrons with predominantly perpendicular energy into an area of toroidal field ripple in a tokamak plasma to improve plasma confinement

    DOEpatents

    Ono, Masayuki; Furth, Harold

    1993-01-01

    An electron injection scheme for controlling transport in a tokamak plasma. Electrons with predominantly perpendicular energy are injected into a ripple field region created by a group of localized poloidal field bending magnets. The trapped electrons then grad-B drift vertically toward the plasma interior until they are detrapped, charging the plasma negative. Calculations indicate that the highly perpendicular velocity electrons can remain stable against kinetic instabilities in the regime of interest for tokamak experiments. The penetration distance can be controlled by controlling the "ripple mirror ratio", the energy of the injected electrons, and their v.sub..perp. /v.sub.51 ratio. In this scheme, the poloidal torque due to the injected radial current is taken by the magnets and not by the plasma. Injection is accomplished by the flat cathode containing an ECH cavity to pump electrons to high v.sub..perp..

  1. Relativistic Laser Pulse Intensification with 3D Printed Micro-Tube Plasma Target

    NASA Astrophysics Data System (ADS)

    Ji, Liangliang; Snyder, Joseph; Pukhov, Alexander; Akli, Kramer

    2015-11-01

    The potential and applications of laser-plasma interactions (LPI) are restricted by the parameter space of existing lasers and targets. Advancing the laser intensity to the extreme regime is motivated by the production of energetic particle beams and by the quest to explore the exotic regimes of light-matter interaction. Target density and dimensions can always be varied to optimize the outcome. Here, we propose to create another degree of freedom in the parameter space of LPI using recent advances in 3D printing of materials. Fine structures at nm scale with high repetition and accuracy can nowadays be manufactured, allowing for a full precise control of the target. We demonstrate, via particle-in-cell (PIC) simulations, that 3D-printed micro-tube plasma (MTP) targets yield an intensity enhancement factor of 2-5. The novel MTP targets not only act as a plasma optical device to reach the 1023W/cm2 threshold based on today's intensities, but can also boost the generation of secondary particle and radiation sources. This work demonstrates that the combination of high contrast high power lasers and nano-3D printing techniques opens new paths in the intensity frontier and LPI micro-engineering.

  2. Experimental study of radiation power flux on the target surface during high heat plasma irradiation

    NASA Astrophysics Data System (ADS)

    Litunovsky, V. N.; Ovchinnikov, I. B.; Titov, V. A.

    2001-03-01

    Some new data of the experimental study of visible radiation from the plasma shielding layer (SL) on the target surface during high heat plasma-material interaction are given in the report. The experiments were performed on the VIKA facility. Long pulse ( τp=0.36 ms) high power ( Pirr˜100 GW m -2 plasma streams were used for irradiation of graphite and tungsten samples. The target inclination ( α=0° normal irradiation; 45°; 70°) and magnetic field ( B=0 to 3 T) were varied in experiments. It is shown that the values of ( Δλ≈400 to 700 nm) visible radiation power flux (VRPF) on the target surface can be characterised by the level of PR˜1 GW m -2 for normal irradiation in the presence of a magnetic field B=2 to 3 T. Inclination of targets leads to the reduction of this flux in conformity with the corresponding decrease of the irradiation power. The material of the target does not influence sufficiently on the level of the incident radiation power flux in the performed experiments.

  3. Ion kinetic effects on the ignition and burn of inertial confinement fusion targets: A multi-scale approach

    SciTech Connect

    Peigney, B. E.; Larroche, O.

    2014-12-15

    In this article, we study the hydrodynamics and burn of the thermonuclear fuel in inertial confinement fusion pellets at the ion kinetic level. The analysis is based on a two-velocity-scale Vlasov-Fokker-Planck kinetic model that is specially tailored to treat fusion products (suprathermal α-particles) in a self-consistent manner with the thermal bulk. The model assumes spherical symmetry in configuration space and axial symmetry in velocity space around the mean flow velocity. A typical hot-spot ignition design is considered. Compared with fluid simulations where a multi-group diffusion scheme is applied to model α transport, the full ion-kinetic approach reveals significant non-local effects on the transport of energetic α-particles. This has a direct impact on hydrodynamic spatial profiles during combustion: the hot spot reactivity is reduced, while the inner dense fuel layers are pre-heated by the escaping α-suprathermal particles, which are transported farther out of the hot spot. We show how the kinetic transport enhancement of fusion products leads to a significant reduction of the fusion yield.

  4. METACASPASE9 modulates autophagy to confine cell death to the target cells during Arabidopsis vascular xylem differentiation

    PubMed Central

    Escamez, Sacha; André, Domenique; Zhang, Bo; Bollhöner, Benjamin; Pesquet, Edouard; Tuominen, Hannele

    2016-01-01

    ABSTRACT We uncovered that the level of autophagy in plant cells undergoing programmed cell death determines the fate of the surrounding cells. Our approach consisted of using Arabidopsis thaliana cell cultures capable of differentiating into two different cell types: vascular tracheary elements (TEs) that undergo programmed cell death (PCD) and protoplast autolysis, and parenchymatic non-TEs that remain alive. The TE cell type displayed higher levels of autophagy when expression of the TE-specific METACASPASE9 (MC9) was reduced using RNAi (MC9-RNAi). Misregulation of autophagy in the MC9-RNAi TEs coincided with ectopic death of the non-TEs, implying the existence of an autophagy-dependent intercellular signalling from within the TEs towards the non-TEs. Viability of the non-TEs was restored when AUTOPHAGY2 (ATG2) was downregulated specifically in MC9-RNAi TEs, demonstrating the importance of autophagy in the spatial confinement of cell death. Our results suggest that other eukaryotic cells undergoing PCD might also need to tightly regulate their level of autophagy to avoid detrimental consequences for the surrounding cells. PMID:26740571

  5. Optical shaping of gas targets for laser-plasma ion sources

    NASA Astrophysics Data System (ADS)

    Dover, N. P.; Cook, N.; Tresca, O.; Ettlinger, O.; Maharjan, C.; Polyanskiy, M. N.; Shkolnikov, P.; Pogorelsky, I.; Najmudin, Z.

    2016-02-01

    We report on the experimental demonstration of a technique to generate steep density gradients in gas-jet targets of interest to laser-plasma ion acceleration. By using an intentional low-energy prepulse, we generated a hydrodynamic blast wave in the gas to shape the target prior to the arrival of an intense CO2 λ≈ 10m drive pulse. This technique has been recently shown to facilitate the generation of ion beams by shockwave acceleration (Tresca et al., Phys. Rev. Lett., vol. 115 (9), 2015, 094802). Here, we discuss and introduce a model to understand the generation of these blast waves and discuss in depth the experimental realisation of the technique, supported by hydrodynamics simulations. With appropriate prepulse energy and timing, this blast wave can generate steepened density gradients as short as &ap 20μm (1/e), opening up new possibilities for laser-plasma studies with near-critical gaseous targets.

  6. An experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion

    SciTech Connect

    Bradley, K.S.

    1993-02-11

    Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable--that is, it grows as it traverses the plasma. Though it has yet to be definitively tested, convective theory is often invoked to explain experimental observations, even when one or more of the theory`s assumptions are violated. In contrast, the experiments reported here not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter-critical density. This prevented other competing or coexisting phenomena from occurring, thereby providing clearly interpretable results. These are the first SBS experiments that were designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made.

  7. Propagation of shear Alvén waves in two-ion species plasmas confined by a nonuniform magnetic field

    SciTech Connect

    Farmer, W. A.; Morales, G. J.

    2013-08-15

    Ray tracing calculations are performed for shear Alfvén waves in two-ion species plasmas in which the magnetic field varies with position. Three different magnetic topologies of contemporary interest are explored: a linear magnetic mirror, a pure toroidal field, and a tokamak field. The wave frequency is chosen to lie in the upper propagation band, so that reflection at the ion-ion hybrid frequency can occur for waves originally propagating along the magnetic field direction. Calculations are performed for a magnetic well configuration used in recent experiments [S. T. Vincena et al., Geophys. Res. Lett. 38, L11101 (2011) and S. T. Vincena et al., Phys. Plasmas 20, 012111 (2013)] in the Large Plasma Device (LAPD) related to the ion-ion hybrid resonator. It is found that radial spreading cannot explain the relatively low values of the resonator quality factor (Q) measured in those experiments, even when finite ion temperature is considered. This identifies that a damping mechanism is present that is at least an order of magnitude larger than dissipation due to radial energy loss. Calculations are also performed for a magnetic field with pure toroidal geometry, without a poloidal field, as in experiments being planned for the Enormous Toroidal Plasma Device. In this case, the effects of field-line curvature cause radial reflections. A poloidal field is included to explore a tokamak geometry with plasma parameters expected in ITER. When ion temperature is ignored, it is found that the ion-ion hybrid resonator can exist and trap waves for multiples bounces. The effects of finite ion temperature combine with field line curvature to cause the reflection point to move towards the tritium cyclotron frequency when electron temperature is negligible. However, for ITER parameters, it is shown that the electrons must be treated in the adiabatic limit to properly describe resonator phenomena.

  8. Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma.

    PubMed

    Xu, G S; Wan, B N; Wang, H Q; Guo, H Y; Naulin, V; Rasmussen, J Juul; Nielsen, A H; Wu, X Q; Yan, N; Chen, L; Shao, L M; Chen, R; Wang, L; Zhang, W

    2016-03-01

    A new model for the low-to-high (L-H) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L-H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L-H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.

  9. Low-to-High Confinement Transition Mediated by Turbulence Radial Wave Number Spectral Shift in a Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Xu, G. S.; Wan, B. N.; Wang, H. Q.; Guo, H. Y.; Naulin, V.; Rasmussen, J. Juul; Nielsen, A. H.; Wu, X. Q.; Yan, N.; Chen, L.; Shao, L. M.; Chen, R.; Wang, L.; Zhang, W.

    2016-03-01

    A new model for the low-to-high (L -H ) confinement transition has been developed based on a new paradigm for turbulence suppression by velocity shear [G. M. Staebler et al., Phys. Rev. Lett. 110, 055003 (2013)]. The model indicates that the L -H transition can be mediated by a shift in the radial wave number spectrum of turbulence, as evidenced here, for the first time, by the direct observation of a turbulence radial wave number spectral shift and turbulence structure tilting prior to the L -H transition at tokamak edge by direct probing. This new mechanism does not require a pretransition overshoot in the turbulent Reynolds stress, shunting turbulence energy to zonal flows for turbulence suppression as demonstrated in the experiment.

  10. Quantify Plasma Response to Non-Axisymmetric (3D) Magnetic Fields in Tokamaks, Final Report for FES (Fusion Energy Sciences) FY2014 Joint Research Target

    SciTech Connect

    Strait, E. J.; Park, J. -K.; Marmar, E. S.; Ahn, J. -W.; Berkery, J. W.; Burrell, K. H.; Canik, J. M.; Delgado-Aparicio, L.; Ferraro, N. M.; Garofalo, A. M.; Gates, D. A.; Greenwald, M.; Kim, K.; King, J. D.; Lanctot, M. J.; Lazerson, S. A.; Liu, Y. Q.; Lore, J. D.; Menard, J. E.; Nazikian, R.; Shafer, M. W.; Paz-Soldan, C.; Reiman, A. H.; Rice, J. E.; Sabbagh, S. A.; Sugiyama, L.; Turnbull, A. D.; Volpe, F.; Wang, Z. R.; Wolfe, S. M.

    2014-09-30

    The goal of the 2014 Joint Research Target (JRT) has been to conduct experiments and analysis to investigate and quantify the response of tokamak plasmas to non-axisymmetric (3D) magnetic fields. Although tokamaks are conceptually axisymmetric devices, small asymmetries often result from inaccuracies in the manufacture and assembly of the magnet coils, or from nearby magnetized objects. In addition, non-axisymmetric fields may be deliberately applied for various purposes. Even at small amplitudes of order 10-4 of the main axisymmetric field, such “3D” fields can have profound impacts on the plasma performance. The effects are often detrimental (reduction of stabilizing plasma rotation, degradation of energy confinement, localized heat flux to the divertor, or excitation of instabilities) but may in some case be beneficial (maintenance of rotation, or suppression of instabilities). In general, the magnetic response of the plasma alters the 3D field, so that the magnetic field configuration within the plasma is not simply the sum of the external 3D field and the original axisymmetric field. Typically the plasma response consists of a mixture of local screening of the external field by currents induced at resonant surfaces in the plasma, and amplification of the external field by stable kink modes. Thus, validated magnetohydrodynamic (MHD) models of the plasma response to 3D fields are crucial to the interpretation of existing experiments and the prediction of plasma performance in future devices. The non-axisymmetric coil sets available at each facility allow well-controlled studies of the response to external 3D fields. The work performed in support of the 2014 Joint Research Target has included joint modeling and analysis of existing experimental data, and collaboration on new experiments designed to address the goals of the JRT. A major focus of the work was validation of numerical models through quantitative comparison to experimental data, in

  11. Potential cellular targets and antibacterial efficacy of atmospheric pressure non-thermal plasma.

    PubMed

    Alkawareek, Mahmoud Y; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2014-02-01

    Atmospheric pressure non-thermal plasma (APNTP) has been gaining increasing interest as a new alternative antibacterial approach. Although this approach has demonstrated promising antibacterial activity, its exact mechanism of action remains unclear. Mechanistic elucidation of the antimicrobial activity will facilitate development and rational optimisation of this approach for potential medical applications. In this study, the antibacterial efficacy of an in-house-built APNTP jet was evaluated alongside an investigation of the interactions between APNTP and major cellular components in order to identify the potential cellular targets involved in plasma-mediated bacterial destruction mechanisms. The investigated plasma jet exhibited excellent, rapid antibacterial activity against a selected panel of clinically significant bacterial species including Bacillus cereus, meticillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa, all of which were completely inactivated within 2 min of plasma exposure. Plasma-mediated damaging effects were observed, to varying degrees, on all of the investigated cellular components including DNA, a model protein enzyme, and lipid membrane integrity and permeability. The antibacterial efficacy of APNTP appears to involve a multiple-target mechanism, which potentially reduces the likelihood of emergence of microbial resistance towards this promising antimicrobial approach. However, cellular membrane damage and resulting permeability perturbation was found to be the most likely rate-determining step in this mechanism.

  12. Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law.

    PubMed

    Joglekar, A S; Thomas, A G R; Fox, W; Bhattacharjee, A

    2014-03-14

    In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfvènic flows. We find that this mechanism is only relevant in a high β plasma. However, the Hall parameter ωcτei can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system.

  13. Proton Radiography of Spontaneous Fields, Plasma Flows and Dynamics in X-Ray Driven Inertial-Confinement Fusion Implosions

    NASA Astrophysics Data System (ADS)

    Li, C. K.; Seguin, F. H.; Frenje, J. A.; Rosenberg, M.; Zylstra, A. B.; Rinderknecht, H. G.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Town, R. P. J.; Betti, R.; Knauer, J. P.; Meyerhofer, D. D.; Back, C. A.; Kilkenny, J. D.; Nikroo, A.

    2010-11-01

    Backlighting of x-ray-driven implosions in empty hohlraums with mono-energetic protons on the OMEGA laser facility has allowed a number of important phenomena to be observed. Several critical parameters were determined, including plasma flow, three types of spontaneous electric fields and megaGauss magnetic fields. These results provide insight into important issues in indirect-drive ICF. Even though the cavity is effectively a Faraday cage, the strong, local fields inside the hohlraum can affect laser-plasma instabilities, electron distributions and implosion symmetry. They are of fundamental scientific importance for a range of new experiments at the frontiers of high-energy-density physics. Future experiments designed to characterize the field formation and evolution in low-Z gas fill hohlraums will be discussed.

  14. An Experimental Study of Continuous Plasma Flows Driven by a Confined Arc in a Transverse Magnetic Field

    NASA Technical Reports Server (NTRS)

    Barger, R. L.; Brooks, J. D.; Beasley, W. D.

    1961-01-01

    A crossed-field, continuous-flow plasma accelerator has been built and operated. The highest measured velocity of the flow, which was driven by the interaction of the electric and magnetic fields, was about 500 meters per second. Some of the problems discussed are ion slip, stability and uniformity of the discharge, effect of the magnetic field on electron emission, use of preionization, and electrode contamination.

  15. Approaching to the ideal condition of plasma confinement by applying external resonant fields in IR-T1 tokamak

    NASA Astrophysics Data System (ADS)

    Meshkani, Sakineh; Ghoranneviss, Mahmood; Lafouti, Mansoureh

    2015-06-01

    For understanding the effect of resonant helical magnetic field (RHF) and bias on the edge plasma turbulent transport, the radial and poloidal electric field (Er, EP ), poloidal and toroidal magnetic field (BP, Br ) were detected by the Langmuir probe, magnetic probe and diamagnetic loop. The poloidal, toroidal and radial velocity (VP, Vr, Vt ) can be determined from the electric and magnetic field. In the present work, we have investigated the effect of the magnitude of bias (V bias = 200v, V bias = 320v) on Er, EP, BP, Bt, VP, Vr, Vt . Moreover, we applied RHF with L = 2, L = 3 and L = 2 and 3 and investigate the effect of the helical windings radius on above parameters. Also, the experiment was repeated by applying the positive biasing potentials and RHF's simultaneously. The results show that by applying bias to the plasma at t = 15 msec at r/a = 0.9, Er , BP and Bt increase while EP decreases. The best modification occurs at V bias = 200v. By applying RHF to the plasma, both the electric and magnetic field vary. Er reaches the highest in the presence of RHF with L = 3. The same results are obtained for BP, Bt, VP and Vt . While the inverse results are obtained for EP and Vr . Finally, RHF and bias are applied simultaneously to the plasma. With applied bias with V bias = 200v and RHF with L = 2 and 3, we reach to the ideal circumstance. The same results obtain in the situation with V bias = 320v and RHF with L = 2 and 3.

  16. Scattered light diagnostics of overdense plasma cavity in solid targets irradiated by an ultraintense laser pulse.

    PubMed

    Andreev, A A; Zhidkov, A G; Uesaka, M; Kinoshita, K; Platonov, K Yu

    2002-09-01

    The light scattered backward from a target illuminated by ultraintense laser pulses carries important information about the nonlinear laser-plasma interaction. We analyze the usefulness of this information by plasma corona analysis with the help of an analytical model we developed, and particle-in-cell simulation. The spectrum of scattered light is shown to be shifted, to be broadened, and to be modulated, in comparison with the initial laser spectrum, and the spectral shift is an indicator of laser pulse contrast ratio.

  17. Inertial confinement fusion

    SciTech Connect

    Powers, L.; Condouris, R.; Kotowski, M.; Murphy, P.W.

    1992-01-01

    This issue of the ICF Quarterly contains seven articles that describe recent progress in Lawrence Livermore National Laboratory's ICF program. The Department of Energy recently initiated an effort to design a 1--2 MJ glass laser, the proposed National Ignition Facility (NIF). These articles span various aspects of a program which is aimed at moving forward toward such a facility by continuing to use the Nova laser to gain understanding of NIF-relevant target physics, by developing concepts for an NIF laser driver, and by envisioning a variety of applications for larger ICF facilities. This report discusses research on the following topics: Stimulated Rotational Raman Scattering in Nitrogen; A Maxwell Equation Solver in LASNEX for the Simulation of Moderately Intense Ultrashort Pulse Experiments; Measurements of Radial Heat-Wave Propagation in Laser-Produced Plasmas; Laser-Seeded Modulation Growth on Directly Driven Foils; Stimulated Raman Scattering in Large-Aperture, High-Fluence Frequency-Conversion Crystals; Fission Product Hazard Reduction Using Inertial Fusion Energy; Use of Inertial Confinement Fusion for Nuclear Weapons Effects Simulations.

  18. Ionization, ion distribution, and ion focusing in laser plasmas from atomic and diatomic targets

    SciTech Connect

    Srivastava, S. N.; Rohr, K.; Sinha, B. K.

    2006-04-01

    Charge-resolved measurements of the total number of particles from plasmas produced from planar, monoatomic targets of copper and tungsten as well as the binary targets of copper and tungsten are reported, using a 125 mJ, 5 ns, Nd:YAG laser, at a laser intensity of about 10{sup 10} W/cm{sup 2}. The measurements show a severe quenching of the ionization states in the case of the diatomic targets. These measurements and their variations with ionization state support the theoretical investigations of plasma motion under the influence of the viscous force in case of plasmas consisting of light and heavy particles. Gaussian width measurements of the angular particle distribution showed a focusing effect towards the target normal, the width decreasing as the ion mass and ionization state increased. From the analysis of the theoretical results on self-similarity expansion it is concluded that the ion acceleration due to the built-in electrostatic potential is not significant.

  19. Plasma physics. Proceedings. 7th Latin American Workshop on Plasma Physics (VII LAWPP 97), Caracas (Venezuela), 20 - 31 Jan 1997.

    NASA Astrophysics Data System (ADS)

    Martín, P.; Puerta, J.

    The following topics were dealt with: general plasma theory, plasma confinement, shock waves and instabilities in plasma, plasma spectroscopy, astrophysical and space plasmas, pulse power experiments, plasma processing.

  20. Status of target physics for inertial confinement fusion: Report on the review at DOE Headquarters, Germantown, MD on November 14--17, 1988

    SciTech Connect

    Not Available

    1990-03-09

    A four day review to assess the status of target physics of inertial confinement fusion was held at US Department of Energy (DOE) Headquarters on November 14--17, 1988. This review completes the current series of reviews of the inertial fusion program elements to assess the status of the data base for a decision to proceed with the proposed Laboratory Microfusion Facility (LMF) that is being planned. In addition to target physics, the program elements that have been reviewed previously include the driver technology development for KrF and solid-state lasers, and the light-on beam pulsed power system. This series of reviews was undertaken for internal DOE assessment in anticipation of the ICF program review mandated by the Congress in 1988 to be completed in 1990 to assess the significance and implications of the progress that has been realized in the laboratory and the underground Halite/Centurion experiments. For this target physics review, both the direct and the indirect drive approaches were considered. The principal issues addressed in this review were: Is the present target physics data base adequate for a decision to proceed with design and construction of LMF now as opposed to continue planning activities at this time What specific additional target physics data are desirable to reduce the risk for a DOE decision to construct an LMF What is the role for continuation of Halite/Centurion experiments What priority should be given to the direct drive approach Are the program elements optimally structured to resolve the critical issues for an LMF decision Specific findings relating to these five issues are summarized in the following.

  1. Development of diagnostic and manipulation systems for space-charge dominated electron beams and confined electron plasmas in ELTRAP

    SciTech Connect

    Rome, M.; Cavaliere, F.; Maero, G.; Paroli, B.; Pozzoli, R.; Cavenago, M.; Ikram, M.

    2013-03-19

    Modifications have been implemented in the Penning-Malmberg device ELTRAP aimed at performing studies on the dynamics of space-charge dominated nanosecond electron bunches traveling along the magnetic field. In particular, a Thomson backscattering apparatus has been developed where an infrared (IR) laser pulse collides with the bunched electron beam. The frequency-shifted backscattered radiation, acquired by means of a photomultiplier (PMT), can be exploited to evaluate information on energy, energy spread and density of the bunch. The achievable sensitivity of the diagnostics has been estimated, and valuable information on the main parameters affecting the signal-to-noise (S/N) ratio has been obtained [B. Paroli, F. Cavaliere, M. Cavenago, F. De Luca, M. Ikram, G. Maero, C. Marini, R. Pozzoli, and M. Rome, JINST 7, P01008 (2012)]. A series of upgrades are under way, aimed at increasing the S/N ratio through the use of a new laser for the electron source, the insertion of a stray light shield, and the optimization of the detection electronics. Moreover, electromagnetic simulations relevant to the design and implementation of a microwave heating system are presented. The generation of an electron plasma in ELTRAP by means of a low-power radio frequency (RF) drive in the MHz range applied on one of the trap electrodes and under ultra-high vacuum (UHV) conditions has previously been demonstrated [B. Paroli, F. De Luca, G. Maero, F. Pozzoli, and M. Rome, Plasma Sources Sci. Technol. 19, 045013 (2010)]. The new heating system will allow the extension of the RF studies to the GHz range and in particular the production of a more energetic electron plasma via cyclotron resonant excitation.

  2. Development of diagnostic and manipulation systems for space-charge dominated electron beams and confined electron plasmas in ELTRAP

    NASA Astrophysics Data System (ADS)

    Romé, M.; Cavaliere, F.; Cavenago, M.; Ikram, M.; Maero, G.; Paroli, B.; Pozzoli, R.

    2013-03-01

    Modifications have been implemented in the Penning-Malmberg device ELTRAP aimed at performing studies on the dynamics of space-charge dominated nanosecond electron bunches traveling along the magnetic field. In particular, a Thomson backscattering apparatus has been developed where an infrared (IR) laser pulse collides with the bunched electron beam. The frequency-shifted backscattered radiation, acquired by means of a photomultiplier (PMT), can be exploited to evaluate information on energy, energy spread and density of the bunch. The achievable sensitivity of the diagnostics has been estimated, and valuable information on the main parameters affecting the signal-to-noise (S/N) ratio has been obtained [B. Paroli, F. Cavaliere, M. Cavenago, F. De Luca, M. Ikram, G. Maero, C. Marini, R. Pozzoli, and M. Romé, JINST 7, P01008 (2012)]. A series of upgrades are under way, aimed at increasing the S/N ratio through the use of a new laser for the electron source, the insertion of a stray light shield, and the optimization of the detection electronics. Moreover, electromagnetic simulations relevant to the design and implementation of a microwave heating system are presented. The generation of an electron plasma in ELTRAP by means of a low-power radio frequency (RF) drive in the MHz range applied on one of the trap electrodes and under ultra-high vacuum (UHV) conditions has previously been demonstrated [B. Paroli, F. De Luca, G. Maero, F. Pozzoli, and M. Romé, Plasma Sources Sci. Technol. 19, 045013 (2010)]. The new heating system will allow the extension of the RF studies to the GHz range and in particular the production of a more energetic electron plasma via cyclotron resonant excitation.

  3. Metal doped fluorocarbon polymer films prepared by plasma polymerization using an RF planar magnetron target

    NASA Astrophysics Data System (ADS)

    Biederman, H.; Holland, L.

    1983-07-01

    Fluorocarbon films have been prepared by plasma polymerization of CF4 using an RF planar magnetron with an aluminium target. More than one order of magnitude higher deposition rate has been achieved in comparison with an r.f. diode system operated under similar conditions of monomer pressure and flow rate and power input. A glow discharge in a CF4[25%]-argon [75%] mixture was used to incorporate aluminium from a target electrode into the polymer films. The foregoing mixture and another based on CF4 [87%]-argon [13%] were used in the RF discharge with a copper target. Some experiments with a gold target and pure CF4 as the inlet gas were also made. The film structure was examined by SEM and TEM and characteristic micrographs are presented here. The composition of the films was estimated from an AES study. The sheet resistivity of the metal/polymer film complexes was determined.

  4. Atomic processes in high-density plasmas

    NASA Astrophysics Data System (ADS)

    More, R. M.

    Dense atomic plasmas such as that produced in inertial confinement fusion are reviewed. The target implosion physics along with the associated atomic physics, i.e., free electron collision phenomena, electron states I, electron states II, and nonequilibrum plasma states are described.

  5. Velocity distribution function of electrons plasma produced by high power laser pulse interacting aluminum target

    NASA Astrophysics Data System (ADS)

    Mahdieh, M. H.; Razi, E. M.

    2010-09-01

    This paper presents the experimental results of studying the distribution function of electrons plasma produced by irradiating aluminum target by nanosecond pulsed laser in vacuum. The laser beam was provided by second harmonic of a Q-switched Nd:YAG pulsed laser with ~10 nsec pulse duration and energy of 70 mJ. A home made Faraday cup was used for detecting the current signal. From analyzing the time of flight (TOF) experimental distribution function was determined. Comparing the experimental distribution function with Maxwell-Boltzamnn and effusion distribution functions, the electron temperature was estimated. From the experimental results, the velocity of maximum electron flux was determined. In this study the influence of the probe position and biasing voltage was investigated. The results show that the velocity of maximum electron flux and associated temperature rises with distance from the target surface. The results also show that effusion distribution function is more appropriate for modeling such plasma.

  6. Non-Invasive Prenatal Diagnosis of Lethal Skeletal Dysplasia by Targeted Capture Sequencing of Maternal Plasma

    PubMed Central

    Wang, Yaoshen; Chen, Chao; Gao, Changxin; Yu, Song; Liu, Yan; Song, Wei; Asan; Zhu, Hongmei; Yang, Ling; Deng, Hongmei; Su, Yue; Yi, Xin

    2016-01-01

    Background Since the discovery of cell-free foetal DNA in the plasma of pregnant women, many non-invasive prenatal testing assays have been developed. In the area of skeletal dysplasia diagnosis, some PCR-based non-invasive prenatal testing assays have been developed to facilitate the ultrasound diagnosis of skeletal dysplasias that are caused by de novo mutations. However, skeletal dysplasias are a group of heterogeneous genetic diseases, the PCR-based method is hard to detect multiple gene or loci simultaneously, and the diagnosis rate is highly dependent on the accuracy of the ultrasound diagnosis. In this study, we investigated the feasibility of using targeted capture sequencing to detect foetal de novo pathogenic mutations responsible for skeletal dysplasia. Methodology/Principal Findings Three families whose foetuses were affected by skeletal dysplasia and two control families whose foetuses were affected by other single gene diseases were included in this study. Sixteen genes related to some common lethal skeletal dysplasias were selected for analysis, and probes were designed to capture the coding regions of these genes. Targeted capture sequencing was performed on the maternal plasma DNA, the maternal genomic DNA, and the paternal genomic DNA. The de novo pathogenic variants in the plasma DNA data were identified using a bioinformatical process developed for low frequency mutation detection and a strict variant interpretation strategy. The causal variants could be specifically identified in the plasma, and the results were identical to those obtained by sequencing amniotic fluid samples. Furthermore, a mean of 97% foetal specific alleles, which are alleles that are not shared by maternal genomic DNA and amniotic fluid DNA, were identified successfully in plasma samples. Conclusions/Significance Our study shows that capture sequencing of maternal plasma DNA can be used to non-invasive detection of de novo pathogenic variants. This method has the potential

  7. Characterization of a laser-plasma extreme-ultraviolet source using a rotating cryogenic Xe target

    NASA Astrophysics Data System (ADS)

    Amano, S.; Masuda, K.; Shimoura, A.; Miyamoto, S.; Mochizuki, T.

    2010-10-01

    A laser-plasma source for extreme-ultraviolet (EUV) light that uses a rotating cryogenic solid-state Xe target has been characterized. We focused on parameters at the wavelength of 13.5 nm with 2% bandwidth required for an EUV lithography source and investigated improvements of the conversion efficiency (CE). With the drum rotating, there was an increase in CE and less fast ions compared with the case for the drum at rest. It is considered that the Xe gas on the target surface can produce optimal-scale plasma, and satellite emission lines in Xe plasma effectively increase the EUV intensity, and the ion number is decreased by the gas curtain effect. The dependence of CE on the laser wavelength, laser energy and intensity also studied. As a result, the maximum CE was 0.9% at 13.5 nm with 2% bandwidth under the optimal condition. By continuous irradiation of a Nd:YAG slab laser at a repetition rate of 320 Hz and an average power of 110 W, the target continuously generated EUV light with an average power of 1 W at 13.5 nm with 2% bandwidth. The achieved performances provide valuable information for the design of a future EUV lithography source.

  8. [Experimental investigation of laser plasma soft X-ray source with gas target].

    PubMed

    Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin

    2003-02-01

    This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions.

  9. Progress in plasma liner modeling for MIF

    NASA Astrophysics Data System (ADS)

    Loverich, John; Hakim, Ammar; Zhou, Sean

    2009-11-01

    Magnetic confinement fusion and inertial confinement fusion represent the two extremes in terms of density and confinement time in fusion energy research. Both approaches have been studied extensively through the decades pushing technology to the limits. An alternative fusion approach exists between these regimes called magnetized target fusion. In magnetized target fusion longer confinement times are achieved than in ICF through the use of strong magnetic fields, the long confinement time reduces the required plasma density to reach ignition--the approach has advantages over MFE in that it is much more compact and higher density. This work explores computationally a form of magnetized target implosion using a plasma liner. This concept is to be compared with solid liner implosion approach which may not be commercially viable as a reactor due to the ``standoff'' problem, portions of the device are destroyed with each target implosion. We present simulation results of plasma liner formation, jet merging, and plasma jet magnetized target interaction using a fluid plasma code (TxFluids) developed at Tech-X corporation.

  10. Ion-kinetic simulations of D-3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number

    DOE PAGESBeta

    Larroche, O.; Rinderknecht, H. G.; Rosenberg, M. J.; Hoffman, N. M.; Atzeni, S.; Petrasso, R. D.; Amendt, P. A.; Seguin, F. H.

    2016-01-06

    Experiments designed to investigate the transition to non-collisional behavior in D3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λc increase with respect to the target radius R (i.e., when the Knudsen number NK = λc/R grows). To take properly into account large NK's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of NK, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surface brightness, have been compared with themore » experimental data and with the results of hydrodynamical simulations, some of which include an ad hocmodeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-NK case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-NK case, the agreement is much worse. Furthermore, the remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.« less

  11. SOLVING THE STAND-OFF PROBLEM FOR MAGNETIZED TARGET FUSION: PLASMA STREAMS AS DISPOSABLE ELECTRODES, PLUS A LOCAL SPHERICAL BLANKET

    SciTech Connect

    Ryutov, D D; Thio, Y F

    2006-03-21

    In a fusion reactor based on the Magnetized Target Fusion approach, the permanent power supply has to deliver currents up to a few mega-amperes to the target dropped into the reaction chamber. All the structures situated around the target will be destroyed after every pulse and have to be replaced at a frequency of 1 to 10 Hz. In this paper, an approach based on the use of spherical blanket surrounding the target, and pulsed plasma electrodes connecting the target to the power supply, is discussed. A brief physic analysis of the processes associated with creation of plasma electrodes is discussed.

  12. Cold atmospheric plasma treatment selectively targets head and neck squamous cell carcinoma cells

    PubMed Central

    GUERRERO-PRESTON, RAFAEL; OGAWA, TAKENORI; UEMURA, MAMORU; SHUMULINSKY, GARY; VALLE, BLANCA L.; PIRINI, FRANCESCA; RAVI, RAJANI; SIDRANSKY, DAVID; KEIDAR, MICHAEL; TRINK, BARRY

    2014-01-01

    The treatment of locoregional recurrence (LRR) of head and neck squamous cell carcinoma (HNSCC) often requires a combination of surgery, radiation therapy and/or chemotherapy. Survival outcomes are poor and the treatment outcomes are morbid. Cold atmospheric plasma (CAP) is an ionized gas produced at room temperature under laboratory conditions. We have previously demonstrated that treatment with a CAP jet device selectively targets cancer cells using in vitro melanoma and in vivo bladder cancer models. In the present study, we wished to examine CAP selectivity in HNSCC in vitro models, and to explore its potential for use as a minimally invasive surgical approach that allows for specific cancer cell or tumor tissue ablation without affecting the surrounding healthy cells and tissues. Four HNSCC cell lines (JHU-022, JHU-028, JHU-029, SCC25) and 2 normal oral cavity epithelial cell lines (OKF6 and NOKsi) were subjected to cold plasma treatment for durations of 10, 30 and 45 sec, and a helium flow of 20 l/min−1 for 10 sec was used as a positive treatment control. We showed that cold plasma selectively diminished HNSCC cell viability in a dose-response manner, as evidenced by MTT assays; the viability of the OKF6 cells was not affected by the cold plasma. The results of colony formation assays also revealed a cell-specific response to cold plasma application. Western blot analysis did not provide evidence that the cleavage of PARP occurred following cold plasma treatment. In conclusion, our results suggest that cold plasma application selectively impairs HNSCC cell lines through non-apoptotic mechanisms, while having a minimal effect on normal oral cavity epithelial cell lines. PMID:25050490

  13. Cold atmospheric plasma treatment selectively targets head and neck squamous cell carcinoma cells.

    PubMed

    Guerrero-Preston, Rafael; Ogawa, Takenori; Uemura, Mamoru; Shumulinsky, Gary; Valle, Blanca L; Pirini, Francesca; Ravi, Rajani; Sidransky, David; Keidar, Michael; Trink, Barry

    2014-10-01

    The treatment of locoregional recurrence (LRR) of head and neck squamous cell carcinoma (HNSCC) often requires a combination of surgery, radiation therapy and/or chemotherapy. Survival outcomes are poor and the treatment outcomes are morbid. Cold atmospheric plasma (CAP) is an ionized gas produced at room temperature under laboratory conditions. We have previously demonstrated that treatment with a CAP jet device selectively targets cancer cells using in vitro melanoma and in vivo bladder cancer models. In the present study, we wished to examine CAP selectivity in HNSCC in vitro models, and to explore its potential for use as a minimally invasive surgical approach that allows for specific cancer cell or tumor tissue ablation without affecting the surrounding healthy cells and tissues. Four HNSCC cell lines (JHU-022, JHU-028, JHU-029, SCC25) and 2 normal oral cavity epithelial cell lines (OKF6 and NOKsi) were subjected to cold plasma treatment for durations of 10, 30 and 45 sec, and a helium flow of 20 l/min-1 for 10 sec was used as a positive treatment control. We showed that cold plasma selectively diminished HNSCC cell viability in a dose-response manner, as evidenced by MTT assays; the viability of the OKF6 cells was not affected by the cold plasma. The results of colony formation assays also revealed a cell-specific response to cold plasma application. Western blot analysis did not provide evidence that the cleavage of PARP occurred following cold plasma treatment. In conclusion, our results suggest that cold plasma application selectively impairs HNSCC cell lines through non-apoptotic mechanisms, while having a minimal effect on normal oral cavity epithelial cell lines.

  14. Targets for high power neutral beams

    SciTech Connect

    Kim, J.

    1980-01-01

    Stopping high-power, long-pulse beams is fast becoming an engineering challenge, particularly in neutral beam injectors for heating magnetically confined plasmas. A brief review of neutral beam target technology is presented along with heat transfer calculations for some selected target designs.

  15. Enhanced energy localization and heating in high contrast ultra-intense laser produced plasmas via novel conical micro-target design

    NASA Astrophysics Data System (ADS)

    Rassuchine, J.; d'Humières, E.; Baton, S.; Fuchs, J.; Guillou, P.; Koenig, M.; Kodama, R.; Nakatsutsumi, M.; Norimatsu, T.; Batani, D.; Morace, A.; Redaelli, R.; Gremillet, L.; Rousseaux, C.; Dorchies, F.; Fourment, C.; Santos, J. J.; Adams, J.; Korgan, G.; Malekos, S.; Sentoku, Y.; Cowan, T. E.

    2008-05-01

    We report new experiments showing enhanced laser-target coupling and energy localization using nano-fabricated micro-conical Cu targets performed at the 100 TW CPA laser at LULI. A comparison was made between 1ω (λ = 1.057 μm, I = 1019 W/cm2) and 2ω (λ = 0.53 μm, I = 4-8 × 1018 W/cm2) irradiation to determine the effect of ASE induced preformed plasma filling the cone, using as principal diagnostics 2D Cu Kα imaging (transverse and rear-side), and high-resolution conical crystal spectroscopy of the Cu Kα bands. The 2ω irradiation exhibits laser absorption up to 50 μm deeper into the cone tip (versus at 1 ω), with a commensurately smaller Kα emission zone. Spectroscopy indicates a higher average charge state for the Cu emission at 2ω, with some shots exhibiting up to at least O-like emission. We deduce that micro-cone targets have similar performance in terms of material heating as a 50 μm diameter reduced mass target, despite a 900-fold larger mass. The observed enhancement in energy localization and heating in the cone geometry is supported by 2D collisional PIC simulations which indicate the presence of self-generated resistive magnetic field structures (>= 10 MG) which confine the energetic electrons to the tip region

  16. Masked-backlighter technique used to simultaneously image x-ray absorption and x-ray emission from an inertial confinement fusion plasma

    SciTech Connect

    Marshall, F. J. Radha, P. B.

    2014-11-15

    A method to simultaneously image both the absorption and the self-emission of an imploding inertial confinement fusion plasma has been demonstrated on the OMEGA Laser System. The technique involves the use of a high-Z backlighter, half of which is covered with a low-Z material, and a high-speed x-ray framing camera aligned to capture images backlit by this masked backlighter. Two strips of the four-strip framing camera record images backlit by the high-Z portion of the backlighter, while the other two strips record images aligned with the low-Z portion of the backlighter. The emission from the low-Z material is effectively eliminated by a high-Z filter positioned in front of the framing camera, limiting the detected backlighter emission to that of the principal emission line of the high-Z material. As a result, half of the images are of self-emission from the plasma and the other half are of self-emission plus the backlighter. The advantage of this technique is that the self-emission simultaneous with backlighter absorption is independently measured from a nearby direction. The absorption occurs only in the high-Z backlit frames and is either spatially separated from the emission or the self-emission is suppressed by filtering, or by using a backlighter much brighter than the self-emission, or by subtraction. The masked-backlighter technique has been used on the OMEGA Laser System to simultaneously measure the emission profiles and the absorption profiles of polar-driven implosions.

  17. Plasma protein binding of an antisense oligonucleotide targeting human ICAM-1 (ISIS 2302).

    PubMed

    Watanabe, Tanya A; Geary, Richard S; Levin, Arthur A

    2006-01-01

    In vitro ultrafiltration was used to determine the plasma protein-binding characteristics of phosphorothioate oligonucleotides (PS ODNs). Although there are binding data on multiple PS ODNs presented here, the focus of this research is on the protein-binding characteristics of ISIS 2302, a PS ODN targeting human intercellular adhesion molecule-1 (ICAM-1) mRNA, which is currently in clinical trials for the treatment of ulcerative colitis. ISIS 2302 was shown to be highly bound (> 97%) across species (mouse, rat, monkey, human), with the mouse having the least degree of binding. ISIS 2302 was highly bound to albumin and, to a lesser, extent alpha2-macroglobulin and had negligible binding to alpha1-acid glycoprotein. Ten shortened ODN metabolites (8, 10, and 12-19 nucleotides [nt] in length, truncated from the 3' end) were evaluated in human plasma. The degree of binding was reduced as the ODN metabolite length decreased. Three additional 20-nt (20-mer) PS ODNs (ISIS 3521, ISIS 2503, and ISIS 5132) of varying sequence but similar chemistry were evaluated. Although the tested PS ODNs were highly bound to plasma proteins, suggesting a commonality within the chemical class, these results suggested that the protein-binding characteristics in human plasma may be sequence dependent. Lastly, drug displacement studies with ISIS 2302 and other concomitant drugs with known protein-binding properties were conducted to provide information on potential drug interactions. Coadministered ISIS 2302 and other high-binding drugs evaluated in this study did not displace one another at supraclinical plasma concentrations and, thus, are not anticipated to cause any pharmacokinetic interaction in the clinic as a result of the displacement of binding to plasma proteins.

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

    SciTech Connect

    Rapp, Juergen; Aaron, A. M.; Bell, Gary L.; Burgess, Thomas W.; Ellis, Ronald James; Giuliano, D.; Howard, R.; Kiggans, James O.; Lessard, Timothy L.; Ohriner, Evan Keith; Perkins, Dale E.; Varma, Venugopal Koikal

    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 panel 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

  19. Measurement of Neutrons Produced by Beam-Target Interactions via a Coaxial Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Cauble, Scott; Poehlmann, Flavio; Rieker, Gregory; Cappelli, Mark

    2011-10-01

    This poster presents a method to measure neutron yield from a coaxial plasma accelerator. Stored electrical energies between 1 and 19 kJ are discharged within a few microseconds across the electrodes of the coaxial gun, accelerating deuterium gas samples to plasma beam energies well beyond the keV energy range. The focus of this study is to examine the interaction of the plasma beam with a deuterated target by designing and fabricating a detector to measure neutron yield. Given the strong electromagnetic pulse associated with our accelerator, indirect measurement of neutrons via threshold-dependent nuclear activation serves as both a reliable and definitive indicator of high-energy particles for our application. Upon bombardment with neutrons, discs or stacks of metal foils placed near the deuterated target undergo nuclear activation reactions, yielding gamma-emitting isotopes whose decay is measured by a scintillation detector system. By collecting gamma ray spectra over time and considering nuclear cross sections, the magnitude of the original neutron pulse is inferred.

  20. Nanocrystalline-Si-dot multi-layers fabrication by chemical vapor deposition with H-plasma surface treatment and evaluation of structure and quantum confinement effects

    SciTech Connect

    Kosemura, Daisuke Mizukami, Yuki; Takei, Munehisa; Numasawa, Yohichiroh; Ogura, Atsushi; Ohshita, Yoshio

    2014-01-15

    100-nm-thick nanocrystalline silicon (nano-Si)-dot multi-layers on a Si substrate were fabricated by the sequential repetition of H-plasma surface treatment, chemical vapor deposition, and surface oxidation, for over 120 times. The diameter of the nano-Si dots was 5–6 nm, as confirmed by both the transmission electron microscopy and X-ray diffraction analysis. The annealing process was important to improve the crystallinity of the nano-Si dot. We investigated quantum confinement effects by Raman spectroscopy and photoluminescence (PL) measurements. Based on the experimental results, we simulated the Raman spectrum using a phenomenological model. Consequently, the strain induced in the nano-Si dots was estimated by comparing the experimental and simulated results. Taking the estimated strain value into consideration, the band gap modulation was measured, and the diameter of the nano-Si dots was calculated to be 5.6 nm by using PL. The relaxation of the q ∼ 0 selection rule model for the nano-Si dots is believed to be important to explain both the phenomena of peak broadening on the low-wavenumber side observed in Raman spectra and the blue shift observed in PL measurements.

  1. Understanding Environmental Tobacco Smoke Exposure and Effects in Asthmatic Children through Determination of Urinary Cotinine and Targeted Metabolomics of Plasma

    EPA Science Inventory

    Understanding Environmental Tobacco Smoke Exposure and Effects in Asthmatic Children through Determination of Urinary Cotinine and Targeted Metabolomics of Plasma Introduction Asthma is a complex disease with multiple triggers and causal factors, Exposure to environmental tob...

  2. Optimization of some laser and target features for laser-plasma interaction in the context of fusion

    NASA Astrophysics Data System (ADS)

    Depierreux, S.; Labaune, C.; Michel, D. T.; Tikhonchuk, V. T.; Tassin, V.; Stenz, C.; Borisenko, N. G.; Nazarov, W.; Grech, M.; Hüller, S.; Limpouch, J.; Loiseau, P.; Nicolaï, P.; Pesme, D.; Rozmus, W.; Meyer, C.; D-Nicola, P.; Wrobel, R.; Alozy, E.; Romary, P.; Thiell, G.; Soullié, G.; Reverdin, C.; Villette, B.; Rabec-le-Gloahec, M.; Godinho, C.

    2008-05-01

    This paper presents experimental results obtained at LULI 2000 and LIL about (i) the compared laser plasma coupling at 526 (2ω) and 351 nm (3ω) and (ii) the early laser imprint suppression using foam targets as plasma smoother of the laser beam. Both experiments are described, part of the experimental results are presented and discussed.

  3. Two-dimensional particle-in-cell plasma source ion implantation of a prolate spheroid target

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Sen; Han, Hong-Ying; Peng, Xiao-Qing; Chang, Ye; Wang, De-Zhen

    2010-03-01

    A two-dimensional particle-in-cell simulation is used to study the time-dependent evolution of the sheath surrounding a prolate spheroid target during a high voltage pulse in plasma source ion implantation. Our study shows that the potential contour lines pack more closely in the plasma sheath near the vertex of the major axis, i.e. where a thinner sheath is formed, and a non-uniform total ion dose distribution is incident along the surface of the prolate spheroid target due to the focusing of ions by the potential structure. Ion focusing takes place not only at the vertex of the major axis, where dense potential contour lines exist, but also at the vertex of the minor axis, where sparse contour lines exist. This results in two peaks of the received ion dose, locating at the vertices of the major and minor axes of the prolate spheroid target, and an ion dose valley, staying always between the vertices, rather than at the vertex of the minor axis.

  4. Combining Real-Time fMRI Neurofeedback Training of the DLPFC with N-Back Practice Results in Neuroplastic Effects Confined to the Neurofeedback Target Region

    PubMed Central

    Sherwood, Matthew S.; Weisend, Michael P.; Kane, Jessica H.; Parker, Jason G.

    2016-01-01

    In traditional fMRI, individuals respond to exogenous stimuli and are naïve to the effects of the stimuli on their neural activity patterns. Changes arising in the fMRI signal are analyzed post-hoc to elucidate the spatial and temporal activation of brain regions associated with the tasks performed. The advent of real-time fMRI has enabled a new method to systematically alter brain activity across space and time using neurofeedback training (NFT), providing a new tool to study internally-driven processes such as neuroplasticity. In this work, we combined n-back practice with fMRI-NFT of the left dorsolateral prefrontal cortex (DLPFC) to better understand the relationship between open- and closed-loop neuromodulation. FMRI data were acquired during both traditional n-back and NFT across five imaging sessions. Region-of-interest (ROI) and voxel-wise 2 × 2 within subjects ANOVAs were carried out to determine the effects of, and interaction between, training session and neuromodulation type. A main effect of training session was identified for only a single, highly focused cluster that shared spatial properties with the fMRI-NFT target region (left DLPFC). This finding indicates that combined open- and closed-loop neuroplastic enhancement techniques result in focal changes that are confined to the target area of NFT, and do not affect up- or down-stream network components that are normally engaged during working memory. Additionally, we identified a main effect of neuromodulation type for 15 clusters with significantly different activation between open- and closed-loop neuromodulation during training, 12 of which demonstrated higher activity during the open-loop neuromodulation. Our results, taken together with previous reports, indicate that fMRI-NFT combined with n-back practice leads to a highly focal volume exhibiting neuroplasticity without additional network effects. PMID:27445733

  5. Improved Confinement due to Open Ergodic Field Lines Imposed by the Dynamic Ergodic Divertor in TEXTOR

    NASA Astrophysics Data System (ADS)

    Finken, K. H.; Abdullaev, S. S.; Jakubowski, M. W.; de Bock, M. F. M.; Bozhenkov, S.; Busch, C.; von Hellermann, M.; Jaspers, R.; Kikuchi, Y.; Krämer-Flecken, A.; Lehnen, M.; Schega, D.; Schmitz, O.; Spatschek, K. H.; Unterberg, B.; Wingen, A.; Wolf, R. C.; Zimmermann, O.

    2007-02-01

    The ergodization of the magnetic field lines imposed by the dynamic ergodic diverter (DED) in TEXTOR can lead both to confinement improvement and to confinement deterioration. The cases of substantial improvement are in resonant ways related to particular conditions in which magnetic flux tubes starting at the X points of induced islands are connected with the wall. This opening process is connected with a characteristic modification of the heat deposition pattern at the divertor target plate and leads to a substantial increase and steepening of the core plasma density and pressure. The improvement is tentatively attributed to a modification of the electric potential in the plasma carried by the open field lines. The confinement improvement bases on a spontaneous density built up due to the application of the DED and is primarily a particle confinement improvement.

  6. Laser acceleration of protons using multi-ion plasma gaseous targets

    SciTech Connect

    Liu, Tung -Chang; Shao, Xi; Liu, Chuan -Sheng; Eliasson, Bengt; W. T. Hill, III; Wang, Jyhpyng; Chen, Shih -Hung

    2015-02-01

    We present a theoretical and numerical study of a novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO₂ laser pulse with a wavelength of 10 μm—much greater than that of a Ti: Sapphire laser—the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such a laser beam on a carbon–hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with a peak power of 70 TW and a pulse duration of 150 wave periods.

  7. Laser acceleration of protons using multi-ion plasma gaseous targets

    DOE PAGESBeta

    Liu, Tung -Chang; Shao, Xi; Liu, Chuan -Sheng; Eliasson, Bengt; W. T. Hill, III; Wang, Jyhpyng; Chen, Shih -Hung

    2015-02-01

    We present a theoretical and numerical study of a novel acceleration scheme by applying a combination of laser radiation pressure and shielded Coulomb repulsion in laser acceleration of protons in multi-species gaseous targets. By using a circularly polarized CO₂ laser pulse with a wavelength of 10 μm—much greater than that of a Ti: Sapphire laser—the critical density is significantly reduced, and a high-pressure gaseous target can be used to achieve an overdense plasma. This gives us a larger degree of freedom in selecting the target compounds or mixtures, as well as their density and thickness profiles. By impinging such amore » laser beam on a carbon–hydrogen target, the gaseous target is first compressed and accelerated by radiation pressure until the electron layer disrupts, after which the protons are further accelerated by the electron-shielded carbon ion layer. An 80 MeV quasi-monoenergetic proton beam can be generated using a half-sine shaped laser beam with a peak power of 70 TW and a pulse duration of 150 wave periods.« less

  8. A conserved polybasic domain mediates plasma membrane targeting of Lgl and its regulation by hypoxia.

    PubMed

    Dong, Wei; Zhang, Xuejing; Liu, Weijie; Chen, Yi-jiun; Huang, Juan; Austin, Erin; Celotto, Alicia M; Jiang, Wendy Z; Palladino, Michael J; Jiang, Yu; Hammond, Gerald R V; Hong, Yang

    2015-10-26

    Lethal giant larvae (Lgl) plays essential and conserved functions in regulating both cell polarity and tumorigenesis in Drosophila melanogaster and vertebrates. It is well recognized that plasma membrane (PM) or cell cortex localization is crucial for Lgl function in vivo, but its membrane-targeting mechanisms remain poorly understood. Here, we discovered that hypoxia acutely and reversibly inhibits Lgl PM targeting through a posttranslational mechanism that is independent of the well-characterized atypical protein kinase C (aPKC) or Aurora kinase-mediated phosphorylations. Instead, we identified an evolutionarily conserved polybasic (PB) domain that targets Lgl to the PM via electrostatic binding to membrane phosphatidylinositol phosphates. Such PB domain-mediated PM targeting is inhibited by hypoxia, which reduces inositol phospholipid levels on the PM through adenosine triphosphate depletion. Moreover, Lgl PB domain contains all the identified phosphorylation sites of aPKC and Aurora kinases, providing a molecular mechanism by which phosphorylations neutralize the positive charges on the PB domain to inhibit Lgl PM targeting. PMID:26483556

  9. A conserved polybasic domain mediates plasma membrane targeting of Lgl and its regulation by hypoxia

    PubMed Central

    Dong, Wei; Zhang, Xuejing; Liu, Weijie; Chen, Yi-jiun; Huang, Juan; Austin, Erin; Celotto, Alicia M.; Jiang, Wendy Z.; Palladino, Michael J.; Jiang, Yu; Hammond, Gerald R.V.

    2015-01-01

    Lethal giant larvae (Lgl) plays essential and conserved functions in regulating both cell polarity and tumorigenesis in Drosophila melanogaster and vertebrates. It is well recognized that plasma membrane (PM) or cell cortex localization is crucial for Lgl function in vivo, but its membrane-targeting mechanisms remain poorly understood. Here, we discovered that hypoxia acutely and reversibly inhibits Lgl PM targeting through a posttranslational mechanism that is independent of the well-characterized atypical protein kinase C (aPKC) or Aurora kinase–mediated phosphorylations. Instead, we identified an evolutionarily conserved polybasic (PB) domain that targets Lgl to the PM via electrostatic binding to membrane phosphatidylinositol phosphates. Such PB domain–mediated PM targeting is inhibited by hypoxia, which reduces inositol phospholipid levels on the PM through adenosine triphosphate depletion. Moreover, Lgl PB domain contains all the identified phosphorylation sites of aPKC and Aurora kinases, providing a molecular mechanism by which phosphorylations neutralize the positive charges on the PB domain to inhibit Lgl PM targeting. PMID:26483556

  10. Multifunctional Transmembrane Protein Ligands for Cell-Specific Targeting of Plasma Membrane-Derived Vesicles.

    PubMed

    Zhao, Chi; Busch, David J; Vershel, Connor P; Stachowiak, Jeanne C

    2016-07-01

    Liposomes and nanoparticles that bind selectively to cell-surface receptors can target specific populations of cells. However, chemical conjugation of ligands to these particles is difficult to control, frequently limiting ligand uniformity and complexity. In contrast, the surfaces of living cells are decorated with highly uniform populations of sophisticated transmembrane proteins. Toward harnessing cellular capabilities, here it is demonstrated that plasma membrane vesicles (PMVs) derived from donor cells can display engineered transmembrane protein ligands that precisely target cells on the basis of receptor expression. These multifunctional targeting proteins incorporate (i) a protein ligand, (ii) an intrinsically disordered protein spacer to make the ligand sterically accessible, and (iii) a fluorescent protein domain that enables quantification of the ligand density on the PMV surface. PMVs that display targeting proteins with affinity for the epidermal growth factor receptor (EGFR) bind at increasing concentrations to breast cancer cells that express increasing levels of EGFR. Further, as an example of the generality of this approach, PMVs expressing a single-domain antibody against green fluorescence protein (eGFP) bind to cells expressing eGFP-tagged receptors with a selectivity of ≈50:1. The results demonstrate the versatility of PMVs as cell targeting systems, suggesting diverse applications from drug delivery to tissue engineering. PMID:27294846

  11. Compression of a spherically symmetric deuterium-tritium plasma liner onto a magnetized deuterium-tritium target

    NASA Astrophysics Data System (ADS)

    Santarius, J. F.

    2012-07-01

    Converging plasma jets may be able to reach the regime of high energy density plasmas (HEDP). The successful application of plasma jets to magneto-inertial fusion (MIF) would heat the plasma by fusion products and should increase the plasma energy density. This paper reports the results of using the University of Wisconsin's 1-D Lagrangian, radiation-hydrodynamics, fusion code BUCKY to investigate two MIF converging plasma jet test cases originally analyzed by Samulyak et al. [Physics of Plasmas 17, 092702 (2010)]. In these cases, 15 cm or 5 cm radially thick deuterium-tritium (DT) plasma jets merge at 60 cm from the origin and converge radially onto a DT target magnetized to 2 T and of radius 5 cm. The BUCKY calculations reported here model these cases, starting from the time of initial contact of the jets and target. Compared to the one-temperature Samulyak et al. calculations, the one-temperature BUCKY results show similar behavior, except that the plasma radius remains about twice as long near maximum compression. One-temperature and two-temperature BUCKY results differ, reflecting the sensitivity of the calculations to timing and plasma parameter details, with the two-temperature case giving a more sustained compression.

  12. Comparative study of radiation emission without and with target in a 2.2 kJ plasma focus device

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-24

    The radiation emission in a 2.2 kJ Mather-type dense plasma focus device is investigated using a five channel BPX65 PIN diode spectrometer. Estimated X-ray associated with the hollow anode without and with target in Argon gas medium is compared. At optimum conditions, the radiation emission from the system is found to be strongly influenced with target in hollow anode and the filling gas pressure. The maximum X-ray yield in 4π sr was obtained in case of hollow anode in argon gas medium with target 'Lead' due to interaction of electron beam. Results indicated that an appropriate design of hollow anode with target could enhance the radiation emission by more intense interaction of expected electron beam with target. The outcomes are helpful in designing a plasma focus with enhanced X-ray radiation with improved shot to shot reproducibility in plasma focus device.

  13. Comparative study of radiation emission without and with target in a 2.2 kJ plasma focus device

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-01

    The radiation emission in a 2.2 kJ Mather-type dense plasma focus device is investigated using a five channel BPX65 PIN diode spectrometer. Estimated X-ray associated with the hollow anode without and with target in Argon gas medium is compared. At optimum conditions, the radiation emission from the system is found to be strongly influenced with target in hollow anode and the filling gas pressure. The maximum X-ray yield in 4π sr was obtained in case of hollow anode in argon gas medium with target "Lead" due to interaction of electron beam. Results indicated that an appropriate design of hollow anode with target could enhance the radiation emission by more intense interaction of expected electron beam with target. The outcomes are helpful in designing a plasma focus with enhanced X-ray radiation with improved shot to shot reproducibility in plasma focus device.

  14. Association between plasma selenium level and NRF2 target genes expression in humans.

    PubMed

    Reszka, Edyta; Wieczorek, Edyta; Jablonska, Ewa; Janasik, Beata; Fendler, Wojciech; Wasowicz, Wojciech

    2015-04-01

    Animal studies in rodent and in vitro studies indicate compensatory role of nuclear factor (erythroid-derived 2)-like (Nrf2) and Nrf2-regulated antioxidant and phase II biotransformation enzymes for the dietary selenium (Se) deficiency or for the loss of selenoproteins. To explore associations between plasma Se level and NRF2-regulated cytoprotective genes expression, an observational study was conducted in a population of 96 healthy non-smoking men living in Central Poland aged 18-83 years with relatively low plasma Se level. NRF2, KEAP2, CAT, EPHX1, GCLC, GCLM, GPX2, GSR, GSTA1, GSTM1, GSTP1, GSTT1, HMOX1, NQO1, PRDX1, SOD1, SOD2, TXNRD1 transcript levels in peripheral blood leukocytes and polymorphism of NRF2-617C/A (rs6721961) in blood genomic DNA were determined by means of quantitative real-time PCR. Mean plasma Se level was found to be 51.10±15.25μg/L (range 23.86-96.18μg/L). NRF2 mRNA level was positively correlated with expression of investigated NRF2-target genes. The multivariate linear regression adjusting for selenium status showed that plasma Se level was significantly inversely associated only with expression of GSTP1 (β-coef.=-0.270, p=0.009), PRDXR1 (β-coef.=-0.245, p=0.017) and SOD2 with an inverse trend toward significance (β-coef.=-0.186, p=0.074), but without an effect of NRF2 gene variants. NRF2 expression was inversely associated with age (r=-0.23, p=0.03) and body mass index (r=-0.29, p<0.001). The findings may suggest a possible link between plasma Se level and cytoprotective response at gene level in humans. PMID:25524402

  15. Enhanced relativistic laser-plasma coupling utilizing laser-induced micromodified target

    NASA Astrophysics Data System (ADS)

    Ivanov, K. A.; Brantov, A. V.; Kudryashov, S. I.; Makarov, S. V.; Gozhev, D. A.; Volkov, R. V.; Ionin, A. A.; Bychenkov, V. Yu; Savel'ev, A. B.

    2015-04-01

    The interaction of slighly relativistic femtosecond laser radiation with microstructured Si targets was studied. The microstructuring was performed by nanosecond pulse laser ablation with additional chemical etching of the target material. An analysis was made of the optical damage under the action of femtosecond radiation near the ablation threshold. It was experimentally demonstrated that the hot electron temperature increases appreciably in the laser-driven plasma (from ~370 to almost 500 keV) as well as radiation yield in the MeV range at the interaction of a high power femtosecond laser pulse with a microstructured surface in comparison with a flat surface. Numerical simulations using 3D3V PIC code Mandor revealed that the charged particle energy growth is caused by the stochastic motion of electrons in the complex field formed by the laser field and the quasistatic field at the sharp tips of micromodifications.

  16. Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas

    SciTech Connect

    Mao, J. Y.; Chen, L. M.; Huang, K.; Ma, Y.; Zhao, J. R.; Yan, W. C.; Ma, J. L.; Wei, Z. Y.; Li, D. Z.; Aeschlimann, M.; Zhang, J.

    2015-03-30

    Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-critical-density preplasma. It reveals that a bubble-like structure as an accelerating cavity appears in the near-critical-density plasma region and travels along the target surface. A bunch of electrons are pinched transversely and accelerated longitudinally by the wake field in the bubble. The outstanding normalized emittance and monochromaticity of such highly collimated surface electron beams could make it an ideal beam for fast ignition or may serve as an injector in traditional accelerators.

  17. Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas

    NASA Astrophysics Data System (ADS)

    Mao, J. Y.; Chen, L. M.; Huang, K.; Ma, Y.; Zhao, J. R.; Li, D. Z.; Yan, W. C.; Ma, J. L.; Aeschlimann, M.; Wei, Z. Y.; Zhang, J.

    2015-03-01

    Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-critical-density preplasma. It reveals that a bubble-like structure as an accelerating cavity appears in the near-critical-density plasma region and travels along the target surface. A bunch of electrons are pinched transversely and accelerated longitudinally by the wake field in the bubble. The outstanding normalized emittance and monochromaticity of such highly collimated surface electron beams could make it an ideal beam for fast ignition or may serve as an injector in traditional accelerators.

  18. X-Ray Modeling of Very Young Early-Type Stars in the Orion Trapezium: Signatures of Magnetically Confined Plasmas and Evolutionary Implications

    NASA Astrophysics Data System (ADS)

    Schulz, N. S.; Canizares, C.; Huenemoerder, D.; Tibbets, K.

    2003-09-01

    The Orion Trapezium is one of the youngest and closest star-forming regions within our Galaxy. With a dynamic age of ~3×105 yr, it harbors a number of very young hot stars, which likely are on the zero-age main sequence (ZAMS). We analyzed high-resolution X-ray spectra in the wavelength range of 1.5-25 Å of three of its X-ray-brightest members (Θ1 Ori A, C, and E) obtained with the High Energy Transmission Grating Spectrometer (HETGS) on board the Chandra X-Ray Observatory. We measured X-ray emission lines, calculated differential emission measure distributions (DEMs), and fitted broadband models to the spectra. The spectra from all three stars are very rich in emission lines, specifically from highly ionized Fe, which includes emission from Fe XVII to Fe XXV ions. A complete line list is included. This is a mere effect of high temperatures rather than an overabundance of Fe, which in fact turns out to be underabundant in all three Trapezium members. Similarly there is a significant underabundance in Ne and O as well, whereas Mg, Si, S, Ar, and Ca appear close to solar. The DEM derived from over 80 emission lines in the spectrum of Θ1 Ori C indicates three peaks located at 7.9, 25, and 66 MK. The emission measure varies over the 15.4 day wind period of the star. For the two phases observed, the low-temperature emission remains stable, while the high-temperature emission shows significant differences. The line widths seem to show a similar bifurcation, where we resolve some of the soft X-ray lines with velocities up to 850 km s-1 (all widths are stated as half-width at half-maximum), whereas the bulk of the lines remain unresolved with a confidence limit of 110 km s-1. The broadband spectra of the other two stars can be fitted with several collisionally ionized plasma model components within a temperature range of 4.3-46.8 MK for Θ1 Ori E and 4.8-42.7 MK for Θ1 Ori A. The high-temperature emissivity contributes over 70% to the total X-ray flux. None of the

  19. Enhancement of confinement in tokamaks

    SciTech Connect

    Furth, H.P.

    1986-05-01

    A plausible interpretation of the experimental evidence is that energy confinement in tokamaks is governed by two separate considerations: (1) the need for resistive MHD kink-stability, which limits the permissible range of current profiles - and therefore normally also the range of temperature profiles; and (2) the presence of strongly anomalous microscopic energy transport near the plasma edge, which calibrates the amplitude of the global temperature profile, thus determining the energy confinement time tau/sub E/. Correspondingly, there are two main paths towards the enhancement of tokamak confinement: (1) Configurational optimization, to increase the MHD-stable energy content of the plasma core, can evidently be pursued by varying the cross-sectional shape of the plasma and/or finding stable radial profiles with central q-values substantially below unity - but crossing from ''first'' to ''second'' stability within the peak-pressure region would have the greatest ultimate potential. (2) Suppression of edge turbulence, so as to improve the heat insulation in the outer plasma shell, can be pursued by various local stabilizing techniques, such as use of a poloidal divertor. The present confinement model and initial TFTR pellet-injection results suggest that the introduction of a super-high-density region within the plasma core should be particularly valuable for enhancing ntau/subE/. In D-T operation, a centrally peaked plasma pressure profile could possibly lend itself to alpha-particle-driven entry into the second-stability regime.

  20. A targeted proteomics–based pipeline for verification of biomarkers in plasma

    PubMed Central

    Whiteaker, Jeffrey R; Lin, Chenwei; Kennedy, Jacob; Hou, Liming; Trute, Mary; Sokal, Izabela; Yan, Ping; Schoenherr, Regine M; Zhao, Lei; Voytovich, Uliana J; Kelly-Spratt, Karen S; Krasnoselsky, Alexei; Gafken, Philip R; Hogan, Jason M; Jones, Lisa A; Wang, Pei; Amon, Lynn; Chodosh, Lewis A; Nelson, Peter S; McIntosh, Martin W; Kemp, Christopher J; Paulovich, Amanda G

    2011-01-01

    High-throughput technologies can now identify hundreds of candidate protein biomarkers for any disease with relative ease. However, because there are no assays for the majority of proteins and de novo immunoassay development is prohibitively expensive, few candidate biomarkers are tested in clinical studies. We tested whether the analytical performance of a biomarker identification pipeline based on targeted mass spectrometry would be sufficient for data-dependent prioritization of candidate biomarkers, de novo development of assays and multiplexed biomarker verification. We used a data-dependent triage process to prioritize a subset of putative plasma biomarkers from >1,000 candidates previously identified using a mouse model of breast cancer. Eighty-eight novel quantitative assays based on selected reaction monitoring mass spectrometry were developed, multiplexed and evaluated in 80 plasma samples. Thirty-six proteins were verified as being elevated in the plasma of tumor-bearing animals. The analytical performance of this pipeline suggests that it should support the use of an analogous approach with human samples. PMID:21685906