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Sample records for mev neutral beam

  1. Charge neutralized low energy beam transport at Brookhaven 200 MeV linac

    SciTech Connect

    Raparia, D. Alessi, J.; Atoian, G.; Zelenski, A.

    2016-02-15

    The H{sup −} magnetron source provides about 100 mA H{sup −} beam to be match into the radio-frequency quadrupole accelerator. As H{sup −} beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H{sup −} beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H{sup −} beam from optically pumped polarized ion source.

  2. New source of MeV negative ion and neutral atom beams

    SciTech Connect

    Ter-Avetisyan, S.; Braenzel, J.; Schnürer, M.; Prasad, R.; Borghesi, M.; Jequier, S.; Tikhonchuk, V.

    2016-02-15

    The scenario of “electron-capture and -loss” was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities.

  3. ALEX neutral beam probe

    SciTech Connect

    Pourrezaei, K.

    1982-01-01

    A neutral beam probe capable of measuring plasma space potential in a fully 3-dimensional magnetic field geometry has been developed. This neutral beam was successfully used to measure an arc target plasma contained within the ALEX baseball magnetic coil. A computer simulation of the experiment was performed to refine the experimental design and to develop a numerical model for scaling the ALEX neutral beam probe to other cases of fully 3-dimensional magnetic field. Based on this scaling a 30 to 50 keV neutral cesium beam probe capable of measuring space potential in the thermal barrier region of TMX Upgrade was designed.

  4. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, W.K.

    1984-05-29

    The neutral beam intensity controller is based on selected magnetic defocusing of the ion beam prior to neutralization. The defocused portion of the beam is dumped onto a beam dump disposed perpendicular to the beam axis. Selective defocusing is accomplished by means of a magnetic field generator disposed about the neutralizer so that the field is transverse to the beam axis. The magnetic field intensity is varied to provide the selected partial beam defocusing of the ions prior to neutralization. The desired focused neutral beam portion passes along the beam path through a defining aperture in the beam dump, thereby controlling the desired fraction of neutral particles transmitted to a utilization device without altering the kinetic energy level of the desired neutral particle fraction. By proper selection of the magnetic field intensity, virtually zero through 100% intensity control of the neutral beam is achieved.

  5. Neutral particle beam intensity controller

    DOEpatents

    Dagenhart, William K.

    1986-01-01

    A neutral beam intensity controller is provided for a neutral beam generator in which a neutral beam is established by accelerating ions from an ion source into a gas neutralizer. An amplitude modulated, rotating magnetic field is applied to the accelerated ion beam in the gas neutralizer to defocus the resultant neutral beam in a controlled manner to achieve intensity control of the neutral beam along the beam axis at constant beam energy. The rotating magnetic field alters the orbits of ions in the gas neutralizer before they are neutralized, thereby controlling the fraction of neutral particles transmitted out of the neutralizer along the central beam axis to a fusion device or the like. The altered path or defocused neutral particles are sprayed onto an actively cooled beam dump disposed perpendicular to the neutral beam axis and having a central open for passage of the focused beam at the central axis of the beamline. Virtually zero therough 100% intensity control is achieved by varying the magnetic field strength without altering the ion source beam intensity or its species yield.

  6. Neutral beam injection system

    SciTech Connect

    Duesing, G.; Altmann, H.; Falter, H.; Goede, A.; Haange, R.; Hemsworth, R.S.; Kupschus, P.; Stork, D.; Thompson, E.

    1987-01-01

    The development of the neutral injection (NI) system for the Joint European Torus and its status in 1985 are reported. First the system parameters are discussed and the layout is described, followed by a summary of the physics design calculations, the development, production, and testing of the components and the subsystem assembly. The system commissioning is presented, including a description of the function and the realization of the NI test bed. A summary of performance predictions for 80-keV beam heating experiments, and of the experimental evidence on balanced versus coinjection, is presented. The operational experience with the first injector and the plasma physics results obtained so far are summarized.

  7. Neutral Particle Beam Popup Applications

    DTIC Science & Technology

    1991-03-01

    LA-11785-MS Neutral Particle Beam Popup Applications PI ApPDi.stnbulion Un^ d PLEASE RETURN TO: BMO TECHNICAL INFORMATION CENTER BALLISTIC...California, the United States Government, or any agency thereof. Accession Number: 3027 Publication Date: Mar 01, 1991 Title: Neutral Particle Beam Popup...11785-MS Report Prepared for: U.S. Dept. of Energy Descriptors, Keywords: NPB Neutral Particle Beam Application Threat Decoy Discrimination Deployment

  8. BEAMS3D Neutral Beam Injection Model

    SciTech Connect

    Lazerson, Samuel

    2014-04-14

    With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

  9. Photodetachment process for beam neutralization

    DOEpatents

    Fink, Joel H. [Livermore, CA; Frank, Alan M. [Livermore, CA

    1979-02-20

    A process for neutralization of accelerated ions employing photo-induced charge detachment. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process.

  10. Photodetachment process for beam neutralization

    DOEpatents

    Fink, J.H.; Frank, A.M.

    1979-02-20

    A process for neutralization of accelerated ions employing photo-induced charge detachment is disclosed. The process involves directing a laser beam across the path of a negative ion beam such as to effect photodetachment of electrons from the beam ions. The frequency of the laser beam employed is selected to provide the maximum cross-section for the photodetachment process. 2 figs.

  11. NEUTRAL-BEAM INJECTION

    SciTech Connect

    Kunkel, W.B.

    1980-06-01

    The emphasis in the preceding chapters has been on magnetic confinement of high temperature plasmas. The question of production and heating of such plasmas has been dealt with relatively more briefly. It should not be inferred, however, that these matters must therefore be either trivial or unimportant. A review of the history reveals that in the early days all these aspects of the controlled fusion problem were considered to be on a par, and were tackled simultaneously and with equal vigor. Only the confinement problem turned out to be much more complex than initially anticipated, and richer in challenge to the plasma physicist than the questions of plasma production and heating. On the other hand, the properties of high-temperature plasmas and plasma confinement can only be studied experimentally after the problems of production and of heating to adequate temperatures are solved. It is the purpose of this and the next chapter to supplement the preceding discussions with more detail on two important subjects: neutral-beam injection and radio-frequency heating. These are the major contenders for heating in present and future tokamak and mirror fusion experiments, and even in several proposed reactors. For neutral beams we emphasize here the technology involved, which has undergone a rather remarkable development. The physics of particle and energy deposition in the plasma, and the discussion of the resulting effects on the confined plasma, have been included in previous chapters, and some experimental results are quoted there. Other heating processes of relevance to fusion are mentioned elsewhere in this book, in connection with the experiments where they are used: i.e. ohmic heating, adiabatic compression heating, and alpha-particle heating in Chapter 3 by H.P. Furth; more ohmic heating in Chapter 7, and shock-implosion heating, laser heating, and relativistic-electron beam heating in Chapter 8, both by W. E. Quinn. These methods are relatively straightforward in

  12. BEAMS3D Neutral Beam Injection Model

    NASA Astrophysics Data System (ADS)

    McMillan, Matthew; Lazerson, Samuel A.

    2014-09-01

    With the advent of applied 3D fields in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous slowing down, and pitch angle scattering are modeled with the ADAS atomic physics database. Elementary benchmark calculations are presented to verify the collisionless particle orbits, NBI model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields. Notice: this manuscript has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

  13. ITER neutral beam system US conceptual design

    SciTech Connect

    Purgalis, P.

    1990-09-01

    In this document we present the US conceptual design of a neutral beam system for International Thermonuclear Experimental Reactor (ITER). The design incorporates a barium surface conversion D{sup {minus}} source feeding a linear array of accelerator channels. The system uses a dc accelerator with electrostatic quadrupoles for strong focusing. A high voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and in the ion dump cavity to pump re-neutralized ions and neutralizer gas. All the above components are packaged in compact identical, independent modules which can be removed for remote maintenance. The neutral beam system delivers 75 MW of DO at 1.3 MeV, into three ports with a total of 9 modules arranged in stacks of three modules per port . To increase reliability each module is designed to deliver up to 10 MW; this allows eight modules operating at partial capacity to deliver the required power in the event one module is out of service, and provides 20% excess capacity to improve availability. Radiation protection is provided by shielding and by locating critical components in the source and accelerator 46.5 m from the torus centerline. Neutron shielding in the drift duct and neutralizer provides the added feature of limiting conductance and thus reducing gas flow to and from the torus.

  14. A high energy neutral beam system for reactors

    SciTech Connect

    Anderson, O.A.; Chan, C.F.; Cooper, W.S.; Leung, K.N.; Lietzke, A.F.; Kim, C.H.; Kunkel, W.B.; Kwan, J.W.; Purgalis, P.; Schlachter, A.S.

    1988-09-01

    High energy neutral beams provide a promising method of heating and driving current in steady-state tokamak fusion reactors. As an example, we have made a conceptual design of a neutral beam system for current drive on the International Thermonuclear Experimental Reactor (ITER). The system, based on electrostatic acceleration of D/sup /minus// ions, can deliver up to 100 MW of 1.6 MeV D/sup 0/ neutrals through three ports. Radiation protection is provided by locating sensitive beamline components 35 to 50 m from the reactor. In an application to a 3300 MW power reactor, a system delivering 120 MW of 2-2.4 MeV deuterium beams assisted by 21 MW of lower hybrid wave power drives 25 MA and provides an adequate plasma power gain (Q = 24) for a commercial fusion power plant. 8 refs., 1 fig., 2 tabs.

  15. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  16. Plasma/Neutral-Beam Etching Apparatus

    NASA Technical Reports Server (NTRS)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  17. Ion-beam Plasma Neutralization Interaction Images

    SciTech Connect

    Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

    2002-04-09

    Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented.

  18. EDITORIAL: Negative ion based neutral beam injection

    NASA Astrophysics Data System (ADS)

    Hemsworth, R. S.

    2006-06-01

    It is widely recognized that neutral beam injection (NBI), i.e. the injection of high energy, high power, beams of H or D atoms, is a flexible and reliable system that has been the main heating system on a large variety of fusion devices, and NBI has been chosen as one of the three heating schemes of the International Tokomak Reactor (ITER). To date, all the NBI systems but two have been based on the neutralization (in a simple gas target) of positive hydrogen or deuterium ions accelerated to <100 keV/nucleon. Above that energy the neutralization of positive ions falls to unacceptably low values, and higher energy neutral beams have to be created by the neutralization of accelerated negative ions (in a simple gas target), as this remains high (approx60%) up to >1 MeV/nucleon. Unfortunately H- and D- are difficult to create, and the very characteristic that makes them attractive, the ease with which the electron is detached from the ion, means that it is difficult to create high concentrations or fluxes of them, and it is difficult to avoid substantial, collisional, losses in the extraction and acceleration processes. However, there has been impressive progress in negative ion sources and accelerators over the past decade, as demonstrated by the two pioneering, operational, multi-megawatt, negative ion based, NBI systems at LHD (180 keV, H0) and JT-60U (500 keV, D0), both in Japan. Nevertheless, the system proposed for ITER represents a substantial technological challenge as an increase is required in beam energy, to 1 MeV, D0, accelerated ion (D-) current, to 40 A, accelerated current density, 200 A m-2 of D-, and pulse length, to 1 h. At the Fourth IAEA Technical Meeting on Negative Ion Based Neutral Beam Injectors, hosted by the Consorzio RFX, Padova, Italy, 9-11 May 2005, the status of the R&D aimed at the realization of the injectors for ITER was presented. Because of the importance of this development to the success of the ITER project, participants at that

  19. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Wang, Joseph

    2010-05-21

    Ion beam emission/neutralization is one of the most fundamental problems in spacecraft plasma interactions and electric propulsion. Although ion beam neutralization is readily achieved in experiments, the understanding of the underlying physical process remains at a rather primitive level. No theoretical or simulation models have convincingly explained the detailed neutralization mechanism, and no conclusions have been reached. This paper presents a fully kinetic simulation of ion beam neutralization and plasma beam propagation and discusses the physics of electron-ion coupling and the resulting propagation of a neutralized mesothermal plasma.

  20. 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.

  1. Neutral-beam current drive in tokamaks

    SciTech Connect

    Devoto, R.S.

    1986-01-01

    The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500 to 700 keV are needed for this device.

  2. Acceleration of ampere class H(-) ion beam by MeV accelerator.

    PubMed

    Taniguchi, M; Inoue, T; Umeda, N; Kashiwagi, M; Watanabe, K; Tobari, H; Dairaku, M; Sakamoto, K

    2008-02-01

    The H(-) ion accelerator R&D to realize the international thermonuclear experimental reactor neutral beam is ongoing at Japan Atomic Energy Agency (JAEA). The required performance for the prototype MeV accelerator developed at JAEA is 1 MeV, 500 mA (current density of 200 A/m(2)) H(-) ion beam at the beamlet divergence angle of less than 7 mrad. Up to 2005, 836 keV, 146 A/m(2) H(-) ion beam was successfully accelerated as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 3 x 3 (9 apertures) to 3 x 5 (15 apertures). By fixing the air leak at the source chamber due to backstream ions as well as the improvement of voltage holding capability by a new fiber reinforced plastic insulator ring, the performance of the MeV accelerator was improved. So far, H(-) ion beam of 320 mA was successfully accelerated up to 796 keV with the beam divergence angle of 5.5 mrad. The accelerated drain current including the electron reaches close to the power supply limit for the MeV test facility. The heat flux by the backstream ion during the above beam acceleration was estimated to be 360 W/cm(2). The Cs leakage to the accelerator during the test campaign (Cs total input of 5.0 g) was 0.26 mg (7.0 microg/cm(2)). This is considered to be the allowable level from the viewpoint of voltage holding.

  3. Beam diagnostics for the Fermilab 400 meV Linac

    SciTech Connect

    McCrory, E. )

    1992-07-10

    The Fermilab 200 MeV Linac is scheduled to be upgraded to a 400 MeV Linac beginning in the Spring of 1993 [1]. We have designed beam diagnostics for the accelerator to expedite the commissioning and to facilitate the long-term reliability of the machine. These diagnostics include: stripline beam position monitors, resistive wall-current monitors, X-Y-U wire scanners, and various velocity and/or phase measurement devices, including bucnh-length detectors fashioned after the work at the INR in Moscow [2]. This paper will discuss these devices and our plans fot the commissioning of the new Linac using these diagnostics.

  4. Neutral particle beams for space defense

    NASA Astrophysics Data System (ADS)

    Botwin, Robert; Favale, Anthony

    Neutral particle beam (NPB) weapons direct highly focused high energy streams of electrically neutral atomic particles traveling at nearly the speed of light, escaping deflection from the earth's magnetic field and acting on the subatomic structure of a target, destroying it from within. The beam's brief contact with a reentry vehicle produces a nuclear reaction in the latter that yields particle emissions; by detecting and identifying those particles, it becomes possible to effectively distinguish warheads from decoys. Attention is given to the NPB program roles to be played by the Beam Experiment Aboard Rocket and Neutral Particle Beam Integrated Space Experiment projects.

  5. Neutron measurements from beam-target reactions at the ELISE neutral beam test facility

    SciTech Connect

    Xufei, X. Fan, T.; Nocente, M.; Gorini, G.; Bonomo, F.; Franzen, P.; Fröschle, M.; Grosso, G.; Tardocchi, M.; Grünauer, F.; Pasqualotto, R.

    2014-11-15

    Measurements of 2.5 MeV neutron emission from beam-target reactions performed at the ELISE neutral beam test facility are presented in this paper. The measurements are used to study the penetration of a deuterium beam in a copper dump, based on the observation of the time evolution of the neutron counting rate from beam-target reactions with a liquid scintillation detector. A calculation based on a local mixing model of deuterium deposition in the target up to a concentration of 20% at saturation is used to evaluate the expected neutron yield for comparison with data. The results are of relevance to understand neutron emission associated to beam penetration in a solid target, with applications to diagnostic systems for the SPIDER and MITICA Neutral Beam Injection prototypes.

  6. An autoneutralizing neutral molecular beam gun

    NASA Astrophysics Data System (ADS)

    Delmore, J. E.; Appelhans, A. D.; Dahl, D. A.

    1990-01-01

    A high-energy (up to 28 keV) neutral molecular beam gun has been developed and put into routine use that takes advantage of the autoneutralization properties of the sulfur hexafluoride anion for the production of high-energy sulfur hexafluoride neutral molecules. The anions are produced in an electron-capture source, accelerated, and focused in a lens assembly designed to minimize residence time, allowed to drift at their terminal velocity for a suitable distance during which up to 30% auto-eject an electron, and all remaining charged particles are electrostatically skimmed, resulting in a focused neutral beam. Rasterable neutral beams focused to a 5-mm spot size up to 3 m from the source have been produced with beam currents up to 40 pA equivalent. Spot sizes of 1 mm can be produced with intensity levels of a few picoamperes equivalent.

  7. Kinetic Simulations of Ion Beam Neutralization

    SciTech Connect

    Chang, O.; Wang, J.

    2011-05-20

    Full particle PIC simulations are performed to study the neutralization of an ion beam in the cohesionless, mesothermal regime. Simulations further confirmed that neutralization is achieved through interactions between the trapped electrons and the potential well established by the propagation of the beam front along the beam direction and is not through plasma instabilities as previous studies suggested. In the transverse direction, the process is similar to that of the expansion of mesothermal plasma into vacuum. Parametric simulations are also performed to investigate the effects of beam radius and domain boundary condition on the neutralization process. The results suggests that, while the qualitative behavior may be similar in ground tests, quantitative parameters such as the beam potential will be affected significantly by the vacuum chamber because of the limits imposed on the expansion process by the finite chamber space.

  8. Neutral Beam Injection in the Electric Tokamak

    NASA Astrophysics Data System (ADS)

    Gourdain, P.-A.; Carter, T. A.; Gauvreau, J.-L.; Grossman, A.; Lafonteese, D. J.; Pace, D. C.; Schmitz, L. W.; Taylor, R. J.; White, A. E.; Yates, T. F.

    2004-11-01

    The Electric Tokamak (ET) at UCLA (Bt=0.25T, R=5m, a=1m, Te(0)=300eV, tau(0)=1s) is now running long shots (5s). A new development program was started last year to include a neutral beam in the daily operations of the machine. As a result, a 10kV neutral beam injector was built to deal with plasma and measurement issues. The design and parameters of the beam are discussed. The source is based on an RF generated plasma, with a single extraction grid providing an accel-decel configuration. Plasma neutralization efficiency is also presented. Co- or counter injection is now possible using a single beam. The construction of a second beam is planned for simultaneous co- and counter injections for toroidal momentum input control. Plasma toroidal and poloidal rotation, particle diffusion and current drive effects will be presented.

  9. Implications of tritium in neutral beam injectors

    SciTech Connect

    Kim, J; Stewart, L D

    1980-01-01

    Neutral injectors for heating plasmas of D-T burning fusion reactors are subject to tritium contamination. This paper discusses relevant questions and problem areas pertinent to tritium environment, including calculations of tritium contaminations in different neutral injectors, gas handling and pumping systems, and implications on beam line components.

  10. Semiconductor etching by hyperthermal neutral beams

    NASA Technical Reports Server (NTRS)

    Minton, Timothy K. (Inventor); Giapis, Konstantinos P. (Inventor)

    1999-01-01

    An at-least dual chamber apparatus and method in which high flux beams of fast moving neutral reactive species are created, collimated and used to etch semiconductor or metal materials from the surface of a workpiece. Beams including halogen atoms are preferably used to achieve anisotropic etching with good selectivity at satisfactory etch rates. Surface damage and undercutting are minimized.

  11. Diagnostics for neutral-beam-heated tokamaks

    SciTech Connect

    Goldston, R.J.

    1982-12-01

    Diagnostic techniques for neutral-beam-heated tokamak plasmas fall into three categories: (1) magnetic diagnostics for measurements of gross stored energy, (2) profile diagnostics for measurements of stored thermal and beam energy, impurity content and plasma rotation, and (3) fast time resolution diagnostics to study MHD fluctuations and micro-turbulence.

  12. TPX/TFTR Neutral Beam energy absorbers

    SciTech Connect

    Dahlgren, F.; Wright, K.; Kamperschroer, J.; Grisham, L.; Lontai, L.; Peters, C.; VonHalle, A.

    1993-11-01

    The present beam energy absorbing surfaces on the TFTR Neutral Beams such as Ion Dumps, Calorimeters, beam defining apertures, and scrapers, are simple water cooled copper plates which wee designed to absorb (via their thermal inertia) the incident beam power for two seconds with a five minute coal down interval between pulses. These components are not capable of absorbing the anticipated beam power loading for 1000 second TPX pulses and will have to be replaced with an actively cooled design. While several actively cooled energy absorbing designs were considered,, the hypervapotron elements currently being used on the JET beamlines were chosen due to their lower cooling water demands and reliable performance on JET.

  13. Neutral particle beam sensing and steering

    DOEpatents

    Maier, II, William B.; Cobb, Donald D.; Robiscoe, Richard T.

    1991-01-01

    The direction of a neutral particle beam (NPB) is determined by detecting Ly.alpha. radiation emitted during motional quenching of excited H(2S) atoms in the beam during movement of the atoms through a magnetic field. At least one detector is placed adjacent the beam exit to define an optical axis that intercepts the beam at a viewing angle to include a volume generating a selected number of photons for detection. The detection system includes a lens having an area that is small relative to the NPB area and a pixel array located in the focal plane of the lens. The lens viewing angle and area pixel array are selected to optimize the beam tilt sensitivity. In one embodiment, two detectors are placed coplanar with the beam axis to generate a difference signal that is insensitive to beam variations other than beam tilt.

  14. Efficiencies of gas neutralizers for multi-MeV beams of light negative ions

    SciTech Connect

    Grisham, L.R.; Post, D.E.; Johnson, B.M.; Jones, K.W.; Barette, J.; Kruse, T.H.; Tserruya, I.; Da-Hai, W.

    1981-11-01

    Measurements are reported of the neutral and charged particle fractions produced by running beams of Li/sup -/, C/sup -/, O/sup -/, and Si/sup -/ at energies up to 7 MeV through gas cells of N/sub 2/, Ar, or CO/sub 2/. We discuss the implications of these measurements for the design of neutralizers to produce high energy light atom beams for heating or current drive in tokamaks.

  15. Fundamentals of the fast neutral beams diagnostics

    NASA Astrophysics Data System (ADS)

    Kudrya, V.; Maishev, Yu.

    2016-12-01

    Physical principles of fast neutral beams diagnostics methods are considered. In the opening sections an analysis of the methods intended for measurement of beam composition and energy characteristics of the beam components is presented. For the high resolution Doppler spectroscopy method some relations for energy resolution are derived. For the ionization method an approach to the atomic content calculations is developed in cases of a working gas like H2, N2, O2. Further on, the secondary electron emission, calorimetric, and quartz resonator probes are considered. Dependences of the probe responses on the beam parameters are presented. The results obtained can be used for development and design of fast neutral beams diagnostics systems.

  16. Neutralizer options for high energy H/sup -/ beams

    SciTech Connect

    Fink, J.H.

    1986-10-01

    A neutralizer converts a negative ion beam into a neutral beam, but it also increases the beamline cost, weight and size while reducing its output power, efficiency and possibly the reliability of the entire system. In addition it scatters the newly formed neutrals, altering the beam current density distribution, causing the beam divergence to get larger and the brightness to go down. In the following, the role of neutralizers for hydrogen ion beams is reviewed, and the problems encountered over a range of beam energies are discussed. Consideration is given to enhancing the goals of the neutral beam application, be they the highest neutral fraction, optimum overall efficiency or maximum beam brightness, etc.

  17. Plasma Heating by Neutral Beam Injection

    SciTech Connect

    Koch, R

    2004-03-15

    The additional heating of plasmas by injection of fast neutrals - or Neutral Beam Injection (NBI) - is reviewed. First, the limitations of ohmic heating in tokamaks and the other motivations for using additional heating in fusion machines are discussed. Next, the principle of operation of neutral beam injectors, and state of the art, are outlined. Positive-ion (PNBI) and negative-ion (NNBI) based concepts are discussed. Next, the physical processes by which the beam transfers energy to the plasma, namely ionisation and slowing-down are described. For both, an elementary theory is given and the comparison with experimental results is made. Applications of NBI to heating, current drive and rotation drive are reviewed. The prospects of NBI for ITER are commented.

  18. ITER neutral beam system US conceptual design. Final vesion

    SciTech Connect

    Purgalis, P.

    1990-09-01

    In this document we present the US conceptual design of a neutral beam system for International Thermonuclear Experimental Reactor (ITER). The design incorporates a barium surface conversion D{sup {minus}} source feeding a linear array of accelerator channels. The system uses a dc accelerator with electrostatic quadrupoles for strong focusing. A high voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and in the ion dump cavity to pump re-neutralized ions and neutralizer gas. All the above components are packaged in compact identical, independent modules which can be removed for remote maintenance. The neutral beam system delivers 75 MW of DO at 1.3 MeV, into three ports with a total of 9 modules arranged in stacks of three modules per port . To increase reliability each module is designed to deliver up to 10 MW; this allows eight modules operating at partial capacity to deliver the required power in the event one module is out of service, and provides 20% excess capacity to improve availability. Radiation protection is provided by shielding and by locating critical components in the source and accelerator 46.5 m from the torus centerline. Neutron shielding in the drift duct and neutralizer provides the added feature of limiting conductance and thus reducing gas flow to and from the torus.

  19. ISX-B neutral beams and the beam target experiment

    SciTech Connect

    Bates, S.C.; Edmonds, P.H.; Kim, J.; Bush, C.E.; Massengill, L.A.; Overbey, D.R.; Pearce, J.W.

    1980-10-01

    This report describes the hardware and operation of the ISX neutral beamlines as well as an experiment done to verify estimates of the neutral power injected into the tokamak. Tangential coinjection of megawatt levels of 30 to 40-keV neutrals into the tokamak has made the study of high-beta plasmas in ISX possible. These power levels were achieved with high reliability (over 90%) by two neutral beamlines with design power ratings of 900 kW of H/sup 0/ (upgraded to 1.5 MW) each. The neutral beamlines consist of a duoPIGatron plasma generator, acceleration grids, a gas neutralization cell, an ion deflection magnet, beam calorimetry, high-speed helium cryocondensation vacuum pumps, and associated electrical and control systems. The beamlines and their operation are described briefly with an emphasis on their relation to injection into a plasma. Neutral injection geometry with respect to the tokamak is given.

  20. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    SciTech Connect

    Chrystal, C.; Burrell, K. H.; Pace, D. C.; Grierson, B. A.

    2015-10-15

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  1. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    DOE PAGES

    Chrystal, Colin; Burrell, Keith H.; Grierson, Brian A.; ...

    2015-10-20

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in-situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination diagnostic (CER) at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain informationmore » about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. Lastly, the methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.« less

  2. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission.

    PubMed

    Chrystal, C; Burrell, K H; Grierson, B A; Pace, D C

    2015-10-01

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination (CER) diagnostic at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. The methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  3. TPX Neutral Beam Injection System design

    SciTech Connect

    von Halle, A.; Bowen, O.N.; Edwards, J.W.

    1993-11-01

    The existing Tokamak Fusion Test Reactor Neutral Beam system is proposed to be modified for long pulse operation on the Tokamak Physics Experiment (TPX). Day one of TPX will call for one TFTR beamline modified for 1000 second pulse lengths oriented co-directional to the plasma current. The system design will be capable of accommodating an additional co-directional and a single counter directional beamline. For the TPX conceptual design, every attempt was made to use existing Neutral Beam hardware, plant facilities, auxiliary systems, service infrastructure, and control systems. This paper describes the moderate modifications required to the power systems, the ion sources, and the beam impinged surfaces of the ion dumps, the calorimeters, the various beam scrapers, and the neutralizers. Also described are the minimal modifications required to the vacuum, cryogenic, and gas systems and the major modification of replacing the beamline-torus duct in its entirety. Operational considerations for Neutral Beam subsystems over 1000 second pulse lengths will be explored including proposed operating scenarios for full steady state operation.

  4. Status of the ITER heating neutral beam system

    NASA Astrophysics Data System (ADS)

    Hemsworth, R.; Decamps, H.; Graceffa, J.; Schunke, B.; Tanaka, M.; Dremel, M.; Tanga, A.; DeEsch, H. P. L.; Geli, F.; Milnes, J.; Inoue, T.; Marcuzzi, D.; Sonato, P.; Zaccaria, P.

    2009-04-01

    The ITER neutral beam (NB) injectors are the first injectors that will have to operate under conditions and constraints similar to those that will be encountered in a fusion reactor. These injectors will have to operate in a hostile radiation environment and they will become highly radioactive due to the neutron flux from ITER. The injectors will use a single large ion source and accelerator that will produce 40 A 1 MeV D- beams for pulse lengths of up to 3600 s. Significant design changes have been made to the ITER heating NB (HNB) injector over the past 4 years. The main changes are: Modifications to allow installation and maintenance of the beamline components with an overhead crane. The beam source vessel shape has been changed and the beam source moved to allow more space for the connections between the 1 MV bushing and the beam source. The RF driven negative ion source has replaced the filamented ion source as the reference design. The ion source and extractor power supplies will be located in an air insulated high voltage (-1 MV) deck located outside the tokamak building instead of inside an SF6 insulated HV deck located above the injector. Introduction of an all metal absolute valve to prevent any tritium in the machine to escape into the NB cell during maintenance. This paper describes the status of the design as of December 2008 including the above mentioned changes. The very important power supply system of the neutral beam injectors is not described in any detail as that merits a paper beyond the competence of the present authors. The R&D required to realize the injectors described in this paper must be carried out on a dedicated neutral beam test facility, which is not described here.

  5. Neutral Beam Interactions with Materials.

    DTIC Science & Technology

    1985-11-22

    studies of electron beam pumped optical emission , we have performed extensive research into the problems of field- emission cathode designs for jlis...starting point for this work. The basic configuration for the initial diode experiments is depicted in Figure 1. Both carbon fiber and velvet cathodes were...2,523( 0981). 35 i 12. " Explosive emission of electrons ," S.P. Bugaev, E.A. Litvinov, G.A. Mesyats, and D.1. Proskurovskii, Sov. Phys.-Usp.,1,5 1

  6. Intense diagnostic neutral beam development for ITER

    SciTech Connect

    Rej, D.J.; Henins, I.; Fonck, R.J.; Kim, Y.J.

    1992-05-01

    For the next-generation, burning tokamak plasmas such as ITER, diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasma parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 25-kA, 100-kV, 1-{mu}s accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance.

  7. Intense diagnostic neutral beam development for ITER

    SciTech Connect

    Rej, D.J.; Henins, I. ); Fonck, R.J.; Kim, Y.J. . Dept. of Nuclear Engineering and Engineering Physics)

    1992-01-01

    For the next-generation, burning tokamak plasmas such as ITER, diagnostic neutral beams and beam spectroscopy will continue to be used to determine a variety of plasma parameters such as ion temperature, rotation, fluctuations, impurity content, current density profile, and confined alpha particle density and energy distribution. Present-day low-current, long-pulse beam technology will be unable to provide the required signal intensities because of higher beam attenuation and background bremsstrahlung radiation in these larger, higher-density plasmas. To address this problem, we are developing a short-pulse, intense diagnostic neutral beam. Protons or deuterons are accelerated using magnetic-insulated ion-diode technology, and neutralized in a transient gas cell. A prototype 25-kA, 100-kV, 1-{mu}s accelerator is under construction at Los Alamos. Initial experiments will focus on ITER-related issues of beam energy distribution, current density, pulse length, divergence, propagation, impurity content, reproducibility, and maintenance.

  8. Efficient laser production of energetic neutral beams

    NASA Astrophysics Data System (ADS)

    Mollica, F.; Antonelli, L.; Flacco, A.; Braenzel, J.; Vauzour, B.; Folpini, G.; Birindelli, G.; Schnuerer, M.; Batani, D.; Malka, V.

    2016-03-01

    Laser-driven ion acceleration by intense, ultra-short, laser pulse has received increasing attention in recent years, and the availability of much compact and versatile ions sources motivates the study of laser-driven sources of energetic neutral atoms. We demonstrate the production of a neutral and directional beam of hydrogen and carbon atoms up to 200 keV per nucleon, with a peak flow of 2.7× {{10}13} atom s-1. Laser accelerated ions are neutralized in a pulsed, supersonic argon jet with tunable density between 1.5× {{10}17} cm-3and 6× {{10}18} cm-3. The neutralization efficiency has been measured by a time-of-flight detector for different argon densities. An optimum is found, for which complete neutralization occurs. The neutralization rate can be explained only at high areal densities (>1× {{10}17} cm-2) by single electron charge transfer processes. These results suggest a new perspective for the study of neutral production by laser and open discussion of neutralization at a lower density.

  9. Calorimetric detection of neutral-atom content of ion beam

    NASA Technical Reports Server (NTRS)

    Roberts, A. S., Jr.

    1974-01-01

    Energy deposition technique deduces neutral-beam flux or dose from measured values of incremental resistance increases in platinum wire passed through beam. Steady-state heat balance analysis led to equivalent neutral-beam current. Method was used to detect neutral-atom content of 60-keV argon ion beam.

  10. A Neutral Beam Injector Upgrade for NSTX

    SciTech Connect

    T. Stevenson; B McCormack; G.D. Loesser; M. Kalish; S. Ramakrishnan; L. Grisham; J. Edwards; M. Cropper; G. Rossi; A. von Halle; M. Williams

    2002-01-18

    The National Spherical Torus Experiment (NSTX) capability with a Neutral Beam Injector (NBI) capable of 80 kiloelectronvolt (keV), 5 Megawatt (MW), 5 second operation. This 5.95 million dollar upgrade reused a previous generation injector and equipment for technical, cost, and schedule reasons to obtain these specifications while retaining a legacy capability of 120 keV neutral particle beam delivery for shorter pulse lengths for possible future NSTX experiments. Concerns with NBI injection included power deposition in the plasma, aiming angles from the fixed NBI fan array, density profiles and beam shine through, orbit losses of beam particles, and protection of the vacuum vessel wall against beam impingement. The upgrade made use of the beamline and cryo panels from the Neutral Beam Test Stand facility, existing power supplies and controls, beamline components and equipment not contaminated by tritium during DT [deuterium-tritium] experiments, and a liquid Helium refrigerator plant to power and cryogenically pump a beamline and three ion sources. All of the Tokamak Fusion Test Reactor (TFTR) ion sources had been contaminated with tritium, so a refurbishment effort was undertaken on selected TFTR sources to rid the three sources destined for the NSTX NBI of as much tritium as possible. An interconnecting duct was fabricated using some spare and some new components to attach the beamline to the NSTX vacuum vessel. Internal vacuum vessel armor using carbon tiles was added to protect the stainless steel vacuum vessel from beam impingement in the absence of plasma and interlock failure. To date, the NBI has operated to 80 keV and 5 MW and has injected requested power levels into NSTX plasmas with good initial results, including high beta and strong heating characteristics at full rated plasma current.

  11. Neutralization efficiency estimation in a neutral beam source based on inductively coupled plasma

    SciTech Connect

    Vozniy, O. V.; Yeom, G. Y.

    2009-01-01

    This study examined the optimal conditions of neutral beam generation to maintain a high degree of neutralization and focusing during beam energy variation for a neutral beam source based on inductively coupled plasma with a three-grid ion beam acceleration system. The neutral beam energy distribution was estimated by measuring the energy profiles of ions that 'survived' the neutralization after reflection. The energy measurements of the primary and reflected ions showed narrow distribution functions, each with only one peak. At higher beam energies, both the ratio of the ion energy loss to the primary energy and the degree of energy divergence decreased, confirming the precise alignment of the neutral beam. The neutralization efficiency of the neutral beam source with a three-grid acceleration system was found to be affected mainly by the beam angle divergence rather than by the particle translation energy.

  12. The Neutralization of Ion-Rocket Beams

    NASA Technical Reports Server (NTRS)

    Kaufman, Harold R.

    1961-01-01

    The experimental ion-beam behavior obtained without neutralizers is compared with both simple collision theory and plasma-wave theory. This comparison indicates that plasma waves play an important part in beam behavior, although the present state of plasma-wave theory does not permit more than a qualitative comparison. The theories of immersed-emitter and electron-trap neutralizer operation are discussed; and, to the extent permitted by experimental data, the theory is compared with experimental results. Experimental data are lacking completely at the present time for operation in space. The results that might be expected in space and the means of simulating such operation in Earth-bound facilities, however, are discussed.

  13. Neutral beam source commercialization study. Final report

    SciTech Connect

    King, H.J.

    1980-06-01

    The basic tasks of this Phase II project were to: generate a set of design drawings suitable for quantity production of sources of this design; fabricate a functional neutral beam source incorporating as many of the proposed design changes as proved feasible; and document the procedures and findings developed during the contract. These tasks have been accomplished and represent a demonstrated milestone in the industrialization of this complete device.

  14. Power threshold for neutral beam current drive

    SciTech Connect

    Politzer, P.A. ); Porter, G.D. )

    1989-10-02

    For fully noninductive current drive in tokamaks using neutral beams, there is a power and density threshold condition, setting a minimum value for P{sup 3/2}/n{sup 2}. If this condition is not met, stationary state cannot occur, and a tokamak discharge will collapse. This is a consequence of the coupling between current and electron temperature, or between current drive efficiency and energy confinement time. 4 figs.

  15. Progress of beam diagnosis system for EAST neutral beam injector

    SciTech Connect

    Xu, Y. J. Hu, C. D.; Yu, L.; Liang, L. Z.; Zhang, W. T.; Chen, Y.; Li, X.

    2016-02-15

    Neutral beam injection has been recognized as one of the most effective means for plasma heating. According to the research plan of the EAST physics experiment, two sets of neutral beam injector (NBI) were built and operational in 2014. The paper presents the development of beam diagnosis system for EAST NBI and the latest experiment results obtained on the test-stand and EAST-NBI-1 and 2. The results show that the optimal divergence angle is (0.62°, 1.57°) and the full energy particle is up to 77%. They indicate that EAST NBI work properly and all targets reach or almost reach the design targets. All these lay a solid foundation for the achievement of high quality plasma heating for EAST.

  16. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

    SciTech Connect

    Umeda, N. Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M.

    2015-04-08

    R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  17. Neutral Beam Ion Loss Modeling for NSTX

    SciTech Connect

    D. Mikkelsen; D.S. Darrow; L. Grisham; R. Akers; S. Kaye

    1999-06-01

    A numerical model, EIGOL, has been developed to calculate the loss rate of neutral beam ions from NSTX and the resultant power density on the plasma facing components. This model follows the full gyro-orbit of the beam ions, which can be a significant fraction of the minor radius. It also includes the three-dimensional structure of the plasma facing components inside NSTX. Beam ion losses from two plasma conditions have been compared: {beta} = 23%, q{sub 0} = 0.8, and {beta} = 40%, q{sub 0} = 2.6. Global losses are computed to be 4% and 19%, respectively, and the power density on the rf antenna is near the maximum tolerable levels in the latter case.

  18. Concepts for the magnetic design of the MITICA neutral beam test facility ion acceleratora)

    NASA Astrophysics Data System (ADS)

    Chitarin, G.; Agostinetti, P.; Marconato, N.; Marcuzzi, D.; Sartori, E.; Serianni, G.; Sonato, P.

    2012-02-01

    The megavolt ITER injector concept advancement neutral injector test facility will be constituted by a RF-driven negative ion source and by an electrostatic Accelerator, designed to produce a negative Ion with a specific energy up to 1 MeV. The beam is then neutralized in order to obtain a focused 17 MW neutral beam. The magnetic configuration inside the accelerator is of crucial importance for the achievement of a good beam efficiency, with the early deflection of the co-extracted and stripped electrons, and also of the required beam optic quality, with the correction of undesired ion beamlet deflections. Several alternative magnetic design concepts have been considered, comparing in detail the magnetic and beam optics simulation results, evidencing the advantages and drawbacks of each solution both from the physics and engineering point of view.

  19. Concepts for the magnetic design of the MITICA neutral beam test facility ion accelerator.

    PubMed

    Chitarin, G; Agostinetti, P; Marconato, N; Marcuzzi, D; Sartori, E; Serianni, G; Sonato, P

    2012-02-01

    The megavolt ITER injector concept advancement neutral injector test facility will be constituted by a RF-driven negative ion source and by an electrostatic Accelerator, designed to produce a negative Ion with a specific energy up to 1 MeV. The beam is then neutralized in order to obtain a focused 17 MW neutral beam. The magnetic configuration inside the accelerator is of crucial importance for the achievement of a good beam efficiency, with the early deflection of the co-extracted and stripped electrons, and also of the required beam optic quality, with the correction of undesired ion beamlet deflections. Several alternative magnetic design concepts have been considered, comparing in detail the magnetic and beam optics simulation results, evidencing the advantages and drawbacks of each solution both from the physics and engineering point of view.

  20. Multicusp Trap as Model of Plasma Neutralizer for ITER Neutral Beam Injector

    SciTech Connect

    Belyaev, V.A.; Dubrovin, M.M.; Kosarev, P.M.; Skovoroda, A.A.; Spitsyn, A.V.; Terent'ev, A.A.; Yanchenkov, S.V.; Zhil'tsov, V.A.; Zubarev, V.F.

    2005-01-15

    Increasing the negative ions beam neutralization efficiency in NBI system is rather attractive. It is known, that neutralization efficiency of negative ion beam on plasma is higher than on gas. The model of plasma neutralizer for ITER NBI system - PNX-U facility is described here. Obtained experimental results give that chosen conception is promising and plasma neutralizer allows essential improvement of NBI system.

  1. Beam loss by collimation in a neutralizer duct

    SciTech Connect

    Hamilton, G.W.; Willmann, P.A.

    1980-04-03

    Beam fractions lost by collimation in a neutralizer duct are computed in x-x' phase space by using three examples of slab beam distributions under a broad range of duct dimensions, beam half-widths, and beam divergences. The results can be used to design compact neutralizers and to specify beam requirements. The computer code ILOST can be used under a broad range of beam conditions to compute the fraction lost by collimation.

  2. Electrostatic steering and beamlet aiming in large neutral beam injectors

    NASA Astrophysics Data System (ADS)

    Veltri, P.; Cavenago, M.; Chitarin, G.; Marcuzzi, D.; Sartori, E.; Serianni, G.; Sonato, P.

    2015-04-01

    Neutral beam injection is the main method for plasma heating in magnetic confinement fusion devices. In high energy injector (E>100 keV/amu), neutrals are obtained with reasonable efficiency by conversion of negative ions (H- or D-) via electron detachment reactions. In the case of ITER injectors, which shall operate at 1 MeV, a total ion current of ˜ 40 A is required to satisfy the heating power demand. Gridded electrodes are therefore used in the accelerator, so that 1280 negative ion beamlets are accelerated together. A carefully designed aiming system is required to control the beamlet trajectories, and to deliver their power on a focal point located several meters away from the beam source. In nowadays injectors, the aiming is typically obtained by aperture offset technique or by grid shaping. This paper discuss an alternative concept of beamlets aiming, based on an electrostatic "steerer" to be placed at the end of the accelerator. A feasibility study of this component is also presented, and its main advantages and drawbacks with respect to other methods are discussed.

  3. TFTR neutral-beam power system

    SciTech Connect

    Winje, R.A.

    1982-10-01

    The TFTR Neutral Beam Power System (NBPS) consists of the accelerator grid power supply and the auxiliary power supplies required to operate the TFTR 120-keV ion sources. The current configuration of the NBPS including the 11-MVA accelerator grid power supply and the Arc and Filament power supplies isolated for operation at accelerator grid voltages up to 120 kV, is described. The prototype NBPS has been assembled at the Princeton Plasma Physics Laboratory and has been operated. The results of the initial operation and the description and resolution of some of the technical problems encountered during the commissioning tests are presented.

  4. Targets for a Neutral Kaon Beam

    SciTech Connect

    Keith, Christopher

    2016-04-01

    A secondary beam of neutral Kaons is under consideration for Hall D at Jefferson Lab to perform spectroscopic studies of hyperons produced by K 0 L particles scattering from proton and deuteron targets. The proposed physics program would utilize the GlueX detector package currently installed in Hall D. This contribution looks at potential targets for use in the new facility, paying close attention to the existing infrastructure of GlueX and Hall D. Unpolarized cryotargets of liquid hydrogen and deuerium, as well as polarized solid targets of protons and deuterons are examined.

  5. Magnetically operated beam dump for dumping high power beams in a neutral beamline

    DOEpatents

    Dagenhart, W.K.

    1984-01-27

    It is an object of this invention to provide a beam dump system for a neutral beam generator which lowers the time-averaged power density of the beam dump impingement surface. Another object of this invention is to provide a beam dump system for a neutral particle beam based on reionization and subsequent magnetic beam position modulation of the beam onto a beam dump surface to lower the time-averaged power density of the beam dump ion impingement surface.

  6. Neutral Beam Power System for TPX

    SciTech Connect

    Ramakrishnan, S.; Bowen, O.N.; O`Conner, T.; Edwards, J.; Fromm, N.; Hatcher, R.; Newman, R.; Rossi, G.; Stevenson, T.; von Halle, A.

    1993-11-01

    The Tokamak Physics Experiment (TPX) will utilize to the maximum extent the existing Tokamak Fusion Test Reactor (TFTR) equipment and facilities. This is particularly true for the TFTR Neutral Beam (NB) system. Most of the NB hardware, plant facilities, auxiliary sub-systems, power systems, service infrastructure, and control systems can be used as is. The major changes in the NB hardware are driven by the new operating duty cycle. The TFTR Neutral Beam was designed for operation of the Sources for 2 seconds every 150 seconds. The TPX requires operation for 1000 seconds every 4500 seconds. During the Conceptual Design Phase of TPX every component of the TFTR NB Electrical Power System was analyzed to verify whether the equipment can meet the new operational requirements with our without modifications. The Power System converts 13.8 kV prime power to controlled pulsed power required at the NB sources. The major equipment involved are circuit breakers, auto and rectifier transformers surge suppression components, power tetrodes, HV Decks, and HVDC power transmission to sources. Thermal models were developed for the power transformers to simulate the new operational requirements. Heat runs were conducted for the power tetrodes to verify capability. Other components were analyzed to verify their thermal limitations. This paper describes the details of the evaluation and redesign of the electrical power system components to meet the TPX operational requirements.

  7. Novel neutralized-beam intense neutron source for fusion technology development

    SciTech Connect

    Osher, J.E.; Perkins, L.J.

    1983-07-08

    We describe a neutralized-beam intense neutron source (NBINS) as a relevant application of fusion technology for the type of high-current ion sources and neutral beamlines now being developed for heating and fueling of magnetic-fusion-energy confinement systems. This near-term application would support parallel development of highly reliable steady-state higher-voltage neutral D/sup 0/ and T/sup 0/ beams and provide a relatively inexpensive source of fusion neutrons for materials testing at up to reactor-like wall conditions. Beam-target examples described incude a 50-A mixed D-T total (ions plus neutrals) space-charge-neutralized beam at 120 keV incident on a liquid Li drive-in target, or a 50-A T/sup 0/ + T/sup +/ space-charge-neutralized beam incident on either a LiD or gas D/sub 2/ target with calculated 14-MeV neutron yields of 2 x 10/sup 15//s, 7 x 10/sup 15//s, or 1.6 x 10/sup 16//s, respectively. The severe local heat loading on the target surface is expected to limit the allowed beam focus and minimum target size to greater than or equal to 25 cm/sup 2/.

  8. International Thermonuclear Experimental Reactor (ITER) neutral beam design

    SciTech Connect

    Myers, T.J.; Brook, J.W.; Spampinato, P.T.; Mueller, J.P.; Luzzi, T.E.; Sedgley, D.W. . Space Systems Div.)

    1990-10-01

    This report discusses the following topics on ITER neutral beam design: ion dump; neutralizer and module gas flow analysis; vacuum system; cryogenic system; maintainability; power distribution; and system cost.

  9. Method of active charge and current neutralization of intense ion beams for ICF

    SciTech Connect

    Guiragossian, Z.G.T.; Orthel, J.L.; Lemons, D.S.; Thode, L.E.

    1981-01-01

    Methods of generating the beam neutralization electrons with required properties are given in the context of a Light Ion Fusion Experiment (LIFE) designed accelerator. Recently derived envelope equations for neutralized and ballistically focused intense ion beams are applied to the LIFE geometry in which 10 MeV He/sup +/ multiple beamlets coalesce and undergo 45:1 radial compression while beam pulses experience a 20:1 axial compression in the propagation range of 10 m. Both active and auto-neutralization methods are examined and found to produce initial electron temperatures consistent with the requirement of the envelope equation for both radial and axial adiabatic beam pulse compressions. The stability of neutralized beam propagation is also examined concerning the Pierce type electrostatic instability and for the case of LIFE beams it is found to have insignificant effect. A scaled experimental setup is presented which can serve to perform near term tests on the ballistically focused propagation of neutralized light ion beams.

  10. Drift compression of an intense neutralized ion beam

    SciTech Connect

    Roy, P.K.; Yu, S.S.; Henestroza, E.; Anders, A.; Bieniosek, F.M.; Coleman, J.; Eylon, S.; Greenway, W.G.; Leitner, M.; Logan, B.G.; Waldron, W.L.; Welch, D.R.; Thoma, C.; Sefkow, A.B.; Gilson, E.P.; Efthimion, P.C.; Davidson, R.C.

    2004-10-25

    Longitudinal compression of a tailored-velocity, intense neutralized ion beam has been demonstrated. The compression takes place in a 1-2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. this measurement has been confirmed independently with two different diagnostic systems.

  11. A preliminary model of ion beam neutralization. [in thruster plasmas

    NASA Technical Reports Server (NTRS)

    Parks, D. E.; Katz, I.

    1979-01-01

    A theoretical model of neutralized thruster ion beam plasmas has been developed. The basic premise is that the beam forms an electrostatic trap for the neutralizing electrons. A Maxwellian spectrum of electron energies is maintained by collisions between trapped electrons and by collective randomization of velocities of electrons injected from the neutralizer into the surrounding plasma. The theory contains the observed barometric law relationship between electron density and electron temperatures and ion beam spreading in good agreement with measured results.

  12. TFTR neutral-beam test facility

    SciTech Connect

    Turitzin, N.M.; Newman, R.A.

    1981-11-01

    TFTR Neutral Beam System will have thirteen discharge ion sources, each with its own power supply. Twelve of these will be utilized for supplemental heating of the TFTR tokamak plasma, while the thirteenth will be dedicated to an off-machine test chamber for source development and/or conditioning. A test installation for one source was set up using prototype equipment to discover and correct possible deficiencies, and to properly coordinate the equipment. This test facility represents the first opportunity for assembling an integrated system of hardware supplied by diverse vendors, each of whom designed and built his equipment to performance specifications. For the installation and coordination of the different portions of the total system, particular attention was given to personnel safety and safe equipment operation. This paper discusses various system components, their characteristics, interconnection and control. Results of the recently initiated test phase will be reported at a later date.

  13. Neutral beam dump with cathodic arc titanium gettering

    NASA Astrophysics Data System (ADS)

    Smirnov, A.; Krivenko, A. S.; Murakhtin, S. V.; Savkin, V. Ya.; Korepanov, S. A.; Putvinski, S.

    2011-03-01

    An incomplete neutral beam capture can degrade the plasma performance in neutral beam driven plasma machines. The beam dumps mitigating the shine-through beam recycling must entrap and retain large particle loads while maintaining the beam-exposed surfaces clean of the residual impurities. The cathodic arc gettering, which provides high evaporation rate coupled with a fast time response, is a powerful and versatile technique for depositing clean getter films in vacuum. A compact neutral beam dump utilizing the titanium arc gettering was developed for a field-reversed configuration plasma sustained by 1 MW, 20-40 keV neutral hydrogen beams. The titanium evaporator features a new improved design. The beam dump is capable of handling large pulsed gas loads, has a high sorption capacity, and is robust and reliable. With the beam particle flux density of 5 × 1017 H/(cm2s) sustained for 3-10 ms, the beam recycling coefficient, defined as twice the ratio of the hydrogen molecular flux leaving the beam dump to the incident flux of high-energy neutral atoms, is ˜0.7. The use of the beam dump allows us to significantly reduce the recycling of the shine-through neutral beam as well as to improve the vacuum conditions in the machine.

  14. Relative and absolute level populations in beam-foil-excited neutral helium

    NASA Technical Reports Server (NTRS)

    Davidson, J.

    1975-01-01

    Relative and absolute populations of 19 levels in beam-foil-excited neutral helium at 0.275 MeV have been measured. The singlet angular-momentum sequences show dependences on principal quantum number consistent with n to the -3rd power, but the triplet sequences do not. Singlet and triplet angular-momentum sequences show similar dependences on level excitation energy. Excitation functions for six representative levels were measured in the range from 0.160 to 0.500 MeV. The absolute level populations increase with energy, whereas the neutral fraction of the beam decreases with energy. Further, the P angular-momentum levels are found to be overpopulated with respect to the S and D levels. The overpopulation decreases with increasing principal quantum number.

  15. Radiation Safety System for SPIDER Neutral Beam Accelerator

    SciTech Connect

    Sandri, S.; Poggi, C.; Coniglio, A.; D'Arienzo, M.

    2011-12-13

    SPIDER (Source for Production of Ion of Deuterium Extracted from RF Plasma only) and MITICA (Megavolt ITER Injector Concept Advanced) are the ITER neutral beam injector (NBI) testing facilities of the PRIMA (Padova Research Injector Megavolt Accelerated) Center. Both injectors accelerate negative deuterium ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER with a maximum beam current of 40 A for both experiments. The SPIDER facility is classified in Italy as a particle accelerator. At present, the design of the radiation safety system for the facility has been completed and the relevant reports have been presented to the Italian regulatory authorities. Before SPIDER can operate, approval must be obtained from the Italian Regulatory Authority Board (IRAB) following a detailed licensing process. In the present work, the main project information and criteria for the SPIDER injector source are reported together with the analysis of hypothetical accidental situations and safety issues considerations. Neutron and photon nuclear analysis is presented, along with special shielding solutions designed to meet Italian regulatory dose limits. The contribution of activated corrosion products (ACP) to external exposure of workers has also been assessed. Nuclear analysis indicates that the photon contribution to worker external exposure is negligible, and the neutron dose can be considered by far the main radiation protection issue. Our results confirm that the injector has no important radiological impact on the population living around the facility.

  16. Technical Note: On Cerrobend shielding for 18-22MeV electron beams.

    PubMed

    Wojcicka, Jadwiga B; Yankelevich, Rafael; Werner, Barry Leonard; Lasher, Donette E

    2008-10-01

    The purpose of this study is to investigate (1) the depth at which the measurement of the block transmission factor should be made, and (2) the level of the transmission of 18 and 22MeV electron beams through conventional Cerrobend. We measured the block transmission in water phantom as ionization profiles across the beam and as ionization distributions along the central axis of the beam for 18 and 22MeV electron beams, for cone sizes ranging from 6×10cm2to25×25cm2. In our analysis, we separated the bremsstrahlung component produced in the Cerrobend block from the component originating in the head in the transmitted dose under the standard Cerrobend block. The block transmission for both beam energies and cone sizes was maximum on the central axis of the beam at depths between 0.4 and 0.7cm. For the 18MeV beam, the maximum transmission was 6.2% for the 6×10cm2 cone, and 7.4% for the 25×25cm2 cone. For the 22MeV beam, it was 9.5% for the 6×10cm2 cone, and 11.3% for the 25×25cm2 cone. For the 22MeV beam and 15×15cm2 cone, it takes 2.95 and 1.4cm of Cerrobend to reduce the maximum block transmission to 5% and 10%, respectively. The maximum dose under a blocked electron beam occurs on the central axis closer to the surface than it does for the open beam, and the block transmission factor should be defined at this shallower depth. To decrease the block transmission factor to the level of 5% on the central axis, electron beams with energy 18MeV and greater require additional shielding. © 2008 American Association of Physicists in Medicine.

  17. The influence of stray magnetic fields on ion beam neutralization

    NASA Technical Reports Server (NTRS)

    Feng, Y.-C.; Wilbur, P. J.

    1982-01-01

    An experimental investigation is described of a comparison between the ion beam neutralization characteristics of a local neutralizer (within approximately 5 cm of the beam edge) and those associated with a distant one (approximately 1 meter away from the thruster). The influence of magnetic fields in the vicinity of the neutralizer cathode orifice which are either parallel or normal to the neutralizer axis is assessed. The plasma property profiles which reflect the influence of the magnetic fields are measured. The results suggest that magnetic fields at the region of a neutralizer cathode orifice influence its ability to couple to the ion beam. They reveal that there is a potential jump from the neutralizer cathode orifice to the plasma which exists close to the orifice. This potential drop is found to increase as the axial component of magnetic flux density increases. A magnetic field perpendicular to the neutralizer axis induces a potential rise a few centimeters downstream from the neutralizer cathode.

  18. High intensity proton beam transportation through fringe field of 70 MeV compact cyclotron to beam line targets

    NASA Astrophysics Data System (ADS)

    Zhang, Xu; Li, Ming; Wei, Sumin; Xing, Jiansheng; Hu, Yueming; Johnson, Richard R.; Piazza, Leandro; Ryjkov, Vladimir

    2016-06-01

    From the stripping points, the high intensity proton beam of a compact cyclotron travels through the fringe field area of the machine to the combination magnet. Starting from there the beams with various energy is transferred to the switching magnet for distribution to the beam line targets. In the design of the extraction and transport system for the compact proton cyclotron facilities, such as the 70 MeV in France and the 100 MeV in China, the space charge effect as the beam crosses the fringe field has not been previously considered; neither has the impact on transverse beam envelope coupled from the longitudinal direction. Those have been concerned much more with the higher beam-power because of the beam loss problem. In this paper, based on the mapping data of 70 MeV cyclotron including the fringe field by BEST Cyclotron Inc (BEST) and combination magnet field by China Institute of Atomic Energy (CIAE), the beam extraction and transport are investigated for the 70 MeV cyclotron used on the SPES project at Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro (INFN-LNL). The study includes the space charge effect and longitudinal and transverse coupling mentioned above, as well as the matching of beam optics using the beam line for medical isotope production as an example. In addition, the designs of the ±45° switching magnets and the 60° bending magnet for the extracted beam with the energy from 35 MeV to 70 MeV have been made. Parts of the construction and field measurements of those magnets have been done as well. The current result shows that, the design considers the complexity of the compact cyclotron extraction area and fits the requirements of the extraction and transport for high intensity proton beam, especially at mA intensity levels.

  19. Intense ion beam neutralization using underdense background plasma

    SciTech Connect

    Berdanier, William; Roy, Prabir K.; Kaganovich, Igor

    2015-01-15

    Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

  20. Plasma heating with multi-MeV neutral atom beams

    SciTech Connect

    Grisham, L.R.; Post, D.E.; Mikkelsen, D.R.; Eubank, H.P.

    1981-10-01

    We explore the utility and feasibility of neutral beams of greater than or equal to 6 AMU formed from negative ions, and also of D/sup 0/ formed from D/sup -/. The negative ions would be accelerated to approx. 1 to 2 MeV/AMU and neutralized, whereupon the neutral atoms would be used to heat and, perhaps, to drive current in magnetically confined plasmas. Such beams appear feasible and offer the promise of significant advantages relative to conventional neutral beams based on positive deuterium ions at approx. 150 keV.

  1. Calculation of Neutral Beam Injection into SSPX

    SciTech Connect

    Pearlstein, L D; Casper, T A; Hill, D N; LoDestro, L L; McLean, H S

    2006-06-13

    The SSPX spheromak experiment has achieved electron temperatures of 350eV and confinement consistent with closed magnetic surfaces. In addition, there is evidence that the experiment may be up against an operational beta limit for Ohmic heating. To test this barrier, there are firm plans to add two 0.9MW Neutral Beam (NB) sources to the experiment. A question is whether the limit is due to instability. Since the deposited Ohmic power in the core is relatively small the additional power from the beams is sufficient to significantly increase the electron temperature. Here we present results of computations that will support this contention. We have developed a new NB module to calculate the orbits of the injected fast fast-ions. The previous computation made heavy use of tokamak ordering which fails for a tight-aspect-ratio device, where B{sub tor} {approx} B{sub pol}. The model calculates the deposition from the NFREYA package [1]. The neutral from the CX deposition is assumed to be ionized in place, a high-density approximation. The fast ions are then assumed to fill a constant angular momentum orbit. And finally, the fast ions immediately assume the form of a dragged down distribution. Transfer rates are then calculated from this distribution function [2]. The differential times are computed from the orbit times and the particle weights in each flux zone (the sampling bin) are proportional to the time spent in the zone. From this information the flux-surface-averaged profiles are obtained and fed into the appropriate transport equation. This procedure is clearly approximate, but accurate enough to help guide experiments. A major advantage is speed: 5000 particles can be processed in under 4s on our fastest LINUX box. This speed adds flexibility by enabling a ''large'' number of predictive studies. Similar approximations, without the accurate orbit calculation presented here, had some success comparing with experiment and TRANSP [3]. Since our procedure does not

  2. Plasma neutralizers for H negative or D negative beams

    NASA Astrophysics Data System (ADS)

    Berkner, K. H.; Pyle, R. V.; Savas, S. E.; Stalder, K. R.

    1980-10-01

    Plasma neutralizers can produce higher conversion efficiencies than are obtainable with gas neutralizers for the production of high-energy neutral beams from negative hydrogen ions. Little attention has been paid to experimental neutralizer studies because of the more critical problems connected with the development of negative-ion sources. With the prospect of accelerating ampere dc beams from extrapolatable ion sources some time next year, plasma neutralizers are being re-examined. Some basic considerations, two introductory experiments, and a next-step experiment are described.

  3. Space Charge Neutralization of DEMO Relevant Negative Ion Beams at Low Gas Density

    SciTech Connect

    Surrey, Elizabeth; Porton, Michael

    2011-09-26

    The application of neutral beams to future power plant devices (DEMO) is dependent on achieving significantly improved electrical efficiency and the most promising route to achieving this is by implementing a photoneutralizer in place of the traditional gas neutralizer. A corollary of this innovation would be a significant reduction in the background gas density through which the beam is transported between the accelerator and the neutralizer. This background gas is responsible for the space charge neutralization of the beam, enabling distances of several metres to be traversed without significant beam expansion. This work investigates the sensitivity of a D{sup -} beam to reduced levels of space charge compensation for energies from 100 keV to 1.5 MeV, representative of a scaled prototype experiment, commissioning and full energy operation. A beam transport code, following the evolution of the phase space ellipse, is employed to investigate the effect of space charge on the beam optics. This shows that the higher energy beams are insensitive to large degrees of under compensation, unlike the lower energies. The probable degree of compensation at low gas density is then investigated through a simple, two component beam-plasma model that allows the potential to be negative. The degree of under-compensation is dependent on the positive plasma ion energy, one source of which is dissociation of the gas by the beam. The subsequent space charge state of the beam is shown to depend upon the relative times for equilibration of the dissociation energy and ionization by the beam ions.

  4. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  5. Studies of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    Space-charge forces limit the possible transverse compression of high perveance ion beams that are used in ion-beam-driven high energy density physics applications; the minimum radius to which a beam can be focused is an increasing function of perveance. The limit can be overcome if a plasma is introduced in the beam path between the focusing element and the target in order to neutralize the space charge of the beam. This concept has been implemented on the Neutralized Drift Compression eXperiment (NDCX) at LBNL using Ferroelectric Plasma Sources (FEPS). In our experiment at PPPL, we propagate a perveance-dominated ion beam through a FEPS to study the effect of the neutralizing plasma on the beam envelope and its evolution in time. A 30-60 keV space-charge-dominated Argon beam is focused with an Einzel lens into a FEPS located at the beam waist. The beam is intercepted downstream from the FEPS by a movable Faraday cup that provides time-resolved 2D current density profiles of the beam spot on target. We report results on: (a) dependence of charge neutralization on FEPS plasma density; (b) effects on beam emittance, and (c) time evolution of the beam envelope after the FEPS pulse. Research supported by the U.S. Department of Energy.

  6. Experimental study of the stability of a neutralized electron beam

    SciTech Connect

    Kudelainen, V.I.; Parkhomchuk, V.V.; Pestrikov, D.V.

    1983-05-01

    Results are reported from measurements of the spectral properties of a long neutralized electron beam in the NAP-M proton storage ring. It is shown that when the number of secondary electrons is small, both the longitudinal and the transverse oscillations are strongly damped, so that beam instability is suppressed. The current density of the neutralized electron beam produced in the experiments was approx.10/sup 2/ times greater than the theoretical value determined from the instability threshold for nonaxisymmetric oscillations.

  7. mA beam acceleration efforts on 100 MeV H- cyclotron at CIAE

    NASA Astrophysics Data System (ADS)

    Zhang, Tianjue; An, Shizhong; Lv, Yinlong; Ge, Tao; Jia, Xianlu; Ji, Bin; Yin, Zhiguo; Pan, Gaofeng; Cao, Lei; Guan, Fengping; Yang, Jianjun; Li, Zhenguo; Zhao, Zhenlu; Wu, Longcheng; Zhang, He; Wang, Jingfeng; Zhang, Yiwang; Liu, Jingyuan; Li, Shiqiang; Lu, Xiaotong; Liu, Zhenwei; Li, Yaoqian; Guo, Juanjuan; Cao, Xuelong; Guan, Leilei; Wang, Fei; Wang, Yang; Yang, Guang; Zhang, Suping; Hou, Shigang; Wang, Feng

    2017-09-01

    Various technologies for high current compact H- cyclotron have been developed at CIAE since 1990s. A 375 μA proton beam was extracted from a 30 MeV compact H- cyclotron CYCIAE-30 at the end of 1994. A central region model cyclotron CYCIAE-CRM was developed for the design verification of a 100 MeV high current compact H- cyclotron CYCIAE-100. It is also a 10 MeV proton machine as a prototype for PET application. A 430 μA beam was achieved in 2009. The first beam was extracted from the CYCIAE-100 cyclotron on July 4, 2014, the operation stability has been improved and beam current has been increased gradually. A 1.1 mA proton beam was measured on the internal target in July 2016. The effort for an increasing of proton beam has continued till now. In this paper, the effort on several aspects for mA beam development will be presented, including the multi-cusp source, buncher, matching from the energy of the injected beam, vertical beam line and central region, beam loading of the RF system and instrumentation for beam diagnostics etc.

  8. The production of low-energy neutral oxygen beams by grazing-incidence neutralization

    NASA Technical Reports Server (NTRS)

    Albridge, R. G.; Haglund, R. F.; Tolk, N. H.; Daech, A. F.

    1987-01-01

    The Vanderbilt University neutral oxygen facility produces beams of low-energy neutral oxygen atoms by means of grazing-incidence collisions between ion beams and metal surfaces. Residual ions are reflected by applied electric fields. This method can utilize initial ion beams of either O(+) or O2(+) since a very large percentage of molecular oxygen ions are dissociated when they undergo grazing-incidence neutralization. The method of neutralization is applicable to low-energy beams and to all ions. Particular emphasis is on O and N2 beams for simulation of the low Earth orbit space environment. Since the beam is a pure O-neutral beam and since measurements of the interaction of the beam with solid surfaces are made spectroscopically, absolute reaction rates can be determined. The technique permits the beams to be used in conjunction with electron and photon irradiation for studies of synergistic effects. Comparisons of optical spectra of Kapton excited by 2.5-keV O, O(+), and O2(+) show significant differences. Optical spectra of Kapton excited by neutral oxygen beams of less than 1 keV have been recorded.

  9. A Faraday Cup with high frequency response for a 200 MeV LINAC proton beam

    SciTech Connect

    Zucker, M.S.; Bittner, J.W.

    1991-01-01

    The purpose of this device, composed essentially of coaxial line elements, is monitoring, on a per micropulse basis, the beam intensity of a 200 MeV LINAC at the BNL Radiation Effects Facility. The center conductor of the coaxial line acts as a beam stop. The output pulses are suitable for fast timing. 2 refs., 5 figs.

  10. Using neutral beams as a light ion beam probe (invited)

    DOE PAGES

    Chen, Xi; Heidbrink, William W.; Van Zeeland, Michael A.; ...

    2014-08-05

    By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of 1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge, and 2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fieldsmore » appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g. Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally-imposed 3D fields, e.g. magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. Additionally, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.« less

  11. Using neutral beams as a light ion beam probe (invited)

    SciTech Connect

    Chen, Xi; Heidbrink, William W.; Van Zeeland, Michael A.; Kramer, Gerrit J.; Pace, David C.; Petty, Craig C.; Austin, Max E.; Fisher, Raymond K.; Hanson, Jeremy M.; Nazikian, Raffi; Zeng, L.

    2014-08-05

    By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of 1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge, and 2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fields appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g. Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally-imposed 3D fields, e.g. magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. Additionally, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.

  12. Using neutral beams as a light ion beam probe (invited)

    SciTech Connect

    Chen, Xi; Heidbrink, W. W.; Van Zeeland, M. A.; Pace, D. C.; Petty, C. C.; Fisher, R. K.; Kramer, G. J.; Nazikian, R.; Austin, M. E.; Hanson, J. M.; Zeng, L.

    2014-11-15

    By arranging the particle first banana orbits to pass near a distant detector, the light ion beam probe (LIBP) utilizes orbital deflection to probe internal fields and field fluctuations. The LIBP technique takes advantage of (1) the in situ, known source of fast ions created by beam-injected neutral particles that naturally ionize near the plasma edge and (2) various commonly available diagnostics as its detector. These born trapped particles can traverse the plasma core on their inner banana leg before returning to the plasma edge. Orbital displacements (the forces on fast ions) caused by internal instabilities or edge perturbing fields appear as modulated signal at an edge detector. Adjustments in the q-profile and plasma shape that determine the first orbit, as well as the relative position of the source and detector, enable studies under a wide variety of plasma conditions. This diagnostic technique can be used to probe the impact on fast ions of various instabilities, e.g., Alfvén eigenmodes (AEs) and neoclassical tearing modes, and of externally imposed 3D fields, e.g., magnetic perturbations. To date, displacements by AEs and by externally applied resonant magnetic perturbation fields have been measured using a fast ion loss detector. Comparisons with simulations are shown. In addition, nonlinear interactions between fast ions and independent AE waves are revealed by this technique.

  13. Neutralization tests on the SERT II spacecraft. [of ion beams

    NASA Technical Reports Server (NTRS)

    Kerslake, W. R.; Domitz, S.

    1979-01-01

    Orbit precession returned the SERT II spacecraft to continuous sunlight in January 1979 for the first time since early 1972, and new experiments were planned and conducted. Neutralization of an ion beam was accomplished by a second neutralizer cathode located 1 meter away. Plasma potential measurements were made of the plasma surrounding the ion beam and connecting the beam to the second neutralizer. When the density of the connecting plasma was increased by turning on the main discharge of a neighboring ion thruster, the neutralization of the ion beam occurred with improved (lower) coupling voltage. These and other tests reported should aid in the future design of spacecraft using electric thruster systems. Data taken indicate that cross neutralization of ion thrusters in a multiple thruster array should occur readily.

  14. Spatial calibration of a tokamak neutral beam diagnostic using in situ neutral beam emission

    SciTech Connect

    Chrystal, Colin; Burrell, Keith H.; Grierson, Brian A.; Pace, David C.

    2015-10-20

    Neutral beam injection is used in tokamaks to heat, apply torque, drive non-inductive current, and diagnose plasmas. Neutral beam diagnostics need accurate spatial calibrations to benefit from the measurement localization provided by the neutral beam. A new technique has been developed that uses in-situ measurements of neutral beam emission to determine the spatial location of the beam and the associated diagnostic views. This technique was developed to improve the charge exchange recombination diagnostic (CER) at the DIII-D tokamak and uses measurements of the Doppler shift and Stark splitting of neutral beam emission made by that diagnostic. These measurements contain information about the geometric relation between the diagnostic views and the neutral beams when they are injecting power. This information is combined with standard spatial calibration measurements to create an integrated spatial calibration that provides a more complete description of the neutral beam-CER system. The integrated spatial calibration results are very similar to the standard calibration results and derived quantities from CER measurements are unchanged within their measurement errors. Lastly, the methods developed to perform the integrated spatial calibration could be useful for tokamaks with limited physical access.

  15. Overview of the negative ion based neutral beam injectors for ITER

    SciTech Connect

    Schunke, B. Boilson, D.; Chareyre, J.; Choi, C.-H.; Decamps, H.; El-Ouazzani, A.; Geli, F.; Graceffa, J.; Hemsworth, R.; Kushwah, M.; Roux, K.; Shah, D.; Singh, M.; Svensson, L.; Urbani, M.

    2016-02-15

    The ITER baseline foresees 2 Heating Neutral Beams (HNB’s) based on 1 MeV 40 A D{sup −} negative ion accelerators, each capable of delivering 16.7 MW of deuterium atoms to the DT plasma, with an optional 3rd HNB injector foreseen as a possible upgrade. In addition, a dedicated diagnostic neutral beam will be injecting ≈22 A of H{sup 0} at 100 keV as the probe beam for charge exchange recombination spectroscopy. The integration of the injectors into the ITER plant is nearly finished necessitating only refinements. A large number of components have passed the final design stage, manufacturing has started, and the essential test beds—for the prototype route chosen—will soon be ready to start.

  16. Beam flatness perturbation effects of a perforated thermoplastic immobilization device on 6 and 12 MeV electron beams.

    PubMed

    Van Way, R L; Williams, R O; Johnstone, P A; Papin, P J

    1996-12-01

    Perforated thermoplastic masks are widely used in radiotherapy of head and neck malignancies. They provide for patient immobilization and increase setup reproducibility. Some oncology treatment centers cut mask portals (windows) for the beam to pass through; for those centers that do not, the mask affects beam fluence. The extent to which beam flatness is altered by such a mask is investigated. The effects of perforated thermoplastic on 6 MeV and 12 MeV electron beams was described in terms of optical density differences in a comparative film study. Variations of beam flatness were documented of up to 11.8% at 5 mm depth for 6 MeV, and 8.1% for 12 MeV electrons. The depth at which this effect may be considered insignificant (mean optical density differences < 2%) is approximately 10 mm for both beam energies. For clinical situations where the target volume is superficial, some consideration should be given to beam inhomogeneity caused by the mask.

  17. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    SciTech Connect

    Kaita, R.; Heidbrink, W.W.; Hammett, G.W.; Chan, A.A.; England, A.C.; Hendel, H.W.; Medley, S.S.; Nieschmidt, E.; Roquemore, A.L.; Scott, S.D.

    1986-04-01

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and /sup 3/He ions, respectively. When the plasma was compressed, the d(d,n)/sup 3/He fusion reaction rate increased a factor of five, and the /sup 3/He(d,p)/sup 4/He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling.

  18. Neoclassical electron transport in tokamaks with neutral-beam injection

    SciTech Connect

    Helander, P.; Akers, R.J.

    2005-04-15

    The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.

  19. A 600 MeV cyclotron for radioactive beam production

    SciTech Connect

    Clark, D.J.

    1993-05-17

    The magnetic field design for a 600 MeV proton cyclotron is described. The cyclotron has a single stage, a normal conducting magnet coil and a 9.8 m outside yoke diameter. It has 8 sectors, with a transition to 4 sectors in the center region. The magnetic field design was done using 1958 Harwell rectangular ridge system measurements and was compared with recent 3-dimensional field calculations with the program TOSCA at NSCL. The center region 4--8 sector transition focussing was also checked with TOSCA.

  20. A 0. 5 to 3. 0 MeV monoenergetic positron beam

    SciTech Connect

    Huomo, H.; AsokaKumar, P.; Henderson, S.D.; Phlips, B.F.; Mayer, R.; McDonough, J.; Hacker, H.; McCorkle, S.; Schnitzenbaumer, P.; Greenberg, J.S.

    1988-01-01

    An adjustable, 0.5--3 MeV monoenergetic positron beam has been constructed at Brookhaven. Currently a /sup 22/Na source with a W(100) foil transmission moderator produces a 1.1 mm FWHN beam with an intensity of 3/times/10/sup 5/ e/sup +//sec at a target located downstream from the accelerator. The divergence of the beam is less than 0.1/degree/ at 2.2 MeV energy. A SOA gun with 2 lens transport system brings the beam to a focus at the entrance of an electrostatic 3 MeV Dynamitron accelerator. The post acceleration beam transport system comprises 3 focusing solenolds, 4 sets of steering magnets and a 90/degree/ double focusing bending magnet. The beam energy spread at the target is <1 keV FWHN deduced from the beam size. Below we describe the positron extraction optics and acceleration, the construction of the beamline and the beam diagnostic devices. The salient beam parameters are listed at the end of this paper. 2 refs., 3 figs., 1 tab.

  1. Short-pulse, compressed ion beams at the Neutralized Drift Compression Experiment

    DOE PAGES

    Seidl, P. A.; Barnard, J. J.; Davidson, R. C.; ...

    2016-05-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory, with 1-mm beam spot size within 2.5 ns full-width at half maximum. The ion kinetic energy is 1.2 MeV. To enable the short pulse duration and mm-scale focal spot radius, the beam is neutralized in a 1.5-meter-long drift compression section following the last accelerator cell. A short-focal-length solenoid focuses the beam in the presence of the volumetric plasma that is near the target. In the accelerator, the line-charge density increases due to the velocity ramp imparted onmore » the beam bunch. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including select topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Below the transition to melting, the short beam pulses offer an opportunity to study the multi-scale dynamics of radiation-induced damage in materials with pump-probe experiments, and to stabilize novel metastable phases of materials when short-pulse heating is followed by rapid quenching. First experiments used a lithium ion source; a new plasma-based helium ion source shows much greater charge delivered to the target.« less

  2. Short-pulse, compressed ion beams at the Neutralized Drift Compression Experiment

    NASA Astrophysics Data System (ADS)

    Seidl, P. A.; Barnard, J. J.; Davidson, R. C.; Friedman, A.; Gilson, E. P.; Grote, D.; Ji, Q.; Kaganovich, I. D.; Persaud, A.; Waldron, W. L.; Schenkel, T.

    2016-05-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory, with 1-mm beam spot size within 2.5 ns full-width at half maximum. The ion kinetic energy is 1.2 MeV. To enable the short pulse duration and mm-scale focal spot radius, the beam is neutralized in a 1.5-meter-long drift compression section following the last accelerator cell. A short-focal-length solenoid focuses the beam in the presence of the volumetric plasma that is near the target. In the accelerator, the line-charge density increases due to the velocity ramp imparted on the beam bunch. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including select topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Below the transition to melting, the short beam pulses offer an opportunity to study the multi-scale dynamics of radiation-induced damage in materials with pump-probe experiments, and to stabilize novel metastable phases of materials when short-pulse heating is followed by rapid quenching. First experiments used a lithium ion source; a new plasma-based helium ion source shows much greater charge delivered to the target.

  3. Short-pulse, compressed ion beams at the Neutralized Drift Compression Experiment

    SciTech Connect

    Seidl, P. A.; Barnard, J. J.; Davidson, R. C.; Friedman, A.; Gilson, E. P.; Grote, D.; Ji, Q.; Kaganovich, I. D.; Persaud, A.; Waldron, W. L.; Schenkel, T.

    2016-05-01

    We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment (NDCX-II) at Lawrence Berkeley National Laboratory, with 1-mm beam spot size within 2.5 ns full-width at half maximum. The ion kinetic energy is 1.2 MeV. To enable the short pulse duration and mm-scale focal spot radius, the beam is neutralized in a 1.5-meter-long drift compression section following the last accelerator cell. A short-focal-length solenoid focuses the beam in the presence of the volumetric plasma that is near the target. In the accelerator, the line-charge density increases due to the velocity ramp imparted on the beam bunch. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including select topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Below the transition to melting, the short beam pulses offer an opportunity to study the multi-scale dynamics of radiation-induced damage in materials with pump-probe experiments, and to stabilize novel metastable phases of materials when short-pulse heating is followed by rapid quenching. First experiments used a lithium ion source; a new plasma-based helium ion source shows much greater charge delivered to the target.

  4. Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center

    SciTech Connect

    S. Setiniyaz, T.A. Forest, K. Chouffani, Y. Kim, A. Freyberger

    2012-07-01

    A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

  5. Shielding measurements for a 230 MeV proton beam

    SciTech Connect

    Siebers, J.V.

    1990-01-01

    Energetic secondary neutrons produced as protons interact with accelerator components and patients dominate the radiation shielding environment for proton radiotherapy facilities. Due to the scarcity of data describing neutron production, attenuation, absorbed dose, and dose equivalent values, these parameters were measured for 230 MeV proton bombardment of stopping length Al, Fe, and Pb targets at emission angles of 0{degree}, 22{degree}, 45{degree}, and 90{degree} in a thick concrete shield. Low pressure tissue-equivalent proportional counters with volumes ranging from 1 cm{sup 3} to 1000 cm{sup 3} were used to obtain microdosimetric spectra from which absorbed dose and radiation quality are deduced. Does equivalent values and attenuation lengths determined at depth in the shield were found to vary sharply with angle, but were found to be independent of target material. Neutron dose and radiation length values are compared with Monte Carlo neutron transport calculations performed using the Los Alamos High Energy Transport Code (LAHET). Calculations used 230 MeV protons incident upon an Fe target in a shielding geometry similar to that used in the experiment. LAHET calculations overestimated measured attenuation values at 0{degree}, 22{degree}, and 45{degree}, yet correctly predicted the attenuation length at 90{degree}. Comparison of the mean radiation quality estimated with the Monte Carlo calculations with measurements suggest that neutron quality factors should be increased by a factor of 1.4. These results are useful for the shielding design of new facilities as well as for testing neutron production and transport calculations.

  6. Negative ions as a source of low energy neutral beams

    SciTech Connect

    Fink, J.H.

    1980-01-01

    Little consideration has been given to the impact of recent developments in negative ion source technology on the design of low energy neutral beam injectors. However, negative ion sources of improved operating efficiency, higher gas efficiency, and smaller beam divergence will lead to neutral deuterium injectors, operating at less than 100 keV, with better operating efficiencies and more compact layouts than can be obtained from positive ion systems.

  7. Modeling process of the neutral beam re-ionization loss

    NASA Astrophysics Data System (ADS)

    Liang, Li-Zhen; Hu, Chun-Dong; Xie, Yuan-Lai; Xie, Ya-Hong; Nbi-team

    2010-07-01

    The basic process of re-ionization loss was studied. In the drift duct there are three processes leading to re-ionization loss: the collision of neutral beam particles with the molecules of background gas, similar collisions with released molecules from the inner wall of the drift duct and the ferret-collisions among particles with different energy of the neutral beam. Mathematical models have been developed and taking EAST-NBI parameters as an example, the re-ionization loss was obtained within these models. The result indicated that in the early stage of the neutral beam injector operation the released gas was quite abundant. The amount of re-ionization loss owing to the released gas can be as high as 60%. In the case of a long-time operation of the neutral beam injector, the total re-ionization loss decreases from 13.7% to 5.7%. Then the reionization loss originating mainly from the collisions between particles of the neutral beam and the background molecules is dominant, covering about 92% of the total re-ionization loss. The drift duct pressure was the decisive factor for neutral beam re-ionization loss.

  8. Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

    NASA Astrophysics Data System (ADS)

    Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

    2015-05-01

    The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation.

  9. Progress on a 200kW Diagnostic Neutral Beam

    NASA Astrophysics Data System (ADS)

    Schartman, Ethan; Foley, E. L.; Levinton, F.; Kwan, J. W.; Leung, K. N.; Wu, Y.; Vainionpaa, H.

    2009-11-01

    The interaction of neutral beam atoms with a magnetized plasma provides diagnostic access to the interiors of fusion experiments. Parameters which can be measured using neutral beams include ion temperature and velocity, density fluctuations and also local magnetic field direction. Nova Photonics, Inc and Lawrence Berkeley National Laboratory are developing a diagnostic neutral beam for use in fusion experiments which lack neutral heating beams, or on which the heating beam is not suitable for diagnostics. Our apparatus is designed to produce a 1 s duration, 5 x 8 cm elliptical cross section hydrogen beam at energies up to 40 kV and up to 5 A current. Hydrogen ions are produced in a multicusp 13 kW, 13 MHz RF source. The extracted ions have current densities of 100 - 150 mA/cm^2. The proton fraction of the hydrogen ions is 85%. Beams are extracted from the source with a rectangular, multi-aperature grids. Details of the source performance will be presented as well as initial operation of the extraction optics and neutralizer region. This work is supported by the U.S. DOE under grant DE-FG02-05ER86256.

  10. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    DOE PAGES

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; ...

    2016-04-27

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15V before neutralization to 0.3 V,more » implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established similar to –5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-mu s surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of mu s after the high voltage pulse is applied. Lastly, it is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.« less

  11. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    SciTech Connect

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-27

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established similar to –5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-mu s surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of mu s after the high voltage pulse is applied. Lastly, it is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  12. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    SciTech Connect

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-15

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar{sup +} beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ∼5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  13. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    SciTech Connect

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-27

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established similar to –5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-mu s surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of mu s after the high voltage pulse is applied. Lastly, it is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  14. Dynamics of ion beam charge neutralization by ferroelectric plasma sources

    NASA Astrophysics Data System (ADS)

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.

    2016-04-01

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ˜5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

  15. Alignment of components and assembly of 3 MeV electron beam accelerator - a complete solution

    SciTech Connect

    Gupta, R.K.; Srivastava, S.P.; Yadav, S.K.; Jawale, S.B.; Bakhtsingh, R.I.; Ghodke, S.R.; Bhattacharjee, D.

    2014-07-01

    A 3 MeV, 30 kW DC Electron Beam Accelerator developed at BARC is installed at the Electron Beam Centre (EBC) Kharghar, Navi Mumbai. The entire accelerator assembly, spread over two floors, consists of Electron Gun, Accelerating Tube, Steering Magnet, Focusing Coil, Beam Tube, Beam Locating Aperture, Scan Magnet Chamber and Scan Horn. The complete electron beamline will be maintained under high vacuum of the order of 10{sup -6} mbar. The paper discusses about the present problem of alignment, measurement technique of alignment, reasons for misalignment, ways to solve the problem, detailed alignment procedure and equipment used for alignment work. (author)

  16. Fokker-Planck/Transport model for neutral beam driven tokamaks

    SciTech Connect

    Killeen, J.; Mirin, A.A.; McCoy, M.G.

    1980-01-01

    The application of nonlinear Fokker-Planck models to the study of beam-driven plasmas is briefly reviewed. This evolution of models has led to a Fokker-Planck/Transport (FPT) model for neutral-beam-driven Tokamaks, which is described in detail. The FPT code has been applied to the PLT, PDX, and TFTR Tokamaks, and some representative results are presented.

  17. Edge envelope equation for a ballistically focused neutralized ion beam

    SciTech Connect

    Lemons, D.S.; Thode, L.E.

    1980-11-01

    An envelope equation for a cold ion beam with overall charge and current neutralization provided by a coflowing electron gas obeying an adiabatic equation of state is derived. The derivation assumes the beam evolves self-similarly with the ion at the edge of a uniform density ion profile. Numerical and approximate analytical solutions are calculated.

  18. Neutral Beam Propagation Effects in the Upper Atmosphere.

    DTIC Science & Technology

    1984-10-01

    I 7 -AA74 6 NEUTRAL BEAR PROPAGAT ION EFFECTS IN THE UPPER7~ATMOSPHERE(U) B STON C LL CHESTNUT HILL MA DEPT OF~PHYSICS P CARINI ET AL 01 OCT 84...BUREAU OF STANDARDS 2963 A t %. -_- ’o N, r ,._ .~ , AD-A 174 896 AFGL-TR-85-0038 NEUTRAL BEAM PROPAGATION EFFECTS IN THE UPPER ATMOSPHERE P. Carini...ZIP Code) 10 SOURCE OF FUNDING NOS PROGRAM PROJECT TASK( WORK UNIT ELEMENT NO NO. NO. NO 1j 1 TITLE (Include secuit’iy ClawficaiJon) Neutral Beam

  19. Equipment for radionuclide production using a 160 MeV beam in the Moscow Meson Facility

    SciTech Connect

    Zhuikov, B.L.; Kokhanyuk, V.M.; Gabrielyants, Yu.G. |

    1995-07-01

    Equipment was installed on a 160 MeV proton beam in the linear accelerator at the Institute of Nuclear Research (INR), Russian Academy of Sciences (RAS) (Troitsk, Moscow district). For a beam of 100 {mu}A and greater, tens of curies of {sup 82}Sr in addition to {sup 109}Cd, {sup 22}Na, and other medical, industrial, and research radionuclides can be produced per year.

  20. MeV ion-beam analysis of optical data storage films

    NASA Technical Reports Server (NTRS)

    Leavitt, J. A.; Mcintyre, L. C., Jr.; Lin, Z.

    1993-01-01

    Our objectives are threefold: (1) to accurately characterize optical data storage films by MeV ion-beam analysis (IBA) for ODSC collaborators; (2) to develop new and/or improved analysis techniques; and (3) to expand the capabilities of the IBA facility itself. Using H-1(+), He-4(+), and N-15(++) ion beams in the 1.5 MeV to 10 MeV energy range from a 5.5 MV Van de Graaff accelerator, film thickness (in atoms/sq cm), stoichiometry, impurity concentration profiles, and crystalline structure were determined by Rutherford backscattering (RBS), high-energy backscattering, channeling, nuclear reaction analysis (NRA) and proton induced X-ray emission (PIXE). Most of these techniques are discussed in detail in the ODSC Annual Report (February 17, 1987), p. 74. The PIXE technique is briefly discussed in the ODSC Annual Report (March 15, 1991), p. 23.

  1. Nonlinear transient neutralization theory of ion beams with dissipation

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1975-01-01

    An analytical theory of nonlinear neutralization waves generated by injection of electrons from a grid in the direction of a homogeneous ion beam of uniform velocity and infinite extension is presented. The electrons are assumed to interact with the ions through the self-consistent space charge field and by strong collective interactions. The associated nonlinear boundary-value problem is solved in closed form by means of a von Mises transformation. It is shown that the electron gas moves into the ion space in the form of a discontinuous neutralization wave. This periodic wave structure is damped out by intercomponent momentum transfer, i.e., after a few relaxation lengths a quasi-neutral beam results. The relaxation scale in space agrees with neutralization experiments of rarefied ion beams, if the collective momentum transfer between the electron and ion streams is assumed to be of the Buneman type.

  2. Very-high-level neutral-beam control system

    SciTech Connect

    Elischer, V.; Jacobson, V.; Theil, E.

    1981-10-01

    As increasing numbers of neutral beams are added to fusion machines, their operation can consume a significant fraction of a facility's total resources. LBL has developed a very high level control system that allows a neutral beam injector to be treated as a black box with just 2 controls: one to set the beam power and one to set the pulse duration. This 2 knob view allows simple operation and provides a natural base for implementing even higher level controls such as automatic source conditioning.

  3. High brilliance negative ion and neutral beam source

    DOEpatents

    Compton, Robert N.

    1991-01-01

    A high brilliance mass selected (Z-selected) negative ion and neutral beam source having good energy resolution. The source is based upon laser resonance ionization of atoms or molecules in a small gaseous medium followed by charge exchange through an alkali oven. The source is capable of producing microampere beams of an extremely wide variety of negative ions, and milliampere beams when operated in the pulsed mode.

  4. Studies on Neutral Beam Injection into the SSPX Spheromak Plasma

    SciTech Connect

    Jayakumar, R; Pearlstein, L D; Casper, T A; Fowler, T K; Hill, D N; Hudson, B; McLean, H; Moller, J

    2007-10-19

    In the Sustained Spheromak Physics Experiment, (SSPX) ['Improved operation of the SSPX spheromak', R.D. Wood, D.N. Hill, E.B. Hooper, S. Woodruff1, H.S. McLean and B.W. Stallard, Nucl. Fusion 45 1582-1588 (2005)], plasmas with core electron temperatures reaching up to 500 eV at densities of 10{sup 20}/m{sup 3} have been sustained for several milliseconds, making them suitable as targets for neutral beam injection. High performance and further progress in understanding Spheromak plasma physics are expected if neutral beams are injected into the plasma. This paper presents the results of numerical 1.5 D modeling of the plasma to calculate neutral beam current drive and ion and electron heating. The results are presented for varying initial conditions of density, temperatures and profiles and beam energy, injection angle and power. Current drive efficiency (Ampere/Watt of absorbed power) of up to 0.08 can be achieved with best performance SSPX shots as target. Analyses of neutral beam heating indicate that ion temperatures of up to 1.5 keV and electron temperatures of up to 750 eV can be obtained with injection of about 1 MW of neutral beam for 5-10 ms and with diffusivities typically observed in SSPX. Injection targeting near the magnetic axis appears to be the best for heating and current drive. Effect of the current drive and evolution of SSPX equilibrium are discussed.

  5. Smith-Purcell radiation from a 50 MeV beam

    SciTech Connect

    Brownell, J.H.; Walsh, J.; Kirk, H.G.; Fernow, R.C.; Robertson, S.H.

    1996-10-01

    A 50 MeV electron beam and a 1 mm period, 5{degree} blaze, echelle grating have been used to produce radiation in the mid-infrared spectral region. The emission is highly collimated and forward-directed. The intensity level in the few ps pulse (2 nJ/sr) indicates a degree of coherent enhancement.

  6. The evaluation of 6 and 18 MeV electron beams for small animal irradiation

    NASA Astrophysics Data System (ADS)

    Chao, T. C.; Chen, A. M.; Tu, S. J.; Tung, C. J.; Hong, J. H.; Lee, C. C.

    2009-10-01

    A small animal irradiator is critical for providing optimal radiation dose distributions for pre-clinical animal studies. This paper focuses on the evaluation of using 6 or 18 MeV electron beams as small animal irradiators. Compared with all other prototypes which use photons to irradiate small animals, an electron irradiator has many advantages in its shallow dose distribution. Two major approaches including simulation and measurement were used to evaluate the feasibility of applying electron beams in animal irradiation. These simulations and measurements were taken in three different fields (a 6 cm × 6 cm square field, and 4 mm and 30 mm diameter circular fields) and with two different energies (6 MeV and 18 MeV). A PTW Semiflex chamber in a PTW-MP3 water tank, a PTW Markus chamber type 23343, a PTW diamond detector type 60003 and KODAK XV films were used to measure PDDs, lateral beam profiles and output factors for either optimizing parameters of Monte Carlo simulation or to verify Monte Carlo simulation in small fields. Results show good agreement for comparisons of percentage depth doses (<=2.5% for 6 MeV e; <=1.8% for 18 MeV e) and profiles (FWHM <= 0.5 mm) between simulations and measurements on the 6 cm field. Greater deviation can be observed in the 4 mm field, which is mainly caused by the partial volume effects of the detectors. The FWHM of the profiles for the 18 MeV electron beam is 32.6 mm in the 30 mm field, and 4.7 mm in the 4 mm field at d90. It will take 1-13 min to complete one irradiation of 5-10 Gy. In addition, two different digital phantoms were also constructed, including a homogeneous cylindrical water phantom and a CT-based heterogeneous mouse phantom, and were implemented into Monte Carlo to simulate dose distribution with different electron irradiations.

  7. Energy monitoring device for 1.5-2.4 MeV electron beams

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Lavalle, M.; Martelli, A.; Kovács, A.; Mehta, K.; Kuntz, F.; Plumeri, S.

    2010-03-01

    An easy-to-use and robust energy monitoring device has been developed for reliable detection of day-to-day small variations in the electron beam energy, a critical parameter for quality control and quality assurance in industrial radiation processing. It has potential for using on-line, thus providing real-time information. Its working principle is based on the measurement of currents, or charges, collected by two aluminium absorbers of specific thicknesses (dependent on the beam energy), insulated from each other and positioned within a faraday cup-style aluminium cage connected to the ground. The device has been extensively tested in the energy range of 4-12 MeV under standard laboratory conditions at Institute of Isotopes and CNR-ISOF using different types of electron accelerators; namely, a TESLA LPR-4 LINAC (3-6 MeV) and a L-band Vickers LINAC (7-12 MeV), respectively. This device has been also tested in high power electron beam radiation processing facilities, one equipped with a 7-MeV LUE-8 linear accelerator used for crosslinking of cables and medical device sterilization, and the other equipped with a 10 MeV Rhodotron TT100 recirculating accelerator used for in-house sterilization of medical devices. In the present work, we have extended the application of this method to still lower energy region, i.e. from 1.5 to 2.4 MeV. Also, we show that such a device is capable of detecting deviation in the beam energy as small as 40 keV.

  8. ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

    2012-03-01

    ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from

  9. Facility for intense diagnostic neutral beam (IDNB) development

    SciTech Connect

    Kasik, R.J.; Hinckley, W.B.; Bartsch, R.R.; Rej, D.J.; Henins, I.; Greenly, J.B.

    1993-08-01

    An intense, pulsed neutral beam source is under development for use as a probe beam on hot, burning plasmas such as in the international thermonuclear experimental reactor (ITER) which is presently in the planning stage. A pulsed, neutral hydrogen beam of 10s of kilo amperes of current can have an alpha particle, charge-exchange-recombination-spectroscopy (alpha-CHERS) signal-to-noise ratio of {approximately} 10. This beam would allow the measurement, on a single pulse of a few hundred nanoseconds duration, of the local alpha particle distribution function as well as other features of the tokamak plasma such as current density profile, impurity density, and microturbulence spectrum. The cross-sections for the CHERS diagnostic dictate operation with proton energies greater than {approximately}50keV. A pulsed neutral hydrogen source of this voltage and intensity can be achieved by neutralizing the ion flux from a magnetized ion-diode. The cross-sections for attachment and stripping, when coupled with scaling from Child-Langmiur, space-charge-limited, ion-current flow imply operation below - 100keV for maximum neutral fluence. The development of a flashover-anode, ion source for forthcoming evaluation of a neutralizing section is described below. This source operates in the accelerator voltage range 70 to 100keV. Eventually, the flashover-anode, magnetized ion-diode will be replaced with a plasma-anode, magnetized ion-diode.

  10. Dynamics of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    NASA Astrophysics Data System (ADS)

    Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C.; Ji, Qing; Persaud, Arun; Seidl, Peter A.; Schenkel, Thomas

    2016-10-01

    Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams. Here we present experimental results on charge neutralization of a high-perveance 38 keV Ar+ beam by a FEPS plasma. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Near-complete charge neutralization is established 5 μs after the driving pulse is applied to the FEPS, and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub- μs surface discharge. Measurements of current flow in the driving circuit of the FEPS suggest that plasma can be generated for tens of μs after the high voltage pulse is applied. This is confirmed by fast photography of the plasma in the 1-meter long FEPS on NDCX-II, where effective charge neutralization of the beam was achieved with the optimized FEPS timing. This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0209CH11466 (PPPL) and DE-AC0205CH11231 (LBNL).

  11. TFTR neutral beam control and monitoring for DT operations

    SciTech Connect

    O`Connor, T.; Kamperschroer, J.; Chu, J.

    1995-12-31

    Record fusion power output has recently been obtained in TFTR with the injection of deuterium and tritium neutral beams. This significant achievement was due in part to the controls, software, and data processing capabilities added to the neutral beam system for DT operations. Chief among these improvements was the addition of SUN workstations and large dynamic data storage to the existing Central Instrumentation Control and Data Acquisition (CICADA) system. Essentially instantaneous look back over the recent shot history has been provided for most beam waveforms and analysis results. Gas regulation controls allowing remote switchover between deuterium and tritium were also added. With these tools, comparison of the waveforms and data of deuterium and tritium for four test conditioning pulses quickly produced reliable tritium setpoints. Thereafter, all beam conditioning was performed with deuterium, thus saving the tritium supply for the important DT injection shots. The lookback capability also led to modifications of the gas system to improve reliability and to control ceramic valve leakage by backbiasing. Other features added to improve the reliability and availability of DT neutral beam operations included master beamline controls and displays, a beamline thermocouple interlock system, a peak thermocouple display, automatic gas inventory and cryo panel gas loading monitoring, beam notching controls, a display of beam/plasma interlocks, and a feedback system to control beam power based on plasma conditions.

  12. Thermographic calorimetry of the neutral beam injectors heating beams at TJ-II

    SciTech Connect

    Fuentes, C.; Liniers, M.; Guasp, J.; Doncel, J.; Botija, J.; Wolfers, G.; Alonso, J.; Acedo, M.; Sanchez, E.; Marcon, G.; Weber, M.; Carrasco, R.; Sarasola, X.; Zurro, B.; Tera, J.

    2006-10-15

    A new beam diagnostic based on infrared thermography has been developed for the neutral beam injectors of the stellarator TJ-II. A highly anisotropic movable target intercepts the beam at its entrance into the stellarator. The thermal print of the beam is captured with a high resolution infrared camera. The infrared images of the target can be translated, with the appropriate analysis, into power density patterns of the beam. The system is calibrated in situ with two thermocouples adiabatically mounted in the target. The two-dimensional beam power density distribution can be accurately characterized allowing beam optimization with respect to the different parameters involved in the beam formation and transport.

  13. Temporal behavior of neutral particle fluxes in TFTR (Tokamak Fusion Test Reactor) neutral beam injectors

    SciTech Connect

    Kamperschroer, J.H.; Gammel, G.M.; Roquemore, A.L.; Grisham, L.R.; Kugel, H.W.; Medley, S.S.; O'Connor, T.E.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1989-09-01

    Data from an E {parallel} B charge exchange neutral analyzer (CENA), which views down the axis of a neutral beamline through an aperture in the target chamber calorimeter of the TFTR neutral beam test facility, exhibit two curious effects. First, there is a turn-on transient lasting tens of milliseconds having a magnitude up to three times that of the steady-state level. Second, there is a 720 Hz, up to 20% peak-to-peak fluctuation persisting the entire pulse duration. The turn-on transient occurs as the neutralizer/ion source system reaches a new pressure equilibrium following the effective ion source gas throughput reduction by particle removal as ion beam. Widths of the transient are a function of the gas throughput into the ion source, decreasing as the gas supply rate is reduced. Heating of the neutalizer gas by the beam is assumed responsible, with gas temperature increasing as gas supply rate is decreased. At low gas supply rates, the transient is primarliy due to dynamic changes in the neutralizer line density and/or beam species composition. Light emission from the drift duct corroborate the CENA data. At high gas supply rates, dynamic changes in component divergence and/or spatial profiles of the source plasma are necessary to explain the observations. The 720 Hz fluctuation is attributed to a 3% peak-to-peak ripple of 720 Hz on the arc power supply amplified by the quadratic relationship between beam divergence and beam current. Tight collimation by CENA apertures cause it to accept a very small part of the ion source's velocity space, producing a signal linearly proportional to beam divergence. Estimated fluctuations in the peak power density delivered to the plasma under these conditions are a modest 3--8% peak to peak. The efffects of both phenomena on the injected neutral beam can be ameliorated by careful operion of the ion sources. 21 refs., 11 figs., 2 tabs.

  14. Absolute polarimeter for the proton-beam energy of 200 MeV

    SciTech Connect

    Zelenski, A. N.; Atoian, G.; Bogdanov, A. A.; Nurushev, S. B.; Pylaev, F. S.; Raparia, D.; Runtso, M. F.; Stephenson, E.

    2013-12-15

    A polarimeter is upgraded and tested in a 200-MeV polarized-proton beam at the accelerator-collider facility of the Brookhaven National Laboratory. The polarimeter is based on the elastic polarizedproton scattering on a carbon target at an angle of 16.2°, in which case the analyzing power is close to unity and was measured to a very high degree of precision. It is shown that, in the energy range of 190–205 MeV, the absolute polarization can be measured to a precision better than ±0.5%.

  15. Chemical modifications at Teflon interfaces induced by MeV ion beams

    NASA Astrophysics Data System (ADS)

    Ingemarsson, P. Anders; Keane, Michael P.; Gelius, Ulrik

    1989-10-01

    The effect of MeV ion beams incident on Teflon surfaces was studied by x-ray photoelectron spectroscopy (XPS). Irradiation with 20-MeV 35Cl4+ was carried out at doses ranging from 1012 to 1014 ions/cm2. Residual gas analysis was performed during irradiation to identify molecular fragments released from the Teflon surface. XPS spectra were recorded before and after ion irradiation. On some substrates, gold thin films were evaporated before and after ion bombardment, respectively, to detect possible modifications in thin-film adhesion. Changes in the XPS spectra were interpreted in terms of chemical and structural shifts, and related to the observed adhesion modifications.

  16. An overview of beam diagnostic and control systems for 50 MeV AREAL Linac

    NASA Astrophysics Data System (ADS)

    Sargsyan, A. A.; Amatuni, G. A.; Sahakyan, V. V.; Zanyan, G. S.; Martirosyan, N. W.; Vardanyan, V. V.; Grigoryan, B. A.

    2017-03-01

    Advanced Research Electron Accelerator Laboratory (AREAL) is an electron linear accelerator project with a laser driven RF gun being constructed at CANDLE Synchrotron Research Institute. After the successful operation of the gun section at 5 MeV, a program of facility energy enhancement up to 50 MeV is launched. In this paper the current status of existing diagnostic and control systems, as well as the results of electron beam parameter measurements are presented. The approaches of intended diagnostic and control systems for the upgrade program are also described.

  17. Negative ion source development for a photoneutralization based neutral beam system for future fusion reactors

    NASA Astrophysics Data System (ADS)

    Simonin, A.; Agnello, R.; Bechu, S.; Bernard, J. M.; Blondel, C.; Boeuf, J. P.; Bresteau, D.; Cartry, G.; Chaibi, W.; Drag, C.; Duval, B. P.; de Esch, H. P. L.; Fubiani, G.; Furno, I.; Grand, C.; Guittienne, Ph; Howling, A.; Jacquier, R.; Marini, C.; Morgal, I.

    2016-12-01

    In parallel to the developments dedicated to the ITER neutral beam (NB) system, CEA-IRFM with laboratories in France and Switzerland are studying the feasibility of a new generation of NB system able to provide heating and current drive for the future DEMOnstration fusion reactor. For the steady-state scenario, the NB system will have to provide a high NB power level with a high wall-plug efficiency (η ˜ 60%). Neutralization of the energetic negative ions by photodetachment (so called photoneutralization), if feasible, appears to be the ideal solution to meet these performances, in the sense that it could offer a high beam neutralization rate (>80%) and a wall-plug efficiency higher than 60%. The main challenge of this new injector concept is the achievement of a very high power photon flux which could be provided by 3 MW Fabry-Perot optical cavities implanted along the 1 MeV D- beam in the neutralizer stage. The beamline topology is tall and narrow to provide laminar ion beam sheets, which will be entirely illuminated by the intra-cavity photon beams propagating along the vertical axis. The paper describes the present R&D (experiments and modelling) addressing the development of a new ion source concept (Cybele source) which is based on a magnetized plasma column. Parametric studies of the source are performed using Langmuir probes in order to characterize and compare the plasma parameters in the source column with different plasma generators, such as filamented cathodes, radio-frequency driver and a helicon antenna specifically developed at SPC-EPFL satisfying the requirements for the Cybele (axial magnetic field of 10 mT, source operating pressure: 0.3 Pa in hydrogen or deuterium). The paper compares the performances of the three plasma generators. It is shown that the helicon plasma generator is a very promising candidate to provide an intense and uniform negative ion beam sheet.

  18. Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

    2016-04-01

    A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

  19. Performance of the PDX neutral beam wall armor

    SciTech Connect

    Kugel, H.W.; Eubank, H.P.; Kozub, T.A.; Williams, M.D.

    1985-02-01

    The PDX wall armor was designed to function as an inner wall thermal armor, a neutral beam diagnostic, and a large area inner toroidal plasma limiter. In this paper we discuss its thermal performance as wall armor during two years of PDX neutral beam heating experiments. During this period it provided sufficient inner wall protection to permit perpendicular heating injections into normal and disruptive plasmas as well as injections in the absence of plasma involving special experiments, calibrations, and tests important for the optimization and development of the PDX neutral beam injection system. Many of the design constraints and performance issues encountered in this work are relevant to the design of larger fusion devices.

  20. Optics of ion beams for the neutral beam injection system on HL-2A Tokamak

    SciTech Connect

    Zou, G. Q.; Lei, G. J.; Cao, J. Y.; Duan, X. R.

    2012-07-15

    The ion beam optics for the neutral beam injection system on HL-2A Tokomak is studied by two- dimensional numerical simulation program firstly, where the emitting surface is taken at 100 Debye lengths from the plasma electrode. The mathematical formulation, computation techniques are described. Typical ion orbits, equipotential contours, and emittance diagram are shown. For a fixed geometry electrode, the effect of plasma density, plasma potential and plasma electron temperature on ion beam optics is examined, and the calculation reliability is confirmed by experimental results. In order to improve ion beam optics, the application of a small pre-acceleration voltage ({approx}100 V) between the plasma electrode and the arc discharge anode is reasonable, and a lower plasma electron temperature is desired. The results allow optimization of the ion beam optics in the neutral beam injection system on HL-2A Tokomak and provide guidelines for designing future neutral beam injection system on HL-2M Tokomak.

  1. Performance of 200 kW Diagnostic Neutral Beam

    NASA Astrophysics Data System (ADS)

    Schartman, E.; Foley, E. L.; Levinton, F.; Kwan, J.; Leung, K. N.; Wells, R.; Wu, Y.; Vainionpaa, H.

    2010-11-01

    The interaction of neutral beam atoms with a magnetized plasma provides diagnostic access to the interiors of fusion experiments. Measurable parameters include ion temperature and velocity, density fluctuations and also local magnetic field direction. Nova Photonics, Inc and Lawrence Berkeley National Laboratory are developing a diagnostic neutral beam for use in fusion experiments which lack neutral heating beams, or on which a heating beam is not suitable for diagnostics. Our beam was designed to produce a 1 s duration, 5 x 8 cm elliptical cross section hydrogen beam at energies up to 40 kV and up to 5 A current. Details of the beam performance at 40 kV operation will be presented. The accelerator grids will be re-gapped to operate at 15-20 kV for deployment on the Lithium Tokamak Experiment. Simulations of the re-gapped grids and initial performance will be presented. This work is supported by the U.S. DOE under grant DE-FG02-05ER86256.

  2. MHD Induced Neutral Beam Ion Loss from NSTX Plasmas

    SciTech Connect

    D.S. Darrow, E.D. Fredrickson, N.N. Gorelenkov, A.L. Roquemore, and K. Shinohara

    2007-12-13

    Bursts of ~60 kHz activity on Mirnov coils occur frequently in NSTX plasmas and these are accompanied by bursts of neutral beam ion loss over a range in pitch angles. These losses have been measured with a scintillator type loss probe imaged with a high speed (>10,000 frames/s) video camera, giving the evolution of the energy and pitch angle distributions of the lost neutral beam ions over the course of the events. The instability occurs below the TAE frequency in NSTX (~100 kHz) in high beta plasmas and may be a beta driven Alfvén acoustic (BAAE) mode.

  3. Neutral Beam Injection for Plasma and Magnetic FieldDiagnostics

    SciTech Connect

    Vainionpaa, Jaakko Hannes; Leung, Ka Ngo; Kwan, Joe W.; Levinton,Fred

    2007-08-01

    At the Lawrence Berkeley National Laboratory (LBNL) adiagnostic neutral beam injection system for measuring plasma parameters,flow velocity, and local magnetic field is being developed. High protonfraction and small divergence is essential for diagnostic neutral beams.In our design, a neutral hydrogen beam with an 8 cm x 11 cm (or smaller)elliptical beam spot at 2.5 m from the end of the extraction column isproduced. The beam will deliver up to 5 A of hydrogen beam to the targetwith a pulse width of ~;1 s, once every 1 - 2 min. The H1+ ion species ofthe hydrogen beamwill be over 90 percent. For this application, we havecompared two types of RF driven multicusp ion sources operating at 13.56MHz. The first one is an ion source with an external spiral antennabehind a dielectric RF-window. The second one uses an internal antenna insimilar ion source geometry. The source needs to generate uniform plasmaover a large (8 cm x 5 cm) extraction area. We expect that the ion sourcewith internal antenna will be more efficient at producing the desiredplasma density but might have the issue of limited antenna lifetime,depending on the duty factor. For both approaches there is a need forextra shielding to protect the dielectric materials from the backstreaming electrons. The source walls will be made of insulator materialsuch as quartz that has been observed to generate plasma with higheratomic fraction than sources with metal walls. The ion beam will beextracted and accelerated by a set of grids with slits, thus forming anarray of 6 sheet-shaped beamlets. The multiple grid extraction will beoptimized using computer simulation programs. Neutralization of the beamwill be done in neutralization chamber, which has over 70 percentneutralization efficiency.

  4. Engineering polypyrrole nanotubes by 100 MeV Si9+ ion beam irradiation: enhancement of antioxidant activity.

    PubMed

    Upadhyay, J; Kumar, A

    2013-12-01

    In this work, the effect of 100 MeV Si(9+) ion beam with four different fluences on antioxidant and structural properties of polypyrrole nanotubes has been investigated. Polypyrrole nanotubes have been synthesized by reactive self degrade template method. Fragmentation of the polypyrrole nanotubes at higher fluence is revealed from the high resolution transmission electron micrograph (HRTEM) and X-ray diffraction (XRD) results. The decrease in characteristics band of polypyrrole in Fourier transmission of infrared spectra (FTIR) spectra suggests the main chain scission of polypyrrole during irradiation. The free radical scavenging activity of pristine and irradiated samples are evaluated by using α, α-diphenyl-β-picrylhydrazyl (DPPH) assay. The decline of the UV-visible absorbance at 516 nm suggests the neutralization of DPPH free radicals through the reaction with polypyrrole. Significant increase in antioxidant activity of polypyrrole nanotubes is observed with increase in ion fluence. © 2013.

  5. ECR plasma source for heavy ion beam charge neutralization

    SciTech Connect

    Efthimion, P.C.; Gilson, E.; Grisham, L.; Kolchin, P.; Davidson, E.C.; Yu, S.S.; Logan, B.G.

    2002-05-01

    Highly ionized plasmas are being considered as a medium for charge neutralizing heavy ion beams in order to focus beyond the space-charge limit. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length {approx} 0.1-2 m would be suitable for achieving a high level of charge neutralization. An ECR source has been built at the Princeton Plasma Physics Laboratory (PPPL) to support a joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The ECR source operates at 13.6 MHz and with solenoid magnetic fields of 1-10 gauss. The goal is to operate the source at pressures {approx} 10{sup -6} Torr at full ionization. The initial operation of the source has been at pressures of 10{sup -4}-10{sup -1} Torr. Electron densities in the range of 10{sup 8}-10{sup 11} cm{sup -3} have been achieved. Low-pressure operation is important to reduce ion beam ionization. A cusp magnetic field has been installed to improve radial confinement and reduce the field strength on the beam axis. In addition, axial confinement is believed to be important to achieve lower-pressure operation. To further improve breakdown at low pressure, a weak electron source will be placed near the end of the ECR source.

  6. Pierce instability in neutralized inertial confinement fusion ion beams

    SciTech Connect

    Lemons, D.S.; Cary, J.R.

    1982-06-01

    The stability of a charge and current neutralized electron-ion beam propagating between two planar boundaries is investigated. For equipotential boundaries the beam is, as originally shown by Pierce, electrostatically unstable for electron current densities above a certain limiting value. If, however, the electric field at the upstream boundary is required to vanish, there is no instability. An intermediate case, in which the two boundaries are electrically connected with a finite conductivity plasma, corresponds to the proposed use of neutralized light and heavy ion beams for inertial confinement fusion drivers. Results indicate such beams can propagate either stably or with zero-frequency Pierce instability growth rates which are probably insignificant. lectric currents; boundary conditions; current density; electric fields; plasma;

  7. Dosimetric shield evaluation with tungsten sheet in 4, 6, and 9MeV electron beams.

    PubMed

    Fujimoto, Takahiro; Monzen, Hajime; Nakata, Manabu; Okada, Takashi; Yano, Shinsuke; Takakura, Toru; Kuwahara, Junichi; Sasaki, Makoto; Higashimura, Kyoji; Hiraoka, Masahiro

    2014-11-01

    In electron radiotherapy, shielding material is required to attenuate beam and scatter. A newly introduced shielding material, tungsten functional paper (TFP), has been anticipated to become a very useful device that is lead-free, light, flexible, and easily processed, containing very fine tungsten powder at as much as 80% by weight. The purpose of this study was to investigate the dosimetric changes due to TFP shielding for electron beams. TFP (thickness 0-15mm) was placed on water or a water-equivalent phantom. Percentage depth ionization and transmission were measured for 4, 6, and 9MeV electron beams. Off-center ratio was also measured using film dosimetry at depth of dose maximum under similar conditions. Then, beam profiles and transmission with two shielding materials, TFP and lead, were evaluated. Reductions of 95% by using TFP at 0.5cm depth occurred at 4, 9, and 15mm with 4, 6, and 9MeV electron beams, respectively. It is found that the dose tend to increase at the field edge shaped with TFP, which might be influenced by the thickness. TFP has several unique features and is very promising as a useful tool for radiation protection for electron beams, among others.

  8. Output beam energy measurement of a 100-MeV KOMAC drift tube linac by using a stripline beam position monitor

    NASA Astrophysics Data System (ADS)

    Kim, Han-Sung

    2015-10-01

    The 100-MeV proton linac at the KOMAC (Korea Multi-purpose Accelerator Complex) is composed of a 50-keV proton injector, a 3-MeV RFQ (radio-frequency quadrupole) and a 100-MeV DTL (drift tube linac). The proton beam is accelerated from 3 MeV to 100 MeV through 11 DTL tanks. The precise measurement of the proton-beam's energy at the output of each DTL tank is important for the longitudinal beam dynamics and can be performed by using a time-of-flight method with a BPM (beam position monitor), which is installed between each DTL tank. The details of the output beam energy measurement of the KOMAC DTL with stripline-type BPM and BPM signal processing, along with a comparison with the simulation results, will be presented in this paper.

  9. Optimisation of 12 MeV electron beam simulation using variance reduction technique

    NASA Astrophysics Data System (ADS)

    Jayamani, J.; Termizi, N. A. S. Mohd; Kamarulzaman, F. N. Mohd; Aziz, M. Z. Abdul

    2017-05-01

    Monte Carlo (MC) simulation for electron beam radiotherapy consumes a long computation time. An algorithm called variance reduction technique (VRT) in MC was implemented to speed up this duration. This work focused on optimisation of VRT parameter which refers to electron range rejection and particle history. EGSnrc MC source code was used to simulate (BEAMnrc code) and validate (DOSXYZnrc code) the Siemens Primus linear accelerator model with the non-VRT parameter. The validated MC model simulation was repeated by applying VRT parameter (electron range rejection) that controlled by global electron cut-off energy 1,2 and 5 MeV using 20 × 107 particle history. 5 MeV range rejection generated the fastest MC simulation with 50% reduction in computation time compared to non-VRT simulation. Thus, 5 MeV electron range rejection utilized in particle history analysis ranged from 7.5 × 107 to 20 × 107. In this study, 5 MeV electron cut-off with 10 × 107 particle history, the simulation was four times faster than non-VRT calculation with 1% deviation. Proper understanding and use of VRT can significantly reduce MC electron beam calculation duration at the same time preserving its accuracy.

  10. Recent Progress of Neutral Beam Injector and Beam Emission Diagnosis in LHD

    NASA Astrophysics Data System (ADS)

    Katsunori, Ikeda; Kenichi, Nagaoka; Yasuhiko, Takeiri; Masaki, Osakabe; Katsuyoshi, Tsumori; Osamu, Kaneko

    2009-08-01

    Large size hydrogen neutral beam injectors (NBI) used a negative ion source (NNBI) as well as a proton source (PNBI) were developed for the large helical device (LHD). The injected power from NNBI and PNBI have reached 16 MW and 6.8 MW, respectively. These injected powers have outstripped the nominal beam powers. A diagnostic system of beam-emitted hydrogen visible spectrum has been installed along the beam injection axis to estimate the energy fraction on PNBI. The full energy beam component is about half which is equivalent to 70% of injected beam power. The attenuation of high energy neutral beam is also observed on NNBI. The peak density distribution is effective to increase beam deposition power.

  11. Experimental study of ion-beam self-pinched transport for MeV protons

    SciTech Connect

    Neri, J.M.; Young, F.C.; Stephanakis, S.J.; Ottinger, P.F.; Rose, D.V.; Hinshelwood, D.D.; Weber, B.V.

    1999-07-01

    A 100-kA, 1.2-MeV proton beam from a pinch-reflex ion diode on the Gamble II accelerator is used to test the concept of self-pinched ion transport. Self-pinched transport (SPT) uses the self-generated magnetic field from the ion beam to radially confine the ion beam. A proton beam is injected through a 3-cm radius aperture covered with a 2-{micro}m thick polycarbonate foil into a 10-cm radius transport region. The transport region is filled with helium at pressures of 30--250 mTorr, vacuum (10{sup {minus}4} Torr), or 1-Torr air. The beam is diagnosed with witness plates, multiple-pinhole-camera imaging onto radiochromic film, time- and space-resolved proton-scattering, and with prompt-{gamma} and nuclear-activation from LiF targets. Witness-plates and the multiple-pinhole-camera are used to determine the size, location, and uniformity of the beam at different distances from the injection aperture. A beam global divergence of 200 mrad is measured at 15 cm. At 50 cm, the beam fills the transport region. At 110 cm and 100- to 200-mTorr helium, there is evidence of beam filamentation. The measured increase in protons is consistent with the physical picture for SPT, and comparisons with IPROP simulations are in qualitative agreement with the measurements.

  12. Diagnostics of the ITER neutral beam test facility

    SciTech Connect

    Pasqualotto, R.; Serianni, G.; Agostini, M.; Brombin, M.; Dalla Palma, M.; Gazza, E.; Pomaro, N.; Rizzolo, A.; Spolaore, M.; Zaniol, B.; Sonato, P.; De Muri, M.; Croci, G.; Gorini, G.

    2012-02-15

    The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H{sup -}/D{sup -} production is enhanced by cesium evaporation, will be monitored with thermocouples, electrostatic probes, optical emission spectroscopy, cavity ring down, and laser absorption spectroscopy. The beam is analyzed by cooling water calorimetry, a short pulse instrumented calorimeter, beam emission spectroscopy, visible tomography, and neutron imaging. Design of the diagnostic systems is presented.

  13. National negative-ion-based neutral-beam development plan

    SciTech Connect

    Cooper, W.S.; Pyle, R.V.

    1983-08-01

    The plan covers facilities required, program milestones, and decision points. It includes identification of applications, experiments, theoretical research areas, development of specific technologies and reactor development and demonstration facilities required to bring about the successful application of negative-ion-based neutral beams. Particular emphasis is placed on those activities leading to use on existing plasma confinement experiments or their upgrades.

  14. Module for dielectric surfaces modification by fast neutral particles beams

    NASA Astrophysics Data System (ADS)

    Barchenko, V. T.; Lisenkov, A. A.; Babinov, N. A.

    2014-11-01

    In this paper, we describe the module for dielectric and wide-gap semiconductor surfaces modification by fast neutral beam. The module can be used for cleaning, etching or assisting of films deposition. The surface proceeding by neutral beam can prevent an accumulation of surface charge without using current compensation by inserting electrons to the beam or RF power supply. The module beside cathode and anode contains an electrode with floating potential. Insertion of the additional electrode causes electron retention in an electrostatic trap resulting the reducing of the module operating pressure. Moreover, the electrode with floating potential allows increasing the current efficient of the module. An important feature of the module is that neutralization of the ions extracted from the plasma occurs in the cathode potential well. Thereby ions that have not neutralized cannot leave nearcathode region and there are no fast ions in the output beam. Module does not contain sources of the magnetic fields or elements heated by external sources. Module operates with free cooling. Thus, the module does not need water cooling and can be freely moved in the vacuum chamber.

  15. Depth dose characteristics of elongated fields for electron beams from a 20-MeV accelerator

    SciTech Connect

    Sharma, S.C.; Wilson, D.L.

    1985-07-01

    In a Therac-20 linear accelerator, 6--20 MeV electron beams are normally produced by shaping a scanned electron beam through primary x-ray collimators and secondary electron trimmers. The collimator settings range continuously from 2 to 30 cm. Depth dose and field flatness parameters were measured for small elongated fields of the various electron energies. Depth dose of narrow fields defined either by the machine's collimator or lead cutouts agreed with data predicted from small square fields using the ''square-root'' method.

  16. Depth dose characteristics of elongated fields for electron beams from a 20-MeV accelerator.

    PubMed

    Sharma, S C; Wilson, D L

    1985-01-01

    In a Therac-20 linear accelerator, 6-20 MeV electron beams are normally produced by shaping a scanned electron beam through primary x-ray collimators and secondary electron trimmers. The collimator settings range continuously from 2 to 30 cm. Depth dose and field flatness parameters were measured for small elongated fields of the various electron energies. Depth dose of narrow fields defined either by the machine's collimator or lead cutouts agreed with data predicted from small square fields using the "square-root" method.

  17. Using 12 MeV electron beams to develop silicon P +NN + high frequency rectifying diodes

    NASA Astrophysics Data System (ADS)

    Desheng, Hang; Qiji, Lai; Yi, Shi; Zheng, Zheng

    2000-12-01

    Twelve MeV electron beams were used to irradiate common P +NN + diodes (1 A and 1 kV) in order to transfer them into high frequency rectifying ones. Some interesting results have been obtained. It seems that this method is superior to the traditional gold-doping technique in controlling precisely the lives of the minority carriers. Compared with the later electron beam irradiation made the reverse recovery time ( trr) and FWD-voltage ( VF) of the diodes better consistent and repeatable. The high temperature performance was also obviously improved. The qualified rate of diodes was enhanced by more than 30%.

  18. 5 MeV Mott polarimeter for rapid precise electron beam polarization measurements

    SciTech Connect

    Price, J.S.; Poelker, B.M.; Sinclair, C.K.

    1997-11-01

    Low energy (E{sub k} = 100 keV) Mott scattering polarimeters are ill-suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections; measured rates scale to 1 kHz/{mu}A with a 1 {mu}m thick gold target foil.

  19. Beam tracking simulation in the central region of a 13 MeV PET cyclotron

    NASA Astrophysics Data System (ADS)

    Anggraita, Pramudita; Santosa, Budi; Taufik, Mulyani, Emy; Diah, Frida Iswinning

    2012-06-01

    This paper reports the trajectories simulation of proton beam in the central region of a 13 MeV PET cyclotron, operating with negative proton beam (for easier beam extraction using a stripper foil), 40 kV peak accelerating dee voltage at fourth harmonic frequency of 77.88 MHz, and average magnetic field of 1.275 T. The central region covers fields of 240mm × 240mm × 30mm size at 1mm resolution. The calculation was also done at finer 0.25mm resolution covering fields of 30mm × 30mm × 4mm size to see the effects of 0.55mm horizontal width of the ion source window and the halted trajectories of positive proton beam. The simulations show up to 7 turns of orbital trajectories, reaching about 1 MeV of beam energy. The distribution of accelerating electric fields and magnetic fields inside the cyclotron were calculated in 3 dimension using Opera3D code and Tosca modules for static magnetic and electric fields. The trajectory simulation was carried out using Scilab 5.3.3 code.

  20. Low energy, high power hydrogen neutral beam for plasma heating

    NASA Astrophysics Data System (ADS)

    Deichuli, P.; Davydenko, V.; Ivanov, A.; Korepanov, S.; Mishagin, V.; Smirnov, A.; Sorokin, A.; Stupishin, N.

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  1. Automated Calculation of DIII-D Neutral Beam Availability

    SciTech Connect

    Phillips, J.C.; Hong, R.M.; Scoville, B.G.

    1999-11-01

    The neutral beam systems for the DIII-D tokamak are an extremely reliable source of auxiliary plasma heating, capable of supplying up to 20 MW of injected power, from eight separate beam sources into each tokamak discharge. The high availability of these systems for tokamak operations is sustained by careful monitoring of performance and following up on failures. One of the metrics for this performance is the requested injected power profile as compared to the power profile delivered for a particular pulse. Calculating this was a relatively straightforward task, however innovations such as the ability to modulate the beams and more recently the ability to substitute an idle beam for one which has failed during a plasma discharge, have made the task very complex. For example, with this latest advance it is possible for one or more beams to have failed, yet the delivered power profile may appear perfect. Availability used to be manually calculated. This paper presents the methods and algorithms used to produce a system which performs the calculations based on information concerning the neutral beam and plasma current waveforms, along with post-discharge information from the Plasma Control System, which has the ability to issue commands for beams in real time. Plots representing both the requested and actual power profiles, along with statistics, are automatically displayed and updated each shot, on a web-based interface viewable both at DIII-D and by our remote collaborators using no-cost software.

  2. Low energy, high power hydrogen neutral beam for plasma heating

    SciTech Connect

    Deichuli, P.; Davydenko, V.; Ivanov, A. Mishagin, V.; Sorokin, A.; Stupishin, N.; Korepanov, S.; Smirnov, A.

    2015-11-15

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  3. Low energy, high power hydrogen neutral beam for plasma heating.

    PubMed

    Deichuli, P; Davydenko, V; Ivanov, A; Korepanov, S; Mishagin, V; Smirnov, A; Sorokin, A; Stupishin, N

    2015-11-01

    A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase the efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.

  4. Optimization of Electron Beam Transport for a 3-MeV DC Accelerator

    NASA Astrophysics Data System (ADS)

    Baruah, S.; Bhattacharjee, D.; Tiwari, R.; Sahu, G. K.; Thakur, K. B.; Mittal, K. C.; Gantayet, L. M.

    2012-11-01

    Transport of a low-current-density electron beam is simulated for an electrostatic accelerator system. Representative charged particles are uniformly assigned for emission from a circular indirectly-heated cathode of an axial electron gun. The beam is accelerated stepwise up to energy of 1 MeV electrostatically in a length-span of ~3 m using multiple accelerating electrodes in a column of ten tubes. The simulation is done under relativistic condition and the effect of the magnetic field induced by the cathode-heating filament current is taken into account. The beam diameter is tracked at different axial locations for various settings of the electrode potentials. Attempts have been made to examine and explain data on beam transport efficiency obtained from experimental observations.

  5. Development of a lithium liquid metal ion source for MeV ion beam analysis

    SciTech Connect

    Read, P.M.; Maskrey, J.T.; Alton, G.D.

    1988-01-01

    Lithium liquid metal ion sources are an attractive complement to the existing gaseous ion sources that are extensively used for ion beam analysis. This is due in part to the high brightness of the liquid metal ion source and in part to the availability of a lithium ion beam. High brightness is of particular importance to MeV ion microprobes which are now approaching current density limitations on targets determined by the ion source. The availability of a lithium beam provides increased capabilities for hydrogen profiling and high resolution Rutherford backscattering spectrometry. This paper describes the design and performance of a lithium liquid metal ion source suitable for use on a 5MV Laddertron accelerator. Operational experience with the source and some of its uses for ion beam analysis are discussed. 8 refs., 2 figs.

  6. Laser driven MeV proton beam focussing by auto-charged electrostatic lens configuration

    NASA Astrophysics Data System (ADS)

    Kar, S.; Markey, K.; Simpson, P. T.; Bellei, C.; Green, J. S.; Nagel, S. R.; Kneip, S.; Carroll, D. C.; Dromey, B.; Willingale, L.; Clark, E. L.; McKenna, P.; Najmudin, Z.; Krushelnick, K.; Norreys, P.; Clarke, R. J.; Neely, D.; Borghesi, M.; Schiavi, A.; Zepf, M.

    2008-06-01

    Significant reduction of inherent large divergence of the laser driven MeV proton beams is achieved by strong (of the order of 109 V/m) electrostatic focussing field generated in the confined region of a suitably shaped structure attached to the proton generating foil. The scheme exploits the positively charging of the target following an intense laser interaction. Reduction in the proton beam divergence, and commensurate increase in proton flux is observed while preserving the beam laminarity. The underlying mechanism has been established by the help of particle tracing simulations. Dynamic focussing power of the lens, mainly due to the target discharging, can also be exploited in order to bring up the desired chromaticity of the lens for the proton beams of broad energy range.

  7. Measurements of the Argonne Wakefield Accelerator's low charge, 4 MeV RF photocathode witness beam.

    SciTech Connect

    Power, J.

    1998-04-01

    The Argonne Wakefield Accelerator's (AWA) witness RF photocathode gun produced its first electron beam in April of 1996. We have characterized the charge, energy, emittance and bunch length of the witness beam over the last several months. The emittance Was measured by both a quad scan that fitted for space charge using an in house developed Mathematica routine and a pepper pot technique. The bunch length was measured by imaging Cherenkov light from a quartz plate to a Hamamatsu streak camera with 2 psec resolution. A beam energy of 3.9 Mev was measured with a 6 inch round pole spectrometer while a beam charge was measured with both an ICT and a Faraday Cup. Although the gun will normally be run at 100 pC it has produced charges from 10 pC to 4 nc. All results of the measurements to date are presented here.

  8. TFTR (Tokamak Fusion Test Reactor) neutral beam injected power measurement

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Dudek, L.E.; Gammel, G.M.; Johnson, G.A.; Kugel, H.W.; Lagin, L.; O'Connor, T.E.; Shah, P.A.; Sichta, P.

    1989-05-01

    Energy flow within TFTR neutral beamlines is measured with a waterfall calorimetry system capable of simultaneously measuring the energy deposited within four heating beamlines (three ion sources each), or of measuring the energy deposited in a separate neutral beam test stand. Of the energy extracted from the ion source in the well instrumented test stand, 99.5 +- 3.5% can be accounted for. When the ion deflection magnet is energized, however, 6.5% of the extracted energy is lost. This loss is attributed to a spray of devious particles onto unmonitored surfaces. A 30% discrepancy is also observed between energy measurements on the internal beamline calorimeter and energy measurements on a calorimeter located in the test stand target chamber. Particle reflection from the flat plate calorimeter in the target chamber, which the incident beam strikes at a near-grazing angle of 12/degree/, is the primary loss of this energy. A slight improvement in energy accountability is observed as the beam pulse length is increased. This improvement is attributed to systematic error in the sensitivity of the energy measurement to small fluctuations on the supply water temperature. An overall accuracy of 15% is estimated for the total power injected into TFTR. Contributions to this error are uncertainties in the beam neutralization efficiency, reionization and beam scrape-off in the drift duct, and fluctuations in the temperature of the supply water. 28 refs., 9 figs., 1 tab.

  9. Commissioning of heating neutral beams for COMPASS-D tokamak

    SciTech Connect

    Deichuli, P.; Davydenko, V.; Belov, V.; Gorbovsky, A.; Dranichnikov, A.; Ivanov, A.; Sorokin, A.; Mishagin, V.; Abdrashitov, A.; Kolmogorov, V.; Kondakov, A.

    2012-02-15

    Two neutral beam injectors have been developed for plasma heating on COMPASS-D tokamak (Institute of Plasma Physics, Prague). The 4-electrodes multihole ion-optical system with beam focusing was chosen to provide the low divergence 300 kW power in both deuterium and hydrogen atoms. The accelerating voltage is 40 kV at extracted ion current up to 15 A. The power supply system provides the continuous and modulated mode of the beam injection at a maximal pulse length 300 ms. The optimal arrangement of the cryopanels and the beam duct elements provides sufficiently short-length beamline which reduces the beam losses. The evolution of the impurities and molecular fraction content is studied in the process of the high voltage conditioning of the newly made ion sources. Two injectors of the same type have been successfully tested and are ready for operation at tokamak in IPP, Prague.

  10. Focused beams of fast neutral atoms in glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Grigoriev, S. N.; Melnik, Yu. A.; Metel, A. S.; Volosova, M. A.

    2017-06-01

    Glow discharge with electrostatic confinement of electrons in a vacuum chamber allows plasma processing of conductive products in a wide pressure range of p = 0.01 - 5 Pa. To assist processing of a small dielectric product with a concentrated on its surface beam of fast neutral atoms, which do not cause charge effects, ions from the discharge plasma are accelerated towards the product and transformed into fast atoms. The beam is produced using a negatively biased cylindrical or a spherical grid immersed in the plasma. Ions accelerated by the grid turn into fast neutral atoms at p > 0.1 Pa due to charge exchange collisions with gas atoms in the space charge sheaths adjoining the grid. The atoms form a diverging neutral beam and a converging beam propagating from the grid in opposite directions. The beam propagating from the concave surface of a 0.24-m-wide cylindrical grid is focused on a target within a 10-mm-wide stripe, and the beam from the 0.24-m-diameter spherical grid is focused within a 10-mm-diameter circle. At the bias voltage U = 5 kV and p ˜ 0.1 Pa, the energy of fast argon atoms is distributed continuously from zero to eU ˜ 5 keV. The pressure increase to 1 Pa results in the tenfold growth of their equivalent current and a decrease in the mean energy by an order of magnitude, which substantially raises the efficiency of material etching. Sharpening by the beam of ceramic knife-blades proved that the new method for the generation of concentrated fast atom beams can be effectively used for the processing of dielectric materials in vacuum.

  11. Plasma-parameter measurements using neutral-particle-beam attenuation

    SciTech Connect

    Foote, J H; Molvik, A W; Turner, W C

    1982-07-07

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane.

  12. Spheromak Energy Transport Studies via Neutral Beam Injection

    SciTech Connect

    McLean, H S; Hill, D N; Wood, R D; Jayakumar, J; Pearlstein, L D

    2008-02-11

    Results from the SSPX spheromak experiment provide strong motivation to add neutral beam injection (NBI) heating. Such auxiliary heating would significantly advance the capability to study the physics of energy transport and pressure limits for the spheromak. This LDRD project develops the physics basis for using NBI to heat spheromak plasmas in SSPX. The work encompasses three activities: (1) numerical simulation to make quantitative predictions of the effect of adding beams to SSPX, (2) using the SSPX spheromak and theory/modeling to develop potential target plasmas suitable for future application of neutral beam heating, and (3) developing diagnostics to provide the measurements needed for transport calculations. These activities are reported in several publications.

  13. Measurement of diagnostic neutral beam parameters on J-TEXT.

    PubMed

    Wang, J R; Cheng, Z F; Li, Z; Li, Y; Luo, J; Zhang, X L; Zhuang, G

    2016-11-01

    A Doppler frequency shift spectrum (DFSS) system composed of two spectrometers has been developed for the joint Texas experimental tokamak to measure diagnostic neutral beam parameters including the beam energy fractions, intensity distributions, and divergences. The beam energy fractions are derived from measurements of H-alpha (Hα) emission using collisional excitation cross sections. The beam intensity distributions are obtained using an 11-channel measurement with a reconstruction technique. The beam divergences are obtained from spectrum broadening and geometric calculations. The results of preliminary investigations indicate that the DFSS system works well and can be used to obtain all of these parameters simultaneously. According to the preliminary experiment, the one-third energy fraction has the largest proportion (about 45%) of the beam energy and the full energy fraction is about 10%. The beam diameter is about 8.1 cm at a distance of 2.04 m from the accelerator. The beam divergence angle is about 3.3°. The current beam parameters are insufficient for charge-exchange measurements.

  14. Measurement of diagnostic neutral beam parameters on J-TEXT

    NASA Astrophysics Data System (ADS)

    Wang, J. R.; Cheng, Z. F.; Li, Z.; Li, Y.; Luo, J.; Zhang, X. L.; Zhuang, G.

    2016-11-01

    A Doppler frequency shift spectrum (DFSS) system composed of two spectrometers has been developed for the joint Texas experimental tokamak to measure diagnostic neutral beam parameters including the beam energy fractions, intensity distributions, and divergences. The beam energy fractions are derived from measurements of H-alpha (Hα) emission using collisional excitation cross sections. The beam intensity distributions are obtained using an 11-channel measurement with a reconstruction technique. The beam divergences are obtained from spectrum broadening and geometric calculations. The results of preliminary investigations indicate that the DFSS system works well and can be used to obtain all of these parameters simultaneously. According to the preliminary experiment, the one-third energy fraction has the largest proportion (about 45%) of the beam energy and the full energy fraction is about 10%. The beam diameter is about 8.1 cm at a distance of 2.04 m from the accelerator. The beam divergence angle is about 3.3°. The current beam parameters are insufficient for charge-exchange measurements.

  15. Measurement of diagnostic neutral beam parameters on J-TEXT

    SciTech Connect

    Wang, J. R.; Cheng, Z. F. Li, Z.; Li, Y.; Luo, J.; Zhang, X. L.; Zhuang, G.

    2016-11-15

    A Doppler frequency shift spectrum (DFSS) system composed of two spectrometers has been developed for the joint Texas experimental tokamak to measure diagnostic neutral beam parameters including the beam energy fractions, intensity distributions, and divergences. The beam energy fractions are derived from measurements of H-alpha (Hα) emission using collisional excitation cross sections. The beam intensity distributions are obtained using an 11-channel measurement with a reconstruction technique. The beam divergences are obtained from spectrum broadening and geometric calculations. The results of preliminary investigations indicate that the DFSS system works well and can be used to obtain all of these parameters simultaneously. According to the preliminary experiment, the one-third energy fraction has the largest proportion (about 45%) of the beam energy and the full energy fraction is about 10%. The beam diameter is about 8.1 cm at a distance of 2.04 m from the accelerator. The beam divergence angle is about 3.3°. The current beam parameters are insufficient for charge-exchange measurements.

  16. Investigation of accelerated neutral atom beams created from gas cluster ion beams

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, A.; Kirkpatrick, S.; Walsh, M.; Chau, S.; Mack, M.; Harrison, S.; Svrluga, R.; Khoury, J.

    2013-07-01

    A new concept for ultra-shallow processing of surfaces known as accelerated neutral atom beam (ANAB) technique employs conversion of energetic gas cluster ions produced by the gas cluster ion beam (GCIB) method into intense collimated beams of coincident neutral gas atoms having controllable average energies from less than 10 eV per atom to beyond 100 eV per atom. A beam of accelerated gas cluster ions is first produced as is usual in GCIB, but conditions within the source ionizer and extraction regions are adjusted such that immediately after ionization and acceleration the clusters undergo collisions with non-ionized gas atoms. Energy transfer during these collisions causes the energetic cluster ions to release many of their constituent atoms. An electrostatic deflector is then used to eliminate charged species, leaving the released neutral atoms to still travel collectively at the same velocities they had as bonded components of their parent clusters. Upon target impact, the accelerated neutral atom beams produce effects similar to those normally associated with GCIB, but to shallower depths, with less surface damage and with superior subsurface interfaces. The paper discusses generation and characterization of the accelerated neutral atom beams, describes interactions of the beams with target surfaces, and presents examples of ongoing work on applications for biomedical devices.

  17. Target irradiation facility and targetry development at 160 MeV proton beam of Moscow linac

    NASA Astrophysics Data System (ADS)

    Zhuikov, Boris L.; Kokhanyuk, Vladimir M.; Konyakhin, Nickolay A.; Vincent, John

    1999-12-01

    A facility has been built and successfully operated with the 160 MeV proton beam of Moscow Meson factory LINAC, Institute for Nuclear Research (INR) of Russian Academy of Science, Troitsk. The facility was created for various isotope production goals as well as for fundamental nuclear investigations at high intensity beam (100 μA and more). An important part of the facility targetry system is a high-intensity beam monitoring collimator device. Measurements of the temperature distribution between collimator sectors, cooling water flow and temperature, and the beam current, provide an opportunity to compute beam losses and beam position. The target holder design allows easy insertion by manipulator and simultaneous bombardment of several different targets of various types and forms, and variation of proton energy on each target over a wide range below 160 MeV. The main target utilized for commercial 82Sr isotope production is metallic rubidium in a stainless-steel container. A regular wet chemistry method has been used in this process to recover radio-strontium. A new targetry technique based on adsorption of radio-strontium from liquid metallic rubidium has been explored and is under development. It was found that strontium may be extracted from molten rubidium on several metallic or oxide flat surfaces, with the temperature of the sorbing material about 130-170°C, and the temperature of the vessel with metallic rubidium about 240-270°C. This makes it possible to provide "on-line" 82Sr production and extraction on a very high intensity beam with the use of circulating liquid rubidium targets. The same idea has been found to be fruitful to extract "on-line" and selectively a number of radionuclides directly from liquid lead targets by chemosorption processes.

  18. Long Plasma Source for Heavy Ion Beam Charge Neutralization

    SciTech Connect

    Efthimion, P.C.; Gilson, E.P.; Grisham, L.; Davidson, R.C.; Logan, B.G.; Seidl, P.A.; Waldron, W.

    2008-06-01

    Plasmas are a source of unbound electrons for charge neutralizing intense heavy ion beams to focus them to a small spot size and compress their axial length. The plasma source should operate at low neutral pressures and without strong externally-applied fields. To produce long plasma columns, sources based upon ferroelectric ceramics with large dielectric coefficients have been developed. The source utilizes the ferroelectric ceramic BaTiO{sub 3} to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) is covered with ceramic material. High voltage ({approx} 8 kV) is applied between the drift tube and the front surface of the ceramics. A BaTiO{sub 3} source comprised of five 20-cm-long sources has been tested and characterized, producing relatively uniform plasma in the 5 x 10{sup 10} cm{sup -3} density range. The source was integrated into the NDCX device for charge neutralization and beam compression experiments, and yielded current compression ratios {approx} 120. Present research is developing multi-meter-long and higher density sources to support beam compression experiments for high energy density physics applications.

  19. Neutralization of beam-emitting spacecraft by plasma injection

    NASA Technical Reports Server (NTRS)

    Sasaki, S.; Kawashima, N.; Kuriki, K.; Yanagisawa, M.; Obayashi, T.; Roberts, W. T.; Reasoner, D. L.; Taylor, W. W. L.

    1987-01-01

    An impulsive plasma injection has been used to study charge neutralization of the Space Shuttle Orbiter while it was emitting an electron beam into space. This investigation was performed by Space Experiments with Particle Accelerators on Spacelab-1. A plasma consisting of 10 to the 19th argon ion-electron pairs was injected into space for 1 ms while an electron beam was also being emitted into space. The electron beam energy and current were as high as 5 keV and 300 mA. While the orbiter potential was positive before the plasma injection and began to decrease during the plasma injection, it was near zero for 6 to 20 ms after the plasma injection. The recovery time to the initial level of charging varied from 10 to 100 ms. In a laboratory test in a large space chamber using the same flight hardware, the neutralization time was 8-17 ms and the recovery time was 11-20 ms. The long duration of the neutralization effect in space can be explained by a model of diffusion of the cold plasma which is produced near the Orbiter by charge exchange between the neutral argon atoms and the energetic argon ions during plasma injection.

  20. Beam tests on the 4-kA, 1. 5-MeV injector for FXR

    SciTech Connect

    Kulke, B.; Kihara, R.; Ravenscroft, D.; Scarpetti, R.; Vogtlin, G.

    1981-01-01

    The new flash x-ray machine (FXR) at Lawrence Livermore National Laboratory is scheduled for completion in late 1981. This is a 54 module, linear induction accelertor, designed to deliver 500 Roentgen at 1 m as bremsstrahlung from a 20 MeV, 4 kA, 60 ns pulsed electron beam. The 9 cm diameter, cold-cathode electron source generates a 15 kA emitted beam at 1.5 MeV, and collimation is being used to reduce the transmitted current to 3.5 kA, with an emittance of 70 mr-cm. The collimated beam diameter is 4 cm. Six ferrite-loaded cavities are used in tandem to energize the injector. The high voltage performance of the injector cavities and other pulsed-power conditioning elements was tested earlier in a series of 10/sup 5/ shots at 400 kV per cavity. An overview of the injector design and of the beam test results is given.

  1. Production of α-particle emitting 211At using 45 MeV α-beam

    NASA Astrophysics Data System (ADS)

    Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

    2014-06-01

    Among the α-particle emitting radionuclides, 211At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of 211At are less than 70 µm in water with a linear energy transfer between 100 and 130 keV µm-1, which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce 211At. The direct production method is based on the nuclear reactions 209Bi(α,2n)211At. Production of the radionuclide 211At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the α-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate α-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an Eα, av of 29.17 MeV, the very small contribution of 210At confirms the right choice of the irradiation energy to obtain a pure production of 211At isotope.

  2. Results of Beam Extraction Performance for the KSTAR Neutral Beam Injector

    NASA Astrophysics Data System (ADS)

    Chang, Doo-Hee; Jeong, Seung Ho; Kim, Tae-Seong; Lee, Kwang Won; Ryul In, Sang; Jin, Jung-Tae; Chang, Dae-Sik; Oh, Byung-Hoon; Bae, Young-Soon; Kim, Jong-Su; Cho, Wook; Park, Hyun-Taek; Park, Young-Min; Yang, Hyung-Lyeol; Watanabe, Kazuhiro; Dairaku, Masayuki; Tobari, Hiroyuki; Kashiwagi, Mieko; Hanada, Masaya; Inoue, Takashi

    2011-06-01

    The first neutral beam injector (NBI-1) has been developed for the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. The first long pulse ion source (LPIS-1) has been installed on the NBI-1 for an auxiliary heating and current drive of KSTAR plasmas. The performance of ion and neutral beam extractions in the LPIS-1 was investigated initially on the KSTAR NBI-1 system, prior to the neutral beam injection into the main plasmas. The ion source consists of a magnetic bucket plasma generator with multipole cusp fields and a set of prototype tetrode accelerators with circular apertures. The inner volume of the plasma generator and accelerator column in the LPIS-1 is approximately 123 L. Design requirements for the ion source were a 120 kV/65 A deuterium beam and a 300 s pulse length. The extraction of ion beams was initiated by the formation of arc plasmas in the LPIS-1, called the arc-beam extraction method. A stable ion beam extraction of the LPIS-1 was achieved up to 85 kV/32 A for a 5 s pulse length and 80 kV/25 A for a 14 s pulse length. An optimum beam perveance of 1.15 µperv was observed at an acceleration voltage of 60 kV. Neutralization efficiency was measured by a water-flow calorimetry (WFC) method using a calorimeter and the operation of a bending magnet. The full-energy species of ion beams were detected by using the diagnostic method of optical multichannel analyzer (OMA). An arc efficiency of the LPIS was 0.6-1.1 A/kW depending on the operating conditions of arc discharge. A neutral beam power of ˜1.0 MW must be sufficiently injected into the KSTAR plasmas from the LPIS-1 at a beam energy of 80 keV.

  3. The ITER Neutral Beam Test Facility towards SPIDER operation

    NASA Astrophysics Data System (ADS)

    Toigo, V.; Dal Bello, S.; Gaio, E.; Luchetta, A.; Pasqualotto, R.; Zaccaria, P.; Bigi, M.; Chitarin, G.; Marcuzzi, D.; Pomaro, N.; Serianni, G.; Agostinetti, P.; Agostini, M.; Antoni, V.; Aprile, D.; Baltador, C.; Barbisan, M.; Battistella, M.; Boldrin, M.; Brombin, M.; Dalla Palma, M.; De Lorenzi, A.; Delogu, R.; De Muri, M.; Fellin, F.; Ferro, A.; Gambetta, G.; Grando, L.; Jain, P.; Maistrello, A.; Manduchi, G.; Marconato, N.; Pavei, M.; Peruzzo, S.; Pilan, N.; Pimazzoni, A.; Piovan, R.; Recchia, M.; Rizzolo, A.; Sartori, E.; Siragusa, M.; Spada, E.; Spagnolo, S.; Spolaore, M.; Taliercio, C.; Valente, M.; Veltri, P.; Zamengo, A.; Zaniol, B.; Zanotto, L.; Zaupa, M.; Boilson, D.; Graceffa, J.; Svensson, L.; Schunke, B.; Decamps, H.; Urbani, M.; Kushwah, M.; Chareyre, J.; Singh, M.; Bonicelli, T.; Agarici, G.; Garbuglia, A.; Masiello, A.; Paolucci, F.; Simon, M.; Bailly-Maitre, L.; Bragulat, E.; Gomez, G.; Gutierrez, D.; Mico, G.; Moreno, J.-F.; Pilard, V.; Chakraborty, A.; Baruah, U.; Rotti, C.; Patel, H.; Nagaraju, M. V.; Singh, N. P.; Patel, A.; Dhola, H.; Raval, B.; Fantz, U.; Fröschle, M.; Heinemann, B.; Kraus, W.; Nocentini, R.; Riedl, R.; Schiesko, L.; Wimmer, C.; Wünderlich, D.; Cavenago, M.; Croci, G.; Gorini, G.; Rebai, M.; Muraro, A.; Tardocchi, M.; Hemsworth, R.

    2017-08-01

    SPIDER is one of two projects of the ITER Neutral Beam Test Facility under construction in Padova, Italy, at the Consorzio RFX premises. It will have a 100 keV beam source with a full-size prototype of the radiofrequency ion source for the ITER neutral beam injector (NBI) and also, similar to the ITER diagnostic neutral beam, it is designed to operate with a pulse length of up to 3600 s, featuring an ITER-like magnetic filter field configuration (for high extraction of negative ions) and caesium oven (for high production of negative ions) layout as well as a wide set of diagnostics. These features will allow a reproduction of the ion source operation in ITER, which cannot be done in any other existing test facility. SPIDER realization is well advanced and the first operation is expected at the beginning of 2018, with the mission of achieving the ITER heating and diagnostic NBI ion source requirements and of improving its performance in terms of reliability and availability. This paper mainly focuses on the preparation of the first SPIDER operations—integration and testing of SPIDER components, completion and implementation of diagnostics and control and formulation of operation and research plan, based on a staged strategy.

  4. Trends and applications for MeV electrostatic ion beam accelerators

    NASA Astrophysics Data System (ADS)

    Norton, G. A.; Stodola, S. E.

    2014-08-01

    The 1970s into the 1980s saw a major broadening of applications for electrostatic accelerators. Prior to this time, all accelerators were used primarily for nuclear structure research. In the 70s there was a significant move into production ion implantation with the necessary MeV ion beam analysis techniques such as RBS and ERD. Accelerators are still being built for these materials analysis techniques today. However, there is still a great ongoing expansion of applications for these machines. At the present time, the demand for electrostatic accelerators is near an all time high. The number of applications continues to grow. This paper will touch on some of the current applications which are as diverse as nuclear fission reactor developments and pharmacokinetics. In the field of nuclear engineering, MeV ion beams from electrostatic accelerators are being used in material damage studies and for iodine and actinide accelerator mass spectrometry (AMS). In the field of pharmacokinetics, electrostatic MeV accelerators are being used to detect extremely small amounts of above background 14C. This has significantly reduced the time required to reach first in human studies. These and other applications will be discussed.

  5. Guiding of 4 MeV C+ and C4+ ion beams using cylindrical glass channel

    NASA Astrophysics Data System (ADS)

    Motohashi, Kenji; Miyawaki, Nobumasa; Saitoh, Yuichi; Narumi, Kazumasa; Matoba, Shiro

    2017-04-01

    To investigate how the initial charge state affects the transmission of 4 MeV C+ and C4+ ion beams through a channel, we measured the transmission probability and kinetic energy of atoms and ions that pass through a cylindrical channel in glass, such as a narrow gap between a cylindrical convex glass surface and a cylindrical concave glass surface. Kinetic energy distributions were measured at three typical observation angles φ with the cylindrical glass channel tilted at angles θ = ‑3, ‑2, ‑1, 0, 1, 2, and 3° with respect to the incident ion beam. The ion beam is guided in both initial charge states; that is, the transmission maintains the initial kinetic energy at tilt angles greater than the geometric limit. However, no marked difference in transmission appears between the two initial charge states.

  6. Experimental Characterization of the Transverse Phase Space of a 60-MeV Electron Beam Through a Compressor Chicane

    SciTech Connect

    Zhou, F.; Kabel, A.; Rosenzweig, J.; Agustsson, R.; Andonian, G.; Cline, D.; Murokh, A.; Yakimenko, V.; /UCLA /SLAC /Brookhaven

    2007-02-12

    Space charge and coherent synchrotron radiation may deteriorate electron beam quality when the beam passes through a magnetic bunch compressor. This paper presents the transverse phase-space tomographic measurements for a compressed beam at 60 MeV, around which energy the first stage of magnetic bunch compression takes place in most advanced linacs. Transverse phase-space bifurcation of a compressed beam is observed at that energy, but the degree of the space charge-induced bifurcation is appreciably lower than the one observed at 12 MeV.

  7. Visualization experiment of 30 MeV proton beam irradiated water target

    NASA Astrophysics Data System (ADS)

    Hwan Hong, Bong; Gun Yang, Tea; Su Jung, In; Soo Park, Yeun; Hee Cho, Hyung

    2011-11-01

    The nucleate boiling phenomena in a water target irradiated by 30 MeV proton beam were visualized experimentally. The beam size was 10 mm in diameter and beam current of 10, 15 and 20 μA were used, respectively. A target cavity of 4.5 cc in volume was filled with distilled water without atmosphere. A CMOS camera is used to record the phenomena through a side window. The temperature and pressure were measured during experiments. The depth of the Bragg peak was indicated by the blue light emission of the proton beam in the water target. In the case of 10 μA beam intensity, there was no visible phase change but fluxes by convection was observed at the Bragg peak and near the foil surface region. At 15 μA beam intensity, steam bubbles were generated by homogenous nuclear boiling at the Bragg peak and corrupted by cavitation at the upper region. The steam bubble generation point can be indicated by the blue light emission, which can show us the position of the Bragg peak. At 20 μΑ beam intensity, the steam bubbles were generated at Bragg peak and near the foil surface. The homogenous nucleate boiling at the Bragg peak was dominant and the heterogeneous nucleate boiling near the foil surface took place, occasionally. The cavitation of the steam bubble was also observed in the upper region within the target. The penetration depth of the proton beam was change along with the steam bubble formation. The blue light emission of the proton beam in water shows that the penetration depth of the proton beam becomes deeper when vapor bubbles are generated.

  8. New ion source for KSTAR neutral beam injection system.

    PubMed

    Kim, Tae-Seong; Jeong, Seung Ho; In, Sang-Ryul

    2012-02-01

    The neutral beam injection system (NBI-1) of the KSTAR tokamak can accommodate three ion sources; however, it is currently equipped with only one prototype ion source. In the 2010 and 2011 KSTAR campaigns, this ion source supplied deuterium neutral beam power of 0.7-1.6 MW to the KSTAR plasma with a beam energy of 70-100 keV. A new ion source will be prepared for the 2012 KSTAR campaign with a much advanced performance compared with the previous one. The newly designed ion source has a very large transparency (∼56%) without deteriorating the beam optics, which is designed to deliver a 2 MW injection power of deuterium beams at 100 keV. The plasma generator of the ion source is of a horizontally cusped bucket type, and the whole inner wall, except the cathode filaments and plasma grid side, functions as an anode. The accelerator assembly consists of four multi-circular aperture grids made of copper and four electrode flanges made of aluminum alloy. The electrodes are insulated using PEEK. The ion source will be completed and tested in 2011.

  9. 3D-Printed Beam Splitter for Polar Neutral Molecules

    NASA Astrophysics Data System (ADS)

    Gordon, Sean D. S.; Osterwalder, Andreas

    2017-04-01

    We describe a macroscopic beam splitter for polar neutral molecules. A complex electrode structure is required for the beam splitter which would be very difficult to produce with traditional manufacturing methods. Instead, we make use of a nascent manufacturing technique: 3D printing of a plastic piece, followed by electroplating. This fabrication method opens a plethora of avenues for research, since 3D printing imposes practically no limitations on possible shapes, and the plating produces chemically robust, conductive construction elements with an almost free choice of surface material. It has the added advantage of dramatically reduced production cost and time. Our beam splitter is an electrostatic hexapole guide that smoothly transforms into two bent quadrupoles. We demonstrate the correct functioning of this device by separating a supersonic molecular beam of ND3 into two correlated fractions. It is shown that this device can be used to implement experiments with differential detection wherein one of the fractions serves as a probe and the other as a reference. Reverse operation would allow the merging of two beams of polar neutral molecules.

  10. 8MVA modulator/regulator for neutral beams

    SciTech Connect

    Remsen, D.B. Jr.; Overett, T.H.

    1980-05-01

    This paper describes very generally the modulator/regulator (Mod/Reg) being built for Transrex by Systems, Science and Software for use on the neutral beam power supplies that Transrex is building for General Atomic Company to power the neutral beam heating systems that will be used on the Doublet III fusion device. The Mod/Reg is required to provide an 80 kV, 100 A pulse for a second every 90 sec. The voltage is to be regulated to 3%, and in case of fault the pulse must be interrupted within 10 ..mu..sec. An additional requirement was that the total system have very low capacity such that the total energy stored would be less than 15 joules. This is a restriction imposed by the source designer to prevent destroying the source in case of an arc within the source.

  11. Modeling activities on the negative-ion-based Neutral Beam Injectors of the Large Helical Device

    SciTech Connect

    Agostinetti, P.; Antoni, V.; Chitarin, G.; Pilan, N.; Serianni, G.; Veltri, P.; Cavenago, M.; Nakano, H.; Takeiri, Y.; Tsumori, K.

    2011-09-26

    At the National Institute for Fusion Science (NIFS) large-scaled negative ion sources have been widely used for the Neutral Beam Injectors (NBIs) mounted on the Large Helical Device (LHD), which is the world-largest superconducting helical system. These injectors have achieved outstanding performances in terms of beam energy, negative-ion current and optics, and represent a reference for the development of heating and current drive NBIs for ITER.In the framework of the support activities for the ITER NBIs, the PRIMA test facility, which includes a RF-drive ion source with 100 keV accelerator (SPIDER) and a complete 1 MeV Neutral Beam system (MITICA) is under construction at Consorzio RFX in Padova.An experimental validation of the codes has been undertaken in order to prove the accuracy of the simulations and the soundness of the SPIDER and MITICA design. To this purpose, the whole set of codes have been applied to the LHD NBIs in a joint activity between Consorzio RFX and NIFS, with the goal of comparing and benchmarking the codes with the experimental data. A description of these modeling activities and a discussion of the main results obtained are reported in this paper.

  12. Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

    SciTech Connect

    Castracane, J.

    2001-01-04

    The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies.

  13. Comparison of laser and neutral particle beam discrimination

    NASA Astrophysics Data System (ADS)

    Canavan, Gregory H.

    1989-09-01

    The relative ability of lasers and neutral particle beams (NPBs) to discriminate reentry vehicle (RV) and anti-satellite (ASAT) decoys is pivotal in assessing their relative worth as strategic defenses. Their ability is evaluated and their relative contributions are assessed. It is concluded that NPBs can typically discriminate about 100 times as many objects as can lasers, and do so with significantly greater certainty.

  14. Comparison of laser and neutral particle beam discrimination

    SciTech Connect

    Canavan, G.H.

    1989-09-01

    The relative ability of lasers and neutral particle beams (NPBs) to discriminate reentry vehicle (RV) and anti-satellite (ASAT) decoys is pivotal in assessing their relative worth as strategic defenses. This report evaluates their ability and assesses their relative contributions, concluding that NPBs can typically discriminate about 100 times as many objects as can lasers, and do so with significantly greater certainty. 7 refs., 2 figs.

  15. High frequency fishbones excited by near perpendicular neutral beam injection

    SciTech Connect

    Zhou Deng

    2006-07-15

    The high frequency fishbone instability observed in experiments with near perpendicular neutral beam injection is interpreted as the ideal internal kink mode destabilized by circulating energetic ions. The mode frequency is close to the transit frequency of circulating ions. The beta value of the circulating ions is required to peak on the magnetic axis and the average value within the q=1 magnetic surface must exceed a critical value for the mode to grow up.

  16. Thick amorphous hums of Ni base alloys using high energy (MeV) ion beam mixing

    NASA Astrophysics Data System (ADS)

    Bhattacharya, R. S.; Pronko, P. P.; Rai, A. K.; McCormick, A. W.; Raffoul, C.

    1985-03-01

    This work investigates the potential for applying ion beam mixing techniques to the fabrication of amorphous metallic alloy coatings of MoNi and TiNi on metal substrates to improve their corrosion resistant properties. Alternating layers of 100 Å Mo and 70 Å Ni with total thicknesses of 1450 Å and 2900 Å were prepared by e-beam evaporation on Ni substrates. Similarly, 80 A Ti and 50 Å Ni alternate layers with total thicknesses of 900 Å and 1560 Å were deposited on Ni. A batch of alternating films of total thickness 5200 Å of TiNi with individual thicknesses of 160 Å Ti and 100 Å Ni were also prepared on Ni substrates. The thicknesses of individual films were adjusted in this way to obtain an overall composition of Ni 50Mo 50 and Ni 50Ti 50 after mixing. The films were irradiated with 1 and 2 MeV Au + and 1.5 MeV Ni + ions depending on the total thickness. The ion beam mixing and nucrostructure of these films have been studied as a function of dose using RBS and TEM. Amorphous layers have been tested for their corrosion behavior by potentiodynamic polarization techniques. Measurements carried out in nitric acid solution reveal that both NiMo and NiTi amorphous layers are more resistant to corrosive attack than the polycrystalline multiphased alloys. NiTi exhibited much superior corrosion resistant properties than NiMo.

  17. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, Henry W.; Hand, Jr, Samuel W.; Ksayian, Haig

    1986-01-01

    For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

  18. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, Henry W.; Hand Jr, Samuel W.; Ksayian, Haig

    1986-02-04

    For use in a tokamak fusion reactor having a midplane magnetic coil on the inner wall of an evacuated toriodal chamber within which a neutral beam heated, fusing plasma is magnetically confined, a neutral beam armor shield and plasma limiter is provided on the inner wall of the toroidal chamber to shield the midplane coil from neutral beam shine-thru and plasma deposition. The armor shield/plasma limiter forms a semicircular enclosure around the midplane coil with the outer surface of the armor shield/plasma limiter shaped to match, as closely as practical, the inner limiting magnetic flux surface of the toroidally confined, indented, bean-shaped plasma. The armor shield/plasma limiter includes a plurality of semicircular graphite plates each having a pair of coupled upper and lower sections with each plate positioned in intimate contact with an adjacent plate on each side thereof so as to form a closed, planar structure around the entire outer periphery of the circular midplane coil. The upper and lower plate sections are adapted for coupling to heat sensing thermocouples and to a circulating water conduit system for cooling the armor shield/plasma limiter.The inner center portion of each graphite plate is adapted to receive and enclose a section of a circular diagnostic magnetic flux loop so as to minimize the power from the plasma confinement chamber incident upon the flux loop.

  19. RF plasma source for heavy ion beam charge neutralization

    SciTech Connect

    Efthimion, Philip C.; Gilson, Erik; Grisham, Larry; Davidson, Ronald C.; Yu, Simon S.; Logan, B. Grant

    2003-05-01

    Highly ionized plasmas are being used as a medium for charge neutralizing heavy ion beams in order to focus the ion beam to a small spot size. A radio frequency (RF) plasma source has been built at the Princeton Plasma Physics Laboratory (PPPL) in support of the joint Neutralized Transport Experiment (NTX) at the Lawrence Berkeley National Laboratory (LBNL) to study ion beam neutralization with plasma. The goal is to operate the source at pressures {approx} 10{sup -5} Torr at full ionization. The initial operation of the source has been at pressures of 10{sup -4}-10{sup -1} Torr and electron densities in the range of 10{sup 8}-10{sup 11} cm{sup -3}. Recently, pulsed operation of the source has enabled operation at pressures in the 10{sup -6} Torr range with densities of 10{sup 11} cm{sup -3}. Near 100% ionization has been achieved. The source has been integrated with the NTX facility and experiments have begun.

  20. Neutral beam interlock system on TFTR using infrared pyrometry

    SciTech Connect

    Medley, S.S.; Kugel, H.W.; Kozub, T.A.; Lowrance, J.L.; Mastrocola, V.; Renda, G.; Young, K.M.

    1986-06-01

    Although the region of the TFTR vacuum vessel wall which is susceptible to damage by neutral beam strike is armored with a mosaic of TiC-clad POCO graphite titles, at power deposition levels above 2.5 kW/cm/sup 2/ the armor surface temperature exceeds 1200/sup 0/C within 250 ms and itself becomes susceptible to damage. In order to protect the wall armor, a neutral beam interlock system based on infrared pyrometry measurement of the armor surface temperature was installed on TFTR. For each beamline, a three-fiber-optic telescope views three areas of approx.30 cm diameter centered on the armor hot spots for the three ion sources. Each signal is fiber-optic coupled to a remote 900 nm pyrometer which feeds analog signals to the neutral beam interrupt circuits. The pyrometer interlock system is designed to interrupt each of the twelve ion sources independently within 10 ms of the temperature exceeding a threshold settable in the range of 500 to 2300/sup 0/C. A description of the pyrometer interlock system and its performance will be presented.

  1. The Negative Ion based Diagnostic Neutral Beam for ITER

    NASA Astrophysics Data System (ADS)

    Schunke, B.; Decamps, H.; Dremel, M.; Hemsworth, R.; Tanga, A.; Bandyophadhyay, M.; Baruah, B.; Chakraborty, A.; Rotti, C.; Shah, S.; Singh, M.; Singh, N.

    2009-11-01

    The ITER dedicated Diagnostic Neutral Beam (DNB) is under construction. It is the basis for the Motional Stark Effect measurements at the ITER plasma edge and charge exchange spectroscopy. The DNB shares many features of the ITER Heating Neutral Beams (HNBs), but will operate only in hydrogen and inject ˜2 MW of 100 keV of H^0 into the ITER plasmas. The same Cs seeded RF negative ion source is used as for the HNBs. The strong influence of the residual fields on the H^- and electrons in the accelerator has led to a new design of the magnetic filter in the ion source. Electron dumps consisting of parallel, vertical, cooled, plates between groups of beamlets immediately downstream of the accelerator prevent excessive electron power reaching the DNB cryopumps. The 4 channel gas neutralizer is made of cooled panels with special protection for the leading edges. Residual ions are deflected electrostatically onto cooled panels based on CuCrZr Heat Transfer Elements. A retractable calorimeter allows commissioning and beam profile measurements. It will be shown how imposed commonalities with the HNBs have influenced the design choices. The baseline DNB operating scenario and the engineering issues (lifetime, fatigue etc.), will be discussed.

  2. Considerations for the development of neutral beam injection for fusion reactors or DEMO

    NASA Astrophysics Data System (ADS)

    Hemsworth, R. S.; Boilson, D.

    2017-08-01

    Neutral beam injection (NBI) has been the most successful heating scheme applied to fusion devices, the majority of which have been based on the acceleration and neutralization in a gas target of accelerated positive ions. For large fusion devices such as ITER, DEMO and fusion reactors, beam energies of the order of 0.5 MeV per nucleon or higher are required to penetrate deeply into the fusing plasma, and thus to heat the plasma in the most important region, i.e. near the poloidal axis of the device, and to drive current in the plasma. Because the efficiency of neutralization of positive ions in a gas target becomes unacceptably low at energies above ≈100 keV/nucleon, future injectors will be based on the neutralization of negative ions, either in a gas target, by photons or in a plasma target. So far only two systems based on negative ions have been used on fusion devices, at JT-60U and at LHD, both based on neutralization in a gas target. The injectors for ITER will also use a gas target, but the energy and operating environment are reactor and DEMO relevant. Also the ITER injectors will have to operate for pulse lengths orders of magnitude higher than all previous NBI systems. In this paper the R&D required for an NBI system for a reactor, or DEMO, is considered against the background of the ITER NBI system development, and the main elements of the required R&D are identified.

  3. Study of the beam-foil excitation mechanism using Cl projectiles, 2 10 MeV

    NASA Astrophysics Data System (ADS)

    Jupén, C.; Denne, B.; Ekberg, J. O.; Engström, L.; Litzén, U.; Martinson, I.; Tai-Meng, W.; Trigueiros, A.; Veje, E.

    1982-11-01

    We have studied beam-foil excitation of chlorine projectiles by means of optical spectrometry, in the projectile energy range 2-10 MeV. This is a preliminary report, concentrating on the 3p and 3d level excitations in Cl VII (sodium-like chlorine) and in Cl VIII (neon-like chlorine). A discussion of the results is given, and it is concluded that the 3p and 3d levels in Cl VII and Cl VIII are populated by the same mechanism, namely molecular-orbital electron promotions.

  4. Plasma based wakefield acceleration using a 46MeV multibunched electron beam

    NASA Astrophysics Data System (ADS)

    Kallos, Efthymios; Ben-Zvi, Ilan; Zhou, Feng; Kimura, Wayne

    2005-10-01

    In the multibunch plasma wakefield acceleration scheme a series of electron microbunches are fed into a high density plasma and resonantly excite a wakefield that can accelerate the beam electrons. Here we present some recent experimental results conducted at Brookhaven's Accelerator test Facility (ATF) where ˜90 microbunches at 46MeV created through the IFEL effect with a 10.6μm CO2 laser interact with a high density 10^19cm-3 12mm long plasma. Some further PIC simulations provide insight into the physics of the interaction.

  5. Production of neutral pions in heavy-ion collisions at Elab/A=25 MeV

    NASA Astrophysics Data System (ADS)

    Young, G. R.; Obenshain, F. E.; Plasil, F.; Braun-Munzinger, P.; Freifelder, R.; Paul, P.; Stachel, J.

    1986-02-01

    Inclusive production of neutral pions was observed at Elab/A=25 MeV in the reactions 16O+Al,Ni-->π0+X. Neutral pions were detected by observing their two decay γ rays in coincidence in an array of 20 Pb-glass Cerenkov-detector telescopes. An array of plastic Cerenkov detectors was added to the above array to tag and reject a significant cosmic-ray background. The observed cross sections are much larger than predicted by nucleon-nucleon collision or statistical models, even if cooperative action of target and projectile nucleons and cluster formation in the final channel are taken into account. This indicates the presence of a collective production mechanism.

  6. Dense Metal Plasma in a Solenoid for Ion Beam Neutralization

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-10-30

    Space-charge neutralization is required to compress and focus a pulsed, high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We described approaches to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons. Among the options are plasma injection from pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means, by an array of movable Langmuir probes, by a small single probe, and by evaluating Stark broadening of the Balmer H beta spectral line. In the main approach described here, the plasma is produced at several cathode spots distributed azimuthally on the ring cathode. It is shown that the plasma is essentially hollow, as determined by the structure of the magnetic field, though the plasma density exceeds 1014 cm-3 in practically all zones of the solenoid volume if the ring electrode is placed a few centimeters off the center of the solenoid. The plasma is non-uniform and fluctuating, however, since its density exceeds the ion beam density it is believed that this approach could provide a practical solution to the space charge neutralization challenge.

  7. First neutral beam injection experiments on KSTAR tokamak.

    PubMed

    Jeong, S H; Chang, D H; Kim, T S; In, S R; Lee, K W; Jin, J T; Chang, D S; Oh, B H; Bae, Y S; Kim, J S; Park, H T; Watanabe, K; Inoue, T; Kashiwagi, M; Dairaku, M; Tobari, H; Hanada, M

    2012-02-01

    The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D(+):D(2)(+):D(3)(+) = 75:20:5 at beam current density of 85 mA/cm(2). The arc efficiency is more than 1.0 A∕kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the T(i) and T(e) profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.

  8. 200-mm-diameter neutral beam source based on inductively coupled plasma etcher and silicon etching

    SciTech Connect

    Kubota, Tomohiro; Nukaga, Osamu; Ueki, Shinji; Sugiyama, Masakazu; Inamoto, Yoshimasa; Ohtake, Hiroto; Samukawa, Seiji

    2010-09-15

    The authors developed a neutral beam source consisting of a 200-mm-diameter inductively coupled plasma etcher and a graphite neutralization aperture plate based on the design of a neutral beam source that Samukawa et al. [Jpn. J. Appl. Phys., Part 2 40, L779 (2001)] developed. They measured flux and energy of neutral particles, ions, and photons using a silicon wafer with a thermocouple and a Faraday cup and calculated the neutralization efficiency. An Ar neutral beam flux of more than 1 mA/cm{sup 2} in equivalent current density and a neutralization efficiency of more than 99% were obtained. The spatial uniformity of the neutral beam flux was within {+-}6% within a 100 mm diameter. Silicon etching using a F{sub 2}-based neutral beam was done at an etch rate of about 47 nm/min, while Cl{sub 2}-based neutral beam realized completely no undercut. The uniformity of etch rate was less than {+-}5% within the area. The etch rate increased by applying bias power to the neutralization aperture plate, which shows that accelerated neutral beam was successfully obtained. These results indicate that the neutral beam source is scalable, making it possible to obtain a large-diameter and uniform neutral beam, which is inevitable for application to mass production.

  9. Neutral beam current drive scaling in DIII-D

    SciTech Connect

    Porter, G.D.; Bhadra, D.K.; Burrell, K.H.; Callis, R.W.; Colleraine, A.P.; Ferron, J.R.; James, R.A.; Kellman, A.G.; Kim, J.; Matsuoka, M.

    1989-03-01

    Neutral beam current drive scaling experiments have been carried out on the DIII-D tokamak at General Atomics. These experiments were performed using up to 10 MW of 80 keV hydrogen beams. Previous current drive experiments on DIII-D have demonstrated beam driven currents up to 340 kA. In the experiments reported here we achieved beam driven currents of at least 500 kA, and have obtained operation with record values of poloidal beta (epsilon..beta../sub p/ = 1.4). The beam driven current reported here is obtained from the total plasma current by subtracting an estimate of the residual Ohmic current determined from the measured loop voltage. In this report we discuss the scaling of the current drive efficiency with plasma conditions. Using hydrogen neutral beams, we find the current drive efficiency is similar in Deuterium and Helium target plasmas. Experiments have been performed with plasma electron temperatures up to T/sub e/ = 3 keV, and densities in the range 2 /times/ 10/sup 19/m/sup /minus/3/ < n/sub e/ < 4 /times/ 10/sup 19/m/sup /minus/3/. The current drive efficiency (nIR/P) is observed to scale linearly with the energy confinement time on DIII-D to a maximum of 0.05 /times/ 10/sup 20/m/sup /minus/2/ A/W. The measured efficiency is consistent with a 0-D theoretical model. In addition to comparison with this simple model, detailed analysis of several shots using the time dependent transport code ONETWO is discussed. This analysis indicates that bootstrap current contributes approximately 10--20% of the the total current. Our estimates of this effect are somewhat uncertain due to limited measurements of the radial profile of the density and temperatures. 4 refs., 1 fig., 1 tab.

  10. Efficient production and diagnostics of MeV proton beams from a cryogenic hydrogen ribbon

    NASA Astrophysics Data System (ADS)

    Velyhan, A.; Giuffrida, L.; Scuderi, V.; Perin, J. P.; Chatain, D.; Garcia, S.; Bonnay, P.; Dostal, J.; Ullschmied, J.; Dudzak, R.; Krousky, E.; Cykhardt, J.; Prokupek, J.; Pfeifer, M.; Rosinski, M.; Krasa, J.; Brabcova, K.; De Napoli, M.; Lastovicka, T.; Margarone, D.

    2017-06-01

    A solid hydrogen thin ribbon, produced by the cryogenic system ELISE (Experiments on Laser Interaction with Solid hydrogEn) target delivery system, was experimentally used at the PALS kJ-laser facility to generate intense proton beams with energies in the MeV range. This sophisticated target system operating at cryogenic temperature (~ 10 K) continuously producing a 62 μm thick target was combined with a 600 J sub-nanosecond laser pulse to generate a collimated proton stream. The accelerated proton beams were fully characterized by a number of diagnostics. High conversion efficiency of laser to energetic protons is of great interest for future potential applications in non-conventional proton therapy and fast ignition for inertial confinement fusion.

  11. Study of the radioactivity induced in air by a 15-MeV proton beam.

    PubMed

    Braccini, S; Ereditato, A; Nesteruk, K P; Scampoli, P; Zihlmann, K

    2015-02-01

    Radioactivity induced by a 15-MeV proton beam extracted into air was studied at the beam transport line of the 18-MeV cyclotron at the Bern University Hospital (Inselspital). The produced radioactivity was calculated and measured by means of proportional counters located at the main exhaust of the laboratory. These devices were designed for precise assessment of air contamination for radiation protection purposes. The main produced isotopes were (11)C, (13)N and (14)O. Both measurements and calculations correspond to two different irradiation conditions. In the former, protons were allowed to travel for their full range in air. In the latter, they were stopped at the distance of 1.5 m by a beam dump. Radioactivity was measured continuously in the exhausted air starting from 2 min after the end of irradiation. For this reason, the short-lived (14)O isotope gave a negligible contribution to the measured activity. Good agreement was found between the measurements and the calculations within the estimated uncertainties. Currents in the range of 120-370 nA were extracted in air for 10-30 s producing activities of 9-22 MBq of (11)C and (13)N. The total activities for (11)C and (13)N per beam current and irradiation time for the former and the latter irradiation conditions were measured to be (3.60 ± 0.48) × 10(-3) MBq (nA s)(-1) and (2.89 ± 0.37) × 10(-3) MBq (nA s)(-1), respectively.

  12. Heavy-atom neutral beams for tandem-mirror end plugs

    SciTech Connect

    Post, D.E.; Grisham, L.R.; Santarius, J.F.; Emmert, G.A.

    1981-05-01

    The advantages of neutral beams with Z greater than or equal to 3 formed from negative ions, accelerated to 0.5 to 1.0 MeV/amu, and neutralized with high efficiency, are investigated for use in tandem mirror reactor end plugs. These beams can produce Q's of 20 to 30, and thus can replace the currently proposed 200 to 500 keV neutral proton beams presently planned for tandem mirror reactors. Thus, these Z greater than or equal to 3 neutral beams increase the potential attractiveness of tandem mirror reactors by offering a substitute for difficult high energy neutral hydrogen end plug beams.

  13. Self-organized microstructures induced by MeV ion beam on silicon surface

    NASA Astrophysics Data System (ADS)

    Ahmad, Muthanna

    2017-02-01

    Micro patterning of self organized structure on silicon surface is induced by ion implantation of energetic (MeV) copper ions. This work reports for the first time the ability of using energetic ions for producing highly ordered ripples and dots of micro sizes. The experiments are realized at the Tandem ion beam accelerator (3 MV) at the IBA laboratory of the Atomic Energy Commission of Syria. Similarly to nano patterning formed by slow ions, the formation of micro patterned structures dots and ripples is observed to be depending on the angle of ion beam incidence, energy and ion fluence. The observation of such microstructures formation is limited to a range of ion energies (few MeV) at fluence higher than 1.75 × 1017 ion cm-2. The patterned surface layer is completely amorphousized by the ion implantation. Shadowing effect is observed in the formation of microripples and superstructures in the top of ripples. The superstructure develops new morphology that is not observed before. This morphology has butterfly shape with symmetry in its structure.

  14. Synthesis and characterisation of starch grafted superabsorbent via 10 MeV electron-beam irradiation.

    PubMed

    Zhang, Sufen; Wang, Wei; Wang, Haiyan; Qi, Wenyuan; Yue, Ling; Ye, Qingfu

    2014-01-30

    A starch-graft-polyacrylamide (St-g-PAM) superabsorbent crosslinked by N,N'-methyl bisacrylamide (MBA) was prepared using 10 MeV simultaneous electron beam irradiation at room temperature and subsequent alkaline hydrolysis. The effects of the irradiation dose, acryliamide-to-anhydroglucose unit (AM-to-AGU) ratio and crosslinker amount on the properties of the obtained polymers were evaluated. The structure of the graft copolymer was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Optimisation treatments were carried out and found for a total dose of 8 kGy, an AM-to-AGU ratio of 4.5 mol mol(-1) and a crosslinker-to-AM ratio of 0.4%mol mol(-1). The obtained superabsorbent polymer showed the maximum absorptions of 1,452 gg(-1) and 83 gg(-1) for distilled water and saline solution, respectively (relative to its own dry weight). The results suggest 10 MeV electron beam irradiation is more efficient than γ-ray irradiation due to its higher energy and dose rate.

  15. MeV ion beam lithography of biocompatible halogenated Parylenes using aperture masks

    NASA Astrophysics Data System (ADS)

    Whitlow, Harry J.; Norarat, Rattanaporn; Roccio, Marta; Jeanneret, Patrick; Guibert, Edouard; Bergamin, Maxime; Fiorucci, Gianni; Homsy, Alexandra; Laux, Edith; Keppner, Herbert; Senn, Pascal

    2015-07-01

    Parylenes are poly(p-xylylene) polymers that are widely used as moisture barriers and in biomedicine because of their good biocompatibility. We have investigated MeV ion beam lithography using 16O+ ions for writing defined patterns in Parylene-C, which is evaluated as a coating material for the Cochlear Implant (CI) electrode array, a neuroprosthesis to treat some forms of deafness. Parylene-C and -F on silicon and glass substrates as well as 50 μm thick PTFE were irradiated to different fluences (1 ×1013 - 1 ×1016 1 MeV 16O+ ions cm-2) through aperture masks under high vacuum and a low pressure (<10-3 mbar) oxygen atmosphere. Biocompatibility of the irradiated and unirradiated surfaces was tested by cell-counting to determine the proliferation of murine spiral ganglion cells. The results reveal that an oxygen ion beam can be used to pattern Parylene-C and -F without using a liquid solvent developer in a similar manner to PTFE but with a ∼25× smaller removal rate. Biocompatibility tests showed no difference in cell adhesion between irradiated and unirradiated areas or ion fluence dependence. Coating the Parylene surface with an adhesion-promoting protein mixture had a much greater effect on cell proliferation.

  16. Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector.

    PubMed

    Mizuno, T; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Watanabe, K; Dairaku, M; Sakamoto, K; Inoue, T

    2010-02-01

    Heat load on acceleration grids by secondary particles such as electrons, neutrals, and positive ions, is a key issue for long pulse acceleration of negative ion beams. Complicated behaviors of the secondary particles in multiaperture, multigrid (MAMuG) accelerator have been analyzed using electrostatic accelerator Monte Carlo code. The analytical result is compared to experimental one obtained in a long pulse operation of a MeV accelerator, of which second acceleration grid (A2G) was removed for simplification of structure. The analytical results show that relatively high heat load on the third acceleration grid (A3G) since stripped electrons were deposited mainly on A3G. This heat load on the A3G can be suppressed by installing the A2G. Thus, capability of MAMuG accelerator is demonstrated for suppression of heat load due to secondary particles by the intermediate grids.

  17. Fast ion behavior during neutral beam injection in ATF

    SciTech Connect

    Wade, M.R.; Thomas, C.E.; Colchin, R.J.; Rome, J.A.; England, A.C.; Fowler, R.H.; Aceto, S.C.

    1993-09-01

    In stellarators, single-particle confinement properties can be more complex than in their tokamak counterparts. Fast-ion behavior in tokamaks has been well characterized through an abundance of measurements on various devices and in general has been shown to be consistent with classical slowing-down theory, although anomalous ion behavior has been observed during intense beam injection in ISX-B, during fishbone instabilities in PDX, and in experiments on TFR. In contrast, fast ion behavior in stellarators is not as wel established experimentally with the primary experiments to date focusing o near-perpendicular or perpendicular neutral beam injection (NBI) on the Wendelstein 7-A stellarator (91 and Heliotron-E. This paper addresses fast-ion confinement properties in a large-aspect-ratio, moderate-shear stellarator, the Advanced Toroidal Facility, during tangential NBI. The primary data used in this study are the experimentally measured energy spectra of charge-exchange neutrals escaping from the plasma, using a two-dimensional scanning neutral particle analyzer. This diagnostic method is well established, having been used on several devices since the early 1970`s. Various aspects of fast-ion behavior are investigated by comparing these data with computed theoretical spectra based on energeticion distributions derived from the fastion Fokker-Planck equation. Ion orbits are studied by computer orbit following, by the computation of J* surfaces, and by Monte Carlo calculations.

  18. Development of neutral beams for fusion plasma heating

    SciTech Connect

    Haselton, H.H.; Pyle, R.V.

    1980-01-01

    A state-of-the-art account of neutral beam technology at the LBL/LLNL and ORNL facilities is given with emphasis on positive-ion-based systems. The advances made in the last few years are elaborated and problem areas are identified. The ORNL program has successfully completed the neutral injection systems for PLT, ISX-B, and most recently, PDX and the ISX-B upgrade. All of these are high current (60 to 100 A), medium energy (40 to 50 keV) systems. This program is also engaged in the development of a reactor-grade advanced positive ion system (150 to 200 kV/100 A/5 to 10 s) and a multimegawatt, long pulse (30 s) heating system for ISX-C. In a joint program, LBL and LLNL are developing and testing neutral beam injection systems based on the acceleration of positive ions for application in the 80- to 160-keV range on MFTF-B, D-III, TFTR/TFM, ETF, MNS, etc. A conceptual design of a 160-keV injection system for the German ZEPHYR project is in progress at LBL/LLNL and independently at ORNL. The laboratories are also engaged in the development of negative-ion-based systems for future applications at higher energies.

  19. Beam Phase Space of an Intense Ion Beam in a Neutralizing Plasma

    NASA Astrophysics Data System (ADS)

    Seidl, Peter A.; Bazouin, Guillaume; Beneytout, Alice; Lidia, Steven M.; Vay, Jean-Luc; Grote, David P.

    2011-10-01

    The Neutralized Drift Compression Experiment (NDCX-I) generates high intensity ion beams to explore warm dense matter physics. Transverse final focusing is accomplished with an 8-Tesla, 10-cm long pulsed solenoid magnet combined with a background neutralizing plasma to effectively cancel the space charge field of the ion beam. We report on phase space measurements of the beam before the neutralization channel and of the focused ion beam at the target plane. These are compared to WARP particle-in-cell simulations of the ion beam propagation through the focusing system and neutralizing plasma. Due to the orientation of the plasma sources with respect to the focusing magnet, the plasma distribution within the final focusing lens is strongly affected by the magnetic field, an effect which can influence the peak intensity at the target and which is included in the model of the experiment. Work performed under auspices of U.S. DoE by LLNL, LBNL under Contracts DE-AC52-07NA27344, DE-AC02-05CH1123.

  20. A space-charge-neutralizing plasma for beam drift compression

    NASA Astrophysics Data System (ADS)

    Roy, P. K.; Seidl, P. A.; Anders, A.; Bieniosek, F. M.; Coleman, J. E.; Gilson, E. P.; Greenway, W.; Grote, D. P.; Jung, J. Y.; Leitner, M.; Lidia, S. M.; Logan, B. G.; Sefkow, A. B.; Waldron, W. L.; Welch, D. R.

    2009-07-01

    Simultaneous radial focusing and longitudinal compression of intense ion beams are being studied to heat matter to the warm dense matter, or strongly coupled plasma regime. Higher compression ratios can be achieved if the beam compression takes place in a plasma-filled drift region in which the space-charge forces of the ion beam are neutralized. Recently, a system of four cathodic arc plasma sources has been fabricated and the axial plasma density has been measured. A movable plasma probe array has been developed to measure the radial and axial plasma distribution inside and outside of a ˜10-cm-long final focus solenoid (FFS). Measured data show that the plasma forms a thin column of diameter ˜5 mm along the solenoid axis when the FFS is powered with an 8 T field. Measured plasma density of ⩾1×10 13 cm -3 meets the challenge of np/ Znb>1, where np and nb are the plasma and ion beam density, respectively, and Z is the mean ion charge state of the beam ions.

  1. BEAM TRANSPORT AND STORAGE WITH COLD NEUTRAL ATOMS AND MOLECULES

    SciTech Connect

    Walstrom, Peter L.

    2012-05-15

    A large class of cold neutral atoms and molecules is subject to magnetic field-gradient forces. In the presence of a field, hyperfine atomic states are split into several Zeeman levels. The slopes of these curves vs. field are the effective magnetic moments. By means of optical pumping in a field, Zeeman states of neutral lithium atoms and CaH molecules with effective magnetic moments of nearly {+-} one Bohr magneton can be selected. Particles in Zeeman states for which the energy increases with field are repelled by increasing fields; particles in states for which the energy decreases with field are attracted to increasing fields. For stable magnetic confinement, field-repelled states are required. Neutral-particle velocities in the present study are on the order of tens to hundreds of m/s and the magnetic fields needed for transport and injection are on the order of in the range of 0.01-1T. Many of the general concepts of charged-particle beam transport carry over into neutral particle spin-force optics, but with important differences. In general, the role of bending dipoles in charged particle optics is played by quadrupoles in neutral particle optics; the role of quadrupoles is played by sextupoles. The neutralparticle analog of charge-exchange injection into storage rings is the use of lasers to flip the state of particles from field-seeking to field-repelled. Preliminary tracking results for two neutral atom/molecule storage ring configurations are presented. It was found that orbit instabilities limit the confinment time in a racetrack-shaped ring with discrete magnetic elements with drift spaces between them; stable behavior was observed in a toroidal ring with a continuous sextupole field. An alternative concept using a linear sextupole or octupole channel with solenoids on the ends is presently being considered.

  2. Predictive Simulations of ITER Including Neutral Beam Driven Toroidal Rotation

    SciTech Connect

    Halpern, Federico D.; Kritz, Arnold H.; Bateman, Glenn; Pankin, Alexei Y.; Budny, Robert V.; McCune, Douglas C.

    2008-06-16

    Predictive simulations of ITER [R. Aymar et al., Plasma Phys. Control. Fusion 44, 519 2002] discharges are carried out for the 15 MA high confinement mode (H-mode) scenario using PTRANSP, the predictive version of the TRANSP code. The thermal and toroidal momentum transport equations are evolved using turbulent and neoclassical transport models. A predictive model is used to compute the temperature and width of the H-mode pedestal. The ITER simulations are carried out for neutral beam injection (NBI) heated plasmas, for ion cyclotron resonant frequency (ICRF) heated plasmas, and for plasmas heated with a mix of NBI and ICRF. It is shown that neutral beam injection drives toroidal rotation that improves the confinement and fusion power production in ITER. The scaling of fusion power with respect to the input power and to the pedestal temperature is studied. It is observed that, in simulations carried out using the momentum transport diffusivity computed using the GLF23 model [R.Waltz et al., Phys. Plasmas 4, 2482 (1997)], the fusion power increases with increasing injected beam power and central rotation frequency. It is found that the ITER target fusion power of 500 MW is produced with 20 MW of NBI power when the pedesta temperature is 3.5 keV. 2008 American Institute of Physics. [DOI: 10.1063/1.2931037

  3. Experimental studies to test simple flexural neutralizers fitted to beams

    NASA Astrophysics Data System (ADS)

    Clark, P.; White, R. G.

    1994-10-01

    The control of vibration in one-dimensional structures is of considerable interest in practical engineering. With the majority of industrial machinery installations, it is this type of structure, for example, beams, pipework vibrating at low frequencies and other mechanical linkages, which forms one of the main vibration paths that bypass isolator systems. It is of interest to consider discontinuities that may be incorporated into these types of structure since they significantly affect the vibration characteristics of the complete installation. One such discontinuity that may be employed in vibration control is the vibration neutralizer. Previous work in this area of research has developed theoretical models of the neutralizer performance as a vibration control technique with particular reference to the effect of incorporating alternative mounting methods. In this work, complementary experimental studies are presented with a view to validating those theoretical studies previously undertaken.

  4. Control System of Neutral Beam Injection on HT-7

    NASA Astrophysics Data System (ADS)

    Wang, Yongjun; Hu, Chundong; Liu, Zhimin; Liu, Sheng; Song, Shihua; Yang, Daoye

    2005-06-01

    Neutral Beam Injection control system (NBICS) is constructed to measure the plasma current, Magnet current, vacuum pressure, cryopump temperature, control water cooling, filament voltage, and power supply, etc. The NBICS, consisting mainly of a Programmable Logic Controller (PLC) subsystem, data acquisition and processing subsystem and cryopump and vacuum pressure monitoring subsystem, has successfully been used on a NBI device. In this article, the design of NBICS on HT-7 is discussed and each subsystem is described in particular. In addition, some experimental results are reported which are very important data for further research related to the HT-7 tokamak.

  5. Neutral beam heating of a RFP plasma in MST

    SciTech Connect

    Waksman, J.; Anderson, J. K.; Nornberg, M. D.; Parke, E.; Reusch, J. A.; Liu, D.; Fiksel, G.; Davydenko, V. I.; Ivanov, A. A.; Stupishin, N.; Deichuli, P. P.; Sakakita, H.

    2012-12-15

    Electron temperature is observed to rise due to neutral beam injection (NBI) in the Madison Symmetric Torus (MST). Heating is observed to be 100 {+-} 50 eV in the core of 200 kA plasmas. This is the first definitive measurement of auxiliary heating of a reversed-field pinch (RFP). This heating is consistent with a 1D classical model which was developed. This 1D model calculates the evolving thermal conductivity and ohmic power input profiles during enhanced confinement, and can calculate NBI deposition and classical fast ion diffusion and slowing. The predicted temperature change is consistent with measured beam heating both during and after enhanced confinement, which is consistent with previous observations that fast ions are well confined and behave roughly classically in the RFP.

  6. Development of rf plasma generators for neutral beams

    SciTech Connect

    Vella, M.C.; Ehlers, K.W.; Kippenhan, D.; Pincosy, P.A.; Pyle, R.V.; DiVergilio, W.F.; Fosnight, V.V.

    1984-10-01

    The development of low frequency (1-2 MHz) rf plasma generators for high power neutral beam applications is summarized. Immersed couplers from one to three turns were used. Acceptable plasma profiles, less than or equal to 15% max/min, were obtained in a variety of field-free magnetic bucket and magnetic filter-bucket sources, with 10 x 10 cm or 10 x 40 cm extraction areas. Hydrogen beam properties were measured with a 7 x 10 cm accelerator operated at 80 kV. Atomic fraction and power efficiency were at least as high as with arc plasmas in similar chambers. The potential advantages of an rf plasma source are: ease of operation; reliability; and extended service lifetime.

  7. Si etching with reactive neutral beams of very low energy

    SciTech Connect

    Hara, Yasuhiro; Hamagaki, Manabu; Mise, Takaya; Iwata, Naotaka; Hara, Tamio

    2014-12-14

    A Si etching process has been investigated with reactive neutral beams (NBs) extracted using a low acceleration voltage of less than 100 V from CF{sub 4} and Ar mixed plasmas. The etched Si profile shows that the etching process is predominantly anisotropic. The reactive NB has a constant Si etching rate in the acceleration voltage range from 20 V to 80 V. It is considered that low-energy NBs can trigger Si etching because F radicals adsorb onto the Si surface and weaken Si–Si bonds. The etching rate per unit beam flux is 33 times higher than that with Ar NB. These results show that the low-energy reactive NB is useful for damage-free high speed Si etching.

  8. Neutral atom beam technique enhances bioactivity of PEEK

    NASA Astrophysics Data System (ADS)

    Khoury, Joseph; Kirkpatrick, Sean R.; Maxwell, Melissa; Cherian, Raymond E.; Kirkpatrick, Allen; Svrluga, Richard C.

    2013-07-01

    Polyetheretherketone (PEEK) is currently gaining popularity in orthopedic and spinal applications but has potential drawbacks in use. PEEK is biocompatible, similar in elasticity to bone, and radiolucent; however, it has been shown to be inert and does not integrate well with bone. Recent efforts have focused on increasing the bioactivity of PEEK by modifying the surface to improve the bone-implant interface. We have employed a novel Accelerated Neutral Atom Beam technique (ANAB) to enhance the bioactivity of PEEK. ANAB employs an intense beam of cluster-like packets of accelerated unbonded neutral argon (Ar) gas atoms. These beams are created by first producing a highly energetic Gas Cluster Ion Beam (GCIB) comprised of van der Waals bonded Ar atoms, then transferring energy to the clusters so as to cause release of most of the interatomic bonds, and finally deflecting away the remaining electrically charged cluster cores of still bonded atoms. We identified that ANAB treatment of PEEK results in nanometer scale surface modifications as well as increased surface hydrophilicity. Human osteoblasts seeded onto the surface of ANAB-treated PEEK exhibited enhanced growth as compared to control PEEK as evidenced by cell proliferation assays and microscopy. This increase in bioactivity resulted in cell proliferation levels comparable to native titanium. An in vivo study using a rat calvarial critical size defect model revealed enhanced osseointegration where bone tissue formation was evident only on the ANAB treated PEEK. Taken together, these data suggest that ANAB treatment of PEEK has the potential to enhance its bioactivity, resulting in bone formation and significantly decreasing osseointegration time of orthopedic and spinal implants.

  9. Traceable charge measurement of the pulses of a 27 MeV electron beam from a linear accelerator

    NASA Astrophysics Data System (ADS)

    Schüller, A.; Illemann, J.; Renner, F.; Makowski, C.; Kapsch, R.-P.

    2017-03-01

    This work presents a detailed description of measuring devices and calibration procedures which enable the nondestructive (non-intercepting) absolute measurement of the charge of individual beam pulses (macro-pulses) from an electron linear accelerator traceable to primary standards with high accuracy, i.e. with an expanded measurement uncertainty < 0.1%. In particular, we demonstrate the readout and calibration of a Bergoz integrating current transformer which is frequently applied at many different types of accelerators as a beam intensity monitor. The current transformer signal is calibrated against the absolute charge measurement by means of a custom-made compact Faraday cup with a high degree of collection efficiency for electron beams in the energy range of 6 MeV to 50 MeV (99.2% at 27 MeV), which is well known from measurements and consistently described by Monte Carlo calculations.

  10. A Space-Charge-Neutralizing Plasma for Beam Drift Compression

    SciTech Connect

    Roy, P.K.; Seidl, P.A.; Anders, A.; Bieniosek, F.M.; Coleman, J.E.; Gilson, E.P.; Greenway, W.; Grote, D.P.; Jung, J.Y.; Leitner, M.; Lidia, S.M.; Logan, B.G.; Sefkow, A.B.; Waldron, W.L.; Welch, D.R.

    2008-08-01

    Simultaneous radial focusing and longitudinal compression of intense ion beams are being studied to heat matter to the warm dense matter, or strongly coupled plasma regime. Higher compression ratios can be achieved if the beam compression takes place in a plasma-filled drift region in which the space-charge forces of the ion beam are neutralized. Recently, a system of four cathodic arc plasma sources has been fabricated and the axial plasma density has been measured. A movable plasma probe array has been developed to measure the radial and axial plasma distribution inside and outside of a {approx} 10 cm long final focus solenoid (FFS). Measured data show that the plasma forms a thin column of diameter {approx} 5 mm along the solenoid axis when the FFS is powered with an 8T field. Measured plasma density of {ge} 1 x 10{sup 13} cm{sup -3} meets the challenge of n{sub p}/Zn{sub b} > 1, where n{sub p} and n{sub b} are the plasma and ion beam density, respectively, and Z is the mean ion charge state of the plasma ions.

  11. The Neutral Beam Test Facility and Radiation Effects Facility at Brookhaven National Laboratory

    SciTech Connect

    McKenzie-Wilson, R.B.

    1990-01-01

    As part of the Strategic Defense Initiative (SDI) Brookhaven National Laboratory (BNL) has constructed a Neutral Beam Test Facility (NBTF) and a Radiation Effects Facility (REF). These two facilities use the surplus capacity of the 200-MeV Linac injector for the Alternating Gradient Synchrotron (AGS). The REF can be used to simulate radiation damage effects in space from both natural and man made radiation sources. The H{sup {minus}} beam energy, current and dimensions can be varied over a wide range leading to a broad field of application. The NBTF has been designed to carry out high precision experiments and contains an absolute reference target system for the on-line calibration of measurements carried out in the experimental hall. The H{sup {minus}} beam energy, current and dimensions can also be varied over a wide range but with tradeoffs depending on the required accuracy. Both facilities are fully operational and will be described together with details of the associated experimental programs.

  12. Several atomic-physics issues connected with the use of neutral beams in fusion experiments

    SciTech Connect

    Post, D.E.; Grisham, L.R.; Fonck, R.J.

    1982-08-01

    Energetic neutral beams are used for heating and diagnostics in present magnetic fusion experiments. They are also being considered for use in future large experiments. Atomic physics issues are important for both the production of the neutral beams and the interaction of the beams and the plasma. Interest in neutral beams based on negative hydrogen ions is growing, largely based on advances in producing high current ion sources. An extension of the negative ion approach has been the suggestion to use negative ions of Z > 1 elements, such as carbon and oxygen, to form high power neutral beams for plasma heating.

  13. Electrostatic steering and beamlet aiming in large neutral beam injectors

    SciTech Connect

    Veltri, P. Chitarin, G.; Marcuzzi, D.; Sartori, E.; Serianni, G.; Sonato, P.; Cavenago, M.

    2015-04-08

    Neutral beam injection is the main method for plasma heating in magnetic confinement fusion devices. In high energy injector (E>100 keV/amu), neutrals are obtained with reasonable efficiency by conversion of negative ions (H- or D-) via electron detachment reactions. In the case of ITER injectors, which shall operate at 1 MeV, a total ion current of ∼ 40 A is required to satisfy the heating power demand. Gridded electrodes are therefore used in the accelerator, so that 1280 negative ion beamlets are accelerated together. A carefully designed aiming system is required to control the beamlet trajectories, and to deliver their power on a focal point located several meters away from the beam source. In nowadays injectors, the aiming is typically obtained by aperture offset technique or by grid shaping. This paper discuss an alternative concept of beamlets aiming, based on an electrostatic ”steerer” to be placed at the end of the accelerator. A feasibility study of this component is also presented, and its main advantages and drawbacks with respect to other methods are discussed.

  14. Overview of the design of the ITER heating neutral beam injectors

    NASA Astrophysics Data System (ADS)

    Hemsworth, R. S.; Boilson, D.; Blatchford, P.; Dalla Palma, M.; Chitarin, G.; de Esch, H. P. L.; Geli, F.; Dremel, M.; Graceffa, J.; Marcuzzi, D.; Serianni, G.; Shah, D.; Singh, M.; Urbani, M.; Zaccaria, P.

    2017-02-01

    The heating neutral beam injectors (HNBs) of ITER are designed to deliver 16.7 MW of 1 MeV D0 or 0.87 MeV H0 to the ITER plasma for up to 3600 s. They will be the most powerful neutral beam (NB) injectors ever, delivering higher energy NBs to the plasma in a tokamak for longer than any previous systems have done. The design of the HNBs is based on the acceleration and neutralisation of negative ions as the efficiency of conversion of accelerated positive ions is so low at the required energy that a realistic design is not possible, whereas the neutralisation of H- and D- remains acceptable (≈56%). The design of a long pulse negative ion based injector is inherently more complicated than that of short pulse positive ion based injectors because: • negative ions are harder to create so that they can be extracted and accelerated from the ion source; • electrons can be co-extracted from the ion source along with the negative ions, and their acceleration must be minimised to maintain an acceptable overall accelerator efficiency; • negative ions are easily lost by collisions with the background gas in the accelerator; • electrons created in the extractor and accelerator can impinge on the extraction and acceleration grids, leading to high power loads on the grids; • positive ions are created in the accelerator by ionisation of the background gas by the accelerated negative ions and the positive ions are back-accelerated into the ion source creating a massive power load to the ion source; • electrons that are co-accelerated with the negative ions can exit the accelerator and deposit power on various downstream beamline components. The design of the ITER HNBs is further complicated because ITER is a nuclear installation which will generate very large fluxes of neutrons and gamma rays. Consequently all the injector components have to survive in that harsh environment. Additionally the beamline components and the NB cell, where the beams are housed, will be

  15. Scheme for Low Energy Beam Transport with a Non-Neutralized Section

    SciTech Connect

    Shemyakin, A.; Prost, L.

    2015-04-23

    A typical Low Energy Beam Transport (LEBT) design relies on dynamics with nearly complete beam space charge neutralization over the entire length of the LEBT. This paper argues that, for a beam with modest perveance and uniform current density distribution when generated at the source, a downstream portion of the LEBT can be un-neutralized without significant emittance growth.

  16. High speed measurements of neutral beam turn-on and impact of beam modulation on measurements of ion density

    DOE PAGES

    Grierson, Brian A.; Burrell, Keith H.; Crowley, Brendan J.; ...

    2014-10-02

    Modulation of neutral beams on tokamaks is performed routinely, enabling background rejection for active spectroscopic diagnostics, and control of injected power and torque. We find that there exists an anomalous initial transient in the beam neutrals delivered to the tokamak that is not accounted for by the accelerator voltage and power supply current. Measurements of the charge-exchange and beam photoemission on the DIII-D tokamak at high speed (200 μs) reveal that the energy of the beam neutrals is constant, but the density of beam neutrals displays dramatic variation in the first 2–3 ms following beam turn-on. Here, the impact ofmore » this beam density variation on inferred ion densities and impurity transport is presented, with suggested means to correct for the anomalous transient.« less

  17. High speed measurements of neutral beam turn-on and impact of beam modulation on measurements of ion density

    SciTech Connect

    Grierson, Brian A.; Burrell, Keith H.; Crowley, Brendan J.; Grisham, L.; Scoville, John T.

    2014-10-02

    Modulation of neutral beams on tokamaks is performed routinely, enabling background rejection for active spectroscopic diagnostics, and control of injected power and torque. We find that there exists an anomalous initial transient in the beam neutrals delivered to the tokamak that is not accounted for by the accelerator voltage and power supply current. Measurements of the charge-exchange and beam photoemission on the DIII-D tokamak at high speed (200 μs) reveal that the energy of the beam neutrals is constant, but the density of beam neutrals displays dramatic variation in the first 2–3 ms following beam turn-on. Here, the impact of this beam density variation on inferred ion densities and impurity transport is presented, with suggested means to correct for the anomalous transient.

  18. Thermal effects in high power cavities for photoneutralization of D- beams in future neutral beam injectors

    NASA Astrophysics Data System (ADS)

    Fiorucci, Donatella; Feng, Jiatai; Pichot, Mikhaël; Chaibi, Walid

    2015-04-01

    Photoneutralization may represent a key issue in the neutral beam injectors for future fusion reactors. In fact, photodetachment based neutralization combined with an energy recovery system increase the injector overall efficiency up to 60%. This is the SIPHORE injector concept in which photoneutralization is realized in a refolded cavity [1]. However, about 1 W of the several megaWatts intracavity power is absorbed by the mirrors coatings and gives rise to important thermoelastic distortions. This is expected to change the optical behavior of the mirrors and reduce the enhancement factor of the cavity. In this paper, we estimate these effects and we propose a thermal system to compensate it.

  19. Positive and negative ion beam merging system for neutral beam production

    DOEpatents

    Leung, Ka-Ngo; Reijonen, Jani

    2005-12-13

    The positive and negative ion beam merging system extracts positive and negative ions of the same species and of the same energy from two separate ion sources. The positive and negative ions from both sources pass through a bending magnetic field region between the pole faces of an electromagnet. Since the positive and negative ions come from mirror image positions on opposite sides of a beam axis, and the positive and negative ions are identical, the trajectories will be symmetrical and the positive and negative ion beams will merge into a single neutral beam as they leave the pole face of the electromagnet. The ion sources are preferably multicusp plasma ion sources. The ion sources may include a multi-aperture extraction system for increasing ion current from the sources.

  20. Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

    NASA Technical Reports Server (NTRS)

    Rutherford, J. A.; Vroom, D. A.

    1978-01-01

    In order to form metal vapors for neutral beam studies, an electron-beam heater and a power supply have been designed. The source, which measures about 30 x 50 x 70 mm, consists of a filament, accelerating plate (defined by pole pieces), and a supported target. The electrons from the filament are focused by the field penetration through a 2 mm slit in the high-voltage cage. They are then accelerated to about 5 kV to a ground plate. The electrons then follow a path in the magnetic field and strike the sample to be heated on its front surface. The assembly is attached to a water-cooled base plate. The electron beam source has produced beams of Ta and C particles with densities of about 10 to the 8th power/cu cm.

  1. Radiation parameters of 6 to 20 MeV scanning electron beams from the Saturne linear accelerator.

    PubMed

    Pfalzner, P M; Clarke, H C

    1982-01-01

    Depth doses of the scanning electron beams from the Saturne Therac-20 linear accelerator at nominal energies of 6,9,13,17, and 20 MeV were measured in polystyrene using a thin window parallel plate ionization chamber. Central axis depth dose curves are derived and are analyzed according to the method of Brahme and Svensson. For each of the five electron energies, values are obtained for the most probable energy at the absorber surface Ep,0, the practical range Rp, the 50% range R50, the therapeutic range R85, the electron dose gradients, total collision energy losses, and other radiation parameters, and these are compared to corresponding values for electron beams from a 22 MeV medical microtron and a 20 MeV betatron.

  2. Comparison of experimental data and 3D simulations of ion beam neutralization from the neutralized transport experiment

    SciTech Connect

    Thoma, C.; Welch, D.R.; Yu, S.S.; Henestroza, E.; Roy, P.K.; Eylon, S.; Gilson, E.P.

    2004-09-22

    The Neutralized Transport Experiment (NTX) at Lawrence Berkeley National Laboratory has been designed to study the final focus and neutralization of high perveance ion beams for applications in heavy ion fusion (HIF) and high energy density physics (HEDP) experiments. Pre-formed plasmas in the last meter before the target of the scaled experiment provide a source of electrons which neutralize the ion current and prevent the space-charge induced spreading of the beam spot. NTX physics issues are discussed and experimental data is analyzed and compared with 3D particle-in-cell simulations. Along with detailed target images, 4D phase-space data of the NTX at the entrance of the neutralization region has been acquired. This data is used to provide a more accurate beam distribution with which to initialize the simulation. Previous treatments have used various idealized beam distributions which lack the detailed features of the experimental ion beam images. Simulation results are compared with NTX experimental measurements for 250 keV K{sup +} ion beams with dimensionless perveance of 1-7 x 10{sup -4}. In both simulation and experiment, the deduced beam charge neutralization is close to the predicted maximum value.

  3. Feedback control of multimode magnetohydrodynamic instabilities via neutral beams

    SciTech Connect

    Sen, A.K.

    1998-08-01

    In most scenarios of confinement degradation due to MHD (magnetohydrodynamic) fluctuations in both tokamaks and reversed field pinches several MHD modes are involved. This is the motivation for the development of a multimode feedback scheme in the present paper, in contrast to the past work. The scheme is based on modal (state) feedback, where each mode is unscrambled out of the sensor signal, which is a superposition of all mode information and then individually acted upon by a unique gain and phase. Finally, all these individually processed mode signals are electronically summed and impressed on the accelerator grid of a neutral beam as a single control signal. It is shown that this process can lead to the stabilization of all unstable modes without destabilization of any stable modes, in contrast to previous feedback experiments. {copyright} {ital 1998 American Institute of Physics.}

  4. Confinement studies during neutral beam injection in PLT

    SciTech Connect

    Goldston, R.; Davis, S.; Eubank, H.

    1980-12-01

    Neutral beam injection experiments on PLT have provided definitive information on ion energy confinement in highly collisionless plasmas. We find that ion thermal conduction is consistent, within a factor of approx. 3, with neoclassical theory, and that anomalous thermal convection of ion energy is a factor of 2-3 less than would be calculated from the INTOR D/sub e/ with a convection loss term of the form 5/2nkTv/sub r/. From our experiments with a shunted TF coil we have found that a single shallow ripple well of 2.5% has a neglible effect on ion energy confinement, even at the lowest collisionality obtainable on PLT. Scrutiny of the analytic theories of ripple induced transport motivated by these experiments, suggests that more theoretical (and perhaps numerical) work is needed in this area.

  5. Neutral beam injection in a D 3He FRC reactor

    NASA Astrophysics Data System (ADS)

    Ferrari, Hugo; Farengo, Ricardo

    2007-06-01

    The use of neutral beam injection (NBI) to sustain a fraction of the plasma current in a field reversed configuration (FRC) reactor operating with the D-3He reaction is studied. A Monte Carlo code already used to study NBI in medium size FRCs is employed (Lifschitz A F, Farengo R and Arista N R 2002 Nucl. Fusion 42 863, Lifschitz A F, Farengo R and Arista N R 2002 Plasma Phys. Control. Fusion 44 1979, Lifschitz A F, Farengo R and Hoffman A L 2004 Nucl. Fusion 44 1015) and the plasma parameters are similar to those proposed in the ARTEMIS (Momota H, Ishida A, Kohzaki Y, Miley G, Ohi S, Ohnishi M, Sato K, Steinhauer L, Tomita Y and Tuszewki M 1992 Fusion Technol. 21 2307) conceptual reactor design. A simple analysis shows that the driven current cannot reach the values quoted in the ARTEMIS project and a procedure to search for plasma parameters that result in higher efficiencies is presented.

  6. Compact, maintainable 80-KeV neutral beam module

    DOEpatents

    Fink, Joel H.; Molvik, Arthur W.

    1980-01-01

    A compact, maintainable 80-keV arc chamber, extractor module for a neutral beam system immersed in a vacuum of <10.sup.-2 Torr, incorporating a nested 60-keV gradient shield located midway between the high voltage ion source and surrounding grounded frame. The shield reduces breakdown or arcing path length without increasing the voltage gradient, tends to keep electric fields normal to conducting surfaces rather than skewed and reduces the peak electric field around irregularities on the 80-keV electrodes. The arc chamber or ion source is mounted separately from the extractor or ion accelerator to reduce misalignment of the accelerator and to permit separate maintenance to be performed on these systems. The separate mounting of the ion source provides for maintaining same without removing the ion accelerator.

  7. Simulation study of neutron production in thick beryllium targets by 35 MeV and 50.5 MeV proton beams

    NASA Astrophysics Data System (ADS)

    Shin, Jae Won; Park, Tae-Sun

    2017-09-01

    A data-driven nuclear model dedicated to an accurate description of neutron productions in beryllium targets bombarded by proton beams is developed as a custom development that can be used as an add-on to GEANT4 code. The developed model, G4Data(Endf7.1), takes as inputs the total and differential cross section data of ENDF/B-VII.1 for not only the charge-exchange 9Be(p,n)9B reaction which produces discrete neutrons but also the nuclear reactions relevant for the production of continuum neutrons such as 9Be(p,pn)8Be and 9Be(p,n α) 5Li . In our benchmarking simulations for two experiments with 35 MeV and 50.5 MeV proton beams impinged on 1.16 and 1.05 cm thick beryllium targets, respectively, we find that the G4Data(Endf7.1) model can reproduce both the total amounts and the spectral shapes of the measured neutron yield data in a satisfactory manner, while all the considered hadronic models of GEANT4 cannot.

  8. Laboratory studies of the charge neutralization of a rocket payload during electron beam emission

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Whalen, B. A.; Harris, F. R.; Mcnamara, A. G.; Konradi, A.

    1980-01-01

    The charge neutralization of an electrically-isolated rocket payload emitting an energetic electron beam has been studied in experiments in the large vacuum chamber at Johnson Space Center. The introduction of an RF-discharge-produced ambient plasma density (10,000 to 50,000 per cu cm) reduces the payload potential to 200 V for low current (1 and 10 ma) beams. The ignition of the beam-plasma discharge provides an efficient neutralization process for higher current beams.

  9. Observation of Beam Driven Modes during Neutral Beam Heating on the National Spherical Torus Experiment

    SciTech Connect

    E.D. Fredrickson; N. Gorelenkov; C.Z. Cheng; R. Bell; D. Darrow; D. Johnson; S. Kaye; B. LeBlanc; J. Menard; S. Kubota; W. Peebles

    2001-10-03

    With the first injection of neutral beams on the National Spherical Torus Experiment (NSTX), a broad and complicated spectrum of coherent modes was seen between approximately 0.4 MHz and 2.5 MHz [where f(subscript ''ci'')] for deuterium is approximately 2.2 MHz. The modes have been observed with high bandwidth magnetic pick-up coils and with a reflectometer. The parametric scaling of the mode frequency with density and magnetic field is consistent with Alfvenic modes (linear in B, inversely with the square root of density). These modes have been identified as magnetosonic waves or compressional Alfven eigenmodes (CAE) excited by a cyclotron resonance with the neutral-beam ions. Modes have also been observed in the frequency range 50-150 kHz with toroidal mode numbers n = 1-5. These lower frequency modes are thought to be related to the TAE [Toroidal Alfven Eigenmode] seen commonly in tokamaks and driven by energetic fast ion populations resulting from ICRF [ion cyclotron range of frequency] and NBI [neutral-beam injection] heating. There is no clear indication of enhanced fast ion losses associated with the modes.

  10. Heat-exchanger concepts for neutral-beam calorimeters

    SciTech Connect

    Thompson, C.C.; Polk, D.H.; McFarlin, D.J.; Stone, R.

    1981-10-05

    Advanced cooling concepts that permit the design of water cooled heat exchangers for use as calorimeters and beam dumps for advanced neutral beam injection systems were evaluated. Water cooling techniques ranging from pool boiling to high pressure, high velocity swirl flow were considered. Preliminary performance tests were carried out with copper, inconel and molybdenum tubes ranging in size from 0.19 to 0.50 in. diameter. Coolant flow configurations included (1) smooth tube/straight flow, (2) smooth tube with swirl flow created by tangential injection of the coolant, and (3) axial flow in internally finned tubes. Additionally, the effect of tube L/D was evaluated. A CO/sub 2/ laser was employed to irradiate a sector of the tube exterior wall; the laser power was incrementally increased until burnout (as evidenced by a coolant leak) occurred. Absorbed heat fluxes were calculated by dividing the measured coolant heat load by the area of the burn spot on the tube surface. Two six element thermopiles were used to accurately determine the coolant temperature rise. A maximum burnout heat flux near 14 kW/cm/sup 2/ was obtained for the molybdenum tube swirl flow configuration.

  11. The Timing System of the Neutral Beam Injector on EAST

    NASA Astrophysics Data System (ADS)

    Sheng, Peng; Hu, Chundong; Zhao, Yuanzhe; Cui, Qinglong; Zhang, Xiaodan; Wu, Deyun; Zhang, Rui; Lin, Yulian

    2015-05-01

    In order to synchronize the elements of the EAST Neutral Beam Injector (NBI) spatially located in several places, a distributed Timing System (TS) is developed in this paper. The timing system provides a clock reference for synchronization and an interlock protection of the EAST NBI system. It sends timing signals to field devices, controls the pulse widths of the timing sequences, and provides a sampling clock for the Data Acquisition System (DAS). The timing system also generates analog waveforms to control power supplies and gas supplies according to the operator's configuration. The timing system is developed on a PXI (PCI eXtensions for Instrumentation) platform consisting of a LabVIEW workstation and a timing control terminal. The timing control terminal consists of a timing node and several control interface crates. Two timing nodes are configured in one beam line. Each node is responsible for the timing sequence, analog generation and feedback control for one ion source. The architecture and implementation of the timing system are presented in this paper.

  12. DIII-D Neutral Beam control system operator interface

    SciTech Connect

    Harris, J.J.; Campbell, G.L.

    1993-10-01

    A centralized graphical user interface has been added to the DIII-D Neutral Beam (NB) control systems for status monitoring and remote control applications. This user interface provides for automatic data acquisition, alarm detection and supervisory control of the four NB programmable logic controllers (PLC) as well as the Mode Control PLC. These PLCs are used for interlocking, control and status of the NB vacuum pumping, gas delivery, and water cooling systems as well as beam mode status and control. The system allows for both a friendly user interface as well as a safe and convenient method of communicating with remote hardware that formerly required interns to access. In the future, to enable high level of control of PLC subsystems, complete procedures is written and executed at the touch of a screen control panel button. The system consists of an IBM compatible 486 computer running the FIX DMACS{trademark} for Windows{trademark} data acquisition and control interface software, a Texas Instruments/Siemens communication card and Phoenix Digital optical communications modules. Communication is achieved via the TIWAY (Texas Instruments protocol link utilizing both fiber optic communications and a copper local area network (LAN). Hardware and software capabilities will be reviewed. Data and alarm reporting, extended monitoring and control capabilities will also be discussed.

  13. Initial neutral beam injection results on the UCLA Electric Tokamak.

    NASA Astrophysics Data System (ADS)

    Taylor, R. J.; Carter, T. C.; Gauvreau, J.-L.; Gourdain, P.-A.; Grossman, A.; Lafonteese, D. J.; Pace, D. C.; Schmitz, L. W.; White, A. E.; Yates, T. F.

    2004-11-01

    The most important innovation needed in tokamaks is to achieve non-inductive current profiles with zero loop voltage(K. C. Shaing et al., Phys. Rev. Lett.79), 3679 (1997). We have added a low velocity (< 10 kV) neutral beam on ET for fuelling, toroidal momentum input and diagnostic purposes. Simulations with TSC(S.C. Jardin, et al, J. Comp. Phys 66), 481 (1986) indicate that steady state can be achieved at beta normal of 2 in about 3 seconds of time evolution. The resulting theoretical current profiles are stable to ballooning and other modes at these beta levels. Initial injection test indicate that good beam operations have been obtained at 100 kW levels resulting in ion heating and rotation but not but not yet in current drive from bootstrap. Both co and counter injection tests will be made. The diagnostic capability on ET has been expanded recently for profile measurements. Detailed predictions will be presented based on the TSC code and compared to achieved results.

  14. Heat-exchanger concepts for neutral-beam calorimeters

    NASA Astrophysics Data System (ADS)

    Thompson, C. C.; Polk, D. H.; McFarlin, D. J.; Stone, R.

    1981-10-01

    Advanced cooling concepts that permit the design of water cooled heat exchangers for use as calorimeters and beam dumps for advanced neutral beam injection systems were evaluated. Water cooling techniques ranging from pool boiling to high pressure, high velocity swirl flow were considered. Preliminary performance tests were carried out with copper, inconel and molybdenum tubes ranging in size from 0.19 to 0.50 in. diameter. Coolant flow configurations included: (1) smooth tube/straight flow; (2) smooth tube with swirl flow created by tangential injection of the coolant; and (3) axial flow in internally finned tubes. Additionally, the effect of tube L/D was evaluated. A CO2 laser was employed to irradiate a sector of the tube exterior wall; the laser power was incrementally increased until burnout occurred. Absorbed heat fluxes were calculated by dividing the measured coolant heat load by the area of the burn spot on the tube surface. Two six element thermopiles were used to accurately determine the coolant temperature rise. A maximum burnout heat flux near 14 kW/sq cm was obtained for the molybdenum tube swirl flow configuration.

  15. Observation of Electron Cloud Stabilized 1 MeV Beam-Beam d+d Reactons in Self-Colliding Orbits and Feasibility of Electric Isotope Breeder

    NASA Astrophysics Data System (ADS)

    Maglich, Bogdan; Druey, Christian; Iyengar, P. K.; Srinivasan, Mahadeva

    2012-03-01

    D-D Self-Collider ^1,2 is only system in which beam-beam nuclear reactions demonstrated MeV energies. 1.45 MeV DC beam of D2^+ was injected into center of a weak-focusing magnetic field (Ni Ti) B=3.12 Tesla, and dissociated into 2 d^+ stored in Self-Colliding Orbits^3. Energy confinement time T = 23 s (vacuum limited p=10-9 torr), stabilized by driven electron oscillations^4. A simulation^5 shows that 1 DD neutron is produced at an energy cost of 5.36 MeV/n i.e. 140 MWh/g= 8,360/g vs. 160,000/g from beam - target. Simultaneously produced He^3 and T are not only free, but bring 45 fold gain. 5 d's of 0.75 MeV generate 1He^3 +1T +1p+ 1n at cost 5.36 MeV. Hence, it will produce 2 He^3 nuclei (1 He-3, 1 T) plus energy gain of 161 MeV. This will be reduced by the energy gain thus reducing cost to 4.5 from 5.6 MeV. Assumed ion density 5x10 ^14 was achieved in plasmas. Beam injection 100 mA. 1. PRL 54, 796 (1985) NIM A 271 p,.1-167; 2. AIP CP 311, 292 (93); 3. PRL 70, 1818 (93); 4.Part. Acc.1, (70); 5. ``50 Years with Fission'' Symp.Nat. Ac Sci., p. 761 (89)

  16. The plasma focus as a source of collimated beams of negative ion clusters and of neutral deuterium atoms

    NASA Astrophysics Data System (ADS)

    Nardi, V.; Powell, C.

    1984-03-01

    We report the space anisotropy and brightness B4 (i.e., the momentum normalized density in four dimensional transverse phase space) of a high-intensity pulsed source of neutral-atom and negative-ion-cluster beams with energy/atom E≳0.2 Mev, ion clusters with m/Z (a.u.) ≳200. The source is formed in an 0.5 MA plasma focus-PF-discharge. The energy spectrum of different particle species is obtained from a 12.2 kG magnetic analyzer, energy filters and time resolved detectors. Collimated particle beams are ejected within a <6° cone along the discharge axis inside a ≳3 mm diameter plasma channel (neutral atoms, ion clusters, impurity heavy ions at 0°, electron beams, clusters and negatively-charged ion clumps at 180°). Pulsed kA currents of ions (and neutral fluence of comparable intensity at 180°) are detected in the 6° cone at 0° with B4˜107 (mA/cm2rad2) for particle energies E≳200 KeV. In the 180° direction the soruce ejects multiple pulses of electron and ion beams in alternating sequency (typical pulse duration ˜10 ns) with a net negative charge which provide charge neutralization for ion and ion cluster beams. The source which can operate—in principle—at a high repetition rate has a scaling law in which the particle-intensity increases without a detectable increase of the angular dispersion.

  17. Testing a prototype BGO calorimeter with 100-800 MeV positron beams

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Fujimura, H.; Grigoriev, D. N.; Hashimoto, R.; Kaida, S.; Kitazawa, R.; Kuznetsov, G. N.; Nakamura, A.; Shimizu, H.; Suzuki, K.; Takahashi, S.; Tsuchikawa, Y.; Vasiliev, Ya. V.; Yamazaki, H.

    2016-11-01

    An electromagnetic calorimeter, BGOegg, composed of 1320 BGO crystals, has been constructed at the Research Center for Electron Photon Science, Tohoku University to study the structure of hadrons in detail using photo-induced reactions. The design of the new electromagnetic calorimeter and the basic characteristics of the manufactured BGO crystals are described. A performance test has been conducted for the prototype, which consists of 25 crystals arranged in a 5×5 matrix, using positron beams at energies ranging from 100 to 800 MeV. The obtained energy resolution is (σE / E) 2 =(0.63 %) 2 +(1.15 % ± 0.04 %) 2 /(E / GeV) +(0.42 % ± 0.03 %) 2 /(E / GeV) 2 at room temperature. The energy resolution corresponds to 1.38 % ± 0.05 % for 1-GeV positrons. The position resolution is found to be σr / mm =(3.07 ± 0.03)(E / GeV) - 0.202 ± 0.008 which corresponds to an angular resolution of approximately 1 ° for 1-GeV positrons.

  18. Coherent transition and diffraction radiation from a bunched 6.1 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Naumenko, G. A.; Aleinik, A. N.; Aryshev, A. S.; Kalinin, B. N.; Potylitsyn, A. P.; Saruev, G. A.; Sharafutdinov, A. F.

    2005-01-01

    The theory of transition radiation (TR) from an ideally conducting infinite target is well known. During the last several years the theory of diffraction radiation (DR) from simple geometry targets has further been developed. In a few experiments coherent TR and coherent DR were used to measure the electron bunch length. However, experimental investigations of coherent TR (or DR) look rather poor for finite size targets. The experimental results of investigation of coherent backward transition radiation (CBTR) and coherent backward diffraction radiation (CBDR) are presented. The intensity of CBTR and CBDR from a finite conducting target for different impact-parameters depending on the target inclination angle θ ( θ-scan) has been investigated using the 6 MeV electron beam of the Tomsk microtron. The model allowing to calculate both TR and DR characteristics for any impact-parameter h (the shortest distance between particle trajectory and target edge) was developed and tested by comparison with experimental results. The calculations were performed for the real experimental conditions. For γλ ≫ h ( γ - Lorentz-factor, λ - TR (DR) wavelength) and large detector bandwidth {γ(λmax-λmin)}/{h}>1 the measured TR angular distribution shows a single maximum only (like DR one) in contrast to a lobe-shaped OTR distribution.

  19. Electron-temperature requirements for neutralized inertial-confinement-fusion light-ion beams

    SciTech Connect

    Lemons, D.S.

    1981-01-01

    Because of their large self-space-charge fields, light ion beam drivers of energy and power sufficient to achieve inertial confinement fusion (ICF) cannot be focused on a small fuel pellet unless neutralized. Even if initially neutralized with comoving electrons, these beams will not stay neutralized and focus during propagation through a vacuum chamber unless the initial thermal energy of the neutralizing electrons is sufficiently small. In this paper we discuss the effects which contribute to the effective initial temperature of the neutralizing electrons, including compressional shock heating. We also employ a simple heuristic model to construct envelope equations which govern axial as well as radial beam compression and use them to predict the largest initial electron temperature consistent with the required beam compression. This temperature for typical light ion beam systems is about ten eV - a temperature which may be possible to achieve.

  20. Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector

    SciTech Connect

    Barbisan, M. Zaniol, B.; Pasqualotto, R.

    2014-11-15

    A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H{sup −}/D{sup −} ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the H{sub α}/D{sub α} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled H{sub α} spectra in the case of MITICA experiment.

  1. Neutral beam dose and sputtering characteristics in an ion implantation system

    NASA Technical Reports Server (NTRS)

    Roberts, A. S., Jr.; Ash, R. L.; Berger, M. H.

    1973-01-01

    A technique and instrument design for calorimetric detection of the neutral atom content of a 60 keV argon ion beam. A beam sampling method is used to measure local heat flux to a small platinum wire at steady state; integration of power density profiles leads to a determination of equivalent neutral beam current. The fast neutral production occurs as a result of charge transfer processes in the region of the beam system between analyzing magnet and beam stop where the pressure remains less than .00001 torr. A description of the neutral beam detector is given in section along with a presentation of results. An elementary analysis of sputter material transport from target to substrate was performed; the analysis relates to semiconductor sputtering.

  2. Effects of MHD instabilities on neutral beam current drive

    SciTech Connect

    Podestà, M.; Gorelenkova, M.; Darrow, D. S.; Fredrickson, E. D.; Gerhardt, S. P.; White, R. B.

    2015-04-17

    One of the primary tools foreseen for heating, current drive (CD) and q-profile control in future fusion reactors such as ITER and a Fusion Nuclear Science Facility is the neutral beam injection (NBI). However, fast ions from NBI may also provide the drive for energetic particle-driven instabilities (e.g. Alfvénic modes (AEs)), which in turn redistribute fast ions in both space and energy, thus hampering the control capabilities and overall efficiency of NB-driven current. Based on experiments on the NSTX tokamak (M. Ono et al 2000 Nucl. Fusion 40 557), the effects of AEs and other low-frequency magneto-hydrodynamic instabilities on NB-CD efficiency are investigated. When looking at the new fast ion transport model, which accounts for particle transport in phase space as required for resonant AE perturbations, is utilized to obtain consistent simulations of NB-CD through the tokamak transport code TRANSP. It is found that instabilities do indeed reduce the NB-driven current density over most of the plasma radius by up to ~50%. Moreover, the details of the current profile evolution are sensitive to the specific model used to mimic the interaction between NB ions and instabilities. Finally, implications for fast ion transport modeling in integrated tokamak simulations are briefly discussed.

  3. Toroidal midplane neutral beam armor and plasma limiter

    DOEpatents

    Kugel, H.W.; Hand, S.W. Jr.; Ksayian, H.

    1985-05-31

    This invention contemplates an armor shield/plasma limiter positioned upon the inner wall of a toroidal vacuum chamber within which is magnetically confined an energetic plasma in a tokamak nuclear fusion reactor. The armor shield/plasma limiter is thus of a general semi-toroidal shape and is comprised of a plurality of adjacent graphite plates positioned immediately adjacent to each other so as to form a continuous ring upon and around the toroidal chamber's inner wall and the reactor's midplane coil. Each plate has a generally semi-circular outer circumference and a recessed inner portion and is comprised of upper and lower half sections positioned immediately adjacent to one another along the midplane of the plate. With the upper and lower half sections thus joined, a channel or duct is provided within the midplane of the plate in which a magnetic flux loop is positioned. The magnetic flux loop is thus positioned immediately adjacent to the fusing toroidal plasma and serves as a diagnostic sensor with the armor shield/plasma limiter minimizing the amount of power from the energetic plasma as well as from the neutral particle beams heating the plasma incident upon the flux loop.

  4. Effects of MHD instabilities on neutral beam current drive

    DOE PAGES

    Podestà, M.; Gorelenkova, M.; Darrow, D. S.; ...

    2015-04-17

    One of the primary tools foreseen for heating, current drive (CD) and q-profile control in future fusion reactors such as ITER and a Fusion Nuclear Science Facility is the neutral beam injection (NBI). However, fast ions from NBI may also provide the drive for energetic particle-driven instabilities (e.g. Alfvénic modes (AEs)), which in turn redistribute fast ions in both space and energy, thus hampering the control capabilities and overall efficiency of NB-driven current. Based on experiments on the NSTX tokamak (M. Ono et al 2000 Nucl. Fusion 40 557), the effects of AEs and other low-frequency magneto-hydrodynamic instabilities on NB-CDmore » efficiency are investigated. When looking at the new fast ion transport model, which accounts for particle transport in phase space as required for resonant AE perturbations, is utilized to obtain consistent simulations of NB-CD through the tokamak transport code TRANSP. It is found that instabilities do indeed reduce the NB-driven current density over most of the plasma radius by up to ~50%. Moreover, the details of the current profile evolution are sensitive to the specific model used to mimic the interaction between NB ions and instabilities. Finally, implications for fast ion transport modeling in integrated tokamak simulations are briefly discussed.« less

  5. The potential role of Neutral Beam Injection in EU DEMO

    NASA Astrophysics Data System (ADS)

    Vincenzi, Pietro; Artaud, Jean-Francois; Bolzonella, Tommaso; Giruzzi, Gerardo

    2016-10-01

    EU DEMO studies for pulsed (DEMO1) and steady-state (DEMO2) concepts are currently in the pre-conceptual phase. Present DEMO1 design is based on ITER baseline H-mode scenario, while DEMO2 is based on advanced scenarios with moderate reversed q profile sustained by non-inductive currents. One of the possible flattop heating power systems currently considered is Neutral Beam Injection (NBI). In this work the role of NBI in DEMO1 and DEMO2 is investigated by means of integrated simulations of DEMO scenarios using METIS fast tokamak modelling tool. Limitations, requirements and benefits of the use of a NBI system are discussed. For DEMO1 pulsed concept, the role of NBI is mainly central plasma heating for scenario stability (high fusion power H-mode). As a by-product of the tangential injection, NBI is capable of current drive, which is favorable in order to extend the discharge duration. Regarding a steady-state DEMO2 concept, in addition to plasma heating, NBI becomes a direct actuator for the advanced scenario by driving a considerable part of the plasma current. This requires more than 100MW with off-axis injection. The effect of an increase of the injection energy on the driven current density profile is also presented for DEMO2.

  6. Sparking protection for MFTF-B neutral beam power supplies

    SciTech Connect

    Cummings, D.B.

    1983-11-30

    This paper describes the upgrade of MFTF-B Neutral Beam Power Supplies for sparking protection. High performance ion sources spark repeatedly so ion source power supplies must be insensitive to sparking. The hot deck houses the series tetrode, arc and filament supplies, and controls. Hot deck shielding has been upgraded and a continuous shield around the arc, filament, gradient grid, and control cables now extends from the hot deck, through the core snubber, to the source. The shield carries accelerating current and connects only to the source. Shielded source cables go through an outer duct which now connects to a ground plane under the hot deck. This hybrid transmission line is a low inductance path for sparks discharging the stray capacitance of the hot deck and isolation transformers, reducing coupling to building steel. Parallel dc current return cables inside the duct lower inductance to reduce inductive turn-off transients. MOVs to ground further limit surges in the remote power supply return. Single point grounding is at the source. No control or rectifier components have been damaged nor are there any known malfunctions due to sparking up to 80 kV output.

  7. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik

    2014-02-01

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E < 12.47% for 99% particles). The whole linac comprises mainly E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 1011 n/cm2/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  8. Neutral-beam system based on BNL negative-hydrogen-ion sources

    SciTech Connect

    Prelec, K.

    1982-01-01

    Parameters of the conceptual design of the BNL neutral beam system were determined as follows: beam energy, 200 keV; negative ion current, 10A; neutral beam power, 1 MW; pulse length, multisecond to steady state. The completed system study, supported by successful ion source operation at the required level, will serve to evaluate and compare different approaches in the design of a negative ion based system and, eventually, lead to the design and construction of an operational system.

  9. Effects of neutral gas releases on electron beam injection from electrically tethered spacecraft

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.

    1990-01-01

    The presence of high neutral densities at low altitudes and/or during thruster firings is known to modify the spacecraft potential during active electron beam injection. Two-dimensional (three velocity) particle simulations are used to investigate the ionization processes including the neutral density required, the modification of the spacecraft potential, beam profile and spatial distribution of the return current into the spacecraft. Three processes are identified: (1) beam-induced ionization, (2) vehicle-induced ionization, and (3) beam plasma discharge. Only in the first two cases does the beam propagate away with little distortion.

  10. Conceptual design of the beam source for the DEMO Neutral Beam Injectors

    NASA Astrophysics Data System (ADS)

    Sonato, P.; Agostinetti, P.; Fantz, U.; Franke, T.; Furno, I.; Simonin, A.; Tran, M. Q.

    2016-12-01

    DEMO (DEMOnstration Fusion Power Plant) is a proposed nuclear fusion power plant that is intended to follow the ITER experimental reactor. The main goal of DEMO will be to demonstrate the possibility to produce electric energy from the fusion reaction. The injection of high energy neutral beams is one of the main tools to heat the plasma up to fusion conditions. A conceptual design of the Neutral Beam Injector (NBI) for the DEMO fusion reactor, is currently being developed by Consorzio RFX in collaboration with other European research institutes. High efficiency and low recirculating power, which are fundamental requirements for the success of DEMO, have been taken into special consideration for the DEMO NBI. Moreover, particular attention has been paid to the issues related to reliability, availability, maintainability and inspectability. A conceptual design of the beam source for the DEMO NBI is here presented featuring 20 sub-sources (two adjacent columns of 10 sub-sources each), following a modular design concept, with each sub-source featuring its radio frequency driver, capable of increasing the reliability and availability of the DEMO NBI. Copper grids with increasing size of the apertures have been adopted in the accelerator, with three main layouts of the apertures (circular apertures, slotted apertures and frame-like apertures for each sub-source). This design, permitting to significantly decrease the stripping losses in the accelerator without spoiling the beam optics, has been investigated with a self-consistent model able to study at the same time the magnetic field, the electrostatic field and the trajectory of the negative ions. Moreover, the status on the R&D carried out in Europe on the ion sources is presented.

  11. MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Jeynes, J. C. G.; Merchant, M. J.; Kirkby, K.; Kirkby, N.; Thopan, P.; Yu, L. D.

    2013-07-01

    As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.

  12. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    SciTech Connect

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; Murphy, C.

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracy of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.

  13. Consideration of neutral beam prompt loss in the design of a tokamak helicon antenna

    DOE PAGES

    Pace, D. C.; Van Zeeland, M. A.; Fishler, B.; ...

    2016-08-02

    Neutral beam prompt losses (injected neutrals that ionize such that their first poloidal transit intersects with the wall) can put appreciable power on the outer wall of tokamaks, and this power may damage the wall or other internal components. These prompt losses are simulated including a protruding helicon antenna installation in the DIII-D tokamak and it is determined that 160 kW of power will impact the antenna during the injection of a particular neutral beam. Protective graphite tiles are designed in response to this modeling and the wall shape of the installed antenna is precisely measured to improve the accuracymore » of these calculations. Initial experiments con rm that the antenna component temperature increases according to the amount of neutral beam energy injected into the plasma. Incorporating neutral beam prompt loss considerations into the design of this in-vessel component serves to ensure that adequate protection or cooling is provided.« less

  14. Solenoid assembly with beam focusing and radiation shielding functions for the 9/6 MeV dual energy linac

    NASA Astrophysics Data System (ADS)

    Cha, Sungsu; Kim, Yujong; Ju, Jinsik; Joo, Youngwoo; Lee, Byeong-No; Lee, Soo Min; Kim, Jae Hyun; Buaphad, Pikad; Lee, Byung Cheol; Cha, Hyungki; Ha, Jang Ho; Park, Hyung Dal; Song, Ki Beak; Lee, Seung Hyun; Kim, Heesoo

    2016-09-01

    The Korea Atomic Energy Research Institute (KAERI) has been developing a Container Inspection System (CIS) by using a dual-energy (9/6 MeV) S-band (= 2856 MHz) electron linear accelerator. The key components of the CIS are the electron linear accelerator (including an electron gun, an accelerating structure, an RF power source, cooling chillers, vacuum pumps, magnet power supplies, and two solenoid magnets with beam focusing and shielding functions), a tungsten target for X-ray generation, an X-ray collimator, a detector array, and a container moving system. Generally, in accelerators, beam focusing is mainly done by solenoids operating in the region of a few MeV to keep the shape of transverse beam symmetrically round so as to reduce the loss of electrons, which increases the beam current and the beam power. In addition, a specially-designed component is needed to protect against the radiation due to the lost electrons. In this paper, we describe the design, fabrication, and optimization of two specially- designed solenoids with focusing and radiation shielding functions for a dual-energy S-band electron linear accelerator for a CIS.

  15. Enhancing the effect of 4MeV electron beam using gold nanoparticles in breast cancer cells.

    PubMed

    Mehrnia, Somayeh Sadat; Hashemi, Bijan; Mowla, Seyed Javad; Arbabi, Azim

    2017-03-01

    Gold nanoparticles (GNPs) have been applied as radiosensitizer in radiotherapy. Limited reports have shown that GNPs may be effective as a dose enhancer agent for electron radiation therapy. Some Monte Carlo Simulation studies have shown that selecting suitable size of GNPs and electron energies are critical for effective dose enhancement. The aim of this study was to assess possible radiosensitization effect of GNPs on cancer cell treated with 4MeV electron beams. Approximately 10nm GNPs were synthesized and characterized by electron microscope and dynamic light scattering. MCF-7 and MDA-MB-231 breast cancer cells were used and their viability was measured by MTT assay. Radiosensitization effect of GNPs under 4MeV electron beams was measured by clonogenic assay. The result showed a concentration dependent uptake of GNPs without reducing cell viability at concentrations ≤50mg/L. Incubation of cancer cells with GNPs caused a significant decrease in their viability following exposure to electron beams as well as a decrease in their survival fraction when compared to control. The sensitizer enhancement ratio (SER) by electron beams in MCF-7 cells was 1.43 and 1.40 in presence of 25 and 50mg/L GNPs, respectively. For MDA-MB-231 cells, it was 1.62 in presence of 25mg/L GNPs. Our data demonstrated the significant dose enhancement of the GNPs in combination with 4MeV electron beams that could be applicable for the treatment of superficial tumors and intra operative radiation therapy. Copyright © 2017. Published by Elsevier Ltd.

  16. Beyond ITER: neutral beams for a demonstration fusion reactor (DEMO) (invited).

    PubMed

    McAdams, R

    2014-02-01

    In the development of magnetically confined fusion as an economically sustainable power source, International Tokamak Experimental Reactor (ITER) is currently under construction. Beyond ITER is the demonstration fusion reactor (DEMO) programme in which the physics and engineering aspects of a future fusion power plant will be demonstrated. DEMO will produce net electrical power. The DEMO programme will be outlined and the role of neutral beams for heating and current drive will be described. In particular, the importance of the efficiency of neutral beam systems in terms of injected neutral beam power compared to wallplug power will be discussed. Options for improving this efficiency including advanced neutralisers and energy recovery are discussed.

  17. Ta2O5-based redox memory formed by neutral beam oxidation

    NASA Astrophysics Data System (ADS)

    Ohno, Takeo; Samukawa, Seiji

    2016-06-01

    A room temperature neutral beam oxidation process using a tantalum (Ta) metal film was used to obtain a high quality Ta oxide (Ta2O5) film. After irradiation of a Ta metal film with a neutral oxygen beam, a nanometer-thick Ta2O5 film with a film density of 7.5 g/cm3 was obtained. We also confirmed that the fabricated Cu/Ta2O5/Pt redox memory structure shows a bipolar resistive switching characteristic. This result demonstrates the great potential of neutral beam metal oxidation for the development of redox-based memory devices.

  18. Beyond ITER: Neutral beams for a demonstration fusion reactor (DEMO) (invited)

    SciTech Connect

    McAdams, R.

    2014-02-15

    In the development of magnetically confined fusion as an economically sustainable power source, International Tokamak Experimental Reactor (ITER) is currently under construction. Beyond ITER is the demonstration fusion reactor (DEMO) programme in which the physics and engineering aspects of a future fusion power plant will be demonstrated. DEMO will produce net electrical power. The DEMO programme will be outlined and the role of neutral beams for heating and current drive will be described. In particular, the importance of the efficiency of neutral beam systems in terms of injected neutral beam power compared to wallplug power will be discussed. Options for improving this efficiency including advanced neutralisers and energy recovery are discussed.

  19. A new deflection technique applied to an existing scheme of electrostatic accelerator for high energy neutral beam injection in fusion reactor devices.

    PubMed

    Pilan, N; Antoni, V; De Lorenzi, A; Chitarin, G; Veltri, P; Sartori, E

    2016-02-01

    A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor. In order to solve these two issues, a magnetic deflector is proposed to screen the BS from direct exposure to radiation and neutrons so that the voltage insulation between the electrostatic accelerator and the grounded vessel can be enhanced by using compressed SF6 instead of vacuum so that the negative ions can be accelerated at energies higher than 1 MeV. By solving the beam transport with different magnetic deflector properties, an optimum scheme has been found which is shown to be effective to guarantee both the steering effect and the beam aiming.

  20. A new deflection technique applied to an existing scheme of electrostatic accelerator for high energy neutral beam injection in fusion reactor devices

    SciTech Connect

    Pilan, N. Antoni, V.; De Lorenzi, A.; Chitarin, G.; Veltri, P.; Sartori, E.

    2016-02-15

    A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor. In order to solve these two issues, a magnetic deflector is proposed to screen the BS from direct exposure to radiation and neutrons so that the voltage insulation between the electrostatic accelerator and the grounded vessel can be enhanced by using compressed SF{sub 6} instead of vacuum so that the negative ions can be accelerated at energies higher than 1 MeV. By solving the beam transport with different magnetic deflector properties, an optimum scheme has been found which is shown to be effective to guarantee both the steering effect and the beam aiming.

  1. Optimization of a constrained linear monochromator design for neutral atom beams.

    PubMed

    Kaltenbacher, Thomas

    2016-04-01

    A focused ground state, neutral atom beam, exploiting its de Broglie wavelength by means of atom optics, is used for neutral atom microscopy imaging. Employing Fresnel zone plates as a lens for these beams is a well established microscopy technique. To date, even for favorable beam source conditions a minimal focus spot size of slightly below 1μm was reached. This limitation is essentially given by the intrinsic spectral purity of the beam in combination with the chromatic aberration of the diffraction based zone plate. Therefore, it is important to enhance the monochromaticity of the beam, enabling a higher spatial resolution, preferably below 100nm. We propose to increase the monochromaticity of a neutral atom beam by means of a so-called linear monochromator set-up - a Fresnel zone plate in combination with a pinhole aperture - in order to gain more than one order of magnitude in spatial resolution. This configuration is known in X-ray microscopy and has proven to be useful, but has not been applied to neutral atom beams. The main result of this work is optimal design parameters based on models for this linear monochromator set-up followed by a second zone plate for focusing. The optimization was performed for minimizing the focal spot size and maximizing the centre line intensity at the detector position for an atom beam simultaneously. The results presented in this work are for, but not limited to, a neutral helium atom beam.

  2. Doppler-shift spectra of Hα lines from negative-ion-based neutral beams for large helical device neutral beam injection

    NASA Astrophysics Data System (ADS)

    Oka, Y.; Ikeda, K.; Takeiri, Y.; Tsumori, K.; Kaneko, O.; Nagaoka, K.; Osakabe, M.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Grisham, L.; Umeda, N.; Honda, A.; Ikeda, Y.; Yamamoto, T.

    2006-03-01

    The velocity spectra of the negative-ion-(H-) based neutral beams are studied in high-performance large-area ion sources during injection into large helical device fusion plasmas. We are conducting systematic observations in standard neutral beam injection to correlate beam spectra with source operating conditions. Almost all of the transmitted beam power was at full acceleration energy (˜170keV). The small stripping beam component which was produced in the extraction gap was evaluated to be about 9%-22% by amplitude of the measured spectra for the sources in beam lines 1 and 2. H- production uniformity from the spectrum profile was 86%-90% for three sources. For the longest pulse injection during 74 and 128 s, a full energy component tended to decrease with time, while the accelerator gap stripping tail tended to increase slightly with time, which is attributed to beam-induced outgassing in the accelerator. A higher conductance multislot ground grid accelerator appeared to show little growth in the accelerator gap beam stripping during long pulses compared to the conventional multiaperture ground grid. The beam uniformity appeared to vary in part with the Cs uniformity on the plasma grid.

  3. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    NASA Astrophysics Data System (ADS)

    Wu, Bin; Hao, Baolong; White, Roscoe; Wang, Jinfang; Zang, Qing; Han, Xiaofeng; Hu, Chundong

    2017-02-01

    Neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  4. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    DOE PAGES

    Wu, Bin; Hao, Baolong; White, Roscoe; ...

    2016-12-09

    Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  5. Calculation of prompt loss and toroidal field ripple loss under neutral beam injection on EAST

    SciTech Connect

    Wu, Bin; Hao, Baolong; White, Roscoe; Wang, Jinfang; Zang, Qing; Han, Xiaofeng; Hu, Chundong

    2016-12-09

    Here, neutral beam injection is a major auxiliary heating method in the EAST experimental campaign. This paper gives detailed calculations of beam loss with different plasma equilibria using the guiding center code ORBIT and NUBEAM/TRANSP. Increasing plasma current can dramatically lower the beam ion prompt loss and ripple loss. Countercurrent beam injection gives a much larger prompt loss fraction than co-injection, and ripple-induced collisionless stochastic diffusion is the dominant loss channel.

  6. Production of α-particle emitting ²¹¹At using 45 MeV α-beam.

    PubMed

    Kim, Gyehong; Chun, Kwonsoo; Park, Sung Ho; Kim, Byungil

    2014-06-07

    Among the α-particle emitting radionuclides, (211)At is considered to be a promising radionuclide for targeted cancer therapy due to its decay properties. The range of alpha particles produced by the decay of (211)At are less than 70 µm in water with a linear energy transfer between 100 and 130 keV µm(-1), which are about the maximum relative biological effectiveness for heavy ions. It is important to note that at the present time, only a few of cyclotrons routinely produce (211)At. The direct production method is based on the nuclear reactions (209)Bi(α,2n)(211)At. Production of the radionuclide (211)At was carried out using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). To ensure high beam current, the α-beam was extracted with an initial energy of 45 MeV, which was degraded to obtain the appropriate α-beam energy. The calculations of beam energy degradation were performed utilizing the MCNPX. Alumina-baked targets were prepared by heating the bismuth metal powder onto a circular cavity in a furnace. When using an E(α, av) of 29.17 MeV, the very small contribution of (210)At confirms the right choice of the irradiation energy to obtain a pure production of (211)At isotope.

  7. Comparison of measured electron density rise and calculated neutral beam particle deposition in the TFTR tokamak

    SciTech Connect

    Park, H.; Budny, R.; McCune, D.; Taylor, G.; Zarnstorff, M.C. . Plasma Physics Lab.); Barnes, C.W. )

    1991-12-01

    The initial rate of rise of the central electron density during {approximately}100 keV deuterium neutral beam injection is found to agree well with calculations of the beam deposition rate. The best agreement is with beam deposition calculations using older tabulations of the atomic cross-sections; the effects of using new tabulations or including multi-step ionization processes appear to approximately cancel. The neutral-beam deposition profile is a strong function of both the magnitude and the shape of the target plasma density. Peaked heating profiles can be achieved at high target densities only from peaked target density profiles. 15 refs., 4 figs.

  8. Dynamics of neutralized electrons and the focusability of intenseion beams in HIF accelerating structures

    SciTech Connect

    Lifschitz, A.F.; Maynard, G.; Vay, J.-V.

    2005-01-18

    In most of the proposals for HIF reactors, beams propagate ballistically through the containment chamber. To get the required final radius ({approx} 3 mm), the charge of the beam must be neutralized to some extent. Several neutralization schemes are possible, as co-injection of negative-ions beams, inclusion of external sources of electrons, or it can be provided by electrons coming from ionization of the background gas. In this work, we study the role of the electron dynamic on the neutralization and final radius of the beam. This is done by performing fully-electromagnetic PIC simulations of the beam ballistic transport using the BPIC code[1]. In agreement with previous works we found that the evolution of an isolated beam is well described as a bidimensional adiabatic compression, and the beam neutralization degree and final radius can be estimated from the initial electron transversal temperature. When a background gas is present the evolution differs significantly from an adiabatic compression. Even for low gas densities, the continuous electrons flow coming from gas ionization limits efficiently the compressional heating, thus reducing the final radius. Aspects of beam neutralization by background gas ionization are discussed.

  9. Formation of fast neutral beams and their using for selective etching

    NASA Astrophysics Data System (ADS)

    Maishev, Yu. P.; Shevchuk, S. L.; Kudrya, V. P.

    2014-12-01

    Design and main characteristics of high performance fast neutral beam sources based on the ion sources with a cold cathode and a closed drift of electrons in crossed electrical and magnetic fields are described. The output beam is of practically 100% neutrality and has a low level of divergence (<5º) which provides long distance transportation of neutral beams. Etching results for Si, SiO2, W, NbN, TiN, and TiC with using the working gases Ar, CF4, C3F8, and SF6 are given. Preliminary results for the build-in charge decreasing effect for the Si/SiO2 interface under a neutral beam treatment are presented.

  10. Dosimetric evaluation of multi-sided irradiation on HDPE pipes under 2 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

    2014-03-01

    The use of electron beam technology has enabled the production of heat resistant pipe for hot water circulation. One of the difficulties in the irradiation of pipe products is the uneven penetration of electrons. Quality of the radiation process depends on radiation dose and homogeneity of the dose distribution, which becomes a major concern when treatments of circular objects like pipes are performed. One method to achieve uniformity in the absorbed dose in the product is to use multi-sided irradiation. The paper discusses the importance of dosimetry mapping in industrial electron beam radiation processing and outlines the challenges in delivering a uniform dose to cylindrical objects. In this study, HDPE pipe of 5 mm thickness of homogeneous material (40 mm outer diameter and 30 mm inner diameter) has been chosen for multi-sided irradiation under 2 MeV scanned electron beam from the ILU-6 accelerator.

  11. Measurement of activation of helium gas by 238U beam irradiation at about 11 A MeV

    NASA Astrophysics Data System (ADS)

    Akashio, A.; Tanaka, K.; Imao, H.; Uwamino, Y.

    2017-09-01

    A new helium-gas stripper system has been applied at the 11 A MeV uranium beam of the Radioactive Isotope Beam Factory of the RIKEN accelerator facility. Although the gas stripper is important for the heavy-ion accelerator facility, the residual radiation that is generated is a serious problem for maintenance work. The residual dose was evaluated by using three-layered activation samples of aluminium and bismuth. The γ-rays from produced radionuclides with in-flight fission of the 238U beam and from the material of the chamber activated by neutrons were observed by using a Ge detector and compared with the values calculated by using the Monte-Carlo simulation code PHITS.

  12. Commissioning of a compact laser-based proton beam line for high intensity bunches around 10Â MeV

    NASA Astrophysics Data System (ADS)

    Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Kroll, F.; Blažević, A.; Bagnoud, V.; Roth, M.

    2014-03-01

    We report on the first results of experiments with a new laser-based proton beam line at the GSI accelerator facility in Darmstadt. It delivers high current bunches at proton energies around 9.6 MeV, containing more than 109 particles in less than 10 ns and with tunable energy spread down to 2.7% (ΔE/E0 at FWHM). A target normal sheath acceleration stage serves as a proton source and a pulsed solenoid provides for beam collimation and energy selection. Finally a synchronous radio frequency (rf) field is applied via a rf cavity for energy compression at a synchronous phase of -90 deg. The proton bunch is characterized at the end of the very compact beam line, only 3 m behind the laser matter interaction point, which defines the particle source.

  13. Assessment of the plasma start-up in Wendelstein 7-X with neutral beam injection

    NASA Astrophysics Data System (ADS)

    Gradic, D.; Dinklage, A.; Brakel, R.; McNeely, P.; Osakabe, M.; Rust, N.; Wolf, R.; the W7-X Team; the LHD Experimental Group

    2015-03-01

    Plasma start-up by neutral beam injection was investigated for stellarators. A zero-dimensional collisional model was extended to evaluate the temporal evolution of the plasma start-up in a confining toroidal magnetic field. Inclusion of different beam energy components indicated a substantial effect due to the energy dependence of beam-gas collisions. Additional collision processes and particle equations were considered to simulate the plasma start-up in helium-hydrogen mixtures. The isotope effect between operation with hydrogen and deuterium beams was also investigated. As a major objective the conditions necessary for a plasma start-up with neutral beams in W7-X have been examined. The assessed beam configuration in W7-X was found not to allow plasma start-up by neutral beam injection alone. The model has been validated for experimental data from W7-AS and Large Helical Device. Quantitative predictions of this study show that the ratio of the beam-plasma interaction length and the plasma volume is an essential quantity for the successful plasma start-up with neutral beams.

  14. The design of multi-megawatt actively cooled beam dumps for the Neutral-Beam Engineering Test Facility

    NASA Astrophysics Data System (ADS)

    Paterson, J. A.; Koehler, G.; Wells, R. P.

    1981-10-01

    To test neutral beam sources up to 170 keV, 65 Amps, with 30 second beam on times, actively cooled beam dumps for both the neutral and ionized particles are required. The dumps should be able to dissipate a wide range of power density profiles by utilizing a standard modular panel design which is incorporated into a moveable support structure. The thermal hydraulic design of the panels permit the dissipation of 2 kW/sq cm anywhere on the panel surface. The water requirements of the dumps are optimized by restricting the flow to panel sections where the heat flux falls short of the design value. The mechanical design of the beam-dump structures is described along with tests performed on two different panel designs. The dissipation capabilities of the panels were tested at the critical regions to verify their use in the beam dump assemblies.

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

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

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

  16. Nonlinear Charge and Current Neutralization of an Ion Beam Pulse in a Pre-formed Plasma

    SciTech Connect

    Igor D. Kaganovich; Gennady Shvets; Edward Startsev; Ronald C. Davidson

    2001-01-30

    The propagation of a high-current finite-length ion beam in a cold pre-formed plasma is investigated. The outcome of the calculation is the quantitative prediction of the degree of charge and current neutralization of the ion beam pulse by the background plasma. The electric magnetic fields generated by the ion beam are studied analytically for the nonlinear case where the plasma density is comparable in size with the beam density. Particle-in-cell simulations and fluid calculations of current and charge neutralization have been performed for parameters relevant to heavy ion fusion assuming long, dense beams with el >> V(subscript b)/omega(subscript b), where V(subscript b) is the beam velocity and omega subscript b is the electron plasma frequency evaluated with the ion beam density. An important conclusion is that for long, nonrelativistic ion beams, charge neutralization is, for all practical purposes, complete even for very tenuous background plasmas. As a result, the self-magnetic force dominates the electric force and the beam ions are always pinched during beam propagation in a background plasma.

  17. Ion beam induced charge collection (IBICC) from integrated circuit test structures using a 10 MeV carbon microbeam

    SciTech Connect

    Guo, B. N.; El Bouanani, M.; Duggan, J. L.; McDaniel, F. D.; Renfrow, S. N.; Doyle, B. L.; Walsh, D. S.; Aton, T. J.

    1999-06-10

    As feature sizes of Integrated Circuits (ICs) continue to shrink, the sensitivity of these devices, particularly SRAMs and DRAMs, to natural radiation is increasing. In this paper, the Ion Beam Induced Charge Collection (IBICC) technique is utilized to simulate neutron-induced Si recoil effects in ICs. The IBICC measurements, conducted at the Sandia National Laboratories, employed a 10 MeV carbon microbeam with 1{mu}m diameter spot to scan test structures on specifically designed ICs. With the aid of IC layout information, an analysis of the charge collection efficiency from different test areas is presented.

  18. Towards tabletop production of intense quasimonochromatic X-ray beams using small 2-20 MeV accelerators

    NASA Astrophysics Data System (ADS)

    Avakian, Robert O.; Ispirian, Karo A.

    2005-08-01

    The existing synchrotron radiation sources and the fourth generation x-ray sources, which are projected at SLAC, USA, and DESY, Germany, are very expensive. For this reason the search for the novel and cheaper sources using various types of radiation produced by 2-20 MeV electrons available at many hospitals, universities and firms in various countries is of great interest. A review of the physics, history, new theoretical and experimental results and of some applications is given with a purpose to consider the possibilities of construction of small tabletop sources of quasimonochromatic X-ray photon beams necessary for scientific, industrial, medicine and other applications.

  19. Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of cold negative ions

    DOEpatents

    Hershcovitch, A.

    1984-02-13

    A process for selectively neutralizing H/sup -/ ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H/sup -/ ions that are

  20. Benchmark testing of DIII-D neutral beam modeling with water flow calorimetry

    SciTech Connect

    Rauch, J. M.; Crowley, B. J.; Scoville, J. T.; Murphy, C. J.

    2016-06-02

    Power loading on beamline components in the DIII-D neutral beam system is measured in this paper using water flow calorimetry. The results are used to benchmark beam transport models. Finally, anomalously high heat loads in the magnet region are investigated and a speculative hypothesis as to their origin is presented.

  1. Extending DIII-D Neutral Beam Modulated Operations with a Camac Based Total on Time Interlock

    SciTech Connect

    Baggest, D.S.; Broesch, J.D.; Phillips, J.C.

    1999-11-01

    A new total-on-time interlock has increased the operational time limits of the Neutral Beam systems at DIII-D. The interlock, called the Neutral Beam On-Time-Limiter (NBOTL), is a custom built CAMAC module utilizing a Xilinx 9572 Complex Programmable Logic Device (CPLD) as its primary circuit. The Neutral Beam Injection Systems are the primary source of auxiliary heating for DIII-D plasma discharges and contain eight sources capable of delivering 20MW of power. The delivered power is typically limited to 3.5 s per source to protect beam-line components, while a DIII-D plasma discharge usually exceeds 5 s. Implemented as a hardware interlock within the neutral beam power supplies, the NBOTL limits the beam injection time. With a continuing emphasis on modulated beam injections, the NBOTL guards against command faults and allows the beam injection to be safely spread over a longer plasma discharge time. The NBOTL design is an example of incorporating modern circuit design techniques (CPLD) within an established format (CAMAC). The CPLD is the heart of the NBOTL and contains 90% of the circuitry, including a loadable, 1 MHz, 28 bit, BCD count down timer, buffers, and CAMAC communication circuitry. This paper discusses the circuit design and implementation. Of particular interest is the melding of flexible modern programmable logic devices with the CAMAC format.

  2. Surface pattern formation during MeV energy ion beam irradiation

    SciTech Connect

    Srivastava, S. K.; Nair, K. G. M.; Kannan, R. Kamala; Kamruddin, M.; Panigrahi, B. K.; Tyagi, A. K.

    2012-06-05

    Surface patterning during high energy heavy ion irradiation is a relatively recent observation. We report in this paper the results of a study on the formation of self organized ripple patterns on silica surface irradiated with MeV energy gold ions.

  3. Performance of positive ion based high power ion source of EAST neutral beam injector

    SciTech Connect

    Hu, Chundong; Xie, Yahong Xie, Yuanlai; Liu, Sheng; Xu, Yongjian; Liang, Lizhen; Jiang, Caichao; Li, Jun; Liu, Zhimin

    2016-02-15

    The positive ion based source with a hot cathode based arc chamber and a tetrode accelerator was employed for a neutral beam injector on the experimental advanced superconducting tokamak (EAST). Four ion sources were developed and each ion source has produced 4 MW @ 80 keV hydrogen beam on the test bed. 100 s long pulse operation with modulated beam has also been tested on the test bed. The accelerator was upgraded from circular shaped to diamond shaped in the latest two ion sources. In the latest campaign of EAST experiment, four ion sources injected more than 4 MW deuterium beam with beam energy of 60 keV into EAST.

  4. Neutralized ion beam modification of cellulose membranes for study of ion charge effect on ion-beam-induced DNA transfer

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.

    2012-02-01

    Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment.

  5. Observation of optical Smith-Purcell radiation at an electron beam energy of 855 MeV.

    PubMed

    Kube, G; Backe, H; Euteneuer, H; Grendel, A; Hagenbuck, F; Hartmann, H; Kaiser, K H; Lauth, W; Schöpe, H; Wagner, G; Walcher, Th; Kretzschmar, M

    2002-05-01

    Smith-Purcell radiation, generated when a beam of charged particles passes close to the surface of a diffraction grating, has been studied in the visible spectral range at wavelengths of 360 and 546 nm with the low emittance 855 MeV electron beam of the Mainz Microtron MAMI. The beam focused to a spot size of 4 microm (full width at half maximum) passed over optical diffraction gratings of echelle profiles with blaze angles of 0.8 degrees, 17.27 degrees, and 41.12 degrees and grating periods of 0.833 and 9.09 microm. Taking advantage of the specific emission characteristics of Smith-Purcell radiation a clear separation from background components, such as diffracted synchrotron radiation from upstream beam optical elements and transition radiation, was possible. The intensity scales with a modified Bessel function of the first kind as a function of the distance between electron beam and grating surface. Experimental radiation factors have been determined and compared with calculations on the basis of Van den Berg's theory [P.M. Van den Berg, J. Opt. Soc. Am. 63, 689 (1973)]. Fair agreement has been found for gratings with large blaze angles while the measurement with the shallow grating (blaze angle 0.8 degrees ) is at variance with this theory. Finally, the optimal operational parameters of a Smith-Purcell radiation source in view of already existing powerful undulator sources are discussed.

  6. Observation of optical Smith-Purcell radiation at an electron beam energy of 855 MeV

    NASA Astrophysics Data System (ADS)

    Kube, G.; Backe, H.; Euteneuer, H.; Grendel, A.; Hagenbuck, F.; Hartmann, H.; Kaiser, K. H.; Lauth, W.; Schöpe, H.; Wagner, G.; Walcher, Th.; Kretzschmar, M.

    2002-05-01

    Smith-Purcell radiation, generated when a beam of charged particles passes close to the surface of a diffraction grating, has been studied in the visible spectral range at wavelengths of 360 and 546 nm with the low emittance 855 MeV electron beam of the Mainz Microtron MAMI. The beam focused to a spot size of 4 μm (full width at half maximum) passed over optical diffraction gratings of echelle profiles with blaze angles of 0.8°, 17.27°, and 41.12° and grating periods of 0.833 and 9.09 μm. Taking advantage of the specific emission characteristics of Smith-Purcell radiation a clear separation from background components, such as diffracted synchrotron radiation from upstream beam optical elements and transition radiation, was possible. The intensity scales with a modified Bessel function of the first kind as a function of the distance between electron beam and grating surface. Experimental radiation factors have been determined and compared with calculations on the basis of Van den Berg's theory [P.M. Van den Berg, J. Opt. Soc. Am. 63, 689 (1973)]. Fair agreement has been found for gratings with large blaze angles while the measurement with the shallow grating (blaze angle 0.8°) is at variance with this theory. Finally, the optimal operational parameters of a Smith-Purcell radiation source in view of already existing powerful undulator sources are discussed.

  7. Operating characteristics of a new ion source for KSTAR neutral beam injection system.

    PubMed

    Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

    2014-02-01

    A new positive ion source for the Korea Superconducting Tokamak Advanced Research neutral beam injection (KSTAR NBI-1) system was designed, fabricated, and assembled in 2011. The characteristics of the arc discharge and beam extraction were investigated using hydrogen and helium gas to find the optimum operating parameters of the arc power, filament voltage, gas pressure, extracting voltage, accelerating voltage, and decelerating voltage at the neutral beam test stand at the Korea Atomic Energy Research Institute in 2012. Based on the optimum operating condition, the new ion source was then conditioned, and performance tests were primarily finished. The accelerator system with enlarged apertures can extract a maximum 65 A ion beam with a beam energy of 100 keV. The arc efficiency and optimum beam perveance, at which the beam divergence is at a minimum, are estimated to be 1.0 A/kW and 2.5 uP, respectively. The beam extraction tests show that the design goal of delivering a 2 MW deuterium neutral beam into the KSTAR Tokamak plasma is achievable.

  8. Evaluation of various operational and dosimetric parameters of an industrial electron beam accelerator of 2 MeV energy

    NASA Astrophysics Data System (ADS)

    Benny, P. G.; Khader, S. A.; Sarma, K. S. S.

    2014-07-01

    An industrial type 2 MeV/20 kW ILU-6 electron beam accelerator is operational in India for development of applications and technology demonstration to the Indian Industry in the field of polymer modifications (cross-linking and degradation). In order to adjust the treatment conditions and to control the good operation of the accelerator, it is necessary to study dose response as a function of various operational parameters. An experimental procedure for calibrating Cellulose Triacetate (CTA) film strip dosimeters in electron beam using total absorption graphite calorimeters is discussed and compared it with the results obtained from gamma calibration. Dosimetry data for process application, where the irradiation target is plane polymer sheet, have been obtained under various operational parameters.

  9. Surface modifications of hydrogen storage alloy by heavy ion beams with keV to MeV irradiation energies

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Tokuhira, Shinnosuke; Uchida, Hirohisa; Ohshima, Takeshi

    2015-12-01

    This study deals with the effect of surface modifications induced from keV to MeV heavy ion beams on the initial reaction rate of a hydrogen storage alloy (AB5) in electrochemical process. The rare earth based alloys like this sample alloy are widely used as a negative electrode of Ni-MH (Nickel-Metal Hydride) battery. We aimed to improve the initial reaction rate of hydrogen absorption by effective induction of defects such as vacancies, dislocations, micro-cracks or by addition of atoms into the surface region of the metal alloys. Since defective layer near the surface can easily be oxidized, the conductive oxide layer is formed on the sample surface by O+ beams irradiation, and the conductive oxide layer might cause the improvement of initial reaction rate of hydriding. This paper demonstrates an effective surface treatment of heavy ion irradiation, which induces catalytic activities of rare earth oxides in the alloy surface.

  10. Gas utilization in TFTR (Tokamak Fusion Test Reactor) neutral beam injectors

    SciTech Connect

    Kamperschroer, J.H.; Gammel, G.M.; Kugel, H.W.; Grisham, L.R.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1987-08-01

    Measurements of gas utilization in a test TFTR neutral beam injector have been performed to study the feasibility of running tritium neutral beams with existing ion sources. Gas consumption is limited by the restriction of 50,000 curies of T/sub 2/ allowed on site. It was found that the gas efficiency of the present long-pulse ion sources is higher than it was with previous short-pulse sources. Gas efficiencies were studied over the range of 35 to 55%. At the high end of this range the neutral fraction of the beam fell below that predicted by room temperature molecular gas flow. This is consistent with observations made on the JET injectors, where it has been attributed to beam heating of the neutralizer gas and a concomitant increase in conductance. It was found that a working gas isotope exchange from H/sub 2/ to D/sub 2/ could be accomplished on the first beam shot after changing the gas supply, without any intermediate preconditioning. The mechanism believed responsible for this phenomenon is heating of the plasma generator walls by the arc and a resulting thermal desorption of all previously adsorbed and implanted gas. Finally, it was observed that an ion source conditioned to 120 kV operation could produce a beam pulse after a waiting period of fourteen hours by preceding the beam extraction with several hi-pot/filament warm-up pulses, without any gas consumption. 18 refs., 7 figs., 2 tabs.

  11. Propagation of charge-neutral beams in space - Modifications when negative ions are present

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Pritchett, P. L.

    1987-01-01

    Two-dimensional (three velocity component) electrostatic simulations are used to investigate the properties of a charge-neutral beam consisting of H(+), H(-), and electrons which will be used in the Beams on Rockets (BEAR) experiment to be launched in late 1987 or early 1988. For cross-field injection and beam densities much greater than the ambient plasma density, the beam splits into two approximately charge-neutral beams: a H(+)-e(-) beam that propagates down the field lines and a H(+)-H(-) beam that propagates at nearly the initial beam velocity on time scales less than the ion gyroperiod. Because of this splitting, space-charge oscillations are induced in the H(+)-H(-) component, which lead to its breakup. At lower beam densities, particularly when the beam electron density is less than about the density of the ambient plasma, the ambient plasma response reduces the space-charge fields as the beam splits and the space-charge oscillations are suppressed.

  12. Microanalysis of materials by PIXE using focused MeV heavy ion beams

    NASA Astrophysics Data System (ADS)

    Yuji, Horino; Yoshiaki, Mokuno; Kanenaga, Fujii

    1993-04-01

    MeV heavy ion microprobes, 3 MeV C 2+, Si 2+ and Ni 2+ were applied for micro-PIXE measurements. It was found that the X-ray yields vary drastically as a function of the combination of the atomic number of incident ions and target atoms, which indicates that there is a best combination for specific element analysis. This was demonstrated by an investigation of human nail by a silicon microprobe which was compared with the case of proton. Furthermore, the minimum detectable gold weights in silicon were also estimated as a practical case and it was found that a carbon microprobe was best for measuring gold atoms in silicon.

  13. Radiation effects of 200 MeV proton beams on Nd-Fe-B magnets

    NASA Astrophysics Data System (ADS)

    Ito, Y.; Yasuda, K.; Sasase, M.; Ishigami, R.; Hatori, S.; Ohashi, K.; Tanaka, S.

    2003-08-01

    Effects of 200 MeV proton irradiation on the re-magnetized Nd-Fe-B magnet (Shin-Etsu Chemical N48) were investigated. The dose dependence of the magnetic flux loss for the re-magnetized sample agreed well with that for the unirradiated one within the experimental accuracy. The N48 magnet, demagnetized by the radiation, had perfectly its magnetic properties of its unirradiated level by means of the re-magnetization.

  14. Optimization of a photoneutron source based on 10 MeV electron beam using Geant4 Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Askri, Boubaker

    2015-10-01

    Geant4 Monte Carlo code has been used to conceive and optimize a simple and compact neutron source based on a 10 MeV electron beam impinging on a tungsten target adjoined to a beryllium target. For this purpose, a precise photonuclear reaction cross-section model issued from the International Atomic Energy Agency (IAEA) database was linked to Geant4 to accurately simulate the interaction of low energy bremsstrahlung photons with beryllium material. A benchmark test showed that a good agreement was achieved when comparing the emitted neutron flux spectra predicted by Geant4 and Fluka codes for a beryllium cylinder bombarded with a 5 MeV photon beam. The source optimization was achieved through a two stage Monte Carlo simulation. In the first stage, the distributions of the seven phase space coordinates of the bremsstrahlung photons at the boundaries of the tungsten target were determined. In the second stage events corresponding to photons emitted according to these distributions were tracked. A neutron yield of 4.8 × 1010 neutrons/mA/s was obtained at 20 cm from the beryllium target. A thermal neutron yield of 1.5 × 109 neutrons/mA/s was obtained after introducing a spherical shell of polyethylene as a neutron moderator.

  15. Advanced control of neutral beam injected power in DIII-D

    DOE PAGES

    Pawley, Carl J.; Crowley, Brendan J.; Pace, David C.; ...

    2017-03-23

    In the DIII-D tokamak, one of the most powerful techniques to control the density, temperature and plasma rotation is by eight independently modulated neutral beam sources with a total power of 20 MW. The rapid modulation requires a high degree of reproducibility and precise control of the ion source plasma and beam acceleration voltage. Recent changes have been made to the controls to provide a new capability to smoothly vary the beam current and beam voltage during a discharge, while maintaining the modulation capability. The ion source plasma inside the arc chamber is controlled through feedback from the Langmuir probesmore » measuring plasma density near the extraction end. To provide the new capability, the plasma control system (PCS) has been enabled to change the Langmuir probe set point and the beam voltage set point in real time. When the PCS varies the Langmuir set point, the plasma density is directly controlled in the arc chamber, thus changing the beam current (perveance) and power going into the tokamak. Alternately, the PCS can sweep the beam voltage set point by 20 kV or more and adjust the Langmuir probe setting to match, keeping the perveance constant and beam divergence at a minimum. This changes the beam power and average neutral particle energy, which changes deposition in the tokamak plasma. The ion separating magnetic field must accurately match the beam voltage to protect the beam line. To do this, the magnet current control accurately tracks the beam voltage set point. In conclusion, these new capabilities allow continuous in-shot variation of neutral beam ion energy to complement« less

  16. Experimental determination of beam quality factors, kQ, for two types of Farmer chamber in a 10 MV photon and a 175 MeV proton beam.

    PubMed

    Medin, Joakim; Ross, Carl K; Klassen, Norman V; Palmans, Hugo; Grusell, Erik; Grindborg, Jan-Erik

    2006-03-21

    Absorbed doses determined with a sealed water calorimeter operated at 4 degrees C are compared with the results obtained using ionization chambers and the IAEA TRS-398 code of practice in a 10 MV photon beam (TPR(20,10) = 0.734) and a 175 MeV proton beam (at a depth corresponding to the residual range, R(res) = 14.7 cm). Three NE 2571 and two FC65-G ionization chambers were calibrated in terms of absorbed-dose-to-water in (60)Co at the Swedish secondary standard dosimetry laboratory, directly traceable to the BIPM. In the photon beam quality, calorimetry was found to agree with ionometry within 0.3%, confirming the k(Q) values tabulated in TRS-398. In contrast, a 1.8% deviation was found in the proton beam at 6 g cm(-2) depth, suggesting that the TRS-398 tabulated k(Q) values for these two ionization chamber types are too high. Assuming no perturbation effect in the proton beam for the ionization chambers, a value for (w(air)/e)(Q) of 33.6 J C(-1) +/- 1.7% (k = 1) can be derived from these measurements. An analytical evaluation of the effect from non-elastic nuclear interactions in the ionization chamber wall indicates a perturbation effect of 0.6%. Including this estimated result in the proton beam would increase the determined (w(air)/e)(Q) value by the same amount.

  17. Design of multi-megawatt actively cooled beam dumps for the Neutral-Beam Engineering Test Facility

    SciTech Connect

    Paterson, J.A.; Koehler, G.; Wells, R.P.

    1981-10-01

    The Neutral Beam Engineering Test Facility will test Neutral Beam Sources up to 170 keV, 65 Amps, with 30 second beam-on times. For this application actively cooled beam dumps for both the neutral and ionized particles will be required. The dumps will be able to dissipate a wide range of power density profiles by utilizing a standard modular panel design which is incorporated into a moveable support structure. The thermal hydraulic design of the panels permit the dissipation of 2 kW/cm/sup 2/ anywhere on the panel surface. The water requirements of the dumps are optimized by restricting the flow to panel sections where the heat flux falls short of the design value. The mechanical design of the beam-dump structures is described along with tests performed on a prototype panel. The prototype tests were performed on two different panel designs, one manufactured by Mc Donnell Douglas (MDAC) the other by United Technologies (UT). The dissipation capabilities of the panels were tested at the critical regions to verify their use in the beam dump assemblies.

  18. Transverse emittance of a 2. 0-MeV RFQ beam with high brightness

    SciTech Connect

    Sander, O.R.; Boicourt, G.P.; Cottingame, W.B.

    1985-01-01

    One major purpose of the accelerator test stand (ATS) is to see if particle simulation codes can correctly predict the output beam parameters of our radio-frequency quadrupole (RFQ) linac. By injecting a very bright 100-keV beam (100 mA, 0.02 ..pi.. x cm x mrad) and comparing the measured output beam parameters with those predicted (using PARMTEQ), we can investigate PARMTEQ's performance in a high space-charge regime. PARMTEQ has successfully simulated the RFQ beam transmission and energy distribution; it is more difficult to simulate output transverse emittance. Transverse emittance is also difficult to measure because of the high-power-density beam. Special modification of our interceptive slit and collector equipment was required. This paper will compare measured transverse emittances with those predicted. 3 refs., 7 figs.

  19. Characterization of a 5-eV neutral atomic oxygen beam facility

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  1. An alpha particle measurement system using an energetic neutral helium beam in ITER (invited)

    SciTech Connect

    Sasao, M.; Tanaka, N.; Terai, K.; Kaneko, O.; Kisaki, M.; Kobuchi, T.; Tsumori, K.; Okamoto, A.; Kitajima, S.; Shinto, K.; Wada, M.

    2012-02-15

    An energetic helium neutral beam is involved in the beam neutralization measurement system of alpha particles confined in a DT fusion plasma. A full size strong-focusing He{sup +} ion source (2 A, the beam radius of 11.3 mm, the beam energy less than 20 keV). Present strong-focusing He{sup +} ion source shows an emittance diagram separated for each beamlet of multiple apertures without phase space mixing, despite the space charge of a beamlet is asymmetric and the beam flow is non-laminar. The emittance of beamlets in the peripheral region was larger than that of center. The heat load to the plasma electrode was studied to estimate the duty factor for the ITER application.

  2. Beam charge and current neutralization of high-charge-state heavy ions

    SciTech Connect

    Logan, B.G.; Callahan, D.A.

    1997-10-29

    High-charge-state heavy-ions may reduce the accelerator voltage and cost of heavy-ion inertial fusion drivers, if ways can be found to neutralize the space charge of the highly charged beam ions as they are focused to a target in a fusion chamber. Using 2-D Particle-In- Cell simulations, we have evaluated the effectiveness of two different methods of beam neutralization: (1) by redistribution of beam charge in a larger diameter, preformed plasma in the chamber, and (2), by introducing a cold-electron-emitting source within the beam channel at the beam entrance into the chamber. We find the latter method to be much more effective for high-charge-state ions.

  3. Ion Beam Neutralization Using FEAs and Mirror Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Nicolaescu, Dan; Sakai, Shigeki; Gotoh, Yasuhito; Ishikawa, Junzo

    2011-01-01

    Advanced implantation systems used for semiconductor processing require transportation of ion beams which are quasi-parallel and have low energy, such as (11B+,31P+,75As+) with energy in the range Eion = 200-1000 eV. Compensation of ion beam divergence may be obtained through electron injection and confinement in regions of non-uniform magnetic fields. Field emitter arrays with special properties are used as electron sources. The present study shows that electron confinement takes place in regions of gradient magnetic field, such as nearby analyzing, collimator and final energy magnets of the ion beam line. Modeling results have been obtained using Opera3D/Tosca/Scala. In regions of gradient magnetic field, electrons have helical trajectories which are confined like a cloud inside curved "magnetic bottles". An optimal range of positions with respect to the magnet for placing electron sources in gradient magnetic field has been shown to exist.

  4. Long-pulse power-supply system for EAST neutral-beam injectors

    NASA Astrophysics Data System (ADS)

    Liu, Zhimin; Jiang, Caichao; Pan, Junjun; Liu, Sheng; Xu, Yongjian; Chen, Shiyong; Hu, Chundong; NBI Team

    2017-05-01

    The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences): one for the neutral-beam test stand and two for the EAST neutral-beam injectors (NBI-1 and NBI-2, respectively). Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 keV was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.

  5. Numerical simulation and optimization of the variable energy 60-1000 MeV proton beams at PNPI synchrocyclotron for testing the radiation resistance of electronics

    NASA Astrophysics Data System (ADS)

    Artamonov, S. A.; Ivanov, E. M.; Ivanov, N. A.; Lebedeva, J. S.; Riabov, G. A.

    2017-01-01

    A universal center for testing electronic components (ECs) for the needs of aviation and space is created in the SC-1000 Petersburg Nuclear Physics Institute, National Research Centre "Kurchatov Institute" (PNPI NRC KI). One of the main instruments of these tests is variable energy protons beams. This paper presents Monte Carlo simulation results for a proton beam with energy of 1000 MeV passing through copper and tungsten degraders, and defines the length of these degraders to obtain energies of 60, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 MeV. Detailed studies of further transmission of the proton beams along the beam line using the copper degrader are accomplished. Basic theoretical parameters for each proton beam, such as the intensity, the energy heterogeneity, beam size, and uniformity of its spatial distribution are obtained.

  6. [Dose distributions of fast electrons with an energy of 7-24 Mev in electromagnetic beam formation].

    PubMed

    Shambulov, R S; Khvan, G V; Saĭbekov, T S; Azhigaliev, N A; Shuinbekov, A D

    1983-03-01

    The formation of a wide beam is found necessary for a clinical application of a fast electron beam. A method of formation using thin dispersion foils is the most common one. An electromagnetic method of formation has been worked out, and dose distributions of fast electrons formed by this method have been compared in the tissue equivalent medium with those formed with the help of dispersion foils. The effect of some of the individual units of the forming device in these two methods of formation has been assessed. The experiment was conducted on medical beta-trons B-15 and B-5M-25 manufactured in the USSR. The depth dose distributions of fast electrons along the beam central axis in the electromagnetic formation for electrons with an energy of 7-24 MEV, field 8 X 10 cm and DSS = 90 cm are presented. It has been established that the beam intensity in the electromagnetic formation is higher than in the utilization of dispersion foils. Depth dose distribution is better in the electromagnetic formation than in the utilization of dispersion foils.

  7. Design study of the ESS-Bilbao 50 MeV proton beam line for radiobiological studies

    NASA Astrophysics Data System (ADS)

    Huerta-Parajon, M.; Martinez-Ballarin, R.; Abad, E.

    2015-02-01

    The ESS-Bilbao proton accelerator facility has been designed fulfilling the European Spallation Source (ESS) specifications to serve as the Spanish contribution to the ESS construction. Furthermore, several applications of the ESS-Bilbao proton beam are being considered in order to contribute to the knowledge in the field of radiobiology, materials and aerospace components. Understanding of the interaction of radiation with biological systems is of vital importance as it affects important applications such as cancer treatment with ion beam therapy among others. ESS-Bilbao plans to house a facility exclusively dedicated to radiobiological experiments with protons up to 50 MeV. Beam line design, optimisation and initial calculations of flux densities and absorbed doses were undertaken using the Monte Carlo simulation package FLUKA. A proton beam with a flux density of about 106 protons/cm2 s reaches the water sample with a flat lateral distribution of the dose. The absorbed dose at the pristine Bragg peak calculated with FLUKA is 2.4 ± 0.1 Gy in 1 min of irradiation time. This value agrees with the clinically meaningful dose rates, i.e. around 2 Gy/min, used in hadrontherapy. Optimisation and validation studies in the ESS-Bilbao line for radiobiological experiments are detailed in this article.

  8. New techniques for calculating heat and particle source rates due to neutral-beam injection in axisymmetric tokamaks

    SciTech Connect

    Goldston, R.J.; McCune, D.C.; Towner, H.H.; Davis, S.L.; Hawryluk, R.J.; Schmidt, G.L.

    1981-02-01

    A set of numerical techniques are described for calculating heat and particle source rates due to neutral beam injection in axisymmetric tokamaks. While these techniques consume a substantial amount of computer time, they take into account a number of significant, and normally neglected, effects. Examples of these effects are reionization of escaping charge exchanged beam particles, finite fast ion orbit excursions, beam deposition through collisions of beam neutrals with circulating beam ions, and the transport of thermal neutrals in the plasma due to charge changing collisions with beam ions.

  9. Production of intense negative hydrogen beams with polarized nuclei by selective neutralization of negative ions

    DOEpatents

    Hershcovitch, Ady

    1987-01-01

    A process for selectively neutralizing H.sup.- ions in a magnetic field to produce an intense negative hydrogen ion beam with spin polarized protons. Characteristic features of the process include providing a multi-ampere beam of H.sup.- ions that are intersected by a beam of laser light. Photodetachment is effected in a uniform magnetic field that is provided around the beam of H.sup.- ions to spin polarize the H.sup.- ions and produce first and second populations or groups of ions, having their respective proton spin aligned either with the magnetic field or opposite to it. The intersecting beam of laser light is directed to selectively neutralize a majority of the ions in only one population, or given spin polarized group of H.sup.- ions, without neutralizing the ions in the other group thereby forming a population of H.sup.- ions each of which has its proton spin down, and a second group or population of H.sup.o atoms having proton spin up. Finally, the two groups of ions are separated from each other by magnetically bending the group of H.sup.- ions away from the group of neutralized ions, thereby to form an intense H.sup.- ion beam that is directed toward a predetermined objective.

  10. Particle Dynamics in the Magnet Region of the DIII-D Neutral Beam System

    NASA Astrophysics Data System (ADS)

    Blackford, C. A.; Crowley, B. J.; Rauch, J. M.; Scoville, J. T.

    2016-10-01

    The Neutral Beam system on the DIII-D tokamak consists of eight ion sources on four beam lines using the Common Long Pulse Source (CLPS) developed at Berkeley in the 1980s. This poster presents the results of modeling efforts aimed to understand the anomalous power deposition in the bending magnet region of the neutral beam system at DIII-D. The code tracks individual particles in 3D electric and magnetic fields. In these fields, the particles intercept solid boundaries and deposit power on the magnet pole shields as well as various collimators, the ion dump, and the beam dump calorimeter. This code allows investigation of phenomena including the non-uniformity of the magnetic field, the space charge effects on the neutral beam, and deviant ion trajectories within the system. These phenomena are expected to contribute largely to the power deposition within the bending magnet region. Results of the analysis may lead to adjustments that could increase the efficiency of the neutral beam system at the DIII-D facility. Work supported by U.S. DOE under DE-FC02-04ER54698.

  11. Theory and simulations of neutralization and focusing of ICF ion beams

    SciTech Connect

    Lemons, D.S.; Jones, M.E.

    1985-10-01

    Inertial Confinement Fusion (ICF) ion beams must be focused to a small spot during final propagation to the target. In general, both beam emittance and space charge limit the achievable spot size. Here we consider the latter and how its effect can be eliminated by injecting into the target chamber electrons which are comoving and coexstensive with the ions. Unlike focusing an ion beam through a neutralizing plasma channel, the present propagation mode requires a hard vacuum (10/sup -4/ to 10/sup -5/ Torr) target chamber into which both ions and electrons are injected, and thus avoids possibly deleterious beam plasma interactions.

  12. Development of micro-contact printing of osteosarcoma cells using MeV ion beam lithography

    NASA Astrophysics Data System (ADS)

    Sangyuenyongpipat, Somjai; Marjomäki, Varpu; Ikonen, Stiina; Sajavaara, Timo; Ananda Sagari, A. R.; Gorelick, Sergey; Laitinen, Mikko; Whitlow, Harry J.

    2009-06-01

    For investigation of spatial effects in signalling between cells and also signal substances that trigger cell proliferation and behaviour we are developing a micro Contact Printing process (μCP). In order to allow printing of cells stamps with high aspect ratio are required and these have been fabricated using Programmed Proximity Aperture Lithography (PPAL) with 3 MeV 4He ions to produce PMMA masters for casting the stamps in PDMS. A simple printing device was developed and the first results using this to print human osteosarcoma cells is demonstrated.

  13. Bunch Shape Measurement of 181 MeV Beam in J-PARC Linac

    NASA Astrophysics Data System (ADS)

    Miura, Akihiko; Feschenko, Alexander V.; Mirzojan, Alexander N.; Miyao, Tomoaki; Ouchi, Nobuo; Maruta, Tomofumi; Liu, Yong; Oguri, Hidetomo; Ikegami, Masanori; Hasegawa, Kazuo

    In the Japan Proton Accelerator Research Complex linac, an energy upgrade project was started in 2009 using annular-ring coupled structure (ACS) linac cavities. We decided to use bunch shape monitors (BSM) for monitoring longitudinal beam width measurement to achieve longitudinal matching using two bunchers located upstream of the ACS cavities, where the radio frequency jumps from 324 to 972 MHz. Three BSMs were fabricated and installed in the original beam line. The BSMs were commissioned with the beam and their operability was demonstrated. In this study, we introduce the mechanism of the BSMs, its operability, measurement results with the 181 MeV beam, and consistency check with the respective cavity amplitude. Furthermore, we describe the operational vacuum conditions and outline the improvements to the BSMs' vacuum system.

  14. Confinement and dynamics of neutral beam injected fast ions in the MST Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Liu, D.; Almagri, F.; Anderson, J. K.; den Hartog, D. J.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Fiksel, G.; Deichuli, P.; Davydenko, V. I.; Ivanov, A. A.; Polosatkin, S. V.; Stupishin, N.; Andre, R.; McCune, D.

    2010-11-01

    The new 1MW neutral beam injector (97% H, 3% D) on MST provides a good test-bed for study of fast ions in the RFP. Analysis of the D-D fusion neutron flux decay at beam turn-off reveals that the confinement time of the fast ions is at least 10 ms, ten-fold larger than the thermal conferment times for particles and energy in standard stochastic plasmas. Also, the fast ion confinement increases with magnetic field strength. Dependence of fast ion confinement on plasma parameters, beam energy, and injection direction will be characterized and compared with TRANSP simulations. In addition, an advanced neutral particle analyzer and a prototype of fast ion charge exchange spectroscopy are under construction to measure neutralized fast ions and induced Doppler-shifted Hα light, respectively, thereby resolving fast ion density and energy distribution. Initial measurements of fast-ion dynamics during magnetic reconnection events will be presented.

  15. Sustaining neutral beam power supply system for the Mirror Fusion Test Facility

    SciTech Connect

    Eckard, R.D.; Wilson, J.H.; Van Ness, H.W.

    1980-01-01

    In late August 1978, a fixed price procurement contract for $25,000,000 was awarded to Aydin Energy Division, Palo Alto, California, for the design, manufacture, installation and acceptance testing of the Lawrence Livermore National Laboratory Mirror Fusion Test Facility (MFTF) Sustaining Neutral Beam Power Supply System (SNBPSS). This system of 24 power supply sets will provide the conditioned power for the 24 neutral beam source modules. Each set will provide the accel potential the arc power, the filament power, and the suppressor power for its associated neutral beam source module. The design and development of the SNBPSS has progressed through the final design phase and is now in production. Testing of the major sub-assembly power supply is proceeding at Aydin and the final acceptance testing of the first two power supplies at LLNL is expected to be completed this year.

  16. Neutral beam injector for 475 keV MARS sloshing ions

    SciTech Connect

    Goebel, D.M.; Hamilton, G.W.

    1983-12-13

    A neutral beam injector system which produces 5 MW of 475 keV D/sup 0/ neutrals continuously on target has been designed. The beamline is intended to produce the sloshing ion distribution required in the end plug region of the conceptual MARS tandem mirror commercial reactor. The injector design utilizes the LBL self-extraction negative ion source and Transverse Field Focusing (TFF) accelerator to generate a long, ribbon ion beam. A laser photodetachment neutralizer strips over 90% of the negative ions. Magnetic and neutron shield designs are included to exclude the fringe fields of the end plug and provide low activation by the neutron flux from the target plasma. The use of a TFF accelerator and photodetachment neutralizer produces a total system electrical efficiency of about 63% for this design.

  17. Hysteresis effects in the formation of a neutralizing beam plasma at low ion energy

    NASA Astrophysics Data System (ADS)

    Rafalskyi, Dmytro; Aanesland, Ane

    2013-11-01

    In this paper, the PEGASES II thruster prototype is used as an ion source generating low-energy (<300\\ \\text{eV}) positive Ar ion beam, extracted without an external neutralizer. The ions are extracted and accelerated from the source using a two-grid system. The extracted positive ion beam current is measured on a large beam target that can be translated along the acceleration axis. The ion beam current shows a stepwise transition from a low-current to a high-current extraction regime with hysteresis. The hysteresis region depends strongly upon the beam target position. Langmuir probe measurements in the plume show high plasma potentials and low plasma densities in the low-current mode, while the plasma potential drops and the density increases in the high-current mode. The ion energy distribution functions of the beam are measured for different regimes of ion extraction. The ion beam extracted in the high-current mode is indicated by the presence of an additional low-energy peak corresponding to ions from an ion-beam plasma created in the downstream chamber, as well as 10-20 times higher intensity of the primary ion beam peak. The hysteresis behavior is explained by the formation of a downstream neutralizing beam plasma, that depends on the target position and pressure in agreement with a Paschen-like breakdown by secondary electrons. The obtained results are of high relevance for further development of the PEGASES thruster, as well as for improving existing neutralizer-free concepts of the broad-beam ion sources.

  18. Real-Time Variation of the Injected Neutral Beam Energy on the DIII-D Tokamak

    NASA Astrophysics Data System (ADS)

    Scoville, J. T.; Crowley, B. J.; Pace, D. C.; Rauch, J. M.

    2016-10-01

    A powerful new technique for smoothly controlling the time evolution of injected energy from neutral beams has recently been implemented on the DIII-D tokamak. Upgrades to the high voltage circuitry of the neutral beams and to the tokamak's Plasma Control System have enabled the first-ever continuous variation of beam voltage during plasma shots. This avoids the perturbative effects of pulse modulation, which was the previously employed method for changing the injected beam power. The new technique allows much finer control of the injected energy, with beam voltage able to be varied smoothly over a 20 kV range (within the 45-85 kV beam operating space) in 0.5 sec. This capability enables fundamentally new experiments that require precise control of beam ion phase space, including the minimization of undesirable energetic ion instabilities and scans across low torque regimes at fixed power. We present a description of the beam system modifications and initial results from plasma experiments using the new variable beam energy capability on the DIII-D tokamak. Work supported by U.S. DOE under DE-FC02-04ER54698.

  19. Tangential neutral-beam-driven instabilities in the Princeton beta experiment

    SciTech Connect

    Heidbrink, W.W.; Bol, K.; Buchenauer, D.; Fonck, R.; Gammel, G.; Ida, K.; Kaita, R.; Kaye, S.; Kugel, H.; LeBlanc, B.

    1986-07-01

    During tangential neutral beam injection into the PBX tokamak, bursts of two types of instabilities are observed. One instability occurs in the frequency range 120-210 kHz and the other oscillates predominately near the frequency of bulk plasma rotation (20-30 kHz). Both instabilities correlate with drops in neutron emission and burst in charge-exchange neutral flux, indicating that beam ions are removed from the center of the plasma by the instabilities. The central losses are comparable to the losses induced by the fishbone instability during perpendicular injection.

  20. Progress in computer-assisted diagnosis and control of neutral beam lines

    SciTech Connect

    Theil, E.; Elischer, V.; Fiddler, J.; Jacobs, N.J.D.; Jacobson, V.; Lawhorn, R.; Uber, D.; Wilner, D.

    1980-09-01

    This paper discusses the principles that have guided the development of a computerized diagnostic and control system for both the Neutral Beam Systems Test Facility at Lawrence Berkeley Laboratory and the Doublet III neutral beams at the General Atomic Company. The emphasis is not on the particular details of the implementation, but on general considerations which have influenced the design criteria for the system. Foremost among these are the requirements of an appropriate human interface to the system, and effective use of a relational data base. Examples are used to illustrate how these principles are carried out in practice. A systems view of diagnostic programs is suggested in the light of our experience.

  1. Luminescence properties of pure and doped CaSO4 nanorods irradiated by 15 MeV e-beam

    NASA Astrophysics Data System (ADS)

    Salah, Numan; Alharbi, Najlaa D.; Enani, Mohammad A.

    2014-01-01

    Calcium sulfate (CaSO4) doped with proper activators is a highly sensitive phosphor used in different fields mainly for radiation dosimetry, lighting and display applications. In this work pure and doped nanorods of CaSO4 were produced by the co-precipitation technique. Samples from this material doped with Ag, Cu, Dy, Eu and Tb were exposed to different doses of 15 MeV e-beam and studied for their thermoluminesence (TL) and photoluminescence (PL) properties. Color center formation leading to PL emissions were investigated before and after e-beam irradiation. The samples doped with rare earths elements (i.e. Dy, Eu and Tb) were observed to have thinner nanorods than the other samples and have higher absorption in the UV region. The Ag and Tb doped samples have poor TL response to e-beam, while those activated by Cu, Dy and Eu have strong glow peaks at around 123 °C. Quite linear response curves in the whole studied exposures i.e. 0.1-100 Gy were also observed in Cu and Dy doped samples. The PL results show that pure CaSO4 nanorods have active color centers without irradiation, which could be enriched/modified by these impurities mainly rare earths and further enhanced by e-beam irradiation. Eu3+ → Eu2+ conversion is clearly observed in Eu doped sample after e-beam irradiation. These results show that these nanorods might be useful in lighting and display devices development.

  2. Variations in the Processing of DNA Double-Strand Breaks Along 60-MeV Therapeutic Proton Beams

    PubMed Central

    Chaudhary, Pankaj; Marshall, Thomas I.; Currell, Frederick J.; Kacperek, Andrzej; Schettino, Giuseppe; Prise, Kevin M.

    2016-01-01

    Purpose To investigate the variations in induction and repair of DNA damage along the proton path, after a previous report on the increasing biological effectiveness along clinically modulated 60-MeV proton beams. Methods and Materials Human skin fibroblast (AG01522) cells were irradiated along a monoenergetic and a modulated spread-out Bragg peak (SOBP) proton beam used for treating ocular melanoma at the Douglas Cyclotron, Clatterbridge Centre for Oncology, Wirral, Liverpool, United Kingdom. The DNA damage response was studied using the 53BP1 foci formation assay. The linear energy transfer (LET) dependence was studied by irradiating the cells at depths corresponding to entrance, proximal, middle, and distal positions of SOBP and the entrance and peak position for the pristine beam. Results A significant amount of persistent foci was observed at the distal end of the SOBP, suggesting complex residual DNA double-strand break damage induction corresponding to the highest LET values achievable by modulated proton beams. Unlike the directly irradiated, medium-sharing bystander cells did not show any significant increase in residual foci. Conclusions The DNA damage response along the proton beam path was similar to the response of X rays, confirming the low-LET quality of the proton exposure. However, at the distal end of SOBP our data indicate an increased complexity of DNA lesions and slower repair kinetics. A lack of significant induction of 53BP1 foci in the bystander cells suggests a minor role of cell signaling for DNA damage under these conditions. PMID:26452569

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

    DOE PAGES

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

    2016-10-12

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

  4. In-vacuum sensors for the beamline components of the ITER neutral beam test facility

    SciTech Connect

    Dalla Palma, M. Pasqualotto, R.; Spagnolo, S.; Spolaore, M.; Sartori, E.; Veltri, P.

    2016-11-15

    Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strain gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.

  5. In-vacuum sensors for the beamline components of the ITER neutral beam test facility

    NASA Astrophysics Data System (ADS)

    Dalla Palma, M.; Pasqualotto, R.; Sartori, E.; Spagnolo, S.; Spolaore, M.; Veltri, P.

    2016-11-01

    Embedded sensors have been designed for installation on the components of the MITICA beamline, the prototype ITER neutral beam injector (Megavolt ITER Injector and Concept Advancement), to derive characteristics of the particle beam and to monitor the component conditions during operation for protection and thermal control. Along the beamline, the components interacting with the particle beam are the neutralizer, the residual ion dump, and the calorimeter. The design and the positioning of sensors on each component have been developed considering the expected beam-surface interaction including non-ideal and off-normal conditions. The arrangement of the following instrumentation is presented: thermal sensors, strain gages, electrostatic probes including secondary emission detectors, grounding shunt for electrical currents, and accelerometers.

  6. Development of a negative ion-based neutral beam injector in Novosibirsk

    NASA Astrophysics Data System (ADS)

    Ivanov, A. A.; Abdrashitov, G. F.; Anashin, V. V.; Belchenko, Yu. I.; Burdakov, A. V.; Davydenko, V. I.; Deichuli, P. P.; Dimov, G. I.; Dranichnikov, A. N.; Kapitonov, V. A.; Kolmogorov, V. V.; Kondakov, A. A.; Sanin, A. L.; Shikhovtsev, I. V.; Stupishin, N. V.; Sorokin, A. V.; Popov, S. S.; Tiunov, M. A.; Belov, V. P.; Gorbovsky, A. I.; Kobets, V. V.; Binderbauer, M.; Putvinski, S.; Smirnov, A.; Sevier, L.

    2014-02-01

    A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

  7. Development of a negative ion-based neutral beam injector in Novosibirsk.

    PubMed

    Ivanov, A A; Abdrashitov, G F; Anashin, V V; Belchenko, Yu I; Burdakov, A V; Davydenko, V I; Deichuli, P P; Dimov, G I; Dranichnikov, A N; Kapitonov, V A; Kolmogorov, V V; Kondakov, A A; Sanin, A L; Shikhovtsev, I V; Stupishin, N V; Sorokin, A V; Popov, S S; Tiunov, M A; Belov, V P; Gorbovsky, A I; Kobets, V V; Binderbauer, M; Putvinski, S; Smirnov, A; Sevier, L

    2014-02-01

    A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

  8. Scattering process for the system 7Be + 58Ni at 23.2 MeV beam energy

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Torresi, D.; Fierro, N.; Acosta, L.; Boiano, A.; Boiano, C.; Glodariu, T.; Guglielmetti, A.; La Commara, M.; Martel, I.; Mazzocchi, C.; Molini, P.; Pakou, A.; Parascandolo, C.; Parker, V. V.; Patronis, N.; Pierroutsakou, D.; Romoli, M.; Sanchez-Benitez, A. M.; Sandoli, M.; Signorini, C.; Silvestri, R.; Soramel, F.; Stiliaris, E.; Strano, E.; Stroe, L.; Zerva, K.

    2013-03-01

    We measured for the first time the scattering process of 7Be nuclei from a 58Ni target at 23.2 MeV beam energy. The experiment was performed at the Laboratori Nazionali di Legnaro (LNL, Italy), where the 7Be Radioactive Ion Beam was in-flight produced with the facility EXOTIC. Charged reaction products were detected by means of the detector array DINEX, arranged in a cylindrical configuration around the target to ensure a polar angle coverage in the ranges θcm = 40°-80° and 110°-150°. The scattering differential cross section was analyzed within the optical model formalism with the coupled-channel code FRESCO to extract the total reaction cross section. The result was compared with those obtained at lower beam energies in an earlier experiment performed at the University of Notre Dame (USA). At the present stage of our analysis, the two data sets were found to be not fully consistent each other.

  9. Validation of nuclear models in Geant4 using the dose distribution of a 177 MeV proton pencil beam.

    PubMed

    Hall, David C; Makarova, Anastasia; Paganetti, Harald; Gottschalk, Bernard

    2016-01-07

    A proton pencil beam is associated with a surrounding low-dose envelope, originating from nuclear interactions. It is important for treatment planning systems to accurately model this envelope when performing dose calculations for pencil beam scanning treatments, and Monte Carlo (MC) codes are commonly used for this purpose. This work aims to validate the nuclear models employed by the Geant4 MC code, by comparing the simulated absolute dose distribution to a recent experiment of a 177 MeV proton pencil beam stopping in water. Striking agreement is observed over five orders of magnitude, with both the shape and normalisation well modelled. The normalisations of two depth dose curves are lower than experiment, though this could be explained by an experimental positioning error. The Geant4 neutron production model is also verified in the distal region. The entrance dose is poorly modelled, suggesting an unaccounted upstream source of low-energy protons. Recommendations are given for a follow-up experiment which could resolve these issues.

  10. Physics of Neutralization of Intense High-Energy Ion Beam Pulses by Electrons

    SciTech Connect

    Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

    2010-04-28

    Neutralization and focusing of intense charged particle beam pulses by electrons forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self- magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

  11. Physics of neutralization of intense high-energy ion beam pulses by electrons

    SciTech Connect

    Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Lee, E. P.; Friedman, A.

    2010-05-15

    Neutralization and focusing of intense charged particle beam pulses by electrons form the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100 G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating through the

  12. Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

    SciTech Connect

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

    2009-09-03

    Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

  13. Measurement of Neutral Current Neutral Pion Production on Carbon in a Few-GeV Neutrino Beam

    SciTech Connect

    Kurimoto, Yoshinori

    2010-01-01

    Understanding of the π0 production via neutrino-nucleus neutral current interaction in the neutrino energy region of a few GeV is essential for the neutrino oscillation experiments. In this thesis, we present a study of neutral current π0 production from muon neutrinos scattering on a polystyrene (C8H8) target in the SciBooNE experiment. All neutrino beam data corresponding to 0.99 × 1020 protons on target have been analyzed. We have measured the cross section ratio of the neutral current π0 production to the total charge current interaction and the π0 kinematic distribution such as momentum and direction. We obtain [7.7 ± 0.5(stat.) ± 0.5(sys.)] × 10-2 as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein- Sehgal model, which is generally used for the Monte Carlo simulation by many neutrino oscillation experiments. We achieve less than 10 % uncertainty which is required for the next generation search for νµ → νe oscillation. The spectrum shape of the π0 momentum and the distribution of the π0 emitted angle agree with the prediction, which means that not only the Rein-Sehgal model but also the intra-nuclear interaction models describe our data well. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (1.17 ± 0.23 ) × 10-2 based on the Rein and Sehgal model. The result gives the evidence for non-zero coherent pion production via neutral current interaction at the mean neutrino energy of 1.0 GeV.

  14. Parameterization of the electron beam output factors of a 25-MeV linear accelerator

    SciTech Connect

    McParland, B.J.

    1987-07-01

    A new parameterization of the output factors of an electron beam has been developed. The output factors for the electron beams of an AECL Therac-25 have been determined for a variety of square and rectangular fields using ionization measurements and thermoluminescent dosimetry. The data were then least-squares fit by a semiempirical equation which treats the two field dimensions as variables. Such a parameterization allows computer-generated tables of output factors to be manufactured. The calculated values agree with the measured data in most cases to within the +- 1% experimental uncertainty. A comparison between this method of calculating output factors and two conventional methods is also presented.

  15. A parameterization of the electron beam output factors of a 25-MeV linear accelerator.

    PubMed

    McParland, B J

    1987-01-01

    A new parameterization of the output factors of an electron beam has been developed. The output factors for the electron beams of an AECL Therac-25 have been determined for a variety of square and rectangular fields using ionization measurements and thermoluminescent dosimetry. The data were then least-squares fit by a semiempirical equation which treats the two field dimensions as variables. Such a parameterization allows computer-generated tables of output factors to be manufactured. The calculated values agree with the measured data in most cases to within the +/- 1% experimental uncertainty. A comparison between this method of calculating output factors and two conventional methods is also presented.

  16. Photoluminescence from 20 MeV electron beam irradiated homogeneous SiOx and composite Si-SiOx films

    NASA Astrophysics Data System (ADS)

    Nesheva, D.; Šćepanović, M.; Grujić-Brojčin, M.; Dzhurkov, V.; Kaschieva, S.; Bineva, I.; Dmitriev, S. N.; Popović, Z. V.

    2016-10-01

    The effect of 20 MeV electron irradiation on the room temperature photoluminescence from homogeneous SiOx and composite Si-SiOx films, containing amorphous or crystalline Si nanoparticles, is studied. Layers with x = 1.5 and 1.7 and thickness of 200 nm were deposited on crystalline silicon substrates by thermal evaporation of SiO in vacuum. Film annealing in an inert atmosphere at 700 oC or 1000 oC for 60 min was applied to grow amorphous or crystalline silicon nanoparticles, respectively, in a SiOx matrix. Samples from all types of films were irradiated with 20 MeV electrons at close to room temperature and a fluence of 2.4x1014 el.cm-2. Photoluminescence was measured under excitation with the 488 nm line of an Ar+ laser. The electron irradiation causes a decrease of the integrated photoluminescence intensity in composite samples with initial x = 1.7 containing amorphous or crystalline nanoparticles and x = 1.5 samples with Si nanocrystals. The electron irradiation of x = 1.5 samples with amorphous nanoparticles slightly increases the photoluminescence intensity. The obtained results are discussed in terms of electron beam induced phase separation and Si nanoparticle size increase.

  17. Design, performance, and calculated error of a Faraday cup for absolute beam current measurements of 600-MeV protons

    NASA Technical Reports Server (NTRS)

    Beck, S. M.

    1975-01-01

    A mobile self-contained Faraday cup system for beam current measurments of nominal 600 MeV protons was designed, constructed, and used at the NASA Space Radiation Effects Laboratory. The cup is of reentrant design with a length of 106.7 cm and an outside diameter of 20.32 cm. The inner diameter is 15.24 cm and the base thickness is 30.48 cm. The primary absorber is commercially available lead hermetically sealed in a 0.32-cm-thick copper jacket. Several possible systematic errors in using the cup are evaluated. The largest source of error arises from high-energy electrons which are ejected from the entrance window and enter the cup. A total systematic error of -0.83 percent is calculated to be the decrease from the true current value. From data obtained in calibrating helium-filled ion chambers with the Faraday cup, the mean energy required to produce one ion pair in helium is found to be 30.76 + or - 0.95 eV for nominal 600 MeV protons. This value agrees well, within experimental error, with reported values of 29.9 eV and 30.2 eV.

  18. Ion Beam Induced Charge Collection (IBICC) from Integrated Circuit Test Structures Using a 10 MeV Carbon Microbeam

    SciTech Connect

    Aton, T.J.; Doyle, B.L.; Duggan, J.L.; El Bouanani, M.; Guo, B.N.; McDaniel, F.D.; Renfrow, S.N.; Walsh, D.S.

    1998-11-18

    As future sizes of Integrated Circuits (ICs) continue to shrink the sensitivity of these devices, particularly SRAMs and DRAMs, to natural radiation is increasing. In this paper, the Ion Beam Induced Charge Collection (IBICC) technique is utilized to simulate neutron-induced Si recoil effects in ICS. The IBICC measurements, conducted at the Sandia National Laboratories employed a 10 MeV carbon microbeam with 1pm diameter spot to scan test structures on specifically designed ICS. With the aid of layout information, an analysis of the charge collection efficiency from different test areas is presented. In the present work a 10 MeV Carbon high-resolution microbeam was used to demonstrate the differential charge collection efficiency in ICS with the aid of the IC design Information. When ions strike outside the FET, the charge was only measured on the outer ring, and decreased with strike distance from this diode. When ions directly strike the inner and ring diodes, the collected charge was localized to these diodes. The charge for ions striking the gate region was shared between the inner and ring diodes. I The IBICC measurements directly confirmed the interpretations made in the earlier work.

  19. Simulation of Electron Beam Dynamics in the 22 MeV Accelerator for a Coherent Electron Cooling Proof of Principle Experiment

    SciTech Connect

    Owen, Justin

    2013-12-01

    Coherent electron cooling (CeC) offers a potential new method of cooling hadron beams in colliders such as the Relativistic Heavy Ion Collider (RHIC) or the future electron ion collider eRHIC. A 22 MeV linear accelerator is currently being built as part of a proof of principle experiment for CeC at Brookhaven National Laboratory (BNL). In this thesis we present a simulation of electron beam dynamics including space charge in the 22 MeV CeC proof of principle experiment using the program ASTRA (A Space charge TRacking Algorithm).

  20. Formation of uniformly sized gold nanoparticles over graphene by MeV electron beam irradiation for transparent conducting films

    SciTech Connect

    Kim, Yooseok; Lee, Su-il; Youb Lee, Seung; Cha, Myoung-Jun; Song, Wooseok; Sung Jung, Dae; Park, Chong-Yun

    2013-06-03

    Highly flexible, transparent, and conducting sheet was fabricated by decoration of uniformly sized gold nanoparticles (Au NPs) with high-density on large-area graphene by MeV electron beam irradiation (MEBI) at room temperature under ambient conditions. The Au NPs with an average size of 13.6 ± 3.5 nm were clearly decorated on the graphene after MEBI with an irradiation energy of 1.0 MeV. The sheet resistances of the Au NPs/graphene significantly decreased. For the Au NPs/trilayer graphene, the sheet resistance reached to ∼45 Ω/sq, and the optical transmittance was ∼90.2% which is comparable to that of conventional indium tin oxide film.

  1. New electron beam-dump experiments to search for MeV to few-GeV dark matter

    NASA Astrophysics Data System (ADS)

    Izaguirre, Eder; Krnjaic, Gordan; Schuster, Philip; Toro, Natalia

    2013-12-01

    In a broad class of consistent models, MeV to few-GeV dark matter interacts with ordinary matter through weakly coupled GeV scale mediators. We show that a suitable meter scale (or smaller) detector situated downstream of an electron beam dump can sensitively probe dark matter interacting via sub-GeV mediators, while B-factory searches cover the 1-5 GeV range. Combined, such experiments explore a well-motivated and otherwise inaccessible region of dark matter parameter space with sensitivity several orders of magnitude beyond existing direct detection constraints. These experiments would also probe invisibly decaying new gauge bosons (“dark photons”) down to kinetic mixing of ɛ˜10-4, including the range of parameters relevant for explaining the (g-2)μ discrepancy. Sensitivity to other long-lived dark sector states and to new millicharge particles would also be improved.

  2. Reactions induced by 18 MeV 6He beam on 6Li, 7Li and 12C

    NASA Astrophysics Data System (ADS)

    Milin, M.; Cherubini, S.; Davinson, T.; Di Pietro, A.; Figuera, P.; Miljanić, Đ.; Musumarra, A.; Ninane, A.; Ostrowski, A. N.; Pellegriti, M. G.; Shotter, A. C.; Soić, N.; Spitaleri, C.; Zadro, M.

    2004-12-01

    The 6He+ 6,7Li and 6He+ 12C scattering and reactions have been studied using a 18 MeV 6He beam. Experimental results for the elastic scattering on all three targets are in fair agreement with optical model predictions, using the potentials found in the analysis of the 6Li scattering on the same targets and at close energies. Large cross sections are observed for α-transfer reactions to some states of 10Be. The sequential decay reactions 6He+ 6Li→ 6He+ α+ d, 6He+ 6Li→2 α+ t+ n, 6He+ 7Li→ 6He+ α+ t and 6He+ 12C→ 10Be+2 α were clearly seen and analysing them α-clustering of some states in 6Li, 7Li, 8Be, 9Be, 10Be and 14C was recognized.

  3. Neutral beam spectroscopy for equilibrium and stability measurements for the PEGASUS toroidal experiment (abstract)

    SciTech Connect

    Thorson, T.; Fonck, R.; Lewicki, B.

    1999-01-01

    An optical neutral beam spectroscopy system is being designed to provide equilibrium and stability measurements for the PEGASUS toroidal experiment. Spatially localized measurements of the electron temperature and plasma density are possible by observing the intensity of the collisionally induced neutral beam fluorescence. In a helium beam, the population of the singlet levels are relatively independent of the plasma temperature compared to the triplet levels. Therefore, the ratio of intensities of a triplet transition (e.g., 3{sup 3}S{r_arrow}2{sup 3}P, {lambda}=706.5 nm) to a singlet transition (e.g., 3{sup 1}P{r_arrow}2{sup 1}S, {lambda}=501.6 nm) provides a measure of the local plasma temperature for the range 10 eV{lt}T{sub e}{lt}1.0 keV. The plasma density profile can be inferred from the attenuation of the beam fluorescence signal as the beam passes through the plasma. Additionally in a deuterium beam, the local plasma density can be directly inferred from the local radial gradient in the observed beam fluorescence signal. Plasma stability will be studied with localized magnetohydrodynamics measurements via beam emission spectroscopy, which otherwise is problematic for low-field spherical plasmas. {copyright} {ital 1999 American Institute of Physics.}

  4. Studies on space charge neutralization and emittance measurement of beam from microwave ion source

    SciTech Connect

    Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S. E-mail: vspandit12@gmail.com

    2015-11-15

    A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

  5. High-flux source of low-energy neutral beams using reflection of ions from metals

    NASA Technical Reports Server (NTRS)

    Cuthbertson, John W.; Motley, Robert W.; Langer, William D.

    1992-01-01

    Reflection of low-energy ions from surfaces can be applied as a method of producing high-flux beams of low-energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial RF plasma source. The beam provides a large enough flux to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4-32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.

  6. High-flux source of low-energy neutral beams using reflection of ions from metals

    NASA Technical Reports Server (NTRS)

    Cuthbertson, John W.; Motley, Robert W.; Langer, William D.

    1992-01-01

    Reflection of low-energy ions from surfaces can be applied as a method of producing high-flux beams of low-energy neutral particles, and is an important effect in several areas of plasma technology, such as in the edge region of fusion devices. We have developed a beam source based on acceleration and reflection of ions from a magnetically confined coaxial RF plasma source. The beam provides a large enough flux to allow the energy distribution of the reflected neutrals to be measured despite the inefficiency of detection, by means of an electrostatic cylindrical mirror analyzer coupled with a quadrupole mass spectrometer. Energy distributions have been measured for oxygen, nitrogen, and inert gas ions incident with from 15 to 70 eV reflected from amorphous metal surfaces of several compositions. For ions of lighter atomic mass than the reflecting metal, reflected beams have peaked energy distributions; beams with the peak at 4-32 eV have been measured. The energy and mass dependences of the energy distributions as well as measurements of absolute flux, and angular distribution and divergence are reported. Applications of the neutral beams produced are described.

  7. Utilization of an intense beam of 800 MeV protons to prepare radionuclides

    SciTech Connect

    O'Brien, H.A.

    1988-01-01

    Since the early 1970's, a program has been underway at this institution to employ the excess proton beam emerging from the major experimental areas of the LAMPF accelerator to make a wide variety of radioactive nuclides. This paper presents a review of the targets irradiated, cross section data, and nuclide yield measurements. 32 refs., 1 figs., 8 tabs.

  8. Proton beam studies with a 1.25 MeV, cw radio frequency quadrupole linac

    SciTech Connect

    Bolme, G.O.; Hardek, T.W.; Hansborough, L.D.

    1998-12-31

    A high-current, cw linear accelerator has been proposed as a spallation neutron source driver for tritium production. Key features of this accelerator are high current (100 mA), low emittance-growth beam propagation, cw operation, high efficiency, and minimal maintenance downtime. A 268 MHz, cw radio frequency quadrupole (RFQ) LINAC section and klystrode based rf system were obtained from the Chalk River Laboratories and were previously installed at LANL to support systems development and advanced studies in support of cw, proton accelerators. A variation of the Low Energy Demonstration Accelerator (LEDA) proton injector, modified to operate at 50 keV, was mated to the RFQ and was operated to support advance developments for the Accelerator Production of Tritium (APT) program. High current, proton beam studies were completed which focused on the details of injector-RFQ integration, development of beam diagnostics, development of operations procedures, and personnel and equipment safety systems integration. This development led to acceleration of up to 100 mA proton beam.

  9. Thermoelectric Figures of Merit of Zn4Sb3 and Zrnisn-based Half-heusler Compounds Influenced by Mev Ion-beam Bombardments

    NASA Astrophysics Data System (ADS)

    Budak, S.; Guner, S.; Muntele, C. I.; Ila, D.

    Semiconducting β-Zn4Sb3 and ZrNiSn-based half-Heusler compound thin films with applications as thermoelectric (TE) materials were prepared using ion beam assisted deposition (IBAD). High-purity solid zinc (Zn) and antimony (Sb) were evaporated by electron beam to grow the β-Zn4Sb3 thin film while high-purity zirconium (Zr) powder and nickel (Ni) tin (Sn) powders were evaporated by electron beam to grow the ZrNiSn-based half-Heusler compound thin film. Rutherford backscattering spectrometry (RBS) was used to analyze the composition of the thin films. The grown thin films were subjected to 5 MeV Si ions bombardment for generation of nanostructures in the films. We measured the thermal conductivity, Seebeck coefficient, and electrical conductivity of these two systems before and after 5 MeV Si ions beam bombardment. The two material systems have been identified as promising TE materials for the application of thermal-to-electrical energy conversion, but the efficiency still limits their applications. The electronic energy deposited due to ionization in the track of MeV ion beam couldcause localized crystallization. The nanostructures produced by MeV ion beam can cause significant change in both the electrical and the thermal conductivity of thin films, thereby improving the efficiency. We used the 3ω-method (3rd harmonic) measurement system to measure the cross-plane thermal conductivity, the van der Pauw measurement system to measure the electrical conductivity, and the Seebeck-coefficient measurement system to measure the cross-plane Seebeck coefficient. The thermoelectric figures of merit of the two material systems were then derived by calculations using the measurement results. The MeV ion-beam bombardment was found to decrease the thermal conductivity of thin films and increase the efficiency of thermal-to-electrical energy conversion.

  10. Comparison of bactericidal efficiency of 7.5 MeV X-rays, gamma-rays, and 10 MeV e-beams

    NASA Astrophysics Data System (ADS)

    Song, Beom-Seok; Lee, Yunjong; Moon, Byeong-Geum; Go, Seon-Min; Park, Jong-Heum; Kim, Jae-Kyung; Jung, Koo; Kim, Dong-Ho; Ryu, Sang-Ryeol

    2016-08-01

    This study was performed to verify the feasibility of 7.5 MeV X-rays for food pasteurization through a comparison of the bactericidal efficiency with those of other sources for selected bacterial pathogens. No significant differences were observed between the overall bactericidal efficiency for beef-inoculated pathogens based on the uncertainty of the absorbed dose and variations in bacterial counts. This result supported that all three irradiation sources were effective for inactivation of food-borne bacteria and that 7.5 MeV X-rays may be used for food pasteurization.

  11. Thermal effects in high power cavities for photoneutralization of D{sup −} beams in future neutral beam injectors

    SciTech Connect

    Fiorucci, Donatella; Feng, Jiatai; Pichot, Mikhaël; Chaibi, Walid

    2015-04-08

    Photoneutralization may represent a key issue in the neutral beam injectors for future fusion reactors. In fact, photodetachment based neutralization combined with an energy recovery system increase the injector overall efficiency up to 60%. This is the SIPHORE injector concept in which photoneutralization is realized in a refolded cavity [1]. However, about 1 W of the several megaWatts intracavity power is absorbed by the mirrors coatings and gives rise to important thermoelastic distortions. This is expected to change the optical behavior of the mirrors and reduce the enhancement factor of the cavity. In this paper, we estimate these effects and we propose a thermal system to compensate it.

  12. Dosimetric verification of a commercial Monte Carlo treatment planning system (VMC++) for a 9 MeV electron beam

    SciTech Connect

    Schiapparelli, P.; Zefiro, D.; Taccini, G.

    2009-05-15

    The aim of this work was to evaluate the performance of the voxel-based Monte Carlo algorithm implemented in the commercial treatment planning system ONCENTRA MASTERPLAN for a 9 MeV electron beam produced by a linear accelerator Varian Clinac 2100 C/D. In order to realize an experimental verification of the computed data, three different groups of tests were planned. The first set was performed in a water phantom to investigate standard fields, custom inserts, and extended treatment distances. The second one concerned standard field, irregular entrance surface, and oblique incidence in a homogeneous PMMA phantom. The last group involved the introduction of inhomogeneities in a PMMA phantom to simulate high and low density materials such as bone and lung. Measurements in water were performed by means of cylindrical and plane-parallel ionization chambers, whereas measurements in PMMA were carried out by the use of radiochromic films. Point dose values were compared in terms of percentage difference, whereas the gamma index tool was used to perform the comparison between computed and measured dose profiles, considering different tolerances according to the test complexity. In the case of transverse scans, the agreement was searched in the plane formed by the intersection of beam axis and the profile (2D analysis), while for percentage depth dose curves, only the beam axis was explored (1D analysis). An excellent agreement was found for point dose evaluation in water (discrepancies smaller than 2%). Also the comparison between planned and measured dose profiles in homogeneous water and PMMA phantoms showed good results (agreement within 2%-2 mm). Profile evaluation in phantoms with internal inhomogeneities showed a good agreement in the case of ''lung'' insert, while in tests concerning a small ''bone'' inhomogeneity, a discrepancy was particularly evidenced in dose values on the beam axis. This is due to the inaccurate geometrical description of the phantom that is

  13. The radiation dosimetry of a quartz viewer irradiated with a 4.5 MeV proton beam

    NASA Astrophysics Data System (ADS)

    Ouyasathian, Kalong

    The present dissertation describes a procedure to measure the radiation dose received by an accelerator operator who uses a quartz viewer to locate an ion beam. This procedure consists of the following steps: (i) A solid-state gamma radiation detector was calibrated to determine its efficiency and its energy scale. (ii) The calibrated detector was used to measure the gamma energy spectrum obtained when bombarding the viewer with the ion beam. This measurement was normalized, that is, beam current and measurement duration were determined. (iii) Individual gamma energy lines were extracted from the gamma spectrum and the respective energies and emission rates were obtained. Energies were checked with known transitions in silicon and oxygen, to ensure correct identification. (iv) The Compton gamma energy spectrum generated by the primary gamma rays was determined using a Compton code. (v) Finally the charged-ion bremsstrahlung spectrum was obtained using the formalism of Alder et. al. In this dissertation several prospective contributors to the radiation dose have been checked and were found to be insignificant. They were: the radiation dose due to x-rays generated by Compton electrons and the radiation dose generated by electrons produced by collisions with the incident ions. With a proton energy of 4.5 MeV the eye dose equivalent was determined at 0 and 90 degrees to the proton beam. At 0 degree with a proton fluence rate of 8.9 x 1011 protons/s the dose was 8.7 x 10-3 rem/hr. At 90 degrees with a proton fluence rate of 1.1 x 1012 protons/s the dose was 8.1 x 10-3 rem/hr.

  14. Recent improvements to the DIII-D neutral beam instrumentation and control system

    SciTech Connect

    Kellman, D.H.; Hong, R.

    1997-11-01

    The DIII-D neutral beam (NB) instrumentation and control (I and C) system provides for operational control and synchronization of the eight DIII-D neutral beam injection systems, as well as for pertinent data acquisition and safety interlocking. Recently, improvements were made to the I and C system. With the replacement of the NB control computers, new signal interfacing was required to accommodate the elimination of physical operator panels, in favor of graphical user interface control pages on computer terminal screens. The program in the mode control (MC) programmable logic controller (PLC), which serves as a logic-processing interface between the NB control computers and system hardware, was modified to improve the availability of NB heating of DIII-D plasmas in the event that one or more individual beam systems suddenly become unavailable while preparing for a tokamak experimental shot sequences. An upgraded computer platform was adopted for the NB control system operator interface and new graphical user interface pages were developed to more efficiently display system status data. A failure mode of the armor tile infrared thermometers (pyrometers), which serve to terminate beam pulsing if beam shine-through overheats wall thermal shielding inside the DIII-D tokamak, was characterized such that impending failures can be detected and repairs effected to mitigate beam system down-time. The hardware that controls gas flow to the beamline neutralizer cells was upgraded to reduce susceptibility to electromagnetic interference (EMI), and interlocking was provided to terminate beam pulsing in the event of insufficient neutralizer gas flow. Motivation, implementation, and results of these improvements are presented.

  15. Use of radial self-field geometry for intense pulsed ion beam generation above 6 MeV on Hermes III.

    SciTech Connect

    Renk, Timothy Jerome; Harper-Slaboszewicz, Victor Jozef; Ginn, William Craig; Mikkelson, Kenneth A.; Schall, Michael; Cooper, Gary Wayne

    2012-12-01

    We investigate the generation and propagation of intense pulsed ion beams at the 6 MeV level and above using the Hermes III facility at Sandia National Laboratories. While high-power ion beams have previously been produced using Hermes III, we have conducted systematic studies of several ion diode geometries for the purpose of maximizing focused ion energy for a number of applications. A self-field axial-gap diode of the pinch reflex type and operated in positive polarity yielded beam power below predicted levels. This is ascribed both to power flow losses of unknown origin upstream of the diode load in Hermes positive polarity operation, and to anomalies in beam focusing in this configuration. A change to a radial self-field geometry and negative polarity operation resulted in greatly increased beam voltage (> 6 MeV) and estimated ion current. A comprehensive diagnostic set was developed to characterize beam performance, including both time-dependent and time-integrated measurements of local and total beam power. A substantial high-energy ion population was identified propagating in reverse direction, i.e. from the back side of the anode in the electron beam dump. While significant progress was made in increasing beam power, further improvements in assessing the beam focusing envelope will be required before ultimate ion generation efficiency with this geometry can be completely determined.

  16. A fully integrated 10 MeV electron beam sterilization system

    NASA Astrophysics Data System (ADS)

    Allen, J. T.; Calhoun, R.; Helm, J.; Kruger, S.; Lee, C.; Mendonsa, R.; Meyer, S.; Pageau, G.; Shaffer, H.; Whitham, K.; Williams, C. B.; Farrell, J. P.

    1995-02-01

    Societal pressure to check rising health care costs has resulted in demands for less expensive and more flexible methods to sterilize medical devices. This has generated renewed interest in electron beam sterilization because it offers fast turn-around time, high efficiency and improved reliability. The combination provides the opportunity for lower sterilization cost. The new Titan electron beam system in Denver, Colorado was designed and is operated as a 100% dedicated medical device sterilization process facility. It combines the electron accelerator, conveyor, safety, documentation and control subsystems into an integrated system used exclusively for the sterilization of disposable medical devices. System specifications and performance features are presented and plans for future development are discussed.

  17. Development of ion source with a washer gun for pulsed neutral beam injection.

    PubMed

    Asai, T; Yamaguchi, N; Kajiya, H; Takahashi, T; Imanaka, H; Takase, Y; Ono, Y; Sato, K N

    2008-06-01

    A new type of economical neutral beam source has been developed by using a single washer gun, pulsed operation, and a simple electrode system. We replaced the conventional hot filaments for arc-discharge-type plasma formation with a single stainless-steel washer gun, eliminating the entire dc power supply for the filaments and the cooling system for the electrodes. Our initial experiments revealed successful beam extraction up to 10 kV and 8.6 A, based on spatial profile measurements of density and temperature in the plasma source. The system also shows the potential to control the beam profile by controlling the plasma parameters in the ion accumulation chamber.

  18. Spectroscopic determination of the composition of a 50 kV hydrogen diagnostic neutral beam

    SciTech Connect

    Feng, X.; Nornberg, M. D. Den Hartog, D. J.; Oliva, S. P.; Craig, D.

    2016-11-15

    A grating spectrometer with an electron multiplying charge-coupled device camera is used to diagnose a 50 kV, 5 A, 20 ms hydrogen diagnostic neutral beam. The ion source density is determined from Stark broadened H{sub β} emission and the spectrum of Doppler-shifted H{sub α} emission is used to quantify the fraction of ions at full, half, and one-third beam energy under a variety of operating conditions including fueling gas pressure and arc discharge current. Beam current is optimized at low-density conditions in the ion source while the energy fractions are found to be steady over most operating conditions.

  19. Spectroscopic determination of the composition of a 50 kV hydrogen diagnostic neutral beam

    NASA Astrophysics Data System (ADS)

    Feng, X.; Nornberg, M. D.; Craig, D.; Den Hartog, D. J.; Oliva, S. P.

    2016-11-01

    A grating spectrometer with an electron multiplying charge-coupled device camera is used to diagnose a 50 kV, 5 A, 20 ms hydrogen diagnostic neutral beam. The ion source density is determined from Stark broadened Hβ emission and the spectrum of Doppler-shifted Hα emission is used to quantify the fraction of ions at full, half, and one-third beam energy under a variety of operating conditions including fueling gas pressure and arc discharge current. Beam current is optimized at low-density conditions in the ion source while the energy fractions are found to be steady over most operating conditions.

  20. Calculating Variations in Biological Effectiveness for a 62 MeV Proton Beam

    PubMed Central

    Carante, Mario Pietro; Ballarini, Francesca

    2016-01-01

    A biophysical model of radiation-induced cell death and chromosome aberrations [called BIophysical ANalysis of Cell death and chromosome Aberrations (BIANCA)] was further developed and applied to therapeutic protons. The model assumes a pivotal role of DNA cluster damage, which can lead to clonogenic cell death following three main steps: (i) a DNA “cluster lesion” (CL) produces two independent chromosome fragments; (ii) fragment mis-rejoining within a threshold distance d gives rise to chromosome aberrations; (iii) certain aberration types (dicentrics, rings, and large deletions) lead to clonogenic inactivation. The yield of CLs and the probability, f, that a chromosome fragment remains un-rejoined even if other fragment(s) are present within d, were adjustable parameters. The model, implemented as a MC code providing simulated dose–responses directly comparable with experimental data, was applied to pristine and modulated Bragg peaks of the proton beam used to treat eye melanoma at INFN-LNS in Catania, Italy. Experimental survival curves for AG01522 cells exposed to the Catania beam were reproduced, supporting the model assumptions. Furthermore, cell death and chromosome aberrations at different depths along a spread-out Bragg peak (SOBP) dose profile were predicted. Both endpoints showed an increase along the plateau, and high levels of damage were found also beyond the distal dose fall-off, due to low-energy protons. Cell death and chromosome aberrations were also predicted for V79 cells, in the same irradiation scenario as that used for AG01522 cells. In line with other studies, this work indicated that assuming a constant relative biological effectiveness (RBE) along a proton SOBP may be sub-optimal. Furthermore, it provided qualitative and quantitative evaluations of the dependence of the beam effectiveness on the considered endpoint and dose. More generally, this work represents an example of therapeutic beam characterization avoiding the use of

  1. Neutral atomic oxygen beam produced by ion charge exchange for Low Earth Orbital (LEO) simulation

    NASA Technical Reports Server (NTRS)

    Banks, Bruce; Rutledge, Sharon; Brdar, Marko; Olen, Carl; Stidham, Curt

    1987-01-01

    A low energy neutral atomic oxygen beam system was designed and is currently being assembled at the Lewis Research Center. The system utilizes a 15 cm diameter Kaufman ion source to produce positive oxygen ions which are charge exchange neutralized to produce low energy (variable from 5 to 150 eV) oxygen atoms at a flux simulating real time low Earth orbital conditions. An electromagnet is used to direct only the singly charged oxygen ions from the ion source into the charge exchange cell. A retarding potential grid is used to slow down the oxygen ions to desired energies prior to their charge exchange. Cryogenically cooled diatomic oxygen gas in the charge exchange cell is then used to transfer charge to the oxygen ions to produce a neutral atomic oxygen beam. Remaining non-charge exchanged oxygen ions are then swept from the beam by electromagnetic or electrostatic deflection depending upon the desired experiment configuration. The resulting neutral oxygen beam of 5 to 10 cm in diameter impinges upon target materials within a sample holder fixture that can also provide for simultaneous heating and UV exposure during the atomic oxygen bombardment.

  2. Improved numerical calculation of the generation of a neutral beam by charge transfer between chlorine ions/neutrals and a graphite surface

    NASA Astrophysics Data System (ADS)

    Kubota, Tomohiro; Watanabe, Naoki; Ohtsuka, Shingo; Iwasaki, Takuya; Ono, Kohei; Iriye, Yasuroh; Samukawa, Seiji

    2014-11-01

    The charge transfer process between chlorine particles (ions or neutrals) and a graphite surface on collision was investigated by using a highly stable numerical simulator based on time-dependent density functional theory to understand the generation mechanism of a high-efficiency neutral beam developed by Samukawa et al (2001 Japan. J. Appl. Phys. 40 L779). A straightforward calculation was achieved by adopting a large enough unit cell. The dependence of the neutralization efficiency on the incident energy of the particle was investigated, and the trend of the experimental result was reproduced. It was also found that doping the electrons and holes into graphite could change the charge transfer process and neutralization probability. This result suggests that it is possible to develop a neutral beam source that has high neutralization efficiency for both positive and negative ions.

  3. Initial Off-Axis Neutral Beam Checkout and Physics Experiments on DIII-D

    NASA Astrophysics Data System (ADS)

    van Zeeland, M. A.; Ferron, J. R.; Hyatt, A. W.; Murphy, C. J.; Petty, C. C.; Prater, R.; Scoville, J. T.; Heidbrink, W. W.; Muscatello, C. M.; Park, J. M.; Murakami, M.; Pace, D. C.; Holcomb, C. T.; Grierson, B. A.; Tobias, B. J.; Solomon, W. M.; Moyer, R. A.

    2011-10-01

    Two of the eight neutral beam sources on DIII-D have been modified to allow vertical steering, with the injection angle varying from horizontal to downward at an angle of 16.5 degrees for off-axis deposition. Initial experiments to assess the basic beam functionality, geometry, and confinement were carried out. Dα images of beam into gas and plasma yield beam neutral profiles and are key in assessing beam shape and clipping. Neutron and fast-ion Dα (FIDA) diagnostics verify classical behavior of the off-axis beam ions in MHD-quiescent conditions. An initial physics experiment takes advantage of the downward steered beams to vary the fast-ion gradient ∇βf from centrally peaked to hollow. Systematic scans determine the stability and impact of reversed shear Alfvén eigenmodes and toroidal Alfvén eigenmodes as a function of ∇βf . Supported by US DOE under DE-FC02-04ER54698, SC-G903402, DE-AC05-00OR22725, DE-AC05-06OR23100, DE-AC52-07NA27344, DE-AC02-09CH11466, & DE-FG02-07ER54917.

  4. Design, fabrication and operation of the mechanical systems for the Neutral Beam Engineering Test Facility

    SciTech Connect

    Paterson, J.A.; Biagi, L.A.; Fong, M.; Koehler, G.W.; Low, W.; Purgalis, P.; Wells, R.P.

    1983-12-01

    The Neutral Beam Engineering Test Facility (NBETF) at Lawrence Berkeley Laboratory (LBL) is a National Test Facility used to develop long pulse Neutral Beam Sources. The Facility will test sources up to 120 keV, 50 A, with 30 s beam-on times with a 10% duty factor. For this application, an actively cooled beam dump is required and one has been constructed capable of dissipating a wide range of power density profiles. The flexibility of the design is achieved by utilizing a standard modular panel design which is incorporated into a moveable support structure comprised of eight separately controllable manipulator assemblies. A unique neutralizer design has been installed into the NBETF beamline. This is a gun-drilled moveable brazed assembly which provides continuous armoring of the beamline near the source. The unit penetrates the source mounting valve during operation and retracts to permit the valve to close as needed. The beamline is also equpped with many beam scraper plates of differing detail design and dissipation capabilities.

  5. Damage during SiO2 Etching by Low-Angle Forward Reflected Neutral Beam

    NASA Astrophysics Data System (ADS)

    Lee, Dohaing; Chung, Minjae; Park, Sangduk; Yeom, Geunyoung

    2002-12-01

    In this study, energetic reactive radical beams were formed with SF6 using a low-angle forward reflected neutral beam technique and the etch properties of SiO2 and possible damage induced by the radical beam were investigated. The results showed that when SiO2 was etched with the energetic reactive radical beams generated with SF6, SiO2 etch rates higher than 22 nm/min could be obtained. Also, when the etch damage was studied in terms of the capacitance-voltage (C-V) and current-voltage (I-V) characteristics of metal-nitride-oxide-silicon (MNOS) and metal-oxide-silicon (MOS) devices exposed to the radical beams, nearly no etch damage could be found.

  6. Design of Main Control Console Software in EAST Neutral Beam Injector's Control System for the First Beam Line

    NASA Astrophysics Data System (ADS)

    Wu, De-Yun; Hu, Chun-Dong; Sheng, Peng; Zhao, Yuan-Zhe; Zhang, Xiao-Dan; Cui, Qing-Long

    2013-10-01

    Neutral beam injector is one of the main plasma heating and plasma current driving methods for experimental advanced superconducting tokomaks (EAST). In order to realize visual operation of EAST neutral beam injector's control system (NBICS), main control console (MCC) is developed to work as the human-machine interface between the NBICS and physical operator. It can meet the requirements of visual control of NBICS by providing a user graphic interface. With the specific algorithms, the setup of power supply sequence is relatively independent and simple. Displaying the real-time feedback of the subsystems provides a reference for operators to monitor the status of the system. The MCC software runs on a Windows system and uses C++ language code while using client/server (C/S) mode, multithreading and cyclic redundancy check technology. The experimental results have proved that MCC provides a stability and reliability operation of NBICS and works as an effective man-machine interface at the same time.

  7. Reducing shield thickness and backscattered radiation using a multilayered shield for 6–10 MeV electron beams.

    PubMed

    Butson, Martin; Chen, Tom; Rattanavoang, Somkhit; Hellyer, James; Gray, Alison; Nelson, Vinod; Short, Richard; Rajapakse, Satya; Lee, James; Fogarty, Gerald; Izard, Michael; Hill, Robin

    2015-12-01

    Intraoral and external electron shields used in radiotherapy are designed to minimize radiation exposure to non-treatment tissue. Sites where shields are used include but are not limited to, the treatment of lips, cheeks and ears whilst shielding the underlying oral cavity, tongue, gingival or temporal region. A commonly known and published effect, concerns the enhancement in dose that can occur on the beam side on an electron shield caused by an increase in electron backscatter radiation. In this work a lead shield has been designed incorporating copper, aluminium and wax in a step down filter arrangement to minimise backscatter whilst minimizing overall shield thickness for better clinical setup and ease of use. For electron beams ranging from 6 to 10 MeV, a standard shield design of 4 mm lead, 0.6 mm copper, 1.0 mm aluminium and 1.5 mm wax (3.1 mm added filtration, 7.1 mm total thickness) provided adequate backscatter and transmission reduction to match a standard 4.5 mm lead and 10 mm wax (total thickness 14.5 mm) electron shield. Dose enhancement values of no more than 10 % were measured utilising this shield design with a 50 % reduction in shield thickness. The thinner shield will not only allow easier patient set up but should be tolerated better by patients when mucosal reactions occur as they place less physical pressure on these sites during treatment due to their smaller size.

  8. A thin column of dense plasma for space-charge neutralization of intense ion beams

    NASA Astrophysics Data System (ADS)

    Roy, P. K.; Seidl, P. A.; Anders, A.; Barnard, J. J.; Bieniosek, F. M.; Friedman, A.; Gilson, E. P.; Greenway, W.; Sefkow, A. B.; Jung, J. Y.; Leitner, M.; Lidia, S. M.; Logan, B. G.; Waldron, W. L.; Welch, D. R.

    2008-11-01

    Typical ion driven warm dense matter experiment requires a plasma density of 10^14/cm^3 to meet the challenge of np>nb, where np, and nb are the number densities of plasma and beam, respectively. Plasma electrons neutralize the space charge of an ion beam to allow a small spot of about 1-mm radius. In order to provide np>nb for initial warm, dense matter experiments, four cathodic arc plasma sources have been fabricated, and the aluminum plasma is focused in a focusing solenoid (8T field). A plasma probe with 37 collectors was developed to measure the radial plasma profile inside the solenoid. Results show that the plasma forms a thin column of diameter ˜7mm along the solenoid axis. The magnetic mirror effect, plasma condensation, and the deformation of the magnetic field due to eddy currents are under investigation. Data on plasma parameters and ion beam neutralization will be presented.

  9. Summary of the status of negative-ion-based neutral beams

    SciTech Connect

    Cooper, W.S.

    1983-01-01

    Negative-ion-based neutral beam systems can perform multiple functions for fusion reactors, such as heating, current drive in tokamak reactors, and establishing and maintaining potential barriers in tandem mirror reactors. Practical systems operating continuously at the 200 keV, 1 MW level can be built using present-day technology. Ion sources have been demonstrated that produce D/sup -/ beams with <5% electron content, and that operate at linear current densities that are within a factor of 2 of what conservatively designed accelerator/transport structures can handle. Concepts are in hand for transporting the negative ion beam through a neutron maze before neutralization, thus permitting a radiation-hardened beamline. With an advanced laser photoneutralizer, overall system power efficiencies of 70% should be possible. A national program is being planned to achieve the goal of application of 475 keV systems on a mirror ETR in 1994.

  10. Instrumentation developments for production and characterisation of Inverse Compton Scattering X-rays and first results with a 17 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Chauchat, A. S.; Le Flanchec, V.; Nègre, J. P.; Binet, A.; Balleyguier, P.; Brasile, J. P.; Ortega, J. M.

    2010-10-01

    An X-ray Compton source is under development at the ELSA facility. The electron beam coming from the ELSA linear accelerator interacts with a laser beam to generate an X-ray flux in the direction of the electron beam. With a 17 MeV electron beam and a 532 nm laser, the resulting X-ray maximal energy is around 11 keV. The beams visualization at the interaction point is achieved via an aluminum retractable bevel-edge with an OTR surface on one side and a slightly roughened surface on the other. Thanks to an optical beamsplitter, beam images are both transmitted to a CCD camera and to a streak camera to manage the spatial and temporal overlap of the bunches. Careful beam management and electron background noise minimization were both required to observe the first Inverse Compton Scattering X-ray profile of this source on radio-luminescent imaging plates.

  11. Characteristics of electron beams from a new 25-MeV linear accelerator

    SciTech Connect

    O'Brien, P.; Michaels, H.B.; Aldrich, J.E.; Andrew, J.W.

    1985-11-01

    Clinically useful electron fields are produced on the Atomic Energy of Canada, Limited Therac 25 linear accelerator by computer-controlled scanning of the electron beam. Measurements were made to determine the properties of these electron fields. Central axis percentage depth dose and bremsstrahlung background were compared for these fields and for the fields from selected machines that use scattering foils. Dose calibrations were made in both water and polystyrene using the American Association of Physicists in Medicine Task Group 21 protocol. Measurements were made to determine the relative output factors, virtual source position, and the attenuation of the electron fields by lead.

  12. Characteristics of electron beams from a new 25-MeV linear accelerator.

    PubMed

    O'Brien, P; Michaels, H B; Aldrich, J E; Andrew, J W

    1985-01-01

    Clinically useful electron fields are produced on the Atomic Energy of Canada, Limited Therac 25 linear accelerator by computer-controlled scanning of the electron beam. Measurements were made to determine the properties of these electron fields. Central axis percentage depth dose and bremsstrahlung background were compared for these fields and for the fields from selected machines that use scattering foils. Dose calibrations were made in both water and polystyrene using the American Association of Physicists in Medicine Task Group 21 protocol. Measurements were made to determine the relative output factors, virtual source position, and the attenuation of the electron fields by lead.

  13. Measurement of a 200 MeV proton beam using a polyurethane dosimeter

    NASA Astrophysics Data System (ADS)

    Heard, Malcolm; Adamovics, John; Ibbott, Geoffrey

    2006-12-01

    PRESAGETM (Heuris Pharma LLC, Skillman, NJ) is a three-dimensional polyurethane dosimeter containing a leuco dye that generates a color change when irradiated. The dosimeter is solid and does not require a container to maintain its shape. The dosimeter is transparent before irradiation and the maximum absorbance of the leuco dye occurs at 633 nm which is compatible with the OCT-OPUSTM laser CT scanner (MGS Research, Inc., Madison, CT). The purpose of this study was to investigate the response of PRESAGETM to proton beam radiotherapy.

  14. Nonlinear theory of electron neutralization waves in ions beams with dissipation

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1974-01-01

    An analytical theory of nonlinear neutralization waves generated by injection of electrons from a grid in the direction of a homogeneous ion beam of uniform velocity and infinite extension is presented. The electrons are assumed to interact with the ions through the self-consistent space charge field and by strong collective interactions, while diffusion in the pressure gradient is disregarded (zero-temperature approximation). The associated nonlinear boundary-value problem is solved in closed form by means of a von Mises transformation. It is shown that the electron gas moves into the ion space in the form of a discontinuous neutralization wave, which exhibits a periodic field structure (incomplete neutralization). This periodic wave structure is damped out by intercomponent momentum transfer - i.e., after a few relaxation lengths a quasi-neutral plasma results.

  15. A comparative study on low-energy ion beam and neutralized beam modifications of naked DNA and biological effect on mutation

    NASA Astrophysics Data System (ADS)

    Sarapirom, S.; Thongkumkoon, P.; Prakrajang, K.; Anuntalabhochai, S.; Yu, L. D.

    2012-02-01

    DNA conformation change or damage induced by low-energy ion irradiation has been of great interest owing to research developments in ion beam biotechnology and ion beam application in biomedicine. Mechanisms involved in the induction of DNA damage may account for effect from implanting ion charge. In order to check this effect, we used both ion beam and neutralized beam at keV energy to bombard naked DNA. Argon or nitrogen ion beam was generated and extracted from a radiofrequency (RF) ion source and neutralized by microwave-driven plasma in the beam path. Plasmid DNA pGFP samples were irradiated with the ion or neutralized beam in vacuum, followed by gel electrophoresis to observe changes in the DNA conformations. It was revealed that the ion charge played a certain role in inducing DNA conformation change. The subsequent DNA transfer into bacteria Escherichia coli ( E. coli) for mutation analysis indicated that the charged ion beam induced DNA change had high potential in mutation induction while neutralized beam did not. The intrinsic reason was attributed to additional DNA deformation and contortion caused by ion charge exchange effect so that the ion beam induced DNA damage could hardly be completely repaired, whereas the neutralized beam induced DNA change could be more easily recoverable owing to absence of the additional DNA deformation and contortion.

  16. The measurement of neutral beam thermal profiles on `V`-shaped calorimeters

    SciTech Connect

    Kamperschroer, J.H.; Lagin, L.J.; Silber, K.

    1995-12-31

    It is customary in high power neutral beam systems to use a V-shaped calorimeter to stop and measure the beam. With proper instrumentation, it is possible to determine both the neutral beam power and divergence. By utilizing a near-grazing angle of incidence, the area over which the beam is in contact with the surface is increased, thereby decreasing the power density over the case of normal incidence. Thermocouples on the back of the calorimeter, in conjunction with real time fitting algorithms, are used to deduce the divergence from the thermal profile. This measurement implicitly assumes that the measured profile corresponds to that of the incident beam. It is shown that such is not the case. Energetic particle reflection at near-grazing angle causes the thermal profile on the calorimeter to be more peaked than the incident distribution. The implications of this on the non-linear multiple regression technique of determining the divergence are discussed. With the aid of a reflection model, developed and applied to the beam from a typical TFTR ion source, it is shown that a peaked power density can be modelled. Neural networks are being studied as a means of supplanting the older regression technique of measuring divergence. Y-direction divergences have been successfully derived using a one-dimensional neural network.

  17. Ion transport studies on the PLT tokamak during neutral beam injection

    SciTech Connect

    Suckewer, S.; Cavallo, A.; Cohen, S.; Daughney, C.; Denne, B.; Hinnov, E.; Hosea, J.; Hulse, R.; Hwang, D.; Schilling, G.

    1983-12-01

    Radial transport of ions during co- and counter-neutral beam heating in the PLT tokamak has been studied, using molybdenum and scandium ions as tracer elements. The time evolution of the radial profiles of several ionization stages of both elements, injected by laser blowoff during the neutral beam heating, were measured under three significantly different beam-plasma combinations. No noticeable differences in the radial profiles attributable to the beam direction were observed. However, a given injected amount resulted in considerably larger interior concentrations of the tracer element in the counter-beam heating cases, suggesting larger penetration of the plasma periphery. Computer simulation with the MIST code suggests a net inward drift of the order 10/sup 3/ cm/sec superposed to a diffusion coefficient of the order 10/sup 4/ cm/sup 2//sec for both scandium and molybdenum ions. Injection of larger amounts of the tracer element, sufficient to cause measurable central electron temperature changes, resulted in dramatic changes in ion-state distributions, making some appear peaked in the center while others disappeared. This effect could be produced with both co- and counter-beam heating, but with lesser amounts in the latter case. It is interpreted as rearrangement of the ionization balance, rather than any preferential accumulation of the injected element.

  18. Predictive Calculation of Neutral Beam Heating Plasmas in EAST Tokamak by NUBEAM Code for Certain Parameter Ranges

    NASA Astrophysics Data System (ADS)

    Ni, Qionglin; Fan, Tieshuan; Zhang, Xing; Zhang, Cheng; Ren, Qilong; Hu, Chundong

    2010-12-01

    A predictive calculation is carried out for neutral beam heating of fusion plasmas in EAST by using NUBEAM code under certain plasma conditions. Results calculated are analyzed for different plasma parameters. Relations between major plasma parameters, such as density and temperature, are obtained and key physical processes in the neutral beam heating, including beam power deposition, trapped fraction, heating efficiency, and power loss, are simulated. Other physical processes, such as current-drive, toroidal rotation and neutron emission, are also discussed.

  19. DISSOLVED OXYGEN REDUCTION IN THE DIII-D NEUTRAL BEAM ION SOURCE COOLING SYSTEM

    SciTech Connect

    YIP,H; BUSATH,J; HARRISON,S

    2003-10-01

    OAK-B135 Neutral beam ion sources (NBIS) are critical components for the neutral beam injection system supporting the DIII-D tokamak. The NBIS must be cooled with 3028 {ell}/m (800 gpm) of de-ionized and de-oxygenated water to protect the sources from overheating and failure. These ions sources are currently irreplaceable. Since the water cooled molybdenum components will oxidize in water almost instantaneously in the presence of dissolved oxygen (DO), de-oxygenation is extremely important in the NBIS water system. Under normal beam operation the DO level is kept below 5 ppb. However, during weeknights and weekends when neutral beam is not in operation, the average DO level is maintained below 10 ppb by periodic circulation with a 74.6 kW (100 hp) pump, which consumes significant power. Experimental data indicated evidence of continuous oxygen diffusion through non-metallic hoses in the proximity of the NBIS. Because of the intermittent flow of the cooling water, the DO concentration at the ion source(s) could be even higher than measured downstream, and hence the concern of significant localized oxidation/corrosion. A new 3.73 kW (5 hp) auxiliary system, installed in the summer of 2003, is designed to significantly reduce the peak and the time-average DO levels in the water system and to consume only a fraction of the power.

  20. 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.

  1. LET dependence of the response of a PTW-60019 microDiamond detector in a 62MeV proton beam.

    PubMed

    Rossomme, S; Denis, J M; Souris, K; Delor, A; Bartier, F; Dumont, D; Vynckier, S; Palmans, H

    2016-09-01

    This study was initiated following conclusions from earlier experimental work, performed in a low-energy carbon ion beam, indicating a significant LET dependence of the response of a PTW-60019 microDiamond detector. The purpose of this paper is to present a comparison between the response of the same PTW-60019 microDiamond detector and an IBA Roos-type ionization chamber as a function of depth in a 62MeV proton beam. Even though proton beams are considered as low linear energy transfer (LET) beams, the LET value increases slightly in the Bragg peak region. Contrary to the observations made in the carbon ion beam, in the 62MeV proton beam good agreement is found between both detectors in both the plateau and the distal edge region. No significant LET dependent response of the PTW-60019 microDiamond detector is observed consistent with other findings for proton beams in the literature, despite this particular detector exhibiting a substantial LET dependence in a carbon ion beam. Copyright © 2016 Associazione Italiana di Fisica Medica. All rights reserved.

  2. An in-beam PET system for monitoring ion-beam therapy: test on phantoms using clinical 62 MeV protons

    NASA Astrophysics Data System (ADS)

    Camarlinghi, N.; Sportelli, G.; Battistoni, G.; Belcari, N.; Cecchetti, M.; Cirrone, G. A. P.; Cuttone, G.; Ferretti, S.; Kraan, A.; Retico, A.; Romano, F.; Sala, P.; Straub, K.; Tramontana, A.; Del Guerra, A.; Rosso, V.

    2014-04-01

    Ion therapy allows the delivery of highly conformal dose taking advantage of the sharp depth-dose distribution at the Bragg-peak. However, patient positioning errors and anatomical uncertainties can cause dose distortions. To exploit the full potential of ion therapy, an accurate monitoring system of the ion range is needed. Among the proposed methods to monitor the ion range, Positron Emission Tomography (PET) has proven to be the most mature technique, allowing to reconstruct the β+ activity generated in the patient by the nuclear interaction of the ions, that can be acquired during or after the treatment. Taking advantages of the spatial correlation between positron emitters created along the ions path and the dose distribution, it is possible to reconstruct the ion range. Due to the high single rates generated during the beam extraction, the acquisition of the β+ activity is typically performed after the irradiation (cyclotron) or in between the synchrotron spills. Indeed the single photon rate can be one or more orders of magnitude higher than normal for cyclotron. Therefore, acquiring the activity during the beam irradiation requires a detector with a very short dead time. In this work, the DoPET detector, capable of sustaining the high event rate generated during the cyclotron irradiation, is presented. The capability of the system to acquire data during and after the irradiation will be demonstrated by showing the reconstructed activity for different PMMA irradiations performed using clinical dose rates and the 62 MeV proton beam at the CATANA-LNS-INFN. The reconstructed activity widths will be compared with the results obtained by simulating the proton beam interaction with the FLUKA Monte Carlo. The presented data are in good agreement with the FLUKA Monte Carlo.

  3. Neutral Beam Injection System for the C-2W Field Reversed Configuration Experiment

    NASA Astrophysics Data System (ADS)

    Dunaevsky, Alexander; Ivanov, Alexander; Kolmogorov, Vyacheslav; Smirnov, Artem; Korepanov, Sergey; Binderbauer, Michl; TAE Team; BINP Team

    2016-10-01

    C-2U Field-Reversed Configuration (FRC) experiment proved substantial reduction in turbulence-driven losses via tangential neutral beam injection (NBI) coupled with electrically biased plasma guns at the plasma ends. Under such conditions, highly reproducible, advanced beam-driven FRCs were produced and sustained for times significantly longer (more than 5 ms) than all characteristic plasma decay times without beams. To further improve FRC sustainment and demonstrate the FRC ramp-up, the C-2U experimental device is undergoing a major upgrade. The upgrade, C-2W, will have a new NBI system producing a record total hydrogen beam power of 20 + MW in a 30ms pulse. The NBI system consists of eight positive-ion based injectors featuring flexible, modular design. Four out of eight NBI injectors have a capability to switch the beam energy during a shot from the initial 15 keV to 40 keV at a constant beam current. This feature allows to increase the beam energy and thereby optimize the beam-plasma coupling during the magnetic field ramp up. This presentation provides an overview of the C-2W NBI system, including the design of the switchable energy injectors, layout of the power supply system, and results of the prototype testing.

  4. Impact of diagnostic neutral beam optimization on active spectroscopy in MST

    NASA Astrophysics Data System (ADS)

    Feng, Xiande; Nornberg, Mark. D.; den Hartog, Daniel. J.; Oliva, Steven. P.; Craig, Darren; Univ of Wisconsin, Madison Team; Wheaton College, IL Collaboration

    2016-10-01

    The hydrogen diagnostic neutral beam on MST provides local measurements of impurity ion emission through charge exchange recombination spectroscopy (CHERS) and of core-localized magnetic field through the motional Stark effect (MSE). The beam has been optimized to operate at 50kV, 4A steady beam current with 20ms beam pulse and 75% primary energy ion fraction. It's achieved by tuning the beam voltage, arc current, fuel line pressure, arc and high voltage module timing, and the magnetic isolation field. Electron density measurements in the ion source revealed that ion extraction is maximized under low density conditions which are thought to affect the shape of the ion sheath at the extraction grid. The sheath may be transitioning from a planar or convex shape at high density to one which is concave which helps focus the ion trajectories and produce higher beam current. With the improvements in beam operation, the CHERS signal is expected to increase by 20%-30%, and the Stark broadening is expected to increase by 10%. These signal increases will help resolve convolved fine-structure components in both analyses. Beam voltage ripple is also measured to better quantify the accuracy of spectral MSE and CHERS measurement. This work is supported by the U.S. DOE.

  5. A Parasitic Effect in Neutral Particle Diagnostic Using a Helium Probing Beam

    NASA Astrophysics Data System (ADS)

    Tobita, Kenji; Kusama, Yoshinori; Itoh, Takao; Nemoto, Masahiro; Takeuchi, Hiroshi; Tsukahara, Yoshimitsu

    1990-04-01

    This paper describes the characteristic and the physical picture of a parasitic disturbance, which can occur because of the drift motion of probing beam ions trapped at the plasma edge, in active neutral particle measurements for magnetically confined fusion devices. In the JT-60 experiments, the disturbance is observed under the condition in which a neutral particle analyzer views the high recycling region, i.e., the divertor, and the occurrence of the parasitic effect is substantially dependent on the safety factor at the plasma boundary. Also discussed are the validity of our interpretation and some measures for avoiding the disturbance.

  6. Determination of electron beam output factors for a 20-MeV linear accelerator

    SciTech Connect

    Mills, M.D.; Hogstrom, K.R.; Fields, R.S.

    1985-07-01

    The demands of a busy clinic require that basic machine calculations be performed as accurately, rapidly, and simply as possible. For the electron beam of the Therac 20 Saturne linear accelerator, a method suitable for a programmable calculator is described to predict the dose output from the measurement of selected fields. One-dimensional output factors were measured; these are defined as output factors of rectangular fields where one side is always equal to the side of the square reference field. The output of an arbitrary rectangular field X, Y is given by the product of the output factors OF(X,Y) = OF(X,10) x OF(10,Y), where 10 is the side of the square reference field. The measured data indicate that the output of very large rectangular and square fields is underestimated using this method for the lower energies. A correction factor of the form CF = C x ((X-10)(Y-10)/Vertical Bar(X-10)(Y-10)Vertical Bar/sup 1//sup ///sup 2/) results in agreement with measured data to within 1.5% for all energies.

  7. Determination of electron beam output factors for a 20-MeV linear accelerator.

    PubMed

    Mills, M D; Hogstrom, K R; Fields, R S

    1985-01-01

    The demands of a busy clinic require that basic machine calculations be performed as accurately, rapidly, and simply as possible. For the electron beam of the Therac 20 Saturne linear accelerator, a method suitable for a programmable calculator is described to predict the dose output from the measurement of selected fields. One-dimensional output factors were measured; these are defined as output factors of rectangular fields where one side is always equal to the side of the square reference field. The output of an arbitrary rectangular field X, Y is given by the product of the output factors OF(X,Y) = OF(X,10) X OF(10,Y), where 10 is the side of the square reference field. The measured data indicate that the output of very large rectangular and square fields is underestimated using this method for the lower energies. A correction factor of the form CF = C X [(X - 10)(Y - 10)/(X - 10)(Y - 10) 1/2] results in agreement with measured data to within 1.5% for all energies.

  8. Fragmentation of 200 and 244 MEV/u Carbon Beams in Thick Tissue-Like Absorbers

    NASA Technical Reports Server (NTRS)

    Golovchenko, A. N.; Skvarc, J.; Ilic, R.; Sihver, L.; Bamblevski, V. P.; Tretyakova, S. P.; Schardt, D.; Tripathi, R. K.; Wilson, J. W.; Bimbot, R.

    1999-01-01

    Stacks consisting of thin CR-39 sheets sandwiched between thick lucite and water absorbers were perpendicularly bombarded by C-12 ions at 200 and 244 MeV/u. Track radius distributions representing the charge composition of the fragmented beams were automatically measured by a particle track analysis system. After analysis of the nuclear charge distributions, the total charge removal cross-sections and elemental production cross-sections of fragments with atomic numbers from 5 to 3, were obtained down to the lower energies (approx. 50 and 100 MeV/u, respectively). It has been found that the measured total charge removal cross-section agrees with theoretical predictions within approx. 10% and very well with previous experiments in corresponding energy regions. Two model calculations for production of B fragment are in good agreement with our measured data while a third model overestimates it by approx. 12%. Theoretical cross-sections for Be and Li fragments differ strongly among the different models and from measured values.

  9. Stochastic Orbit Loss of Neutral Beam Ions From NSTX Due to Toroidal Alfven Eigenmode Avalanches

    SciTech Connect

    Darrow, D S; Fredrickson, E D; Gorelenkov, N N; Gorelenkova, M; Kubota, S; Medley, S S; Podesta, M; Shi, L

    2012-07-11

    Short toroidal Alfven eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and sometimes a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions occurs. When beam ion orbits are followed with a guiding center code that incorporates plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are similar to those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary.

  10. Oxide degradation effects in dry patterning of resist using neutral oxygen beams

    SciTech Connect

    Mlynko, W.E.; Kasi, S.R.; Manos, D.

    1992-07-01

    Novel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, after MOSFET gate oxide quality, impacting device performance and reliability. We have studied this processing related device integrity issue by subjecting polysilicon gas MOS structures to exposure treatments similar to those used in resist patterning using low energy oxygen beams. Electrical C-V characterization shows a significant increase in the oxide trapped charge and interface state density upon low energy exposure. I-V and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25-V to 0.5-V negative flatband shifts can be partially annealed by the carrier injection. This could be due to positive charge annihilation or electron trapping, or some combination of both. Physical and analysis of patterned resist layers and electrical characterization data of MOS structures exposed to different neutral beam processing environments and following thermal annealing treatments is presented.

  11. Oxide degradation effects in dry patterning of resist using neutral oxygen beams

    SciTech Connect

    Mlynko, W.E.; Kasi, S.R. ); Manos, D. . Plasma Physics Lab.)

    1992-01-01

    Novel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, after MOSFET gate oxide quality, impacting device performance and reliability. We have studied this processing related device integrity issue by subjecting polysilicon gas MOS structures to exposure treatments similar to those used in resist patterning using low energy oxygen beams. Electrical C-V characterization shows a significant increase in the oxide trapped charge and interface state density upon low energy exposure. I-V and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25-V to 0.5-V negative flatband shifts can be partially annealed by the carrier injection. This could be due to positive charge annihilation or electron trapping, or some combination of both. Physical and analysis of patterned resist layers and electrical characterization data of MOS structures exposed to different neutral beam processing environments and following thermal annealing treatments is presented.

  12. Simulation And Design Of A Reflection Magnet For The EAST Neutral Beam System

    SciTech Connect

    Zhen Liangli; Dong Huchun

    2011-09-26

    The simulation and design of a reflection magnet to be installed in the Experimental Advanced Superconducting Tokamak (EAST) neutral beam injection system are reported. A parametric design and simulation for the reflection magnet was carried out. For a deuterium beam with 42 cm as the bending radius, the intensity of reflection magnet field is about 1376 Gs at the energy of 80 keV. In order to determine position of the ion dump and the surface power load, a particle simulation with Monte Carlo was developed to study ion trajectories. In addition, the louver design is introduced.

  13. Fabrication of OSOS cells by neutral ion beam sputtering. [Oxide Semiconductor On Silicon solar cells

    NASA Technical Reports Server (NTRS)

    Burk, D. E.; Dubow, J. B.; Sites, J. R.

    1976-01-01

    Oxide semiconductor on silicon (OSOS) solar cells have been fabricated from various indium tin oxide (In2O3)x(SnO2)1-x compositions sputtered onto p-type single crystal silicon substrates with a neutralized argon ion beam. High temperature processing or annealing was not required. The highest efficiency was achieved with x = 0.91 and was 12 percent. The cells are environmentally rugged, chemically stable, and show promise for still higher efficiencies. Moreover, the ion beam sputtering fabrication technique is amenable to low cost, continuous processing.

  14. Heating neutral beams for ITER: negative ion sources to tune fusion plasmas

    NASA Astrophysics Data System (ADS)

    Singh, M. J.; Boilson, D.; Polevoi, A. R.; Oikawa, Toshihiro; Mitteau, Raphael

    2017-05-01

    Neutral beam injection (NBI) based on a negative ion source is one of the basic heating and current drive systems designed for ITER required to reach its goals of the operation with high fusion power, P fus ∼ 500 MW with fusion gain, Q = 10 for 400 s in a baseline scenario, and P fus > 250 MW, Q = 5 operation for 3600 s in an advanced scenario. A total power of 33 MW from the two heating neutral beam (HNB) injectors is envisaged in the present scenario. The scope of the present paper is to provide an overview of the main aspects of the interaction of the HNBs with the ITER plasma. Various operational scenarios with different mixtures of the main ion species, He, H, DD and DT, foreseen at different phases of the ITER operation are considered.

  15. Conceptual design of the DEMO neutral beam injectors: main developments and R&D achievements

    NASA Astrophysics Data System (ADS)

    Sonato, P.; Agostinetti, P.; Bolzonella, T.; Cismondi, F.; Fantz, U.; Fassina, A.; Franke, T.; Furno, I.; Hopf, C.; Jenkins, I.; Sartori, E.; Tran, M. Q.; Varje, J.; Vincenzi, P.; Zanotto, L.

    2017-05-01

    The objectives of the nuclear fusion power plant DEMO, to be built after the ITER experimental reactor, are usually understood to lie somewhere between those of ITER and a ‘first of a kind’ commercial plant. Hence, in DEMO the issues related to efficiency and RAMI (reliability, availability, maintainability and inspectability) are among the most important drivers for the design, as the cost of the electricity produced by this power plant will strongly depend on these aspects. In the framework of the EUROfusion Work Package Heating and Current Drive within the Power Plant Physics and Development activities, a conceptual design of the neutral beam injector (NBI) for the DEMO fusion reactor has been developed by Consorzio RFX in collaboration with other European research institutes. In order to improve efficiency and RAMI aspects, several innovative solutions have been introduced in comparison to the ITER NBI, mainly regarding the beam source, neutralizer and vacuum pumping systems.

  16. Experience with deuterium-tritium plasmas heated by high power neutral beams

    SciTech Connect

    Grisham, L.R.; Kamperschroer, J.H.; O`Connor, T.; Oldaker, M.; Stevenson, T.; Von Halle, A.

    1996-12-31

    The Tokamak Fusion Test Reactor has operated since November of 1993 with a deuterium-tritium fuel mixture for selected discharges. The majority of the tritium has been introduced as energetic neutral atoms of up to 120 keV injected by the neutral beam systems, with some of the twelve ion sources run on pure tritium and some on deuterium to optimize the fuel mixture in the core plasma. A maximum beam power of 39.6 megawatts has been injected, and deuterium-tritium fusion power production has reached 10.7 megawatts, achieving central fusion power densities comparable to or greater than those expected for the International Thermonuclear Reactor, and allowing the first studies of fusion-produced alpha particle behavior in reactor grade plasmas. Energy confinement in deuterium-tritium plasmas is better than in similar deuterium plasmas for most plasma regimes. Innovative techniques to manipulate the plasma current and pressure profiles are permitting studies of enhanced confinement regimes.

  17. Slow down of a globally neutral relativistic e-e+ beam shearing the vacuum

    NASA Astrophysics Data System (ADS)

    Alves, E. P.; Grismayer, T.; Silveirinha, M. G.; Fonseca, R. A.; Silva, L. O.

    2016-01-01

    The microphysics of relativistic collisionless shear flows is investigated in a configuration consisting of a globally neutral, relativistic {{e}-}{{e}+} beam streaming through a hollow plasma/dielectric channel. We show through multidimensional particle-in-cell simulations that this scenario excites the mushroom instability (MI), a transverse shear instability on the electron-scale, when there is no overlap (no contact) between the {{e}-}{{e}+} beam and the walls of the hollow plasma channel. The onset of the MI leads to the conversion of the beam’s kinetic energy into magnetic (and electric) field energy, effectively slowing down a globally neutral body in the absence of contact. The collisionless shear physics explored in this configuration may operate in astrophysical environments, particularly in highly relativistic and supersonic settings where macroscopic shear processes are stable.

  18. Instrumentation and control of the Doublet III Neutral Beam Injector System

    SciTech Connect

    Kohli, J.C.; Moore, C.D.; Drobnis, D.D.; Elischer, V.P.; Kilgore, R.; Uber, D.

    1980-03-01

    The hardware and software required for the operation of the Doublet III Neutral Beam Injector System (NBIS) are described. Development and implementation of this Instrumentation and Control System was divided between the major participants - General Atomic Company and Lawrence Berkeley Laboratory. The subdivision of responsibilities and the coordination of the participants' activities are described with reference to hardware and software requirements in support of the entire system. Included are a description of the operators' consoles, the interlock system and the CAMAC system. One feature of the control software is source modeling. This feature includes feedback on a shot to shot basis and adaptive control. Adaptive control permits the computer system to automatically adjust parameters after a shot, and to control the system to automatically compensate for time varying NBIS components. The Neutral Beam Power Supply features power supply modeling, fiber optic transmission of analog signals and digital control of power supply power-up/interlocks.

  19. Extreme ultraviolet diagnosis of a neutral-beam-heated mirror machine

    SciTech Connect

    Drake, R.P.

    1980-07-01

    Extreme ultraviolet emissions from the LLL 2XIIB fusion research experiment have been studied. (2XIIB was a magnetic-mirror-plasma-confinement device; beams of high-energy (20 keV) neutral deuterium created a high-density, high-temperature plasma.) A normal-incidence concave-grating monochromator, equipped with a windowless photomultiplier tube, was used to measure emissions in the spectral region from 400 Angstrom to 1600 A. Emissions of oxygen, titanium, carbon, nitrogen, and deuterium were identified; the oxygen brightnesses at times exceeded 10/sup 18/ ph-s/sup -1/-cm/sup -2/-sr/sup -1/. A survey of the emission characteristics found the oxygen concentration was 3%, the other impurities had concentrations near 0.4%. The radiated power loss was about 5% of the deposited neutral beam power.

  20. Study of the beam-foil excitation mechanism with the use of chlorine projectiles, 2-10 MeV

    NASA Astrophysics Data System (ADS)

    Jupén, C.; Denne, B.; Ekberg, J. O.; Engström, L.; Litzén, U.; Martinson, I.; Tai-Meng, W.; Trigueiros, A.; Veje, E.

    1982-11-01

    Beam-foil excitation of chlorine projectiles has been studied by means of optical spectrometry, at projectile energies ranging from 2 to 10 MeV. The relative populations of various levels in ClV through ClVIII have been measured as functions of the projectile energy. It is concluded that for ClVII and ClVIII, the 3p and 3d terms are populated entirely through molecular-orbital (MO) electron promotions. High-lying levels of these charge states are excited by means of pickup of electrons from the valence band of the solid. Intermediate levels are populated through multiple inner-shell processes as well as from valence-band electron pickup. For ClV and ClVI, most of the levels are excited predominantly by pickup of electrons from the valence band. However, for some of the valence-shell levels in ClVI, fairly strong contributions from MO processes are found at higher projectile energies. No evidence has been observed for direct Coulomb excitation.

  1. Fragmentation cross sections of 28Si at beam energies from 290AMeV to 1200A MeV

    SciTech Connect

    Zeitlin, C.; Fukumura, A.; Guetersloh, S.B.; Heilbronn, L.H; Iwata, Y.; Miller, J.; Murukami, T.

    2006-08-25

    In planning for long-duration spaceflight, it will beimportant to accurately model the exposure of astronauts to heavy ions inthe Galactic Cosmic Rays (GCR). As part of an ongoing effort to improveheavy-ion transport codes that will be used in designing futurespacecraft and habitats, fragmentation cross sections of 28Si have beenmeasured using beams with extracted energies from 290A MeV to 1200A MeV,spanning most of the peak region of the energy distribution of siliconions in the GCR. Results were obtained for six elemental targets:hydrogen, carbon, aluminum, copper, tin, and lead. The charge-changingcross sections are found to be energy-independent within the experimentaluncertainties, except for those on the hydrogen target. Cross sectionsfor the heaviest fragments are found to decrease slightly with increasingenergy for lighter targets, but increase with energy for tin and leadtargets. The cross sections are compared to previous measurements atsimilar energies, and to predictions of the NUCFRG2 model used by NASA toevaluate radiation exposures in flight. For charge-changing crosssections, reasonable agreement is found between the present experimentand those of Webber, et al. and Flesch, et al., and NUCFRG2 agrees withthe data to within 3 percent in most cases. Fragment cross sections showless agreement between experiments, and there are substantial differencesbetween NUCFRG2 predictions andthe data.

  2. An integral test of FLUKA nuclear models with 160 MeV proton beams in multi-layer Faraday cups

    NASA Astrophysics Data System (ADS)

    Rinaldi, I.; Ferrari, A.; Mairani, A.; Paganetti, H.; Parodi, K.; Sala, P.

    2011-07-01

    Monte Carlo (MC) codes are useful tools to simulate the complex processes of proton beam interactions with matter. In proton therapy, nuclear reactions influence the dose distribution. Therefore, the validation of nuclear models adopted in MC codes is a critical requisite for their use in this field. A simple integral test can be performed using a multi-layer Faraday cup (MLFC). This method allows separation of the nuclear and atomic interaction processes, which are responsible for secondary particle emission and the finite primary proton range, respectively. In this work, the propagation of 160 MeV protons stopping in two MLFCs made of polyethylene and copper has been simulated by the FLUKA MC code. The calculations have been performed with and without secondary electron emission and transport, as well as charge sharing in the dielectric layers. Previous results with other codes neglected those two effects. The impact of this approximation has been investigated and found to be relevant only in the proximity of the Bragg peak. Longitudinal charge distributions computed with FLUKA with both approaches have been compared with experimental data from the literature. Moreover, the contribution of different processes to the measurable signal has been addressed. A thorough analysis of the results has demonstrated that the nuclear and electromagnetic models of FLUKA reproduce the two sets of experimental data reasonably well.

  3. A comparison of the performance characteristics of four film dosimeters in a 10-MeV electron beam.

    PubMed

    Peimel-Stuglik, Zofia; Fabisiak, Sławomir

    2008-03-01

    Performance characteristics of four routine film dosimeters (CTA, B-3, PVC and LiF (Sunna)) in a 10-MeV electron beam were investigated. Dose response curves for the range 5-40kGy are presented. The dose response curve is linear for the CTA film, supralinear for the LiF (Sunna) film and sublinear for the B-3 and PVC films. The low sensitivity of the CTA film to ionizing radiation restricts its use to high doses, while the supralinear response curve of the LiF (Sunna) dosimeter allows this film to be used only in measurements of low doses. The optical absorption temperature coefficients for the CTA, B-3 and LiF (Sunna) films were found to be at the level of +/-0.1%/( composite function)C. The temperature coefficient for the PVC film decreased from +0.35%/( composite function)C immediately after irradiation to +0.04%/( composite function)C three months later. Because of the significant time dependence of the PVC film signal, a careful standardization of the heating regimen and of the time between the irradiations and measurements is necessary.

  4. Ion Beam Induced Charge Collection (IBICC) Studies of Integrated Circuits Using a 10MeV Carbon Microbeam

    SciTech Connect

    Aton, T.J.; Bouanani, M. E.; Doyle, B.L.; Duggan, J.L.; Guo, B.N.; McDaniel, F.D.; Renfrow, S.N.; Walsh, D.S.

    1998-09-29

    As feature sizes of Integrated Circuits (ICs) continue to shrinlL the sensitivity of these devices, particularly SRAMS and DR4Ms, to natural radiation is increasing. The radiation can lead to the uncontrolled deposition of charge within an IC, which ean alter, for example, the memoty state of a bit and thereby produce what is edled a `SOW error, or Single Event Upset (SEU). The response of ICS to natural background radiation is therefore of great coneem regarding the reliability of Mure devices. In this paper, we present results where Ion Beam Induced Charge Collection (TBICC) technique was used to simulate neutron-induced Si recoil dlkcts in IC test structures. The present wo~ wnducted at the San& National Laboratories, uses a 10 MeV Carbon mierobeam with 1 pm spot to scan test structures on specifically designed ICS. The test structure contains junctions typical of S RAMS and DRAMs. Charge is eolleeted from different areas of the IC under various conditions of junction back bias. The data are digitized and displayed as 3D images combined with KY) coordination. With the aid of IC layout informatio~ the 3D images are sepamted into difTerent layers to allow the identification of charge collection etlciency in the test structures. An analysis of the charge collection efficiency from dillerent test areas is given.

  5. Determination of neutral beam energy fractions from collisional radiative measurements on DIII-D

    SciTech Connect

    Thomas, D. M.; Van Zeeland, M. A.; Grierson, B. A.; Munoz Burgos, J. M.

    2012-10-15

    Neutral beams based on positive ion source technology are a key component of contemporary fusion research. An accurate assessment of the injected beam species mix is important for determining the actual plasma heating and momentum input as well as proper interpretation of beam-based diagnostics. On DIII-D, the main ion charge-exchange spectroscopy system is used to extract well-resolved intensity ratios of the Doppler-shifted D{sub {alpha}} emission from the full, half, and third energy beam components for a variety of beam operational parameters. In conjunction with accurate collisional-radiative modeling, these measurements indicate the assumed species mix and power fractions can vary significantly and should be regularly monitored and updated for the most accurate interpretation of plasma performance. In addition, if stable active control of the power fractions can be achieved through appropriate source tuning, the resulting control over the deposition profile can serve as an additional experimental knob for advanced tokamak studies, e.g., varying the off axis beam current drive without altering the beam trajectory.

  6. Determination of neutral beam energy fractions from collisional radiative measurements on DIII-D.

    PubMed

    Thomas, D M; Grierson, B A; Muñoz Burgos, J M; Van Zeeland, M A

    2012-10-01

    Neutral beams based on positive ion source technology are a key component of contemporary fusion research. An accurate assessment of the injected beam species mix is important for determining the actual plasma heating and momentum input as well as proper interpretation of beam-based diagnostics. On DIII-D, the main ion charge-exchange spectroscopy system is used to extract well-resolved intensity ratios of the Doppler-shifted D(α) emission from the full, half, and third energy beam components for a variety of beam operational parameters. In conjunction with accurate collisional-radiative modeling, these measurements indicate the assumed species mix and power fractions can vary significantly and should be regularly monitored and updated for the most accurate interpretation of plasma performance. In addition, if stable active control of the power fractions can be achieved through appropriate source tuning, the resulting control over the deposition profile can serve as an additional experimental knob for advanced tokamak studies, e.g., varying the off axis beam current drive without altering the beam trajectory.

  7. Mode particle resonances during near-tangential neutral beam injection in large tokamaks

    SciTech Connect

    Kaita, R.; White, R.B.; Morris, A.W.; Fredrickson, E.D.; McGuire, K.M.; Medley, S.S.; Scott, S.D.

    1988-01-01

    Coherent magnetohydrodynamic modes have been observed during neutral beam injection in TFTR and JET. Periodic bursts of oscillations were detected with several plasma diagnostics, and Fokker-Planck calculations show that the populations of trapped particles in both tokamaks are sufficient to account for fishbone destabilization. Estimates of mode parameters are in reasonable agreement with the experiments, and they indicate that the fishbone mode may continue to affect the performance of intensely heated tokamaks. 13 refs., 1 fig., 1 tab.

  8. Role of low-energy neutral N2 beam-surface interactions leading to spacecraft glow

    NASA Technical Reports Server (NTRS)

    Barnes, Alan V.; Albridge, Royal G.; Qi, Jining; Riehl-Chudoba, Manfred; Sun, Chang-Nian; Wang, P. W.; Tolk, Norman H.

    1990-01-01

    Measurements of the optical spectra of surfaces undergoing bombardment by N2 and N2(+) in an ultrahigh vacuum environment provide information related to the origin of spacecraft flow and erosion. This work is complementary to other measurements, in which O and O(+) beams are utilized. These efforts are part of a broad program whose goal is the understanding of interactions between surfaces and low-energy charged and neutral particles.

  9. Neutral Beam Injection Requirements and Design Issues for the National Compact Stellarator Experiment

    SciTech Connect

    H.W. Kugel; H. Neilson; W. Reiersen; M. Zarnstorff

    2002-02-11

    The National Compact Stellarator Experiment (NCSX) will require 6 MW of 50 keV neutral beam injection (NBI) with initial pulse lengths of 500 msec and upgradeable to pulse lengths of 1.5 sec. This paper discusses the NCSX NBI requirements and design issues, and shows how these are provided by the candidate PBX-M [Princeton Beta Experiment-Modification] NBI system.

  10. Radiation losses in PLT during neutral beam and ICRF heating experiments

    SciTech Connect

    Suckewer, S.; Hinnov, E.; Hwang, D.

    1981-02-01

    Radiation and charge exchange losses in the PLT tokamak are compared for discharges with ohmic heating only (OH), and with additional heating by neutral beams (NB) or RF in the ion cyclotron frequency range (ICRF). Spectroscopic, bolometric and soft x-ray diagnostics were used. The effects of discharge cleaning, vacuum wall gettering, and rate of gas inlet on radiation losses from OH plasmas and the correlation between radiation from plasma core and edge temperatures are discussed.

  11. Cold-cathode Penning discharge-based ionizer for detection of hyperthermal neutral beams.

    PubMed

    Abolmasov, S N; Samukawa, S

    2007-07-01

    Plasmas produced in a cold-cathode Penning discharge have been studied for possible use as an active ionizing medium in commercial quadrupole mass/energy analyzers for detection of low-energy neutral beams. Two distinct Penning discharge modes have been examined: (1) high-pressure (HP) mode and (2) high magnetic field (HMF) mode. It is shown that the ionization efficiency in the HP mode is independent of the length of ionization region; however, somewhat high working pressures (p>10(-4) Torr) and large discharge currents limit the practical use of this mode. This is not the case in the HMF mode, which appears at lower pressures, with an effective ionization region length of the order of electron cyclotron radius. The design and operation of a compact (5x4x4 cm(3)), low-maintenance ionizer based on a Penning cell with permanent magnets is described. The ability to ionize 40 eV neutral-argon beams with subsequent detection in a Hiden EQP energy-resolved mass spectrometer is shown. The ionization efficiency of the ionizer was found to be as high as 10(-3). Unlike conventional electron impact ionizers, the Penning discharge configuration allows to eliminate the thermal background component in the detected signal. The ionizer has potential application for the detection of hyperthermal neutral beams of various species.

  12. Slow down of a globally neutral relativistic e-e + beam shearing the vacuum

    NASA Astrophysics Data System (ADS)

    Alves, E. P.; Grismayer, T.; Silveirinha, M. G.; Fonseca, R. A.; Silva, L. O.

    2015-11-01

    It has been recently found that the development of electromagnetic instabilities between shearing, globally neutral polarisable dielectric slabs, separated by a nanometer-scale gap, can result in an effective non-contact friction force between slavs, which is the classical analogue of the quantum friction effect proposed by Pendry (1997). This effect has been explored analytically in the sub-relativistic regime, where the development of unstable electromagnetic modes parallel to the direction of motion are responsible for the non-contact friction effect. We explore the interaction of a relativistic, globally neutral e-e + beam streaming through a hollow plasma/dielectric in the absence of overlap (no contact). We show through analytic theory and 3D particle-in-cell simulations that this relativistic scenario excites unstable electromagnetic modes transverse to the direction of propagation. The onset of this electromagnetic instability leads to the conversion of the kinetic energy of the e-e + beam into electric and magnetic field energy, effectively slowing down a relativistic, globally neutral body in the absence of contact. We demonstrate that this effect be explored using beam properties that are readily available at the SLAC National Accelerator Laboratory.

  13. Multiple track Doppler-shift spectroscopy system for TFTR neutral beam injectors

    SciTech Connect

    Kamperschroer, J.H.; Kugel, H.W.; Reale, M.A.; Hayes, S.L.; Johnson, G.A.; Lowrance, J.L.; Shah, P.A.; Sichta, P.; Sleaford, B.W.; Williams, M.D.; Zucchino, P.M.

    1986-09-01

    A Doppler-shift spectroscopy system has been installed on the TFTR neutral beam injection system to measure species composition during both conditioning and injection pulses. Two intensified vidicon detectors and two spectrometers are utilized in a system capable of resolving data from up to twelve ion sources simultaneously. By imaging the light from six ion sources onto one detector, a cost-effective system has been achieved. Fiber optics are used to locate the diagnostic in an area remote from the hazards of the tokamak test cell allowing continuous access, and eliminating the need for radiation shielding of electronic components. Automatic hardware arming and interactive data analysis allow beam composition to be computed between tokamak shots for use in analyzing plasma heating experiments. Measurements have been made using lines of sight into both the neutralizer and the drift duct. Analysis of the data from the drift duct is both simpler and more accurate since only neutral particles are present in the beam at this location. Comparison of the data taken at these two locations reveals the presence of partially accelerated particles possessing an estimated 1/e half-angle divergence of 15/sup 0/ and accounting for up to 30% of the extracted power.

  14. Doublet III Neutral Beam Heating Project: Final report for the period FY78 through FY81

    SciTech Connect

    Colleraine, A.

    1987-05-01

    The Neutral Beam Project final scope of work consisted of procurement, fabrication, assembly, test, and installation of two neutral beam injection systems for the DIII machine. One of these NBIS was installed and operated at the 210/sup 0/ location; the second was placed at the 330/sup 0/ location. The Doublet III Neutral Beam Administrative Plan defined the technical, cost, and schedule requirements necessary to achieve the program objectives. These requirements are presented in the form of Baseline Definitions: Technical, Cost, Schedule which are contained in this Administrative Plan. These Baselines formed the basis for control of not only the overall program but of each major participant. GA, LBL, and TRW were assigned specific scopes of work within the Baselines to be accomplished in order to meet the overall program objectives. To accomplish these work scopes, GA, LBL, and TRW each established within their own project organization, a system for controlling and accomplishing work which is compatible with and complementary to the overall management system at GA. 21 figs., 5 tabs.

  15. The PRIMA Test Facility: SPIDER and MITICA test-beds for ITER neutral beam injectors

    NASA Astrophysics Data System (ADS)

    Toigo, V.; Piovan, R.; Dal Bello, S.; Gaio, E.; Luchetta, A.; Pasqualotto, R.; Zaccaria, P.; Bigi, M.; Chitarin, G.; Marcuzzi, D.; Pomaro, N.; Serianni, G.; Agostinetti, P.; Agostini, M.; Antoni, V.; Aprile, D.; Baltador, C.; Barbisan, M.; Battistella, M.; Boldrin, M.; Brombin, M.; Dalla Palma, M.; De Lorenzi, A.; Delogu, R.; De Muri, M.; Fellin, F.; Ferro, A.; Fiorentin, A.; Gambetta, G.; Gnesotto, F.; Grando, L.; Jain, P.; Maistrello, A.; Manduchi, G.; Marconato, N.; Moresco, M.; Ocello, E.; Pavei, M.; Peruzzo, S.; Pilan, N.; Pimazzoni, A.; Recchia, M.; Rizzolo, A.; Rostagni, G.; Sartori, E.; Siragusa, M.; Sonato, P.; Sottocornola, A.; Spada, E.; Spagnolo, S.; Spolaore, M.; Taliercio, C.; Valente, M.; Veltri, P.; Zamengo, A.; Zaniol, B.; Zanotto, L.; Zaupa, M.; Boilson, D.; Graceffa, J.; Svensson, L.; Schunke, B.; Decamps, H.; Urbani, M.; Kushwah, M.; Chareyre, J.; Singh, M.; Bonicelli, T.; Agarici, G.; Garbuglia, A.; Masiello, A.; Paolucci, F.; Simon, M.; Bailly-Maitre, L.; Bragulat, E.; Gomez, G.; Gutierrez, D.; Mico, G.; Moreno, J.-F.; Pilard, V.; Kashiwagi, M.; Hanada, M.; Tobari, H.; Watanabe, K.; Maejima, T.; Kojima, A.; Umeda, N.; Yamanaka, H.; Chakraborty, A.; Baruah, U.; Rotti, C.; Patel, H.; Nagaraju, M. V.; Singh, N. P.; Patel, A.; Dhola, H.; Raval, B.; Fantz, U.; Heinemann, B.; Kraus, W.; Hanke, S.; Hauer, V.; Ochoa, S.; Blatchford, P.; Chuilon, B.; Xue, Y.; De Esch, H. P. L.; Hemsworth, R.; Croci, G.; Gorini, G.; Rebai, M.; Muraro, A.; Tardocchi, M.; Cavenago, M.; D'Arienzo, M.; Sandri, S.; Tonti, A.

    2017-08-01

    The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes two experiments: MITICA, the full-scale prototype of the ITER heating neutral beam injector, and SPIDER, the full-size radio frequency negative-ions source. The NBTF realization and the exploitation of SPIDER and MITICA have been recognized as necessary to make the future operation of the ITER heating neutral beam injectors efficient and reliable, fundamental to the achievement of thermonuclear-relevant plasma parameters in ITER. This paper reports on design and R&D carried out to construct PRIMA, SPIDER and MITICA, and highlights the huge progress made in just a few years, from the signature of the agreement for the NBTF realization in 2011, up to now—when the buildings and relevant infrastructures have been completed, SPIDER is entering the integrated commissioning phase and the procurements of several MITICA components are at a well advanced stage.

  16. Focusing of a neutral helium beam with a photon-sieve structure

    NASA Astrophysics Data System (ADS)

    Eder, S. D.; Guo, X.; Kaltenbacher, T.; Greve, M. M.; Kalläne, M.; Kipp, L.; Holst, B.

    2015-04-01

    The manipulation of low-energy beams of neutral atoms and molecules via their de Broglie wavelength is a branch of atom optics often referred to as de Broglie matter wave optics. The application areas include fundamental quantum mechanics, atom interferometry, and the development of new microscopy instrumentation. The focusing of de Broglie matter waves with a Fresnel zone plate was used to demonstrate the first neutral helium microscopy imaging. The ultimate resolution of such a microscope is limited by the width of the outermost zone. Because a Fresnel zone plate for atoms cannot be fabricated on a substrate (the low-energy atom beams would not be able to penetrate the substrate material), this gives a fabrication determined limit for the first-order focus of around 30-50 nm. Therefore, it is important to search for alternative optical elements that enable higher resolution. Photon sieves consist of a large number of pinholes, arranged suitably relative to the Fresnel zones. The great advantages are that the width of the pinholes can be larger than the respective Fresnel zones and a free-standing pinhole is much easier to fabricate than a free-standing zone. Thus, with a photon-sieve structure applied for de Broglie matter wave manipulation, the fabrication limit for focusing is reduced to potentially around 3-5 nm. Here we present a realization of such an "atom sieve," which we fabricated out of a silicon nitride (SiN) membrane, using electron-beam lithography and reactive ion etching. Our atom sieve is 178 μ m in diameter and has 31 991 holes. The diameter of the holes varies from 1840 to 150 nm. Using a beam of neutral, ground-state helium atoms with an average wavelength of 0.055 nm, we demonstrate helium atom focusing down to a spot size of less than 4 μ m . The focus size is limited by the intrinsic velocity spread of the helium beam.

  17. Determination of neutral beam direction from radiation emitted by photodetached H/sup -/

    SciTech Connect

    Hershcovitch, A.

    1986-01-01

    Non-destructive diagnostic techniques to determine beam direction of 200 MeV H/sup 0/ atoms are analyzed. These methods are based on excited hydrogen atoms in n=2 and n=3 levels due to photodetachment of H/sup -/ ions. With some development of hot cathodes, an e-beam driven ArF laser can produce H*(2s) atoms for laser resonance fluorescence by photoneutralizing H/sup -/ ions in a quantity comparable to that of a gas cell. Observation of fluorescence from spontaneous decay of H*(2p) or induced decay of H*(2s) can be readily used to indicated beam orientation with a 40 ..mu..rad accuracy. Measurements of minute Doppler shifts of this Lyman Alpha radiation by a spectrograph could in principle resolve beam direction to within 2.8 ..mu..rad. For schemes requiring n=3 hydrogen atoms, a Xe laser can produce H*(3s) or H*(3p) atoms in quantities larger than previously published. 11 refs., 3 figs.

  18. High-energy tritium beams as current drivers in tokamak reactors

    SciTech Connect

    Mikkelsen, D.R.; Grisham, L.R.

    1983-04-01

    The effect on neutral-beam design and reactor performance of using high-energy (approx. 3-10 MeV) tritium neutral beams to drive steady-state tokamak reactors is considered. The lower current of such beams leads to several advantages over lower-energy neutral beams. The major disadvantage is the reduction of the reactor output caused by the lower current-drive efficiency of the high-energy beams.

  19. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Rajawat, R. K.; DasGupta, K.

    2016-01-01

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ˜1012-1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  20. Specific features of measuring the isotopic composition of hydrogen ions in ITER plasma by using neutral particle diagnostics under neutral beam injection conditions

    SciTech Connect

    Afanasyev, V. I.; Goncharov, P. R.; Mironov, M. I.; Nesenevich, V. G. Petrov, M. P.; Petrov, S. Ya.; Sergeev, V. Yu.

    2015-12-15

    Results of numerical simulation of signals from neutral particle analyzers under injection of the heating and diagnostic neutral beams in different operating modes of the ITER tokamak are presented. The distribution functions of fast ions in plasma are simulated, and the corresponding neutral particle fluxes escaping from the plasma along the line of sight of the analyzers are calculated. It is shown that the injection of heating deuterium (D{sup 0}) beams results in the appearance of an intense background signal hampering measurements of the ratio between the densities of deuterium and tritium fuel ions in plasma in the thermal energy range. The injection of a diagnostic hydrogen (H{sup 0}) beam does not affect measurements owing to the high mass resolution of the analyzers.

  1. Physics design of the injector source for ITER neutral beam injector (invited)

    SciTech Connect

    Antoni, V.; Agostinetti, P.; Aprile, D.; Chitarin, G.; Fonnesu, N.; Marconato, N.; Pilan, N.; Sartori, E.; Serianni, G. Veltri, P.; Cavenago, M.

    2014-02-15

    Two Neutral Beam Injectors (NBI) are foreseen to provide a substantial fraction of the heating power necessary to ignite thermonuclear fusion reactions in ITER. The development of the NBI system at unprecedented parameters (40 A of negative ion current accelerated up to 1 MV) requires the realization of a full scale prototype, to be tested and optimized at the Test Facility under construction in Padova (Italy). The beam source is the key component of the system and the design of the multi-grid accelerator is the goal of a multi-national collaborative effort. In particular, beam steering is a challenging aspect, being a tradeoff between requirements of the optics and real grids with finite thickness and thermo-mechanical constraints due to the cooling needs and the presence of permanent magnets. In the paper, a review of the accelerator physics and an overview of the whole R and D physics program aimed to the development of the injector source are presented.

  2. Physics design of the injector source for ITER neutral beam injector (invited).

    PubMed

    Antoni, V; Agostinetti, P; Aprile, D; Cavenago, M; Chitarin, G; Fonnesu, N; Marconato, N; Pilan, N; Sartori, E; Serianni, G; Veltri, P

    2014-02-01

    Two Neutral Beam Injectors (NBI) are foreseen to provide a substantial fraction of the heating power necessary to ignite thermonuclear fusion reactions in ITER. The development of the NBI system at unprecedented parameters (40 A of negative ion current accelerated up to 1 MV) requires the realization of a full scale prototype, to be tested and optimized at the Test Facility under construction in Padova (Italy). The beam source is the key component of the system and the design of the multi-grid accelerator is the goal of a multi-national collaborative effort. In particular, beam steering is a challenging aspect, being a tradeoff between requirements of the optics and real grids with finite thickness and thermo-mechanical constraints due to the cooling needs and the presence of permanent magnets. In the paper, a review of the accelerator physics and an overview of the whole R&D physics program aimed to the development of the injector source are presented.

  3. First measurement of the polarisation asymmetry of a gamma-ray beam between 1.7 to 74 MeV with the HARPO TPC

    NASA Astrophysics Data System (ADS)

    Gros, P.; Amano, S.; Attié, D.; Bernard, D.; Bruel, P.; Calvet, D.; Colas, P.; Daté, S.; Delbart, A.; Frotin, M.; Geerebaert, Y.; Giebels, B.; Götz, D.; Hashimoto, S.; Horan, D.; Kotaka, T.; Louzir, Marc; Minamiyama, Y.; Miyamoto, S.; Ohkuma, H.; Poilleux, Patrick; Semeniouk, I.; Sizun, P.; Takemoto, A.; Yamaguchi, M.; Wang, S.

    2016-07-01

    Current γ-ray telescopes suffer from a gap in sensitivity in the energy range between 100 keV and 100 MeV, and no polarisation measurement has ever been done on cosmic sources above 1 MeV. Past and present e+e- pair telescopes are limited at lower energies by the multiple scattering of electrons in passive tungsten converter plates. This results in low angular resolution, and, consequently, a drop in sensitivity to point sources below 1 GeV. The polarisation information, which is carried by the azimuthal angle of the conversion plane, is lost for the same reasons. HARPO is an R&D program to characterise the operation of a gaseous detector (a Time Projection Chamber or TPC) as a high angular-resolution and sensitivity telescope and polarimeter for γ-rays from cosmic sources. It represents a first step towards a future space instrument in the MeV-GeV range. We built and characterised a 30cm cubic demonstrator [SPIE 91441M], and put it in a polarised γ-ray beam at the NewSUBARU accelerator in Japan. Data were taken at photon energies from 1.74MeV to 74MeV and with different polarisation configurations. We describe the experimental setup in beam. We then describe the software we developed to reconstruct the photon conversion events, with special focus on low energies. We also describe the thorough simulation of the detector used to compare results. Finally we will present the performance of the detector as extracted from this analysis and preliminary measurements of the polarisation asymmetry. This beam-test qualification of a gas TPC prototype in a γ-ray beam could open the way to high-performance -ray astronomy and polarimetry in the MeV-GeV energy range in the near future.

  4. Experiments investigating the generation and transport of 10--12 MeV, 30-kA, mm-size electron beams with linear inductive voltage adders

    SciTech Connect

    Mazarakis, M.G.; Poukey, J.W.; Maenchen, J.E.

    1997-06-01

    The authors present the design, analysis, and results of the high-brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: 8--12 MeV, 35--50 kA, 30--60 ns FWHM, and 0.5-mm rms beam radius. The accelerators utilized are SABRE and HERMES III. Both are linear inductive voltage adders modified to higher impedance and fitted with magnetically immersed foil less electron diodes. In the strong 20--50 Tesla solenoidal magnetic field of the diode, mm-size electron beams are generated and propagated to a beam stop. The electron beam is field emitted from mm-diameter needle-shaped cathode electrode and is contained in a similar size envelop by the strong magnetic field. These extremely space charge dominated beams provide the opportunity to study beam dynamics and possible instabilities in a unique parameter space. The SABRE experiments are already completed and have produced 30-kA, 1.5-mm FWHM electron beams, while the HERMES-III experiments are on-going.

  5. A Study of Spectral Lines in Plasmas Heated by Neutral Beam Injection in the TJ-II Stellarator

    SciTech Connect

    McCarthy, Kieran J.; Carmona, J. M.; Balbin, R.

    2008-10-22

    We summarize the TJ-II stellarator device give an outline of a vacuum ultraviolet spectrometer used for performing spectral surveys specialized plasma studies. Next, we report the main impurities observed in hot plasmas created maintained by electron cyclotron resonance neutral beam injection heating with lithium coated wall conditioning. Finally, we report broad emission structures that have been observed close to strong oxygen emission lines during neutral beam injection heating phases we elucidate their possible origin.

  6. Neutral-beam current-driven high-poloidal-beta operation of the DIII-D tokamak

    NASA Astrophysics Data System (ADS)

    Simonen, T. C.; Matsuoka, M.; Bhadra, D. K.; Burrell, K. H.; Callis, R. W.; Chance, M. S.; Chu, M. S.; Greene, J. M.; Groebner, R. J.; Harvey, R. W.; Hill, D. N.; Kim, J.; Lao, L.; Petersen, P. I.; Porter, G. D.; St. John, H.; Stallard, B. W.; Stambaugh, R. D.; Strait, E. J.; Taylor, T. S.

    1988-10-01

    Neutral-beam current-drive experiments in the DIII-D tokamak with a single null poloidal divertor are described. A plasma current of 0.34 MA has been sustained by neutral beams alone, and the energy confinement is of H-mode quality. Poloidal β values reach 3.5 without disruption or coherent magnetic activity suggesting that these plasmas may be entering the second stability regime.

  7. Neutral particle measurements of fusion tritons in JET

    SciTech Connect

    Afanasyev, V. I.; Khudoleev, A. V.

    2010-08-15

    A neutral particle analyzer [A.D. Izvozchikov et al., JET Report No. JET-R(91)-12, 1991] operating in the MeV energy range was used to measure the flux of neutralized d-d fusion tritons emitted from the hot-ion H-mode deuterium plasma heated by deuterium neutral beams. It was found that tritons in the energy range of 0.3-1.1 MeV were largely neutralized by the beam atoms and the beam halo atoms. This enabled us to find the localized energy distribution function of the fusion tritons in the central plasma region. Simulation of the triton energy distribution function shows that MeV ions in the JET hot-ion H-mode plasma behave classically.

  8. Proton beam simulation with MCNPX: Gallium metal activation estimates below 30 MeV relevant to the bulk production of 68Ge and 65Zn

    NASA Astrophysics Data System (ADS)

    Fassbender, M.; Arzumanov, A.; Jamriska, D. J.; Lyssukhin, S. N.; Trellue, H.; Waters, L. S.

    2007-08-01

    Several gallium metal targets containing Ga metal encapsulated in Nb shells were irradiated in a 30 MeV cyclotron beam. Proton and secondary neutron beam fluences as well as radionuclide activity formation were modeled using MCNP-X in combination with CINDER90. Targets were chemically processed using two anion exchange steps. Good agreement between measured radiochemical yields and MCNPX/CINDER estimates was observed. The separation principle introduced in this work was utilized for a small 68Ge/Ga generator column for 68Ga labeling purposes.

  9. A study of gamma-ray and neutron radiation in the interaction of a 2 MeV proton beam with various materials.

    PubMed

    Kasatov, D; Makarov, A; Shchudlo, I; Taskaev, S

    2015-12-01

    Epithermal neutron source based on a tandem accelerator with vacuum insulation and lithium target has been proposed, developed and operated in Budker Institute of Nuclear Physics. The source is regarded as a prototype of a future compact device suitable for carrying out BNCT in oncology centers. In this work the measurements of gamma-ray and neutron radiation are presented for the interaction of a 2 MeV proton beam with various materials (Li, C, F, Al, V, Ti, Cu, Mo, stainless steel, and Ta). The obtained results enabled the optimization of the neutron-generating target and the high energy beam transportation path. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Improvement of a block co-polymer (PS-b-PMMA)-masked silicon etch profile using a neutral beam

    NASA Astrophysics Data System (ADS)

    Yun, Deokhyun; Park, Jinwoo; Kim, Hwasung; Mun, Jeongho; Kim, Sangouk; Kim, Kyongnam; Yeom, Geunyoung

    2016-09-01

    Bottom-up block copolymer (BCP) lithography mediated by self-assembly of polystyrene (PS)/poly-methyl methacrylate (PMMA) is widely used as an alternative patterning method for various deep nanoscale devices, such as optical devices and transistors, replacing conventional top-down photolithography. However, the nanoscale BCP mask features formed on the substrates after direct self-assembly of BCP tend to be easily damaged during exposure to the following plasma processing. In this study, silicon masked with a nanoscale BCP mask (PS) was etched by irradiating with a Cl2/Ar neutral beam in addition to a Cl2/Ar ion beam, and the effect of a Cl2/Ar neutral beam instead of a Cl2/Ar ion beam on damage to the PS mask and the silicon etch characteristics of nanodevices was investigated. The results show that the use of a neutral beam instead of an ion beam decreased degradation of the BCP mask during etching; therefore, a more anisotropic silicon etch profile in addition to improved etch selectivity of silicon compared to the BCP mask was observed. Moreover, by using the neutral beam, the sidewall roughness and sidewall angle also improved due to the decreased surface charge and reduced damage to the nanoscale PS mask resulting from use of a highly directional radical beam instead of a conventional ion-based beam.

  11. Improvement of a block co-polymer (PS-b-PMMA)-masked silicon etch profile using a neutral beam.

    PubMed

    Yun, Deokhyun; Park, Jinwoo; Kim, Hwasung; Mun, Jeongho; Kim, Sangouk; Kim, Kyongnam; Yeom, Geunyoung

    2016-09-23

    Bottom-up block copolymer (BCP) lithography mediated by self-assembly of polystyrene (PS)/poly-methyl methacrylate (PMMA) is widely used as an alternative patterning method for various deep nanoscale devices, such as optical devices and transistors, replacing conventional top-down photolithography. However, the nanoscale BCP mask features formed on the substrates after direct self-assembly of BCP tend to be easily damaged during exposure to the following plasma processing. In this study, silicon masked with a nanoscale BCP mask (PS) was etched by irradiating with a Cl2/Ar neutral beam in addition to a Cl2/Ar ion beam, and the effect of a Cl2/Ar neutral beam instead of a Cl2/Ar ion beam on damage to the PS mask and the silicon etch characteristics of nanodevices was investigated. The results show that the use of a neutral beam instead of an ion beam decreased degradation of the BCP mask during etching; therefore, a more anisotropic silicon etch profile in addition to improved etch selectivity of silicon compared to the BCP mask was observed. Moreover, by using the neutral beam, the sidewall roughness and sidewall angle also improved due to the decreased surface charge and reduced damage to the nanoscale PS mask resulting from use of a highly directional radical beam instead of a conventional ion-based beam.

  12. The effect of Ar neutral beam treatment of screen-printed carbon nanotubes for enhanced field emission

    SciTech Connect

    Kyung, Se Jin; Park, Jae Beom; Park, Byung Jae; Min, Kyung Seok; Lee, June Hee; Yeom, Geun Young; Shin, Yong Sook; Park, Chong Yun

    2007-04-15

    This study examined the effectiveness of an Ar neutral beam as a surface treatment for improving the field emission properties of screen-printed carbon nanotubes (CNTs). A short period of the neutral beam treatment on tape-activated CNTs enhanced the emission properties of the CNTs, showing a decrease in the turn-on field and an increase in the number of emission sites. The neutral beam treatment appeared to render the CNT surfaces more actively by exposing more CNTs from the CNT paste without cutting or kinking the already exposed long CNT emitters. The treated CNTs emitted more electrons than the CNTs treated using other methods. When the field emission properties were measured after the neutral beam treatment, the turn-on field decreased from 1.65 to 0.60 V/{mu}m and the emission field at 1 mA/cm{sup 2} decreased from 3.10 to 2.41 V/{mu}m. After the neutral beam treatment for 10 s, there was an improvement in the stability of the emission current at a constant electric field. It is expected that the neutral beam treatment introduced in this study will provide an easy way of improving the emission intensity and stability of screen-printed CNT emitters.

  13. Neutral beam system for the C-2-Upgrade Field Reversed Configuration Experiment

    NASA Astrophysics Data System (ADS)

    Korepanov, Sergey; Smirnov, Artem; Clary, Ryan; Dunaevsky, Alexandr; Isakov, Ivan; Magee, Richard; Matvienko, Vasily; van Drie, Alan; Deichuli, Petr; Ivanov, Alexandr; Pirogov, Konstantin; Sorokin, Aleksey; Stupishin, Nickolay; Vakhrushev, Roman; TAE Team; Budker Team

    2015-11-01

    In the C-2 field-reversed configuration (FRC) experiment, tangential neutral beam injection (NBI), coupled with electrically-biased plasma guns at the plasma ends and advanced surface conditioning, led to dramatic reductions in turbulence-driven losses. Under such conditions, highly reproducible, macroscopically stable, hot FRCs with a significant fast-ion population, total plasma temperature of ~ 1 keV and record lifetimes were achieved. To further improve the FRC sustainment and provide a better coupling with beams, the C-2 device has been upgraded with a new NBI system, which can deliver up to a total of 10 MW of hydrogen beam power (15 keV, 8 ms pulse), by far the largest ever used in compact toroid plasma experiments. The NBI system consists of six positive-ion based injectors featuring flexible, modular design. This presentation will provide an overview of the C-2U NBI system, including: 1) NBI test facility, beam characterization, and acceptance tests, 2) integration with the machine and operating experience, 3) improvements in plasma performance with increased beam power.

  14. Current neutralization and focusing of intense ion beams with a plasma-filled solenoidal lens. I

    SciTech Connect

    Oliver, B.V.; Sudan, R.N.

    1996-12-01

    The response of the magnetized plasma in an axisymmetric, plasma-filled, solenoidal magnetic lens, to intense light ion beam injection is studied. The lens plasma fill is modeled as an inertialess, resistive, electron magnetohydrodynamic (EMHD) fluid since characteristic beam times {tau} satisfy 2{pi}/{omega}{sub {ital pe}},2{pi}/{Omega}{sub {ital e}}{lt}{tau}{le}2{pi}/{Omega}{sub {ital i}} ({omega}{sub {ital pe}} is the electron plasma frequency and {Omega}{sub {ital e},{ital i}} are the electron, ion gyrofrequencies). When the electron collisionality satisfies {nu}{sub {ital e}}{lt}{Omega}{sub {ital e}}, the linear plasma response is determined by whistler wave dynamics. In this case, current neutralization of the beam is reduced on the time scale for whistler wave transit across the beam. The transit time is inversely proportional to the electron density and proportional to the angle of incidence of the beam with respect to the applied solenoidal field. In the collisional regime ({nu}{sub {ital e}}{gt}{Omega}{sub {ital e}}) the plasma return currents decay on the normal diffusive time scale determined by the conductivity. The analysis is supported by two-and-one-half dimensional hybrid particle-in-cell simulations. {copyright} {ital 1996 American Institute of Physics.}

  15. Steady state performance test analysis of actively cooled extractor grids for SST-1 neutral beam injector

    SciTech Connect

    Jana, M. R.; Mattoo, S. K.; Khan, M.

    2010-11-15

    Neutral beam injection (NBI) system is a workhorse to heat magnetically confined tokamak fusion plasma. The heart of any NBI system is an ion extractor system. Steady State Superconducting Tokamak-1 (SST-1) needs 0.5 MW of hydrogen beam power at 30 kV to raise the plasma ion temperature to {approx}1 keV and 1.7 MW of hydrogen beam power at 55 kV for future upgradation. To meet this requirement, an ion extractor system consisting of three actively cooled grids has been designed, fabricated, and its performance test has been done at MARION test stand, IPP, Julich, Germany. During long pulse (14 s) operation, hydrogen ion beam of energy 31 MJ has been extracted at 41 kV. In this paper, we have presented detailed analysis of calorimetric data of actively cooled extractor grids and showed that by monitoring outlet water temperature, grid material temperature can be monitored for safe steady state operation of a NBI system. Steady state operation of NBI is the present day interest of fusion research. In the present experimental case, performance test analysis indicates that the actively cooled grids attain steady state heat removal condition and the grid material temperature rise is {approx}18 deg. C and saturates after 10 s of beam pulse.

  16. Steady state performance test analysis of actively cooled extractor grids for SST-1 neutral beam injector.

    PubMed

    Jana, M R; Mattoo, S K; Khan, M

    2010-11-01

    Neutral beam injection (NBI) system is a workhorse to heat magnetically confined tokamak fusion plasma. The heart of any NBI system is an ion extractor system. Steady State Superconducting Tokamak-1 (SST-1) needs 0.5 MW of hydrogen beam power at 30 kV to raise the plasma ion temperature to ~1 keV and 1.7 MW of hydrogen beam power at 55 kV for future upgradation. To meet this requirement, an ion extractor system consisting of three actively cooled grids has been designed, fabricated, and its performance test has been done at MARION test stand, IPP, Julich, Germany. During long pulse (14 s) operation, hydrogen ion beam of energy 31 MJ has been extracted at 41 kV. In this paper, we have presented detailed analysis of calorimetric data of actively cooled extractor grids and showed that by monitoring outlet water temperature, grid material temperature can be monitored for safe steady state operation of a NBI system. Steady state operation of NBI is the present day interest of fusion research. In the present experimental case, performance test analysis indicates that the actively cooled grids attain steady state heat removal condition and the grid material temperature rise is ~18°C and saturates after 10 s of beam pulse.

  17. Progress on the Implementation of a Neutral Beam for the Lithium Tokamak eXperiment-Beta

    NASA Astrophysics Data System (ADS)

    Merino, Enrique; Kozub, Thomas; Boyle, Dennis; Majeski, Richard; Kaita, Robert; Smirnov, Artem; Catalano, Ryan

    2016-10-01

    In the Lithium Tokamak eXperiment (LTX), good performance discharges have been achieved with reduced-recycling lithium walls. Two hydrogen neutral beams (NB) have been loaned to the LTX project by Tri-Alpha Energy, Inc. To further improve plasma parameters, one of these neutral beams is being installed as part of an upgrade to LTX (LTX-Beta). Current ohmic input power in LTX is less than 100 kW. The NB will provide core plasma fueling with up to 700 kW of injected power. Requirements for accommodating the NB include the addition of injection and beam-dump ports on the vessel, and their designs have been finalized. Progress has also been made on the NB power supplies, including the preparation of a new room to accommodate them. A description of these activities and the status of other improvements to LTX for LTX-Beta will be presented. Work supported by US DOE contracts DE-AC02- 09CH11466 and DE-AC05- 00OR22725.

  18. Fast neutral beam ion source coupled to a Fourier transform ion cyclotron resonance mass spectrometer

    NASA Astrophysics Data System (ADS)

    Hill, Nicholas C.; Limbach, Patrick A.; Shomo, Ronald E., II; Marshall, Alan G.; Appelhans, Anthony D.; Delmore, James E.

    1991-11-01

    The coupling of an autoneutralizing SF-6 fast ion-beam gun to a Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometer is described. The fast neutral beam provides for secondary-ion-type FT/ICR mass analysis [e.g., production of abundant pseudomolecular (M+H)+ ions] of involatile samples without the need for external ion injection, since ions are formed at the entrance to the ICR ion trap. The design, construction, and testing of the hybrid instrument are described. The feasibility of the experiment (for both broadband and high-resolution FT/ICR positive-ion mass spectra) is demonstrated with tetra-butylammonium bromide and a Tylenol■ sample. The ability to analyze high molecular weight polymers with high mass resolution is demonstrated for Teflon■. All of the advantages of the fast neutral beam ion source previously demonstrated with quadrupole mass analysis are preserved, and the additional advantages of FT/ICR mass analysis (e.g., high mass resolving power, ion trapping) are retained.

  19. Fast neutral beam ion source coupled to a Fourier transform ion cyclotron resonance mass spectrometer

    SciTech Connect

    Hill, N.C.; Limbach, P.A.; Shomo, R.E. II; Marshall, A.G. ); Appelhans, A.D.; Delmore, J.E. )

    1991-11-01

    The coupling of an autoneutralizing SF{sup {minus}}{sub 6} fast ion-beam gun to a Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometer is described. The fast neutral beam provides for secondary-ion-type FT/ICR mass analysis (e.g., production of abundant pseudomolecular (M+H){sup +} ions) of involatile samples without the need for external ion injection, since ions are formed at the entrance to the ICR ion trap. The design, construction, and testing of the hybrid instrument are described. The feasibility of the experiment (for both broadband and high-resolution FT/ICR positive-ion mass spectra) is demonstrated with {ital tetra}-butylammonium bromide and a Tylenol{sup ( )} sample. The ability to analyze high molecular weight polymers with high mass resolution is demonstrated for Teflon{sup ( )}. All of the advantages of the fast neutral beam ion source previously demonstrated with quadrupole mass analysis are preserved, and the additional advantages of FT/ICR mass analysis (e.g., high mass resolving power, ion trapping) are retained.

  20. Heat flux to the limiter during disruptions and neutral beam injection in Doublet-III

    NASA Astrophysics Data System (ADS)

    Hino, T.; DeGrassie, J.; Taylor, T. S.; Hopkins, G.; Meyer, C.; Petrie, T. W.; Kahn, C.; Ejima, S.; D-III Physics Group

    1984-05-01

    The heat flux to the Doublet-III primary limiter has been monitored during plasma disruptions and during neutral beam injection. The surface temperature of the movable TiC-coated graphite limiter was measured with an Inframetrics thermal imaging system and a suitably filtered silicon photodiode spot detector. In addition, the floating electric potential of the limiter with respect to the vacuum vessel was measured. The heat pulse duration to the limiter was measured by the spot detector with a time response of ˜ 10 μs and these times were correlated with the plasma parameters. In limiter discharges, 20% of the plasma kinetic stored energy goes to the limiter during disruptions. The power balance during disruptions is also discussed. During neutral beam injection, the limiter is not heated uniformly; the ion drift side receives much more thermal flux than the electron drift side. The fraction of beam power going to the limiter is as high as ˜ 35% in normal limiter discharges.

  1. Effects of Flux and Energy of Neutral Beam on Hydrogenation of Graphene

    NASA Astrophysics Data System (ADS)

    Okada, Takeru; Samukawa, Seiji

    2015-09-01

    Hydrogen modification, hydrogenation, of graphene, has attracted due to the possibility of hydrogen storage. Chemisorbed hydrogen has strong interaction with graphene surface and sp3 bond forms. Surprisingly, ideal structure of graphene shows reversible absorption of hydrogen and it leads to effective designing of hydrogen storage material. In this paper, we have demonstrated neutral beam (NB) technique for hydrogenation of graphene instead of conventional plasma method. NB system consists of a plasma generation chamber and a process chamber, which are separated by a carbon plate with many apertures. The charged particles can be effectively neutralized by collision with the sidewall of the apertures when passing through them to the process chamber. Development of the D-band and blue shift of G-band were observed after hydrogen NB irradiation by Raman spectroscopy. FTIR analysis reveals CH bending mode was appeared and it depends on beam energy, thus CH formation has reaction threshold and potential to control it. In addition, it is shown that beam flux affects hydrogenation and additional effect is also included in reaction process. We believe our investigation will provide development of hydrogenated graphene applications.

  2. Off-axis Neutral Beam Current Drive for Advanced Scenario Development in DIII-D

    SciTech Connect

    Murakami, M; Park, J; Petty, C; Luce, T; Heidbrink, W; Osborne, T; Wade, M; Austin, M; Brooks, N; Budny, R; Challis, C; DeBoo, J; deGrassie, J; Ferron, J; Gohil, P; Hobirk, J; Holcomb, C; Hollmann, E; Hong, R; Hyatt, A; Lohr, J; Lanctot, M; Makowski, M; McCune, D; Politzer, P; Prater, R; John, H S; Suzuki, T; West, W; Unterberg, E; Van Zeeland, M; Yu, J

    2008-10-13

    Modification of the two existing DIII-D neutral beam lines is proposed to allow vertical steering to provide off-axis neutral beam current drive (NBCD) as far off-axis as half the plasma radius. New calculations indicate very good current drive with good localization off-axis as long as the toroidal magnetic field, B{sub T}, and the plasma current, I{sub p}, are in the same direction (for a beam steered downward). The effects of helicity can be large: e.g., ITER off-axis NBCD can be increased by more than 20% if the B{sub T} direction is reversed. This prediction has been tested by an off-axis NBCD experiment using reduced size plasmas that are vertically shifted with the existing NBI on DIII-D. The existence of off-axis NBCD is evident in sawtooth and internal inductance behavior. By shifting the plasma upward or downward, or by changing the sign of the toroidal field, measured off-axis NBCD profiles, determined from MSE data, are consistent with predicted differences (40%-45%) arising from the NBI orientation with respect to the magnetic field lines. Modification of the DIII-D NB system will strongly support scenario development for ITER and future tokamaks as well as providing flexible scientific tools for understanding transport, energetic particles and heating and current drive.

  3. A high-charge-state plasma neutralizer for an energetic H/sup -/ beam

    SciTech Connect

    Schlachter, A.S.; Leung, K.N.; Stearns, J.W.; Olson, R.E.

    1986-10-01

    A high-charge-state plasma neutralizer for a beam of energetic H/sup -/ ions offers the potential of high optimum neutralization efficiency (approx.85%) relative to a gas target (50 to 60%), and considerably reduced target thickness. We have calculated cross sections for charge-changing interactions of fast H/sup -/ and H/sup 0/ in collision with highly charged ions using a semiclassical model for H/sup -/, and the Classical-Trajectory Monte Carlo method plus Born calculations, to obtain correct asymptotic cross sections in the high-energy limit. Charge-state fractions as a function of plasma line density, and f/sub 0//sup max/, the maximum H/sup 0/ fraction, are calculated using these cross sections; we find that f/sub 0//sup mx/ approx. = 85% for ion charge states in the range 1+ to 10+, and that target ion line density for f/sub 0//sup max/ decreases approximately as the square of the plasma ion charge state. The maximum neutral fraction is also high for a partially ionized plasma. We have built a small multicusp plasma generator to use a a plasma neutralizer; preliminary results show that the plasma contains argon ions with an average charge state between 2+ and 3+ for a steady-state discharge.

  4. Development of a plasma generator for a long pulse ion source for neutral beam injectors

    SciTech Connect

    Watanabe, K.; Dairaku, M.; Tobari, H.; Kashiwagi, M.; Inoue, T.; Hanada, M.; Jeong, S. H.; Chang, D. H.; Kim, T. S.; Kim, B. R.; Seo, C. S.; Jin, J. T.; Lee, K. W.; In, S. R.; Oh, B. H.; Kim, J.; Bae, Y. S.

    2011-06-15

    A plasma generator for a long pulse H{sup +}/D{sup +} ion source has been developed. The plasma generator was designed to produce 65 A H{sup +}/D{sup +} beams at an energy of 120 keV from an ion extraction area of 12 cm in width and 45 cm in length. Configuration of the plasma generator is a multi-cusp bucket type with SmCo permanent magnets. Dimension of a plasma chamber is 25 cm in width, 59 cm in length, and 32.5 cm in depth. The plasma generator was designed and fabricated at Japan Atomic Energy Agency. Source plasma generation and beam extraction tests for hydrogen coupling with an accelerator of the KSTAR ion source have been performed at the KSTAR neutral beam test stand under the agreement of Japan-Korea collaborative experiment. Spatial uniformity of the source plasma at the extraction region was measured using Langmuir probes and {+-}7% of the deviation from an averaged ion saturation current density was obtained. A long pulse test of the plasma generation up to 200 s with an arc discharge power of 70 kW has been successfully demonstrated. The arc discharge power satisfies the requirement of the beam production for the KSTAR NBI. A 70 keV, 41 A, 5 s hydrogen ion beam has been extracted with a high arc efficiency of 0.9 -1.1 A/kW at a beam extraction experiment. A deuteron yield of 77% was measured even at a low beam current density of 73 mA/cm{sup 2}.

  5. Impurity levels and power loading in the PDX tokamak with high power neutral beam injection

    SciTech Connect

    Fonck, R.J.; Bell, M.; Bol, K.

    1982-10-01

    The PDX tokamak provides an experimental facility for the direct comparison of various impurity control techniques under reactor-like conditions. Four neutral beam lines can inject up to 6 MW for 300 ms. Carbon rail limiter discharges have been used to test the effectiveness of perpendicular injection, but non-disruptive full power operation for > 100 ms is difficult without extensive conditioning. Initial tests of a toroidal bumper limiter indicate reduced power loading and roughly similar impurity levels compared to the carbon rail limiter discharges. Poloidal divertor discharges with up to 5 MW of injected power are cleaner than similar circular discharges, and the power is deposited in a remote divertor chamber. High density divertor operation indicates a reduction of impurity flow velocity in the divertor and enhanced recycling in the divertor region during neutral injection.

  6. Diagnostic neutral beam injector and associated diagnostic systems for the TJ-II stellarator device

    NASA Astrophysics Data System (ADS)

    McCarthy, K. J.; Balbín, R.; López-Fraguas, A.; García, A.; Carmona, J. M.; Sánchez, J.; Ivanov, A. A.

    2004-10-01

    A diagnostic neutral beam injector, based on the DINA-5F injector, is under development for the highly flexible TJ-II stellarator. The principal goals are to obtain spatially resolved charge-exchange recombination spectroscopy and neutral particle analysis measurements along the plasma minor radius and to stimulate opportunities for new physics studies. We first summarize relevant TJ-II characteristics and the considerations addressed when defining this compact system, for instance, the steps taken to minimize the impact of ferromagnetic shielding on magnetic configurations. We then outline the main aspects of the system and associated diagnostics. In particular, we highlight a bidirectional fiber-optic based multichannel spectrometer for obtaining Doppler measurements with high spatial resolution.

  7. The Bootstrap Current and Neutral Beam Current Drive in DIII-D

    SciTech Connect

    Politzer, P.A.

    2005-10-15

    Noninductive current drive is an essential part of the implementation of the DIII-D Advanced Tokamak program. For an efficient steady-state tokamak reactor, the plasma must provide close to 100% bootstrap fraction (f{sub bs}). For noninductive operation of DIII-D, current drive by injection of energetic neutral beams [neutral beam current drive (NBCD)] is also important. DIII-D experiments have reached {approx}80% bootstrap current in stationary discharges without inductive current drive. The remaining current is {approx}20% NBCD. This is achieved at {beta}{sub N} [approximately equal to] {beta}{sub p} > 3, but at relatively high q{sub 95} ({approx}10). In lower q{sub 95} Advanced Tokamak plasmas, f{sub bs} {approx} 0.6 has been reached in essentially noninductive plasmas. The phenomenology of high {beta}{sub p} and {beta}{sub N} plasmas without current control is being studied. These plasmas display a relaxation oscillation involving repetitive formation and collapse of an internal transport barrier. The frequency and severity of these events increase with increasing {beta}, limiting the achievable average {beta} and causing modulation of the total current as well as the pressure. Modeling of both bootstrap and NBCD currents is based on neoclassical theory. Measurements of the total bootstrap and NBCD current agree with calculations. A recent experiment based on the evolution of the transient voltage profile after an L-H transition shows that the more recent bootstrap current models accurately describe the plasma behavior. The profiles and the parametric dependences of the local neutral beam-driven current density have not yet been compared with theory.

  8. Simulation of the neutral beam deposition within integrated tokamak modelling frameworks

    NASA Astrophysics Data System (ADS)

    Schneider, M.; Eriksson, L.-G.; Jenkins, I.; Artaud, J. F.; Basiuk, V.; Imbeaux, F.; Oikawa, T.; contributors, JET-EFDA; contributors, ITM-TF

    2011-06-01

    The NEMO (NEutral beam MOdelling) code for simulating neutral beam ionization during neutral beam injection (NBI) in tokamak plasmas has been developed for implementation in integrated modelling frameworks and is presented. Integrated modelling of fusion plasmas is becoming increasingly important, both for preparation and analysis of experiments in large devices. Moreover, it should play a crucial role for the design of future fusion reactors. In a modern context, integrated modelling requires codes that are (i) flexible in terms of their interfaces, i.e. can be adapted for different simulation environments, (ii) machine independent; i.e. they should not contain hard coded information on a particular device to be simulated; (iii) optimized for speed of execution, (iv) verified and validated. The NEMO code has been specially designed to meet these requirements. The code is based on the physics concept outlined by Feng et al (1995 Comput. Phys. Commun. 88 161-72) and is a completely modular program: it works with any input NBI geometry and can be coupled to any external Fokker-Planck calculation for evaluating the distribution function of the injected species, i.e. it can provide source terms for both Monte Carlo codes and codes using finite difference/elements methods. The NEMO code has already been integrated with the CRONOS integrated modelling suite (Artaud et al 2010 Nucl. Fusion 50 043001) and the European Integrated Tokamak Modelling Task Force (ITM-TF)b https://www.efda-itm.eu/index.html. The basics of the code are described in this paper along with an illustration of its integration in the ITM-TF simulation platform. A crucial aspect is the verification of the code, the results of benchmarks carried out with other NBI codes for JET and ITER discharges are thereby presented.

  9. Field reversed configuration confinement enhancement through edge biasing and neutral beam injection.

    PubMed

    Tuszewski, M; Smirnov, A; Thompson, M C; Korepanov, S; Akhmetov, T; Ivanov, A; Voskoboynikov, R; Schmitz, L; Barnes, D; Binderbauer, M W; Brown, R; Bui, D Q; Clary, R; Conroy, K D; Deng, B H; Dettrick, S A; Douglass, J D; Garate, E; Glass, F J; Gota, H; Guo, H Y; Gupta, D; Gupta, S; Kinley, J S; Knapp, K; Longman, A; Hollins, M; Li, X L; Luo, Y; Mendoza, R; Mok, Y; Necas, A; Primavera, S; Ruskov, E; Schroeder, J H; Sevier, L; Sibley, A; Song, Y; Sun, X; Trask, E; Van Drie, A D; Walters, J K; Wyman, M D

    2012-06-22

    Field reversed configurations (FRCs) with high confinement are obtained in the C-2 device by combining plasma gun edge biasing and neutral beam injection. The plasma gun creates an inward radial electric field that counters the usual FRC spin-up. The n = 2 rotational instability is stabilized without applying quadrupole magnetic fields. The FRCs are nearly axisymmetric, which enables fast ion confinement. The plasma gun also produces E × B shear in the FRC edge layer, which may explain the observed improved particle transport. The FRC confinement times are improved by factors 2 to 4, and the plasma lifetimes are extended from 1 to up to 4 ms.

  10. ProVac3D and Application to the Neutral Beam Injection System of ITER

    SciTech Connect

    Luo, X.; Dremel, M.; Day, Ch.

    2008-12-31

    In order to heat the confined plasma up to 100 million degrees Celsius and initiate a sustained fusion reaction, ITER will use several heating mechanisms at the same time, of which Neutral Beam Injection (NBI) systems play an important role. The NBI includes several internal gas sources and has to be operated under vacuum conditions. We have developed ProVac3D, a Monte Carlo simulation code, to calculate gas dynamics and the density profiles in volumes of interest inside NBI. This enables us to elaborate our in-situ and state-of-the-art cryogenic pump design and estimate the corresponding pumping speed.

  11. Design of Experimental Data Publishing Software for Neutral Beam Injector on EAST

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Hu, Chundong; Sheng, Peng; Zhao, Yuanzhe; Zhang, Xiaodan; Wu, Deyun

    2015-02-01

    Neutral Beam Injection (NBI) is one of the most effective means for plasma heating. Experimental Data Publishing Software (EDPS) is developed to publish experimental data to get the NBI system under remote monitoring. In this paper, the architecture and implementation of EDPS including the design of the communication module and web page display module are presented. EDPS is developed based on the Browser/Server (B/S) model, and works under the Linux operating system. Using the data source and communication mechanism of the NBI Control System (NBICS), EDPS publishes experimental data on the Internet.

  12. Observations of neutral beam and ICRF tail ion losses due to Alfven modes in TFTR

    SciTech Connect

    Darrow, D.S.; Zweben, S.J.; Chang, Z.

    1996-04-01

    Fast ion losses resulting from MHD modes at the Alfven frequency, such as the TAE, have been observed in TFTR. The modes have been driven both by neutral beam ions, at low B{sub T}, and by H-minority ICRF tail ions at higher B{sub T}. The measurements indicate that the loss rate varies linearly with the mode amplitude, and that the fast ion losses during the mode activity can be significant, e.g. up to 10% of the input power is lost in the worst case.

  13. Low damage etching method of low-k material with a neutral beam for interlayer dielectric of semiconductor device

    SciTech Connect

    Kang, Seung Hyun; Kim, Jong Kyu; Lee, Sung Ho; Kim, Jin Woo; Yeom, Geun Young

    2015-03-15

    To reduce the cross-talk between nanoscale devices, low-k materials such as methyl silsesquioxane (MSQ), which is damaged easily during plasma etching, are introduced as an intermetallic dielectric material in addition to the use of copper as the conducting material for the reduction of parasitic resistance and capacitance. In this study, beam techniques such as neutral/ion beams were used in the etching of MSQ and the effect of these beam techniques on the reduction of the degradation of the MSQ were investigated. When MSQ was etched using the same CF{sub 4} etch gas at the similar etch rate as that used for conventional MSQ etching using inductively coupled plasmas (ICPs), the neutral/ion beam etching showed lower F contents and lower penetration depth of F, indicating decreased degradation by fluorination of MSQ during etching using the beam techniques. Especially, the neutral beam etching technique showed the lowest F contamination and the lower penetration depth of F among the etch methods. When the dielectric constant was measured after the etching of the same depth, the MSQ etched with the neutral beam showed the lowest change of the dielectric constant, while that etched using the ICP showed the highest change of dielectric constant. The lower degradation, that is, the lower chemical modification of MSQ material with the beam technique is believed to be related to the decreased concentration of radical species in the processing chamber reacting with the MSQ surface, while the lowest degradation using the neutral beam is believed to be due to the lower reaction rate of the reactive neutral compared to reactive ions.

  14. Improved measurement of neutral current coherent $\\pi^0$ production on carbon in a few-GeV neutrino beam

    SciTech Connect

    Kurimoto, Y.; Alcaraz-Aunion, J.L.; Brice, S.J.; Bugel, L.; Catala-Perez, J.; Cheng, G.; Conrad, J.M.; Djurcic, Z.; Dore, U.; Finley, D.A.; Franke, A.J.; /Columbia U. /INFN, Rome

    2010-05-01

    The SciBooNE Collaboration reports a measurement of neutral current coherent neutral pion production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive neutral pion production has been improved by detecting recoil protons from resonant neutral pion production. We measure the ratio of the neutral current coherent neutral pion production to total charged current cross sections to be (1.16 +/- 0.24) x 10-2. The ratio of charged current coherent pion to neutral current coherent pion production is calculated to be 0.14+0.30 -0.28, using our published charged current coherent pion measurement.

  15. Current Control in ITER Steady State Plasmas With Neutral Beam Steering

    SciTech Connect

    R.V. Budny

    2009-09-10

    Predictions of quasi steady state DT plasmas in ITER are generated using the PTRANSP code. The plasma temperatures, densities, boundary shape, and total current (9 - 10 MA) anticipated for ITER steady state plasmas are specified. Current drive by negative ion neutral beam injection, lower-hybrid, and electron cyclotron resonance are calculated. Four modes of operation with different combinations of current drive are studied. For each mode, scans with the NNBI aimed at differing heights in the plasma are performed to study effects of current control on the q profile. The timeevolution of the currents and q are calculated to evaluate long duration transients. Quasi steady state, strongly reversed q profiles are predicted for some beam injection angles if the current drive and bootstrap currents are sufficiently large.

  16. Status of PRIMA, the test facility for ITER neutral beam injectors

    NASA Astrophysics Data System (ADS)

    Sonato, P.; Antoni, V.; Bigi, M.; Chitarin, G.; Luchetta, A.; Marcuzzi, D.; Pasqualotto, R.; Pomaro, N.; Serianni, G.; Toigo, V.; Zaccaria, P.; ITER International Team

    2013-02-01

    The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1MV a 40A beam of negative deuterons, delivering to the plasma about 17MW up to one hour. As these requirements have never been experimentally met, it was decided to build a test facility, PRIMA (Padova Research on ITER Megavolt Accelerator), in Italy, including a full-size negative ion source, SPIDER, and a prototype of the whole ITER injector, MITICA, aiming to develop the heating injectors to be installed in ITER. The Japan and the India Domestic Agencies participate in the PRIMA enterprise; European laboratories, such as KIT-Karlsruhe, IPP-Garching, CCFE-Culham, CEA-Cadarache and others are also cooperating. In the paper the main requirements are discussed and the design of the main components and systems are described.

  17. Ion beam transport: modelling and experimental measurements on a large negative ion source in view of the ITER heating neutral beam

    NASA Astrophysics Data System (ADS)

    Veltri, P.; Sartori, E.; Agostinetti, P.; Aprile, D.; Brombin, M.; Chitarin, G.; Fonnesu, N.; Ikeda, K.; Kisaki, M.; Nakano, H.; Pimazzoni, A.; Tsumori, K.; Serianni, G.

    2017-01-01

    Neutral beam injectors are among the most important methods of plasma heating in magnetic confinement fusion devices. The propagation of the negative ions, prior to their conversion into neutrals, is of fundamental importance in determining the properties of the beam, such as its aiming and focusing at long-distances, so as to deposit the beam power in the proper position inside the confined plasma, as well as to avoid interaction with the material surfaces along the beam path. The final design of the ITER Heating Neutral Beam prototype has been completed at Consorzio RFX (Padova, Italy), in the framework of a close collaboration with European, Japanese and Indian fusion research institutes. The physical and technical rationales on which the design is based were essentially driven by numerical modelling of the relevant physical processes, and the same models and codes will be useful to design the DEMO neutral beam injector in the near future. This contribution presents a benchmark study of the codes used for this purpose, by comparing their results against the measures performed in an existing large-power device, hosted at the National Institute for Fusion Science, Japan. In particular, the negative ion formation and acceleration are investigated. A satisfactory agreement was found between codes and experiments, leading to an improved understanding of beam transport dynamics. The interpretation of the discrepancies identified in previous works, possibly related to the non-uniformity of the extracted negative ion current, is also presented.

  18. Arcing and rf signal generation during target irradiation by a high-energy, pulsed neutral particle beam

    SciTech Connect

    Robiscoe, R.T.

    1988-02-01

    We present a theory describing the dynamics of arc discharges in bulk dielectric materials on board space-based vehicles. Such ''punch-through'' arcs can occur in target satellites irradiated by high-energy (250 MeV), pulsed (100 mA x 10 ms) neutral particle beams. We treat the arc as a capacitively limited avalanche current in the target dielectric material, and we find expressions for the arc duration, charge transport, currents, and discharge energy. These quantities are adjusted to be consistent with known scaling laws for the area of charge depleted by the arc. After a brief account of the statistical distribution of voltages at which the arc starts and stops, we calculate the signal strength and frequency spectrum of the electromagnetic radiation broadcast by the arc. We find that arcs from thick ()similarreverse arrowto)1 cm) targets can generate rf signals detectable up to 1000 km from the target, bu a radio receiver operating at frequency 80 MHz, bandwidth 100 kHz, and detection threshold -105 dBm. These thick-target arc signals are 10 to 20 dB above ambient noise at the receiver, and they provide target hit assessment if the signal spectrum can be sampled at several frequencies in the nominal range 30-200 MHz. Thin-target ()similarreverse arrowto)1 mm) arc signals are much weaker, but when they are detecable in conjunction with thick-target signals, target discrimination is possible by comparing the signal frequency spectra. 24 refs., 12 figs.

  19. Beams of fast neutral atoms and molecules in low-pressure gas-discharge plasma

    SciTech Connect

    Metel, A. S.

    2012-03-15

    Fast neutral atom and molecule beams have been studied, the beams being produced in a vacuum chamber at nitrogen, argon, or helium pressure of 0.1-10 Pa due to charge-exchange collisions of ions accelerated in the sheath between the glow discharge plasma and a negative grid immersed therein. From a flat grid, two broad beams of molecules with continuous distribution of their energy from zero up to e(U + U{sub c}) (where U is voltage between the grid and the vacuum chamber and U{sub c} is cathode fall of the discharge) are propagating in opposite directions. The beam propagating from the concave surface of a 0.2-m-diameter grid is focused within a 10-mm-diameter spot on the target surface. When a 0.2-m-diameter 0.2-m-high cylindrical grid covered by end disks and composed of parallel 1.5-mm-diameter knitting needles spaced by 4.5 mm is immersed in the plasma, the accelerated ions pass through the gaps between the needles, turn inside the grid into fast atoms or molecules, and escape from the grid through the gaps on its opposite side. The Doppler shift of spectral lines allows for measuring the fast atom energy, which corresponds to the potential difference between the plasma inside the chamber and the plasma produced as a result of charge-exchange collisions inside the cylindrical grid.

  20. Real-time control and data-acquisition system for high-energy neutral-beam injectors

    SciTech Connect

    Glad, A S; Jacobson, V

    1981-12-01

    The need for a real-time control system and a data acquisition, processing and archiving system operating in parallel on the same computer became a requirement on General Atomic's Doublet III fusion energy project with the addition of high energy neutral beam injectors. The data acquisition processing and archiving system is driven from external events and is sequenced through each experimental shot utilizing ModComp's intertask message service. This system processes, archives and displays on operator console CRTs all physics diagnostic data related to the neutral beam injectores such as temperature, beam alignment, etc. The real-time control system is data base driven and provides periodic monitoring and control of the numerous dynamic subsystems of the neutral beam injectors such as power supplies, timing, water cooling, etc.

  1. Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

    SciTech Connect

    Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; Startsev, Edward A.

    2012-05-31

    In this study, the design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ion driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B~100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasmaelectrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electrondynamics strongly affected by a weak applied magnetic field.

  2. Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

    DOE PAGES

    Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; ...

    2012-05-31

    In this study, the design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ionmore » driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B~100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasmaelectrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electrondynamics strongly affected by a weak applied magnetic field.« less

  3. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    NASA Astrophysics Data System (ADS)

    Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.; The DIII-D Team

    2017-01-01

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak (Luxon 2002 Nucl. Fusion 42 614). Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. Developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

  4. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    DOE PAGES

    Pace, D. C.; Collins, C. S.; Crowley, B.; ...

    2016-09-28

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significantmore » changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.« less

  5. Control of power, torque, and instability drive using in-shot variable neutral beam energy in tokamaks

    SciTech Connect

    Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.

    2016-09-28

    A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak. Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. As a result, developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.

  6. Current profile redistribution driven by neutral beam injection in a reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Parke, E.; Anderson, J. K.; Brower, D. L.; Den Hartog, D. J.; Ding, W. X.; Johnson, C. A.; Lin, L.

    2016-05-01

    Neutral beam injection in reversed-field pinch (RFP) plasmas on the Madison Symmetric Torus [Dexter et al., Fusion Sci. Technol. 19, 131 (1991)] drives current redistribution with increased on-axis current density but negligible net current drive. Internal fluctuations correlated with tearing modes are observed on multiple diagnostics; the behavior of tearing mode correlated structures is consistent with flattening of the safety factor profile. The first application of a parametrized model for island flattening to temperature fluctuations in an RFP allows inferrence of rational surface locations for multiple tearing modes. The m = 1, n = 6 mode is observed to shift inward by 1.1 ± 0.6 cm with neutral beam injection. Tearing mode rational surface measurements provide a strong constraint for equilibrium reconstruction, with an estimated reduction of q0 by 5% and an increase in on-axis current density of 8% ± 5%. The inferred on-axis current drive is consistent with estimates of fast ion density using TRANSP [Goldston et al., J. Comput. Phys. 43, 61 (1981)].

  7. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

    NASA Astrophysics Data System (ADS)

    Yamada, Masaaki

    2016-03-01

    This paper briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.

  8. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

    DOE PAGES

    Yamada, Masaaki

    2016-01-01

    This study briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactormore » program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.« less

  9. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

    SciTech Connect

    Yamada, Masaaki

    2016-01-01

    This study briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.

  10. Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

    SciTech Connect

    Yamada, Masaaki

    2016-03-25

    This paper briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.

  11. Current profile redistribution driven by neutral beam injection in a reversed-field pinch

    SciTech Connect

    Parke, E.; Anderson, J. K.; Den Hartog, D. J.; Brower, D. L.; Ding, W. X.; Lin, L.; Johnson, C. A.

    2016-05-15

    Neutral beam injection in reversed-field pinch (RFP) plasmas on the Madison Symmetric Torus [Dexter et al., Fusion Sci. Technol. 19, 131 (1991)] drives current redistribution with increased on-axis current density but negligible net current drive. Internal fluctuations correlated with tearing modes are observed on multiple diagnostics; the behavior of tearing mode correlated structures is consistent with flattening of the safety factor profile. The first application of a parametrized model for island flattening to temperature fluctuations in an RFP allows inferrence of rational surface locations for multiple tearing modes. The m = 1, n = 6 mode is observed to shift inward by 1.1 ± 0.6 cm with neutral beam injection. Tearing mode rational surface measurements provide a strong constraint for equilibrium reconstruction, with an estimated reduction of q{sub 0} by 5% and an increase in on-axis current density of 8% ± 5%. The inferred on-axis current drive is consistent with estimates of fast ion density using TRANSP [Goldston et al., J. Comput. Phys. 43, 61 (1981)].

  12. Measurement of transmission efficiency for 400 MeV proton beam through collimator at Fermilab MuCool Test Area using Chromox-6 scintillation screen

    NASA Astrophysics Data System (ADS)

    Jana, M. R.; Chung, M.; Freemire, B.; Hanlet, P.; Leonova, M.; Moretti, A.; Palmer, M.; Schwarz, T.; Tollestrup, A.; Torun, Y.; Yonehara, K.

    2013-06-01

    The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, feasibility studies of various types of RF cavities in a high magnetic field environment are in progress. As a unique approach, we have tested a RF cavity filled with a high pressure hydrogen gas with a 400 MeV proton beam in an external magnetic field (B = 3 T). Quantitative information about the number of protons passing through this cavity is an essential requirement of the beam test. The MTA is a flammable gas (hydrogen) hazard zone. Due to safety reasons, no active (energized) beam diagnostic instrument can be used. Moreover, when the magnetic field is on, current transformers (toroids) used for beam intensity measurements do not work due to the saturation of the ferrite material of the transformer. Based on these requirements, we have developed a passive beam diagnostic instrumentation using a combination of a Chromox-6 scintillation screen and CCD camera. This paper describes details of the beam profile and position obtained from the CCD image with B = 0 T and B = 3 T, and for high and low intensity proton beams. A comparison is made with beam size obtained from multi-wires detector. Beam transmission efficiency through a collimator with a 4 mm diameter hole is measured by the toroids and CCD image of the scintillation screen. Results show that the transmission efficiency estimated from the CCD image is consistent with the toroid measurement, which enables us to monitor the beam transmission efficiency even in a high magnetic field environment.

  13. Comparison of measured with calculated dose distribution from a 120-MeV electron beam from a laser-plasma accelerator.

    PubMed

    Lundh, O; Rechatin, C; Faure, J; Ben-Ismaïl, A; Lim, J; De Wagter, C; De Neve, W; Malka, V

    2012-06-01

    To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research. © 2012 American Association of Physicists in Medicine.

  14. Comparison of measured with calculated dose distribution from a 120-MeV electron beam from a laser-plasma accelerator

    SciTech Connect

    Lundh, O.; Rechatin, C.; Faure, J.; Ben-Ismaiel, A.; Lim, J.; De Wagter, C.; De Neve, W.; Malka, V.

    2012-06-15

    Purpose: To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. Methods: In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. Results: It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. Conclusions: The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research.

  15. Post-focus expansion of ion beams for low fluence and large area MeV ion irradiation: Application to human brain tissue and electronics devices

    NASA Astrophysics Data System (ADS)

    Whitlow, Harry J.; Guibert, Edouard; Jeanneret, Patrick; Homsy, Alexandra; Roth, Joy; Krause, Sven; Roux, Adrien; Eggermann, Emmanuel; Stoppini, Luc

    2017-08-01

    Irradiation with ∼3 MeV proton fluences of 106-109 protons cm-2 have been applied to study the effects on human brain tissue corresponding to single-cell irradiation doses and doses received by electronic components in low-Earth orbit. The low fluence irradiations were carried out using a proton microbeam with the post-focus expansion of the beam; a method developed by the group of Breese [1]. It was found from electrophysiological measurements that the mean neuronal frequency of human brain tissue decreased to zero as the dose increased to 0-1050 Gy. Enhancement-mode MOSFET transistors exhibited a 10% reduction in threshold voltage for 2.7 MeV proton doses of 10 Gy while a NPN bipolar transistor required ∼800 Gy to reduce the hfe by 10%, which is consistent the expected values.

  16. A Spectroscopic Study of Impurity Behavior in Neutral-beam and Ohmically Heated TFTR Discharges

    DOE R&D Accomplishments Database

    Stratton, B. C.; Ramsey, A. T.; Boody, F. P.; Bush, C. E.; Fonck, R. J.; Groenbner, R. J.; Hulse, R. A.; Richards, R. K.; Schivell, J.

    1987-02-01

    Quantitative spectroscopic measurements of Z{sub eff}, impurity densities, and radiated power losses have been made for ohmic- and neutral-beam-heated TFTR discharges at a plasma current of 2.2 MA and toroidal field of 4.7 T. Variations in these quantities with line-average plasma density (anti n{sub e}) and beam power up to 5.6 MW are presented for discharges on a graphite movable limiter. A detailed discussion of the use of an impurity transport model to infer absolute impurity densities and radiative losses from line intensity and visible continuum measurements is given. These discharges were dominated by low-Z impurities with carbon having a considerably higher density than oxygen, except in high-anti n{sub e} ohmic discharges, where the densities of carbon and oxygen were comparable. Metallic impurity concentrations and radiative losses were small, resulting in hollow radiated power profiles and fractions of the input power radiated being 30 to 50% for ohmic heating and 30% or less with beam heating. Spectroscopic estimates of the radiated power were in good agreement with bolometrically measured values. Due to an increase in the carbon density, Z{sub eff} rose from 2.0 to 2.8 as the beam power increased from 0 to 5.6 MW, pointing to a potentially serious dilution of the neutron-producing plasma ions as the beam power increased. Both the low-Z and metallic impurity concentrations were approximately constant with minor radius, indicating no central impurity accumulation in these discharges.

  17. Recent Progress in the Negative-Ion-Based Neutral Beam Injectors in Large Helical Device

    SciTech Connect

    Takeiri, Y.; Tsumori, K.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Oka, Y.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Kaneko, O.

    2009-03-12

    Negative-ion-based neutral beam injection (negative-NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to the improvement of the negative ion sources. Up to now, every injector achieves the designed injection energy and power of 180 keV-5 MW with hydrogen beams, and the total injection power exceeds 16 MW with three injectors. In the multi-round aperture grounded grid (GG), the diameter of a round aperture has been enlarged for higher GG transparency. Then, the GG heat load is reduced, as well as in the multi-slotted GG, and the voltage holding ability in the beam acceleration was improved. As a result, the beam energy is raised and the injection power is increased. To improve the anisotropic property of the beamlet convergence condition between the perpendicular and the parallel directions to the slots in the multi-slotted GG, a round-shape aperture of the steering grid (SG) has been changed to a racetrack shape. As a result, the difference of the beamlet conversion condition is much mitigated, and the injection efficiency (port-transmission efficiency) is improved, leading to 188 keV-6.4 MW injection. The Cs consumption is observed to be proportional to the tungsten evaporation from filaments. The Cs behavior is investigated with optical emission spectroscopy. During the beam extraction, the Cs recycling is dominated by Cs on the backplate, which is evaporated into the plasma by the backstreaming positive ions, and the wall surfaces should be loss regions for the supplied Cs.

  18. Recent Progress in the Negative-Ion-Based Neutral Beam Injectors in Large Helical Device

    NASA Astrophysics Data System (ADS)

    Takeiri, Y.; Tsumori, K.; Ikeda, K.; Osakabe, M.; Nagaoka, K.; Oka, Y.; Asano, E.; Kondo, T.; Sato, M.; Shibuya, M.; Komada, S.; Kaneko, O.

    2009-03-01

    Negative-ion-based neutral beam injection (negative-NBI) system has been operated for 10 years in Large Helical Device (LHD). The injection power has been increased year by year, according to the improvement of the negative ion sources. Up to now, every injector achieves the designed injection energy and power of 180 keV-5 MW with hydrogen beams, and the total injection power exceeds 16 MW with three injectors. In the multi-round aperture grounded grid (GG), the diameter of a round aperture has been enlarged for higher GG transparency. Then, the GG heat load is reduced, as well as in the multi-slotted GG, and the voltage holding ability in the beam acceleration was improved. As a result, the beam energy is raised and the injection power is increased. To improve the anisotropic property of the beamlet convergence condition between the perpendicular and the parallel directions to the slots in the multi-slotted GG, a round-shape aperture of the steering grid (SG) has been changed to a racetrack shape. As a result, the difference of the beamlet conversion condition is much mitigated, and the injection efficiency (port-transmission efficiency) is improved, leading to 188 keV-6.4 MW injection. The Cs consumption is observed to be proportional to the tungsten evaporation from filaments. The Cs behavior is investigated with optical emission spectroscopy. During the beam extraction, the Cs recycling is dominated by Cs on the backplate, which is evaporated into the plasma by the backstreaming positive ions, and the wall surfaces should be loss regions for the supplied Cs.

  19. Fast ion confinement and stability in a neutral beam injected reversed field pincha)

    NASA Astrophysics Data System (ADS)

    Anderson, J. K.; Almagri, A. F.; Den Hartog, D. J.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Mirnov, V. V.; Morton, L. A.; Nornberg, M. D.; Parke, E.; Reusch, J. A.; Sarff, J. S.; Waksman, J.; Belykh, V.; Davydenko, V. I.; Ivanov, A. A.; Polosatkin, S. V.; Tsidulko, Y. A.; Lin, L.; Liu, D.; Fiksel, G.; Sakakita, H.; Spong, D. A.; Titus, J.

    2013-05-01

    The behavior of energetic ions is fundamentally important in the study of fusion plasmas. While well-studied in tokamak, spherical torus, and stellarator plasmas, relatively little is known in reversed field pinch plasmas about the dynamics of fast ions and the effects they cause as a large population. These studies are now underway in the Madison Symmetric Torus with an intense 25 keV, 1 MW hydrogen neutral beam injector (NBI). Measurements of the time-resolved fast ion distribution via a high energy neutral particle analyzer, as well as beam-target neutron flux (when NBI fuel is doped with 3-5% D2) both demonstrate that at low concentration the fast ion population is consistent with classical slowing of the fast ions, negligible cross-field transport, and charge exchange as the dominant ion loss mechanism. A significant population of fast ions develops; simulations predict a super-Alfvénic ion density of up to 25% of the electron density with both a significant velocity space gradient and a sharp radial density gradient. There are several effects on the background plasma including enhanced toroidal rotation, electron heating, and an altered current density profile. The abundant fast particles affect the plasma stability. Fast ions at the island of the core-most resonant tearing mode have a stabilizing effect, and up to 60% reduction in the magnetic fluctuation amplitude is observed during NBI. The sharp reduction in amplitude, however, has little effect on the underlying magnetic island structure. Simultaneously, beam driven instabilities are observed as repetitive ˜50 μs bursts which coincide with fast particle redistribution; data indicate a saturated core fast ion density well below purely classical predictions.

  20. Fast ion confinement and stability in a neutral beam injected reversed field pinch

    SciTech Connect

    Anderson, J. K.; Almagri, A. F.; Den Hartog, D. J.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Mirnov, V. V.; Morton, L. A.; Nornberg, M. D.; Parke, E.; Reusch, J. A.; Sarff, J. S.; Waksman, J.; Belykh, V.; Davydenko, V. I.; Ivanov, A. A.; Polosatkin, S. V.; Tsidulko, Y. A.; Lin, L.; Liu, D.; and others

    2013-05-15

    The behavior of energetic ions is fundamentally important in the study of fusion plasmas. While well-studied in tokamak, spherical torus, and stellarator plasmas, relatively little is known in reversed field pinch plasmas about the dynamics of fast ions and the effects they cause as a large population. These studies are now underway in the Madison Symmetric Torus with an intense 25 keV, 1 MW hydrogen neutral beam injector (NBI). Measurements of the time-resolved fast ion distribution via a high energy neutral particle analyzer, as well as beam-target neutron flux (when NBI fuel is doped with 3–5% D{sub 2}) both demonstrate that at low concentration the fast ion population is consistent with classical slowing of the fast ions, negligible cross-field transport, and charge exchange as the dominant ion loss mechanism. A significant population of fast ions develops; simulations predict a super-Alfvénic ion density of up to 25% of the electron density with both a significant velocity space gradient and a sharp radial density gradient. There are several effects on the background plasma including enhanced toroidal rotation, electron heating, and an altered current density profile. The abundant fast particles affect the plasma stability. Fast ions at the island of the core-most resonant tearing mode have a stabilizing effect, and up to 60% reduction in the magnetic fluctuation amplitude is observed during NBI. The sharp reduction in amplitude, however, has little effect on the underlying magnetic island structure. Simultaneously, beam driven instabilities are observed as repetitive ∼50 μs bursts which coincide with fast particle redistribution; data indicate a saturated core fast ion density well below purely classical predictions.