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Sample records for mev neutral beam

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    The H- magnetron source provides about 100 mA H- beam to be match into the radio-frequency quadrupole accelerator. As H- 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- 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- beam from optically pumped polarized ion source.

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

    PubMed

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

    2016-02-01

    The H(-) magnetron source provides about 100 mA H(-) beam to be match into the radio-frequency quadrupole accelerator. As H(-) 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(-) 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(-) beam from optically pumped polarized ion source. PMID:26932107

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

    PubMed

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

    2016-02-01

    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. PMID:26932016

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  5. Charge steering of laser plasma accelerated fast ions in a liquid spray — creation of MeV negative ion and neutral atom beams

    SciTech Connect

    Schnürer, M.; Abicht, F.; Priebe, G.; Braenzel, J.; Prasad, R.; Borghesi, M.; Andreev, A.; Nickles, P. V.; Jequier, S.; Tikhonchuk, V.; Ter-Avetisyan, S.

    2013-11-15

    The scenario of “electron capture and loss” has been recently proposed for the formation of negative ion and neutral atom beams with up to MeV kinetic energy [S. Ter-Avetisyan, et al., Appl. Phys. Lett. 99, 051501 (2011)]. Validation of these processes and of their generic nature is here provided in experiments where the ion source and the interaction medium have been spatially separated. Fast positive ions accelerated from a laser plasma source are sent through a cold spray where their charge is changed. Such formed neutral atom or negative ion has nearly the same momentum as the original positive ion. Experiments are released for protons, carbon, and oxygen ions and corresponding beams of negative ions and neutral atoms have been obtained. The electron capture and loss phenomenon is confirmed to be the origin of the negative ion and neutral atom beams. The equilibrium ratios of different charge components and cross sections have been measured. Our method is general and allows the creation of beams of neutral atoms and negative ions for different species which inherit the characteristics of the positive ion source.

  6. Neutral beam monitoring

    DOEpatents

    Fink, Joel H.

    1981-08-18

    Method and apparatus for monitoring characteristics of a high energy neutral beam. A neutral beam is generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange neutralizes the high energy ion beam. The neutral beam is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are further identified.

  7. 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.

  8. Neutral beam development plan

    SciTech Connect

    Staten, H S

    1980-08-01

    The national plan is presented for developing advanced injection systems for use on upgrades of existing experiments, and use on future facilities such as ETF, to be built in the late 1980's or early 90's where power production from magnetic fusion will move closer to a reality. Not only must higher power and longer pulse length systems be developed , but they must operate reliably; they must be a tool for the experimenter, not the experiment itself. Neutral beam systems handle large amounts of energy and as such, they often are as complicated as the plasma physics experiment itself. This presents a significant challenge to the neutral beam developer.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  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. Fast ion profiles during neutral beam and lower hybrid heating

    SciTech Connect

    Heidbrink, W.W.; Strachan, J.D.; Bell, R.E.; Cavallo, A.; Motley, R.; Schilling, G.; Stevens, J.; Wilson, J.R.

    1985-07-01

    Profiles of the d(d,p)t fusion reaction are measured in the PLT tokamak using an array of collimated 3 MeV proton detectors. During deuterium neutral beam injection, the emission profile indicates that the beam deposition is at least as narrow as predicted by a bounce-averaged Fokker-Planck code. The fast ion tail formed by lower hybrid waves (at densities above the critical density for current drive) also peaks strongly near the magnetic axis.

  20. 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.

  1. 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.

  2. 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.

  3. Neutral Beam Ion Confinement in NSTX

    SciTech Connect

    D.S. Darrow; E.D. Fredrickson; S.M. Kaye; S.S. Medley; and A.L. Roquemore

    2001-07-24

    Neutral-beam (NB) heating in the National Spherical Torus Experiment (NSTX) began in September 2000 using up to 5 MW of 80 keV deuterium (D) beams. An initial assessment of beam ion confinement has been made using neutron detectors, a neutral particle analyzer (NPA), and a Faraday cup beam ion loss probe. Preliminary neutron results indicate that confinement may be roughly classical in quiescent discharges, but the probe measurements do not match a classical loss model. MHD activity, especially reconnection events (REs) causes substantial disturbance of the beam ion population.

  4. Neutral particle beam scoring system proof-of-principle experiment

    SciTech Connect

    Tichenor, D.A.; Pontau, A.E.; Antolak, A.J.

    1986-10-01

    A method of scoring a ground-based neutral particle beam pointing experiment is described. Beam scoring in this context means performing beam direction measurements in the near field (tens of meters) sufficient to determine whether energy would be concentrated on a far-field target as desired in a pointing experiment. The principle of operation is to impress a high-resolution spatial modulation on the beam by inserting an array of shadow wires into the beam upstream of the steering magnet. At the downstream end of the beam line the shadows are detected using one or more scintillation screens and video cameras. Beam direction is determined by measuring the location of the shadows at a known distance downstream of the point of steering. A proof-of-principle experiment demonstrates that: (1) wire shadows can be created in a 50 MeV beam and propagate over the distances required; (2) images of sufficient brightness and resolution can be formed on scintillating screens excited by 50 MeV protons; and (3) CCD array cameras can operate in the radiation environment created near the beam line.

  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

    SciTech Connect

    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. Focusing and neutralization of intense beams

    SciTech Connect

    Yu, Simon S.; Anders, Andre; Bieniosek, F.M.; Eylon, Shmuel; Henestroza, Enrique; Roy, Prabir; Shuman, Derek; Waldron, William; Sharp, William; Rose, Dave; Welch, Dale; Efthimion, Philip; Gilson, Eric

    2003-05-01

    In heavy ion inertial confinement fusion systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. Effective plasma neutralization of intense ion beams through the target chamber is essential for the viability of an economically competitive heavy ion fusion power plant. The physics of neutralized drift has been studied extensively with PIC simulations. To provide quantitative comparisons of theoretical predictions with experiment, the Heavy Ion Fusion Virtual National Laboratory has completed the construction and has begun experimentation with the NTX (Neutralized Transport Experiment) as shown in Figure 1. The experiment consists of 3 phases, each with physics issues of its own. Phase 1 is designed to generate a very high brightness potassium beam with variable perveance, using a beam aperturing technique. Phase 2 consists of magnetic transport through four pulsed quadrupoles. Here, beam tuning as well as the effects of phase space dilution through higher order nonlinear fields must be understood. In Phase 3, a converging ion beam at the exit of the magnetic section is transported through a drift section with plasma sources for beam neutralization, and the final spot size is measured under various conditions of neutralization. In this paper, we present first results from all 3 phases of the experiment.

  9. 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.

  10. Neutralized transport of high intensity beams

    SciTech Connect

    Henestroza, E.; Yu, S.S.; Eylon, S.; Roy, P.K.; Anders, A.; Sharp, W.; Efthimion, P.; Gilson, E.; Welch, D.; Rose, D.

    2003-05-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. A converging ion beam at the exit of the final focus magnetic system is injected into a neutralized drift section. The neutralization is provided by a metal arc source and an RF plasma source. Effects of a ''plasma plug'', where electrons are extracted from a localized plasma in the upstream end of the drift section, and are then dragged along by the ion potential, as well as the ''volumetric plasma'', where neutralization is provided by the plasma laid down along the ion path, are both studied and their relative effects on the beam spot size are compared. Comparisons with 3-D PIC code predictions will also be presented.

  11. 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.

  12. The 50 MeV Beam Test Facility at LBL

    SciTech Connect

    Leemans, W.; Behrsing, G.; Kim, K.J.; Krupnick, J.; Matuk, C.; Selph, F.; Chattopadhyay, S.

    1993-05-01

    A new beam line, expected to be built by September 1993, will transport the 50 MeV electron beam from the ALS LINAC into an experimental area to support various R&D activities in the Center for Beam Physics at LBL. A variety of experiments are planned involving the interaction of such a relativistic electron beam with plasmas (plasma focusing), laser beams (generation of femtosecond X-ray pulses) and electromagnetic cavities (Crab cavities etc....). The beam line is designed using the measured emittance and Twiss parameters of the ALS linac. It accommodates the different requirements of the various experiments on the electron beam properties (charge, energy, pulse length) and on the handling of the beam before and after the interaction point. Special attention has also been given to incorporate diagnostics for measuring the beam properties (such as the electron energy, bunch length and charge) needed in the interpretation of the experiments.

  13. 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. PMID:18315236

  14. 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.

  15. Numerical study of beam propagation and plasma properties in the neutralizer and the E-RID of the ITER Neutral Beam Injector

    NASA Astrophysics Data System (ADS)

    Lifschitz, A. F.; Revel, A.; Caillault, L.; Minea, T.

    2014-04-01

    Non-ohmic heating will be used in the experimental nuclear fusion reactor ITER to reach thermonuclear temperatures. Two heating mechanism will be implemented, i.e. microwaves resonant with ion and electron cyclotron frequencies and energetic neutral beam injection, which contributes also to the current drive. Each one of the two neutral beam injector planned for ITER will deliver 16 MW of 1 MeV D0 beam. In the injector, negative ions D- coming from a 40 A negative ion source are electrostatically accelerated to 1 MeV, and stripped of their extra electron by collision with a target gas in a structure known as the neutralizer. Residual charged particles are deflected after the neutralizer in an electrostatic ion dump (E-RID). The ionization of the deuterium buffer gas filling the neutralizer induced by the D- beam creates a rarefied plasma which is expected to efficiently screens the Coulomb repulsion of the beam. Moreover, this plasma can eventually escape from the neutralizer and move back in the accelerator, towards the accelerating grids and the negative ion source. The transport of the beam through the neutralizer and the RID and the related plasma properties were studied using a 3D electrostatic particle-in-cell code called OBI-3 (Orsay Beam Injector 3 dimensional). Particle-particle and particle-wall collisions are treated using the Monte Carlo collision approach. Simulations show that the secondary plasma effectively screens the beam space charge preventing beam transverse expansion. Plasma ions created in the neutralizer form an upstream current with a magnitude of ˜0.5% of the negative ion current. Gas breakdown leading to arc formation in the RID was not observed. Finally, results for the propagation of non-ideal beams coming from simulations of the extraction and consecutive acceleration taken from Revel et al 2013 Nucl. Fusion 53 073027 are presented.

  16. Long pulse H- ion beam acceleration in MeV accelerator.

    PubMed

    Taniguchi, M; Mizuno, T; Umeda, N; Kashiwagi, M; Watanabe, K; Tobari, H; Kojima, A; Tanaka, Y; Dairaku, M; Hanada, M; Sakamoto, K; Inoue, T

    2010-02-01

    A multiaperture multigrid accelerator called "MeV accelerator" has been developed for neutral beam injection system of international thermonuclear experimental reactor. In the present work, long pulse H(-) ion beam acceleration was performed by the MeV accelerator equipped with new water-cooled grids. At present, the pulse length was extended to 5 s for the beams of 750 keV, 221 mA, and 10 s for the beams of 600 keV, 158 mA. Energy density, defined as products of beam energy (keV), current (mA), and pulse (s) divided by aperture area (m(2)), increased more than one order of magnitude higher compared with original MeV accelerator without water cooling in its grids. At higher energy and current, the grid was melted by beam deflection. Due to this grid melting, breakdowns occurred between the grids, and hence, the pulse length was limited. Beam deflection will be compensated by aperture displacement in next experiment. PMID:20192408

  17. 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. PMID:26520957

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Particle reflection and TFTR neutral beam diagnostics

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kugel, H.W.; O`Connor, T.E.; Newman, R.A.; Stevenson, T.N.; von Halle, A.; Williams, M.D.

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a ``V``-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the ``V``, complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

  5. Particle reflection and TFTR neutral beam diagnostics

    SciTech Connect

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

    1992-04-01

    Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12{degrees}). Beamline calorimeters, of a V''-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the V'', complicating the fitting technique, and increasing the power density on axis by 10 to 20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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.

  8. Doppler-shifted neutral beam line shape and beam transmission

    SciTech Connect

    Kamperschroer, J.H.; Grisham, L.R.; Kokatnur, N.; Lagin, L.J.; Newman, R.A.; O`Connor, T.E.; Stevenson, T.N.; von Halle, A.

    1994-04-01

    Analysis of Doppler-shifted Balmer-{alpha} line emission from the TFTR neutral beam injection systems has revealed that the line shape is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the broad portion of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e- divergence of 1.3{degrees} (based on fits to the beam shape on the calorimeter), the broad part has a divergence of 6.9{degrees}. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9{degrees}. Up to now, fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of {approximately}75%, a value in rough agreement with predictions of the Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An average angle of incidence for beam loss at the exit of the neutralizer is 2.2{degrees}, rather than the 4.95{degrees} subtended by the center of the ion source. This average angle of incidence, which is used in computing power densities on collimators, is shown to be a function of beam divergence.

  9. 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.

  10. 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.

  11. Plasma heating with multi-MeV neutral impurity beams

    SciTech Connect

    Grisham, L.R.; Post, D.E.; Eubank, H.P.; Firestone, M.; Mikkelsen, D.R.; Singer, C.E.; Weisheit, J.

    1981-03-01

    The utility of neutral beams of A greater than or equal to 6 AMU formed from negative ions, accelerated to approx. 1 MeV/AMU and neutralized, is explored for heating toroidally confined plasmas. Such beams offer the promise of significant advantages relative to conventional neutral beams based upon positive or negative hydrogen ions at 100 to 200 keV/AMU.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  13. 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.

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

    SciTech Connect

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

    2012-02-15

    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.

  15. 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.

  16. 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.

  17. Neutral-beam development plan, FY 1982-1987

    SciTech Connect

    Not Available

    1981-09-01

    The following chapters are included: (1) status of BNL negative ion source development, (2) source development program plan, (3) status of beam transport and acceleration, (4) accelerator development program plan, (5) neutralizer concepts, (6) neutralization program plan, (7) neutral beam systems, (8) test facilities, (9) program milestones and time schedules, (10) organization and Grumman participation, and (11) funding tables. (MOW)

  18. 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.

  19. 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.

  20. 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.

  1. Negative hydrogen ion source for TOKAMAK neutral beam injector (invited)

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Fujiwara, Y.; Kashiwagi, M.; Kitagawa, T.; Miyamoto, K.; Morishita, T.; Hanada, M.; Takayanagi, T.; Taniguchi, M.; Watanabe, K.

    2000-02-01

    Intense negative ion source producing multimegawatt hydrogen/deuterium negative ion beams has been developed for the neutral beam injector (NBI) in TOKAMAK thermonuclear fusion machines. Negative ions are produced in a cesium seeded multi-cusp plasma generator via volume and surface processes, and accelerated with a multistage electrostatic accelerator. The negative ion source for JT-60U has produced 18.5 A/360 keV (6.7 MW) H- and 14.3 A/380 keV (5.4 MW) D- ion beams at average current densities of 11 mA/cm2 (H-) and 8.5 mA/cm2 (D-). A high energy negative ion source has been developed for the next generation TOKAMAK such as the International Thermonuclear Experimental Reactor (ITER). The source has demonstrated to accelerate negative ions up to 1 MeV, the energy required for ITER. Higher negative ion current density of more than 20 mA/cm2 was obtained in the ITER concept sources. It was confirmed that the consumption rate of cesium is small enough to operate the source for a half year in ITER-NBI without maintenance.

  2. 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.

  3. 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.

  4. 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/.

  5. 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.

  6. 5MeV Electron Beam Facilities in Japan

    NASA Astrophysics Data System (ADS)

    Mizusawa, K.; Kashiwagi, M.; Hoshi, Y.

    1998-06-01

    There are 3 facilities with 5MeV electron beam processing machines in Japan and another one is planned to start operation in 1998. 2 of them are installed by Nissin-High Voltage and the other are by Sumitomo Heavy/Radiation Dynamics. In this report are introduced 2 facilities which we have installed and are operating satisfactorily. The first one was: installed at Radia Industry for irradiation services and the second one for in-house use in a factory of a pharmaceutical plastic container manufacturer, Shinko Chemical. And the second one is available for contract irradiation. The machine in Radia Industry has a comprehensive conveyor system with a turn-over equipment to shoot from the top and the bottom of materials with e-beam and X-ray, and has been successfully operated for many years. The machine in Shinko Chemical is equipped with a unique conveyor system with two conveyor lines under the beam window and the motion of the lines are opposite each other. This conveyor system also has a turn-over equipment like other machines but the direction of turning-over is designed to give the irradiated materials more uniform dose.

  7. Neutral beam dump with cathodic arc titanium gettering

    SciTech Connect

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

    2011-03-15

    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 x 10{sup 17} H/(cm{sup 2}s) 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 {approx}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.

  8. Requirements for neutral beam current drive in tokamaks

    SciTech Connect

    Dory, R.A.

    1988-01-01

    This paper contains viewgraphs on the use of neutral beam current drive in future tokamaks. Current profiles, slowing down distributions, beam destabilization of alfven waves and plasma parameters are some items covered in this paper. (DWL)

  9. 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.

  10. Neutral Beam Ion Loss Modelling for NSTX

    NASA Astrophysics Data System (ADS)

    Darrow, D. S.; Akers, R.; Kaye, S. M.; Mikkelsen, D. R.

    1999-11-01

    The loss of 80 keV D neutral beam ions to the walls has been modeled for a range of plasma conditions in NSTX using the EIGOL code[1]. Initial results of the code are in reasonable agreement with those from the LOCUST code[2]. Both codes predict loss fractions of 20% for a discharge with β_T=40% and q_0=2.6. Losses are strongly concentrated on the front face and edges of the high-harmonic fast wave antenna as it projects farther inward than other internal structures at the midplane. The edges of the passive stabilizer plates near the midplane are also subject to a large flux of lost beam ions under some conditions. The dependence of the loss upon the plasma density profile, I_p, and BT will be presented. [1] D. S. Darrow, et al., in Proceedings of the 26th EPS Conference on Controlled Fusion and Plasma Physics, Maastricht, The Netherlands, 14-18 June 1999. [2] R. Akers, et al., ibid.

  11. Conceptual Design of Neutral Beam Injection System for EAST

    NASA Astrophysics Data System (ADS)

    Hu, Chundong; NBI Team

    2012-06-01

    Neutral beam injection (NBI) system with two neutral beam injections will be constructed on the Experimental Advanced Superconducting Tokamak (EAST) in two stages for high power auxiliary plasmas heating and non-inductive current drive. Each NBI can deliver 2~4 MW beam power with 50~80 keV beam energy in 10~100 s pulse length. Each elements of the NBI system are presented in this contribution.

  12. RAMI Analyses of Heating Neutral Beam and Diagnostic Neutral Beam Systems for ITER

    NASA Astrophysics Data System (ADS)

    Chang, D. H.; Lee, S.; Hemsworth, R.; van Houtte, D.; Okayama, K.; Sagot, F.; Schunke, B.; Svensson, L.

    2011-09-01

    A RAMI (Reliability, Availability, Maintainability, Inspectability) analysis has been performed for the heating (& current drive) neutral beam (HNB) and diagnostic neutral beam (DNB) systems of the ITER device [1-3]. The objective of these analyses is to implement RAMI engineering requirements for design and testing to prepare a reliability-centred plan for commissioning, operation, and maintenance of the system in the framework of technical risk control to support the overall ITER Project. These RAMI requirements will correspond to the RAMI targets for the ITER project and the compensating provisions to reach them as deduced from the necessary actions to decrease the risk level of the function failure modes. The RAMI analyses results have to match with the procurement plan of the systems.

  13. Long pulse acceleration of MeV class high power density negative H- ion beam for ITER

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    R&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- ion beam acceleration up to 1 MeV with 200 A/m2 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/m2 of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  14. 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.

  15. Gas Flow Measurements of a Novel Geometry for Neutral Beam Neutralizers.

    NASA Astrophysics Data System (ADS)

    Pirkle, David Ross

    The gas flow characteristics of a novel geometry (pumped neutralizer) for decreasing the flow of gas from neutral beam neutralizers were measured and compared with a conventional (passive) neutralizer. A passive neutralizer is typically a duct attached to the ion source. For the pumped neutralizer the top and bottom surfaces of the duct are replaced by a Venetian blind geometry which opens into ballast vacuum pumping volumes. With guidance from a Monte Carlo program which models gas flow at low pressure, a one-half scale model with pumped neutralizer geometry was built and compared to a passive neutralizer with comparable dimensions. With the vanes on the pumped neutralizer opened to 55 degrees, the line density of the pumped neutralizer was 1.6 times less than the passive neutralizer. The amount of gas flowing from the exit of the pumped neutralizer was from 2 to 5 times less than the amount flowing from the pumped neutralizer. Hence, the pumped neutralizer geometry appears to be a promising method of limiting the flow of gas from neutral beam gas cell neutralizers.

  16. Radiation Safety System for SPIDER Neutral Beam Accelerator

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Charge-exchange neutral particle measurement in MeV energy range on JT-60U

    NASA Astrophysics Data System (ADS)

    Kusama, Y.; Nemoto, M.; Satoh, M.; Tsukahara, Y.; Tobita, K.; Takeuchi, H.; Petrov, S.; Afanassiev, V.; Kozlovskij, S.; Kislyakov, A.; Petrov, M.

    1995-01-01

    A charge-exchange neutral particle analyzer for the measurement of the MeV energy range ions produced by nuclear fusion or radio frequency heating has been developed and installed in JT-60U. Neutral particles entering the analyzer are ionized with a carbon foil of thickness 400 Å. The energy and mass of the stripped ions are resolved by magnetic and electrostatic fields (E∥B type). The analyzer has eight CsI(Tl) scintillator detectors. The energy range is 0.5-4 MeV for 4He0, the dynamic range is 4.08 and the energy resolution is 6%-11%. The detection efficiency for 4He0 with energy above 1 MeV is 30%-40%. A pulse height analysis (PHA) with 16 channels was adopted to distinguish particle signals from noise arising from neutrons, γ rays and optical lights emitted by JT-60U plasmas. The validity of the PHA was confirmed in a calibration experiment using a neutron source and in a high power heating experiment in JT-60U.

  2. 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.

  3. Space Charge Neutralization in the ITER Negative Ion Beams

    SciTech Connect

    Surrey, Elizabeth

    2007-08-10

    A model of the space charge neutralization of negative ion beams, developed from the model due to Holmes, is applied to the ITER heating and diagnostic beams. The Holmes model assumed that the plasma electron temperature was derived from the stripped electrons. This is shown to be incorrect for the ITER beams and the plasma electron temperature is obtained from the average creation energy upon ionization. The model shows that both ITER beams will be fully space charge compensated in the drift distance between the accelerator and the neutralizer. Inside the neutralizer, the plasma over compensates the space charge to the extent that a significant focusing force is predicted. At a certain position in the neutraliser this force balances the defocusing force due to the ions' transverse energy. Under these conditions the beam distribution function can change from Gaussian to Bennett and evidence of such a distribution observed in a multi-aperture, neutralized negative ion beam is presented.

  4. Neutral beam processing of semiconductor materials

    SciTech Connect

    Cross, J.; Hoffbauer, M.

    1996-09-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The most important challenge facing the US and global microelectronics industry is to identify and develop the next generation of processing technology to produce device structures with dimensions substantially less than 0.25 microns. This project sought to develop controlled, contamination-free etching techniques that are more selective and less damaging than current methods, which are based on inducing surface chemical reactions by rather crude ion-damage mechanisms. The use of non-charged particle etching and cleaning processes in the production of memory and microprocessor chips has been identified by The National Technology Roadmap for Semiconductors as a new manufacturing technique that may aid in the quest for feature sizes of 0.1 micron and lower. The Hyperthermal Neutral Beam Facility at Los Alamos has demonstrated significant improvement over ion-assisted etching in experiments using energetic oxygen and chlorine atoms.

  5. 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.

  6. Neutral-beam systems for magnetic-fusion reactors

    SciTech Connect

    Fink, J. H.

    1981-08-10

    Neutral beams for magnetic fusion reactors are at an early stage of development, and require considerable effort to make them into the large, reliable, and efficient systems needed for future power plants. To optimize their performance to establish specific goals for component development, systematic analysis of the beamlines is essential. Three ion source characteristics are discussed: arc-cathode life, gas efficiency, and beam divergence, and their significance in a high-energy neutral-beam system is evaluated.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. A microwave plasma cathode electron gun for ion beam neutralization

    NASA Astrophysics Data System (ADS)

    Fusellier, C.; Wartski, L.; Aubert, J.; Schwebel, C.; Coste, Ph.; Chabrier, A.

    1998-02-01

    It is well known that there exist two distinct types of ion beam neutralization, viz., charge and current neutralization. We have designed and studied a versatile and compact microwave plasma (MP) cathode electron gun dedicated to charge as well as current neutralization. Unlike the conventional hot cathode neutralizer, this MP cathode allows operation of the electron gun in a reactive gaseous environment when it is eventually associated with an electron cyclotron resonance (ECR) ion gun. Charge neutralization can be easily carried out by extracting from the MP cathode through a 1 mm diameter hole, a 35 mA electron beam under a 20 V voltage; the MP cathode being fed with a 75 W microwave power at 2.45 GHz. Higher beam intensities could be obtained using a multiaperture thin plate. Electron beam intensities as high as 300 mA and energies of 2 keV needed for current neutralization, e.g., when an ion beam impinges onto a thick dielectric surface, are obtained via a two-stage arrangement including an anodic chamber associated with a set of three monoaperture plates for the electron beam extraction. Transport of 200-2000 eV electron beams is ensured using focusing optics composed of three aligned tubes 6 cm in diameter and unsymmetrically polarized.

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

    NASA Astrophysics Data System (ADS)

    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.

    2016-02-01

    The ITER baseline foresees 2 Heating Neutral Beams (HNB's) based on 1 MeV 40 A D- 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 H0 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.

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

    PubMed

    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

    2016-02-01

    The ITER baseline foresees 2 Heating Neutral Beams (HNB's) based on 1 MeV 40 A D(-) 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(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. PMID:26932111

  15. Neutralization of a fast negative-ion beam

    SciTech Connect

    Schlachter, A.S.; Mowat, J.R.; Stearns, J.W.; Gohil, P.; Pyle, R.V.

    1986-01-01

    Neutralization of a fast negative-ion beam, primarily H/sup -/, is discussed in terms of competing one- and two-electron detachment processes in a variety of media: gas (vapor), plasma, liquid sheet, solid foil.

  16. Automation of neutral beam source conditioning with artificial intelligence techniques

    SciTech Connect

    Johnson, R.R.; Canales, T.W.; Lager, D.L.

    1985-01-01

    This paper describes a system that automates neutral beam source conditioning. The system achieves this with artificial intelligence techniques. The architecture of the system is presented followed by a description of its performance.

  17. Calculation of neutral beam deposition accounting for excited states

    SciTech Connect

    Gianakon, T.A.

    1992-09-01

    Large-scale neutral-beam auxillary heating of plasmas has led to new plasma operational regimes which are often dominated by fast ions injected via the absorption of an energetic beam of hydrogen neutrals. An accurate simulation of the slowing down and transport of these fast ions requires an intimate knowledge of the hydrogenic neutral deposition on each flux surface of the plasma. As a refinement to the present generation of transport codes, which base their beam deposition on ground-state reaction rates, a new set of routines, based on the excited states of hydrogen, is presented as mechanism for computing the attenuation and deposition of a beam of energetic neutrals. Additionally, the numerical formulations for the underlying atomic physics for hydrogen impacting on the constiuent plasma species is developed and compiled as a numerical database. Sample results based on this excited state model are compared with the ground-state model for simple plasma configurations.

  18. Neutral beam species measurements using in situ Rutherford backscatter spectrometry

    SciTech Connect

    Kugel, H.W.; Kaita, R.; Gammel, G.; Williams, M.D.

    1984-12-01

    This work describes a new in situ method for measuring the neutral particle fractions in high power deuterium neutral beams, used to heat magnetically confined fusion plasmas. Deuterium beams, of variable energies, pulse lengths, and powers up to 47 keV, 100 msec, 1.6 MW, were Rutherford backscattered at 135/sup 0/ from TiC inner neutral beam armor of the PDX, and detected using an electrostatic analyzer with microchannel plates. Complete energy scans were made every 20 msec and data were obtained simultaneously from five different positions across the beam profile. The neutral particle fractions were measured to be D/sup 0/(E):D/sup 0/(E/2):D/sup 0/(E/3)=53:32:15. The corresponding neutral power fractions were P/sup 0/(E):P/sup 0/(E/2):P/sup 0/(E/3)=72:21:7, and the associated ionic fractions at the output of the ion source were D/sub 1//sup +/(E):D/sub 2//sup +/(E):D/sub 3//sup +/(E)=74:20:6. The measured neutral particle fractions were relatively constant over more than 70% of the beam power distribution. A decrease in the yield of the full energy component in the outer regions of the beam was observed. Other possible experimental configurations and geometries are discussed.

  19. 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.

  20. 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.

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

    DOE PAGESBeta

    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,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

  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. 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.

  4. Negative ion based neutral beam injector for JT-60U

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Araki, M.; Hanada, M.; Inoue, T.; Kunieda, S.; Kuriyama, M.; Matsuoka, M.; Mizuno, M.; Ohara, Y.; Tanaka, M.; Watanabe, K.

    1992-10-01

    A 500 keV, 10 MW neutral beam injector is to be constructed in JT-60 Upgrade for the experiments of current drive and heating of heat density core plasmas. This is the first neutral beam injector in the world using negative ions as the primary ions. In the design, D- ion beams of 44 A, 500 keV are produced by two ion sources (22 A/each ion source) and neutralized in a long gas neutralizer. The total system efficiency is about 40%. The ion source is a cesium-seeded multicusp volume source having a three stage electrostatic accelerator. To reduce the stripping loss of D- ions in the accelerator, the ion source should be operated at a low pressure of 0.3 Pa with a current density of 13 mA/cm2. The first test of the full-size negative ion source is scheduled from middle of 1993.

  5. 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.

  6. 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.

  7. [Simulation of an instrumental head for 6 MeV electron beam therapy].

    PubMed

    Albini, E; Belletti, S; Corrado, F; Galelli, M; Mascaro, L

    1990-10-01

    Simulation of a therapy head for 6 MeV electron beams. We present the results of a simulation, performed using a Monte Carlo method, of depth dose curves in water for electron beams of initial kinetic energy of 6.4 MeV, generated by a radiotherapy microtron MM22 Scanditronix. The Fortran code in EGS4: comparison is made between simulated curves, obtained using various approximation criteria, and the experimental one. PMID:2251422

  8. 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.

  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. 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.

  11. 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

  12. 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.

  13. Instrumentation system for long-pulse MFTF neutral beams

    SciTech Connect

    Risch, D.M.

    1981-09-30

    The instrumentation system for long pulse neutral beams for MFTFS consists of monitoring and protective circuitry. Global synchronization of high speed monitoring data across twenty-four neutral beams is achieved via an experiment wide fiber optic timing system. Fiber optics are also used as a means of isolating signals at elevated voltages. An excess current monitor, interrupt monitor, sparkdown detector, spot detector and gradient grid ratio detector form the primary protection for the neutral beam source. A unique hierarchical interlocking scheme allows other protective devices to be factored into the shutdown circuitry of the power supply so that the initiating cause of a shutdown can be isolated and even allows some non-critical devices to be safely ignored for a period of time.

  14. Hyperthermal neutral beam sources for material processing (invited)

    SciTech Connect

    Yoo, S. J.; Kim, D. C.; Joung, M.; Kim, J. S.; Lee, B. J.; Oh, K. S.; Kim, K. U.; Kim, Y. H.; Kim, Y. W.; Choi, S. W.; Son, H. J.; Park, Y. C.; Jang, J.-N.; Hong, M. P.

    2008-02-15

    Hyperthermal neutral beams have a great potential for material processes, especially for etching and thin film deposition for semiconductor and display fabrication as well as deposition for various thin film applications. Plasma-induced damage during plasma etching is a serious problem for manufacturing deep submicron semiconductor devices and is expected to be a problem for future nanoscale devices. Thermal and plasma-induced damage is also problematic for thin film depositions such as transparent conductive oxide films on organic light emitting diodes or flexible displays due to high temperature processes in plasma environments. These problems can be overcome by damage-free and low-temperature processes with hyperthermal neutral beams. We will present the status of the hyperthermal neutral beam development and the applications, especially, in semiconductor and display fabrication and introduce potential applications of thin film growing for optoelectronic devices such as light emitting diodes.

  15. Ferroelectric Plasma Source for Heavy Ion Beam ChargeNeutralization

    SciTech Connect

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

    2005-10-01

    Plasmas are employed as a source of unbound electrons for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length {approx} 0.1-1 m would be suitable. To produce one-meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being developed. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. 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) will be covered with ceramic, and high voltage ({approx} 1-5 kV) applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long has produced plasma densities of 5 x 10{sup 11} cm{sup -3}. The source was integrated into the previous Neutralized Transport Experiment (NTX), and successfully charge neutralized the K{sup +} ion beam. Presently, the one-meter source is being fabricated. The source is being characterized and will be integrated into NDCX for charge neutralization experiments.

  16. Equilibrium and Stability Measurements via Neutral Beam Spectroscopy

    NASA Astrophysics Data System (ADS)

    Reinecke, E. A.; Fonck, R. J.; Lewicki, B. T.; Olig, A. D.; Thorson, T. A.

    2000-10-01

    An optical neutral beam spectroscopy system is being designed to provide plasma density, local temperature, internal structure of large-scale MHD instabilities, and magnetic field structure for the PEGASUS Toroidal Experiment. Time resolved, spatially localized measurements of the plasma density are determined by the intensity gradient of the beam fluorescence. Ratios of line intensities of a helium beam provide the electron temperature profile. Spectrally resolved measurements of the charge-exchange recombination emission of impurities determine the local ion temperature. Plasma stability is studied with localized MHD measurements via the beam emission spectroscopy (BES) technique. Motional Stark broadening of deuterium beam emission provide the magnitude (mod-B) and direction of the total field by analyzing the amplitude and phase delay of an oscillating spectral linewidth driven by a rotating polarizer. Present efforts are focused on refurbishing the beam hardware (25 kV, 4 A) and exploring the feasibility of a compact pencil beam.

  17. 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.

  18. 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.

  19. Measurement of neutral beam profiles at DIII-D

    SciTech Connect

    Chiu, H.

    1998-06-01

    The neutral beam systems of DIII-D, a National Fusion Facility at General Atomics, are used both for heating the plasma, and as tools for plasma diagnostics. The spatial distribution (profile) and energy of the beam is used in the absolute calibration of both the Charge Exchange Recombination (CER) and Motional Stark Effect (MSE) diagnostics. In the past, the beam spatial profile used in these calibrations was derived from beam divergence calculations and IR camera observations on the tokamak centerpost target tiles. Two experimental methods are now available to better determine the beam profile. In one method, the Doppler shifted D{sub {alpha}} light from the energetic neutrals are measured, and the full-width at half-maximum (FWHM) of the beam can be inferred from the measured divergence of the D{sub {alpha}} light intensity. The other method for determining the beam profile uses the temperature gradients measured by the thermocouples mounted on the calorimeter. A new iterative fitting routine for the measured thermocouple data has been developed to fit theoretical models on the dispersion of the beam. The results of both methods are compared, and used to provide a new experimental verification of the beam profile.

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

    PubMed

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

    2012-07-01

    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 (∼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. PMID:22852685

  2. 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.

  3. 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.

  4. 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.

  5. Surface modification using MeV ion beams

    NASA Technical Reports Server (NTRS)

    Tombrello, T. A.

    1983-01-01

    Electronic excitation induced by MeV/amu ion beams in a variety of materials has been employed successfully for a number of applications. The examples that will be presented are: modification of the surface reflectivities of optical materials; sputter-erosion of dielectrics; and enhancement of the adhesion of thin film coatings. All of these effects arise from the loss of energy by the ion beam to electrons in the target material; the mechanisms involved are at best qualitatively understood. This paper will stress not only the exploitation of such high energy bombardment techniques but will also briefly review attempts to expose the underlying causes.

  6. 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.

  7. H sup minus beam characterization using laser-induced neutralization

    SciTech Connect

    Yuan, V.W.; Garcia, R.; Johnson, K.F.; Saadatmand, K.; Sander, O.R.; Sandoval, D.; Shinas, M.

    1991-01-01

    The Laser-induced neutralization techniques, LINDA, is important as a noninterceptive diagnostic for quantitatively measuring beam emittance values. It is also valuable for its capability to characterize, both quantitatively and qualitatively, the performance and match of linac components. In this paper we present LINDA experimental results that show how the output beam of a radio-frequency quadrupole (RFQ) and drift-tube linac (DTL) combination changes with the variation of RFQ-DTL relative phase and of DTL cavity power. We also present results showing the effect of a longitudinal buncher on beam emissions. 2 refs., 4 figs.

  8. 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.

  9. 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.

  10. Output Beam Characteristics of 150 MeV Microtron

    NASA Astrophysics Data System (ADS)

    Hori, T.; Tsutsui, H.; Amano, D.; Washio, M.; Yang, J.; Tani, K.

    1997-05-01

    High quality X-ray beam of the pico- to femtosecond pulse width is an indispensable tool for the investigation of various phenomena in the same time scale. Thomson Scattering between electrons and laser beams is considered to be the most promising ("Femtosecond X-ray Pulse Generation Using a Low Emittance Electron Beam and a High Power Laser" M. WASHIO, et al. 7th China-Japan Bilateral Symp. on Radiation Chem., Oct. 28, 1996, Chengdu, China.) to generate that kind of X-ray. For such the purpose, it is inevitable to procure a high quality electron beam of very short and low emittance pulse. We believe that racetrack microtron (RTM) is the best candidate to realize the above interaction because of its compactness which is essential in this experiment. Of course even for the system including RTM, it is obvious that we should adopt the new technology of RF gun with photo cathode in its injection system. We have started as a preliminary work investigating the behavior of conventional RTM which has an 80 keV thermionic gun. Here presented are the experimental results of emittance and enegy spread measurements together with the simulation results of bunch shortening effect of RTM.

  11. Plasma neutralization models for intense ion beam transport in plasma

    SciTech Connect

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.; O'Rourke, Sean; Lee, Edward P.

    2003-05-01

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed based on the assumption of long charge bunches (l{sub b} >> r{sub b}). Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The analytical predictions for the degree of ion beam charge and current neutralization also agree well with the results of the numerical simulations. The model predicts very good charge neutralization (>99%) during quasi-steady-state propagation, provided the beam pulse duration {tau}{sub b} is much longer than the electron plasma period 2{pi}/{omega}{sub p}, where {omega}{sub p} = (4{pi}e{sup 2}n{sub p}/m){sup 1/2} is the electron plasma frequency, and n{sub p} is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. The analytical formulas derived in this paper can provide an important benchmark for numerical codes, and provide scaling relations for different beam and plasma parameters.

  12. 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.

  13. 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.

  14. Emittance Analysis of the DIII-D Neutral Beam Source

    NASA Astrophysics Data System (ADS)

    Lopez, N. A.; Crowley, B.

    2014-10-01

    In a high powered neutral beam system ions are extracted from a low temperature plasma, through apertures in the arc chamber, by application of a potential to an external electrode. It has been determined that to increase the beam energy of the DIII-D neutral beam system beyond 95 keV the accelerator must be reconfigured to avoid excessive electrical breakdown in the grid gaps. Deciding exactly what modifications are to be made requires modeling and experimental effort. A basic problem is to find a geometry with which the extracted beam is intense, low divergence, free of aberrations, and does not strike the focusing electrodes. We present the results of modeling proposed reconfigurations to the accelerator geometry and source conditions. The quality of the beam produced from the various accelerator configurations is quantified through metrics such as the beam emittance and the average divergence per beamlet. By comparing the beam quality and power delivered for each proposed reconfiguration an optimal design is selected and recommended. Work supported in part by the National Undergraduate Fellowship Program in Plasma Physics and Fusion Energy Sciences and the US DOE under DE-FG02-94ER54235, DE-FC02-04ER54698.

  15. 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. PMID:26628137

  16. 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.

  17. 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.

  18. 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.

  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. 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.

  1. Fabrication of microfluidic devices using MeV ion beam Programmable Proximity Aperture Lithography (PPAL)

    NASA Astrophysics Data System (ADS)

    Gorelick, S.; Puttaraksa, N.; Sajavaara, T.; Laitinen, M.; Singkarat, S.; Whitlow, H. J.

    2008-05-01

    MeV ion beam lithography is a direct writing technique capable of producing microfluidic patterns and lab-on-chip devices with straight walls in thick resist films. In this technique a small beam spot of MeV ions is scanned over the resist surface to generate a latent image of the pattern. The microstructures in resist polymer can be then revealed using a chemical developer that removes exposed resist, while leaving unexposed resist unaffected. In our system the size of the rectangular beam spot is programmably defined by two L-shaped tantalum blades with well-polished edges. This allows rapid exposure of entire rectangular pattern elements up to 500 × 500 μm in one step. By combining different dimensions of the defining aperture with the sample movements relative to the beam spot, entire fluidic patterns with large reservoirs and narrow flow channels can be written over large areas in short time. Fluidic patterns were written in PMMA using 56 MeV 14N3+ and a 3 MeV 4He2+ beams from K130 cyclotron and a 1.7 MV Pelletron accelerators, respectively, at the University of Jyväskylä Accelerator Laboratory. The patterns were characterized using SEM, and the factors affecting patterns quality are discussed.

  2. 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.

  3. Development of mass spectrometry by high energy focused heavy ion beam: MeV SIMS with 8 MeV Cl7+ beam

    NASA Astrophysics Data System (ADS)

    Jeromel, Luka; Siketić, Zdravko; Ogrinc Potočnik, Nina; Vavpetič, Primož; Rupnik, Zdravko; Bučar, Klemen; Pelicon, Primož

    2014-08-01

    Particle induced X-ray emission (PIXE) at microprobe of Jožef Stefan Institute is used to measure two-dimensional quantitative elemental maps of biological tissue. To improve chemical and biological understanding of the processes in vivo, supplementary information about chemical bonding and/or molecular distributions could be obtained by heavy-ion induced molecular desorption and a corresponding mass spectroscopy with Time-Of-Flight (TOF) mass spectrometer. As the method combines the use of heavy focused ions in MeV energy range and TOF Secondary Ion Mass Spectrometry, it is denoted as MeV SIMS. At Jožef Stefan Institute, we constructed a linear TOF spectrometer and mount it to our multipurpose nuclear microprobe. A beam of 8 MeV 35Cl7+ could be focused to a diameter of better than 3 μm × 3 μm and pulsed by electrostatic deflection at the high-energy side of accelerator. TOF mass spectrometer incorporates an 1 m long drift tube and a double stack microchannel plate (MCP) as a stop detector positioned at the end of the drift path. Secondary ions are focused at MCP using electrostatic cylindrical einzel lens. Time of flight spectra are currently acquired with a single-hit time-to-digital converter. Pulsed ion beam produces a shower of secondary ions that are ejected from positively biased target and accelerated towards MCP. We start our time measurement simultaneously with the start of the beam pulse. Signal of the first ion hitting MCP is used to stop the time measurement. Standard pulses proportional to the time of flight are produced with time to analog converter (TAC) and fed into analog-to-digital converter to obtain a time histogram. To enable efficient detection of desorbed fragments with higher molecular masses, which are of particular interest, we recently implemented a state-of art Field Programmable Gate Array (FPGA)-based multi-hit TOF acquisition. To test the system we used focused 8 MeV 35Cl7+ ion beam with pulse length of 180 ns. Mass resolution

  4. 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.

  5. 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.

  6. 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.

  7. Neutral beam heating of detached plasmas in TFTR

    SciTech Connect

    Bush, C.E.; Strachan, J.D.; Schivell, J.; Mansfield, D.K.; Taylor, G.; Grek, B.; Budny, R.; McNeill, D.H.; Bell, M.G.; Boody, F.P.

    1989-05-01

    Detached plasmas on TFTR have been heated with neutral beam auxiliary power for the first time. At beam powers above 2 MW the detached plasmas in TFTR expand and reattach to the limiters. Deuterium and/or impurity gas puffing can be used to maintain plasmas in the detached state at powers of over 5 MW. Transient events were observed in a number of these plasmas, including a confinement-related delay in evolution of the edge emissivity and some phenomena which appear similar to those seen in the H-mode. 16 refs., 5 figs.

  8. Conceptual design for the ZEPHYR neutral-beam injection system

    SciTech Connect

    Cooper, W.S.; Elischer, V.P.; Goldberg, D.A.; Hopkins, D.B.; Jacobson, V.L.; Lou, K.H.; Tanabe, J.T.

    1981-03-01

    In June 1980, the Lawrence Berkeley Laboratory began a conceptual design study for a neutral beam injection system for the ZEPHYR ignition tokamak proposed by the Max-Planck-Institut fur Plasmaphysik in Garching, Germany. The ZEPHYR project was cancelled, and the LBL design effort concluded prematurely in January 1981. This report describes the conceptual design as it existed at that time, and gives brief consideration to a schedule, but does not deal with costs.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Design of a compact spectrometer for high-flux MeV gamma-ray beams

    SciTech Connect

    Corvan, D. J. Sarri, G.; Zepf, M.

    2014-06-15

    A novel design for a compact gamma-ray spectrometer is presented. The proposed system allows for spectroscopy of high-flux multi-MeV gamma-ray beams with MeV energy resolution in a compact design. In its basic configuration, the spectrometer exploits conversion of gamma-rays into electrons via Compton scattering in a low-Z material. The scattered electron population is then spectrally resolved using a magnetic spectrometer. The detector is shown to be effective for gamma-ray energies between 3 and 20 MeV. The main properties of the spectrometer are confirmed by Monte Carlo simulations.

  16. 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%.

  17. 1000 MeV Proton beam therapy facility at Petersburg Nuclear Physics Institute Synchrocyclotron

    NASA Astrophysics Data System (ADS)

    Abrosimov, N. K.; Gavrikov, Yu A.; Ivanov, E. M.; Karlin, D. L.; Khanzadeev, A. V.; Yalynych, N. N.; Riabov, G. A.; Seliverstov, D. M.; Vinogradov, V. M.

    2006-05-01

    Since 1975 proton beam of PNPI synchrocyclotron with fixed energy of 1000 MeV is used for the stereotaxic proton therapy of different head brain diseases. 1300 patients have been treated during this time. The advantage of high energy beam (1000 MeV) is low scattering of protons in the irradiated tissue. This factor allows to form the dose field with high edge gradients (20%/mm) that is especially important for the irradiation of the intra-cranium targets placed in immediate proximity to the life critical parts of the brain. Fixation of the 6 0mm diameter proton beam at the isodose centre with accuracy of ±1.0 mm, two-dimensional rotation technique of the irradiation provide a very high ratio of the dose in the irradiation zone to the dose at the object's surface equal to 200:1. The absorbed doses are: 120-150 Gy for normal hypophysis, 100-120 Gy for pituitary adenomas and 40-70 Gy for arterio-venous malformation at the rate of absorbed dose up to 50 Gy/min. In the paper the dynamics and the efficiency of 1000 MeV proton therapy treatment of the brain deceases are given. At present time the feasibility study is in progress with the goal to create a proton therapy on Bragg peak by means of the moderation of 1000 MeV proton beam in the absorber down to 200 MeV, energy required for radiotherapy of deep seated tumors.

  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. 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. PMID:22380259

  20. 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.

  1. 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.

  2. 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. PMID:24953537

  3. 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

  4. Cryosorption Pumps for a Neutral Beam Injector Test Facility

    SciTech Connect

    Dremel, M.; Mack, A.; Day, C.; Jensen, H.

    2006-04-27

    We present the experiences of the manufacturing and the operating of a system of two identical cryosorption pumps used in a neutral beam injector test facility for fusion reactors. Calculated and measured heat loads of the cryogenic liquid helium and liquid nitrogen circuits of the cryosorption pumps are discussed. The design calculations concerning the thermo-hydraulics of the helium circuit are compared with experiences from the operation of the cryosorption pumps. Both cryopumps are integrated in a test facility of a neutral beam injector that will be used to heat the plasma of a nuclear fusion reactor with a beam of deuterium or hydrogen molecules. The huge gas throughput into the vessel of the test facility results in challenging needs on the cryopumping system.The developed cryosorption pumps are foreseen to pump a hydrogen throughput of 20 - 30 mbar{center_dot}l/s. To establish a mean pressure of several 10-5 mbar in the test vessel a pumping speed of about 350 m3/s per pump is needed. The pressure conditions must be maintained over several hours pumping without regeneration of the cryopanels, which necessitates a very high pumping capacity. A possibility to fulfill these requirements is the use of charcoal coated cryopanels to pump the gasloads by adsorption. For the cooling of the cryopanels, liquid helium at saturation pressure is used and therefore a two-phase forced flow in the cryopump system must be controlled.

  5. 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.

  6. 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.

  7. Neutral beam injectors for the Big Dee vessel

    SciTech Connect

    Doll, D.W.; Bailey, E.; Colleraine, A.; Fasolo, J.; Hager, R.; Peuron, A.; Rawls, J.; Sanchez, H.

    1983-12-01

    The four neutral beam injectors built for Doublet III will be modified to reoptimize beam transmission into the Big Dee vessel. All beamline components will be remounted 90/sup 0/ to their original position in the cylindrical vacuum vessel. This will permit optimum alignment with the available port opening. While these modifications are being incorporated into the disassembled injectors, it is planned that improvements and upgrading features will be added at the least possible cost. The calorimeter will be replaced by two independently driven calorimeters, thus decoupling the operation of the two ion sources. The beam path is being opened up to accommodate a long pulse (cw) source and all beam absorbing surfaces are being increased in size to withstand up to 5 s of operation with heat fluxes up to 700 W/cm/sup 2/. By opening up the apertures along the beam trajectory, an increase in power transmission into the plasma of 33% is realized compared with the present Doublet III performance.

  8. SIPHORE: Conceptual Study of a High Efficiency Neutral Beam Injector Based on Photo-detachment for Future Fusion Reactors

    SciTech Connect

    Simonin, A.; Christin, L.; Esch, H. de; Garibaldi, P.; Grand, C.; Villecroze, F.; Blondel, C.; Delsart, C.; Drag, C.; Vandevraye, M.; Brillet, A.; Chaibi, W.

    2011-09-26

    An innovative high efficiency neutral beam injector concept for future fusion reactors is under investigation (simulation and R and D) between several laboratories in France, the goal being to perform a feasibility study for the neutralization of intense high energy (1 MeV) negative ion (NI) beams by photo-detachment.The objective of the proposed project is to put together the expertise of three leading groups in negative ion quantum physics, high power stabilized lasers and neutral beam injectors to perform studies of a new injector concept called SIPHORE (SIngle gap PHOto-neutralizer energy REcovery injector), based on the photo-detachment of negative ions and energy recovery of unneutralised ions; the main feature of SIPHORE being the relevance for the future Fusion reactors (DEMO), where high injector efficiency (up to 70-80%), technological simplicity and cost reduction are key issues to be addressed.The paper presents the on-going developments and simulations around this project, such as, a new concept of ion source which would fit with this injector topology and which could solve the remaining uniformity issue of the large size ion source, and, finally, the presentation of the R and D program in the laboratories (LAC, ARTEMIS) around the photo-neutralization for Siphore.

  9. 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.

  10. 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. PMID:20192410

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

    SciTech Connect

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

    2010-02-15

    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.

  12. 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.

  13. Dose distribution outside the target volume for 170-MeV proton beam.

    PubMed

    Pachnerová Brabcová, K; Ambrožová, I; Kubančák, J; Puchalska, M; Vondráček, V; Molokanov, A G; Sihver, L; Davídková, M

    2014-10-01

    Dose delivered outside the proton field during radiotherapy can potentially lead to secondary cancer development. Measurements with a 170-MeV proton beam were performed with passive detectors (track etched detectors and thermoluminescence dosemeters) in three different depths along the Bragg curve. The measurement showed an uneven decrease of the dose outside of the beam field with local enhancements. The major contribution to the delivered dose is due to high-energy protons with linear energy transfer (LET) up to 10 keV µm(-1). However, both measurement and preliminary Monte Carlo calculation also confirmed the presence of particles with higher LET. PMID:24759915

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Neutral Atom Lithography Using a Bright Metastable Helium Beam

    NASA Astrophysics Data System (ADS)

    Shean, Claire; Reeves, Jason; Metcalf, Harold

    2008-05-01

    We have performed neutral atom lithography using a bright beam of metastable Helium (He*) that is collimated with the bichromatic force followed by two Doppler molasses velocity compression stages. We have previously demonstrated this lithography method using a metal grid to project its image on a self assembled monolayer (SAM) of nonanethiol. The open areas of the grid allow incident He* to damage the SAM molecules by depositing their 20 eV of internal energy on the surface. The undisturbed SAM regions then protect a gold coated Silicon wafer from a wet chemical etch. Samples created with this method have an edge resolution of 63 nm that was observed using an atomic force microscope. We have now achieved focusing of the He* beam into lines by the dipole force that the atoms experience while traversing a standing wave of λ = 1083 nm light tuned 500 MHz above the 2^3S1-->2^3P2 transition. The lines are separated by λ/2 and their length is comparable to the laser beam waist. Because bichromatic collimation makes such an intense He* beam, our exposure time can be as short as 10 minutes.

  20. Neutral Atom Lithography Using a Bright Metastable Helium Beam

    NASA Astrophysics Data System (ADS)

    Allred, Claire; Reeves, Jason; Corder, Chris; Metcalf, Harold

    2009-05-01

    We have performed neutral atom lithography using a bright beam of metastable 2^3S1 Helium (He*) that is collimated with the bichromatic force, followed by three optical molasses velocity compression stages. Because bichromatic collimation makes such an intense He* beam, our exposure time is measured in minutes instead of hours. We have exploited the focusing and channeling of the He* beam into lines by the dipole force the atoms experience while traversing a standing wave of λ = 1083 nm light tuned 500 MHz below the 2^3S1-> 2^3P2 transition. Focused He* atoms damage the molecules of a self assembled monolayer (SAM) of nonanethiol by depositing their 20 eV of internal energy on its surface. The undisturbed SAM then protects a 200 å,ayer of gold that has been evaporated onto a prepared Silicon wafer from a wet chemical etch. Samples created with this method have an edge resolution of 63 nm that was observed using an atomic force microscope. The lines are separated by λ/2 and cover the entire exposed length of the substrate, about 3 mm. They are about 3 mm long, corresponding to about twice the beam waist of the laser standing wave. Thus there are ˜6 x10^3 lines of length ˜1500 λ. These results agree with our numerical simulations of the experiment.

  1. 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.

  2. Vacuum system of the 3MeV industrial electron beam accelerator

    NASA Astrophysics Data System (ADS)

    Jayaprakash, D.; Mishra, R. L.; Ghodke, S. R.; kumar, M.; kumar, M.; Nanu, K.; Mittal, K. C., Dr

    2008-05-01

    One DC Accelerator, for electron beam of 3 MeV energy and 10 mA beam current, to derive 30 KW beam power for Industrial applications is nearing completion at Electron Beam Centre, Kharghar, Navi Mumbai. Beam-line of the accelerator is six meters long, consists of electron gun at top, followed by the accelerating column and finally the scan horn. Electron gun and the accelerating column is exposed to SF6 gas at six atmospheres. Area exposed to the vacuum is 65,000 sq: cm, and includes a volume of 200 litres. Vacuum of the order of 1×10-7mbar is desired. To ensure a good vacuum gradient, distributive pumping is implemented. Electron beam is scanned to a size of 5cm × 120cm, to get a useful beam coverage, for industrial radiation applications. The beam is extracted through a window of Titanium foil of 50μm thickness. A safety interlock, to protect the electron gun, accelerating column and sputter ion pumps, in case of a foil rupture, is incorporated. Foil change can be done without disturbing the vacuum in the other zones. System will be integrated to a master control system to take care of the various safety aspects, and to make it operator friendly.

  3. Neutral Beam Current Drive in Spheromak plasma and plasma stability

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

    A key question for the Sustained Spheromak Physics Experiment (SSPX) is understanding how spheromaks can be sustained by other current drive tools such as neutral beam current drive. Another question is whether the present relationship between current and maximum spheromak magnetic field (plasma beta) is related to Alcator-like ohmic confinement limit or is a stability limit. Using the code CORSICA, the fraction of neutral beam current drive that can be achieved has been calculated for different injection angles with a fixed equilibrium. It is seen that relaxing the equilibrium with this drive simply drives the core safety factor to low values. Other equilibria where the NBI may give aligned current drive are being explored. Free-boundary equilibria calculations are underway to see what hyper-resistivity model gives the observed sustained SSPX performance and include that in the NBI calculations. Work performed under the auspices of the US DOE by University of California Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  4. 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.

  5. 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.

  6. 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.

  7. Performance of the KTeV high-energy neutral kaon beam at Fermilab

    SciTech Connect

    Bocean, V.

    1998-06-01

    The performance of the primary and secondary beams for the KTeV experiments E832 and E799-II is reviewed. The beam was commissioned in the summer of 1996 and initially operated for approximately one year. The report includes results on the primary beam, target station including primary beam dump and muon sweeping system, neutral beam collimation system, and alignment.

  8. Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

    SciTech Connect

    Kaganovich, I.D.; Davidson, R.C.; Dorf, M.; Startsev, E.A.; Barnard, J.J.; Friedman, A.; Lee, E.P.; Lidia, S.M.; Logan, B.G.; Roy, P.K.; Seidl, P.A.; Welch, D.R.; Sefkow, A.B.

    2009-04-28

    Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.

  9. Beam-dump/diagnostics box for a 10-kA 50-MeV, 50-ns electron beam

    SciTech Connect

    White, J.M.; Fessenden, T.J.; Fontaine, R.A.; Harvey, A.R.; Paul, A.C.

    1983-03-09

    We have developed a dump for the ATA beam that consists of a series of carbon plates whose collective thickness totals approximately 1.5 ranges at 50 MeV. The energy dissipated in the plates is radiated to a water-cooled wall. The dump is designed to dissipate up to 175 kW of average power. A small hole along the axis of the plates forms a beamlet that passes through an energy analyzer. The analyzer consists of a 60/sup 0/ bending magnet and two high-sensitivity beam-current/position monitors. The ratio of the beamlet current to full current is used to estimate the beam emittance.

  10. 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.

  11. 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.

  12. MeV ion beam interaction with polymer films containing cross-linking agents

    SciTech Connect

    Evelyn, A. L.

    1999-06-10

    Polymer films containing cross linking enhancers were irradiated with MeV alpha particles to determine the effects of MeV ion beam interaction on these materials. The contributed effects from the electronic and nuclear stopping powers were separated by irradiating stacked thin films of polyvinyl chloride (PVC), polystyrene (PS) and polyethersulfone (PES). This layered system allowed most of the effects of the electronic energy deposited to be experienced by the first layers and the last layers to receive most of the effects of the nuclear stopping power. RGA, Raman microprobe analysis, RBS and FTIR measured changes in the chemical structures of the irradiated films. The characterization resolved the effects of the stopping powers on the PVC, PS and PES and the results were compared with those from previously studied polymers that did not contain any cross linking agents.

  13. 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.

  14. 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.

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

    SciTech Connect

    Grierson, B. A. Grisham, L.; Burrell, K. H.; Crowley, B.; Scoville, J. T.

    2014-10-15

    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 [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] 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. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Confinement studies of neutral beam heated discharges in TFTR

    SciTech Connect

    Murakami, M.; Arunasalam, V.; Bell, J.D.; Stauffer, F.; Bell, M.G.; Bitte, M.; Blanchard, W.R.; Boody, F.; Britz, N.

    1985-11-01

    The TFTR tokamak has reached its original machine design specifications (I/sub p/ = 2.5 MA and B/sub T/ = 5.2T). Recently, the D/sup 0/ neutral beam heating power has been increased to 6.3 MW. By operating at low plasma current (I/sub p/ approx. = 0.8 MA) and low density anti n/sub e/ approx. = 1 x 10/sup 19/m/sup -3/), high ion temperatures (9 +- keV) and rotation speeds (7 x 10/sup 5/ m/s) have been achieved during injection. At the opposite extreme, pellet injection into high current plasmas has been used to increase the line-average density to 8 x 10/sup 19/m/sup -3/ and the central density to 1.6 x 10/sup 20/m/sup -3// This wide range of operating conditions has enabled us to conduct scaling studies of the global energy confinement time in both ohmically and beam heated discharges as well as more detailed transport studies of the profile dependence. In ohmic discharges, the energy confinement time is observed to scale linearly with density only up to anti n/sub e/ approx. 4.5 x 10/sup 19/m/sup -3/ and then to increase more gradually, achieving a maximum value of approx. 0.45 s. In beam heated discharges, the energy confinement time is observed to decrease with beam power and to increase with plasma current. With P/sub b/ = 5.6 MW, anti n/sub e/ = 4.7 x 10/sup 19/m/sup -3/, I/sub p/ = 2.2 MA and B/sub T = 4.7T, the gross energy confinement time is 0.22 s and T/sub i/(0) = 4.8 keV. Despite shallow penetration of D/sup 0/ beams (at the beam energy less than or equal to 80 keV with low species yield), tau/sub E/(a) values are as large as those for H/sup 0/ injection, but central confinement times are substantially greater. This is a consequence of the insensitivity of the temperature and safety factor profile shapes to the heating profile. The radial variation of tau/sub E/ is even more pronounced with D/sup 0/ injection into high density pellet-injected plasmas. 25 refs.

  20. Sawtooth stability in neutral beam heated plasmas in TEXTOR

    NASA Astrophysics Data System (ADS)

    Chapman, I. T.; Pinches, S. D.; Koslowski, H. R.; Liang, Y.; Krämer-Flecken, A.; TEXTOR Team; de Bock, M.

    2008-03-01

    The experimental sawtooth behaviour in neutral beam injection (NBI) heated plasmas in TEXTOR is described. It is found that the sawtooth period is minimized with a low NBI power oriented in the same direction as the plasma current. As the beam power is increased in the opposite direction to the plasma current, the sawtooth period increases to a maximum before it begins to shorten once more. Results from both magnetohydrodynamic stability modelling including toroidal flows and modelling of the kinetic effects of the fast ions resulting from NBI heating are also presented. This model combining the gyroscopic and kinetic effects upon the stability of the n = 1 internal kink mode—thought to be associated with sawtooth oscillations—qualitatively recovers the sawtooth behaviour exhibited in the experiment. It is proposed that the sawtooth period is minimized in the co-NBI direction at the point at which the stabilization of the kink mode due to rotation is weakest. This occurs when the plasma rotation induced by the NBI balances the intrinsic rotation of the plasma. The sawtooth behaviour in the counter-NBI regime is attributed to a subtle balance of the competing stabilization from the toroidal rotation and destabilization from the presence of energetic ions.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Benchmark of 3D halo neutral simulation in TRANSP and FIDASIM and application to projected neutral-beam-heated NSTX-U plasmas

    NASA Astrophysics Data System (ADS)

    Liu, D.; Medley, S. S.; Gorelenkova, M. V.; Heidbrink, W. W.; Stagner, L.

    2014-10-01

    A cloud of halo neutrals is created in the vicinity of beam footprint during the neutral beam injection and the halo neutral density can be comparable with beam neutral density. Proper modeling of halo neutrals is critical to correctly interpret neutral particle analyzers (NPA) and fast ion D-alpha (FIDA) signals since these signals strongly depend on local beam and halo neutral density. A 3D halo neutral model has been recently developed and implemented inside TRANSP code. The 3D halo neutral code uses a ``beam-in-a-box'' model that encompasses both injected beam neutrals and resulting halo neutrals. Upon deposition by charge exchange, a subset of the full, one-half and one-third beam energy components produce thermal halo neutrals that are tracked through successive halo neutral generations until an ionization event occurs or a descendant halo exits the box. A benchmark between 3D halo neural model in TRANSP and in FIDA/NPA synthetic diagnostic code FIDASIM is carried out. Detailed comparison of halo neutral density profiles from two codes will be shown. The NPA and FIDA simulations with and without 3D halos are applied to projections of plasma performance for the National Spherical Tours eXperiment-Upgrade (NSTX-U) and the effects of halo neutral density on NPA and FIDA signal amplitude and profile will be presented. Work supported by US DOE.

  7. Attainment of a high-quality electron beam for Fermilab's 4.3 MeV cooler

    SciTech Connect

    Shemyakin, A.; Burov, Alexey V.; Carlson, K.; Hu, M.; Kazakevich, G.; Kramper, B.; Kroc, T.; Leibfritz, J.; Nagaitsev, S.; Prost, L.; Pruss, S.; Saewert, G.; Schmidt, C.W.; Seletskiy, S.; Sutherland, M.; Tupikov, V.; Warner, A.; /Fermilab /Novosibirsk, IYF /Rochester U.

    2005-11-01

    The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler's electron beam and details of operation.

  8. Attainment of a High-Quality Electron Beam for Fermilab's 4.3 MeV Cooler

    SciTech Connect

    Shemyakin, A.; Burov, A.; Carlson, K.; Hu, M.; Kramper, B.; Kroc, T.; Leibfritz, J.; Nagaitsev, S.; Prost, L.; Pruss, S.; Saewert, G.; Schmidt, C. W.; Sutherland, M.; Tupikov, V.; Warner, A.; Kazakevich, G.; Seletskiy, S.

    2006-03-20

    The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler's electron beam and details of operation.

  9. 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.

  10. Powerloads on the front end components and the duct of the heating and diagnostic neutral beam lines at ITER

    NASA Astrophysics Data System (ADS)

    Singh, M. J.; Boilson, D.; Hemsworth, R. S.; Geli, F.; Graceffa, J.; Urbani, M.; Dlougach, E.; Krylov, A.; Schunke, B.; Chareyre, J.

    2015-04-01

    The heating and current drive beam lines (HNB) at ITER are expected to deliver ˜16.7 MW power per beam line for H beams at 870 keV and D beams at 1 MeV during the H-He and the DD/DT phases of ITER operation respectively. On the other hand the diagnostic neutral beam (DNB) line shall deliver ˜2 MW power for H beams at 100 keV during both the phases. The path lengths over which the beams from the HNB and DNB beam lines need to be transported are 25.6 m and 20.7 m respectively. The transport of the beams over these path lengths results in beam losses, mainly by the direct interception of the beam with the beam line components and reionisation. The lost power is deposited on the surfaces of the various components of the beam line. In order to ensure the survival of these components over the operational life time of ITER, it is important to determine to the best possible extent the operational power loads and power densities on the various surfaces which are impacted by the beam in one way or the other during its transport. The main factors contributing to these are the divergence of the beamlets and the halo fraction in the beam, the beam aiming, the horizontal and vertical misalignment of the beam, and the gas profile along the beam path, which determines the re-ionisation loss, and the re-ionisation cross sections. The estimations have been made using a combination of the modified version of the Monte Carlo Gas Flow code (MCGF) and the BTR code. The MCGF is used to determine the gas profile in the beam line and takes into account the active gas feed into the ion source and neutraliser, the HNB-DNB cross over, the gas entering the beamline from the ITER machine, the additional gas atoms generated in the beam line due to impacting ions and the pumping speed of the cryopumps. The BTR code has been used to obtain the power loads and the power densities on the various surfaces of the front end components and the duct modules for different scenarios of ITER operation

  11. 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.

  12. Global energy confinement scaling for neutral-beam-heated tokamaks

    SciTech Connect

    Kaye, S.M.; Goldston, R.J.

    1984-10-01

    A total of 677 representative discharges from seven neutral-beam-heated tokamaks has been used to study the parametric scaling of global energy confinement time. Contributions to this data base were from ASDEX, DITE, D-III, ISX-B, PDX, PLT, and TFR, and were taken from results of gettered, L-mode type discharges. Assuming a power law dependence of tau/sub E/ on discharge parameters kappa, I/sub p/, B/sub t/, anti n/sub e/ P/sub tot/, a, and R/a, standard multiple linear regression techniques were used in two steps to determine the scaling. The results indicate that the discharges used in the study are well described by the scaling tau/sub E/ ..cap alpha.. kappa/sup 0.28/ B/sub T//sup -0.09/ I/sub p//sup 1.24/anti n/sub e//sup -0.26/ P/sub tot//sup -0.58/ a/sup 1.16/ (R/a)/sup 1.65/.

  13. 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.

  14. 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.

  15. 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.

  16. Effects of MHD instabilities on neutral beam current drive

    DOE PAGESBeta

    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-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

  17. Performance of Doublet III neutral beam injector cryopumping system

    SciTech Connect

    Langhorn, A.R.; Kim, J.; Tupper, M.L.; Williams, J.P.; Fasolo, J.

    1984-04-01

    The Doublet III neutral beam injector system is based on three beamlines; each beamline employs two 80 kV/80 A hydrogen ion sources. Two liquid helium (LHe) cooled cryopanel arrays were designed as an integral part of the beamline in order to provide high differential pumping of hydrogen gas along the beamline. The cryopanel arrays consist of a front (nearer to the torus) disk panel (3 m/sup 2/ each side) with liquid nitrogen (LN/sub 2/) cooled chevrons and a rear cylindrical panel of modified Santeler panels (8 m/sup 2/) which also employs LN/sub 2/ cooled surfaces shielding LHe cooled surfaces. These cryopanels are piped in series. The LHe delivery is based on a closed-loop, forced-flow scheme intended for variable panel temperatures (3.7 to 4.3 K). It uses small tubes for mechanical flexibility and thermal resiliency providing ease of economic defrosting. The cryogenic system consists of a liquefier (100 l/h), a large Dewar, a heat exchanger, and a liquid ring pump. Three beamlines are serviced simultaneously by the system. Pumping speeds measured locally at ionization gauges, were well in excess of the 1.4 x 10/sup 6/ l/s design goal.

  18. POP Experiment of Laser Stripping via a Broad Stark State Using BNL 200MeV H- Beams

    SciTech Connect

    Yamane, I.; Mimashi, T.; Nakayama, H.; Suzuki, T.; Takayama, K.; Tawada, M.; Satoh, K.; Raparia, D.; Alessi, J.; Blaskiewicz, M.; Cameron, P.; Connoly, R.; Hershcovitch, A.; Lee, Y.Y.; LoDestro, V.; Ritter, J.; Wei, J.

    2005-06-08

    Present status of the project of the POP (proof of principle) experiment of laser stripping using BNL 200MeV H- is presented. First, the principle of the laser stripping via a broad Stark state and the role of the broad Stark state are introduced. Then, the scheme of the POP experiment using 200MeV H- is given. Then, the concrete plan of experimental setup in the REF beam line of the BNL 200MeV H- Linac and present status of construction are given.

  19. 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.

  20. Comparison of radiobiological effective depths in 65-MeV modulated proton beams.

    PubMed Central

    Tang, J. T.; Inoue, T.; Inoue, T.; Yamazaki, H.; Fukushima, S.; Fournier-Bidoz, N.; Koizumi, M.; Ozeki, S.; Hatanaka, K.

    1997-01-01

    To assess the achievement of uniformity of radiobiological effectiveness at different depths in the proton spread-out Bragg peak (SOBP), Chinese hamster ovary (CHO) cells were exposed to 65-MeV modulated proton beams at the Research Center for Nuclear Physics (RCNP) of Osaka University. We selected four different irradiation positions: 2 mm depth, corresponding to the entrance, and 10, 18 and 23 mm depths, corresponding to different positions in the SOBP. Cell survival curves were generated with the in vitro colony formation method and fitted to the linear-quadratic model. With 137Cs gamma-rays as the reference irradiation, the relative biological effectiveness (RBE) values for a surviving fraction (SF) level of 0.1 are 1.05, 1.10, 1.12 and 1.19 for depths of 2, 10, 18 and 23 mm respectively. A significant difference was found between the survival curves at 10 and 23 mm (P < 0.05), but not between 18 and 10 mm or between 18 and 23 mm. There was a significant dependence of RBE on depths in modulated proton beams at the 0.1 surviving fraction level (P < 0.05). Moreover, the rise of RBEs significantly depended on increasing SF level or decreased approximately in correspondence with irradiation dose (P = 0.0001). To maintain uniformity of radiobiological effectiveness for the target volume, careful attention should be paid to the influence of depth of beam and irradiation dose. PMID:9231922

  1. High-resolution spectral analysis of light from neutral beams and ion source plasmas

    SciTech Connect

    McNeill, D H; Kim, J

    1980-05-01

    The spectral distributions of Balmer alpha emission from 7- and 22-cm-diam neutral hydrogen beams have been measured with a Fabry-Perot interferometer to obtain information on the beam energy, divergence, and species composition. Results of these measurements are compared with other data on the beam properties to evaluate high-resolution spectroscopy as a beam diagnostic technique. Measurements on ion source plasmas and on beam-produced background plasmas yield average neutral atom energies of approximately 0.3 and 2.5 eV, respectively.

  2. 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.

  3. 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. PMID:24593596

  4. 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.

  5. 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.

  6. Characterization of the proton beam at the output of the 6.7MeV LEDA RFQ.

    SciTech Connect

    Allen, C. K.; Colestock, P. L. ,; Gilpatrick, J. D.; Lysenko, W. P.; Rybarcyk, L. J.; Schneider, J. D.; Sheffield, R. L.; Smith, H. V.; Wangler, Thomas P.,; Crandall, K. R.; Chan, D.; Garnett, R. W.; Schulze, M. E.

    2001-01-01

    The present configuration of the Low-Energy Demonstration Accelerator (LEDA) consists of a 75-keV proton injector, a 6.7-MeV 350-MHz cw radio-frequency quadrupole (RFQ) with associated high-power and lowlevel rf systems, a 52-magnet periodic lattice followed by a short high-energy beam transport (HEBT) and highpower (670-kW cw) beam stop. The rms beam emittance was measured prior to the installation of the 52-magnet lattice, based on wire-scanner measurements of the beam profile at a single location in the HEBT. New measurements with additional diagnostic hardware have been performed to determine the rms transverse beam properties of the beam at the output of the 6.7-MeV LEDA RFQ. The 52-magnet periodic lattice also includes ten beam position monitors (BPMs) evenly spaced in pairs of two. The BPMs provide a measure of the bunched beam current that exhibits nulls at different locations in the lattice. Model predictions of the locations of the nulls and the strength of the bunched beam current are made to determine what information this data can provide regarding the longitudinal beam emittance.

  7. Measurement of the force on microparticles in a beam of energetic ions and neutral atoms

    SciTech Connect

    Trottenberg, Thomas; Schneider, Viktor; Kersten, Holger

    2010-10-15

    The force on microparticles in an energetic ion beam is investigated experimentally. Hollow glass microspheres are injected into the vertically upward directed beam and their trajectories are recorded with a charge-coupled device camera. The net force on the particles is determined by means of the measured vertical acceleration. The resulting beam pressures are compared with Faraday cup measurements of the ion current density and calorimetric measurements of the beam power density. Due to the neutral gas background, the beam consists, besides the ions, of energetic neutral atoms produced by charge-exchange collisions. It is found that the measured composition of the drag force by an ion and a neutral atom component agrees with a beam model that takes charge-exchange collisions into account. Special attention is paid to the momentum contribution from sputtered atoms, which is shown to be negligible in this experiment, but should become measurable in case of materials with high sputtering yields.

  8. Dosimetric Characteristics of Circular 6-MeV X-Ray Beams for Stereotactic Radiotherapy with a Linear Accelerator

    NASA Astrophysics Data System (ADS)

    Wysocka, A.; Rostkowska, J.; Kania, M.; Bulski, W.; Fijuth, J.

    2000-01-01

    Dosimetric characteristics of 6 MeV circular X-ray beams of diameters ranging from 7.5 to 35.0 mm are reported. The 6-MeV X-ray beam from Clinac 2300CD was formed using additional cylindrical BrainLAB's collimators. The mechanical stability of the entire system was verified. Specific quantities measured include tissue maximum ratios (TMR), beam profiles (off-axis ratios OAR) and relative output factors. Measurements of these parameters were performed in a water phantom using small cylindrical ionization chambers and a diamond detector. Comparison of TMR values measured with the ionization chamber and the diamond detector showed no significant differences. It was shown that the latter yields more accurate results for beam profiles than ionization chambers. The mechanical and dosimetric characteristics of this radiotherapy unit are found to be suitable for stereotactic radiosurgery and radiotherapy.

  9. Development of ion transportation, extraction and neutralization systems for atomic beam resonance method

    NASA Astrophysics Data System (ADS)

    Nagae, Daisuke; Asahi, Koichiro; Miyoshi, Hisanori; Shimada, Kenzi; Yoshimi, Akihiro; Ueno, Hideki; Murata, Jiro; Uchida, Makoto; Kameda, Daisuke; Kato, Go; Emori, Shoken; Kijima, Go; Oshima, Sachiko; Takemura, Makoto; Arai, Takemasa; Kobayashi, Yoshio; Haseyama, Tomohito; Schmidt-Ott, W. D.

    2005-11-01

    A device that produces a low-energy and largely spin polarized RI beam based on the atomic beam resonance method (RIABR) has been developed. We have performed measurements of stopping and drifting an incoming RI ion beam in a gas chamber, extraction of the ions into a vacuum region, and neutralization of the extracted low-energy ion beam. The drift efficiency of RI ions in a gas and the extraction efficiency at a Laval-type glass nozzle were found to be 0.72±0.04 and 0.033, respectively. The result of the experiment for the neutralization is also discussed.

  10. Proton beam of 2 MeV 1.6 mA on a tandem accelerator with vacuum insulation

    NASA Astrophysics Data System (ADS)

    Kasatov, D.; Kuznetsov, A.; Makarov, A.; Shchudlo, I.; Sorokin, I.; Taskaev, S.

    2014-12-01

    A source of epithermal neutrons based on a tandem accelerator with vacuum insulation for boron neutron capture therapy of malignant tumors was proposed and constructed. Stationary proton beam with 2 MeV energy, 1.6 mA current, 0.1% energy monochromaticity and 0.5% current stability has just been obtained.

  11. Halo plasma heating by neutral beam injection in TMX-U

    SciTech Connect

    Hsu, W.L.; Bauer, W.; Kerst, R.A.; Wilson, K.L.; Simonen, T.C.; Foote, J.H.; Pickles, W.L.

    1985-05-01

    The electron temperature and density of the halo in TMX-U have been measured by Langmuir probes to study the heating of the halo plasma by neutral beam injection. This study is motivated by the recent interest in using a pair of halo recyclers to enhance the halo density and thereby increase halo shielding. In present TMX-U operation, without halo recyclers, a halo density of 2 x 10/sup 12/ cm/sup -3/ with electron temperature of 20 eV has been measured during the heating phase with neutral beam injection only. A halo power balance model incorporating several heating mechanisms resulting from neutral beam injection is described. The model accurately predicts the measured temperatures. At the halo density range that one expects to achieve with halo recyclers, the model predicts the existing TMX-U neutral beam sources to heat the halo to at least 30 eV.

  12. Neutral beam current driven operation of the DIII-D tokamak

    SciTech Connect

    Simonen, T.C.; Bhadra, D.K.; Burrell, K.H.; Callis, R.W.; Chance, M.S.; Chu, M.S.; Colleraine, A.P.; Greene, J.M.; Groebner, R.J.; Harvey, R.W.; Hill, D.N.; Kim, J.; Lao, L.; Matsuoka, M.; Petersen, P.I.; Porter, G.D.; St. John, H.; Stallard, B.W.; Stambaugh, R.D.; Strait, E.J.; Taylor, T.S.

    1988-03-01

    Neutral beam current drive experiment in the DII-D tokamak with a single null poloidal divertor are described. A plasma current of 0.34 MA has been sustained entirely by neutral beams with H-mode quality energy confinement. Poloidal beta values reach 3.5 without disruption or coherent magnetic activity, suggesting that these plasmas may be entering the second stability regime. 12 refs., 2 figs.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. 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. PMID:26932053

  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. BNL development of H/sup -//D/sup -/ sources for fusion reactor neutral beam lines

    SciTech Connect

    Prelec, K

    1980-01-01

    The long range program of the BNL Neutral Beam Development Group is to design a neutral beam system based on neutralization of negative ions, with an energy of 200 keV or higher, a D/sup -/ beam current of 10 A and operating in pulses of 5 s duration or longer; the beam system would be used on fusion devices for plasma heating. Presently, work is concentrated on the development of an H/sup -/ or D/sup -/ ion source, to deliver about 1 A of beam current, at an energy of at least 10 keV and operating in pulses longer than 5 s. A source of the magnetron type was designed and fabricated and is to be tested soon; the paper describes the background experiments that were necessary for the source design, the source parameters and design features, as well as a method under consideration that would improve the gas efficiency by an order of magnitude.

  17. Laser Wakefield Acceleration of High-Quality Electron Beams to 300 MeV and Efficient Initiation of Photonuclear Reactions

    SciTech Connect

    Reed, S. A.; Naumova, N.; Vane, C Randy; Beene, James R; Bulanov, S. S.; Chvykov, V.; Hou, B.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Schultz, David Robert; Stracener, Daniel W; Yanovsky, V.; Maksimchuk, A.

    2006-11-01

    By focusing 40-TW, 30-fs laser pulses to the intensity of 1019 W/cm2 onto a supersonic He gas jet, we generated quasi-monoenergetic electron beams for plasma density in the narrow range of 1.5<= ne <=3 1019 cm3. We show that the energy, charge, divergence and pointing stability of the beam vary sensitively with ne within this range. The observed variations can be explained physically by the interplay among pump depletion and dephasing between accelerated electrons and plasma wave. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne~1.5 1019 cm3. The quasi-monoenergeic electron beams with energy of 100-150 MeV and charge of 0.5 nC have been used to perform gamma-nuclear photofission of natural uranium targets. Through bremsstrahlung emission, such electron beams are well suited for the efficient generation of high energy (tens of MeV) gamma-rays necessary to induce photofission reactions. Quantitative gamma-ray spectroscopy of the irradiated U sample shows that more than ~105 photonuclear reactions have been produced per Joule of laser energy, which is 10 to 50 times higher than in a previously reported experiments

  18. Laser Wakefield Acceleration of High-Quality Electron Beams to 300 MeV and Efficient Initiation of Photonuclear Reactions

    SciTech Connect

    Reed, S. A.; Naumova, N.; Bulanov, S. S.; Chvykov, V.; Hou, B.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Vane, C. R.; Beene, J. R.; Schultz, D. R.; Stracener, D. W.

    2006-11-27

    By focusing 40-TW, 30-fs laser pulses to the intensity of 1019 W/cm2 onto a supersonic He gas jet, we generated quasi-monoenergetic electron beams for plasma density in the narrow range of 1.5{<=} ne {<=}3x1019 cm3. We show that the energy, charge, divergence and pointing stability of the beam vary sensitively with ne within this range. The observed variations can be explained physically by the interplay among pump depletion and dephasing between accelerated electrons and plasma wave. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne{approx}1.5x1019 cm3. The quasi-monoenergeic electron beams with energy of 100-150 MeV and charge of 0.5 nC have been used to perform {gamma}-nuclear photofission of natural uranium targets. Through bremsstrahlung emission, such electron beams are well suited for the efficient generation of high energy (tens of MeV) {gamma}-rays necessary to induce photofission reactions. Quantitative {gamma}-ray spectroscopy of the irradiated U sample shows that more than {approx}105 photonuclear reactions have been produced per Joule of laser energy, which is 10 to 50 times higher than in a previously reported experiments.

  19. Modified 180/sup 0/ separation magnet for DIII-Big Dee neutral beam injectors

    SciTech Connect

    Hong, R.; Colleraine, A.P.; Fasolo, J.; Kim, J.; Phillips, J.

    1985-07-01

    Neutral beam injection systems for heating the plasma of a fusion research device utilize a deflection magnet to separate the unneutralized residual ions from the neutral particles and steer them into an ion dump. Performance of the separation magnet is crucial in that its failure will cause serious damage to beamline components. A technique using wire orbit simulations was successfully applied to test the performance of the modified 180/sup 0/ separation magnet for DIII-Big Dee neutral beam injectors. It simulated the stable ion trajectories, and showed the fringe field effects and the proper range of operating magnet field strength to be determined.

  20. 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.

  1. 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

  2. Preparation of thin films for use in generating neutral particle beams

    SciTech Connect

    Aaron, W.S.; Zevenbergen, L.A.; Adair, H.L.

    1986-01-01

    Large-area, thin aluminum foils were prepared for use in beam neutralization experiments. The foils were made using either electron beams of resistance heating. Foil thickness and uniformity were determined using alpha particles. The foils perform very well when bombarded by energetic H/sup -/ ions. (DLC)

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  5. 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.

  6. Efficient, radiation-hardened, 400- and 800-keV neutral-beam injection systems

    SciTech Connect

    Anderson, O.A.; Cooper, W.S.; Fink, J.A.; Goldberg, D.A.; Ruby, L.; Soroka, L.; Tanabe, J.

    1983-04-01

    We present designs for two negative-ion based neutral beam lines with reactor-level power output. Both beam lines make use of such technologically advanced features as high-current-density surface-conversion ion sources, transverse-field-focussing (TFF) acceleration and transport, and laser photodetachment. For the second of these designs, we also presented detailed beam and vacuum calculations, as well as a brief description of a proof-of-principle test system currently under development.

  7. Field Ionization of Neutral Litium Vapor Using a 28.5 GeV Electron Beam

    SciTech Connect

    O'Connell, C.L.; Barnes, c.D.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; Krejcik, P.; Siemann, R.; Walz, D.R.; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.; Clayton, C.E.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Zhou, M.; /UCLA

    2006-01-30

    The E164/E164X plasma wakefield experiment studies beam-plasma interactions at the Stanford Linear Acceleration Center (SLAC). Due to SLAC's recent ability to variably compress bunches longitudinally from 650 {micro}m down to 20 {micro}m, the incoming beam is sufficiently dense to field ionize the neutral lithium (Li) vapor. The field ionization effects are characterized by the beams energy loss through the Li vapor column. Experiment results are presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Improvement of surface roughness in silicon-on-insulator wafer fabrication using a neutral beam etching

    NASA Astrophysics Data System (ADS)

    Min, T. H.; Park, B. J.; Kang, S. K.; Gweon, G. H.; Kim, Y. Y.; Yeom, G. Y.

    2009-08-01

    Silicon-on-insulator (SOI) wafers were etched by an energetic chlorine neutral beam obtained by the low-angle forward reflection of an ion beam, and the surface roughness of the etched wafers was compared with that of the SOI wafers etched by an energetic chlorine ion beam. When the ion beam was used to etch the silicon layer of the SOI wafers, the surface roughness was not significantly changed even though the use of higher ion bombardment energy slightly decreased the surface roughness of the SOI wafer. However, when the chlorine neutral beam was used instead of the chlorine ion beam having a similar beam energy, the surface roughness of the SOI wafer was significantly improved compared with that etched by the chlorine ion beam. By etching about 150 nm silicon from the SOI wafer having a 300 nm-thick top silicon layer with the chlorine neutral beam at the energy of 500 eV, the rms surface roughness of 1.5 Å could be obtained with the etch rate of about 750 Å min-1.

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

    SciTech Connect

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

    2014-02-15

    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.