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P K Roy,
S S Yu,
E Henestroza,
A Anders,
F M Bieniosek,
J Coleman,
S Eylon,
W G Greenway, M Leitner,
B G Logan,
W L Waldron,
D R Welch,
C Thoma,
A B Sefkow,
E P Gilson,
P C Efthimion,
R C Davidson
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A Persaud,
J W Kwan, M Leitner,
K-N Leung,
B Ludewigt,
N Tanaka,
W Waldron,
S Wilde,
A J Antolak,
D H Morse,
T Raber
[show abstract]
[hide abstract]
ABSTRACT: A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.
The Review of scientific instruments 02/2010; 81(2):02B904. · 1.52 Impact Factor
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ABSTRACT: VENUS is a third generation electron cyclotron resonance (ECR) ion source, which incorporates a high field superconducting NbTi magnet structure, a 28 GHz gryotron microwave source and a state of the art closed cycle cryosystem. During the decade from initial concept to regular operation, it has demonstrated both the feasibility and the performance levels of this new generation of ECR ion sources and required innovation on magnet construction, plasma chamber design, and beam transport. In this paper, the development, performance, and major innovations are described as well as a look to the potential to construct a fourth generation ECR ion source.
The Review of scientific instruments 02/2010; 81(2):02A201. · 1.52 Impact Factor
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ABSTRACT: The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is currently finalizing the design of NDCX-II, the second phase of the Neutralized Drift Compression Experiment, which will use an ion beam to explore Warm Dense Matter (WDM) and Inertial Fusion Energy (IFE) target hydrodynamics. The ion induction accelerator will include induction cells and Blumleins from the decommissioned Advanced Test Accelerator (ATA) at Lawrence Livermore National Laboratory (LLNL). A test stand has been built at Lawrence Berkeley National Laboratory (LBNL) to test refurbished ATA induction cells and pulsed power hardware for voltage holding and ability to produce various compression and acceleration waveforms. The performance requirements, design modifications, and test results will be presented.
Pulsed Power Conference, 2009. PPC '09. IEEE; 08/2009
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A. B. Sefkow,
R. C. Davidson,
E. P. Gilson,
I. D. Kaganovich,
A. Anders,
J. E. Coleman, M. Leitner,
S. M. Lidia,
P. K. Roy,
P. A. Seidl,
W. L. Waldron,
S. S. Yu,
D. R. Welch
[show abstract]
[hide abstract]
ABSTRACT: The Heavy Ion Fusion Science Virtual National Laboratory has achieved 60-fold longitudinal pulse compression of ion beams on the Neutralized Drift Compression Experiment (NDCX) [
P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005)
]. To focus a space-charge-dominated charge bunch to sufficiently high intensities for ion-beam-heated warm dense matter and inertial fusion energy studies, simultaneous transverse and longitudinal compression to a coincident focal plane is required. Optimizing the compression under the appropriate constraints can deliver higher intensity per unit length of accelerator to the target, thereby facilitating the creation of more compact and cost-effective ion beam drivers. The experiments utilized a drift region filled with high-density plasma in order to neutralize the space charge and current of an ∼ 300 keV K+ beam and have separately achieved transverse and longitudinal focusing to a radius <2 mm and pulse duration <5 ns, respectively. Simulation predictions and recent experiments demonstrate that a strong solenoid (Bz<100 kG) placed near the end of the drift region can transversely focus the beam to the longitudinal focal plane. This paper reports on simulation predictions and experimental progress toward realizing simultaneous transverse and longitudinal charge bunch focusing. The proposed NDCX-II facility would capitalize on the insights gained from NDCX simulations and measurements in order to provide a higher-energy (>2 MeV) ion beam user-facility for warm dense matter and inertial fusion energy-relevant target physics experiments.
Physics of Plasmas 02/2009; 16(5):056701-056701-11. · 2.15 Impact Factor
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W.L. Waldron,
J.J. Barnard,
F.M. Bieniosek,
A. Friedman,
E. Henestroza, M. Leitner,
B.G. Logan,
P.A. Ni,
P.K. Roy,
P.A. Seidl,
W.M. Sharp
[show abstract]
[hide abstract]
ABSTRACT: The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is currently developing design concepts for NDCX-II, the second phase of the Neutralized Drift Compression Experiment, which will use ion beams to explore Warm Dense Matter (WDM) and Inertial Fusion Energy (IFE) target hydrodynamics. The ion induction accelerator will consist of a new short pulse injector and induction cells from the decommissioned Advanced Test Accelerator (ATA) at Lawrence Livermore National Laboratory (LLNL). To fit within an existing building and to meet the energy and temporal requirements of various target experiments, an aggressive beam compression and acceleration schedule is planned. WDM physics and ion-driven direct drive hydrodynamics will initially be explored with 30 nC of lithium ions in experiments involving ion deposition, ablation, acceleration and stability of planar targets. Other ion sources which may deliver higher charge per bunch will be explored. A test stand has been built at Lawrence Berkeley National Laboratory (LBNL) to test refurbished ATA induction cells and pulsed power hardware for voltage holding and ability to produce various compression and acceleration waveforms. Another test stand is being used to develop and characterize lithium-doped aluminosilicate ion sources. The first experiments will include heating metallic targets to 10,000 K and hydrodynamics studies with cryogenic hydrogen targets.
09/2008
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B G Logan,
J J Barnard,
F M Bieniosek,
R H Cohen,
J E Coleman,
R C Davidson,
P C Efthimion,
A Friedman,
E P Gilson,
W G Greenway, [......],
A B Sefkow,
P A Seidl,
W Sharp,
E A Startsev,
J-L Vay,
W L Waldron,
J S Wurtele,
D Welch,
G A Westenskow,
S S Yu
[show abstract]
[hide abstract]
ABSTRACT: During the past two years, the U.S. heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high brightness beam transport, advanced theory and numerical simulations, and heavy ion target designs for fusion. First experiments combining radial and longitudinal compression of intense ion beams propagating through background plasma resulted in on-axis beam densities increased by 700X at the focal plane. With further improvements planned in 2007, these results will enable initial ion beam target experiments in warm dense matter to begin next year at LBNL. We are assessing how these new techniques apply to low-cost modular fusion drivers and higher-gain direct-drive targets for inertial fusion energy.
Journal of Physics Conference Series 06/2008; 112(3):032029.
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[show abstract]
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ABSTRACT: A 2 kA cathode was successfully developed for the DARHT-II injector [1]. Since the DARHT injector cannot be baked and there may be virtual leaks, the local pressure near the cathode was not ideal even though the system pressure was in the 10<sup>-8</sup> Torr range. In a series of experiments using quarter-inch size button cathodes, we showed that gas poisoning was a significant factor in this pressure range. Furthermore we found that the 311-XM (doped with scandium and has an M coating) cathode was less affected by gas poisoning than the 612-M, corresponding to a lower effective work function. Water vapor was found to be the worst contaminant among the various gases that we have tested. With a 6.5rdquo diameter 311-XM cathode, the DARHT-II injector produced > 2 kA corresponding to a current density of 10 A/cm<sup>2</sup>.
Vacuum Electronics Conference, 2008. IVEC 2008. IEEE International; 05/2008
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P.A. Ni,
F. Bieniosek, M. Leitner,
B.G. Logan,
R.M. More,
P.K. Roy,
D.H.H. Hoffmann,
D. Fernengel,
A. Hug,
J. Menzel, [......],
D. Varentsov,
H. Wahl,
M. Kulish,
D.N. Nikolaev,
V.Ya. Ternovoi,
A. Fertman,
A.A. Golubev,
B.Yu. Sharkov,
V. Turtikov,
J.J. Barnard
[show abstract]
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ABSTRACT: This paper presents an overview of the warm-dense-matter physics experiments with intense heavy ion beams that has been carried out at the Gesellschaft fur Schwerionenforschung (GSI), Darmstadt, Germany. These experiments are a joint effort of GSI-Darmstadt, TU-Darmstadt, ITEP-Moscow, IPCP-Chernogolvka and LBNL-Berkeley. In the performed experiments, electron-cooled beam of <sup>238</sup>U<sup>73+</sup> ions with initial ion energy of 350 AMeV has been used. The intense, up to 2.5 - 10<sup>9</sup> ions/bunch, ion pulses have been compressed to 110 ns (FWHM) and focused at the target to a spot down to 150 mum diameter. The beam intensity and the pulse shape have been measured by current transformers installed in front of the target chamber whereas the upper limit for the focal spot size has been determined by recording beam-induced emission of argon gas at ionic spectral lines. It was shown that using intense heavy ion beam that is presently available at GSI and employing the HIHEX beam-target design concept, it is possible to investigate basic thermodynamic and transport properties of HED metal states in the two-phase liquid-gas region and near the critical point.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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P.K. Roy,
P.A. Seidl,
J.J. Barnard,
F.M. Bieniosek,
J.E. Coleman,
R.C. Davidson,
J.A. Duersch,
P. Efthimion,
E.P. Gilson,
J.Y. Jung, M. Leitner,
B.G. Logan,
D. Ogata,
A. Molvik,
A.B. Sefkow,
W.L. Waldron,
D.R. Welch
[show abstract]
[hide abstract]
ABSTRACT: Intense bunches of low-energy heavy ions have been suggested as means to heat targets to the warm dense matter regime (Temperature ~ 0.1 to 10 eV, solid density ~1% to 100%). In order to achieve the required intensity on target, a beam spot radius of approximately 0.5 mm, and pulse duration of 2 ns is required with an energy deposition of approximately 1 J/cm<sup>2</sup>. This translates to a peak beam current of 8 A for 0.4 MeV K+ ions. To increase the beam intensity on target, a plasma-filled high-field solenoid is being studied as a means to reduce the beam spot size from several mm to the sub-mm range. A prototype experiment to demonstrate the required beam dynamics has been built at Lawrence Berkeley National Laboratory. The operating magnetic field of the pulsed solenoid is 8 T. Challenges include suitable injection of the plasma into the solenoid so that the plasma density near the focus is sufficiently high to maintain space- charge neutralization of the ion beam pulse. Initial experimental results are presented.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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F.M. Bieniosek, M. Leitner,
B.G. Logan,
R.M. More,
P.K. Roy,
P. Ni,
J.J. Barnard,
M.K. Covo,
A. Molvik,
L.R. Grisham,
H. Yoneda
[show abstract]
[hide abstract]
ABSTRACT: Warm dense matter (WDM) conditions are to be achieved by combined longitudinal and transverse neutralized drift compression of an intense ion beam pulse to provide a hot spot on a target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using reduced density porous targets. Initial experiments in ion-beam-driven WDM will be at low beam velocity, below the Bragg peak, increasing toward the Bragg peak in subsequent higher-energy accelerators. Initial experiments include a transient darkening experiment and a experiment in porous targets at GSI. Further experiments will explore target temperature and other properties such as electrical conductivity to investigate phase transitions and the critical point.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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[show abstract]
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ABSTRACT: We describe a high-resolution 90-degree cylindrical electrostatic energy analyzer for 1-MeV (singly ionized) heavy ions for experiments in the Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL). By adding a stripping cell, the energy reach of the analyzer can be extended to 2 MeV. This analyzer has high dispersion in a first-order focus with bipolar deflection- plate voltages in the range of plusmn50 kV. We present calculations of vacuum-field beam trajectories, space- charge effects, field errors, and a multipole corrector. The corrector consists of 12 rods arranged in a circle around the beam. Such a corrector has excellent properties as an electrostatic quadrupole, sextupole, or linear combination. The improved energy diagnostic will allow measurements of beam energy spread, such as caused by charge exchange or temperature anisotropy, and better understanding of experimental results in planned longitudinal beam studies. Examples for such experiments include investigations of a beam patching pulser to correct errors in the head and tail of the transported beam bunch, and energy errors derived from ripples in the injector voltage waveform.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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P K Roy,
S S Yu,
W L Waldron,
A Anders,
D Baca,
J J Barnard,
F M Bieniosek,
J Coleman,
R C Davidson,
P C Efthimion, [......],
W G Greenway,
E Henestroza,
I Kaganovich, M Leitner,
B G Logan,
A B Sefkow,
P A Seidl,
W M Sharp,
C Thoma,
D R Welch
[show abstract]
[hide abstract]
ABSTRACT: To create high-energy density matter and fusion conditions, high-power drivers, such as lasers, ion beams, and X-ray drivers, may be employed to heat targets with short pulses compared to hydro-motion. Both high-energy density physics and ion-driven inertial fusion require the simultaneous transverse and longitudinal compression of an ion beam to achieve high intensities. We have previously studied the effects of plasma neutralization for transverse beam compression. The scaled experiment, the Neutralized Transport Experiment (NTX), demonstrated that an initially un-neutralized beam can be compressed transversely to $1 mm radius when charge neutralization by background plasma electrons is provided. Here, we report longitudinal compression of a velocity-tailored, intense, neutralized 25 mA K + beam at 300 keV. 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, enhances the beam peak current by a factor of 50 and produces a pulse duration of about 3 ns. The physics of longitudinal compression, experimental procedure, and the results of the compression experiments are presented. r 2007 Elsevier B.V. All rights reserved.
Nuclear Instruments and Methods in Physics Research A. 01/2007; 577:223-230.
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P A Seidl,
J Armijo,
D Baca,
F M Bieniosek,
J Coleman,
R C Davidson,
P C Efthimion,
A Friedman,
E P Gilson,
D Grote, [......],
B G Logan,
A W Molvik,
D V Rose,
P K Roy,
A B Sefkow,
W M Sharp,
J L Vay,
W L Waldron,
D R Welch,
S S Yu
[show abstract]
[hide abstract]
ABSTRACT: This paper presents plans for neutralized drift compression experiments, precursors to future target heating experiments. The target-physics objective is to study warm dense matter (WDM) using short-duration ($1 ns) ion beams that enter the targets at energies just above that at which dE/dx is maximal. High intensity on target is to be achieved by a combination of longitudinal compression and transverse focusing. This work will build upon recent success in longitudinal compression, where the ion beam was compressed lengthwise by a factor of more than 50 by first applying a linear head-to-tail velocity tilt to the beam, and then allowing the beam to drift through a dense, neutralizing background plasma. Studies on a novel pulse line ion accelerator were also carried out. It is planned to demonstrate simultaneous transverse focusing and longitudinal compression in a series of future experiments, thereby achieving conditions suitable for future WDM target experiments. Future experiments may use solenoids for transverse focusing of un-neutralized ion beams during acceleration. Recent results are reported in the transport of a high-perveance heavy ion beam in a solenoid transport channel. The principal objectives of this solenoid transport experiment are to match and transport a space-charge-dominated ion beam, and to study associated electron-cloud and gas effects that may limit the beam quality in a solenoid transport system. Ideally, the beam will establish a Brillouin-flow condition (rotation at one-half the cyclotron frequency). Other mechanisms that potentially degrade beam quality are being studied, such as focusing-field aberrations, beam halo, and separation of lattice focusing elements.
Nuclear Instruments and Methods in Physics Research A. 01/2007; 57775(52).
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[show abstract]
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ABSTRACT: This report collects information on cathode contaminants we have gathered in the process of operating the LBNL DARHT cathode test stand. Information on contaminants is compiled from several sources. The attachment, ''Practical Aspects of Modern Dispenser Cathodes'', is from Heat Wave Corp. (TB-134) and was originally published in Microwave Journal, September 1979. Cathode contamination depends on both material choices and residual gases. Table 1 of TB-134 lists materials that can poison dispenser cathodes. These include reactive residual gases or vapors such as oxygen, water vapor, benzene, chlorine, fluorine, sulfur, silicon, and most metals other than molybdenum, rhenium, tungsten, and copper. The metals interact with the cathode surface through their vapor pressure. A paper by Nexsen and Turner, J. Appl. Phys. 68, 298-303 (1990) shows the threshold effects of some common residual gases or vapors on cathode performance. The book by Walter H. Kohl, Handbook of Materials and Techniques for Vacuum Devices, also contains useful information on cathodes and poisoning agents. A plot of the vapor pressures and poisoning effect of certain metals (from Kohl) is shown below. Note that the vapor pressure of zinc is 1.1 x 10{sup -8} Torr at 400 K = 127 C, and 2.7 x 10{sup -5} at 500 K = 227 C. By contrast iron reaches a vapor pressure 1 x 10{sup -8} between 800 and 900 C. Therefore it is important to eliminate any brass parts that could exceed a temperature of 100 C. Many structural components of the cathode assembly contain steel. At 500-600 C in an oxygen atmosphere chromium oxide may outgas from the steel. [Cho, et.al., J. Vac. Sci. Technol. A 19, p. 998 (2001)]. Steel may also contain silicon, and sulfur at low concentrations. Therefore use of steel should be limited or avoided at high temperature near the cathode. Materials that should be avoided in the vicinity of the cathode include brass, silver, zinc, non-OFHC copper, silicates, and sulfur-containing lubricants such molybdenum disulfide. Macor is an aluminosilicate-based insulator that is not stable at high temperature. Macor near the cathode should be replaced by a high-temperature insulator such as alumina ceramic. Other insulating materials that contain silicates, such as fiber insulating sleeves, should be avoided. Copper that is not OFHC contains oxygen and other impurities and should be avoided. Lubricating screw coatings should be chosen carefully to have no sulfur content. Common sources of contamination that can cause low emission include water, saliva, silicates such as glass dust, etc. Cathodes should be handled in near clean-room conditions to minimize the amount of water vapor on the cathode surface from breathing, etc. Cathodes should also be stored in such as a way as to avoid contact with materials such as glass dust and water vapor. Attached are plots of SEM data for several test pieces that were taken from the LBNL test stand after activation of the 311x scandate DARHT cathode. Several copper pieces in the anode region were tested, showing the presence of zinc. Two stainless steel nuts coated with a contaminant were also tested. The SEM data indicates the presence of zinc and some sulfur. The zinc has been traced to a brass piece, and the sulfur to the possible use of molybdenum disulfide lubricant on a nut in the system. Finally a swipe of contaminant on the vacuum vessel wall analyzed by a commercial testing laboratory shows again the presence of zinc. In order to improve system cleanliness, we have implemented the following modifications to the test stand: replaced the brass piece with copper-tungsten; replaced Macor insulators with alumina ceramic; used boron nitride lubricant; replaced copper beam stop with OFHC copper; and replaced steel pieces near the cathode where possible with copper or copper-tungsten. A clean fire of high-temperature components and a high-current filament test have shown no evidence to date for contaminants since the modifications.
11/2006;
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[show abstract]
[hide abstract]
ABSTRACT: The three-dimensional, particle-in-cell code WARP has been enhanced to allow end-to-end beam dynamics simulations of the VENUS beam transport system from the extraction region, through a mass-analyzing magnet, and up to a two-axis emittance scanner. This article presents the first results of comparisons between the simulation and experimental data. A helium beam (He+ and He2+) is chosen as an initial comparison beam due to its simple mass spectrum. Although a number of simplifications are made for the initial extracted beam, aberration characteristics appear in simulations that are also present in experimental phase-space current-density measurements. Further, measurements of phase-space tilt indicate that simulations must have little or no space-charge neutralization along the transport system to best agree with experiment. In addition, recent measurements of triangular beam structure immediately after the source are presented. This beam structure is related to the source magnetic confinement fields and will need to be taken into account as the initial beam approximations are lifted.
Review of Scientific Instruments 03/2006; 77(3):03A338-03A338-4. · 1.37 Impact Factor
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P K Roy,
S S Yu,
E Henestroza,
A Anders,
F M Bieniosek,
J Coleman,
S Eylon,
W G Greenway, M Leitner,
B G Logan,
W L Waldron,
D R Welch,
C Thoma,
A B Sefkow,
E P Gilson,
P C Efthimion,
R C Davidson
[show abstract]
[hide abstract]
ABSTRACT: Longitudinal compression of a velocity-tailored, intense neutralized beam at 300 keV, 25 mA 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.
Physical Review Letters 01/2006; 95(23):234801. · 7.37 Impact Factor
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P.K. Roy,
S.S. Yu,
E. Henestroza,
S. Eylon,
W.L. Waldron,
F.M. Bieniosek, M. Leitner,
D. Shuman,
W.G. Greenway,
D.L. Vanecek, [......],
B.G. Logan,
D.R. Welch,
D.V. Rose,
C. Thoma,
R.C. Davidson,
P.C. Efthimion,
I. Kaganovich,
E. Gilson,
A.B. Sefkow,
W.M. Sharp
[show abstract]
[hide abstract]
ABSTRACT: Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first neutralized drift compression experiment, a 280 KeV, 25 mA, K<sup>+</sup>ion beam is longitudinally 50-fold compressed using an induction core to produce a velocity tilt. This compression ratio is measured using various diagnostics.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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A. Friedman,
J.J. Barnard,
D.P. Grote,
D.A. Callahan,
G.J. Caporaso,
R.J. Briggs,
C.M. Celata,
A. Faltens,
E. Henestroza,
I. Kaganovich, [......],
M. Tabak,
C.L. Olson,
G. Penn,
A. Sessler,
J.W. Staples,
J. Wurtele,
T. Renk,
D. Rose,
C. Thoma,
D.R. Welch
[show abstract]
[hide abstract]
ABSTRACT: The Heavy Ion Fusion Virtual National Laboratory is developing the intense ion beams needed to drive matter to the High Energy Density regimes required for Inertial Fusion Energy and other applications. An interim goal is a facility for Warm Dense Matter studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target “foils,” which may in fact be foams with mean densities 1% to 10% of solid. This approach complements that being pursued at GSI Darmstadt, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the beam requirements for Warm Dense Matter experiments. We discuss neutralized drift compression and final focus experiments and modeling. We describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally. Finally, we discuss plans toward a user facility for target experiments.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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[show abstract]
[hide abstract]
ABSTRACT: VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (rare isotope accelerator) front end. The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 200 elA of U 30+ , a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 elA of U 48+ , a low current, very high charge state beam. To achieve those ambitious goals, the VENUS ECR ion source has been designed for optimum operation at 28 GHz. The nominal design fields of the axial magnets are 4 T at injection and 3 T at extraction; the nominal radial design field strength at the plasma chamber wall is 2 T, making VENUS currently the world's most powerful ECR plasma confinement structure. Recently, the six year project has made significant progress. In June 2002, the first plasma was ignited at 18 GHz. During 2003, the VENUS ECR ion source was commissioned at 18 GHz, while preparations for 28 GHz operation were being conducted. In May 2004 28 GHz microwave power has been coupled into the VENUS ECR ion source for the first time. Preliminary per-formance-tests with oxygen, xenon and bismuth at 18 GHz and 28 GHz have shown promising results. Intensities close to or exceeding the RIA requirements have been produced for those few test beams. The paper will briefly describe the design of the VENUS source and its beam analyzing system. Results at 18 GHz and 28 GHz including first emittance measurements will be described.
04/2005; 7725(29).
