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Friedman, A
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2002
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2002
AbstractAbstract
[en] This article provides an overview of current U.S. research on accelerators for Heavy Ion Fusion, that is, inertial fusion driven by intense beams of heavy ions with the goal of energy production. The concept, beam requirements, approach, and major issues are introduced. An overview of a number of new experiments is presented. These include: the High Current Experiment now underway at Lawrence Berkeley National Laboratory; studies of advanced injectors (and in particular an approach based on the merging of multiple beamlets), being investigated experimentally at Lawrence Livermore National Laboratory; the Neutralized (chamber) Transport Experiment being assembled at Lawrence Berkeley National Laboratory; and smaller experiments at the University of Maryland and at Princeton Plasma Physics Laboratory. The comprehensive program of beam simulations and theory is outlined. Finally, prospects and plans for further development of this promising approach to fusion energy are discussed
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1 Sep 2002; 16 p; Advanced Accelerator Concepts Workshop; Oxnard, CA (United States); 23-28 Jun 2002; W--7405-ENG-48; Available from PURL: https://www.osti.gov/servlets/purl/15013431-WOFQzA/native/
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Friedman, A
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2004
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2004
AbstractAbstract
[en] Computer simulations of intense ion beams play a key role in the Heavy Ion Fusion research program. Along with analytic theory, they are used to develop future experiments, guide ongoing experiments, and aid in the analysis and interpretation of experimental results. They also afford access to regimes not yet accessible in the experimental program. The U.S. Heavy Ion Fusion Virtual National Laboratory and its collaborators have developed state-of-the art computational tools, related both to codes used for stationary plasmas and to codes used for traditional accelerator applications, but necessarily differing from each in important respects. These tools model beams in varying levels of detail and at widely varying computational cost. They include moment models (envelope equations and fluid descriptions), particle-in-cell methods (electrostatic and electromagnetic), nonlinear-perturbative descriptions (''(delta)f''), and continuum Vlasov methods. Increasingly, it is becoming clear that it is necessary to simulate not just the beams themselves, but also the environment in which they exist, be it an intentionally-created plasma or an unwanted cloud of electrons and gas. In this paper, examples of the application of simulation tools to intense ion beam physics are presented, including support of present-day experiments, fundamental beam physics studies, and the development of future experiments. Throughout, new computational models are described and their utility explained. These include Mesh Refinement (and its dynamic variant, Adaptive Mesh Refinement); improved electron cloud and gas models, and an electron advance scheme that allows use of larger time steps; and moving-mesh and adaptive-mesh Vlasov methods
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10 Jun 2004; vp; 15. International Symposium on Heavy Ion Inertial Fusion; Princeton, NJ (United States); 7-11 Jun 2004; W-7405-ENG-48; Available from http://www.llnl.gov/tid/lof/documents/pdf/308579.pdf; PURL: https://www.osti.gov/servlets/purl/15014309-X3bmxT/native/; PDF-FILE: 9 ; SIZE: 1.9 MBYTES
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Friedman, A.
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE National Nuclear Security Administration (United States)2001
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE National Nuclear Security Administration (United States)2001
AbstractAbstract
[en] The Heavy Ion Fusion (HIF) program's goal is the development of the body of knowledge needed for Inertial Fusion Energy (IFE) to realize its promise. The intense ion beams that will drive HIF targets are nonneutral plasmas and exhibit collective, nonlinear dynamics which must be understood using the kinetic models of plasma physics. This beam physics is both rich and subtle: a wide range in spatial and temporal scales is involved, and effects associated with both instabilities and non-ideal processes must be understood. Ion beams have a ''long memory,'' and initialization of a beam at mid-system with an idealized particle distribution introduces uncertainties; thus, it will be crucial to develop, and to extensively use, an integrated and detailed ''source-to-target'' HIF beam simulation capability. We begin with an overview of major issues
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20 Feb 2001; 749 Kilobytes; W--7405-ENG-48; Available from PURL: https://www.osti.gov/servlets/purl/798779-kJSEgD/native/
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Friedman, A
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE Office of Energy Research (ER) (United States)1999
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE Office of Energy Research (ER) (United States)1999
AbstractAbstract
[en] UCRL- JC- 134975 PREPRINT code offering 3- D, axisymmetric, and ''transverse slice'' (steady flow) geometries, with a hierarchy of models for the ''lattice'' of focusing, bending, and accelerating elements. Interactive and script- driven code steering is afforded through an interpreter interface. The code runs with good parallel scaling on the T3E. Detailed simulations of machine segments and of complete small experiments, as well as simplified full- system runs, have been carried out, partially benchmarking the code. A magnetoinductive model, with module impedance and multi- beam effects, is under study. experiments, including an injector scalable to multi- beam arrays, a high- current beam transport and acceleration experiment, and a scaled final- focusing experiment. These ''phase I'' projects are laying the groundwork for the next major step in HIF development, the Integrated Research Experiment (IRE). Simulations aimed directly at the IRE must enable us to: design a facility with maximum power on target at minimal cost; set requirements for hardware tolerances, beam steering, etc.; and evaluate proposed chamber propagation modes. Finally, simulations must enable us to study all issues which arise in the context of a fusion driver, and must facilitate the assessment of driver options. In all of this, maximum advantage must be taken of emerging terascale computer architectures, requiring an aggressive code development effort. An organizing principle should be pursuit of the goal of integrated and detailed source- to- target simulation. methods for analysis of the beam dynamics in the various machine concepts, using moment- based methods for purposes of design, waveform synthesis, steering algorithm synthesis, etc. Three classes of discrete- particle models should be coupled: (1) electrostatic/ magnetoinductive PIC simulations should track the beams from the source through the final- focusing optics, passing details of the time- dependent distribution function to (2) electromagnetic or magnetoinductive PIC or hybrid PIG/ fluid simulations in the fusion chamber (which would finally pass their particle trajectory information to the radiation- hydrodynamics codes used for target design); in parallel, (3) detailed PIC, delta- f, core/ test- particle, and perhaps continuum Vlasov codes should be used to study individual sections of the driver and chamber very carefully; consistency may be assured by linking data from the PIC sequence, and knowledge gained may feed back into that sequence
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15 Jul 1999; 474 Kilobytes; 1999 Fusion Summer Study; Snowmass, CO (United States); 12-23 Jul 1999; AT--5015031; W-7405-ENG-48; Available from PURL: https://www.osti.gov/servlets/purl/11314-XlXlsP/native/
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Friedman, A
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2006
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2006
AbstractAbstract
[en] The Pulse-Line Ion Accelerator (PLIA) is a promising approach to high-gradient acceleration of an ion beam at high line charge density [1, 2, 3, 4, 5, 6]. A recent note by R. J. Briggs [7] suggests that a ''sheath helix'' model of such a system can be solved numerically in the quasi-static limit. Such a model captures the correct macroscopic behavior from ''first principles'' without the need to time-advance the full Maxwell equations on a grid. This note describes numerical methods that may be used to effect such a solution, and their connection to the circuit model that was described in an earlier note by the author [8]. Fine detail of the fields in the vicinity of the helix wires is not obtained by this approach, but for purposes of beam dynamics simulation such detail is not generally needed
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1 Feb 2006; 10 p; W-7405-ENG-48; Available from http://www.llnl.gov/tid/lof/documents/pdf/330006.pdf; PURL: https://www.osti.gov/servlets/purl/893987-kEOuEc/; PDF-FILE: 10 ; SIZE: 0.1 MBYTES
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Friedman, A
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2005
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2005
AbstractAbstract
[en] This note describes a simple model developed to explore some of the properties of the pulse-line ion accelerator [1], here represented as a series of lumped elements, in the general parameter regime for the ''NDCX-1d'' experiments. The goals of this modeling are: to understand the evolution of various possible input pulses in the presence of dispersive effects and imperfect termination of the line; to examine scenarios for beam acceleration; and to explore the effects of ''beam loading'', that is, changes to the voltages along the helical line that result from the interaction of the beam's return current with the ''circuitry'' of that line. In Section 1 below, the model is described and the method of solution outlined; in Section 2, a low-current example of beam acceleration is presented; in Section 3, runs are presented showing the development of beam loading-induced voltages as model pulses are followed; in section 4, the modeling of a higher-current beam under acceleration is presented, and the effects of beam loading quantified; and in section 5, a brief summary of complementary efforts and of plans to extend the modeling is presented
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8 Mar 2005; 0.4 Megabytes; W-7405-ENG-48; Available from PURL: https://www.osti.gov/servlets/purl/15011518-0oDKaA/native/
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Friedman, A.
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE, Washington, DC (United States)1996
Lawrence Livermore National Lab., CA (United States). Funding organisation: USDOE, Washington, DC (United States)1996
AbstractAbstract
[en] Inertial confinement fusion driven by beams of heavy ions is an attractive route to controlled fusion. In the U.S., induction accelerators are being developed as open-quotes driversclose quotes for this process. This paper is divided into two main sections. In the first section, the concept of induction-accelerator driven heavy-ion fusion is briefly reviewed, and the U.S. program of experiments and theoretical investigations is described. In the second, a open-quotes taxonomyclose quotes of space-charge-dominated beam physics issues is presented, accompanied by a brief discussion of each area
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26 Jan 1996; 28 p; 8. International Committee for Future Accelerators (ICFA) advanced beam dynamics workshop on space charge dominated beams and applications of high brightness beams; Bloomington, IN (United States); 11-13 Oct 1995; CONF-9510263--13; CONTRACT W-7405-ENG-48; Also available from OSTI as DE96011004; NTIS; US Govt. Printing Office Dep
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Friedman, A.
Brookhaven National Lab., Upton, NY (USA). Funding organisation: USDOE, Washington, DC (USA)1991
Brookhaven National Lab., Upton, NY (USA). Funding organisation: USDOE, Washington, DC (USA)1991
AbstractAbstract
[en] A deterministic approach is taken to study the effect of errors in the wiggler magnet field on the spontaneous emission and the gain of Free Electron Lasers. A 3D formulation is used to derive the reduction in spontaneous emission due to changes in the time of flight of the electrons. A generalization of Madey's theorem to 3D is then used to calculate the reduction in the FEL small gain. 6 refs
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1991; 3 p; 1991 Institute of Electrical and Electronics Engineers (IEEE) particle accelerator conference (PAC); San Francisco, CA (USA); 6-9 May 1991; CONF-910505--165; CONTRACT AC02-76CH00016; OSTI as DE91013534; NTIS; INIS; US Govt. Printing Office Dep
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Friedman, A.; Kwan, J.
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2009
Lawrence Livermore National Lab., Livermore, CA (United States). Funding organisation: US Department of Energy (United States)2009
AbstractAbstract
[en] Earlier this year, the U.S. Department of Energy Office of Fusion Energy Sciences approved the NDCX-II project, a second-generation Neutralized Drift Compression eXperiment. NDCX-II is a collaborative effort of scientists and engineers from Lawrence Berkeley National Laboratory (LBNL), Lawrence Livermore National Laboratory (LLNL), and the Princeton Plasma Physics Laboratory (PPPL), in a formal collaboration known as the Virtual National Laboratory for Heavy Ion Fusion Science (HIFS-VNL). Supported by $11 M of funding from the American Recovery and Reinvestment Act, construction at LBNL commenced in July of 2009, with completion anticipated in March of 2012. Applications of this facility will include studies of: the basic physics of the poorly understood 'warm dense matter' regime of temperatures around 1 eV and densities near solid, using uniform, volumetric ion heating of thin foil targets; ion energy coupling into an ablating plasma (such as that which occurs in an inertial fusion target) using beams with time-varying kinetic energy; space-charge-dominated ion beam dynamics; and beam focusing and pulse compression in neutralizing plasma. The machine will complement facilities at GSI in Darmstadt, Germany, but will employ lower ion kinetic energies and commensurately shorter stopping ranges in matter. Much of this research will contribute directly toward the collaboration's ultimate goal of electric power production via heavy-ion beam-driven inertial confinement fusion ('Heavy-Ion Fusion', or HIF). In inertial fusion, a target containing fusion fuel is heated by energetic 'driver' beams, and undergoes a miniature thermonuclear explosion. Currently the largest U.S. research program in inertial confinement is at Livermore's National Ignition Facility (NIF), a multibillion-dollar, stadium-sized laser facility optimized for studying physics issues relevant to nuclear stockpile stewardship. Nonetheless, NIF is expected to establish the fundamental feasibility of fusion ignition on the laboratory scale, and thus advance this approach to fusion energy. Heavy ion accelerators have a number of attributes (such as efficiency, longevity, and use of magnetic fields for final focusing) that make them attractive candidates as Inertial Fusion energy (IFE) drivers As with LBNL's existing NDCX-I, the new machine will produce short ion pulses using the technique of neutralized drift compression. A head-to-tail velocity gradient is imparted to the beam, which then shortens as it drifts in neutralizing plasma that suppresses space-charge forces. NDCX-II will make extensive use of induction cells and other hardware from the decommissioned ATA facility at LLNL. Figure (1) shows the layout of the facility, to be sited in LBNL's Building 58 alongside the existing NDCX-I apparatus. This second-generation facility represents a significant upgrade from the existing NDCX-I. It will be extensible and reconfigurable; in the configuration that has received the most emphasis, each NDCX-II pulse will deliver 30 nC of ions at 3 MeV into a mm-scale spot onto a thin-foil target. Pulse compression to ∼ 1 ns occurs in the accelerator as well as in the drift compression line; the beam is manipulated using suitably tailored voltage waveforms in the accelerating gaps. NDCX-II employs novel beam dynamics. To use the 200 kV Blumlein power supplies from ATA (blue cylinders in the figure), the pulse duration must first be reduced to less than 70 ns. This shortening is accomplished in an initial stage of non-neutral drift compression, downstream of the injector and the first few induction cells. The compression is sufficiently rapid that fewer than ten long-pulse waveform generators are needed, with Blumleins powering the rest of the acceleration. Extensive simulation studies have enabled an attractive physics design; these employ both a new 1-D code (ASP) and the VNL's workhorse 2-D/3-D code Warp. Snapshots from a simulation movie (available online) appear in Fig. 2. Studies on a dedicated test stand are quantifying the performance of the ATA hardware and of pulsed solenoids that will provide transverse beam confinement (ions require much stronger fields than the electrons accelerated by ATA). For more information, see the recent article in the Berkeley Lab News and references therein. Joe Kwan is the NDCX-II project manager and Alex Friedman is the leader for the physics design.
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22 Oct 2009; 3 p; W-7405-ENG-48; Available from https://e-reports-ext.llnl.gov/pdf/380369.pdf; PURL: https://www.osti.gov/servlets/purl/967743-JNwft7/; PDF-FILE: 3; SIZE: 1.4 MBYTES; doi 10.2172/967743
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BEAM DYNAMICS, COMPRESSION, CONFINEMENT, ELECTRIC POWER, HEAVY ION ACCELERATORS, HEAVY IONS, INERTIAL CONFINEMENT, ION BEAMS, KINETIC ENERGY, MAGNETIC FIELDS, PHYSICS, PLASMA, POWER SUPPLIES, RESEARCH PROGRAMS, SPACE CHARGE, THERMONUCLEAR EXPLOSIONS, THERMONUCLEAR FUELS, THERMONUCLEAR REACTORS, WAVE FORMS
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Physical Review Letters; v. 30(3); p. 102-105
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ALPHA DECAY RADIOISOTOPES, BEAMS, CHARGED PARTICLES, DIRECT REACTIONS, ENERGY RANGE, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, HEAVY NUCLEI, ION BEAMS, ISOTOPES, KINETICS, MEV RANGE, NUCLEAR REACTIONS, NUCLEI, ODD-EVEN NUCLEI, PARTICLE BEAMS, PLUTONIUM ISOTOPES, RADIOISOTOPES, REACTION KINETICS, SPECTRA, YEARS LIVING RADIOISOTOPES
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