Download or read book New Capabilities for Modeling Intense Beams in Heavy Ion Fusion Drivers written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant advances have been made in modeling the intense beams of heavy-ion beam-driven Inertial Fusion Energy (Heavy Ion Fusion). In this paper, a roadmap for a validated, predictive driver simulation capability, building on improved codes and experimental diagnostics, is presented, as are examples of progress. The Mesh Refinement and Particle-in-Cell methods were integrated in the WARP code; this capability supported an injector experiment that determined the achievable current rise time, in good agreement with calculations. In a complementary effort, a new injector approach based on the merging of (almost equal to)100 small beamlets was simulated, its basic feasibility established, and an experimental test designed. Time-dependent 3D simulations of the High Current Experiment (HCX) were performed, yielding voltage waveforms for an upcoming study of bunch-end control. Studies of collective beam modes which must be taken into account in driver designs were carried out. The value of using experimental data to tomographically ''synthesize'' a 4D beam particle distribution and so initialize a simulation was established; this work motivated further development of new diagnostics which yield 3D projections of the beam phase space. Other developments, including improved modeling of ion beam focusing and transport through the fusion chamber environment and onto the target, and of stray electrons and their effects on ion beams, are briefly noted.
Download or read book New Capabilities for Modeling Intense Beams in Heavy Ion Fusiondrivers written by R. C. Davidson and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SIMULATION OF INTENSE BEAMS FOR HEAVY ION FUSION written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract not provided.
Download or read book Overview of Theory and Modeling in the Heavy Ion Fusion Virtual National Laboratory written by and published by . This book was released on 2002 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents analytical and simulation studies of intense heavy ion beam propagation, including the injection, acceleration, transport and compression phases, and beam transport and focusing in background plasma in the target chamber. Analytical theory and simulations that support the High Current Experiment (HCX), the Neutralized Transport Experiment (NTX), and the advanced injector development program, are being used to provide a basic understanding of the nonlinear beam dynamics and collective processes, and to develop design concepts for the next-step Integrated Beam Experiment (IBX), an Integrated Research Experiment (IRE), and a heavy ion fusion driver. 3-D nonlinear perturbative simulations have been applied to collective instabilities driven by beam temperature anisotropy, and to two-stream interactions between the beam ions and any unwanted background electrons; 3-D particle-in-cell simulations of the 2 MV Electrostatic Quadrupole (ESQ) injector have clarified the influence of pulse rise time; analytical studies and simulations of the drift compression process have been carried out; syntheses of a 4-D particle distribution function from phase-space projections have been developed; and studies of the generation and trapping of stray electrons in the beam self fields have been performed. Particle-in-cell simulations, involving pre-formed plasma, are being used to study the influence of charge and current neutralization on the focusing of the ion beam in NTX and in a fusion chamber.
Download or read book Shaun Clark written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heavy Ion Fusion Science written by R. C. Davidson and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past two years noteworthy experimental and theoretical progress has been made towards the top-level scientific question for the U.S. program in Heavy Ion Fusion Science and High Energy Density Physics: ''How can heavy ion beams be compressed to the high intensity required to create high energy density matter and fusion conditions''? [1]. New results in transverse and longitudinal beam compression, beam-target interaction, high-brightness transport, beam production, as well as a new scheme in beam acceleration will be reported. Longitudinal and Transverse Beam Compression: The Neutralized Transport Experiment (NTX) demonstrated transverse beam density enhancement by a factor greater than 100 when an otherwise space-charge dominated ion beam was neutralized by a plasma source [2]. This experiment was followed by the Neutralized Drift Compression Experiment (NDCX) in which an ion beam was longitudinally compressed by a factor of 50 [3]. This was accomplished by applying a linear head-to-tail velocity ''tilt'' to the beam, and then allowing the beam to drift through a meter-long neutralizing plasma. In both the transverse and longitudinal experiments, extensive 3-D simulations, using LSP, were carried out, and the agreement with experiments was excellent [4]. A three-dimensional kinetic model for longitudinal compression was developed, and it was shown that the Vlasov equation possesses a class of exact solutions for the problem [5]. Beam-Target Interaction: We have also made significant progress in identifying the unique role ion beams can play in heating material to warm dense matter (WDM) conditions. We have identified promising accelerator, beam, and target configurations, as well as new experiments on material properties. It is shown that the target temperature uniformity can be maximized if the ion energy at target corresponds to the maximum in the energy loss rate dE/dX [6]. Ions of moderate energy (a few to tens of MeV) may be used. The energy must be deposited in times much shorter than the hydrodynamic expansion time (ns for metallic foams at 0.01 to 0.1 times solid density). Hydrodynamic simulations [7] have confirmed that uniform conditions with temperature variations of less than a few per cent can be achieved. High-Brightness Transport: Unwanted electrons can lead to deleterious effects for high-brightness ion beam transport. We are studying electron accumulation in quadrupole and solenoid beam transport systems. Electrons can originate from background gas ionization, from beam-tubes struck by ions near grazing incidence, and from end-walls struck by ions near normal incidence [8]. In parallel with the experimental campaign, we have developed and implemented in WARP 3D a new approach to large time-step advancement of electron orbits, as well as a comprehensive suite of models for electrons, gas, and wall interactions [9]. If sufficient electrons are accumulated within the beam, severe distortion of the beam phase space can result. Simulations of this effect have reproduced the key features observed in the experiments. Beam Production: The merging-beamlet injector experiment recently completed demonstrates the feasibility of a compact, high-current injector for heavy ion fusion drivers. In our experiment, 119 argon ion beamlets at 400 keV beam energy were merged into an electrostatic quadrupole channel to form a single beam of 70 mA. The measured unnormalized transverse emittance (phase space area) of 200-250 mm-mrad for the merged beam met fusion driver requirement. These measurements are in good agreement with our particle-in-cell simulations using WARP3D [10]. We have also completed the physics design of a short-pulse injector suitable for WDM studies. Beam Acceleration: A new concept for acceleration, the Pulse Line Ion Accelerator PLIA [11], offers the potential of a very low cost accelerator for WDM studies. It is based on a traveling wave structure, using a simple geometry with a helical conductor. We have obtained experimental verification of the predicted PLIA beam dynamics. Measured energy gain, longitudinal phase space, and beam bunching are in good agreement with WARP3D simulations. Computational Models and Simulator Experiments: The pioneering merger of Adaptive Mesh Refinement and particle-in-cell methods [12] underlies much of the recent success of WARP3D. BEST, the Beam Equilibrium Stability and Transport code was optimized for massively parallel computers and applied to studies of the collective effects of 3D bunched beams [13] and the temperature-anisotropy instability [14]. Space-charge-dominated beam physics experiments relevant to long-path accelerators were carried out on the recently completed University of Maryland Electron Ring, and on the Paul Trap Simulator Experiment at PPPL.
Download or read book Simulation of Intense Beams and Targets for Heavy Ion Fusion Science HEDLP written by and published by . This book was released on 2010 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SIMULATION OF INTENSE BEAMS FOR HEAVY ION FUSION written by A. Friedman and published by . This book was released on 2004 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Beam Simulations for IRE and Driver Status and Strategy written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The methods and codes employed in the U.S. Heavy Ion Fusion program to simulate the beams in an Integrated Research Experiments (IRE) facility and a fusion driver are presented in overview. A new family of models incorporating accelerating module impedance, multi-beam, and self-magnetic effects is described, and initial WARP3d particle simulations of beams using these models are presented. Finally, plans for streamlining the machine-design simulation sequence, and for simulating beam dynamics from the source to the target in a consistent and comprehensive manner, are described.
Download or read book Realistic Modeling of Chamber Transport for Heavy ion Fusion written by and published by . This book was released on 2003 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transport of intense heavy-ion beams to an inertial-fusion target after final focus is simulated here using a realistic computer model. It is found that passing the beam through a rarefied plasma layer before it enters the fusion chamber can largely neutralize the beam space charge and lead to a usable focal spot for a range of ion species and input conditions.
Download or read book Issues and Opportunities written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Beam Dynamics Studies for Heavy Ion Fusion Drivers written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Heavy Ion Beam Images and Comparison to RetardingPotential Analyzer Measurements written by Beth Ellen Rosenberg and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been predicted that world energy demand will soon put enormous pressure on the currently available energy sources. Fusion energy is a potential solution to this problem if it can be controlled and converted into electricity in an economically feasible manner. One type of potential fusion energy plant uses heavy-ion beam drivers for inertial fusion energy. As part of the High Current Experiment (HCX), we seek to understand the injection, transport and focusing of high-current ion beams, by investigating the interactions of background gas and electrons (which can deteriorate the beam quality) with the primary K{sup +} beam. We present here a method of analyzing the electrostatic potential distribution due to the beam space charge within the grounded conducting vacuum pipe. This method enables tracking of ions arising from the ionization of background gas atoms by the incident K{sup +} beam. The beam intensity distribution is obtained from images gathered using a scintillator placed in the beam path. These data are used to calculate the expelled ion energy distribution, which is then compared to data collected from a Retarding Potential Analyzer (RPA). The comparison of the image analysis with RPA measurements is in fair agreement, given model and experimental uncertainties. Some remaining issues to be explored include the apparent correlation of maximum beam potential with RMS beam size, the systematic effect of background subtraction in the images, as well as possible 3D effects. The new method offers an improved capability to investigate and understand the physics of intense beams, furthering the development of a viable heavy-ion driver for an inertial fusion power plant, which is intended to make fusion energy an affordable and environmentally attractive source of electric power.
Download or read book Simulating Intense Ion Beams for Inertial Fusion Energy written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Systems Modeling and Analysis of Heavy Ion Drivers for Inertial Fusion Energy written by and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computer model for systems analysis of heavy ion drivers based on induction linac technology has been used to evaluate driver designs for inertial fusion energy (IFE). Design parameters and estimated costs have been determined for drivers with various ions, different charge states, different front-end designs, with and without beam merging, and various pulse compression and acceleration schedules. We have examined the sensitivity of the results to variations in component cost assumptions, design constraints, and selected design parameters.
Download or read book A New Heavy ion beam Driver Model for the SAFIRE Code written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The heavy-ion-beam driver model that was developed by McDonnell Douglas Astronautics Corporation as part of the Heavy Ion Fusion System Assessment study has been incorporated into the SAFIRE code. The model calculates the cost and performance of an induction linear accelerator and the beam transport systems required to deliver the beam to the fusion chamber. The results are used within the SAFIRE code for economic evaluation of inertial confinement fusion electric power plants. This report briefly describes the subroutines that make up the driver model, defines the variables that were added to the SAFIRE code, and gives an example of the output for a calculation using the new driver model.
