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New experimental measurements of electron clouds in ion beams with large tune depression

Description: We study electron clouds in high perveance beams (K = 8E-4) with a large tune depression of 0.2 (defined as the ratio of a single particle oscillation response to the applied focusing fields, with and without space charge). These 1 MeV, 180 mA, K+ beams have a beam potential of +2 kV when electron clouds are minimized. Simulation results are discussed in a companion paper [J-L. Vay, this Conference]. We have developed the first diagnostics that quantitatively measure the accumulation of electro… more
Date: March 16, 2006
Creator: Molvik, A W; Covo, M K; Cohen, R H; Friedman, A; Bieniosek, F M; Leister, C M et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Initial Self-Consistent 3D Electron-Cloud Simulations of the LHC Beam with the Code WARP+POSINST

Description: We present initial results for the self-consistent beam-cloud dynamics simulations for a sample LHC beam, using a newly developed set of modeling capability based on a merge [1] of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP [2] and the electron-cloud code POSINST [3]. Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cl… more
Date: October 11, 2005
Creator: Vay, J; Furman, M A; Cohen, R H; Friedman, A & Grote, D P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Report Initial Work on Developing Plasma Modeling Capability in WARP for NDCX Experiments

Description: This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) has developed and implemented an initial beam-in-plasma implicit modeling capability in Warp; has carried out tests validating the behavior of the models employed; has compared the results of electrostatic and electromagnetic models when applied to beam expansion in an NDCX-I relevant regime; has compared Warp and LSP results on a problem relevant to NDCX-I; has modeled wave excitation by a… more
Date: December 14, 2007
Creator: Friedman, A; Cohen, R H; Grote, D P & Vay, J
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

Description: Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment, theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP and the electron cloud code POSINST, with additional functionalities. The development of the new capabi… more
Date: October 11, 2005
Creator: Vay, J; Furman, M A; Seidl, P A; Cohen, R H; Friedman, A; Grote, D P et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation studies of non-neutral plasma equilibria in an electrostatic trap with a magnetic mirror

Description: The equilibrium of an infinitely long, strongly magnetized, non-neutral plasma confined in a Penning-Malmberg trap with an additional mirror coil has been solved analytically [J. Fajans, Phys. Plasmas 10, 1209 (2003)] and shown to exhibit unusual features. Particles not only reflect near the mirror in the low field region, but also may be weakly trapped in part of in the high field region. The plasma satisfies a Boltzmann distribution along field lines; however, the density and the potential va… more
Date: June 5, 2006
Creator: Gomberoff, K; Fajans, J; Wurtele, J; Friedman, A; Grote, D P; Cohen, R H et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Partially-Corrected Euler Method for Solution of ODE's

Description: The authors goal is to solve the ODE: dy/dt = f(t,y(t)) where we are to advance the independent variables y by marching forward in time t using a step size h. Here time levels are denoted by subscripts. The 'modified Euler' method (e.g., [1,2]) uses a forward-Euler step as a predictor to yield a provisional estimate {tilde y}{sub i+1} of the dependent variables at the advanced time level: {tilde y}{sub i+1} = y{sub i} + hf(t{sub i},y{sub i}).
Date: September 27, 2007
Creator: Friedman, A
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Inertial Fusion Energy Studies on an Earth Simulator-Class Computer

Description: The U.S. is developing fusion energy based on inertial confinement of the burning fusion fuel, as a complement to the magnetic confinement approach. DOE's Inertial Fusion Energy (IFE) program within the Office of Fusion Energy Sciences (OFES) is coordinated with, and gains leverage from, the much larger Inertial Confinement Fusion program of the National Nuclear Security Administration (NNSA). Advanced plasma and particle beam simulations play a major role in the IFE effort, and the program is … more
Date: August 13, 2002
Creator: Friedman, A & Stephens, R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Beam Simulations for IRE and Driver - Status and Strategy

Description: 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 f… more
Date: March 13, 2001
Creator: Friedman, A; Grote, D P & Lee, E P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electron-Cloud Simulation and Theory for High-Current Heavy-Ion Beams

Description: Stray electrons can arise in positive-ion accelerators for heavy ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary- electron emission. We summarize the distinguishing features of electron cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds. We also present results from several ingredients in thi… more
Date: July 26, 2004
Creator: Cohen, R; Friedman, A; Lund, S; Molvik, A; Lee, E; Azevedo, T et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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An Implicit "Drift-Lorentz" Particle Mover for Plasma and Beam Simulations

Description: In order to efficiently perform particle simulations in systems with widely varying magnetization, we have developed a 'drift-Lorentz mover', which interpolates between full particle dynamics and drift kinetics in such a way as to preserve a physically correct gyroradius and particle drifts for both large and small ratios of the timestep to the cyclotron period. In order to extend applicability of the mover to systems with plasma frequency exceeding the cyclotron frequency - such as one may hav… more
Date: March 7, 2008
Creator: Cohen, R H; Friedman, A; Grote, D P & Vay, J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Heavy Ion Inertial Fusion Energy: Summaries of Program Elements

Description: The goal of the Heavy Ion Fusion (HIF) Program is to apply high-current accelerator technology to IFE power production. Ion beams of mass {approx}100 amu and kinetic energy {>=} 1 GeV provide efficient energy coupling into matter, and HIF enjoys R&D-supported favorable attributes of: (1) the driver, projected to be robust and efficient; see 'Heavy Ion Accelerator Drivers.'; (2) the targets, which span a continuum from full direct to full indirect drive (and perhaps fast ignition), and ha… more
Date: February 28, 2011
Creator: Friedman, A; Barnard, J J; Kaganovich, I; Seidl, P A; Briggs, R J; Faltens, A et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Solving the quasi-static field model of the pulse-line accelerator; relationship to a circuit model

Description: 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… more
Date: February 1, 2006
Creator: Friedman, A
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modeling the Pulse Line Ion Accelerator (PLIA): an algorithm for quasi-static field solution.

Description: The Pulse-Line Ion Accelerator (PLIA) is a helical distributed transmission line. A rising pulse applied to the upstream end appears as a moving spatial voltage ramp, on which an ion pulse can be accelerated. This is a promising approach to acceleration and longitudinal compression of an ion beam at high line charge density. In most of the studies carried out to date, using both a simple code for longitudinal beam dynamics and the Warp PIC code, a circuit model for the wave behavior was employe… more
Date: June 18, 2007
Creator: Friedman, A; Briggs, R J; Grote, D P; Henestroza, E & Waldron, W L
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Absolute Measurement of Electron Cloud Density

Description: Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge poten… more
Date: June 21, 2007
Creator: Covo, M K; Molvik, A W; Cohen, R H; Friedman, A; Seidl, P A; Logan, G et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Overview of Theory and Simulations in the Heavy Ion Fusion Science Virtual National Laboratory

Description: The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is a collaboration of Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, and Princeton Plasma Physics Laboratory. These laboratories, in cooperation with researchers at other institutions, are carrying out a coordinated effort to apply intense ion beams as drivers for studies of the physics of matter at extreme conditions, and ultimately for inertial fusion energy. Progress on this endeavor depends u… more
Date: July 3, 2006
Creator: Friedman, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparison of Electron Cloud Simulation and Experiments in the High-Current Experiment

Description: Contaminating clouds of electrons are a common concern for accelerators of positive-charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly, weakly, and un-magnetized. We describe our approach to such s… more
Date: November 11, 2004
Creator: Cohen, R H; Friedman, A; Covo, M K; Lund, S M; Molvik, A W; Bieniosek, F M et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electron Cloud Measurements in Heavy-Ion Driver for HEDP and Inertial Fusion Energy

Description: The High Current Experiment (HCX) at LBNL is a driver scale single beam injector that provides a 1 MeV K+ ion beam current of 0.18 A for 5 {micro}s. It transports high-current beams with large fill factor (ratio of the maximum beam envelope radius to the beam pipe radius) and low emittance growth that are required to keep the cost of the power plant competitive and to satisfy the target requirements of focusing ion beams to high-power density. Beam interaction with the background gas and walls … more
Date: August 16, 2006
Creator: Covo, M K; Molvik, A W; Friedman, A; Cohen, R; Vay, J; Bieniosek, F et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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