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in creator/contributor: "Vay, J-L"

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On the non-invariance of space and time scale ranges under Lorentztransformation, and its implications for the study of relativisticinteractions

We present an analysis which shows that the ranges of space and time scales spanned by a system are not invariant under the Lorentz transformation. This implies the existence of a frame of reference which minimizes an aggregate measure of the range of space and time scales. Such a frame is derived for example cases: free electron laser, laser-plasma accelerator, and particle beam interacting with electron clouds. Implications for experimental, theoretical and numerical studies are discussed. Th… more

Date: January 16, 2007

Creator: Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulation of beams or plasmas crossing at relaticisticvelocity

No Description Available.

Date: November 16, 2007

Creator: Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Large-timestep mover for particle simulations of arbitrarilymagnetized species

For self-consistent ion-beam simulations including electron motion, it is desirable to be able to follow electron dynamics accurately without being constrained by the electron cyclotron timescale. To this end, we have developed a particle-advance that interpolates between full particle dynamics and drift motion. By making a proper choice of interpolation parameter, simulation particles experience physically correct parallel dynamics, drift motion, and gyroradius when the timestep is large compa… more

Date: March 26, 2007

Creator: Cohen, R. H.; Friedman, A.; Grote, D. P. & Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Intense ion beam propagation in a reactor sized chamber

The authors consider the physics of the ballistic transport of intense ion beams in a heavy ion fusion reactor chamber filled with low pressure FLIBE gas. The authors consider first a single beam envelope model and show via a simple case that emittance growth is an issue in the chamber as well as in the accelerator. They develop a model for the neutralization of beam space-charge by the electrons produced by gas ionization by the beam and derive an expression for the evolution of the neutraliza… more

Date: March 17, 2000

Creator: Vay, J. L. & Deutsch, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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AMBER User's Manual

AMBER is a Particle-In-Cell (PIC) code which models the evolution of a representative slice of a relativistic electron beam in a linear accelerator. The beam is modeled as a steady flow and therefore no electromagnetic waves: all the fields (external and self-fields) are electrostatic and magnetostatic fields (for a complete description, see chapter 5). The possible elements describing the accelerator lattice are solenoids, accelerating gaps, pipes and apertures. Several kinds of beam distribut… more

Date: November 8, 2000

Creator: Vay, J. L. & Fawley, W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Noninvariance of Space and Time Scale Ranges under a Lorentz Transformation and the Implications for the Numerical Study of Relativistic Systems

Date: November 12, 2007

Creator: Vay, J. L. & Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of Relativity Lead to"Warp Speed" Computations

A scientist at Lawrence Berkeley National Laboratory has discovered that a previously unnoticed consequence of Einstein's special theory of relativity can lead to speedup of computer calculations by orders of magnitude when applied to the computer modeling of a certain class of physical systems. This new finding offers the possibility of tackling some problems in a much shorter time and with far more precision than was possible before, as well as studying some configurations in every detail for… more

Date: November 1, 2007

Creator: Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

DOD-SBIR Structured Multi-Resolution PIC Code for Electromagnetic Plasma Simulations, Final Report

A novel electromagnetic solver with mesh refinement capability was implemented in Warp. The solver allows for calculations in 2-1/2 and 3 dimensions, includes the standard Yee stencil, and the Cole-Karkkainen stencil for lower numerical dispersion along the principal axes. Warp implementation of the Cole-Karkkainen stencil includes an extension to perfectly matched layers (PML) for absorption of waves, and is preserving the conservation property of charge conserving current deposition schemes, … more

Date: April 22, 2010

Creator: Vay, J. L.; Grote, D. P. & Friedman, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

The WARP Code: Modeling High Intensity Ion Beams

The Warp code, developed for heavy-ion driven inertial fusion energy studies, is used to model high intensity ion (and electron) beams. Significant capability has been incorporated in Warp, allowing nearly all sections of an accelerator to be modeled, beginning with the source. Warp has as its core an explicit, three-dimensional, particle-in-cell model. Alongside this is a rich set of tools for describing the applied fields of the accelerator lattice, and embedded conducting surfaces (which are… more

Date: December 9, 2004

Creator: Grote, D. P.; Friedman, A.; Vay, J. L. & Haber, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Simulation of e-cloud driven instability and its attenuation using a simulated feedback system in the CERN SPS

Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS, and a feedback system to control the single-bunch instabilities is under active development. We present the latest improvements to the WARP-POSINST simulation framework and feedback model, and its application to the self-consistent simulations of two consecutive bunches interacting with an electron cloud in the SPS. Simulations using an idealized feedback system exhibit adequate mitigat… more

Date: December 13, 2010

Creator: Vay, J. L. & Furman, M. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Formation of High Charge State Heavy Ion Beams with intense Space Charge

High charge-state heavy-ion beams are of interest and used for a number of accelerator applications. Some accelerators produce the beams downstream of the ion source by stripping bound electrons from the ions as they pass through a foil or gas. Heavy-ion inertial fusion (HIF) would benefit from low-emittance, high current ion beams with charge state >1. For these accelerators, the desired dimensionless perveance upon extraction from the emitter is {approx}10{sup -3}, and the electrical curre… more

Date: March 1, 2011

Creator: Seidl, P. A. & Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Use of the Lorentz-Boosted Frame Transformation to Simulate Free-Electron Laser Amplifier Physics

Recently [1]it has been pointed out that numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz boosted frame. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy (E0>_ 250 MeV) electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor gamma F, the red-shifted FEL radi… more

Date: July 27, 2008

Creator: Fawley, W. M. & Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2

One of the options considered for future upgrades of the LHC injector complex entails the replacement of the PSwith the PS2, a longer circumference and higher energy synchrotron. Electron cloud effects represent an importantpotential limitation to the achievement of the upgrade goals. We report the results of numerical studies aimingat estimating the e-cloud density thresholds for the occurrence of single bunch instabilities.

Date: October 8, 2010

Creator: Venturini, M.; Furman, M. & Vay, J. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

HINS R&D Collaboration on Electron Cloud Effects: Midyea rReport

We present a report on ongoing activities on electron-cloud R&D for the MI upgrade. These results update and extend those presented in Refs. 1, 2. In this report we have significantly expanded the parameter range explored in bunch intensity Nb, RMS bunch length {sigma}{sub z} and peak secondary emission yield (SEY) {delta}{sub max}, but we have constrained our simulations to a field-free region. We describe the threshold behaviors in all of the above three parameters. For {delta}{sub max} {… more

Date: November 7, 2006

Creator: Furman, M. A.; Sonnad, K. & Vay, J. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positiv… more

Date: March 1, 2011

Creator: Vay, J. L.; Furman, M. A. & Venturini, M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Note on numerical study of the beam energy spread in NDCX-I

The kinetic energy spread (defined here as the standard deviation of the beam particle energies) sets the ultimate theoretical limit on the longitudinal compression that can be attained on NDCX-I and NDCX-II. Experimental measurements will inevitably include the real influences on the longitudinal phase space of the beam due to injector and accelerator field imperfections1. These induced energy variations may be the real limit to the longitudinal compression in an accelerator. We report on a nu… more

Date: January 19, 2011

Creator: Vay, J. L.; Seidl, P. A. & Friedman, A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Progress in the study of mesh refinement for particle-in-cell plasma simulations and its application to heavy ion fusion

The numerical simulation of the driving beams in a heavy ion fusion power plant is a challenging task, and, despite rapid progress in computer power, one must consider the use of the most advanced numerical techniques. One of the difficulties of these simulations resides in the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g. fluid dynamics sim… more

Date: September 15, 2002

Creator: Vay, J. L.; Friedman, A. & Grote, D. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Asymmetric PML for the absorption of waves. Application to mesh refinement in electromagnetic particle-in-cell plasma simulations

We present an extension of the Berenger Perfectly Matched Layer with additional terms and tunable coefficients which introduce some asymmetry in the absorption rate. We show that the discretized version of the new PML offers superior absorption rates than the discretized standard PML under a plane wave analysis. Taking advantage of the high rates of absorption of the new PML, we have devised a new strategy for introducing the technique of Mesh Refinement into electromagnetic Particle-In-Cell pl… more

Date: September 24, 2003

Creator: Vay, J. L.; Adam, J. C. & Heron, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Particle-in-Cell Calculationsof the Electron Cloud in the ILCPositron Damping Ring Wigglers

The self-consistent code suite WARP-POSINST is being used to study electron cloud effects in the ILC positron damping ring wiggler. WARP is a parallelized, 3D particle-in-cell code which is fully self-consistent for all species. The POSINST models for the production of photoelectrons and secondary electrons are used to calculate electron creation. Mesh refinement and a moving reference frame for the calculation will be used to reduce the computer time needed by several orders of magnitude. We p… more

Date: July 1, 2007

Creator: Celata, C. M.; Furman, M. A.; Vay, J. L. & Grote, D. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Novel Methods in the Particle-In-Cell Accelerator Code-Framework Warp

The Particle-In-Cell (PIC) Code-Framework Warp is being developed by the Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) to guide the development of accelerators that can deliver beams suitable for high energy density experiments and implosion of inertial fusion capsules. It is also applied in various areas outside the Heavy Ion Fusion program to the study and design of existing and next-generation high-energy accelerators, including the study of electron cloud effects and laser… more

Date: September 1, 2011

Creator: Vay, J. L.; Grote, D. P.; Cohen, R. H.; Friedman, A.; Grote, D. P.; Cohen, R. H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An Implicit "Drift-Lorentz" Particle Mover for Plasma and Beam Simulations

In order to efficiently perform particle simulations in systems with widely varying magnetization, we 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 have with fu… more

Date: July 15, 2008

Creator: Friedman, A.; Grote, D. P.; Vay, J. L. & Cohen, R. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Heavy Ion Fusion Science Virtual National Laboratory1st Quarter FY08 Milestone Report: Report Initial Work on Developing Plasma Modeling Capability in WARP for NDCX ExperimentsReport Initial work on developing Plasma Modeling Capability in WARP for NDCX Experiments

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 10, 2007

Creator: Friedman, A.; Cohen, R. H.; Grote, D. P. & Vay, J. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A method for obtaining three-dimensional computation equilibrium of non-neutral plasmas using WARP

Computer simulation studies of the stability and transport properties of trapped non-neutral plasmas require the numerical realization of a three-dimensional plasma distribution. This paper presents a new numerical method for obtaining, without an explicit model for physical collisions in the code, a low noise three-dimensional computational equilibrium distribution. This requires both the loading of particles into an idealized distribution and the relaxation from that distribution toward an ap… more

Date: March 25, 2006

Creator: Wurtele, J.; Wurtele, J.; Friedman, A.; Grote, D. P.; Vay, J. L. & Gomberoff, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

Computer simulations using the 2D code"POSINST" were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was l… more

Date: September 2, 2008

Creator: Celata, C. M.; Furman, Miguel A.; Vay, J. L. & Yu, Jennifer W.

Item Type: Article

Partner: UNT Libraries Government Documents Department