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Title: Collective temperature anisotropy instabilities in intense charged particle beams

Abstract

The classical electrostatic Harris instability and the electromagnetic Weibel instability, both driven by a large temperature anisotropy (T{sub parallelb}/T{sub perpendicularb}<<1) that develops naturally in accelerators, are generalized to the case of a one-component intense charged particle beam with anisotropic temperature, including the important effects of finite transverse geometry and beam space-charge. Such instabilities may lead to an increase in the longitudinal velocity spread, which makes focusing the beam difficult, and may impose a limit on the beam luminosity and the minimum spot size achievable in focusing experiments. This paper describes recent advances in the theory and simulation of collective instabilities in intense charged particle beams caused by large temperature anisotropy. The new simulation tools that have been developed to study these instabilities are also described. Results of the investigations that identify the instability growth rates, levels of saturations, and conditions for quiescent beam propagation are also discussed.

Authors:
; ;  [1]
  1. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)
Publication Date:
OSTI Identifier:
20975084
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2436847; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; ANISOTROPY; BEAM LUMINOSITY; BEAM-PLASMA SYSTEMS; BEAMS; CHARGED PARTICLES; ELECTRON TEMPERATURE; FOCUSING; GEOMETRY; INSTABILITY GROWTH RATES; ION TEMPERATURE; PLASMA; PLASMA WAVES; SPACE CHARGE

Citation Formats

Startsev, Edward A., Davidson, Ronald C., and Qin Hong. Collective temperature anisotropy instabilities in intense charged particle beams. United States: N. p., 2007. Web. doi:10.1063/1.2436847.
Startsev, Edward A., Davidson, Ronald C., & Qin Hong. Collective temperature anisotropy instabilities in intense charged particle beams. United States. doi:10.1063/1.2436847.
Startsev, Edward A., Davidson, Ronald C., and Qin Hong. Tue . "Collective temperature anisotropy instabilities in intense charged particle beams". United States. doi:10.1063/1.2436847.
@article{osti_20975084,
title = {Collective temperature anisotropy instabilities in intense charged particle beams},
author = {Startsev, Edward A. and Davidson, Ronald C. and Qin Hong},
abstractNote = {The classical electrostatic Harris instability and the electromagnetic Weibel instability, both driven by a large temperature anisotropy (T{sub parallelb}/T{sub perpendicularb}<<1) that develops naturally in accelerators, are generalized to the case of a one-component intense charged particle beam with anisotropic temperature, including the important effects of finite transverse geometry and beam space-charge. Such instabilities may lead to an increase in the longitudinal velocity spread, which makes focusing the beam difficult, and may impose a limit on the beam luminosity and the minimum spot size achievable in focusing experiments. This paper describes recent advances in the theory and simulation of collective instabilities in intense charged particle beams caused by large temperature anisotropy. The new simulation tools that have been developed to study these instabilities are also described. Results of the investigations that identify the instability growth rates, levels of saturations, and conditions for quiescent beam propagation are also discussed.},
doi = {10.1063/1.2436847},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Collective instabilities in intense charged particle beams described self-consistently by the Vlasov-Maxwell equations are studied using a 3D multispecies nonlinear perturbative particle simulation method. The electron-proton (e-p) two-stream instability is observed in the simulations carried out with the newly-developed Beam Equilibrium Stability and Transport (BEST) code. This code provides an effective numerical tool to investigate collective instabilities, periodically-focused beam propagation in alternating-gradient focusing fields, halo formation, and other important nonlinear processes in intense beam propagation.
  • Streaming instabilities of intense charged particle beams propagating along a solenoidal magnetic field in a background plasma are studied analytically and numerically. It is shown that the growth rate of the electromagnetic Weibel instability is modified by a relatively weak solenoidal magnetic field such that {omega}{sub ce}>{beta}{sub b}{omega}{sub pe}, where {omega}{sub ce} is the electron gyrofrequency, {omega}{sub pe} is the electron plasma frequency, and {beta}{sub b} is the ion-beam velocity relative to the speed of light. Moreover, the Weibel instability is limited to very small propagation angles and long longitudinal wavelengths satisfying k{sub parallel}{sup 2}<<k{sub perpendicular}{sup 2} and c{sup 2}k{submore » parallel}{sup 2}<<{omega}{sub pb}{sup 2}{omega}{sub pi}{sup 2}/({omega}{sub pb}{sup 2}+{omega}{sub pi}{sup =} 2), where {omega}{sub pb} and {omega}{sub pi} are the plasma frequencies of the beam ions and the background plasma ions, respectively. For shorter longitudinal wavelengths, the electrostatic lower-hybrid instability becomes dominant. In this paper, the growth rates of various electrostatic beam-plasma instabilities and the electromagnetic Weibel instability are compared, and the space-time development of the modified two-stream instability is studied in detail and compared with numerical simulations.« less
  • The macroscopic warm-fluid model developed by Lund and Davidson [Phys.Plasmas 5, 3028 (1998)] is used in the smooth-focusing approximation to investigate detailed stability properties of an intense charged particle beam with pressure anisotropy, assuming small-amplitude electrostatic pertubations about a waterbag equilibrium.
  • In this paper, a 3-D nonlinear perturbative particle simulation code (BEST) [H. Qin, R.C. Davidson and W.W. Lee, Physical Review Special Topics on Accelerators and Beams 3 (2000) 084401] is used to systematically study the stability properties of intense nonneutral charged particle beams with large temperature anisotropy (T{sub {perpendicular}b} >> T{sub {parallel}b}). The most unstable modes are identified, and their eigen frequencies, radial mode structure, and nonlinear dynamics are determined for axisymmetric perturbations with {partial_derivative}/{partial_derivative}{theta} = 0.