Propagation of short electron pulses in underdense plasmas
- Department of Physics, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90024 (United States)
Dense relativistic electron beams traversing a plasma, in what is known as the underdense, or ion focusing, regime experience a strong, linear transverse restoring force. This force arises from the nearly immobile ions which form a channel of uncompensated positive charge when the plasma electrons are ejected in response to the introduction of the beam charge. This phenomenon can be used for focusing the electron beam to very high densities over long propagation distances. Several schemes have been proposed, including the nonlinear plasma wake-field accelerator, the adiabatic plasma lens, and the ion-channel laser, whose viability is based on this focusing effect for very short pulse, high current electron beams propagating in plasma. In this paper we examine, analytically and numerically, the self-consistent requirements on plasma density, beam current, length, and transverse emittance which must be satisfied in order for ion-channel formation and near equilibrium beam propagation to exist over the majority of the length of the electron beam. The dynamics of the beam-plasma system are modeled by a simultaneous solution of the plasma electron cold-fluid equations, and the Maxwell-Vlasov equation governing the beam's thermal equilibrium. The effects of introducing a strong axial magnetic field on the plasma response and beam equilibria are examined. In addition to developing criteria for self-consistent equilibrium focusing, a time-dependent analysis where the beam particles are treated as mobile particles in cells is developed in order to study the dynamical approach of this equilibrium. Inherently time-dependent phenomena, such as matching of the beam into the plasma and adiabatic lenses, are then examined with this method.
- DOE Contract Number:
- FG03-93ER40796; FG03-92ER40693
- OSTI ID:
- 7069558
- Journal Information:
- Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States), Vol. 49:5; ISSN 1063-651X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
Ta
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM-PLASMA SYSTEMS
ELECTRON BEAMS
WAVE PROPAGATION
BEAM OPTICS
EQUILIBRIUM
PULSES
RELATIVISTIC RANGE
TIME DEPENDENCE
BEAMS
ENERGY RANGE
LEPTON BEAMS
PARTICLE BEAMS
661220* - Particle Beam Production & Handling
Targets- (1992-)
700390 - Other Plasma Physics Studies- (1992-)