Survey of collective instabilities and beam–plasma interactions in intense heavy ion beams

Abstract

This paper presents a survey of the present theoretical understanding based on advanced analytical and numerical studies of collective processes and beam-plasma interactions in intense heavy ion beams for applications to ion-beam-driven high energy density physics and heavy ion fusion. The topics include: discussion of the conditions for quiescent beam propagation over long distances; and the electrostatic Harris instability and the transverse electromagnetic Weibel instability in highly anisotropic, intense one-component ion beams. In the longitudinal drift compression and transverse compression regions, collective processes associated with the interaction of the intense ion beam with a charge-neutralizing background plasma are described, including the electrostatic electron-ion two-stream instability, the multispecies electromagnetic Weibel instability, and collective excitations in the presence of a solenoidal magnetic field. The effects of a velocity tilt on reducing two-stream instability growth rates are also discussed.Operating regimes are identified where the possible deleterious effects of collective processes on beam quality are minimized.

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

“…It is important to note that apart from the heating produced inside the plasma source, significant additional electron heating may be provided by the ion beam pulse as a result of collective (beam-plasma) streaming instabilities. [26][27][28] Assuming, for simplicity, a scalar form of the electron pressure, p e ¼ n e T e , the radial component of the electron force balance equation [Eq. (3)] is given in the linear approximation, n b ( n e , by…”

Effects of beam-plasma instabilities on neutralized propagation of intense ion beams in background plasma

“…The streaming of the ion beam relative to the background plasma can cause the development of fast electrostatic collective instabilities [3]. These instabilities produces fluctuating electrostatic fields that cause a significant drag on the background plasma electrons and can accelerate electrons up to the average ion beam velocity.…”

Nonlinear effects of beam-plasma instabilities on neutralized propagation of intense ion beams in background plasma

“…For a thin, infinitely massive ion beam with r b p the beam current density is only partially neutralized, so that the remaining current density produces an azimuthal self-magnetic field that pinches the beam [1]. On the other hand the streaming of the moderately heavy ions relative to the background plasma can cause the development of fast electrostatic collective instabilities between beam ions and background electrons [2]. As demonstrated numerically in this paper using the particle-in-cell code LSP [3], the nonlinear stage of these instabilities produces fluctuating electrostatic fields which cause a significant drag on the background plasma electrons and result in producing local current densities which may significantly exceed the beam current density [4].…”