Penetration of intense charged particle beams in the outer layers of precompressed thermonuclear fuels

Abstract

This paper emphasizes the energy dissipation through collective electromagnetic modes (mostly transverse to the incoming beam) of ultraintense relativistic electrons and nonrelativistic protons interacting with a supercompressed core of deuterium + tritium (DT) thermonuclear fuel. This pattern of beam–plasma interaction documents the fast ignition scenario for inertial confinement fusion.The electronmagnetic Weibel instability is considered analytically in a linear approximation. Relevant growth rates parameters then highlight density ratios between target and particle beams, as well as transverse temperatures. Significant refinements include mode–mode couplings and collisions with target electrons. The former qualify the so-called quasi-linear (weakly turbulent) approach. Usually, it produces significantly lower growth rates than the linear ones. Collisions enhance them slightly for kc /ωp < 1, and dampen them strongly for kc /ωp ≥ 1. Those results simplify rather drastically for the laser-produced and nonrelativistic proton beams. In this case, those growth rates remain always negative through a wide range of beam–target parameters.