Analytical and nonlinear perturbative simulation studies of the equilibrium and stability properties of intense charged particle beams for heavy ion fusion

This paper presents an overview of recent analytical and numerical investigations of collective processes in intense ion beams at the Plasma Physics Laboratory based on the nonlinear Vlasov–Maxwell equations. The topics covered include: (a) nonlinear stability theorem for quiescent beam propagation at high space-charge intensities; (b) development and application of Hamiltonian averaging techniques for intense beam propagation through alternating-gradient field configurations; (c) kinetic studies of the electron–ion two-stream instability which occurs when an (unwanted) component of electrons is present in the beam transport line; (d) application of the newly developed three-dimensional, multispecies, nonlinear perturbative particle simulation scheme, called the Beam Equilibrium, Stability and Transport (BEST) code, to investigate the linear and nonlinear dynamics of intense beam propagation, including the electron–ion two-stream instability; and (e) investigations of the role of collective mode excitations in the expulsion of particles from the beam core and the production of halo particles. Finally, the linear growth properties of instabilities driven by pressure anisotropy are investigated within the framework of a macroscopic warm-fluid model.