Recent progress in the simulation of heavy ion beams

Production of electric power by using a beam of heavy ions to ignite an ine rtially-confined fusion target requires the focusing of high-power beams on to a small spot several meters distant from the final lens system. Beams wi th the necessary intensity generally behave like warm nonneutral bounded pl asmas where beam kinetic temperatures are sufficiently high that a cold-pla sma description can be inadequate for describing the collective space-charg e modes. In view of the complexity of the self-consistent nonlinear dynamic s, analytic study has largely been limited to the singular Kapchinskij-Vlad imirskij (K-V) distribution. Numerical simulations, primarily using the WAR P [D. P. Grote, A. Friedman, I. Haber, W. Fawley, and J. L. Vay, Nucl. Inst rum. Methods Phys. Res. A 415, 428 (1998)] particle-in-cell (PIC)/accelerat or code, have been employed to identify the degree to which the analytic re sults, especially the predictions of unstable modes, are applicable to real istic beam distributions. During extensive benchmarking of the code against experiments at Lawrence Berkeley National Laboratory, Lawrence Livermore N ational Laboratory, and the University of Maryland, a particular feature of the beam which has been seen in both experiment and simulation is the laun ching, in the source region, of collective warm-plasma oscillations similar to those predicted on the basis of the K-V analysis. (C) 1999 American Ins titute of Physics. [S1070-664X(99)96605-3].