A digital computer program for the simulation of positive or negative particle beams on a PC

PBGUNS, an expanded and improved version of the SNOW2D code for extracted ion beams will be described and demonstrated. The new code includes the electrode description and electron beam capabilities of the SPEED code. The new version includes positive and negative ion beam extraction systems and may include skew¹ (azimuthal energy particles) permitting the simulation of thermal effects in high energy plasmas, thermal effects in low energy electron beams, and the computation of x-x´ emittance plots from axisymmetric simulations. Plasma electrons (and positive ions for negative ion beams) are simulated with background Boltzmann distributions. Electrodes are described with quadratic equations while potentials are solved by basic relaxation techniques on a rectangular array of squares. Smooth electrodes are created by extending fields into electrodes. A fine mesh covers the cathode and/or plasma-extraction region to furnish the additional accuracy required for the calculations near the particle emission surface. Axisymmetric and rectangular magnetic fields can be included in the trajectory calculations. It is written in FORTRAN 77, employing Calcomp-Versatec type plotting routines and is run on 386 or 486 IBM PC´s with DOS Extenders. Generic FORTRAN 77 is used to facilitate the transfer of the program to other computers with only minor modifications