Physics guide of BETACOOL code (V.1.1)

Le résumé fourni par la source

Initially, BETACOOL code was developed as a program for simulation of particle dynamics in ion storage rings under the action of electron cooling force. Further development led to addition of other effects and numerical algorithms for tracking. First algorithm of numerical tracking is RMS Dynamics which calculates evolution in time of the r.m.s. (root mean square) parameters of the ion beam distribution function and particle number. RMS Dynamics algorithm is based on solution of equation for the second order moments of the distribution function. Characteristic times of the evolution of the beam parameters for a few general effects are calculated under assumption of Gaussian shape of the distribution function. Second algorithm of tracking is Model Beam approach. It was developed on the basis of SIMCOOL code which was originally written by BINP group at Novosibirsk. This algorithm uses a few thousands of test particles with an arbitrary distribution. The action from IBS on each of the test particles is calculated from the instantaneous distribution of the test particles. This algorithm has a good accuracy when the distribution of test particles is close to Gaussian. Some modification of this method was made for simulation of IBS in the case of non Gaussian distribution. Evolution of the ion distribution function is described by the Fokker-Plank equation. In general case, the friction and diffusion terms depend on the distribution function. However, in some cases when the effects acting on the distribution function do not lead to change of its shape, the Fokker-Plank equation can be reduced to equation for the second order moments of the distribution function.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.