Study of Nonlinearities and Small Particle Losses in High Power Linac
  The conception of High Power Linac developed in Russian accelerator centres is based on the use of independently phased SC resonators with quadrupole lenses between them. The type and parameters of the resonators as well as focusing structure are varied along the linac to optimise beam dynamics and the characteristics of the linac. The beam evolution in the linac was studied by simulation in 3D accelerating and focusing fields by computer code DYNAMION.   The simulation includes all nonlinearities of external fields and space charge forces. Estimations of particle losses in the beam based on analysis of the spectral properties of particle trajectories were carried out. 
A. Kolomiets, S. Yaramishev (ITEP, Moscow, Russia)