[en] Plasma Confinement times for mirror and cusp devices are investigated by using a newly developed Monte Carlo simulation model which can include the effects of binary collisions, arbitrary spatial change in the magnetic field, and external electric fields. For a mirror, the simulation results are in good agreement with theory. For a cusp (wihtout an external electric field) the confinement time is found to be proportional to the plasma radius divided by the average velocity, which is approximately the same as the theoretical confinement time given by Kaye et al. (author)