On transverse stability in an electron ring accelerator

Suppression of coherent transverse instabilities is a basic requirement for stable operation of an electron ring accelerator experiment. Landau damping of the unstable radial electron-ion modes and the resistive wall modes may be insufficient after final compression of the ring owing to the curvature and image effects. A specific choice of image focussing and ion loading is then required in order to avoid a large reduction of ring quality. The theoretical implications of this situation, which affects the stable working range of a heavy ion electron ring accelerator, are studied for parameters relevant to the Garching “Pustarex” experiment.