Landau damping effect due to the trapped ions in a compact electron storage ring

Theoretical analysis and experimental results show that the Landau damping due to trapped ions is greatly enhanced in the low-energy beams in compact electron storage rings. This enhancement originates mainly from the decrease in beam size in the low-energy region. This effect must indeed be the main reason why the recently developed compact rings can store a large current even though they have a low injection energy. In the typical energy region of compact rings, more positive utilization of this effect could make the damping rate of a lower-energy beam far larger than that of a higher-energy one. Therefore, if we could control the effect of the trapped ions, we might prefer to adopt lower energy in order to inject a large current in a compact ring. (orig.)