A theoretical investigation of two-stream instability in two hollow relativistic electron beam

Summary form only given. The two-stream klystron has been proposed to enhance the current modulation, thereby improving the performance of relativistic klystron amplifiers. In the two-stream klystron amplifier, two hollow electron beams propagate in the downstream region. A charge bunching of one beam compensates for that of the other beam, considerably reducing the influence of the self-electric field arising from this bunching. In addition, the self-growing mechanism of the charge bunching due to the two-stream instability of the two beams enhances further current modulation. The two-stream klystron is subjected to various physical phenomena, including the influence of the axial momentum spread on the longitudinal two-stream instability and effects of the transverse two-stream instability on beam propagation.