强流相对论多注电子束研究进展

研制了基于爆炸发射的扇形和圆柱形多注阴极系统，并开展了强流相对论多注电子束的实验研究。研究发现:扇形多注阴极由于发射端面电场分布严重不均，电子束主要由尖端发射，束斑畸变明显，当每注扇形电子束进入到多注扇形漂移管内时，在空间电磁场的作用下电子束会绕束心旋转，导致束斑的畸变和束流的损失；圆柱形多注阴极发射端电场分布相对均匀，电子束斑畸变较小，每注电子束在多注漂移管内绕束心的旋转不会引起束斑的畸变和束流的损失；由于阴极杆和多注阴极柱的发射，多注电子束品质较差，进入多注漂移管时存在电子束轰击管壁现象，造成束流的损失甚至截止。采用大内径磁场可增大阳极筒内半径，明显提高束流的传输效率。目前，采用功率约6.5 GW、传输效率约89%的相对论多注电子束驱动的多注速调管，可实现GW量级的微波输出。

Development progress of relativistic multi-beam

This paper introduces the studies on the relativistic multi-beam electron gun with different structures. The theoretic analysis and experimental results show that the spot distortion is obvious with fan-shaped multi-beam cathode due to the nonuniformity of the surface electric field. Furthermore, the fan-shaped beam rotation around the beam center, caused by the effect of space electromagnetic field, exasperates the beam distortion and reduces the transmission efficiency evidently. Whereas, the electric field on the surface of cylindrical multi-beam cathode is more uniform, which restrains the spot distortion. Meanwhile, the self-center rotation can not change the beam profile with the columned form. Considering the emission from the multi-cathode rods and cathode base, the transmission efficiency of the multi-beam is limited. In addition, the strong beam impaction on the multi-beam waveguide could lead to intense current transport cutoff. It is effective to increase the transmission efficiency by enlarging the inner radius of magnetic system. At present, the output power of multi-beam klystron can get to the order of gigawatt with multi-beam power 6.5 GW and transmission efficiency 89%.