多脉冲电子束发射度测量

采用多孔板并结合电子束在石英片相互作用产生的契仑柯夫辐射，对以天鹅绒为阴极发射的强流多脉冲电子束发射度和亮度进行了实验研究和测量。实验观测到了有外加磁场条件下的电子束发生旋转现象。对于电子能量为600 kV左右的电子束，多孔板处的磁场小于2.7 mT时，电子束元的偏离已经小于2°。分别测量了天鹅绒阴极发射的强流四脉冲电子束和双脉冲电子束的积分亮度,分别为7.5×107 A/(m·rad)2和4.14×108 A/(m·rad)2。结果表明，双脉冲电子束的积分亮度明显优于四脉冲电子束的积分亮度，进而验证了阴极等离子体对多脉冲电子束亮度具有重要影响，降低了电子束的品质。

Measurement of multi-pulsed electron beams emittance

The emittance of multi-pulsed electron beams was experimentally measured using pepper pot and thus the corresponding brightness was calculated. Different from using fluorescent screen as the recorder of beam divergence angle, a quartz foil was used to record the information through Cerenkov radiation, which is generated by the interaction of electron beamlets and the quartz foil. The phenomenon of beam rotation in magnetic field was observed in the experiment, and the integrated brightness of double-pulsed and four-pulsed beams were measured. For the electron beam of about 600 kV, the divergence of beamlets was below 2° when the magnetic field at the pepper plate was lower than 2.7 mT. The calculated brightnesses of the double-pulsed and four-pulsed beams were 4.14×108 A/(m·rad)2 and 7.