在注入器段阳极杆内不同位置进行电子束包络的测量可以为多脉冲电子束在注入器段的传输磁场配置调试提供最直接的支撑,也是研究热阴极发射性能的重要手段,测量工作具有极为重要的意义。神龙二号采用热阴极作为多脉冲电子束源的发射体,对真空的要求极高,且加热及降温周期较长,不适合频繁地破坏真空进行测量位置的调整; 针对这样的特点,设计了一套可伸缩式的测量装置,结合多幅分幅相机,在不破坏真空的情况下,可以完成多个位置的束包络的时间分辨测量,在提高测量效率的基础上进一步提高了注入器的调试效率。

The measurement of electron beam envelope at different position in the anode pipe of injector with a large area thermionic cathode for a linear induction accelerator is very important. It can help to know the emission characteristic of the thermionic cathode for multi pulsed beam and to debug a matched magnetic field for the electron beam transmission in the anode pipe. Dragon-Ⅱ injector adopts a large area thermionic cathode. The period time for heating up or cooling down is very long and the demand of vacuum in the injector is very high especially during operation. It is a problem to destroy the vacuum frequently in order to measure the electron beam envelope in the injector with some ready-made measurement. A multi pulsed electron beam envelope measurement system mainly consists of an extendible and retractile sleeve and a high speed multi framing camera and an optical transition radiation target has been developed to achieve the measurement in the injector without destroying the vacuum. This system can measure envelope at different position in the whole range of the anode pipe and obtain some time-resolved results. This measurement ability has improved greatly the debugging efficiency of Dragon-Ⅱ injector.