强流电子束二极管等离子体光学诊断

Optical diagnosis system for intense electron beam diode plasma

通过处理强流电子束加速器主开关导通之后所形成的高压电脉冲,得到了二极管等离子体光学诊断的同步时间基准。采用高压电脉冲延时结合二极管等离子体光信号延时的方案,实现了相机曝光过程与等离子体发光过程的ns级精度同步。综合采取屏蔽、滤波等措施,实现了整个系统的电磁兼容,最终稳定地拍摄到了ns时间分辨的二极管等离子体发光过程。

A nanosecond time-resolved imaging platform for diode plasmas diagnostics has been constructed based on the pulsed electron beam accelerator and high speed framing camera（HSFC）.The accelerator can provide an electrical pulse with voltages of 200-500 kV,rise-time（from 10% to 90% amplitude） of 25 ns and duration of 110 ns.The diode currents up to kA level can be extracted.The trigger signal for camera was picked up by a water-resistor voltage divider after the main switch of the accelerator,which could avoid the disadvantageous influence of the time jitter caused by the breakdown of the gas gaps.Then the sampled negative electrical pulse was converted into a transistor-transistor logic（TTL） signal（5 V） with rise time of about 1.5 ns and time jitter less than 1 ns via a processor.And this signal was taken as the synchronization time base.According to the working characteristics of the camera,the synchronization scheme relying mainly on electrical pulse delay method supplemented by light signal delay method was determined to make sure that the camera can work synchronously with the light production and transportation from the diode plasmas within the time scale of nanosecond.Moreover,shielding and filtering methods were used to restrain the interference on the measurement system from the accelerator.Finally,time resolved 2-D framing images of the diode plasmas were acquired.