附加电极对扫描变像管性能的优化

Optimization effect of auxiliary electrode on streak image tube

通过分析影响变像管性能的主要因素,以提高其时间分辨率、空间分辨率和动态范围为优化思路,确定了在扫描变像管中荧光屏邻近区域引入等径螺旋电极以产生纵向均匀加速场的优化方案。分析得知,该优化结构可以在几方面改善变像管的性能:增加粒子到达荧光屏的纵向速度、减小粒子通过偏转板与荧光屏之间区域的渡越时间和渡越时间弥散、提高荧光屏的亮度。在横向约束带电粒子束的发散,通过减小空间电荷像差而改善电子光学系统的空间分辨率。另外,附加电极的引入也为降低加速阳极电位和偏转电极电位从而提高偏转系统的灵敏度提供了一定的空间。

By getting insight into the main affecting factors on the property of streak image tube and keeping the designing orientation on the improvement of such three performance parameters as temporal resolution, spatial resolution and dynamic range, an optimized scheme is achieved with introduction of an auxiliary accelerating electrode in the neighborhood of fluorescent screen. It is an equal-diameter spiral dielectric electrode, which can bring about a uniform axial accelerating field. Correspording discussion indicates that the electrode can optimize the performance of streak image tube in the following aspects： increasing the screen-intersected velocity of electrons and hence the screen brightness, decreasing the transition time span and relevant dispersion between the deflection plates and the screen, lessening the traverse spread and space charge aberration of electron beam and eventually improving the spatial resolution of the whole electron-optical system. And also, the possibility of lowering the potentials of accelerating anode and deflecting plate is largely enhanced by the modification to the optical system.