无增益微通道板选通X射线皮秒分幅技术的研究

传统的X射线分幅相机的时间分辨率已达35 ps，由于微通道板（microchannel plate, MCP）中电子的渡越时间弥散较大，限制了分幅相机时间分辨率的进一步提高，因此，要提高时间分辨率，就必须减小电子的渡越时间弥散。申请者首次提出采用无增益MCP代替有增益MCP来制作分幅相机。理论分析表明，当MCP两端面间的电压为1 kV时，无增益MCP中电子的渡越时间弥散为3.9 ps，而有增益MCP中电子的渡越时间弥散为42.3 ps，因而采用无增益MCP来研制X射线分幅相机能够获得较好的时间分辨率。无增益MCP选通X射线分幅相机由针孔阵列、无增益MCP变像管、选通脉冲发生器及CCD构成。本项目将对无增益MCP变像管和选通脉冲发生器进行研究。无增益MCP变像管采用近贴聚焦方式，由阻抗渐变线、微带阴极、无增益MCP和荧光屏组成。选通脉冲发生器由雪崩三极管线路和雪崩二极管脉冲成形电路组成。

The temporal resolution of the traditional x-ray framing camera is short to be 35 ps. The temporal resolution is limited by the electron transit time spread (TTS) in the microchannel plate (MCP). In order to improve the temporal resolution, the TTS must be reduced. A new method is presented in the first, which is using a non-gain MCP instead of the gain MCP to develop the framing camera. The theoretical results show that the transit time spreads are 3.9 ps and 42.3 ps in the non-gain and gain MCP respectively, while the MCP is applied with 1 kV direct current voltage. The preferable temporal resolution of the x-ray framing camera will be obtained by using the non-gain MCP. The non-gain MCP gated x-ray framing camera is made up of four basic components, the pinhole array, the non-gain MCP imager, the gating pulse generator, and the CCD camera system. The non-gain MCP imager and the gating pulse genetator will be researched in this project. The proximity focused non-gain MCP imager is consisted of tapered transmission line, microstrip line cathode, non-gain MCP and phosphor screen. The gating pulse genetator is consisted of avalanche transistor circuit and avalanche diode pulse-forming circuit.