Microchannel plate gain uniformity of gated framing imaging

摘要: In an X-ray framing camera, the gating pulse will be attenuated as it transmits along the microchannel plate (MCP) microstrip cathode, which affects the dynamic gain uniformity of the MCP. An attenuation model for gating pulse transmitting on MCP microstrip cathode is established, and the dynamic gain uniformity of the microstrip cathode with a length of 40 mm and a width of 8 mm are simulated. To enhance the computational efficiency, a method has been presented to replace the 10^7 MCP channel holes with the material loss angle. The simulation shows that while a microstrip cathode is driven by a gating pulse with an amplitude of -2 kV and a full width at half maximum (FWHM) of 200 ps, the pulse amplitude reduced to -1.78 kV and the FWHM increased to 240 ps for a 40 mm transmission distance. As a result, the MCP gain is decreased to 33% along the pulse transmission direction. An X-ray framing camera has been developed to verify the correctness of the theoretical model. The MCP dynamic gain uniformity is measured using an ultraviolet laser with a FWHM of 6.5 ns, which demonstrates that the gain drops to 27% consistent with the simulation result.