Low-resistance conductively cooled microchannel plates

摘要

Reducing plate resistance is one of the possible ways to increase the count rate capability of microchannel plates (MCPs). Bonding a low-resistance plate to a cooled substrate provides a conductive path for heat transport an prevents thermal runaway. MCPs of very low resistance (less than or equal to 500 k approximately ega@), bonded to a Peltier cooler, were tested using different bonding techniques. Stable, reproducible operation of a rear-cooled MCP (60:1, 10 micrometer channels) was achieved for biases up to 1320 volts (R$-MCP$/ equals 260 k approximately ega at that voltage), when the MCP bias current was as high as 5.1 mA and the heat generated by the plate was 0.78 W cm$+$MIN@2$/. The count rate reached the value of 10$+8$/ cm$+$MIN@2$/s$+$MIN@1$/ limited not by the plate recharge time, but by the intensity of the mercury vapor UV lamp (2540 angstrom) used for illumination. The dark noise, at the same time, was less than 1 cm$+$MIN@2$/s$+$MIN@1$/. A thermal model of such conductively cooled MCPs is described. The count rate characteristic of a microchannel plate is well-known to depend on the pattern of illumination. This paper updates our previous investigation of radial gain depression in the vicinity of high count rate point-like illumination.