<title>Curved-Channel Microchannel Plates</title>

Abstract

The curved-channel microchannel plate (C² MCP^TM) is the latest development in high gain microchannel technology. This new electron multiplier demonstrates many significant improvements over standard microchannel plates. Standard MCPs suffer from limited gain and ion feedback. The ion feedback is produced when residual gas molecules within the channels are ionized by secondary electrons. These positively charged ions now travel back through the channel, acquiring sufficient momentum to produce secondary electrons when the ion strikes the channel wall. These secondary electrons are in turn multiplied and result in spurious output pulses. In other instances the ion may leave the channel entirely and, in the case of image tubes, impinge upon the photocathode causing ion poisoning which eventually degrades the quantum efficiency of the cathode. In order to operate a microchannel plate in the high gain analog mode or photon counting mode, it becomes necessary to limit ion feedback. In the C2 MCP this is accomplished by curving the channels to a sufficient radius to reduce the distance an ion can travel prior to striking the channel wall, thus restricting its momentum and probability of producing secondaries which cause spurious pulses, which in turn degrade the noise figure. By substantially reducing the rate of ion feedback, it now becomes possible to operate a single MCP at gains in excess of 106, and since the C' MCP is a single piece electron multiplier, the spatial resolution of the electron image is maintained. The C² MCP offers low noise uniform gain with either analog or pulse saturation outputs. The C² MCP can be custom fabricated per customer dimensions.