Micro-channel plate (MCP) detectors are microscopic holes in a plate. They get put in an electric field and there act like many tiny dynodes, amplifying any electrons that enter. This makes them useful, amongst other things, in sensors that need snappy reaction times and spatial resolution. They get manufactured for instance by etching out the 'soft' center part of fibre optics-bundles or stretching bundles of glass tubes. I read in several documents relating to MCP that their performance degrades with use, and wikipedia states that 'MCPs have a fixed charge that they can amplify in their life'. On the other hand, i saw that they get a 'electron scrubbing' treatment (they get put in a big electric field and basically worked out) that is supposed to bring their amplification down to a sustained level, and MCPs are even used as electron sources in xray sources and there supposedly last longer than the usual filaments.
- how is the fixed life-time charge justified, what happens?
- is there different breeds of MCP some of which are not beholden to the lifetime charge, and if so how does that work?
UPDATE: It seems that many papers conflate MCPs with MCP-Photocathode Detectors, and some, 'damage'/'reduced efficiency'-references may actually refer to the Photocathode, not the MCP itself. Also, the 'lifetime-charge' may actually refer to a synthetic definition of 'lifetime' that only counts quantum efficiencies (QE) between 100% and x% (80?)of initial value as 'life' (analogous to some LED 'lifetime' definitions) - thus the MCP-PC QE levelling out at 70% would not be counted as infinite life. - Some MCP 'scrubbing' apparatus' actually use another MCP as electron source...
Can somebody confirm?