micro-channel plate, MCP

A "micro-channel plate (MCP)" is a circular glass plate with a thickness of ～0.5 mm and a diameter of ～10 mm, in which cylindrical electron multipliers with an inner diameter of ～10 μm are arrayed in a honeycomb structure. The front-side surface and the backside surface of the MCP are coated with a metal. The former side acts as the input electrode (cathode) and the latter as the output electrode (anode). When a voltage is applied between the two electrodes, electrons that enter the cathode strike the inner walls of the MCP, emitting multiple secondary electrons. These emitted secondary electrons are accelerated by an electric field in the channels and repeat collision with the (totter) inner walls of the MCP. Finally, the electron flow is received at the anode as an amplified electric signal. Since the MCP has high sensitivity for not only electrons but also ions and X-rays, this plate is used as a detection element for these signals. In a TEM, the MCP is used for a backscattered electron detector attached to the TEM column.

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