Effect of screen-electrode structures on MCP imager vacuum-gap discharge

The vacuum-gap discharge damage of micro-channel plate(MCP) imagers based on two screen-electrode structures, with Al-screen and indium-tin-oxide(ITO) screen respectively, is investigated after first arcing. The results show that the erosion pattern of Al-screen MCP imager appears as crater, and the electric insulating strength is less than 3 kV/mm under 10 μs-wide screen voltage, independent of MCP. The erosion of ITO-screen mostly appears as phosphor transporting to MCP, which drives field emission to steady state, and the electric insulating strength can reach 9 kV/mm at 10 μs-wide voltage. Thus, the discharge of MCP imagers depends mostly on screen-electrode structure, and ITO-screen MCP imagers can obtain higher electric insulating strength.