Thermal characterization of resistance and gain of microchannel plate (MCP) detectors for the JENI experiment

摘要

The microchannel plate (MCP) has been used for decades as a photon, electron and atoms detector in most of the space instruments dedicated for X-rays, energetic neutral atoms and charged particle imaging. The deep-space missions, as near-future ESA Jupiter Icy moon Explorer (JUICE) mission, expect very low temperature conditions on the destination orbit. Since instruments are usually calibrated on the ground under the “room” temperature, it is very important to know the variation of the detectors’ properties with temperature. The resistance and the gain of MCP detectors, dedicated for the Jovian Energetic Neutrals and Ions (JENI) sensor as part of the Particle Environment Package (PEP) instrument onboard JUICE, were measured as a function of temperature at INTRASPEC TECHNOLOGIES, Toulouse, France over the temperature range of ? 50 to + 50 °C and at the CALIPSO-3 facility of the Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France over the temperature range of ? 25 to + 25 °C using samples from PHOTONIS France and PHOTONIS USA. Depending on how the resistance of an MCP detector behaves with temperature, it is possible to properly size a high voltage source or, conversely, to choose a glass technology according to the resistance range required for the MCP detector or their minimum operational bias strip current in relation to the extracted current due to the particle counts. Moreover, since the environment of Jupiter is very severe, the sensors of the PEP package instrument onboard JUICE will operate in the presence of high-energy particles which represent a noise source for them despite the shielding of the instrument against radiation. In particular, the background radiation in the Jovian environment represents a crucial issue for the JENI MCP detectors whose gain can be degraded prematurely if too much of charge is extracted from them. Our measurements show that the gain variation of JENI MCP detectors depends on their characteristi