Chen Hongfei

Leakage Current of Grounded Dielectrics in Electron Radiation as a Diagnostic Method to Evaluate the Deep Charging Hazards in Space

Deep dielectric charging, which is a coupling process of charge deposition and charge relief, is a significant factor in spacecraft anomalies and failures. With the aim of developing a method for evaluating the deep dielectric charging hazards, this study investigated the leakage current and charging electric field of grounded dielectrics in space usage by a method combining Monte Carlo simulation and a model of radiation-induced conductivity. The analysis adopts multiple cases of electron spectra and various thicknesses of the shielding layer and dielectric. The analysis results show that the leakage current, which can be easily measured, is strongly related to the charging electric field in various situations. Therefore, monitoring the leakage current can be a more effective approach for evaluating deep dielectric charging hazards than monitoring electron flux.

Thermal experiment of silicon PIN detector

The experiment of this paper is the thermal test of the leakage current of silicon PIN detector. Raising temperature may cause the detector to increase leakage current, decrease depletion and increase noise. Three samples are used in the experiment. One (called ΔE) is the sample of 100 μm in thickness. The other two (called E1 and E2) are stacks of five detectors of 1000 μm in thickness. All of them are 12 mm in diameter. The experiment has been done for 21 hours and with power on continuously. The samples have undergone more than 60°C for about one hour. They are not degenerated when back to the room temperature. The depletion rate is temperature and bias voltage related. With the circuit of the experiment and temperature at 35°C, ΔE is still depleted while E1 and E2 are 94.9% and 99.7% depleted respectively. The noises of the samples can be derived from the values at room temperature and the thermal dependence of the leakage currents. With the addition of the noise of the pre-amplifier, the noises of E1, E2 and ΔE at 24°C are 16.4, 16.3, and 10.5 keV (FWHM) respectively while at 35°C are about 33.6, 33.1, and 20.6 keV (FWHM) respectively.