Experimental investigation of total electron emission yield of polyimide film under various temperatures

As the thermal variation may change the total electron emission yield (TEEY) of materials and may ultimately result in unexpected surface charging, it is necessary to study the TEEY at various temperatures. In this research, we first updated the TEEY measurement system with a newly designed sample stage for different temperatures (−50, 25, and 100 °C) and the primary electron from 25 eV to 10 keV. By using the 30 μs/20 nA primary electron beam and sample scanning method to mitigate surface charging, the TEEY could be accurately obtained for dielectrics. Then, we chose a kind of polyimide film (Kapton 100H) used on spacecraft and a gold film sample to compare the TEEY at various temperatures. The results show that high temperature leads to higher TEEY of Kapton films, whereas 25 and −50 °C also leads to the same. On the other hand, the TEEY of gold remains the same at different temperatures. In the view of surface hole density and charge transportation, the TEEY variation of Kapton films was analyzed by bulk conduction, charge mobility, and the electron–hole recombination property. It is considered that the dissipation rate of holes is sensitive to temperature, and furthermore, the TEEY of Kapton films is dependent on temperature.