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Since the electronic power conditioner (EPC) is a crucial part of a space traveling-wave tube amplifier (STWTA), its reliability issue must be considered. The most effective way to prevent insulation breakdown is potting. Silicone elastomers are commonly used as an encapsulant for the EPC because of their good physical and electrical properties. The properties of the encapsulant and the interfaces change under the influence of γ-radiation, which may result in the failure of the potted modules. In this work, a comprehensive evaluation methodology is proposed for silicone-based potted modules, where besides physical and electrical properties, the effect of γ-radiation on the encapsulated interface is also considered. The results show that with the increase of the irradiation dose, the crosslinking density, hardness, elastic modulus, volume resistivity, dielectric constant, and storage modulus are increased by 301.6%, 76.3%, 289.7%, 396.1%, 5.0%, and 589.8%, respectively. In contrast, the elongation at break and dielectric loss factor are decreased by 83.8% and 57.8%. In addition, the tensile strength and breakdown strength first increase and then decrease, while the coefficient of thermal expansion of the interface shows the opposite trend. Since the interface bonding state does not change and the electric field strength of the tip decreases slightly with an increasing dielectric constant, the average value of the partial discharge inception voltage increased slightly. Full article

Since the electronic power conditioner (EPC) is a crucial part applied of a Space Travelling-wave Tube Amplifier (STWTA), the reliability issue must be considered. Of all the failure modes of an EPC, the insulation failure of an EPC in thermal and moist environments is the most serious, and needs special attention. By investigating the influence of contamination, humidity, and temperature on surface insulation resistance (SIR) and surface discharge, we focused on the determination of the insulation failure boundary in an EPC. Considering real working conditions, we used the typical circuit applied in the EPC as the test object. The insulation deterioration phenomenon under different thermal and moisture stress was studied. The results show that: (1) SIR of the samples did not change with contamination levels when the relative humidity (RH) was below 70%. When RH was higher than 75%, the SIR began to vary with temperature and ionic contaminant concentration. (2) Even if the samples were not contaminated (the ionic contamination concentration was less than 1.56 μg/cm²), the deterioration of the SIR still occurred at 85 °C/90% RH. (3) The insulation failure boundary caused by surface discharge, and the degree of electrical erosion were related to humidity, pollution, voltage and temperature. To improve the failure caused by insulation, encapsulation was used. Experiments showed that encapsulation is an effective protection method to prevent insulation deterioration. Full article