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One of the main reasons for the space vehicles (SV) power supply systems failure is a secondary arc. In the statistics of fatal failures that can lead to the SV loss, the failure rate of the power supply systems is 9%, but despite this, there are no standard methods for diagnosing the on-board equipment for the arc stability, due to the relative novelty of the problem. The problem we encountered is associated with the need to switch power supply systems to the voltage levels that are much higher than the arc voltage in the space vacuum. From the point of view of the defects downing that can lead to arcing, the most vulnerable are the insulation coatings. Therefore, a significant part of the problem solution is concentrated in the development of the specific methods for these coatings diagnostics. In space technology, such diagnostics significance is increased due to the inability to provide necessary repairs or services in the outer space.

This paper reports on the study of physical processes in a high-current vacuum arc shunted by semiconductor elements. The switching dynamics between a vacuum circuit breaker (VCB) and an assembly of several semiconductor elements connected in parallel to the VCB is investigated. The breaking capacity of a VCB-thyristor system is analyzed. It is found that at the instant of current switching, the arc can operate at a rather low voltage of 8–10 V. It is shown that there exists a certain limiting mode close to the conditions for current switching. In this mode, at least two cathode spots are observed. [ABSTRACT FROM PUBLISHER]