Revealing pre-breakdown processes of a single-gap pseudospark switch triggered from the anode side

Abstract

Pseudospark switch is a special kind of low-pressure (typically 1–100 Pa) high-voltage pulsed discharge switch with the hollow electrode configuration. This paper experimentally investigates the pre-breakdown processes of a single-gap pseudospark switch triggered from the anode side. The species and contents of impurities on copper electrode surface are firstly analyzed, which mainly include C, N and O. Then, at the same conditions, the trigger delay and jitter of triggering from the anode side are significantly higher than the cathode side, as well as the minimum voltage and pressure that the switch can be triggered. The evolution of the discharge region of the pseudospark switch triggered from the anode side is observed by the ICCD camera for the first time in the literature. The time-resolved images show that the luminescence firstly appears in the hollow anode where the trigger discharge happens and then in the hollow cathode, the cathode hole, the main gap and the anode hole successively, which is completely different from triggering from the cathode side. Finally, a model considering the migration and collisions of ions and fast atoms is established, and it points out that the ion flux from the hollow anode plays an important role in triggering from the anode side. The key processes also include the formations of the positive space charge column inside the hollow cathode and the intense secondary electron emission as an electron source for the main gap.