Discharge ignition in the micro-cathode arc thruster

Abstract

The breakdown mechanism in the Micro-Cathode Arc Thruster has been studied to better understand the nature of the discharge ignition and to extend the ignition system lifetime. It has been found that optimal material selection of the insulator is an important factor during breakdown. Two opposite processes have been found to cycle during operation. The processes are degradation of the conductive film from the inter-electrode interface and re-deposition of the conductive film due to cathode spot erosion. Initial resistances were found to vary from hundreds of ohms to thousands of ohms based on the initial connectivity of the film to the electrodes. After initial breakdown however, resistances have been found to stabilize in a typical pattern. Materials capable of withstanding high temperatures, high pressures, and smooth surfaces are shown to be beneficial for extending thruster lifetime.

Low energy surface flashover for initiation of electric propulsion devices

“…Use of the fuse wire explosion for the discharge ignition is highly unreliable if multiple ignitions are expected [27]. The triggerless approach suffers from electrode/film assembly damage after relatively low number of triggering events 1,000 -10,000 [29].…”

Theory of electric field breakdown nucleation due to mobile dislocations

“…This critical process leads to plasma formation between electrodes in vacuum, and to subsequent arcing of current between the electrodes, serving as a major failure mechanism in numerous applications. [17][18][19][20] Specifically, arcing between electrodes, known as breakdown, limits the design of linear accelerators, and as such is a focal topic of the prospect study for a future compact linear accelerator (CLIC) in CERN. 21 CLIC is planned to operate at low breakdown rates (BDRs) with electric fields of 100 MV/m and stronger applied between OFHC Cu electrodes.…”

Recent progress and perspectives of space electric propulsion systems based on smart nanomaterials

“…The difference is that in the case of self-healing, the deposition of plasma-nucleated nanomaterials (most probably, as small as possible) or appropriate ions (e.g., silicon oxide formed in plasma with silane added) should be ensured at proper places (in wear damage locations only), and moreover, certain surface processes should be activated and sophisticatedly controlled to conduct efficient wall healing, i.e., surface repair by the controlled re-deposition of the nanomaterial. Importantly, the first experiments have demonstrated this mode in the thruster-like conditions 115 .…”

“…Similar systems often use a special consumable electrode or even more complex device to maintain the readiness to produce discharge (and hence, to supply the pulse of thrust); in our case, a primary function of the system was maintained by the system’s behavior, thus demonstrating self-healing at the level of the material. Adapted with permission from Teel et al 115 . Copyright 2017, AIP.…”