Abstract
Electric discharge across an air gap can be self-healing, providing a unique capability for repetitive, fast, high-voltage/current switching applications through arc conduction. Furthermore, incorporating dielectric granules in the air gap stimulates gas ionization, which lowers the breakdown voltage and narrows breakdown voltage distribution, thereby enabling engineered surge protection from multiple lightning strikes on aerospace vehicles and sensitive solid-state electronics in critical systems. This study investigates the effect of the permittivity of dielectric granules, gap filling, surface roughness, and metal work function on fast-rising, high-voltage breakdowns. In addition to the air gap width, these factors play important roles in gas ionization, field concentration, and initiation of electrical discharge and arcing. Therefore, they could potentially be used to control and narrow operational breakdown voltages for practical applications. Additionally, a modified Langevin–Debye model is developed to correlate the breakdown voltage and the permittivity of the dielectric filler. These investigations identify and highlight key underpinning mechanisms governing the gas discharge behavior across a dielectric filled air gap during voltage surge events.
Highlights
Critical systems, such as those used in aerospace vehicles or life support systems, can be seriously damaged due to unexpected high current surges or lightning strikes
Fast-rising breakdown of air is a stochastic event, in which the breakdown voltage can be tailored by parameters that create localized high field concentration spots in the air gap
The enhanced local field in turn boosts the kinetic energy of charge carriers or ionized species, assists ionization processes for arc conduction, and reduces the breakdown voltage
Summary
Critical systems, such as those used in aerospace vehicles or life support systems, can be seriously damaged due to unexpected high current surges or lightning strikes. Varistors are widely used as a surge protection component, evidence shows that under extreme conditions, these high density, solid components can be permanently damaged by puncture breakdowns, marked by molten and reduced metal at the exit point of the breakdown path. Such vulnerability can be mitigated or remedied by using an air gap, where arc conduction can immediately divert surge currents to ground. Unlike gas-ionization-based devices, such as krytrons and thyratrons, where breakdown voltage is controlled and regulated by a bias grid between an anode and cathode, an empty air gap needs few mechanistically based controls to tailor its breakdown voltage and narrow its distribution for practical engineering applications
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
