Dark-to-arc transition in field emission dominated atmospheric microdischarges

Abstract

We study the voltage-current characteristics of gas discharges driven by field emission of electrons at the microscale. Particle-in-cell with Monte Carlo collision calculations are first verified by comparison with breakdown voltage measurements and then used to investigate atmospheric discharges in nitrogen at gaps from 1 to 10 μm. The results indicate the absence of the classical glow discharge regime because field electron emission replaces secondary electron emission as the discharge sustaining mechanism. Additionally, the onset of arcing is significantly delayed due to rarefied effects in electron transport. While field emission reduces the breakdown voltage, the power required to sustain an arc of the same density in microgaps is as much as 30% higher than at macroscale.

Numerical simulation of the breakdown process of micro-discharge sustained by field emission

“…As the power voltage increases, the discharge transitions from FE mode to arc discharge mode finally. This is our reasonable speculation based on the low voltage, strong current and negative resistance characteristics [58,59]. respectively.…”

“…This is due to the high intensity FE and ionization and the small discharge volume (5.31 × 10 −8 m 3 ) in the micro-discharge. According to the particle density, we calculate the current in 1 ns to be about 17 A, which is roughly equal to the average current from 0 to 1 ns on the figure 9, within a reasonable range of arc discharge current [58,59].…”

“…From figure 2 we can find an interesting result, the discharge directly transitions from pure FE-driven to arc discharge, instead of first transition to glow discharge and then to arc discharge like classical gas discharge theory [57]. This is because when the FE electrons replace the secondary electrons as the discharge sustaining mechanism, the glow discharge will disappear and the discharge will directly transition to the arc discharge under the condition of atmospheric pressure and the gap below 10 µm [59]. This also shows that under small gap atmospheric pressure and high electric field, the arc discharge mode can be achieved only by FE without thermionic emission.…”

“…Yang et al simulated the vacuum arc discharge under pulse and pointed out that the sharp drop in arc voltage in 0.4-0.6 ns is a sign of breakdown [58]. Tholeti et al studied the voltage-current characteristics and the dark-to-arc transition of gas discharges driven by FE of electrons at the microscale [59]. They mentioned that the transition from dark discharge to arc discharge is accompanied by gas breakdown, which can be seen from a drop in voltage and a sudden increase in electron density.…”

Analysis of gas discharge characteristics across micro-gap under different pressures

“…The research on the characteristics of micro-nano gap gas discharge has attracted considerable attention from researchers. [5][6][7][8][9][10][11][12] At present, many researchers have carried out a series of research on micro-gap gas discharge. Some researchers studied micro-discharge from the aspect of electrode structures, 13,14) and many achievements were obtained by numerical calculation and simulation methods.…”