Pre-breakdown evaluation of gas discharge mechanisms in microgaps

Abstract

The individual contributions of various gas discharge mechanisms to total pre-breakdown current in microgaps are quantified numerically. The variation of contributions of field emission and secondary electron emission with increasing electric field shows contrasting behavior even for a given gap size. The total current near breakdown decreases rapidly with gap size indicating that microscale discharges operate in a high-current, low-voltage regime. This study provides the first such analysis of breakdown mechanisms and aids in the formulation of physics-based theories for microscale breakdown.

Cathode fall model and current-voltage characteristics of field emission driven direct current microplasmas

“…Figure 4 shows the potential and electric field profiles obtained from simulations and the proposed model using Eqs. (11) and (12). It can be seen that the agreement is very good except near the edge of the cathode fall where the assumption for linear variation of the electric field becomes inaccurate.…”

“…Venkattraman et al 10 presented particle-in-cell with Monte Carlo collisions (PIC/MCC) simulations and current vs voltage measurements performed on microdevices before breakdown occurs. Several other simulations have been reported dealing with the role of field emission in microdischarges, 11 quantifying the role of various processes in a field emission driven microdischarge, 12 fundamental properties of these microdischarges, 13 and coupling of ion-enhanced field emission and the discharge processes 14 culminating in a scaling law 15 that describes field emission driven gas breakdown without the use of fitting parameters. While most of the above research involved direct current microdischarges, simulations to predict breakdown voltages have also been extended to time-varying fields 16 with different mechanisms contributing to breakdown depending on the applied frequency.…”

Electromagnetic sensitivity analysis of RF gas micro/nano-breakdown

“…The FE is again a boundary process due to the electron tunneling from the cathode surface in presence of strong electric field. This plays a significant role in micro-discharge in gaps narrower than 7 µm [4]. FE current is enhanced by β, which is related to the roughness of the cathode surface and its value has been reported in the range of 1.5−115 in various experiments for atomically rough surfaces [4].…”

“…In atmospheric pressure, it was shown that EII and SEE have dominant roles of micro-discharge in gaps over 10 µm [4]. The FE is again a boundary process due to the electron tunneling from the cathode surface in presence of strong electric field.…”

“…Electron-impact ionization (EII), secondary electron emission (SEE) and field emission (FE) are the main three mechanisms responsible for gas discharge [4] as seen in Fig. 1.…”