Experimental and theoretical studies of the direct-current breakdown voltage in argon at micrometer separations

In this paper, the dc breakdown in argon has been measured in the discharge system consisting of two parallel planar Cu electrodes at separations from 20 to 500 μm varying the pressure from 4.5 to 690 torr. The measured breakdown voltage curves were systematically analyzed and a corresponding scaling law was suggested. The estimation of the secondary emission coefficient γ as a function of the reduced electric field was based on experimental data and simple theoretical studies. Additionally, particle-in-cell/Monte Carlo collision simulations were performed to understand in more detail the processes involved in the dc discharge breakdown. Good agreement was found between experimental and simulation results.