Microwave breakdown of low pressure N_2 gas in microgaps

摘要

The pressure dependence of the breakdown of nitrogen gas by a microwave field in microgaps down to 13 μm has been measured. Fits to a phenomenological function suggest that microwave breakdown in small gaps requires a higher collision frequency, vc. If the effective electric field on an electron in a microgap is interpreted as E_(eff) = E_o((v_c~2/(v_c~2+ω~2))~(1/2) and then as the gap size is reduced, we find that the collision frequency needed to produce a minimum breakdown electric field shifts from v_c = ω for large gaps to v_c = 2ω for small gaps.