Townsend ionization coefficients in compressed nitrogen

Pre-breakdown currents in compressed nitrogen have been measured as a function of gas density ρ and electric field E . Values of the first ionization coefficient η have been deduced by comparison with published data obtained at lower pressures. While values of η increase with E /ρ, as at low pressure, values of the secondary coefficient γ show a slight increase with decreasing E /ρ, which is the reverse of the trend at low pressure. The implications are discussed briefly.