High-voltage discharge in nitrogen at high pressure and photoionization effect

The data of experimental study of impulse high-voltage breakdown in nitrogen at high pressure (P=10-60 atm), obtained at the electric field strength E up to 10⁷ V/cm and pulse rise-time τ=0.4-20 ns, are compared with the avalanche theory results. It is shown that traditional description of breakdown using only the impact ionization mechanism does not agree with the experiment in a wide range of the parameter E_BD/P(Pτ). Taking photoionization into account it is possible to obtain satisfactory phenomenological description of the breakdown process for τ=5-20 ns.