Determination of the electron concentration and temperature, as well as the reduced electric field strength, in the plasma of a high-voltage nanosecond discharge initiated in atmospheric-pressure nitrogen by a runaway electron beam

We report on the results of spectroscopic measurements of electron concentration N_e and temperature T_e, as well as the reduced electric field strength E/N in the plasma of a high-voltage nanosecond discharge in the gap with a strongly nonuniform electric field distribution, which is filled with nitrogen under the atmospheric pressure. The possibility of using the method for determining T_e and E/N, which is based on the determination of the ratio of the peak intensities of the ionic N₂ ⁺ (λ = 391.4 nm) and molecular N₂ (λ = 394 nm) nitrogen bands, is proved. We detected the mean values of quantities N_e, T_e, and E/N amounting to ∼2 × 10¹⁴ cm^-3, ∼2 eV, and ∼240 Td, respectively. In addition, the dynamics of these quantities is determined.