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The gas medium (mixture of oxygen and nitrogen in different proportions, under near atmospheric pressure) is excited between parallel plate electrodes in DC electric field with strength lower than needed for the inception of the self sustained discharge. The seed electrons are generated with help of the photo effect irradiating the cathode by pulse laser. The intensities of spectral bands of nitrogen are measured together with waveforms of the discharge current pulses. The main purpose is to measure the ratio of intensities of spectral bands of the 0-0 transitions of the second positive and the first negative systems of nitrogen, dependent on the electric field strength. The comparison of the results of measurement with theoretical calculations enables to make more exact values of coefficients of excitation and quenching of nitrogen states as well as rate coefficients of ionization processes depending on the electric field strength. The results are applicable in the plasma diagnostics for determination of the electric field strength via spectroscopic measurements, and for development of gas discharge based technologies. |