Spectroscopic investigation of prebreakdown phenomena in liquidnitrogen under impulse voltage

摘要

This paper reports the results of experimental investigationsabout prebreakdown phenomena in liquid nitrogen, in point-planeelectrode geometry (gap distance: 2 mm) under impulse voltage (up to 30kV). As in hydrocarbon liquids, slow “bush like” streamersand fast filamentary streamers are observed in positive polarity. Thespectral analysis of the emitted light during the propagation offilamentary streamers shows the second positive band emission system ofnitrogen (C3II_u→B3II_g)in the region 330 nm to 400 nm. The rotational and vibrationaltemperature T_r and T_v can be evaluated from acomparison of experimental and simulated spectra of vibrational bandsfor the transition Δv=-2 of the second positive system. From thesemeasurements, we can conclude that the temperature of gaseous filamentsis about 540 K, i.e. a quite cold plasma