Lasing and the dynamics of a nanosecond discharge in nitrogen

The speed of the ionizing waves in nitrogen was measured at pressures of 0.1-100 kPa with a 250 kV amplitude for the negative-polarity pulse. The maximum speed of 2 x 10 to the 10th cm/sec was obtained at a pressure of 2 kPa. These measurements were compared to those of earlier studies (Winn, 1967; Anderson, 1971); it is found that the speed increases with the pulse amplitude. Moreover, a maximum speed is attained at a higher pressure at the higher voltages, but with an approximately constant U/p, where U is the pulse amplitude. The wave propagation was accompanied by lasing at wavelengths of 337.1 nm. Examined in the 0.1-10 kPa range, this lasing showed a maximum peak power at about 4 kPa. The delay between the lasing and the voltage of the cathode or the current signal at the anode was also measured.