Optical Emission Spectroscopy To Measure The Nitrogen Dc Glow Discharge In The Rotational Temperature

Measurements of rotational temperature as low as several hundred Kelvin have been achieved using optical emission spectroscopy (OES) in nitrogen DC glow discharge. The strongest band of the first negative system of nitrogen molecule ion was chosen to determine the rotational temperature of nitrogen DC glow discharge at 4 different positions in the discharge area: back of the cathode; cathode sheath; positive column and anode glow region. In positivecolumn the rotational temperature of N^ increases apparently with theincreasing discharge voltage from 500F-1100F when the pressure is lOPa . However at pressure of 20Pa the rotational temperature in positive column increases slightly with the increase of discharge voltage. On the contrary, the rotational temperature in cathode sheath takes reverse tendency when the discharge voltage varies from 500F-1100F. As regard the anode glow region, the rotational temperature at lOPa decreases with the increase of discharge voltage, but that at the 20Pa increases. We attribute the different changing tendencies of the rotational temperature to the different discharge status at different pressure. When the discharge voltage varies from 500F to HOOF, the discharge at pressure of lOjPa is impediment glow discharge and that at 2QPa is abnormal glow discharge. We have also explained the discharge state microscopically using the rotational temperature determined by OES.