Spatial Distributions of Plasma Temperature in Hollowneedle-Plate Discharge

A 3cm long plasma torch is generated when argon gas is introduced by using a hollowneedle-plate discharge device working in atmosphere. The electron excited temperature, vibrational temperature and the gas temperature at different positions of plasma torch are studied by using optical emission spectrum. The gas temperature is obtained by comparing experimental line shape of OH radicals band around 309nm with its simulated line shape. The vibrational temperature is calculated using second positive band system. The electron excited temperature is obtained by the ratio of the spectral lines of Ar I 763.5nm and Ar I 772.4nm. It is found that the gas temperature is 310K at different positions of plasma torch, vibrational temperature increases from 1740K at arc root to 1790K at arc tip, and electron excited temperature decreases from 4200K at arc root to 3250K at arc tip.