Spatial diagnosis of atmospheric pressure helium plasma jet

Summary form only given. A 6 cm long helium plasma jet torch was generated under atmospheric pressure. A tungsten needle was inserted into the middle of quartz tube and worked as a high HV electrode. The current and voltage of discharge were monitored by an oscilloscope. The spectra of plasma jet were recorded by optical emission spectrum¹. In order to improve the spatial resolution of the optical system, a 0.6-mm-in-diamter field diaphragm is placed in front of optical fiber and ensured a spatial resolution of 6 mm. Intensity of N₂, He and O in axial and radial distribution were investigated. In addition, spatial distribution of rotational temperature, vibrational temperature, electron excitation temperature, and electron density were well studied ². Results showed that He and O intensity decreased with the increase distance from plasma plume root, while N₂ intensity peaked at 3 cm. Spatial distributions of rotational temperature, vibration temperature and electron excitation temperature were similar. They decreased first and then increased with the distance.