Experimental study on Langmuir probe diagnosis of plasma based on data acquisition system
Many parameters of plasma,such as electron temperature and ion density can be calculated according to the voltage-curren characteristics curve measured by Langmuir probe.A plasma scanning power system and a data acquisition system are applied in this experiment which could acquire,save,analyze and display data in real time.The data acquisition system is a virtual instrument system,composed of three sections as data acquisition,analysis and results display.It is used to acquire the Langmuir probe's current and voltage signals,as well as analyse and process them.The entire testing process finishes in time of ms level.Compared with meanual test,Langmuir probe test based on data acquistion system could gain more accurate data in a larger voltage range(-100~100 V).Moreover,it can avoid the curve distortion produced by plasma voltage drift.Further studies indicate that with the increase of the gas pressure in vacuum chamber,the electron temperature decreases,while the ion density increases.