Development And Application In Hollow Cathode Discharge Of The Electrostatic Probe Diagnostic System

Plasma diagnostics,the essential means to measure its property and state parameters,is an important issue in research and application of discharge plasmas.Electrostatic probe is one of the main measures to obtain the plasma density and electron temperature,especially in low pressure plasmas.However,the condition for using electrostatic probe is not the same under different discharge pressures and plasma density,so that one should make appropriate selection according to different work environment.In this thesis,we focus on the electrostatic probe of different size for hollow cathode discharge plasma and make a comparison of the results with the other methods.A diagnostic system of electrostatic probe with single-probe and double-probe as well as the corresponding matching sampling circuit are designed based on the theory of electrostatic probe.We firstly use them to measure directly the plasma parameters in the low-pressure DC hollow cathode discharge,to observe and analyze the fitness of voltage-current curve of probe with theoretical curve.Then,we adjust the size of probe to measure the plasma parameters more effectively in hollow cathode discharges under different pressures,so that we can get the optimized probe conditions.The experimental results are compared with that of microwave interference method.Finally,we give some comments on the relationship between the applicable conditions and scope of electrostatic probe and the gas pressure and electron density.