Design Of Drive And Control Circuit For Glow Discharge Plasma Excitation Source

Glow discharge optical emission spectrograph (GD-OES) is a kind of modern analyticalinstrument, which is used in the element detection of material surface. GD-OES has alreadybeen an effective instrument for its ability of analyzing solid sample directly and for surfacedepth analysis. GD-OES has been wildly used in the research of coating material and materialsurface treatment, the testing technology of industrial product, and the determination ofprocessing parameter etc. There are a few manufacturing companies of GD-OES in the world ,and no one have produced commercial instrument of GD-OES in china .Therefore, theresearch on GD-OES instruments and its related technology is very necessary.Glow discharge excitation source is one of the main focuses in the research of GD-OES.This task makes the research on making a high voltage constant current source and designingauto control system for glow discharge excitation source.This thesis presents a GD0411-type high voltage constant current source with highstability, which is used in driving Grimm-type glow discharge plasma excitation source. Theopen circuit voltage of the constant current source is 1.1KV and the output current can becontinuously controlled from 0 to 100 mA. The regulation rates of load and input voltagechange are both better than 0.05%. Good sputtering result of metal sample is obtained withGrimm-type glow discharge plasma excitation source, which is successfully drove by thisconstant current source. Surface topography picture of sputtering crater, photograph andsputtering rate(10nm/s～140nm/s)in different sputtering condition are provided. Cr, Cu, Al,and W of GBSA6800x stainless steel standard sample have been tested, better than 2.5%RSD were achieved.An automatic control system for glow discharge plasma excitation source is designed. Itcontains the computer control of radio frequency power source, the voltage control and dataacquisition of high voltage constant current source, and the auto control for the other part ofglow discharge source. The auto control circuit and computer control program is alsoprovided in this thesis. By applying computer control method, the discharge voltage accuracyis less than 2%FS.