DC High Voltage Constant Current Source For Glow Discharge Spectrometer Excitation Source

DC glow discharge is an important form of gas discharge phenomenon.It plays a very important role in studying the characteristics of plasma.It is widely used in various fields such as plasma lighting,surface modification of materials,and film deposition.DC glow discharge can not only work alone,but also can work in combination with other discharge methods such as radio frequency and ns.Due to its wide application,a lot of researches have been done on DC glow discharge spectrometers at home and abroad.Grimm-type glow discharge excitation source is the most widely used excitation source in glow discharge spectrometer.This excitation source was proposed and designed by Grimm in the 1960 s.Grimm-type glow discharge light source requires 0 ~ 100 mA continuously adjustable DC high voltage constant current source.Although the working voltage of glow plasma is about 0.5 ~ 1 kV after ignition,higher voltage is needed during ignition,usually Only when the open-circuit voltage of the constant current source reaches 1.5 kV can reliable ignition be guaranteed.Based on the DC high-voltage constant-current source with an open-circuit voltage of 1.1 kV,which was developed in the past,it was improved.The improved high-voltage regulator uses two high-voltage field-effect transistors with a drain-source breakdown voltage of 4.5 kV to increase the open-circuit voltage of the constant current source from 1.1 kV to 1.5 kV.The STC8A8K64S4A12 microcontroller was used to design the digital control system circuit.The PID control method was added to the constant current negative feedback adjustment circuit and simulated using simulink.The simulation results showed that the PID control algorithm is added to the negative feedback to further reduce The system error was reduced and the stability of the output current was improved.According to the DC high-voltage rectification filter circuit designed in this paper,the constant current adjustment circuit,and the corresponding protection circuit designed according to the actual working conditions,PCB wiring,welding,and assembly into a constant current system circuit.The self-developed high-voltage constant current source was used as a DC power source to connect with Grimm-type glow discharge light source,and the Ava Spec-2048 miniature CCD optical fiber spectrometer(Ava Spec-2048 Miniature produced by Avantes BV)was used.Fiber Optic Spectrometer)is used as a spectroscopic and photoelectric detection system to form a DC glow discharge analysis system.After experimental tests,the open circuit voltage is ?1.5 kV,and the output current is continuously adjustable from 0 to 100 mA.When the input AC voltage changes from 160 V to 240 V,the voltage adjustment rate is ?0.035%.When driving a 1 k? to 11 k? resistive load,the load adjustment rate is ?0.033%.The Grimm-type glow spectrometer excitation source was driven by an improved high-voltage constant current source.For Fe,Cd,Mo,W and other samples in copper alloys and Copper belt and Galvanized iron sheet.the relative standard deviation(RSD)of the test results were all less than 2%,and the performance indicators are good.