Development Of Discharge Power Supply For Double Plasma Ion Source

Secondary ion mass spectrometry(SIMS)is a kind of analytical chemistry is very important in the test method,has high quality,high detection sensitivity and resolution trace analysis of micro zone etc.,are widely used in analytical chemistry,life science,environmental science and earth science and other fields.By the ion source,the quality of the secondary ion mass spectrometry of analyzer and detector system,when the secondary ion mass spectrometry was applied to rare earth element and geochronology analysis,is to be able to provide O-ion beam is often used to double plasma ion source.The discharge power supply is one of the important components of the plasma ion source.It is an energy source that produces an ion beam and keeps the beam continuously stable.Once the ion beam is extracted directly from the discharge current,the stability of the discharge current and the magnitude of discharge current can affect the stability and strength of an ion beam.The paper is based on the project of the special "isotope geochronology special TOF-SIMS scientific device" for the development of national important scientific instrument and equipment,and it is of great significance to develop the discharge power supply for this instrument.According to the actual demand and working mode of the discharge power supply,the overall scheme of the discharge power supply is designed,including the selection of the topology of the main power supply circuit and the choice of the power control scheme.By analyzing the characteristics of different types of topology,the topology of the full bridge converter is selected as the topology of the main circuit of the power supply.The power control scheme includes the mode of power supply modulation,the switch control mode of the converter and the mode of the power supply feedback control.The phase-shift PWM control circuit is chosen as the control mode of the power supply,which can effectively reduce switching loss and switching noise of the circuit.According to the overall design of the power supply,the main circuit and power control and protection circuit of the power supply are developed respectively.Each module in the main circuit is designed and tested,including rectifier and filter circuit,coupling isolation drive circuit,full bridge inverter circuit,high frequency transformer,high frequency rectifier filter circuit and voltage release circuit,and each module in control and protection circuit is designed and tested.,including phase shifting PWM control circuit,constant voltage control circuit,constant current control circuit,constant voltage constant current clamp circuit and protection circuit.Through the integration of the circuit,the power supply is tested,including the power index parameters and performance parameters,the output voltage 0~-2000 V adjustable,the output current 0~200mA adjustable,the maximum power 400 W,the current load adjustment rate 0.08%,the output voltage adjustment rate 0.06%,and the technical requirements of the TOF-SIMS-REE instrument to the discharge power supply.The discharge power and the instrument are tested.Through 4 hours of test,the intensity fluctuation range of one ion flow is within 220 pA,indicating that the power supply is stable on the instrument;the first ion beam is the strongest when the discharge current is around 100mA;the test results of the standard zircon sample show that the power supply can be used.Use the instrument to carry out the related experiments.