The Design And Implementation Of High Voltage Control System In Secondary Ion Mass Spectrometry

Secondary ion mass spectrometry (Secondary-ion-mass spectroscope SIMS),which itself has some of the energy for the surface of ion beam bombardmentsample, the sample of the surface atomic sputtering out become electricallycharged Secondary ion, then use magnetic analyzer/quadrupole energy filterscomposed of the analysis of the ion by mass spectrometry/mass than, can knowthe composition of the surface elements samples and ingredients. Large secondaryion mass spectrometry (SIMS) device, is the cutting edge of the surface analysistechnique. It can take a few seconds on the surface of the local area to scan andanalysis, generates a surface composition figure. It has been widely used in thefield of chemistry and isotope analysis.In The secondary ion mass spectrometry (SIMS), the ion source, optical ionsystem, secondary ion flight pipeline, quality analyzer, each part of the need forhigh voltage to ionization ion on, acceleration/deceleration, deflection, focus onphysical process, etc. So high voltage circuit is the foundation of the whole system.And takes an important part in the whole secondary ion mass spectrometry (SIMS).The master’s thesis comes from the key project named “secondary ion massspectrometry (SIMS) is the core technology and key components research anddevelopment “which is the "eleventh five-year plan" of national science andtechnology. High voltage generating circuit is one of the important part of theperformance of a direct influence on the ion of output, an ion beam spot size, acurrent of ion beam intensity and secondary ion energy screening precision andinstruments such as the resolution of the overall index. The research of the subjectincludes: ARM circuit which is the core of the high voltage generating circuit and itsperiphery circuit; DA conversion circuit and the high voltage power circuit of thehardware design and the Linux drivers under preparation; The test of High voltagegenerator in the practical application, and its reliability testing. This research hassome reference value to the technology of secondary ion mass spectrometry(SIMS)’s research.The requirement for precision in Secondary ion mass spectrometry (SIMS) ishigh. At present, the minimum precision for each part must be greater than0.05%.Therefore, the high voltage sources must have a higher accuracy. In this paper,according to the requirements of the system are mainly about a few research.First, put forward the high voltage circuit happened overall design scheme. Thissubject includes: the core ARM circuit of AT91RM9200; AD5725chip consists of thedigital-simulation voltage transform circuit; Rear high voltage control circuit andthe high voltage power supply module integral circuit.Second, given the design of the core board and peripheral ARM circuit, DA conversion circuit, and the high voltage control circuit’s hardware. The core boarduses AT91RM9200of Atmel company as the control core of the whole circuit. itsresponsible for receiving the user’s commands, according to the correspondingcommand, control DA output, so as to control the output of different high pressure.According to the mission of high voltage requirements for accuracy is not less than0.05%. We calculated the minimum digits DA transition chip for twelve, INL not lessthan1LSB. So we use the AD5725of Analog Devices company as DA conversion ofthe circuit core chip. its responsible for the digital quantity control board read fromARM, and then into the simulation control volume. High voltage control circuit isresponsible for the amplifier of the output from DA circuit. And the impedancematching of the control signal and the high voltage power supply.Again, introduced the configuration and cutting of Linux operating systemkernel and the transplant to its hardware platform. Then focuses on the methodand procedure of Linux system character device driver programming. At the sametime gives the driver and the writing of the application of AD5725chip in the Linuxoperating system.Finally, Gives the detailed applied test to the whole system. Main includingcore board hardware circuit functional test; dynamic parameters and staticparameters of the D chips’ test; For the test of±250V high pressure,300V-2.5KV high pressure,-10KV~10KV voltage output current, voltage ripple voltage andthe stability. Among them, the AD5725INL less than0.4LSB, meet the systemrequirements.±250V voltage ripple voltage is0.004%, the voltage stability is0.007%;300V-2.5KV voltage ripple voltage is0.004%, the voltage stability is0.04%;-10KV~10KV voltage ripple voltage is0.003%, the voltage stability is0.04%; Allreached the target. The whole high voltage system to happen on experimentaltransplant SHRIMP. the Test of the stability and precision achieves a highstandards.