Design Of 5kV Direct Current High Voltage Power Supply For TOF-SIMS

Through the concentrated ion beam, the ions source of time of fly-secondary ion mass spectrometry(TOF-SIMS) impacts on the surface of the sample and make it splash out secondary ion. Then these ions are collected by the mass analyzer. According to the different nucleoplasm, mass analyzer classifies the ions, then achieving the mass spectrometry separation. As a kind of mass spectrometry, TOFSIMS has been widely used in several fields such as semiconductor, geology, food science and biology because of its highly resolving power and sensitivity. As a major component of TOF-SIMS, the high voltage power supply could extract secondary ions from sample surface and accelerate them. Its function has direct impact on the instrument resolution. Based on the project of "National Major Scientific Instrument and Equipment Development Special Projects-TOF-SIMS Scientific Device dedicated to isotopic geochronology", this thesis will develop a high voltage power supply suiting for TOF-SIMS including the following aspects: the selection of the main circuit topology, design of the cell circuit, the simulation and parameter optimization the high voltage power and the physical testing. This thesis sections as following.Firstly, according to the requirement of TOF-SIMS system, the overall design scheme of the high voltage power supply is put forward, combining high frequency inverter technology and the voltage doubling circuit technology. Taking advantage of specificity of one-way electric conduction of diode, the voltage doubling rectifier circuit will accumulate more charge and output DC high voltage as several times as transformer secondary voltage. Despite for reducing transformation ratio, this method effectively decreases the transformer distribution parameters influence and achieves higher output voltage. Secondly, according to the overall design scheme of high voltage power supply, the design criteria as well as the applicable conditions, the main circuit topology of the high voltage power supply is determined, including the selection of the chopper voltage regulation circuit and the inverter circuit topology. As the main structure of the high voltage power supply, the selection of the high frequency voltage transformer should observe to the area method while the selection of doubling voltage circuit must comply with transformer design manual. At the same time, according to the characteristics of high voltage power supply the doubling voltage circuit will be refined. Besides, based on Multisim circuit simulation software, the high voltage power supply would be virtually simulated. Finally, the printed circuit board(PCB) will be designed based on the principles of anti-electromagnetic interference and schematic diagram of high voltage power supply. Then it will be used to test high voltage power supply on unit circuit and overall performance. And the results will be analyzed to demonstrate whether the project is feasible or not.