Based On The Optical Switch Nanosecond Pulse Power Source Technology Research

Electric magnetic field affects activities of organism. Recent research shows that ultra-fast pulsed electric field (strenghth as high as100kV/cm, pulse width as short as10ns or less) can induce non-thermal intracellular physical effects, such as change of cell structure and function, Ca+burst, enhancement of gene expression, programmed cell death (apoptosis). The effect has been proved to trigger cancer cell apoptosis and tumor shrinkage, which becomes a hot spot of cross research field between physics and biomedical science. And the aquirement of ultra-fast pulse electric field plays an important role in the investigation. A pulsed source has been developed in this dissertation. Photoconductive switches (PCSS) and solid Stacked Blumlein Line (SBL) are used as main components for pulse forming.PCSS has many potential applications due to their advantages such as high power capability, high repetition rate, fast rise time, and negligible time jitter. Lateral and vertical structures are designed to study the characteristics of GaAs PCSSs and SiC PCSSs. An innovative triggering method is designed and has been proved to be highly effective in lifetime prolonging. High-power GaAs PCSS with an operating voltage of26.4kV and a photocurrent of4.3kA is obtained. SiC PCSS working under electric field of250kV/cm (10kV/90kA) is acquired.Four stages of SBL are chosen as main circuit of pulsed source. Four GaAs PCSSs are employed as pulse forming switches. Parameter calculation is given and circuit simulation is conducted subsequently. Pspice simulation reveals that switch parameters (turn-on resistance, conducting time and inductance), circuit inductance and isolation resistance contribute to amplitude and rising time of the output waveform. Pulsed charging is adopted for its benefition to PCSS lifetime. Laser system is used to trigger four PCSSs. Experiments show that under nanoseconds triggering pulse,53.6kV voltage is obtained under charging voltage25kV, with whole efficiency52%, pulse forming efficiency74%; under picoseconds triggering pulse,53kV voltage is obtained under charging voltage of23.5kV,, with whole efficiency52%, pulse forming efficiency up to69%. The high on-state resistance of PCSS is a major factor causing low voltage efficiency.Further work will be focused on pursuing possible way to reduce on-state resistance of PCSS. At the same time, attention will be paid to explore technical way to enhance overall performance of the pulse source.