六硼化镧低压气体放电特性研究

【作者】 郭靖扬；

【导师】 陈泽祥；

【作者基本信息】 电子科技大学 ， 物理电子学， 2006， 硕士

【摘要】 开关元件是脉冲技术和脉冲功率技术中重要的元器件,其参数和特性对脉冲的上升时间、幅值等产生最直接、最敏感的影响。目前处于试验中或者投入实际应用的开关元件很多,如火花放电间隙、闸流管、引燃管等,它们有不同的结构、原理和优缺点,应用在不同的场合和领域。随着脉冲功率技术的发展,对高性能开关元件提出了更高的要求。具有耐受高电压强电流、击穿时延短而分散小、电阻和电感小、电极烧损少以及能在重复脉冲下稳定工作的各种类型的开关元件的研制,是当前一个十分受重视的研究课题。真空开关管、火花开关、伪火花放电管都是利用气体放电理论的开关元件,具有高耐压能力、高峰值电流、功率大等优点。目前实际应用的开关管多数工作在火花放电区域(巴邢曲线的右支),使用的电极材料一般为钨、钼、不锈钢、水银、石墨等。本文研究了以六硼化镧为电极材料时的气体放电特性。分析直流工作条件下,以氩气、氮气、氦气为工作气体时,气体的压强、极间距对着火电压和管压降的影响,并制作低气压(<10Pa)下的气体放电开关管(放电气体为氮气和氦气,极间距为5mm),研究其在直流和脉冲下的放电特性,以及放电过程对电极的影响。结果表明,随着电压的升高,六硼化镧放电管的放电机理由辉光放电转变为弧光放电,放电电流突然迅速升高,管压降大幅下降。氦气放电管在脉冲工作状态下可以长期稳定放电,2200V时,峰值放电电流可超过100A。在放电过程中,阴极表面有离子的清洗和活化作用,可以使电极逸出功降低,提高放电管的放射能力和稳定性。本文的研究表明,六硼化镧作为气体放电电极具有寿命长、延迟时间短、放电电流强等优点,可用于开关管等重复脉冲气体放电器件。更多还原

【Abstract】 The switches are crucial components in pulsed technology and pulsed power technology, whose parameters and characteristics have the most sensitive and direct impact on the breakdown delay time and amplitude of pulse. Nowadays, the switches which are being studied or applied, such as gas spark gap, thyratron and ignitron, etc, are of different structures, operating principles, advantages and disadvantages, and are applied in various situations and fields. As the developments are made in pulsed power technology, there is more rigorous desire for better capability switches. The study in various switches with high voltage, high current, fast turn-on time, low jitter, low resistance, low inductance, low erode rate and being capable of steadily work with pulse repetition-rate, is currently a subject of growing interest.Vacuum switchgear tubes, gas spark gaps and pseudospark tubes are all switches of gas discharge theory, and have the good qualities of high withstanding voltage, high amplitude of current and high power. Most of the switch tubes used presently work in the gas spark region (the right branch of Paschen curve), and are made of graphite and mental such as tungsten, molybdenum, stainless steel and mercury.The presented thesis studies the gas discharge of LaB6 electrodes, The paper analyses the impacts of gas press and electrodes separation on the ignition voltage and voltage drop, and makes low gas pressure, lower than 10Pa, discharge switch tubes, with gas of helium and nitrogen, electrodes gaps of 5mm. The paper studies the tubes’discharge performances, and the impacts of discharge process on the electrodes. The results show that as the voltage rises, the tubes’discharge mechanism changes from glow discharge to arc discharge, the current rises suddenly and the voltage drops a lot. The tube with helium can work long time and steadily under pulses, with the voltage of 2200V, the peak value of current can exceed 100A. In the discharge process, the ions can clean and activate the surfaces of cathodes, which can reduce the work function of the electrodes, and improve the discharge tubes’emission capability and stability.The results of the presented thesis show that, as electrode, LaB6 has the更多还原