论文标题:虚火花放电的粒子模拟及等离子体对电子束聚束特性研究
论文作者
论文导师 蒙林,论文学位 硕士,论文专业 等离子体物理学
论文单位 电子科技大学,点击次数 245,论文页数 69页File Size1782K
2006-05-01论文网 http://www.lw23.com/lunwen_1421317/
pseudospark ; hollow cathode; PIC-MCC; annular electron beam
近些年来,由于军事和科学研究对更高功率、更高能量更高频率微波源的需求,强流电子束技术成一门新兴技术。虚火花放电等离子体电子枪由于其工作电压高、放电电流强度大、放电产生的离子不直接轰击阴极等诸多优点,有望成为一种新型的电子束源。然而,到目前为止,虚火花放电的具体机制尚不清楚。为了辅助强流电子束聚焦,等离子体被引入聚束系统中,降低了对磁场的要求。本文主要围绕虚火花放电过程及等离子体对电子束的聚束作用,进行了一些研究和探讨,主要具有以下内容: 1.概述了虚火花放电的特性,如工作气压和击穿电压等。对处理碰撞问题的蒙特卡罗方法作了详细的阐述。 2.利用蒙特卡罗碰撞加粒子模拟的方法,对虚火花放电过程进行了粒子模拟,探讨了在不同的放电阶段空心阴极效应的作用。比较了在不同气压和空心阴极孔径下虚阳极的形成时间和扩展速度。 3.在薄环形束的近似下讨论了等离子体对空心电子束的聚束作用。求解了环形束内不同等离子体分布情况下电子束在等离子体中的包络轨迹。在环内中性等离子体情况下计算了传输过程中的两个重要参量——平衡半径和空间电荷力平衡半径,讨论了电子束的传输特点。还在此情况下计算了在不同填充因子情况下电子束外包络的上下幅度差和传输周期,提出了实现空心电子束小脉动、长周期传输的选择填充因子的方法。 4.对环形电子束入射等离子体时的内外包络轨迹进行了粒子模拟。
In recent years, the high power electron beam source technology, as a new technology, has been developed quickly because of the continuing demands of higher power, higher energy and higher frequency microwave sources in military and scientific research. The pseudospark electron gun works at high voltage and can produce high power electron beam. The ions produced by discharges do not bomb the cathode directly. With so many advantages, the pseudospark electron gun is prospective to be a new kind of beam source. However, the principle of pseudospark discharge is still not very clearly. In order to enhance the high power electron beam focusing, plasma is introduced into focusing system, so the system can operate without a guiding magnetic field. In the dissertation, the properties of pseudospark discharge and the focusing effect of plasma is studied. The main works are as follows: 1. Outlining the characteristics of pseudospark, such as pressure and breakdown voltage. The Monte Carlo collision model is described in detail. 2. The pseudospark discharge is simulated with the PIC-MCC method. The virtual anode formation time and propagation velocity at different pressure with different apertures are investigated. 3. Based on thin annular electron beam approximation, the focusing effect of plasma is investigated. The inner and outer envelops of the annular beam are also derived under different plasma electrons distributions. Two important parameters–balance radiuses and space charge force balance radius is calculated under neutral plasma case. The properties of electron beam transmission are discussed. The transmission period and the amplitude between the peak to peak with different plasma–filled factors are presented. The optimized method of plasma–filled factor to get a small amplitude and long period length electron beam is suggested. 4. The inner and outer envelops of the annular beam in plasma are simulated with PIC code.
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