离子通道中的虚阴极辐射∗

摘要

A novel electromagnetic (EM) radiation regime, the plasma-based multistage virtual cathode radiation model is proposed. Recent study indicates that, as an electron beam passes through a high-dense ion background, due to the cooperation of the ion background and the modulation of the virtual cathode formed at the focusing point, a multistage virtual cathode can be formed. Further studies show that the electrons reflected at different stages of the virtual cathode will come into oscillation, and the EM radiation will be excited, which is different from the betatron emission in an ion channel. As an example, a beam-ion channel system bound in a cylindrical cavity is studied by using particle in cell simulation. It is confirmed that a multistage virtual cathode is formed and EM radiation is induced. Finally, the characteristics of the radiation are discussed in the present paper.%提出了一种新型的基于等离子体的多级虚阴极振荡器物理模型并展开了研究。研究表明：当电子束通过稠密等离子体背景时，由于离子背景和焦点处虚阴极的共同作用，得以形成多级虚阴极；多级虚阴极对电子的作用，使电子在各级之间振荡，从而产生高功率微波辐射。这是与离子通道横向的betatron振荡完全不同的一种辐射机理。通过质点网格(particle in cell)法模拟验证了多级虚阴极的形成，模拟中发现，所选参数TM024模被激发起来。最后，在所建模型的基础之上对辐射特性做了详细分析。