ENHANCEMENT OF HIGH-POWER MM WAVE RADIATION BY THE BEAM-PLASMA INSTABILITY IN A DIELECTRIC-LOADED WAVEGUIDE

介电波导中束流等离子体不稳定性增强高功率毫米波辐射

• 批准号: 09680457
• 负责人: MASUZAKI Masaru
• 金额: $ 1.92万
• 依托单位: KANAZAWA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09680457/
• 关键词: microwave generation; intense relativistic electron beam; Cherenkov instability; cyclotron-Cherenkov instability; plasma-filled waveguide; beam-plasma instabilities; current amplification; 高出力ミリ波; 相対論的電子ビーム; プラズマ・チェレンコフ自由電子レーザー; プラズマ・サイクロトロン・チェレ

1. THEORETICAL ANALYSIS(1) We derived a dispersion relation for waves excited by an intense monoenergetic linear relativistic electron beam (IREB) in a plasma-filled dielectric-lined cylindrical waveguide immersed in a finite magnetic field. Finding is that, in addition to the Cherenkov and cyclotron-Cherenkov instabilities which can be excited in a vacuum waveguide, the beam-plasma instabilities are also excited. These instabilities are due to coupling of slow space-charge waves and slow cyclotron waves on the beam with Trivelpiece-Gould modes in the plasma.(2) We analyzed numerically the dispersion relation and derived frequencies and growth rates of these instabilities.(3) When the plasma frequency is lower than the electron cyclotron frequency, enhancement of the growth rates of the Cherenkov and the cyclotron-Cherenkov instabilities due to presence of the plasma are not observed. However, when the plasma frequency is higher than the cyclotron frequency, the growth rates of both in … More stabilities are enhanced, and, moreover, the growth rates of the beam-plasma instabilities are also much enhanced.(4) The growth rates of the latter instabilities are much higher than the growth rates of the former instabilities and we can expect high-power radiation based on this mechanism with broad frequency band.2. EXPERIMENTS(1) We designed and manufactured an experimental device. A plasma was produced by ionizing argon gas introduced into the device with the injected IREB itself. We studied IREB propagation first, and observed current amplification phenomenon when the argon pressure was less than about 100 mTorr. Taking into account results of radiation measurement. we think that this phenomenon is caused by the beam-plasma instabilities.(2) We observed broadband microwave radiation. The total power decreased much for the argon pressure higher than about 100 mTorr. The spectrum of the observed radiation shows contribution from the whole instabilities. This supports the idea that decrease of the total power for the argon pressure above 100 mTorr is due to suppression of the beam-plasma instabilities. Less

1. 理论分析(1)推导了在有限磁场中等离子体填充介质衬里圆柱波导中，强单能线性相对论电子束激发波的色散关系。研究发现，除了切伦科夫不稳定性和回旋加速器-切伦科夫不稳定性可以在真空波导中被激发外，束等离子体不稳定性也可以被激发。这些不稳定性是由于光束上的慢空间电荷波和慢回旋波与等离子体中的trivelpieces - gould模式耦合造成的。(2)数值分析了这些不稳定性的频散关系，推导出了这些不稳定性的频率和增长率。(3)当等离子体频率低于电子回旋加速器频率时，没有观察到由于等离子体的存在而增强切伦科夫的增长率和回旋-切伦科夫不稳定性。但是，当等离子体频率高于回旋加速器频率时，两者的增长率都提高了，而且束流等离子体不稳定性的增长率也大大提高了。(4)后一种不稳定性的增长速度远高于前一种不稳定性的增长速度，我们可以期望基于这种机制的宽频段高功率辐射。我们设计并制造了一个实验装置。等离子体是通过电离氩气与注入的IREB本身一起引入装置而产生的。我们首先研究了IREB的传播，在氩气压力小于100 mTorr时观察到电流放大现象。考虑到辐射测量结果。我们认为这种现象是由束流等离子体不稳定性引起的。(2)观测到宽带微波辐射。当氩气压力高于100 mTorr时，总功率明显下降。观测到的辐射光谱显示了整个不稳定性的贡献。这支持了当氩气压力超过100 mTorr时，总功率的降低是由于抑制了束流等离子体的不稳定性。少

项目成果

M. Masuzaki, H. Tsukuda, N. Toyosugi., K. Kamada, R. Ando, and T. Watanabe.: "Linear analysis of instabilities in a plasma-filled dielectric-lined circular waveguide immersed in a finite axial magnetic field."Proceedings of the 12th International Conferen

M. Masuzaki、H. Tsukuda、N. Toyosugi.、K. Kamada、R. Ando 和 T. Watanabe.：“浸没在有限轴向磁场中的等离子体填充电介质圆形波导的不稳定性的线性分析。

H.Tsukuda,M.Masuzaki et al.: "Instabilities driven by anintense beam in a plasma-fieled dielectric-lined waveguide immersed in a finite axial magnetic field."Proc.of 21st Intern.Free Electron Laser Conf.. (To be published).

H.Tsukuda、M.Masuzaki 等人：“浸没在有限轴向磁场中的等离子场介质衬里波导中由强光束驱动的不稳定性。”Proc.of 21st Intern.Free Electron Laser Conf.（待定）

M.MASUZAKI et al: "Linean analysis of instabilities in a plasma-fieled dielectric-lined circular waveguide immersed in a finite axial magnetic field"to be published in Proc. of the 12th Intern.couf.on High-Power Particle Beams.

M.MASUZAKI 等人：“浸没在有限轴向磁场中的等离子场电介质衬里圆形波导的不稳定性的线性分析”将在 Proc 上发表。

H. Tsukuda, M. Masuzaki, M. Matsuoka, N. Toyosygi, C. Y. Lee, R. Ando, K. Kamada, and T. Watanabe: "Instabilities driven by an intense beam in a plasma-filled dielectric-lined waveguide immersed in a finite axial magnetic field."Proceedings of 21st Intern

H. Tsukuda、M. Masuzaki、M. Matsuoka、N. Toyosygi、C. Y. Lee、R. Ando、K. Kamada 和 T. Watanabe：“由浸没在等离子体填充电介质衬里波导中的强光束驱动的不稳定性