Forming of Space Charge Wave with Broad Frequency Spectrum in Helical Relativistic Two-Stream Electron Beams

• Published in: Chinese physics letters Vol. 34; no. 7; pp. 150 - 154
• Main Authors: Lysenko, A., Volk, I., Serozhko, A., Rybalko, O.
• Format: Journal Article
• Language: English
• Published: 01.06.2017
• Subjects: 双流不稳定性; 束宽; 相对论电子; 空间电荷; 自由电子激光器; 螺旋; 非线性理论; 频谱分解
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/34/7/075202

We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave （SCW） harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.