Elettra-Sincrotrone Trieste, 34149, Basovizza (TS), Italy.
Elettra-Sincrotrone Trieste, 34149, Basovizza (TS), Italy and University of Liverpool, Department of Physics, Liverpool, United Kingdom and Cockroft Institute, Sci-Tech Daresbury, Warrington, United Kingdom.
Phys Rev Lett. 2014 Apr 4;112(13):134802. doi: 10.1103/PhysRevLett.112.134802. Epub 2014 Apr 2.
Control of the microbunching instability is a fundamental requirement in modern high-brightness electron linacs, in order to prevent misleading responses of beam optical diagnostics and contamination in the generation of coherent radiation, such as free electron lasers. We present the first experimental demonstration of control and suppression of microbunching instability by means of particles' longitudinal phase mixing in a magnetic chicane. In the presence of phase mixing, the intensity of the beam-emitted optical transition radiation, which is used as an indicator of the instability gain at optical wavelengths, is reduced by one order of magnitude and brought to the same level provided, alternatively, by beam heating. The experimental results are in agreement with particle tracking and analytical evaluations of the instability gain. This article is extended to a discussion of applications of magnetic-phase mixing to the generation of quasicold high-brightness ultrarelativistic electron beams.
控制微束不稳定性是现代高亮度电子直线加速器的基本要求，以防止束光学诊断的误导性响应和相干辐射（如自由电子激光）的污染。我们首次通过在磁扭摆中进行粒子纵向相混合的方式展示了控制和抑制微束不稳定性的实验演示。在存在相混合的情况下，光束发射的光跃迁辐射的强度（该强度用作光学波长下不稳定性增益的指示）降低了一个数量级，并降低到通过束加热提供的相同水平。实验结果与不稳定性增益的粒子跟踪和分析评估一致。本文还扩展到讨论磁相混合在产生准冷高亮度超高相对论电子束方面的应用。
