Abstract

Evolution of bunching and harmonic power is theoretically studied for a single-pass free-electron laser (FEL) in which electrons are periodically phase-shifted relative to photons in intervals between undulators with harmonics of magnetic field. Analytical calculations are used to reveal the configuration of magnetic field of an asymmetric elliptical and planar undulators that make it possible to suppress the fundamental and amplify several higher harmonics. The evolution of power and bunching is analyzed using a phenomenological model of FEL that describes violation of bunching between the undulator stages and a relatively high sensitivity of electron–photon interaction at wavelengths of higher harmonics to energy spread, size, deflection of the beam from the axis, etc. Expressions for the Bessel coefficients of the planar and elliptical undulators with field harmonics are analytically studied. Such undulators can be used in phase-shifted FELs for an increase in the power of higher (X-ray) harmonics by a factor of up to 100 in comparison with conventional FELs.

中文翻译：

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电子相对于光子相移的单程自由电子激光器中相干X射线谐波辐射的产生

摘要

从理论上研究了单通自由电子激光器（FEL）的聚束和谐波功率的演化，其中电子在具有磁场谐波的波荡器之间的间隔中相对于光子周期性地发生相移。分析计算用于揭示不对称椭圆形和平面波荡器的磁场结构，从而可以抑制基波并放大多个高次谐波。使用FEL的现象学模型分析了功率和聚束的演化，该模型描述了波动级之间的聚束的违反以及在较高谐波的波长下电子-光子相互作用对能量散布，尺寸，束从电子束偏转的相对较高的灵敏度。轴等 分析了带有场谐波的平面和椭圆波动器的贝塞尔系数的表达式。这种波动器可用于相移FEL中，与传统FEL相比，可将高（X射线）谐波的功率提高多达100倍。