Attosecond Polarisation Modulation of X-ray Radiation in a Free Electron Laser

轨道控制的双色阿秒模式锁自由电子激光生成

Orbit-Controlled Generation of Two-color Attosecond Mode-locked Free-electron Lasers

本文提出通过轨道控制在双阶段模式锁wiggler中生成双色阿秒模式锁自由电子激光脉冲的方法，实现了高能和低能电子束分别产生阿秒脉冲并调节时间延迟。

高功率阿秒X射线自由电子激光：物理与设计策略

High-power attosecond X-ray free-electron lasers: physics and design strategy

研究高功率阿秒X射线自由电子激光的物理机制与设计方法，探讨电子束特性对性能的影响，提供优化指南。

SASE FEL with energy-chirped electron beam and its application for generation of attosecond pulses

Influence of a linear energy chirp in the electron beam on a SASE FEL operation is studied analytically and numerically using 1-D model. Explicit expressions for Green's functions and for output power of a SASE FEL are obtained for high-gain linear regime in the limits of small and large energy chirp parameter. Saturation length and power versus energy chirp parameter are calculated numerically. It is shown that the effect of linear energy chirp on FEL gain is equivalent to the linear undulator tapering (or linear energy variation along the undulator). A consequence of this fact is a possibili…

A new technique to generate 100 GW-level attosecond X-ray pulses from the X-ray SASE FELs

We propose a scheme for generation of single 100 GW 300-as pulse in the X-ray free electron laser with the use of a few cycles optical pulse from Ti:sapphire laser system. Femtosecond optical pulse interacts with the electron beam in the two-period undulator resonant to 800 nm wavelength and produces energy modulation within a slice of the electron bunch. Following the energy modulator the electron beam enters the first part of the baseline gap-adjustable X-ray undulator and produces SASE radiation with 100 MW-level power. Due to energy modulation the frequency is correlated to the longitudina…

Generation of Coherent X-Ray Radiation Through Modulation Compression

In this paper, we propose a scheme to generate tunable coherent X-ray radiation for future light source applications. This scheme uses an energy chirped electron beam, a laser modulator, a laser chirper and two bunch compressors to generate a prebunched kilo-Ampere current electron beam from a few tens Ampere electron beam out of a linac. The initial modulation energy wavelength can be compressed by a factor of $1+h_b R_{56}^a$ in phase space, where $h_b$ is the energy bunch length chirp introduced by the laser chirper, $R_{56}^a$ is the momentum compaction factor of the first bunch compressor…

少粒子光电子脉冲中的飞秒与阿秒相空间关联

Femtosecond and attosecond phase-space correlations in few-particle photoelectron pulses

本文结合飞秒门控事件探测与非弹性电子–光散射，直接测量双电子态相空间分布，并理论证明全局相位调制可形成阿秒时间关联。

MeV femtosecond electron pulses from direct-field acceleration in low density atomic gases

Using three-dimensional particle-in-cell simulations, we show that few-MeV electrons can be produced by focusing tightly few-cycle radially-polarized laser pulses in a low-density atomic gas. In particular, it is observed that for the few-TW laser power needed to reach relativistic electron energies, longitudinal attosecond microbunching occurs naturally, resulting in femtosecond structures with high-contrast attosecond density modulations. The three-dimensional particle-in-cell simulations show that in the relativistic regime the leading pulse of these attosecond substructures survives to pro…

相稳定自调制用于GHz连续波超快X射线自由电子激光

Phase-Stable Self-Modulation for GHz Continuous-Wave Ultrafast X-Ray Free-Electron Lasers

本文提出一种无需激光的方案，通过连续相稳定自调制过程克服高重复率XFEL中的峰值电流限制，实现高重复率下的超短X射线脉冲生成。

Using the longitudinal space charge instability for generation of VUV and X-ray radiation

Longitudinal space charge (LSC) driven microbunching instability in electron beam formation systems of X-ray FELs is a recently discovered effect hampering beam instrumentation and FEL operation. The instability was observed in different facilities in infrared and visible wavelength ranges. In this paper we propose to use such an instability for generation of VUV and X-ray radiation. A typical longitudinal space charge amplifier (LSCA) consists of few amplification cascades (drift space plus chicane) with a short undulator behind the last cascade. If the amplifier starts up from the shot noise…

通过受激近场相互作用合成自由电子波函数

Synthesizing free-electron wave functions by stimulated near-field interactions

本研究通过受激近场相互作用合成自由电子波函数，提出分阶段控制方法，在10 keV SEM配置下实现优于先前20%的压缩效果，并利用路径信息调控密度与相干性。

共振射频腔体耦合用于混合激光等离子体加速器中三维betatron动力学的辐射反应控制

Resonant RF Wakefield Coupling for Radiation-Reaction Control of 3D Betatron Dynamics in Hybrid Laser Plasma Accelerators

本文研究了混合激光等离子体加速器中通过共振射频腔体耦合控制三维betatron动力学的辐射反应问题，结合分析模型和PIC模拟，揭示了射频场与自然betatron频率的共振机制及其对束流稳定性的影响。

Controlling free electrons with optical whispering-gallery modes

Free-electron beams serve as uniquely versatile probes of microscopic structure and composition, and have repeatedly revolutionized atomic-scale imaging, from solid-state physics to structural biology. Over the past decade, the manipulation and interaction of electrons with optical fields has seen significant progress, enabling novel imaging methods, schemes of near-field electron acceleration, and culminating in 4D microscopy techniques with both high temporal and spatial resolution. However, weak coupling strengths of electron beams to optical excitations are a standing issue for existing an…