arXiv subjects

Yuekai Chen

Publications and source records attributed to Yuekai Chen.

3 recordsLinked to original sources

arXiv2026

Effects of realistic laser intensity and phase distribution on high-charge laser wakefield acceleration

Laser wakefield acceleration (LWFA) can produce relativistic electron beams and various secondary particles in centimeter-long plasmas, making it a valuable particle source with important applications in many disciplines. In this work, we examine the effects of non-ideal transverse intensity and phase distribution of laser pulses on LWFA through both experimental measurements and particle-in-cell simulations. The complex transverse profile of the 75 TW laser pulses reduces the self-focused intensity in plasma compared with a transversely Gaussian laser. Furthermore, the sheath structure of the nonlinear plasma wake excited by realistic laser pulses is wider and more complicated than that of a Gaussian laser. These hinder the injection of the plasma electrons. As the laser pulse propagates through the plasma, its intensity profile gradually becomes elliptical and drives a plasma wake with a sharp sheath near the azimuths of the major axis, leading to an injection. When using a realistic laser profile in simulations, both the charge and energy of injected electrons closely match experimental results ($\sim200$ pC of charge and $\sim 200$ MeV peak energy), whereas the Gaussian laser simulations produce much higher charge ($\sim500$ pC). Our findings reveal the difference in injection dynamics between LWFA driven by non-ideal laser pulses and those driven by Gaussian pulses, and are useful for applications of LWFA which demand high-charge electron beams.

physics.plasm-ph↗

arXiv2025

Generating 10 GW-class isolated zeptosecond x-ray bursts through bootstrapping two plasma-based accelerator stages

A method is proposed to generate coherent, intense zeptosecond x-ray pulses by using the electron beam produced by a laser wakefield accelerator (LWFA) stage as the driver for a beam driven plasma wakefield accelerator (PWFA) stage. The LWFA injector stage requires a readily available 100 TW laser driver to produce a GeV class self-injected electron beam. This beam is focused and used as the driver in a PWFA stage that utilizes a solid-density plasma with a modulated density downramp. The concept is shown to be capable of producing an ultra-short electron beam with unprecedented density ($10^{26}~\mathrm{cm^{-3}}$) and brightness ($ 10^{24}~\ampere/\meter^2/\radian ^2$), that is also pre-bunched on 0.1 Angstrom scales. By colliding this pre-bunched extreme beam with an optical undulator, an intense zeptosecond pulse can be emitted if the spatially focusing region is matched with the lasing region of the beam. Multi-dimensional particle-in-cell simulations are performed of the entire concept to demonstrate that an isolated 10 GW-class zeptosecond pulse with a full-width-half-maximum duration of 700 zs can be generated in a tapered laser pulse. Such an intense zeptosecond pulse generation scheme may provide an essential probe for nuclear physics and quantum electrodynamics processes.

physics.acc-ph↗

arXiv2023

On the generation of attosecond gigawatt soft X-ray pulses through coherent Thomson backscattering

Collision between relativistic electron sheets and counter-propagating laser pulses is recognized as a promising way to produce intense attosecond X-rays through coherent Thomson backscattering (TBS). In a double-layer scheme, the electrons in an ultrathin solid foil are first pushed out by an intense laser driver and then interact with the laser reflected off a second foil to form a high-density relativistic electron sheet with vanishing transverse momentum. However, the repulsion between these concentrated electrons can increase the thickness of the layer, reducing both its density and subsequently the coherent TBS. Here, we present a systematic study on the evolution of the flying electron layer and find that its resulting thickness is determined by the interplay between the intrinsic space-charge expansion and the velocity compression induced by the drive laser. How the laser driver, the target areal density, the reflector and the collision laser intensity affect the properties of the produced X-rays is explored. Multi-dimensional particle-in-cell simulations indicate that employing this scheme in the nonlinear regime has the potential to stably produce soft X-rays with several GW peak power in hundreds of TW ultrafast laser facilities. The pulse duration can be tuned to tens of attoseconds. This compact and intense attosecond X-ray source may have broad applications in attosecond science.

physics.plasm-ph↗