arXiv subjects

Xueqing Yan

Publications and source records attributed to Xueqing Yan.

41 records · Page 3Linked to original sources

arXiv2018

Brilliant GeV Gamma-ray flash from Inverse Compton Scattering in QED Regime

An all-optical scheme is proposed for studying a laser-plasma based incoherent photon emission from inverse Compton scattering in quantum electrodynamic (QED) regime. A theoretical model is presented to explain the coupling effect among radiation reaction trapping, self-generated magnetic field and spiral attractor in phase space, which guarantees the energy and angular momentum (AM) transformation from electromagnetic fields to particles. Taking advantage of a prospective $\sim$10$^{23}$W/cm$^{2}$ laser facility, 3D Particle-in-cell (PIC) simulations manifest the present gamma-ray flash with an unprecedented power of multi-petawatt (PW) and brightness of 1.7$\times$10$^{23}$photons/s/mm$^2$/mrad$^2$/0.1$\%$bandwidth (at 1GeV). These results bode well for new research direction in particle physics and laboratory astrophysics while exploring laser plasma interaction.

physics.plasm-ph↗

arXiv2017

Electron dynamics and injection in plasma-based accelerators with sharp vacuum-plasma transitions

The dynamic process of a laser or particle beam propagating from vacuum into underdense plasma has been investigated theoretically. Our theoretical model combines a Lagrangian fluid model with the classic quasistatic wakefield theory. It is found that background electrons can be injected into wakefields because sharp vacuum-plasma transitions can reduce the injection threshold. The injection condition, injection threshold as well as the injection length can be given theoretically by our model and are compared with results from computer simulations. Moreover, electron beams of high qualities can be produced near the injection thresholds and the proposed scheme is promising in reducing the injection threshold and improving the beam qualities of plasma based accelerators.

physics.plasm-ph↗

arXiv2017

Ultra-brilliance isolated attosecond gamma-ray light source from nonlinear Compton scattering

The explosion in attosecond technology has opened the gate to investigating many unexplored areas which require ultrahigh spatial and temporal resolution. In the area of nuclear physics, using gamma-rays with ultrahigh resolution in time and space will help to investigate intra-nuclear dynamics in an unprecedentedly explicit way. However, the generation of ultrahigh brilliance attosecond gamma-ray pulses with current-generation laser facilities has not been reported. In this letter, we propose a novel method to generate high charge (~1nC) attosecond (<200 attosecond) electron bunch by the near-threshold self-injection in a wakefield accelerator. We demonstrate the ability to generate an ultrahigh-brilliance (> 2*1024 photons s-1mm-2mrad-2 per 0.1%BW) attosecond (<200 attosecond) gamma-ray (Emax > 3 MeV) pulse via nonlinear Compton scattering. To the best of our knowledge, this is the first method reported to generate attosecond gamma-ray photon source using current-generation laser. This is the shortest gamma-ray photon and the highest brilliance photon source in MeV range (orders higher than the results reported). This method can be widely applied for experimental generation of 100 keV to several MeV high brilliance attosecond gamma-ray sources with current ~100 TW laser facilities, which will benefit basic science such as application in ultra-high resolution radiography.

physics.plasm-ph↗

arXiv2015

Reduce proton energy spread by target ablation

It's shown that, with strong target ablation monoenergetic protons along the laser direction is available during the laser aluminum foil interaction, which is different from the classic TNSA theory. When the laser pre-pulse is too strong that the whole target is vaporized, the energetic electrons generated in the gas preplasma will play an important role for the ion acceleration because the sheath field will not be available. These electrons beam, which is highly directional, will setup triangle envelope acceleration field along the laser direction at the target rear, reducing the ion energy spread.

physics.plasm-ph↗

arXiv2010

Beam optimization of RFQ and SFRFQ combined accelerator at Peking University

The Peking University Integral Split Ring Radio Frequency Quadrupole(ISR RFQ) accelerator was constructed in 1999 with a high duty factor 16.7% and repetition frequency 166Hz, and it was able to accelerate N+, O+,O-, C+ and He+ from 1.6kev/u to 65keV/u. It was later upgraded as an injector of the Separated Function RFQ (SFRFQ). The experiments indicated that the maximum accelerated O+ beam current could exceed 3.2mA with energy 1.03MeV and an energy spread (FWHM) 3.1%. Then the beam transports through a 1m-long magnetic triplet to the entrance of SFRFQ and is finally accelerated to 1.64MeV. The beam conditioning of RFQ were carefully optimized to satisfy the requirements of the SFRFQ. The combined accelerator eventually can deliver 0.53mA O+ beam with energy 1.65MeV, which has sufficiently demonstrated the feasibility of the SFRFQ structure.

physics.acc-ph↗