• High Power Laser Science and Engineering
  • Vol. 8, Issue 4, 04000e34 (2020)
Xiang-Bing Wang1、2, Guang-Yue Hu1、3、*, Zhi-Meng Zhang2, Yu-Qiu Gu2、4, Bin Zhao1, Yang Zuo1, and Jian Zheng1、4
Author Affiliations
  • 1CAS Key Laboratory of Geospace Environment and Department of Engineering and Applied Physics, University of Science and Technology of China, Hefei230026, China
  • 2Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang621900, China
  • 3CAS Center for Excellence in Ultra-intense Laser Science (CEULS), Shanghai200031, China
  • 4IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai200240, China
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    In the laser plasma interaction of quantum electrodynamics (QED)-dominated regime, γ-rays are generated due to synchrotron radiation from high-energy electrons traveling in a strong background electromagnetic field. With the aid of 2D particle-in-cell code including QED physics, we investigate the preplasma effect on the γ-ray generation during the interaction between an ultraintense laser pulse and solid targets. We found that with the increasing preplasma scale length, the γ-ray emission is enhanced significantly and finally reaches a steady state. Meanwhile, the γ-ray beam becomes collimated. This shows that, in some cases, the preplasmas will be piled up acting as a plasma mirror in the underdense preplasma region, where the γ-rays are produced by the collision between the forward electrons and the reflected laser fields from the piled plasma. The piled plasma plays the same role as the usual reflection mirror made from a solid target. Thus, a single solid target with proper scale length preplasma can serve as a manufactural and robust γ-ray source.

    1 Introduction

    Preplasma has an important effect on the interaction between laser and matter, especially in solid targets, which produces different laser absorption mechanisms in sub-relativistic laser states, such as resonance absorption[1] and vacuum heating (the Brunel mechanism)[2]. Based on these studies, several interesting results have been obtained recently, such as the Brunel-like mechanism[3], high harmonic generation[4], and vacuum electron acceleration[5]. With the gargantuan laser powers projected to be realized in the developing petawatt (PW) facilities ELI in Europe[69] and SULF in China[10], the interaction between lasers and plasmas is poised to occur in the ultrarelativistic state[11]. As is commonly understood, in the quantum electrodynamics (QED)-dominated regime, when an ultraintense laser interacts with a target, γ-rays can be generated by synchrotron radiation arising from high-energy electrons traveling in a strong, background electromagnetic field[12,13]. Previous studies focused on the function of the preplasma before a dense target[14,15], scanning different parameters to obtain the optimal γ-ray source. The other efficient method to generate γ-ray flare is to make accelerated electrons interact with a reflected laser, a method called all-optical Compton backscattering, in which electrons may be accelerated by a wakefield[16,17] or pondermotive force[18] and laser is reflected by a dense plasma mirror. In these cases, underdense gas or nanoparticles[19] are required before the solid targets in their plans. The γ-rays generated in different regimes have lent themselves to many applications, such as dense matter tomography[20], photonuclear reactions[21], and laboratory astrophysics[22]. Previous research has shown that an ultraintense laser interacting with a plasma can emit γ-rays in different directions, depending on the plasma density[11,12,23] and the corresponding physical mechanisms at play.

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    Xiang-Bing Wang, Guang-Yue Hu, Zhi-Meng Zhang, Yu-Qiu Gu, Bin Zhao, Yang Zuo, Jian Zheng. Gamma-ray generation from ultraintense laser-irradiated solid targets with preplasma[J]. High Power Laser Science and Engineering, 2020, 8(4): 04000e34
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    Category: Research Articles
    Received: May. 9, 2020
    Accepted: Aug. 4, 2020
    Posted: Aug. 5, 2020
    Published Online: Oct. 16, 2020
    The Author Email: Guang-Yue Hu (gyhu@ustc.edu.cn)