• 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
  • show less
    Schematic of traditional γ-ray generation mechanisms at uniform plasma with different density (blue backgrounds represent plasma densities; black circles are electrons; purple represents the gamma photons; small red arrows show the moving direction of the electrons and gamma photons; light red arrows are the laser; and yellow arrows are the space charge force). (a) Low-density plasma nenc, forming a plasma channel. (b) Plasma density is close to the penetration threshold value nenth, showing the RESE process. (c) Transition region with nth<ne<nc* of the TOEE mechanism. (d) High density of ne>nc* of the SDE process.
    Fig. 1. Schematic of traditional γ-ray generation mechanisms at uniform plasma with different density (blue backgrounds represent plasma densities; black circles are electrons; purple represents the gamma photons; small red arrows show the moving direction of the electrons and gamma photons; light red arrows are the laser; and yellow arrows are the space charge force). (a) Low-density plasma nenc, forming a plasma channel. (b) Plasma density is close to the penetration threshold value nenth, showing the RESE process. (c) Transition region with nth<ne<nc* of the TOEE mechanism. (d) High density of ne>nc* of the SDE process.
    Schematic of the simulation setup and γ-ray generation mechanisms for a solid target with preplasma. Electrons are accelerated in the preplasma, and then interact with the reflected laser through the piled preplasma, emitting bright gamma radiation.
    Fig. 2. Schematic of the simulation setup and γ-ray generation mechanisms for a solid target with preplasma. Electrons are accelerated in the preplasma, and then interact with the reflected laser through the piled preplasma, emitting bright gamma radiation.
    Temporal evolution of electron numbers with at preplasma scale length of 0, 0.5λ, 2λ, and 4λ (the characteristic times of the maximum electron numbers are marked with arrows). The laser pulse profile at x = 18λ is also provided for the case of L = 0.
    Fig. 3. Temporal evolution of electron numbers with at preplasma scale length of 0, 0.5λ, 2λ, and 4λ (the characteristic times of the maximum electron numbers are marked with arrows). The laser pulse profile at x = 18λ is also provided for the case of L = 0.
    (a)–(d) Spatial density distributions of the electrons (black) and gamma photons (red) at corresponding characteristic times. (e)–(l) Phase space distribution of electron momentum (e)–(h) Px and (i)–(l) Py at the characteristic time. There are four cases: (a), (e), (i) L = 0; (b), (f), (j) L = 0.5λ (preplasma region 16–18 µm); (c), (g), (k) L = 2λ (10–18 µm); (d), (h), (l) L = 4λ (2–18 µm). The colorbars represent the electron density.
    Fig. 4. (a)–(d) Spatial density distributions of the electrons (black) and gamma photons (red) at corresponding characteristic times. (e)–(l) Phase space distribution of electron momentum (e)–(h) Px and (i)–(l) Py at the characteristic time. There are four cases: (a), (e), (i) L = 0; (b), (f), (j) L = 0.5λ (preplasma region 16–18 µm); (c), (g), (k) L = 2λ (10–18 µm); (d), (h), (l) L = 4λ (2–18 µm). The colorbars represent the electron density.
    The angular energy distributions of (a)–(d) energetic electrons and (e)–(h) and gamma photons at corresponding characteristic times (all units are MeV): (a), (e) L = 0; (b), (f) L = 0.5λ; (c), (g) L = 2λ; (d), (h) L = 4λ. The colorbars represent the lg N of electrons or gamma photons (N represents their density).
    Fig. 5. The angular energy distributions of (a)–(d) energetic electrons and (e)–(h) and gamma photons at corresponding characteristic times (all units are MeV): (a), (e) L = 0; (b), (f) L = 0.5λ; (c), (g) L = 2λ; (d), (h) L = 4λ. The colorbars represent the lg N of electrons or gamma photons (N represents their density).
    (a) The electron density (black to white colorbar) and laser field Ey (red to blue colorbar) distribution of the preplasma scale length L = 2 condition at characteristic time; (b) lineplot in the position of y = 5 µm for the laser field Ey, reflected laser field bp (bp = ), and electron density (blue is the current distribution and green is the initial profile).
    Fig. 6. (a) The electron density (black to white colorbar) and laser field Ey (red to blue colorbar) distribution of the preplasma scale length L = 2 condition at characteristic time; (b) lineplot in the position of y = 5 µm for the laser field Ey, reflected laser field bp (bp = ), and electron density (blue is the current distribution and green is the initial profile).
    The conversion efficiency of laser energy to (a) electrons and (b) γ-rays at various preplasma scale lengths.
    Fig. 7. The conversion efficiency of laser energy to (a) electrons and (b) γ-rays at various preplasma scale lengths.
    The conversion efficiency from laser energy to γ-rays at different scale lengths and laser parameters. The conversion efficiencies are saturated at longer scale lengths (d is the laser pulse width (FWHM) and T = 3.3 fs is the laser period for ).
    Fig. 8. The conversion efficiency from laser energy to γ-rays at different scale lengths and laser parameters. The conversion efficiencies are saturated at longer scale lengths (d is the laser pulse width (FWHM) and T = 3.3 fs is the laser period for ).
    Copy Citation Text
    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
    Download Citation
    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)