High-Flux Neutron Generator Based on Laser-Driven Collisionless Shock Acceleration

Y. L. Yao, S. K. He, Z. Lei, T. Ye, Y. Xie, Z. G. Deng, B. Cui, W. Qi, L. Yang, S. P. Zhu, X. T. He, W. M. Zhou, and B. Qiao

Phys. Rev. Lett. 131, 025101 – Published 12 July 2023

Abstract

A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield $6.6 \times 10^{7} n / sr$ from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is $10^{19} W / {cm}^{2}$ . Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to $5 \times 10^{10} n / sr$ can be obtained when laser intensity increases to $10^{21} W / {cm}^{2}$ under the same laser energy.

Received 15 January 2022
Revised 20 October 2022
Accepted 24 May 2023

DOI:https://doi.org/10.1103/PhysRevLett.131.025101

Physics Subject Headings (PhySH)

High-energy-density plasmas Laser driven ion acceleration Laser-plasma interactions Neutron physics Nuclear reactions

Neutrons

Multiscale modeling Nuclear data analysis & compilation

Plasma PhysicsNuclear Physics

Authors & Affiliations

Y. L. Yao ^1,*, S. K. He ^2,*, Z. Lei^1,*, T. Ye³, Y. Xie ¹, Z. G. Deng², B. Cui ², W. Qi², L. Yang², S. P. Zhu³, X. T. He³, W. M. Zhou ^2,†, and B. Qiao ^1,4,‡

¹Center for Applied Physics and Technology, HEDPS and State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
²Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, China Academy of Engineering Physics (CAEP), Mianyang 621900, China
³Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
⁴Frontiers Science Center for Nano-optoelectronic, Peking University, Beijing 100094, China

^*These authors contributed equally to this work.
^†Corresponding author. zhouwm@caep.cn
^‡Corresponding author. bqiao@pku.edu.cn

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Issue

Vol. 131, Iss. 2 — 14 July 2023

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Images

Figure 1
Schematic view of the experiment. (a) Experimental setup. The pitcher target consists of two nanometer ${CD}_{2}$ foils perpendicular to each other, which are irradiated by, respectively, nanosecond and picosecond lasers (called “nanosecond foil” and “picosecond foil”), and the catcher LiF converter block is placed 10 cm away. Ions including both deuterons and protons are firstly accelerated by picosecond laser-driven CSA in the near-critical plasma (formed from expansions of both foils) and then are deposited into LiF converter for neutron production. (b) Diagnostics setup. A Thomson parabola (TP) spectrometer is placed 15 cm away (with solid angle $1.4 \times 10^{- 6} sr$ ) to detect the forward ion energy spectra. Three groups of bubble detectors (BDs) are placed at, respectively, 0° (14 cm away), 45° (10.3 cm), and 90° (17.5 cm) relative to the forward direction to measure the absolute neutron yields. Two liquid scintillation detectors (LSDs) are placed at 45° and 90° to measure the neutron energy spectra. The LSDs are shielded by a 20-cm-thick lead brick so that x rays are absorbed. The LSDs are calibrated with two energy points, 2.45 and 14.1 MeV, using a compact dense plasma focus neutron source and a 400 keV electrostatic accelerator neutron source [27].
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Figure 2
Experimental results. (a),(b) Raw image plate data of the on-axis Thomson parabola spectrometer for the cases with and without nanosecond laser ablation, respectively. (c) The corresponding ion energy spectra obtained from TP. (d) Neutron yields at 0°, 45°, and 90° for the cases with and without ablation. (e) The corresponding neutron energy spectra.
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Figure 3
Self-consistent simulation results. (a),(b) Density map at $t_{ns} = 3 ns$ and on-axis profiles at $t_{ns} = 2$ , 2.5, and 3 ns of the near-critical plasma obtained from 2D RMHD simulations with same $x$ axis, where $t_{ns}$ is the time after nanosecond laser has arrived at nanosecond foil. Picosecond foil is vertically located at $x = - 200 μ m$ and nanosecond foil is horizontally located at $y = 400 μ m$ . (c) Longitudinal profiles of the deuteron density (dashed lines) and the electrostatic field $E_{x}$ (solid lines) at $t = 1.05$ and 2.65 ps obtained from 2D PIC simulations, where $t_{ps}$ is the time after picosecond laser has arrived at picosecond foil. (d),(e) Phase space distributions $(x, p_{x})$ for, respectively, deuterons and protons at $t_{ps} = 2.5 ps$ for the CSA case obtained from 2D PIC simulations. (f) The corresponding final energy spectra of deuterons and protons obtained from 2D PIC simulations. (g) Angular distributions of the total neutron yield and its contributions, respectively, from $(d, x n)$ and $(p, x n)$ reactions obtained from 3D MC nuclear reaction simulations for the CSA case, in comparison with the experimental results as well as the TNSA cases. (h),(i) The corresponding energy spectra of neutrons at $θ = 0 °$ and $θ = 90 °$ , which have the same legends as those in (g).
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Figure 4
Simulation results for the proposed scheme with different laser parameters (intensities and pulse durations). (a) Energy spectra of the forward neutron flux at 0° and (b) forward neutron yield at 0°.
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