Matter and Radiation at Extremes, Volume. 9, Issue 5, 057202(2024)
Compact ultrafast neutron sources via bulk acceleration of deuteron ions in an optical trap
Fig. 1. Schematic of neutron source from an optical trap (OT). (a) Two lasers with the same frequency, sub-picosecond duration, and moderate intensity first overlap inside the near-critical density plasma. These are termed OT pulses. Then, a laser pulse with relativistic high intensity (boost pulse) is injected after certain time delay for ion energy boosting. (b) Closeup of adjacent plasma gratings outlined by the black rectangle in (a), corresponding to pre-acceleration of ions in the OT. As the density grating grows, the thermal pressure expels electrons, which results in the generation of an electric field that reflects the ions. (c) Neutron generation triggered by colliding ions after energy boosting.
Fig. 2. Evolution of an OT and self-generated electric fields. (a) Time–space evolution of electrostatic fields in an OT, where a closeup of only three periodic layers is shown.
Fig. 3. Ion phase space and longitudinal electrostatic fields along the laser axis (white dashed line) from 2D simulation. The top plot is at 640 fs, before the two boost lasers arrive. The middle plot is at 1.06 ps, without boost laser injection. The bottom plot is at 780 fs, with the boost lasers.
Fig. 4. Boosted ion energy features according to 2D PIC simulations. (a) Ion energy angular distribution. (b) Ion energy spectrum at two emission angles: 0° (red full line) and 90° (blue dashed line).
Fig. 5. (a) and (b) 1D simulation results for deuteron phase space and density distributions at 820 and 860 fs, respectively, with energy boosted by boost lasers.
Fig. 6. Boosted ion velocity as a function of four different parameters, namely, the time delay of the boost lasers, the initial plasma density, the boost laser intensity, and the OT laser wavelength, obtained from the simulation and the toy model. (a) Dependence of the velocity (blue line with solid circles) and OT density (red dashed line with triangles) on the time difference between OT and boost lasers from the simulation, together with the velocity as estimated by the toy model (black open squares). The blue open circle is the simulation result without the boost laser. (b) Dependence of the velocity (blue line with solid circles) and layer distance (red dashed line with triangles) on the initial plasma density, together with the velocity as estimated by the toy model (black open squares). (c) Dependence of the velocity on the boost laser strength (upper plot) and on the OT laser wavelength (bottom plot), with fixed
Fig. 7. Neutron production results in OT via bulk acceleration, given by 1D3V simulations. (a) Temporal evolution of the neutron production rate
Fig. 8. The upper plot shows the central energy value of neutron spectra at different emission angles, and the lower plot the spectral ranges (blue) with the corresponding peak neutron production values (red).
Fig. 9. Neutron production results from 2D PIC simulations. (a) Spatial distribution of volumetric neutron production rate
Fig. 10. Results for the proposed scheme with different OT laser wavelength
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Zhiyu Lei, Hanghang Ma, Xiaobo Zhang, Lin Yu, Yihang Zhang, Yutong Li, Suming Weng, Min Chen, Jie Zhang, Zhengming Sheng. Compact ultrafast neutron sources via bulk acceleration of deuteron ions in an optical trap[J]. Matter and Radiation at Extremes, 2024, 9(5): 057202
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Received: Mar. 18, 2024
Accepted: Jun. 10, 2024
Published Online: Oct. 14, 2024
The Author Email: Sheng Zhengming (zmsheng@sjtu.edu.cn)