Chain-Enhanced α Yield in Proton-Driven p–¹¹B Fusion: Modeling, Optimization, and PIC Verification

Shih-Hung Chen^1*, Chih-Hao Pai¹, Chun-Han Chen¹, Shih Wei Wang¹, Yu-Hung Yeh¹

¹Department of Physics, National Central University, Zhongli, Taoyuan, Taiwan

* Presenter:Shih-Hung Chen, email:chensh@ncu.edu.tw

Deuterium–tritium (D–T) fusion yields high-energy neutrons that activate structural materials. Proton–boron (p–¹¹B) fusion is aneutronic and permits direct conversion of charged-particle kinetic energy to electricity [1–2]. However, thermal p-¹¹B reactivity is orders of magnitude below D–T when the plasma ion temperature at ~ 10 keV [3], and sustaining proton temperatures greater than 100 keV is impractical due to electron bremsstrahlung and synchrotron losses. For a boron-to-proton ratio of 0.089 and plasma density is 10²⁷ per cm³, laser-ignited thermal p-¹¹B requires plasma temperature ~ 140 keV and ion temperature ~280 keV with multi-MJ drivers [4], making conventional ICF unattractive.
This project targets non-thermal routes: direct irradiation of H–B targets and, primarily, pitcher–catcher schemes where laser-accelerated protons impinge on preheated boron [5]. Although measured α yields 10¹¹ per sr remain below ignition needs 10¹⁵ per sr [1], confining fusion-born α‘s and protons to drive chain reactions could materially raise α yield.
We will (i) design proton sources and spectra based on the CO₂-laser and the gas target; (ii) develop a zero-dimensional model including stopping-power effects to quantify chain feasibility and optimization of spectra/targets; and (iii) validate designs with particle-in-cell (PIC) simulations. The outcome will be actionable laser/target parameters and performance maps to advance chain-enhanced, aneutronic p-¹¹B fusion.

References
[1] Fabio Belloni, Laser and Particle Beams 2022, Article ID 3952779: https://doi.org/10.1155/2022/3952779.
[2] H. HORA et. al., Laser and Particle Beams 35, 730 (2017).
[3] S. Wurzel and S. Hsu, Phys. Plasmas 29, 062103 (2022).
[4] D. C. Moreau, Nuclear Fusion 17, 13 (1977).
[5] C. Labaune et. al., Nat. Commun. 4, 2506 (2013).

Keywords: proton-boron fusion, chain reaction, theoretical model, PIC simulation