Plasma and Fusion Research

Volume 21, 1405028 (2026)

Regular Articles

Numerical Study of Proton Impact Rates on a Solid Target in Pyroelectric Fusion: Effects of Electrode Geometry and Crystal Heating Temperature
Shun INOUE1), Toru TAKAHASHI1), Siyu ZHANG1), Toshiki TAKAHASHI1), Masahiko SATO2)
1)
Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
2)
National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
(Received 25 December 2025 / Accepted 15 February 2026 / Published 4 June 2026)

Abstract

Numerical simulations were conducted for a pyroelectric fusion device with three electrode geometries to investigate proton generation, acceleration, and impact with a solid 11B target. Evaluation of the electric field distributions showed that the maximum potential scales with the crystal temperature difference as ϕmax ≃ 238 ΔT [kV]. Analysis of electron-impact ionization clarified the spatial regions where protons are generated and begin to accelerate, revealing that a considerable fraction of protons is laterally deflected by the electric field structure and fail to reach the target. The proton impact rate was systematically examined by varying the electrode geometry and heating conditions. The results indicate that the impact rate is maximized at moderate temperature differences, whereas excessively strong electric fields shift the ionization region outward and reduce proton delivery to the target. Further analysis suggests that rapid electron acceleration near the electrode shortens the residence time within the energy range favorable for ionization, thereby suppressing proton generation under high heating conditions. These results demonstrate that proton impact efficiency in pyroelectric fusion devices is strongly governed by the interplay between electrode geometry, ionization location, and operating temperature. Appropriate control of these parameters is therefore essential for improving target-directed proton irradiation.

Keywords

pyroelectric fusion, proton-boron fusion, beam current, numerical analyses

DOI: 10.1585/pfr.21.1405028

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