Speaker
Description
Studying the mechanisms of energetic α-particle slowing down, redistribution and the development of optimal plasma conditions for their confinement is a priority task for burning fusion reactors. The harsh radiation environment of deuterium-tritium (D-T) fusion reactors makes realisation of this task extremely difficult since a restricted set of plasma diagnostics will be available. In this presentation, we discuss various low-activation plasma scenarios and diagnostics for existing and forthcoming fusion machines that could allow α-particles study to be studied prior to reactor plasmas.
In JET, confined α-particles were studied in several low-activation plasma scenarios, generating 3.6-MeV alphas with the D(3He,p)4He fusion reaction, i.e. using the following ICRF plasma heating schemes: 1) 3He-minority ICRF heating of D-plasmas; 2) D-ion beam acceleration by 3rd harmonic ICRH and in the 3-ion ICRH scheme in D-3He plasmas. Also, confined MeV α-particles were studied in He-plasmas by accelerating the 4He-ion beam with 3rd harmonic ICRF and generating D-T α-particles with short T-NBI blips in deuterium plasmas. The confined α-particle diagnosis was based on detection of γ-rays from the nuclear reaction 9Be(α,nγ)12C [1].
In addition to the D(3He,p)4He reaction, there is another aneutronic fusion reaction, 11B(p,2α)4He, which also produces MeV α-particles and can be used for studies [2]. To generate highest density of α-particles with these fusion reactions, auxiliary heating with 3He-, D- and H-ions, as well as boron impurity are needed. Specifically, for α-particle studies we propose plasma heating scenarios with energetic hydrogen and deuterium neutral beam injection and ICRF heating.
Gamma-ray and neutron diagnostics, which are amongst a restricted set of reactor-compatible diagnostics, can be considered for confined α-particle measurements and characterisation of the fast H-, D- and 3He- ions in these low activation plasmas. For this purpose, nuclear reactions generating the required γ-rays and neutrons are selected [3]. Modelling and assessments of γ-ray and neutron diagnostic reactions show that a comprehensive study of α-particles could be performed in a currently working fusion devices, i.e. JT-60SA [4,5], prior to the operation of high-performance D-T plasmas.
- V.G. Kiptily, F.E. Cecil and S.S. Medley, 2006 Plasma Phys. Control. Fusion 48 R59
- K. Ogawa et al 2024 Nucl. Fusion 64 096028
- V.G. Kiptily et al 2026 Nucl. Fusion 66 066004
- Ye.O. Kazakov et al., 30th IAEA Fusion Energy Conference (2025)
- R. Coelho, see presentation at this meeting