Speaker
Description
Advanced instruments for fusion gamma-rays and alpha-particles monitoring of reactor plasmas
V.G. Kiptily on behalf of JET contributors and the EUROfusion Tokamak Exploitation Team
UKAEA, Culham Campus, Abingdon, Oxfordshire, OX14 3DB, United Kingdom
In fusion reactors with magnetic confinement the burning plasma control is strictly needed, i.e. the deuterium–tritium fuel ratio and temperature are among important parameters. Also, since the 3.5-MeV α-particles are a primary source of the plasma self-heating, they should be under continuous monitoring. However, a significant level of neutron and γ-ray fluxes requires to reduce the physical access to the plant that means some conventional diagnostics for the fusion plasma control will be unfeasible. Among the restricted set of instruments, which are available for the burning reactors, neutrons and γ-ray measurements will be demanded as the detectors can be placed far away from the plasma without a direct access to the vacuum vessel.
The recent full-scale D-T experiments (DTE2 and DTE3 campaigns in 2021 and 2023 accordingly) on JET a valuable experience of direct measurements of α-particles and fusion γ-rays has been obtained. These experiments confirm that a substantial development of dedicated instruments and methods are needed for the burning plasma reactor exploitation. Furthermore, understanding of a diagnostic-friendly reactor design is crystalised out.
In the talk the advanced burning plasma diagnostic instruments as well as their applications in reactors are presented. Using experience of γ-ray measurements in DTE2/3, a high-performance fusion γ-ray spectrometer, FUGAS, is under development for monitoring of the DT-fusion rate, plasma core temperature and fuel-ratio as well as the confined α-particles [1,2]. Alpha-particle measurements required a special diagnostic development. The confined α-particle measurements in DTE2/3 were based on detection of γ-rays from the beryllium nuclear reaction. For the non-beryllium fusion reactors alternative α-particle reactions are proposed, e.g. with boron [3]. The α-particle losses in JET were measured with an array of Faraday cups and the scintillator probe known as FILD. Considering the diagnostic benefits of these devices, an advanced concepts of the α-particle loss detector, SFILD and FILCA, are developed. These detectors could be used for α-particle loss measurements in the pre-burning phase of the reactor exploitation to optimise plasma scenarios. In the burning plasma phase, a remote technique of the α-particle loss monitoring, i.e. GRAM [4], with advanced γ-ray spectrometer FUGAS is proposed.
See the author list of C.F. Maggi et al 2024 Nucl. Fusion 64 112012
** See the author list of E. Joffrin et al 2024 Nucl. Fusion 64 112019
[1] Kiptily V.G. et al 2024 Nucl. Fusion 64 086059
[2] Kiptily V.G., 2015 Nucl. Fusion 55 023008
[3] Kiptily V,G., 2025 Fusion Eng. & Des. 215 114959
[4] Kiptily V.G. et al, 2018 Nucl. Fusion 58 082009
