TY - JOUR
T1 - Experimental observation and integrated modelling of proton-beryllium fusion in He and D plasmas at JET
AU - Štancar,
AU - Eriksson, J.
AU - Oliver, H. J.C.
AU - Kiptily, V. G.
AU - Conroy, S.
AU - Čufar, A.
AU - Hjalmarsson, A.
AU - Kazakov, Ye O.
AU - Ghani, Z.
AU - Gorelenkova, M.
AU - Boboc, A.
AU - Carvalho, P.
AU - Chomiczewska, A.
AU - Delabie, E.
AU - Dreval, M.
AU - Garzotti, L.
AU - Kirov, K. K.
AU - Kos, D.
AU - Lawson, K. D.
AU - Lengar, I.
AU - Lennholm, M.
AU - Lerche, E.
AU - Litaudon, X.
AU - Litherland-Smith, E.
AU - Maslov, M.
AU - Menmuir, S.
AU - O’Mullane, M.
AU - Parr, E.
AU - Patel, A.
AU - Snoj, L.
AU - Sydenham, R.
AU - Sun, H. J.
AU - Villari, R.
AU - Wang, V. T.
AU - Zotta, V. K.
AU - JET Contributors
N1 - Publisher Copyright:
© 2026 Crown copyright, UK Atomic Energy Authority & The Author(s). Published by IOP Publishing Ltd on behalf of the IAEA. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
PY - 2026/9
Y1 - 2026/9
N2 - Validated integrated modelling of JET ITER-like wall experiments in which fusion performance is driven by reactions between fast ions and intrinsically present metal wall impurities is presented. A steady-state L-mode plasma with dominant proton-beryllium fusion and neutron yields of up to (Formula presented) (Formula presented) 6 (Formula presented) (Formula presented) 10 (Formula presented) (Formula presented) is developed in He and D, via radiofrequency heating of a H minority. The fusion drive is unambiguously confirmed by the neutral particle analyser, fast ion loss detector, and (Formula presented) (Formula presented) -ray diagnostics. Experiments are analysed via an integrated modelling framework, developed to model the two-stage proton beryllium-fusion chain and produce high-fidelity fusion product source terms. The modelling chain comprises TRANSP and JETTO for plasma core modelling, LOCUST for full orbit product tracking and collisional slowing-down, DRESS to resolve two- and three-body fusion kinematics, and MCNP for neutron transport calculations. Modelling shows that the primary (Formula presented) (Formula presented) Be(p,n) (Formula presented) (Formula presented) B reaction is the dominant neutron emitter at naturally present concentrations of beryllium in these experiments. The yield contribution of secondary reactions between fusion products and beryllium, (Formula presented) (Formula presented) Be(d,n) (Formula presented) (Formula presented) B and (Formula presented) (Formula presented) Be( (Formula presented) (Formula presented) ,n) (Formula presented) (Formula presented) C, is found to be negligible. The proton-deuteron knock-on effect in D plasmas is modelled, which is calculated to contribute (Formula presented) (Formula presented) 25% to the total neutron yield. For both He and D discharges the total computed neutron rates match fission chamber (FC) measurements within the combined experimental and computational uncertainty, with an average discrepancy of (Formula presented) (Formula presented) 20%. Realistic proton-beryllium neutron sources are propagated through JET’s MCNP neutron transport model which shows that (Formula presented) (Formula presented) U FCs’ response is sensitive to p–Be source changes, with up to (Formula presented) (Formula presented) 10% variation compared to a D–D neutron source. We show that the high-energy tail of the fast proton minority can be studied with multi-foil neutron activation. The framework is also applied to the study of interactions between fast protons and boron impurities, of relevance to ITER. We calculate that in JET conditions a significant alpha source with DT-like energies could be generated through (Formula presented) (Formula presented) B(p, (Formula presented) (Formula presented) )2 (Formula presented) (Formula presented) fusion, and detected via (Formula presented) (Formula presented) -emission in secondary interactions between fast alphas and boron. The work represents an important step towards validating predictive integrated modelling capabilities for non-standard fusion reactions.
AB - Validated integrated modelling of JET ITER-like wall experiments in which fusion performance is driven by reactions between fast ions and intrinsically present metal wall impurities is presented. A steady-state L-mode plasma with dominant proton-beryllium fusion and neutron yields of up to (Formula presented) (Formula presented) 6 (Formula presented) (Formula presented) 10 (Formula presented) (Formula presented) is developed in He and D, via radiofrequency heating of a H minority. The fusion drive is unambiguously confirmed by the neutral particle analyser, fast ion loss detector, and (Formula presented) (Formula presented) -ray diagnostics. Experiments are analysed via an integrated modelling framework, developed to model the two-stage proton beryllium-fusion chain and produce high-fidelity fusion product source terms. The modelling chain comprises TRANSP and JETTO for plasma core modelling, LOCUST for full orbit product tracking and collisional slowing-down, DRESS to resolve two- and three-body fusion kinematics, and MCNP for neutron transport calculations. Modelling shows that the primary (Formula presented) (Formula presented) Be(p,n) (Formula presented) (Formula presented) B reaction is the dominant neutron emitter at naturally present concentrations of beryllium in these experiments. The yield contribution of secondary reactions between fusion products and beryllium, (Formula presented) (Formula presented) Be(d,n) (Formula presented) (Formula presented) B and (Formula presented) (Formula presented) Be( (Formula presented) (Formula presented) ,n) (Formula presented) (Formula presented) C, is found to be negligible. The proton-deuteron knock-on effect in D plasmas is modelled, which is calculated to contribute (Formula presented) (Formula presented) 25% to the total neutron yield. For both He and D discharges the total computed neutron rates match fission chamber (FC) measurements within the combined experimental and computational uncertainty, with an average discrepancy of (Formula presented) (Formula presented) 20%. Realistic proton-beryllium neutron sources are propagated through JET’s MCNP neutron transport model which shows that (Formula presented) (Formula presented) U FCs’ response is sensitive to p–Be source changes, with up to (Formula presented) (Formula presented) 10% variation compared to a D–D neutron source. We show that the high-energy tail of the fast proton minority can be studied with multi-foil neutron activation. The framework is also applied to the study of interactions between fast protons and boron impurities, of relevance to ITER. We calculate that in JET conditions a significant alpha source with DT-like energies could be generated through (Formula presented) (Formula presented) B(p, (Formula presented) (Formula presented) )2 (Formula presented) (Formula presented) fusion, and detected via (Formula presented) (Formula presented) -emission in secondary interactions between fast alphas and boron. The work represents an important step towards validating predictive integrated modelling capabilities for non-standard fusion reactions.
KW - JET
KW - integrated modelling
KW - neutron yield
KW - plasma neutron source
KW - proton-beryllium fusion
UR - https://www.scopus.com/pages/publications/105045957089
U2 - 10.1088/1741-4326/ae870b
DO - 10.1088/1741-4326/ae870b
M3 - Article
AN - SCOPUS:105045957089
SN - 0029-5515
VL - 66
JO - Nuclear Fusion
JF - Nuclear Fusion
IS - 9
M1 - 096005
ER -