Description
In the contribution we summarize the development and validation of an integrated modelling framework to study the interactions between energetic particles and metal wall impurities in tokamak plasmas. These reactions are expected to play an important role in providing early sources of energetic alpha particles in future fusion devices, and support nuclear diagnostics commissioning and synthetic diagnostics validation. In the presentation we detail JET-ILW experiments targeting sustained conditions in which fusion performance is driven by the interaction between fast protons and intrinsically present beryllium impurities. A steady-state L-mode plasma with dominant proton-beryllium fusion is developed in He and D. The fusion drive is unambiguously confirmed by multiple nuclear detectors, including a unique measurement of a dominant $^9$Be(p,$\alpha\gamma$)$^{6}$Li gamma peak. The experiment is analysed via a two-stage proton beryllium-fusion modelling chain, comprising TRANSP and JETTO for plasma core modelling, LOCUST for full orbit tracking, DRESS to resolve two- and three-body fusion kinematics, and MCNP for neutron transport calculations. Modelling shows that in these scenarios the primary $^9$Be(p,n)$^{9}$B reaction is the dominant neutron emitter at naturally present concentrations of beryllium, both in "aneutronic" He, and bulk D plasmas, validated against absolutely calibrated neutron yield measurements. We show that the proton-deuteron knock-on effect in D plasmas contributes significantly to the fusion yield. We additionally model reactions 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 $^{11}$B(p,$\alpha$)2$\alpha$, and detected via gammas emitted in secondary interactions between fast alphas and boron. The work represents an important step towards demonstrating and validating the capability to accurately model non-standard fusion reactions, providing high-fidelity input to energetic particle, MHD, turbulence, and neutronics codes.
This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion) and from the EPSRC [grant number EP/W006839/1]. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.