Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET

0538148 - ÚFP 2021 RIV AT eng J - Článek v odborném periodiku
Casson, F.J. - Patten, H. - Bourdelle, C. - Breton, S. - Citrin, D. S. - Koechl, F. - Sertoli, M. - Angioni, C. - Baranov, Y. - Bilato, R. - Belli, E.A. - Challis, C.D. - Corrigan, G. - Czarnecka, A. - Ficker, Ondřej - Frassinetti, L. - Garzotti, L. - Goniche, M. - Graves, J.P. - Johnson, T. - Kirov, K. - Knight, P. - Lerche, E. - Mantsinen, M. - Mlynář, Jan - Valisa, M.
Predictive multi-channel flux-driven modelling to optimise ICRH tungsten control and fusion performance in JET.
Nuclear Fusion. Roč. 60, č. 6 (2020), č. článku 066029. ISSN 0029-5515. E-ISSN 1741-4326
GRANT EU: European Commission(XE) 633053 - EUROfusion
Klíčová slova: DT extrapolation * icrh * impurity transport * integrated modeling * isotope scaling * jet * tungsten
Obor OECD: Fluids and plasma physics (including surface physics)
Impakt faktor: 3.179, rok: 2020
Způsob publikování: Open access
https://iopscience.iop.org/article/10.1088/1741-4326/ab833f

The evolution of the JET high performance hybrid scenario, including central accumulation of the tungsten (W) impurity, is reproduced with predictive multi-channel integrated modelling over multiple confinement times using first-principle based core transport models. Eight transport channels (Ti, Te, j, nD, nBe, nNi, nw, ω) are modelled predictively, with self-consistent sources, radiation and magnetic equilibrium, yielding a system with multiple non-linearities: This system can reproduce the observed radiative temperature collapse after several confinement times. W is transported inward by neoclassical convection driven by the main ion density gradients and enhanced by poloidal asymmetries due to centrifugal acceleration. The slow evolution of the bulk density profile sets the timescale for W accumulation. Modelling this phenomenon requires a turbulent transport model capable of accurately predicting particle and momentum transport (QuaLiKiz) and a neoclassical transport model including the effects of poloidal asymmetries (NEO) coupled to an integrated plasma simulator (JINTRAC). The modelling capability is applied to optimise the available actuators to prevent W accumulation, and to extrapolate in power and pulse length. Central NBI heating is preferred for high performance, but gives central deposition of particles and torque which increase the risk of W accumulation by increasing density peaking and poloidal asymmetry. The primary mechanism for ICRH to control W in JET is via its impact through turbulence in reducing main ion density peaking (which drives inward neoclassical convection), increased temperature screening and turbulent W diffusion. The anisotropy from ICRH also reduces poloidal asymmetry, but this effect is negligible in high rotation JET discharges. High power ICRH near the axis can sensitively mitigate against W accumulation, and dominant ion heating (e.g. He-3 minority) is predicted to provide more resilience to W accumulation than dominant electron heating (e.g. H minority) in the JET hybrid scenario. Extrapolation to DT plasmas finds 17.5 MW of fusion power and improved confinement compared to DD, due to reduced ion-electron energy exchange, and increased Ti/Te stabilisation of ITG instabilities. The turbulence reduction in DT increases density peaking and accelerates the arrival of W on axis - this may be mitigated by reducing the penetration of the beam particle source with an increased pedestal density.
Trvalý link: http://hdl.handle.net/11104/0315970