Modelling of charge-exchange induced NBI losses in the COMPASS upgrade tokamak

Nuclear Fushion

article

F. Jaulmes¹  G. Zadvitskiy¹  K. Bogar¹  M. Imrisek¹  J. Hromadka¹  S.Y. Cats²  J. Varju¹  M. Komm¹  R. Panek¹ 

[1] Institute of Plasma Physics of the CAS;FOM Institute DIFFER

关键词: NBI;    fast ions;    charge-exchange;    toroidal field ripple;    full-orbit code;    Coulombcollisions;    COMPASS-upgrade;   

DOI  :  10.1088/1741-4326/abd41b

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

The COMPASS upgrade tokamak (Paneket al2017Fusion Eng. Des.12311–16) will be a tokamak of major radiusR ₀ = 0.894 m with the possibility to reach high field ( B _t ∼ 5 T) and high current ( I _p ∼ 2 MA). The machine should see its first plasma in 2023 and H-mode plasma will be obtained from 2025. The main auxiliary heating system used to access H-mode will be 4 MW of neutral beam injection (NBI) power. The NBI will have a nominal injection energy of 80 keV, a maximum injection radiusR _tan = 0.65 m and will create a population of well-confined energetic D ions. In this contribution, our modelling studies the NBI deposition and losses when a significant edge background density of neutrals is assumed. We follow the fast ions in the 3D field generated by the 16 toroidal field (TF) coils using the upgraded EBdyna orbit solver (Jaulmeset al2014Nucl. Fusion54104013). We have implemented a Coulomb collision operator similar to that of NUBEAM (Goldstonet al1981J. Comput. Phys.4361) and a charge-exchange operator that follows neutrals and allows for multiple re-ionizations. Detailed integrated modelling with the METIS code (Artaudet al2018Nucl. Fusion58105001) yields the pressure and current profiles for various sets of achievable engineering parameters. The FIESTA code (Cunningham 2013Fusion Eng. Des.883238–3247) calculates the equilibrium and a Biot–Savart solver is used to calculate the intensity of the perturbation induced by the TF coils. Initial distributions of the NBI born fast ions are obtained from the newly developed NUR code, based on Suzukiet al(1998Plasma Phys. Control. Fusion402097). We evolve the NBI ions during the complete thermalization process and we calculate the amount of NBI ions loss in the edge region due to neutralizations. Results indicate the NBI losses for various injection geometries, various engineering parameters and various assumptions on the magnitude of the background neutral densities.

【 授权许可】

Unknown