Excitation of toroidal Alfvén eigenmodes with counter-current NBI in the TCV tokamak

Nuclear Fushion

article

M. Vallar¹  M. Dreval²  M. Garcia-Munoz⁴  S. Sharapov⁵  J. Poley¹  A. N. Karpushov¹  P. Lauber⁶  S. Mazzi¹  L. Porte¹ 

[1]Ecole Polytechnique Fédérale de Lausanne ,(EPFL), Swiss Plasma Center

[2]Institute of Plasma Physics, National Science Center, Kharkov Institute of Physics and Technology

[3]V.N. Karazin Kharkiv National University

[4]Department of Atomic, Molecular and Nuclear Physics, University of Seville

[5]CCFE, Culham Science Centre

[6]Max-Planck Institute for Plasma Physics

关键词: tokamak;    fast particles;    TCV;    TAE;   

DOI  :  10.1088/1741-4326/acb644

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

In Tokamak á Configuration Variable (TCV), unstable modes excited by resonant interaction between the shear Alfvèn waves in continuum gaps and energetic particles have been observed in scenarios with neutral beam injection (NBI). TCV is a middle-size device (R_0/a = 0.88/0.25 ) equipped with a {1},mathrm{MW} , {25},mathrm{keV}tangential neutral beam injector. In this paper the phenomenology of modes excited with on-axis NBI is presented. The Alfvènic nature of the modes has been confirmed investigating their sensitivity against plasma parameters such as NBI energy, toroidal magnetic field, and cross-checking with the predictions from linear kinetic stability code. The mode radial profile is estimated using electron cyclotron emission measurement and agrees well with modelling results. In addition, the fast particle distribution function has been modelled using TRANSP/NUBEAM code. Even with counter-current NBI (leading to higher losses), the drive from the resonant particles is sufficient for the mode excitation. An ad-hoc additional diffusion model allows to estimate the fast particle transport, modifying the fast particle gradient at the mode location and matching the neutron rates.

【 授权许可】

Unknown