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Author: Wendell Horton
Requested Type: Pre-Selected Invited
Submitted: 2016-02-15 11:49:03

Co-authors: A. V. Arefiev, C. Michoski, Y. Peysson, M. Goniche

Contact Info:
Institute for Fusion Studies,UnivTexasAustin
RLM 11.222 Speedway
Austin, Texas   78712-1

Abstract Text:
The propagation, scattering and absorption of the lower hybrid and electron cyclotron RF waves used to control fusion plasmas is analyzed for models of WEST and EAST. Drift wave turbulence driven by steep ion and electron temperature gradients in H-mode and I-mode divertor tokamaks scatters the RF waves used for heating and toroidal current drive [Horton et al. Peysson et al.]. Both the 3-5GHz lower-hybrid (LH) and the 170GHZ electron cyclotron (EC) waves experience scattering and diffraction during propagation through the complex density of structures. While ray equations are traditionally used in to calculate the spread of the rays [Goniche et al.], here we introduce a 3D spectral code with 4-coupled partial differential equations for the 3-componets of the RF electric field and the parallel electon current. The local linear system yields the Stix matrix coupled to the fluctuating parallel electron current density. In the local collisionless limit the vanishing 4X4 determinant yields the coupled ES and EM RF-waves. Their polarization [local eigenvectors] vary with the local plasma parameters. High order time integrators solve for E-vector and j||. The evolution, while limited in time compared with ray codes, shows the complex coupling of the fast and slow RF modes in the turbulent plasma. The approach is motivated by the observed X-ray spectra that are broader than those from ray- quasilinear models and the ease of including background density fluctuations effects on the RF electric fields in spectral code simulations.
The work is supported by the US Department of Energy under Contract DEFG02-04ER-54742 and IFRM-Cadarache and INSTN. The simulations were performed at TACC Univ Texas,

if poster place with C_MOD RF group posters on similar subject of RF control
Plasma Production and Heating or in the Plasma Properites