Low frequency fields driven by the Ergodic Magnetic Limiter at rational surfaces in rotating tokamak plasmas

Abstract

The rotating low frequency (RLF) field penetration and dissipation and the effect of ponderomotive forces driven by Ergodic Magnetic Limiter (EML) on the poloidal/ toroidal flow in tokamak plasmas are discussed. EML coils are represented as a sheet current expanded in Fourier series with poloidal/toroidal wave numbers M/N depending on coil shape and feeding. The Alfvén wave mode conversion effect in the RLF range is found responsible for wave dissipation at the rational magnetic surfaces q r = −M/N = 3 typical for EML coil design. Analytical and numerical calculations show maximums of LF field dissipation at the local Alfvén wave resonance ω = |k || cA| near the rational magnetic surface qr = 3 in Tokamak Chauffage Alfvén Brésilien. The poloidal rotation velocity U , taken into account in the dielectric tensor, can strongly modify the LF field and dissipated power profiles. Even stationary EML fields can dissipate at the local Alfvén wave resonance (U M/r A = k c A ). Preliminary estimations show that the stationary EML fields can decelerate the plasma rotation.

"Teoria e modelamento computacional de aquecimento de plasma por ondas de alfvén no tokamak TCABR"

“…Para o presente trabalho foi necessário reconstruir totalmente o código, incluindo rotação de plasma, colisões elétron-íon e troca de cargas. O estudo dos efeitos de rotação de plasma em baixa freqüência foi baseado nos artigos do autor [44,45].…”