Joaquim Pereira Neto

Wave dissipation by electron Landau damping in low aspect ratio tokamaks with elliptic magnetic surfaces

Longitudinal dielectric permittivity elements are derived for radio-frequency waves in an axisymmetric tokamak with elliptic magnetic surfaces, for arbitrary elongation and inverse aspect ratio. A collisionless plasma model is considered. Drift-kinetic equation is solved separately for untrapped (passing or circulating) and three groups of the trapped particles as a boundary-value problem. Bounce resonances are taken into account. A coordinate system with the “straight” magnetic field lines is used. Permittivity elements, evaluated in the paper, are suitable to estimate the wave dissipation by electron Landau damping (e.g., during the plasma heating and current drive generation) in the frequency range of Alfven, fast magnetosonic, and lower hybrid waves, for both the large and low aspect ratio tokamaks. The dissipated wave power is expressed by the summation of terms including the imaginary parts of both the diagonal and nondiagonal elements of the longitudinal permittivity.Longitudinal dielectric permittivity elements are derived for radio-frequency waves in an axisymmetric tokamak with elliptic magnetic surfaces, for arbitrary elongation and inverse aspect ratio. A collisionless plasma model is considered. Drift-kinetic equation is solved separately for untrapped (passing or circulating) and three groups of the trapped particles as a boundary-value problem. Bounce resonances are taken into account. A coordinate system with the “straight” magnetic field lines is used. Permittivity elements, evaluated in the paper, are suitable to estimate the wave dissipation by electron Landau damping (e.g., during the plasma heating and current drive generation) in the frequency range of Alfven, fast magnetosonic, and lower hybrid waves, for both the large and low aspect ratio tokamaks. The dissipated wave power is expressed by the summation of terms including the imaginary parts of both the diagonal and nondiagonal elements of the longitudinal permittivity.

Radiofrequency parallel permittivity of magnetized plasmas in low aspect ratio tokamaks

The solution of the Vlasov equation is presented for axially symmetric low aspect ratio tokamak plasmas having magnetic surfaces with a circular cross section. The analytical expression for the parallel component of the dielectric permittivity tensor of trapped and untrapped particles is obtained. This expression is used for theoretical analyses of the low aspect ratio effect on the bounce-resonance wave dissipation. The evaluated dielectric tensor components can be used for computer calculations of the radio frequency (RF) field structure and the RF dissipated power in the low aspect ratio tokamak plasmas.

Radio Frequency Dielectric Characteristics of a Collisionless Laboratory Dipole Plasma

Transverse and longitudinal dielectric permittivity elements have been derived for radio‐frequency waves in a laboratory dipole plasma model by solving the Vlasov equation for trapped and untrapped particles accounting for the cyclotron and bounce resonances.

Wave Dissipation by Electron Landau Damping in Axisymmetric D‐shaped Tokamaks

Longitudinal permittivity elements have been derived for radio‐frequency waves in a toroidal plasma with D‐shaped magnetic surfaces. These dielectric characteristics are suitable to estimate the wave dissipation by electron Landau damping (e.g., during the plasma heating and current drive generation) in the frequency range of Alfven, fast magnetosonic, and lower hybrid waves, for both the large and low aspect ratio tokamaks.

Collisionless dissipation of radio-frequency waves in axisymmetric tokamak plasmas

Contributions of trapped and untrapped particles to the transverse and longitudinal dielectric permittivity elements are present for radio-frequency waves in a tokamak with circular cross-sections of the magnetic surfaces and arbitrary aspect ratio. Imaginary parts of the longitudinal permittivity elements are important to estimate the wave power absorbed by electron Landau damping (e.g., during the plasma heating and current drive generation) in the frequency range of Alfven, fast magnetosonic, and lower hybrid waves. Whereas, imaginary parts of the transverse permittivity elements are necessary to estimate the cyclotron-resonant wave dissipation at the fundamental cy-clotron frequency of ions and/or electrons. The dissipated wave power is expressed by summation of terms including the separate contributions of trapped and untrapped particles to the imaginary parts of both the diagonal and non-diagonal elements of the dielectric permittivity. The concrete computations are carried out for a tokamak plasma with the main TCABR parameters.