The nonlinear dynamics of an inhomogeneous plasma with hot electrons and cold ions, in the frequency range below the ion cyclotron and magnetosonic frequencies, is studied in the presence of magnetic shear. Both the finite electron mass and electron stress-tenser effects are accounted for, permiting arbitrary parallel phase velocities. A class of nonlinear travelling solutions is found, which are fully determined by the boundary conditions in the infinity, even on closed nonlinear characteristics. For the typical tokamak scaling beta < (L-n/L-3)(2), two different regimes are distinguished. In the shear Alfven regime, beta much less than m(e)/m(i), the solution has the form of a complex vortex chain, possessing both the magnetic and flow components, supported by a self-organized localized plasma flow and poloidal field. In the drift-wave regime, m(e)/m(i) much less than beta much less than 1, the solution is a nonlinear electromagnetic drift wave, whose amplitude is determined by its wavelength and the angle of propagation.
Coherent nonlinear electromagnetic drift-mode structures
PEGORARO, FRANCESCO
1998-01-01
Abstract
The nonlinear dynamics of an inhomogeneous plasma with hot electrons and cold ions, in the frequency range below the ion cyclotron and magnetosonic frequencies, is studied in the presence of magnetic shear. Both the finite electron mass and electron stress-tenser effects are accounted for, permiting arbitrary parallel phase velocities. A class of nonlinear travelling solutions is found, which are fully determined by the boundary conditions in the infinity, even on closed nonlinear characteristics. For the typical tokamak scaling beta < (L-n/L-3)(2), two different regimes are distinguished. In the shear Alfven regime, beta much less than m(e)/m(i), the solution has the form of a complex vortex chain, possessing both the magnetic and flow components, supported by a self-organized localized plasma flow and poloidal field. In the drift-wave regime, m(e)/m(i) much less than beta much less than 1, the solution is a nonlinear electromagnetic drift wave, whose amplitude is determined by its wavelength and the angle of propagation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
