Effect of Magnetic Axis Shift on Neoclassical Transport in Helical Torus

Neoclassical transport for large helical device (LHD) configurations is studied by solving the bounce-averaged Fokker-Planck equation. Numerical code employed in the present paper (CHD1) is much faster and more efficient than existing transport codes. Effects of the magnetic axis shift on the mono-energetic transport coefficients are studied in detail for the LHD configurations, revealing that a strong inward shift of the magnetic axis can reduce remarkably the neoclassical ripple transport

Localized Stability Criterion and Double Adiabatic Theory

The stability criterion for the localized interchange mode is reexamined on the basis of the magnetohydrodynamics with double adiabatic laws. In plasma with double adiabaticity, the localized interchange mode is stabilized significantly due to coupling with the sound mode. This stabilization effect may explain the observed stability of LHD plasma beyond the predicted stability boundary

The Analysis of Magnetic lsland Using Generalized Magnetic Goordinates

Abstract The generalized magnetic coordinates system, which describes magnetic fields with and without nested magnetic surfaces, is constructed for a simple analytic helical field involving magnetic islands. In order to analyze magnetic islands, the residue of a tangent map at the fixed points and the Fourier components of the perturbation of the magnetic field are studied