Richard Nies

The geometry of flux surfaces with quasi-poloidal symmetry

Quasi-poloidal (QP) magnetic fields have desirable properties for confining plasma: no radial drift of guiding centres (with positive implications for neoclassical transport), zero Pfirsch–Schlüter current and a lower level of damping for poloidal flows. Despite their attractive...

Geodesic extended modes in low magnetic shear tokamaks and stellarators

Theories of ion-scale microinstabilities in tokamaks and stellarators typically assume that the passing electrons respond adiabatically due to their fast propagation speed. However, when the magnetic shear becomes sufficiently small, ion-scale modes can extend far along the magne...