In the pedestal, large bootstrap and Pfirsch-Schluter currents, arising from the steep pressure gradient, drive kink instabilities and enhance the drive for the peeling-ballooning modes. The latter triggers periodic plasma eruptions at the edge of a tokamak that significantly influence the pedestal properties, limiting the pedestal pressure gradient and degrading core confinement. The...
The Debye sheath is shown to vanish completely in magnetised plasmas for a sufficiently small electron gyroradius and small angle between the magnetic field and the wall. This angle depends on the current onto the wall. When the Debye sheath vanishes, there is still a potential drop between the wall and the plasma across the magnetic presheath. The magnetic field angle corresponding to sheath...