Ionization instability and self-contained plasma edge model
A self-contained equilibrium model of the plasma edge is proposed whereby: (i) ionisation of the neutrals released by the material structure is not only an electron/ion source, but also the driving mechanism for a drift-like mode; (ii) marginal stability of the mode is brought about by electron Landau damping; (iii) plasma is conducted to the target plates along open field lines which, owing to the mode's radial magnetic field component, penetrate the plasma edge to a depth of a few centimetres. The theory provides expressions for the electron temperature at the separatrix and for the particle confinement time. The latter is almost identical to the Kaye-Goldston energy confinement time; these expressions are compared with measured or estimated values. The theory also predicts bifurcation to an equilibrium with higher energy content when a certain heating power is exceeded. Because it overlaps a region in which the equilibrium profiles change substantially, occurrence of the drift eigenmode requires the presence of a self-consistent radial field. It is shown that the electric field profile required by the theory is consistent with some observations.
Bibliographic Reference: Article: Plasma Physics and Controlled Nuclear Fusion Research, Vol. 2 (1993) pp. 195-202
Record Number: 199311525 / Last updated on: 1994-11-28
Original language: en
Available languages: en