Self-sustained divertor plasma oscillations in the JET tokamak

A bifurcative behavior of the divertor and edge plasma with self-sustained oscillations has been observed in the JET tokamak. Two plasma states are ob served with high and low divertor densities. The oscillations between these two states are observed only within a certain core plasma density range an d for input powers above a threshold. The change of divertor;state has siza ble effects on the main plasma leading to inverted density profiles and a c lamping of the edge temperature which adversely influences the access to th e H-mode regime.