If Tokamak toroidal discharges are operated with $q<\mathrm{}3\mathrm{}$, relaxation oscillations are observed to occur involving alternate contraction and expansion of the plasma. It is shown that the detailed properties determined for these oscillations on the Canberra experiment can be explained on the basis of the newly discovered trapped-particle pinch effect.

• Received 13 July 1970

DOI:https://doi.org/10.1103/PhysRevLett.25.916