Current research on reversed field pinches

In the reversed field pinch (r.f.p.), confinement is provided by the poloidal magnetic field of the plasma current and a toroidal field which has the opposite sign (i.e. is reversed) outside the plasma with respect to its value on the axis. This provides high magnetic shear which favours stability at high /?, and this can give confinement with relatively low magnetic fields. The reversed field configuration can be generated spontaneously by the plasma by a relaxation process known as self-reversal. In this paper the basic theoretical and experimental properties of the r.f.p. are discussed briefly and an account given of the latest experiments on Eta Beta II at Padua, which confirmed early observations on Zeta that when the configuration is set up slowly by using the self-reversal process, reduced fluctuations, longer confinement times and ohmic heating to temperatures of about 100 eV are observed.