Loss of Charged Particles in a Stellarator During Ohmic Heating

The average charged particle confinement times τ0 in hydrogen and deuterium plasmas during Ohmic heating in the B-3 stellarator have been determined. The observed values of τ0 are approximately proportional to the square root of the magnetic confining field and were less than the values expected on the basis of classical collisional diffusion. The low values of τ0 persisted when the system was, in theory, made hydromagnetically stable by the addition of helical stabilizing winding. It is inferred that the observed low confinement times are not due to a known hydromagnetic instability.