Current drive drift waves as a possible mechanism for dynamo effect and transport in reversed field pinches

The possibility that a current driven drift wave turbulence may be responsible for the outward ion flux observed in Reversed Field Pinches (RFPs) is investigated; the latter flux was recently proposed as the driving mechanism of the dynamo sustaining the poloidal current in the external region of an RFP discharge. It is shown that this possibility can be supported by the linear theory of current driven drift waves. Finally, on the assumption that the transport is dominated by these instabilities, a scaling law for the temperature in RFPs is derived, which shows an approximately linear dependence on the current and a weak dependence on the size of the machine, in agreement with the experimental results. (author)