Magnetic and velocity fluctuation measurements in the REPUTE-1 reversed-field pinch plasma

Abstract

Magnetic and velocity fluctuations are studied in the REPUTE-1 [Plasma Phys. Controlled Fusion 28, 805 (1986)] reversed-field pinch (RFP). The first measurement of velocity fluctuation in an RFP plasma has been done using a Doppler shift of the O v(O4+, 278.1 nm) line. The fluctuation level increases as the radius of the viewing chord increases. Magnetic fluctuation measurements by an insertable probe reveal that the radial cross correlation of toroidal field fluctuation changes its sign at the radius slightly inside the reversal surface. The level of magnetohydrodynamic dynamo term is estimated from magnetic fluctuations at the surface correlation changes and oxygen velocity fluctuations measured with the chord distance of 115 mm. The dynamo term and that due to resistivity are the same level. This fact is consistent with Ohm’s law on which magnetohydrodynamic dynamo models are based.