Application of HIBP for measuring evolution of radial electric field and plasma potential in the TUMAN-3M tokamak

In the TUMAN-3M tokamak high-density scenarios with line-averaged density $n> 2\cdot 10^{19}$ m$^{-3}$, evolution of plasma potential towards positive values was detected using the heavy ion beam probe (HIBP) diagnostics in co-NBI (neutral beam injection in the direction of plasma current). The results show that efficiency of the plasma rotation generation by the neutral beam injection (NBI) depends on the plasma density. In addition, radial electric field was directly measured in ohmic discharges by using HIBP in the two-point probing scheme; the effect of density on the radial electric field was detected.