A dynamo is necessary for reversed field pinch (RFP) configuration sustainment in a continuous way or oscillation cycles by self-organization. A dynamo velocity field from electrostatic drift is studied in three-dimensional (3D) equilibrium for Keda Torus eXperiment RFP plasmas in quasi-multi-helical (QMH) and quasi-single-helical (QSH) states. The 3D equilibrium reconstruction is computed by VMEC code. It is found that the electrostatic potential provides helical modulation of plasma flow in QSH states. The electrostatic potential in QMH states is processed as a superposition of limited helical harmonics, and it shows an axisymmetric pattern. Non-axisymmetric components are negligible in QMH states because of flux surface averaging of the electrostatic field and corresponding electrostatic drift flow. The electrostatic drift velocity is comparable to the total plasma drift in QSH states; this implies that the electrostatic drift may play an important role in sustaining the helical configuration in RFP plasma.
Effects of magnetic helicity on 3D equilibria and self-organized states in KTX reversed field pinch