A global dynamo in a reversed‐field pinch plasma

It is found that a reversed‐field pinch (RFP) dynamo uniformly generates most of the toroidal flux in a RFP plasma with a high magnetic Reynolds (S) number. Hereafter, this is referred to as the global dynamo. The toroidal flux generated by the global dynamo is proportional to the plasma current. The effective inductance in a RFP plasma increases with S number and remains constant against the changing plasma current. This means that the pinch parameter Θ is held constant, that is, the global dynamo has a self‐organizing effect sustaining a particular RFP configuration. By comparing simulation results and analysis of magnetic fluctuations, it is confirmed that a global dynamo is generated by the nonlinear evolution of the single‐helicity of the m=1 mode alone.