Stability of equilibrium in rotating magnetic field current drive for sustaining field-reversed configuration

The stability of the rotation of the ion and electron fluids is studied in regards to the balance of the forces exerted on the electrons by the resistive friction and the rotating magnetic field (RMF) applied for the sake of maintaining a field reversed configuration (FRC) in steady state. A simple analytical model with infinite-long plasma, rigidly rotating ions, and electrons and uniform plasma density is used. The linear stability analysis of the equilibrium rotation is carried out in the reduced zero-dimensional model, which includes the effects of ion rotation, radial plasma flow and separatrix radius change due to the flux conservation within the flux conserver. The analytical expression that gives the stability criterion is derived from the eigenvalues of the linearized equations. Based upon the stability criterion, an interpretation of the present experimental results and comments on future experiments are given for the penetration of the RMF into the FRC. (C) 2002 American Institute of Physics.