Efficiency of Current Drive via Rotating Magnetic Fields*

The “rotamak” is a proposed thermonuclear fusion device which employs rotating magnetic fields (RMF) to generate an azimuthal current to produce a field-reversed configuration (FRC). The efficiency of the currents that produce the field reversal by RMFs was debated some forty years ago (1,2). The debate revolved around whether the currents would incur dissipation by the conventional Spitzer resistivity of plasma, perpendicular to a magnetic field, or whether some other relation between current and dissipation would be more appropriate. In a preliminary investigation that considers the problem afresh, more extensive computations capture rather curious plasma behavior that suggests a picture for current drive not easily related to the leading mechanisms for driving current.

1 N. J. Fisch and T. Watanabe, “Field reversal by rotating waves,” Nucl. Fusion 22, 423 (1982).

2 W. N. Hugrass, “Comments on the  paper by  N. J. Fisch, T. Watanabe, ‘Field reversal by rotating waves’,” Nucl. Fusion 22, 1237 (1982).