Stabilization of global movement on a field-reversed configuration due to fast neutral beam ions

Experimental evidence for the global stabilization effect of neutral beam injection on field-reversed configuration (FRC) plasma has been found for the first time. The translation of FRC plasma, i.e., transferring the formed plasma into another vessel along a gradient of guiding magnetic field, is an important technique for both the current FRC experiments and a future fusion reactor to separate formation and confinement regions. However, the translation’s dynamic process causes global wobble movement of the plasma column. The stabilization effect induced by obliquely injected neutral beams on this global movement has been observed by both interferometry and magnetic measurement. The behavior of injected beam ions has been calculated numerically and suggests that the injected beam ions confined under a strong mirror field could produce effective ring-current at both ends of the plasma column. The stabilization effect of this ring-current on the global movement has been discussed by using a rigid body model.