Anomalous particle pinch in tokamaks

An anomalous particle pinch in tokamaks has been known to exist since the T-3 tokamak. However, it is now known to occur in almost all tokamaks. No satisfactory explanation has been reported for it so far. A theory is given here for an understanding of this pinch based on an idea given earlier by the author. The induction electric field polarizes the trapped particles, producing a polarization charge density in the plane. The polarization electric field so produced crossed with the toroidal magnetic field leads to an drift of all the plasma particles, which has been shown to have a -averaged radially inward component , where is the Ware pinch velocity , and is the inverse aspect ratio. For most tokamaks is found to be of the order of the observed inward drift .