Sensing a Change in Size of a Circular Tokamak Plasma Using a Single Magnetic Probe: a Theoretical Approach

Abstract

A tokamak is a toroidal device in which the donut shaped plasma is confined by means of external magnetic field. The externally measured magnetic field due to the plasma column carries several information about the plasma and these include total plasma current, the position of plasma column centroid, the shape of plasma etc. To diagnose these mentioned parameters, several magnetic diagnostics are used and this requires adequate data processing, which is not always very straight forward. In contrary, present theoretical study focus on a rather simple approach of estimating magnetic field at a given location with respect to circular plasma to figure out the change in size of the plasma column. Moreover, this study reveals that the required estimation is very much sensitive to the choice of location for measurement of magnetic field and completely depends on the geometry of the tokamak, and hence tokamak machine-specific. Finally, a subtle approach is explored to make these observations more generalized and hence the usefulness of this approach for any other tokamak-like machine is established.