Plasma position measurements in a tokamak with an iron core transformer

Two simple methods of estimating the plasma position in a large-aspect-rati o, low-beta(p) tokamak with an iron core transformer are demonstrated: a ma gnetic diagnostic method and an optical method. The magnetic diagnostic met hod utilizes an array of magnetic pickup coils to measure the poloidal magn etic field produced by the plasma current. To include the effects of toroid icity and an iron core transformer, the correction factor was calculated wi th the magnetic material (or iron core) inside the calculation domain and i ncorporated in the analysis. The evolution of horizontal and vertical displ acement of the plasma center obtained in this way is used to control the KA IST-Tokamak plasmas. To compare the plasma position estimated using the mag netic pickup coils, a simple optical method is also demonstrated on KAIST-T OKAMAK using a composite video signal from a charge-coupled device (CCD) ca mera. The two results are in good agreement.