Differences Between the Toroidal and Poloidal Flux Loops in the Measurement of Plasma Position in Tokamaks

Abstract

We presented two magnetic techniques for the measurement of plasma position in IR-T1 tokamak: a poloidal flux loops and toroidal flux loop (diamagnetic loop) methods. In the first method, two poloidal flux loops were designed and installed on outer surface of the IR-T1 tokamak chamber, and then displacement of the plasma column center (Shafranov shift) determined from them. To compare the result, the diamagnetic loop with its compensation coil were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the poloidal beta obtained from them. Moreover a few approximate values of the internal inductance for the different possible profiles of the plasma current density are also determined. Then the Shafranov parameter and therefore the Shafranov shift were obtained. Experimental results compared and discussed. Comparison of results shows that plasma current density should have a flat profile that is acceptable for the ohmically heated tokamaks as IR-T1.