A Modified Flux Loop for the Determination of Plasma Position in IR-T1 Tokamak

We presented a new simple diagnostic based on poloidal magnetic flux for the determination of the plasma position in the IR-T1 tokamak. This instrument consists of two semicircle wires which are installed toroidally on the inner and outer sides of the tokamak chamber and are connected with each other. In order to receive the poloidal flux on the last closed flux surface (LCFS), this instrument is installed on polar coordinates so that the projection of it on the midplane lies on the LCFS. In reality, this instrument receives the difference between the poloidal flux on the inner and outer sides of the LCFS, which we needed in calculating the plasma horizontal displacement. The main benefits of our proposed instrument are that it is a simple and solid loop and also that its output is directly related to the plasma horizontal displacement. Based on this technique, we determined the plasma position, and to compare the result obtained using this method, an array of four magnetic probes is also designed, constructed, and installed on the outer surface of the IR-T1 tokamak and the plasma position is obtained from it. The results are in good agreement with each other.