A rotating coil probe for the magnetic field measurement on a long pulsed tokamak

J. Fujita, K. Matsuura, K. Kawahata, S. Fujiwaka, S. Itoh, K. N. Sato, K. Nakamura, H. Zushi, M. Sakamoto, K. Hanada, E. Jotaki, K. Makino
1999 Review of Scientific Instruments  
In order to determine the magnitude and the position of the plasma current in a long pulsed tokamak such as the International Thermonuclear Experimental Reactor ͑ITER͒, it is urged to establish a reliable method which is free from the zero-level drift of the integrator as well as the radiation damage for the steady-state magnetic field measurement. For this purpose, we have developed a hybrid system, a combination of a conventional magnetic probe for the measurement of fast varying magnetic
more » ... arying magnetic field and a rotating coil magnetic probe for that of slowly varying field. The rotating coil is energized by an air turbine to avoid electromagnetic interference and the induce signal with a constant rotation frequency is picked up through a transformer to eliminate mechanical contacts. An automatic gain control circuit is also designed for the compensation of rotation speed fluctuation. The system is proved to achieve a flat frequency response with a proper choice of cross over frequency for high-and low-frequency systems. The rotating coil probe is tested for over 170 h without any trouble. The probe was applied to the poloidal magnetic field measurement on the TRIAM-1M long pulsed tokamak, and proved to work satisfactorily.
doi:10.1063/1.1149281 fatcat:vepy7kvsmver3n466s4anod2li