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

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Abstract

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 (ITER), 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 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.

Original languageEnglish
Pages (from-to)445-448
Number of pages4
JournalReview of Scientific Instruments
Volume70
Issue number1 II
DOIs
Publication statusPublished - Jan 1999

All Science Journal Classification (ASJC) codes

  • Instrumentation

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    Fujita, J., Matsuura, K., Kawahata, K., Fujiwaka, S., Itoh, S., Sato, K. N., Nakamura, K., Zushi, H., Sakamoto, M., Hanada, K., Jotaki, E., & Makino, K. (1999). A rotating coil probe for the magnetic field measurement on a long pulsed tokamak. Review of Scientific Instruments, 70(1 II), 445-448. https://doi.org/10.1063/1.1149281