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Null-Balanced Torque Magnetometer in 60 kG with the Optical Feedback Circuit
Nariaki YAMAMOTO Naoki KAGAWA Kentaro KITAMURA Daisuke TAKIGAWA Takekazu ISHIDA
IEICE TRANSACTIONS on Electronics
Publication Date: 2002/03/01
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Superconductive Electronics)
Category: Instruments and Coolers
torque, low temperature, superconducting magnet, optical sensor, PID control,
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We have designed a torque magnetometer using a 60-kG split-type superconducting magnet. A balance torque compensates the torque acting on a sample in the magnetic field. The feedback circuit for a sample direction consists of an optical position sensor, a moving coil, and a PID controller. We measured the coil current to know a sample torque. The whole torque machinery is directly rotated by a stepping motor of angular resolution 0.0036. An advantage of the torque apparatus is a wide dynamic range up to 1000 dyncm. The sample temperature can be controlled between 4 K and 300 K.