Electro-optic Bdot probe measurement of magnetic fluctuations in plasma

We propose a combined use of a Pockels electro-optic sensor with a pickup loop coil (Bdot probe) for the measurement of magnetic fluctuations in plasmas. In this method, induced fluctuating voltage on the coil loop is converted into an optical signal by a compact electro-optic sensor in the vicinity...

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Bibliographic Details
Published in:Review of scientific instruments 2022-10, Vol.93 (10), p.103540-103540
Main Authors: Saitoh, H., Nishiura, M., Nakazawa, T., Morikawa, J., Yoshida, Z., Osawa, R.
Format: Article
Language:English
Subjects:
Circuits
Coils
Cyclotron frequency
Cyclotrons
Electric noise
Frequency ranges
Magnetic variations
Magnetospheres
Optical communication
Optical fibers
Optics
Transmission lines
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Summary:We propose a combined use of a Pockels electro-optic sensor with a pickup loop coil (Bdot probe) for the measurement of magnetic fluctuations in plasmas. In this method, induced fluctuating voltage on the coil loop is converted into an optical signal by a compact electro-optic sensor in the vicinity of the measurement point and is transferred across optical fiber that is unaffected by electric noise or capacitive load issues. Compared with conventional Bdot probes, the electro-optic Bdot probe (1) is electrically isolated and free from noise pickup caused by the metallic transmission line and (2) can be operated at a higher-frequency range because of the smaller capacitance of the operation circuit, both of which are suitable for many plasma experiments. Conversely, the sensitivity of the current electro-optic Bdot probe arrangement is still significantly lower than that of conventional Bdot probes. A preliminary measurement result with the electro-optic Bdot probe showed the detection of a magnetic fluctuation signal around the cyclotron frequency range in the RT-1 magnetospheric plasma experiment.
ISSN:0034-6748
1089-7623
DOI:10.1063/5.0089031