2004 Fiscal Year Final Research Report Summary
Development of Multi-Channel Magnetic Field Sensor Utilizing Faraday Elements
| Project/Area Number |
13480131
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
TSUJI Shunji Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Associate Prof., 原子炉工学研究所, 助教授 (90272723)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMADA Ryuichi Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Professor, 原子炉工学研究所, 教授 (40206181)
TSUTSUI Hiroaki Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Assistant Prof., 原子炉工学研究所, 助手 (20227440)
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| Project Period (FY) |
2001 – 2004
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| Keywords | Faraday effect / magnetic field sensor / polarimeter / cross Nichole method / Zeeman effect laser / heterodyne / photoelastic modulatro / magnetic confinement |
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| Research Abstract |
To develop a polarimeter which measures magnetic field strength by the use of Faraday elements, the cross Nichole method, polarization modulation method and polarization rotation method were tested and compared.
Although the cross Nichole method does not have enough accuracy, which depends on the polarization angle, it was confirmed that its fast response and low cost is superior to the two heterodyne methods.
The measurement accuracy of the polarization modulation method utilizing two photoelastic modulators also depends on the polarization angle ; the standard deviation has a maximum of about 0.07 deg. around a polarization angle of 22.5 deg. and the signal to noise ratio was evaluated to has a peak of about 150 near 0 deg. The stability of the zero level is much better than that of the polarization rotation method. The variations of the zero level were within 0.01 deg.
For the light source of the polarization rotation, a Zeeman-effect laser was adopted to stabilize the zero level of the phase difference. The lasing, however, becomes unstable when a polarization maintaining optical fiber was used for free optical layout of multi-channel measurements. With an optical isolator, the temperature of which was well controlled to be constant, can reduce the backward light and hence the lasing was managed to be stable. When the whole optical isolator was put in a isotherm box, the measurement accuracy was demonstrated to be 0.01% for a long period of 10000 s.
The Verdet constants of candidate Faraday elements such as lead glass and ZnSe were evaluated under magnetic fields up to 5 T using a superconducting magnet.
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