Improvement of the performance of a mu -metal magnetically shielded room by means of active compensation (biomagnetic applications)

Brake ter, H.J.M. and Wieringa, H.J. and Rogalla, H. (1991) Improvement of the performance of a mu -metal magnetically shielded room by means of active compensation (biomagnetic applications). Measurement Science and Technology, 2 (7). p. 596. ISSN 0957-0233

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Abstract:	An active compensation technique is presented for improving the performance of a mu -metal magnetically shielded room. Active compensation is established by measuring the magnetic field inside the room by a SQUID magnetometer. The output of this sensor is amplified and connected to a coil surrounding the room. The magnetic field generated in this way compensates the measured field inside the room. Active compensation was tested for magnetic fields in the vertical direction in a shielded room with one mu -metal shield. At low frequencies a shielding improvement of typically 40 dB was obtained. Measurements performed on a room with two mu -metal shields indicated that the attainable improvement is not limited by the amount of mu -metal applied in the room. The active compensation set-up is described in detail and experiments performed on the two magnetically shielded rooms are presented and discussed.
Item Type:	Article
Copyright:	© 1991 Institute of Physics
Faculty:	Science and Technology (TNW)
Research Group:	Energy, Materials and Systems (EMS) Low Temperatures - Biomagnetism (LT)
Link to this item:	http://purl.utwente.nl/publications/60690
Official URL:	http://dx.doi.org/10.1088/0957-0233/2/7/004
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