Extension of the range for reproduction and transfer of the unit of magnetic induction
of the constant field into the strong-field region
News from Member - VNIIM, Russia
The D.I. Mendeleyev Institute for Metrology (VNIIM) has upgraded the State primary measurement standard of units of magnetic induction, magnetic flux, magnetic moment, and magnetic induction gradient GET-12 in terms of expanding its range for reproducing and transferring the unit of magnetic induction of a constant field from 1 mT to 1.5 mT.
This expanding responds to the growing use of modern NMR magnetometers and the improved accuracy of magnetic induction measuring instruments based on the Hall Effect.
VNIIM developed and implemented innovative solutions to reproduce magnetic induction in the range from 1 mT to 25 mT, achieving uncertainty of 2 ∙ 10-6 for transferring the unit of T. In particular, a MZ-type quantum cesium magnetometer was developed, based on double radio-optical atomic magnetic resonance. It operates using the allowed electronic structure of cesium atoms within the 1 – 25 mT range.
The advantage of the developed magnetometer over traditional magnetometers is the possibility of using a significantly reduced volume of the sensor’s sensitive element (Ø 10 mm sphere) while maintaining a high signal-to-noise ratio in the frequency range of (3.5 – 90 MHz), which is optimal for building the electronic part of the equipment.
To reproduce magnetic induction in the range from 25 mT to 1.5 T, an approach was applied based on using a highly homogeneous electromagnet, a stabilized current source, and a reference NMR magnetometer, specially developed in collaboration with BINP.
The relative uncertainty of magnetic induction reproduction in the range of 1 mT – 1.5 T ranged from 1 ∙ 10-6 to 5 ∙ 10-6, respectively.
These developments make it possible to create a unified system for metrological assurance of magnetic induction measurements in the expanded range of 10-8 – 1.5 T at the primary standard level.
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Denis Belyakov, Head of the Laboratory of Magnetic Measurements
d.i.belyakov@vniim.ru