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Hall Effect Measurement System
Summarize 10 kinds of magnetic field measurement methods
1.instrument parameter
The resolution is generally at the level of 0.1nt, which is far more difficult to achieve with a Gaussian meter!
The measurement process of fluxgate magnetometer sometimes uses positive measurement once, and then the probe is measured once in reverse. Data processing: the two results are added together, and then divided by 2. The goal is to eliminate the magnetic field deviation.
0.5% of meter accuracy reading
The meter ranges from 0.1nT to tens of thousands of nT, covering the range of geomagnetic field. But you can't measure such a strong magnetic field as a permanent magnet!
Meter bandwidth DC 0Hz ~ 1KHz magnitude
Probe remanence 1NT level, this everyone enough to buy, must be clear with the manufacturer! The remanence of the probe provided by the manufacturer is often larger ~10nT, such as China Metrology Institute.
Purchase Note: Tell the company whether to measure DC or AC magnetic fields. I once used a fluxgate magnetometer purchased from China Metrics Institute, which has only a few Hz bandwidth. If I want to measure the magnetic field noise of power frequency, I need to purchase a specially high bandwidth fluxgate magnetometer.
In particular, we need to measure the power frequency magnetic field noise, we must choose a high bandwidth fluxgate magnetometer. I have seen an engineering team helping a university laboratory detect ambient power-frequency magnetic field noise using a three-dimensional "Stefan Mayer Instruments" fluxgate magnetometer with a noise of less than 1pT/root Hz
2.probe size
The size of the probe depends on whether it is a uniaxial or triaxial field measurement. The uniaxial probe is much smaller than the triaxial probe.
3D probe: generally 2cm ~ 3cm level, specific reference to Bartingdon (Bartington, which is the best brand in the world, but the price is relatively high)
Uniaxial probe: Usually 1cm or smaller, the one I used was 8mm.
3.principle of physics
To understand the principle of fluxgate magnetometer:
First of all, we need to clarify the question "what is hysteresis loop"?
Secondly, make clear the non-linearity of hysteresis loop (also known as magnetic saturation phenomenon, or fluxgate effect, or transformer effect);
Finally, the principle of fluxgate magnetometer is deduced by Faraday's law of electromagnetic induction.
hysteresis loop