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