Gradiometers and induction

[Oseania]

Hi,


Because gradiometers measure the change in magnetic field and as such they are sensitive to ferromagnetic objects. If I would create fast changing magnetic field with electromagnet shouldn't I be able to use gradiometers to detect the induced magnetic field even for para- and diamagnetic materials. Basically para- and diamagnetic materials (e.g. stainless steel) should have higher conductivity than even mineral rich rocks so I should be able to see them?

Practically the electromagnets probably had to be quite big so I'm not sure if it would be feasible to carry them and the powering unit around.

[Krzysztof]

Hi Oseania.
Sensitive differential magnetometer detects any metal is detectable at close range.
My watch with 10cm always affect the outcome.
My stainless steel tweezers, too (because of its length shows little residual magnetization by the field of the earth).
Write the electromagnets do you mean?
Little ferite closed magnetic circuit to increase voltage for the IC can be tolerated, especially when it is halfway between the sensors.
For me the inverter operates at 1.3 MHz with a current of 40mA and is OK.
When you think of a welder or large coils for a few amperes, it is better to forget right away.
Much depends on the method of measuring the magnetometer.
Frequency magnet can not affect operation of the sensors.
50-100kHz in the method of MI, 60-70MHz in method Overhausen; pulses during the measurement of the PPM method.
Avoid large open an electromagnetic field.
Best regards Chris.

[Oseania]

I'm thinking that I would have bias- electromagnets that would be on top of the mineral rich rocks. Below the rocks I would have sensitive differential magnetometers (I can do this in this application). There would be about 50 cm of rocks and I would like to see ferro and diamagnetic materials.

[Krzysztof]

Hi Oseania.
Maybe these electromagnets can close the screen, sheet or film with CO-NETIC.
There would be no changes in the field, and only a homogeneous element.
Are these electromagnets are needed?
Give a little detail, it is difficult to invent something without preliminary data.
Maybe a sketch.
Rocks with high iron content will give the effect of walking on the surface of a steel bunker, from which you will not see anything.
Best regards Chris.

The solid rock will not see any gold or crystals - the specificity of the magnetometer.

[Oseania]

I was thinking electromagnets because I have lightly ferrous rocks that conduct electricity somewhat. If I need to detect paramagnetic materials I think that the ferrous rocks will mask them if I use normal gradiometer circuit. However the para/diamagnetic parts conduct electricity much better than the ferrous rocks. If I put high changing magnetic field to these parts, the eddy currents in para/diamagnetic parts should create much higher B field than in the rocks. What do you think?. Attached is the sketch.

[Oseania]

Another try with the image:

[Krzysztof]

Hi Oseania.
You're determined!
With large changes in all fields will work on a magnetometer!
Is this what you want?
Ferromagnetic rocks also give an answer. Your psycho magnetometer.
Maybe it's better to think about the magnetic field of the magnet, not so strong that it does not get away.
This will be the initial magnetic polarity: you can choose the strength of the field by changing the distance to the best answer.
This suggestion is not entirely scientific, but you are looking for results.
Someone on this forum indignant, but after the hardships of the interpretation of the famous rock you can count on results. Unfortunately, this is a difficult and tedious.

Maybe even think about using a PI, or rather, IB. The forum you will find more specialists in these methods.

With your idea will be a precursor of publishing your work.

Do not forget that you've drawn a differential magnetometer.
Under these conditions, distance sensors, should be 60-100cm, only the MI method, the direction of the Earth's magnetic field, the W/E, horizontally (lowest noise), unless you're not moving because the rock is the rock.
Best regards Chris.