We are working on induction heating and we are having trouble to measure the high frequency magnetic field strength (about 1 kA/m)? We have the coil design (nos. of turns and dia) and we know the current. From these quantities, we are using solenoid equation to theoretically estimate the magnetic field value.
But is there any instrument to measure the field directly at these high frequency. Normal gaussmeter is not working. Moreover, any metallic probe may get heated up extremely fast due to magnetic induction.
Any help is well appreciated. Advanced thank you.
You can possibly use a serch coil for measuring the time varying magnetic field.
Wikipedia page of search coil
https://en.wikipedia.org/wiki/Search_coil
Simply you need to make a coil and connect it to oscilloscope to measure the induced voltage.
You can possibly use a search coil.
Wikipedia page of the search coil:
https://en.wikipedia.org/wiki/Search_coil
Simply you can make a coil and put it to your target point where you want to measure the magnetic field strength.
You will measure the induced voltage by a oscilloscope connected to the two node of coil and integrate it. Then you can deduce the magnetic field strength.
You need proper design of coil (number of turns and size) to have high accuracy and required frequency bandwidth.
It is not possible to directly measure the magnetic field with a static coil. A rotating coil is impractical at these frequencies. However, the field does not seem to have any DC component, so it is sufficient to follow the variation of the field which can be observed as induced voltage in a static coil. The field corresponds then strictly speaking to the integral of the measured voltage (volt-seconds).
Thanks Dr. Bombach and Dr. Zen for your kind replies. Will surely look into the search coils.
In the meantime, could you mention any packaged instrument or readymade set-up for the same, if any. Advanced thanks.
Yes, a pick up coil is the way to go, attached to an oscilloscope. To calibrate it, you can run an alternating current of known amplitude through a larger coil with a known diameter and number of turns, and then measure the voltage response in your pick up coil (which you would place inside the larger coil with axes parallel). You can calculate the magnetic field produced by the large coil of known geometry and known alternating current. Choose a few different alternating current values for the large coil and measure the resulting voltage in the pickup coil each time. Then you can plot pick up coil voltage vs B field in large coil. Now you have a calibration curve for the pick up coil. Now you can measure an alternating B-field of unknown amplitude. Remember to orient the pick up coil to obtain the maximum voltage in the unknown field to get the full amplitude of the unknown field. In summary you need a pick up coil, an oscilloscope with a bandwidth of at least 126 kHz, a source of alternating current, a way to measure the alternating current, and a large coil to generate a test field. Good luck!
For measurement of high pulsed magnetic field (1 Tesla and above) one can use CMR sensor.
https://www.highmagnetic.com/magnetic-field-measurement-system
Hi @Dr. Barid Baran Lahiri
Sir i am feeling same problem. Can you please tell me which solenoid equation you are using to theoretically estimate the magnetic field value of AC magnetic field.
I my air core solenoid Operate at 50kHz AC magnetic field, 48v, 3Amp, 8 nos. of turns, 60mm hight.
Thanks please
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