Hello,
Is it possible to create a high-frequency (100KHz) high-amplitude (1 Tesla) magnetic field with standard lab equipment?
Having read the theory about air-core solenoids it seems I will need a very high current and very high number of turns in order to produce a 1 T magnetic field but this seems advantageous when compared to ferromagnetic core solenoids which, as I understand, will heat up due to inductive heating.
Does any one have any experience with this? How long will it take for the ferromagnetic material to heat up? Could I possible run the field for 1 second without any detrimental effects?
Are there any other methods of creating high-frequency high-amplitude magnetic fields?
Thanks for any advice!
You are describing a radio transmitter (or induction welder).
What do you want it for?
This is for testing magnetic field sensing equipment
1T is not reasonable without a ferro- or ferri-magnetic core. Certainly not for
continuous duty.
You need a core with an air-gap, within which the field will be strongest and predictable
from the geometry and the permeability of the core material (although this is somewhat
variable with core batch and temperature)
For 1T you need something that is mainly iron I think, ferrite doesn't go that high without
saturating. And you need to keep eddy currents down, perhaps fine laminations or iron
dust.
Perhaps a high specification audio transformer core might be adapted to the purpose.
MarkT:
1T is not reasonable without a ferro- or ferri-magnetic core. Certainly not for
continuous duty.You need a core with an air-gap, within which the field will be strongest and predictable
from the geometry and the permeability of the core material (although this is somewhat
variable with core batch and temperature)For 1T you need something that is mainly iron I think, ferrite doesn't go that high without
saturating. And you need to keep eddy currents down, perhaps fine laminations or iron
dust.Perhaps a high specification audio transformer core might be adapted to the purpose.
But wouldn't the iron heat up due to hysteresis losses despite the fact that it is laminated?
hairbair:
But wouldn't the iron heat up due to hysteresis losses despite the fact that it is laminated?
Yes, of course, but if you make an air cored magnet you will need extremely high currents to get that field strength and the copper wires will heat up and melt. That's why MRI scanner magnets use super-conducting coils and liquid helium cooling.
Russell.
I've heard an MRI makes a hell of a racket every time they fire it. When you see it used on TV they always leave out the real sound so it looks silent. (and you don't see the patient wearing earmuffs or their head wrapped in cloth to muffle the sound. )
raschemmel:
I've heard an MRI makes a hell of a racket every time they fire it.
I can of course, vouch for that, and it is very repetitive.
They provide earmuffs.
The forces in a MRI scanner coil are huge, and the field is modulated by a smaller coil
to sweep it across the range of interest, although that's a tiny fraction of the main field
it causes the whole structure to vibrate noisily.
A 1T field stores about 400kJ per cubic metre if I've done my sums right, the energy
density is proportional to the square of the flux density.