Re: coil design for 1MHz Magnetic field

Sorry for not so complete description in my OP. I was not sure if I
should say too much to cause unnecessary confusions. But at this point,
I guess I shall definitely elaborate the problem in more detail, if you
can bear with me.

The specimen is in liquid form, that is, small magnetic particles
dispersed in some solvent, eg. water. So the volume of the specimen can
be as small as a few hundred microliters, but also very much flexible,
as long as it fits into the coil. In principle I would like to put my
specimen in the center of the coil, where the magnetic field strength
is stronger and more uniform. From E&M, the magnetic field is the same
everywhere inside an INFINITE long coil. But in reality, magnetic field
drops a lot even inside the coil but around the edge. So based on this
consideration, I would like to have a coil of certain size to
well-envelop my specimen. But also a relatively larger inductance to
gain a larger magnetic field. In my LC resonance circuit, I also put a
very small resistance (0.25ohm) in series with the coil to monitor the
current flowing through the coil so to roughly calculate the magnetic
field strength inside the coil. But when I actually do the experiment,
I would short the resistor.

I also have the same question as of how the power fed into the circuit
would be distributed. I mean If I pump 5W into the loaded circuit, and
I would hope more power to be dissipated by my specimen (I'm not quite
sure at this point, how much I would actually need.), then power
dissipated by the coil would be reduced, which means the current
flowing through would be reduced too, which means the magnetic field
strength would be reduced. Then the power absorbed by my specimen would
be reduced. Well, I really can't think this through.

.

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