high frequency electromagnet

[warpexplorer]

Is it possible to make very small, low power, but high frequency electromagnets and stack them up or inside each other
to make a high field strength, high frequency magnet? or does the presece of other magnetic fields cause the same problems you would expect with only one coil?

[Ivan Seeking]

Okay, since no one has answered I will give the obvious answer. Please note that at very high frequencies other considerations may come into play, but nothing that I have indicates that this is the case.

The mutual inductance between two loops of wire is a function of the geometry - the size, shape, and relative positions of the coils. The current source for each loop is unimportant. See the Neumann formula.

Since the ideal circumstance for your stack would seem to require that all coil currents are in phase and that your solenoid stack is uniform, the stack of small coils should act exactly like a continuous solenoid. So, considering the possibility of fringe losses I would think a single solenoid provides the best case for efficiency.