0
$\begingroup$

I'm trying to work out a weird case of the magnetic force exerted on a current-carrying loop, and could use some help understanding things.

suppose you have an air core inductor / coil, which, when a current is passed through it, generates an axial magnetic field within the coil. would that field then interact with the wires of the coil itself? if so, from the right hand rule, I would expect that the direction of the force on the wires around the coil would either force the coil to expand/contract in diameter, depending on the direction of current flow and the internal b field. is this understanding generally correct? I'm not exactly sure how all the fields from each turn of the coil would combine at the edges of the coil where the wires are, though i'm pretty sure its not (ideally) perfectly axial along the length of the coil...

if that were the case, then i would suppose you could theoretically pass enough current through the coil that you could cause it to expand or contract - i'm wondering about how much current is required before the force becomes non-negligible, as i'm working on a pulsed RF generator where there could be hundreds to maybe 1000A flowing through inductors in a high-power resonant circuit (pulse powers of >100kW), and I want to be sure that the air-core inductors i'm designing are not going to experience significant mechanical stress that would cause the relatively thin (16-20AWG) magnet wire to deform and alter the inductance of the coils, which must be finely tuned and quite stable.

Improve this question
$\endgroup$
2
  • 1
    $\begingroup$ Read about "electromagnetic forming," in which a conductive object (e.g., a coin) is re-shaped by an extreme magnetic pulse created by an air-core coil. I don't know if the technique has any industrial use, but in demonstration/hobbyist versions, it is expected that a new coil will have to be used for each "shot," because the same magnetic force that crushes the coin literally explodes the coil. capturedlightning.com/frames/shrinker.html $\endgroup$
    – Solomon Slow
    Commented Oct 14, 2022 at 13:29
  • 1
    $\begingroup$ cool, thanks for the link! in the absence of the workpiece however, there would be no reciprocal force on the coil, and so I would not expect the same effect. after reviewing the problem a bit more, I believe there is no net force on the coil, as there would be an even force distributed around each section of each turn of the coil, which all cancel to 0 net force. i expect the interaction between turns of the coil is negligible, as are any radial components of the field. $\endgroup$
    – KPM
    Commented Oct 14, 2022 at 16:21

0

Reset to default