Hy Mag,
Here is the circuit I have arrived at. It is only notional for discussion.
Instead of answering the question in your post, it addresses the requirement, 120V 30A 60Hz input to highest possible magnetic field.
CIRCUIT FUNCTION
(1) The circuit uses no mains transformers between the mains supply and the bridge rectifier. This means that the capacitor will receive the maximum current at the positive and negative voltage peaks of the input voltage sine wave.
(2) The maximum voltage across the capacitor will be 110V * 1.414 (root 2) = 155.54- 2V (bridge VF)= 153.54 V peak. Call it 153V.
(3) The pass element is a GTO thyristor because they are probably easier to drive and potentially offer the highest current rating/cost ratio compared to an IGBJT, which tend to be expensive. The switching element is immaterial in terms of the circuit basic function at this notional stage though.
(4) The remaining diodes return the energy stored in the inductor back to the capacitor when the the pulse terminates.
(5) Because the input voltage is now 153V rather than 500V, the winding on the inductor will need to be adjusted accordingly.
INDUCTOR
(1) The inductor characteristics have a radical and overwhelming influence on the performance of this, or any other circuit, including the original circuit.
(2) The inductor core: material, dimensions, shape, and eddy current insulation, needs to be optimized.
(3) Likewise, the inductor windings need to be optimized. My first thoughts are that about five parallel windings will be required to minimize skin effect.
(4) It is not clear from the OP's posts, if the magnetic field generated by the inductor is required to do any work. If not, in theory, the circuit will use no power. Of course, because inductors particularly are far from perfect, there will be losses, but these can be minimized by good design. Note that pure inductors and capacitors do not dissipate any power because their voltages and currents are 90 degrees out of phase.