In previous update I said, that if fast charging of field is impossible for now, I gonna try to find a way how to slow down discharge rate. I found one, so here it is.
Interaction between a coil and a capacitor is kinda interesting one: coil itself tries to sustain current by any means and current is an amount of charge moving through wire each second, however energy needed to move one electron differs depending on your setup! It can be small, it can be large, and while you have limited amount of electromagnetic energy - it makes a difference.
For example, if you have 40J in a magnetic field and each electron takes 0.5J to move through your coil, you can move only 80 electrons in total, with current in mind it dictates coil discharge duration. Let's say, that we need to increase that. One way to do it is to use bulky coil (with greater inductance), with same current flowing it would have more energy, not a great option though - it will increase cost and make coil more inert. Second, neat way, is to tweak amount of energy each electron takes to move - this is where capacitors come to play.
First of all, where this energy comes from? It comes from voltage. Electron would move himself from negative (overpopulated by electrons) to positive (desert) side without need in external force, as it seeks lower energy state, but opposite is unnatural and some effort is needed. When you charge a capacitor - you move electrons in unnatural direction, where voltage is Q/C. Bigger capacitance means, that you can move more electrons without significant rise of voltage and therefore - less energy used to move same charge. That's how you can discharge same electromagnetic energy with same current longer and that's what we see in LC circuits, where period of oscillations is somewhat proportional to C.
So... Can we simply increase capacitance? Of course we can, but there are much more elegant approach to that, which I found today! Let's nickname it... Battery-handled discharge.
How effective it is? From previous theoretical updates: field charging process becomes very-very ineffective as it goes, so I tested it with a reduced charging time: