Yes, the coil distorts and touch the z axis. The idea is to use the toroid as a capacitor that when it reaches a certain critical density it fires its energy.
I thought of something else in the meantime. It goes in the opposite direction.
Take this picture as an example.
http://upload.wikimedia.org/wikipedia/commons/f/f3/2006-02-04_Metal_spiral.jpg
Make it a toroid. It is a spring also, but the coil is flat. So, as one puts energy in there, it stores energy in potential mechanical form and potential eletromagnetic form. It will expand and at a point it will touch a pin, which will fire towards the anode.