Here is a diagram of a single impulse in a train already established. Like a snapshot.
Pay attention to the bottom of the tower diagram and you will see little dots in the structure. That is the control coil and intensifier circuit to boost the potential value of the impulses to allow them to be higher then the ionosphere value. And yes it is a very high potential of around 360kv or so. Each gradient of voltage in our atmosphere has a layer like appearance. Like an onion. So to reach the upper ionosphere you would have to present to the plasma up there 360kv+ to get it to move down to the ground. Once you get it down to a certain level it will act like a vortex flow going to a drain or ground sink in this case. Remember we can manage this flow entirely by the strength of the rings of less dense plasma going upwards and the coil at the bottom of the tower.
The flow will start to weaken if the Impulses are not kept up and the flow will stop due to lack of potential to keep the flow going to ground.
Once the flow of plasma is going that means you should be able to draw as much current as the ionosphere has available and be able to attract more to our planet as it streams by. In effect strengthening the ionosphere in the process if carefully managed. The energy comes from the new plasma condensing around the planets atmosphere. Nothing will be taken from that and only what is extra that streams by our planet every single second of the day and when the Sun does get a little out of hand and energetically fires a shot at us we could divert most of that energy into other things like energy storage and just letting it go to the ground in a shifter way.. like releasing water from a hydroelectric dam over time.
Just remember there are additional things that are gonna happen when you squeeze a plasma or magnetically pinch it.
https://en.wikipedia.org/wiki/Pinch_(plasma_physics) So it should be impulse, Pinch, relax and collect. Impulse, Pinch, relax and collect... etc...
The pinch is to create a higher excitation of the plasma going through the control coil and the intensified rush of plasma through that coil is entirely harvestable upto the limits of that coil. <-Super conductors or plasma conduits anyone? How about a superconductor capacitor anyone?