You can also just stay on the site and wing your way through the slides.
They are using eight copper rods to deliver current. The ends of the rods are cylindrical and I wonder what effect if any that different geometries have. I also wonder about the level of erosion. Can graphite and ultimately graphene make a difference in performance? Has anyone experimented with either seven or nine poles? The use of eight is an obvious bow to mathematical convenience. However, such symmetry may be a mistake. Nine poles give some mathematical convenience and seven gives you none. And while we are at it we may as well also know what happens when one pole fails.
Does the initial spacing of the filament matter and can this be affected by the geometry of the cathode bars?
At this point it would be nice to know if the center core means anything.
How is the energy in the electron bead handled?
It sure beats building a bigger and bigger torus in the hope that speed can overcome the lack of strong containment. This system delivers containment and energy for the money shot.
Once this is shown to work and be understood, and this is certainly a large step in that direction, I want to see what can be achieved by replacing copper with graphene. I am anticipating a progressive improvement in performance that cannot happen with copper.
What has made me keen about this particular protocol is that it starts small and can be obviously be improved while staying small or even getting smaller. This is a real spacecraft engine.