That's great, but I wonder how heavy the nuclear reactor would need to be that provides the 2 MW to power this thing. Is this something we could practically loft into orbit with present-day rockets? (Ignoring the not-entirely-unreasonable-in-this-particular-case environmental objections to flying nuclear reactors through our atmosphere on failure-prone chemical rockets...)
I suppose, on the upside, that once you had this thing in space it could stay there -- a nuclear reactor plus plasma rocket which could just shuffle back and forth between Earth orbit and Mars/Jupiter/wherever, refuelling at every Earth stop.