Just found something interesting here which could help out the vasimr engine. Thorium nuclear reactors. Apparently it is much safer because it recycles its on waste for more power by using a particle accelerator. So if they use this I wonder how fast the ship could go. I think they should use a nuclear reactor to test how fast they can get the engine to go and not just with the vasimr plasma engine but with the Deep space 1 ion thruster.