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.
It will be so cool if they use the new generation of nuclear reactors with the Vasimr engine and resurrect the X33/Venture Star program. Its such a shame it was cancelled because of main faults with fuel tank and after hey cancelled it a new tank was made to their specifications, bad timing of what, but with today's finical problems it seems wise.
They're both ion engines, just two different designs and operating principles.
The Standard Gen/ Next-Gen ion engines are designed for lower longer burns achieving faster speeds at lower acceleration. uses electrodes and multiple moving parts and needs more maintenance. A potentially huge benefit is a standard ion engine produces an electrical charge as a byproduct that could be harnessed and feed into the power system.
The Vasimr Ion engine uses electromagnetic field instead of electrodes, has very few and smaller moving parts that require less maintenance. The Vasimr engine also provides a larger thrust over a short amount of time, however in doing so in produces a huge amount of heat that needs to be properly dissipated. The strong electromagnetic fields needed for the engines also produces hazardous dangers for electronic devices on board and requires a much greater amount of energy.
Then, theoretically, the ion engine is a perpefual motion machine..... O.o