According to Mr. Diaz, "[Ad Astra is] getting ready to fly the VASIMR engine on the International Space Station (ISS). It is a 200-kilowatt plasma rocket, the most powerful rocket ever built to fly in space
Commercial Plasma Rocket Reaches 200 KW, an Important Milestone
The rocket will be first tested in space in October 2013, aboard the International Space Station.
related thread from 2008:
If the VASIMR test on the ISS is successful.