Alas, high Isp (efficiency) comes with low power and (usually) high power system mass.
"The test was conducted in a vacuum chamber at GRC. The HiPEP ion engine was operated at power levels up to 12 kilowatts and over an equivalent range of exhaust velocities from 60,000 to 80,000 meters per second. The thruster is being designed to provide seven-to-ten-year lifetimes at high fuel efficiencies of more than 6,000-seconds specific impulse; a measure of how much thrust is generated per pound of fuel. This is a contrast to Space Shuttle main engines, which have a specific impulse of 460 seconds."
60,000 to 80,000 m/s is 6118 seconds; 80,000 is 8157 sec.
They do not quote a thrust level but it must be small. My rule of thumb is 20 kW per pound of thrust; this would mean 20/12 = 1.67 lb of thrust or 7.4 Newtons. The wording is very misleading because it does not quote thrust...
--Boris