Ebrahimi progress

A subset of the VASIMR process is the Ebrahimi, alfvén recombination. This is being evaluated in the lab. I'd not say "tested" yet.

They can get 10-20 km/s upstream. This scales with the strength of the magnetic field, for which they got good tests up to 9 kV. Thrust in turn correlates with plasma density which their equipment kept low, 1-3e-6 kg/m³; and with the velocity-squared of the exhaust; and with the area of the plasma column cross section. It has so far transpired that their speedy upstream velocities suffer interference, and that they want a bigger lab but they would say that.

Keep in mind the very physics are still young and may involve Navier-Stokes.