®) VX-200 engine, a 200 kW flight-technology prototype. Results from high power Helicon only and Helicon with ICH experiments are presented from the VX-200 using argon propellant. Total VX-200 system efficiencies are presented from recent results with greater than 100 kW of RF power, and extrapolation from an empirical fit shows greater than 60% efficiency at less than 200 kW RF power. A two-axis translation stage has been used to survey the spatial structure of plasma parameters, momentum flux and magnetic perturbations in the VX-200 exhaust plume. These recent measurements of axial plasma density and ambipolar potential profiles, magnetic field-line shaping, charge exchange, and force measurements were made within a new 150 cubic meter cryo-pumped vacuum chamber and are presented in the context of plasma detachment. Recent results at 200 kW DC power input have shown a thruster efficiency of 72% at a specific impulse of 5000 s and a thrust of 5.7 N.