| Popis: |
®) 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 200 kW of 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. A semi-empirical model of the thruster efficiency as a function of specific impulse was developed to fit the experimental data, and reveals an ICH RF power coupling efficiency of 89%. The thruster performance at 200 kW is 72 ± 9%, the ratio of effective jet power to input RF power, with an Isp = 4900 ± 300 seconds. The thrust increases steadily with power to 5.8 ± 0.4 N until the power is maximized and there is no indication of saturation. Comparisons of the plasma flux to magnetic flux in the plume show evidence that the plasma flow does not follow the magnetic field at distances downstream on the order of 2 m. The plume is more directed when the ions are significantly accelerated. The planned ISS flight test of the VASIMR ® VF-200 Aurora experiment is discussed. |
