Showing papers on "Arcjet rocket published in 2006"

Interaction of Charged Spacecraft with Electric Propulsion Plume: On Orbit Data and Ground Test Results

Abstract: On-orbit observations and ground tests demonstrate interaction between charged spacecraft and electrothermal thruster-generated plasma. On-orbit measurements and test results are presented for plasma diagnostics and solar array performance during long-term exposure of flight solar panel. The long-term performance of a flight 70 V 2mtimes4 m GEO solar array exposed to a 2 kW arcjet plasma environment was studied

Experimental Simulation of Magnetic Sails

Abstract: In order to simulate the interaction between the artificially deployed magnetic field produced around a magnetic sail spacecraft and the solar wind, a laboratory simulator in a space chamber was designed. As a solar wind simulator, a high-power magnetoplasmadynamic arcjet was operated in a quasisteady mode of about 0.8 ms duration to provide a high-speed hydrogen plasma plume of about 0.7 m in diameter, which is accelerated to above 20 km/s with high plasma densities around 10 17 -10 19 m -3 . Into this high- density and high-velocity plasma jet, a small coil of 2-cm-diameter was immersed to obtain 1.9-T magnetic field at the center of the coil. These devices are operation in a large 2-m- diameter space chamber, and the formation of a magnetic cavity was observed around the coil. From the analysis of scaling parameters, it is found that the laboratory experiment of the plasma flow around the coil of the magnetic sail corresponds to a sub-Newton-class magnetic sail.

Computational Simulation of High Enthalpy Arc Heater Flows

Abstract: The flowfields in segmented constrictor-type arc heaters are simulated using a new Navier-Stokes code named ARCFLO3. The validity of the radiation and turbulence modeling employed in ARCFLO3 is assessed by comparing the calculated results with the existing experimental data obtained in the 20 and 60 MW arcjet facilities at NASA Ames Research Center. Comparison is made between the calculated and the measured data for arc voltage, heater efficiency, mass-averaged enthalpy, chamber pressure, heat flux at wall, and total enthalpy in the centerline region of an arcjet flow

Development of an Experimental Simulator of Magnetic Sail

Abstract: In order to simulate the interaction between the solar wind and the artificially deployed magnetic field produced around a magnetic sail spacecraft, a laboratory simulator was designed and constructed inside the space chamber (2m in diameter) at ISAS. As a solar wind simulator, a high-power magnetoplasmadynamic arcjet is operated in a quasisteady mode of ∼0.8ms duration. It can generate a simulated solar wind flow that is a high-speed (above 20km/s), high-density (above 1017m-3) hydrogen plasma plume of ∼70cm in diameter. A small coil (18mm in diameter), which is to simulate a magnetic sail spacecraft and can obtain 1.9-T magnetic field strength at its center, was immersed inside the simulated solar wind. Using these devices, the formation of a magnetic cavity (∼8cm in radius) was observed around the coil, which indicates successful simulation of the plasma flow around the coil (simulated magnetic sail spacecraft) in the laboratory.

Laser absorption velocimetry of plasma flow in two-dimensional magnetoplasmadynamic arcjet

Abstract: Experimental velocimetry in the discharge chamber of a two-dimensional magnetoplasmadynamic (MPD) arcjet, fabricated for experimental internal flow measurement, was conducted to investigate the acceleration process for hydrogen propellant. In the experiment, we evaluated the neutral atom velocity and the temperature from the laser absorption spectroscopy using a tunable diode laser. The results using two types of anode, a flared-type anode and a converging-diverging (C-D)-type anode, were compared for the case with a discharge current of 13 kA and a mass-flow rate of 0.65 g/s. It was found that a large velocity slip between the ions and the neutrals prevented the acceleration of the neutral particles. This velocity slip is expected to reduce thrust performance because the flow with ion-neutral slip requires additional electric power compared to the flow without velocity slip. The velocity slip was reduced in the case of the C-D anode compared to the flared anode because of strong ion-neutral momentum coupling in the throat region of the C-D anode.

Modelling of a CO2-N2 Plasma Flow in a Supersonic Arcjet Facility

Abstract: The Martian-type CO 2 -N 2 plasma flow obtained in the plasma generator of the SR5 arcjet facility has been simulated using two complementary fluid descriptions. An inviscid multitemperature monofluid description has firstly been used to evaluate the importance of the different chemical and exchange processes between the flow species. Then, a one-temperature Navier-Stokes description has been used to evaluate the influence of viscous and rarefaction effects. In the nozzle throat region, heat addition from the arc firstly leads to the establishment of a translation-vibration disequilibrium. Near the end of the nozzle throat, temperature and pressure increases allow more efficient exchange processes and lower this disequilibrium. In the nozzle diverging region, chemical and vibrational processes are quickly frozen as the flow strongly expands. Furthermore, a translation-rotation disequilibrium also occurs near the nozzle exit. Navier-Stokes simulation results evidence a quick increase of the diverging section boundary layers, and therefore most of the diverging section is in a fully viscous interaction regime. Moreover, rarefaction effects are predicted to appear near the nozzle exit walls. The experimental measurements carried near the nozzle exit confirm the thermal disequilibrium regime of the flow, predicted by the simulation results.

Ground experiment on arcjet thrusters(II) Electric characteristic analysis

Abstract: The discharge plasma physics characteristic and power unit output characteristic on arcjet thruster were analyzed.The positive slope control of output characteristic was achieved by means of the design of constant-current control and superposition positive feedback voltage.The arc operating was in the high-voltage mode state and the thruster worked steadily.The effects of electric parameters on working performances is obtained by experiment test.

Performance and Plasma Characteristics of Pulsed Magneto-Plasma-Dynamic Arcjet Thrusters with Cusp and Divergent-Nozzle Applied-Magnetic-Fields

Abstract: A two-stage magnetic field with cusp and divergent shapes was applied in a magneto-plasma-dynamic (MPD) thruster discharge chamber. The thrust efficiency intensively increased with enhanced thrust and unchanged discharge voltage because of more effective ionization/heating and swirl acceleration due to the applied magnetic field. When the magnetic field became much stronger and the arc current became much higher, the thrust approached the self-magnetic thrust. As a result, an optimum magnetic field strength existed. The plasma flow was observed by a high-speed camera, and plasma density, temperature and velocity were measured with electrostatic probes. Through the magnetic nozzle the exhausted plasma rotated and spreaded radially-outward, and the plasma density decreased near the central axis. Accordingly, the plasma characteristics agreed with the measured thrust performance, considering intensive plasma heating due to Hall current and swirl acceleration, i.e. conversion from azimuthal kinetic energy to axial kinetic energy.