Showing papers on "Arcjet rocket published in 1977"

Recombination lasing in a magnetoplasmadynamic arcjet

Abstract: The plasmadynamic recombination laser concept is verified experimentally in a high‐power quasisteady MPD arcjet operating at 4 kA and 12 g/sec of argon. Measurements of the spatial variation of electron temperature electron density, and population densities in the arc exhaust flow confirm that inverted populations of the 4p to 4s ArII transitions are established by collisional‐radiative recombination of the ArIII ion. Using an optical cavity aligned transversely to the flow, recombination lasing of four such transitions, 5145, 4880, 4764, and 4727 A, is observed spectrophotographically and photoelectrically over the entire 1‐msec discharge.

Effect of Applied Magnetic Fields on Physical Processes in an MPD Arcjet

Abstract: which produced an essentially axial slowly diverging magnetic field in the electrode region. Argon was used as the propellant and the background pressure was maintained at about 5 x 10 ~2 torr. In the present experiments, discharge current (/) was varied from 300 to 1500 A and propellant mass flow rate (w), from 15 to 75 mg/sec, at applied magnetic field (B), measured at cathode tip, up to about 4000 gauss. The electrode assembly was mounted on a parallelogrampendulum thrust stand, and the electrical power for the arc was brought onto the stand through mercury pots. Deflection of the stand was sensed by a linear differential transformer. The total reaction force (thrust), Tty was measured, mounting the magnetic coil on electrode assembly. The reaction force which acts on the electrode assembly, rea, was measured, attaching the magnetic coil to the coil holder connected rigidly with a vacuum tank. In this case, the interaction force between current passing through the electrode assembly and applied magnetic field was excluded, evaluating it by reversing the direction of magnetic field. To check this technique, the interaction force was also measured at some operating points, using an electrode assembly in which the cathode is shorted to the anode. Using Tt and Tea, the reaction force which acts on the magnetic coil, Tmc, can be obtained from Tmc =Tt- TeSL. The current distribution on the cathode was examined, using the divided cathode, divided into central and outer parts, and operating the arcjet in quasisteady mode (operation time 1-3 msec). The current distribution on the anode surface was evaluated by furnishing electrically-insulated small electrodes (Fig. 2) on it. These electrodes were endurable in steady operation of the arcjet, and they were also used for the detection of rotating spokes.

Determination of the Excited State Density Distribution within a Nonequilibrium, Freely Expanding Argon Arcjet Plume

Abstract: : The distribution of the population densities of the excited states of argon was determined at two axial positions in the non-equilibrium, freely expanding plume of an argon d-c arcjet Narrow-line absorption and concomitant radial inversion were used to obtain densities of the first four excited states of argon, which include the two metastable and two resonance states Abel inversion of the absolute radiance measurements of emission from several spectral lines provided the number density of highly excited states, the excitation or electron temperature, and the electron number density The distribution functions observed were decidedly nonequilibrium, with the first four excited states ranging from a factor of two to a factor of ten larger than that required for Saha equilibrium with free electron density

Recombination lasing in a magnetoplasmadynamic arcjet

Abstract: The plasmadynamic recombination laser concept is verified experimentally in a high power quasi-steady MPD arcjet operating at 4 kA and 12 g/sec of argon. Measurements of the spatial variation of electron temperature, electron density, and population densities in the arc exhaust flow confirm that inverted populations of the 4p to 4s Ar II transitions are established by collisional-radiative recombination of the Ar III ion. Using an optical cavity aligned transversely to the flow, recombination lasing of four such transitions, 5145, 4880, 4764 and 4727 A, is observed spectro-photographically and photoelectrically over the entire 1-msec discharge.