Journal ArticleDOI
An actuator-disk model for azimuthally nonuniform MPD arcs.
James A. Fay,Robert A. Cochran +1 more
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TLDR
In this article, a model based on the physical assumption that the current flows in a single column and upon the mathematical assumption that azimuthal averages of mass, momentum, and energy fluxes are time-in variant is proposed.Abstract:
Recent experiments have shown that, under some conditions of operation, the current pattern in an MPD arc is azimuthally nonuniform and rotates with a constant angular velocity, which increases with current and applied magnetic field but decreases with propellant mass flow rate. A model for such a flow is proposed which is based on the physical assumption that the current flows in a single column and upon the mathematical assumption that azimuthal averages of mass, momentum, and energy fluxes are time-in variant. The model is thus analogous to the actuator disk model, which describes the flow induced by a propeller. Additional hypotheses are made concerning flow properties and arc motion which are based on a limited experimental and theoretical understanding of magnetically balanced arc columns. A dimensionless correlation of all existing experimental measurements is derived and a criterion for the existence of current spokes is suggested.read more
Citations
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Journal ArticleDOI
Experiments on Current Rotations in an MPD Engine
TL;DR: In this article, the anode is segmented into four sectors by narrow axial insulat- ing gaps and Rogowski coils measure simultaneously the a.c. current to each of the segments, and most of the, anode current is found to extend over an azimuthal spread of about 90° which ro- tates at frequencies near 100 kHz.
Journal ArticleDOI
Occurrence and behavior of current spokes in MPD arcs
Robert A. Cochran,James A. Fay +1 more
TL;DR: Pulsed MPD arc experiment, determining voltage characteristics and rotating current spokes occurrence and behavior as mentioned in this paper, was performed in the early 1990s, and was used to determine voltage characteristics of MPD arcs.
Journal ArticleDOI
Separation of Uranium Isotope by Plasma Centrifuge
TL;DR: In this article, a method of separation of isotopes by electromagnetic means is presented, which utilizes electromagnetic acceleration by the interaction between an electric current in a slightly ionized gas and an external magnetic field.
Journal ArticleDOI
Onset of rotating disturbance in linear Hall- current accelerator
TL;DR: In this article, the authors studied the near cathode magnetic field effect on instability in linear Hall current accelerators, using geometry of magnetic field extending from anode to cathode region.
Journal ArticleDOI
Turbulence-model predictions for a flat plate boundary layer
TL;DR: In this paper, a photomultiplier was used to demonstrate the absence of periodic oscillations in the range of 0.04-0.24 tesla for any combination of operating conditions.
References
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Journal ArticleDOI
Experimental investigation of an electric arc in transverse aerodynamic and magnetic fields.
W. C. Roman,T. W. Myers +1 more
TL;DR: In this article, an experimental study was made of the aerodynamic behavior and heat transfer of an electric arc of 200 to 400 amp which was held stationary in an atmospheric pressure cross-flow airstream of velocities up to 60 fps by a transverse magnetic field up to 50 gauss.
Journal ArticleDOI
Performance characteristics of a magnetic annular arc.
TL;DR: Magnetic annular arc thrust and current-voltage characteristics, using various working fluids, were studied in this paper, where the authors used various working fluid types and working fluids.
Journal ArticleDOI
Low environmental pressure MPD arc tests.
TL;DR: In this paper, the performance of a magnetoplasmadynamic (MPD) arc thruster was evaluated in the 15ft-diam, 65ft-long vacuum tank at NASA Lewis Research Center.
Journal ArticleDOI
Experiments on Current Rotations in an MPD Engine
TL;DR: In this article, the anode is segmented into four sectors by narrow axial insulat- ing gaps and Rogowski coils measure simultaneously the a.c. current to each of the segments, and most of the, anode current is found to extend over an azimuthal spread of about 90° which ro- tates at frequencies near 100 kHz.
Journal ArticleDOI
Electric arc stabilization in crossed convective and magnetic fields.
J. F. Klein,Y. Y. Winograd +1 more
TL;DR: In this article, electric arc stabilization in crossed convective and magnetic fields, discussed column slanting relationship to widening near downstream electrode, and discussed the relationship between column slant and column widening.