Phenomenon of onset in magnetoplasmadynamic thrusters
The performance of magnetoplasmadynamic (MPD) thrusters has been severely limited by onset. This destructive onset phenomenon refers to the abrupt increase in voltage oscillations accompanied by severe electrode erosion which occurs at a critical value of the current for a given mass flow rate. This research is aimed at explaining and quantifying onset. The steady, one-dimensional, self-field flow in the MPD thruster is first analyzed for frozen flow, equilibrium flow, and nonequilibrium flow. This quasi one-dimensional theory explains the behavior of efficiency and predicts a new mechanisms for the onset phenomenon. This model predicts that smoothly accelerating supersonic flow can exist only below a critical current level because of increasing back-EMF. This limit is interpreted as onset and correlates with the experimentally observed J/sup 2//m onset parameter. In order to quantify electrode erosion rates, the electrode-adjacent boundary layer is analyzed using the results of the quasi one-dimensional theory. The free-stream boundary conditions for the steady boundary-layer flow analysis are obtained from the results of the quasi one-dimensional theory.
- Research Organization:
- Carnegie-Mellon Univ., Pittsburgh, PA (USA)
- OSTI ID:
- 5008616
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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