LOSSES IN PLASMA ACCELERATION.
Final technical rept. 1 Jun 67-31 May 69,
PLASMADYNE SANTA ANA CALIF
Pagination or Media Count:
A study was made of the flow pattern in a vacuum chamber using a hydrogen jet at room temperature. The measurements show that an eddy is developed in the chamber with circulation carrying flow back to the region of the thruster at a rate seven or eight times as great as the thruster flow. The surveys indicate that the flow pattern near the thruster may be approximated by laminar free jet theory. This theory, in turn, indicates that the rate of flow entrainment by the jet near the thruster is inversely proportional to the jet Reynolds number when the entrainment rate is expressed in dimensionless form. Accordingly, the entrainment rate should increase rapidly with increased gas temperature, decreased chamber pressure, or decreased mass flow. Initial measurements verify that a marked increase in entrainment rate is obtained when hot gas is used. This result is of interest because it is suspected that the entrained flow can be acted on by external discharge and fields in the vicinity of the thruster resulting in a change in the thrust reading. Another activity, concerned with understanding the operation of a plasma jet engine, has produced some excellent motion pictures showing the jet plume and the interior of the arc chamber simultaneously. These pictures allow a correlation to be made between the appearance of the plume and the operating mode of the arc. Operating conditions with rapid electrode erosion rates are included. Author
- Electric and Ion Propulsion