Olin Corporation

William W Smith

Steve Knowles

Mark A Simon

Richard Dale Smith

Steven C Knowles

R J Cassady

An arcjet thruster has a body defining a constrictor and nozzle constituting an anode and forming an arc chamber. An elongated rod constitutes a cathode spaced from the constrictor by a gap generally coextensive with the arc chamber. An electrical potential is applied to the anode and cathode to generate an electrical arc in the arc chamber from the cathode to the anode. Propellant is supplied to the arc chamber with generation of the arc so as to produce thermal heating and expansion of the propellant through the nozzle. The thruster employs several features which improve its performance. One feature relates to the use of propellant blends with high specific impulse additives. Another feature relates to injection of the high specific impulse additive into the bulk propellant feed at the region of the cathode tip. Still another feature relates to recirculation of a small fraction of propellant from the constrictor region of the arc chamber and injection thereof into the bulk propellant feed at the region of the cathode tip. A final feature relates to regeneration and reaction of the bulk propellant feed within the structure of the anode body and circulation to the region of the cathode tip.

Performance arcjet thruster

An arcjet thruster has an anode body forming a constrictor and a nozzle which define an arc chamber. The thruster also has a cathode in the form of a rod having a tip and being spaced upstream from the constrictor. The thruster employs several features which reduce anode and cathode erosion and increase the operational life of the thruster. One set of features relate to the employment of cathode and anode shaping. Another feature relates to the use of a propellant injector having a series of radially and tangentially arranged passages for providing direct injection of propellant gas into the arc chamber and enhanced convective cooling of the anode.

Lifetime arcjet thruster

An arcjet thruster has a constrictor and nozzle defining an arc chamber. The constrictor has an insulator and an anode. The constrictor defines a subsonic-to-supersonic transition zone axially coextensive with the inculator and anode. The anode is disposed side-by-side with the insulator and located upstream therefrom. A rod defines a cathode spaced from the anode by a gap. An electrical potential is applied to the anode and cathode to generate an electrical arc in the chamber which produces thermal heating of propellant gases flowing through the chamber and expansion thereof through the nozzle. Location of the insulator downstream from the anode causes diffusion and attachment of the arc to occur at the region of the anode in the constrictor and prevents movement of the arc diffusion and attachment region downstream past the insulator to the nozzle in response to propellant gas mass flow variations through the constrictor. The thruster can also include an expansion and compression cavity in the arc chamber to provide a low pressure region at the anode for arc attachment and diffusion. Further, a zone of thermal and mechanical isolation can be provided between the anode and insulator to reduce the temperature at the insulator and displace its location farther away from the region of arc attachment and diffusion at the anode. Still further, a passage is defined through the insulator to provide a path for secondary flow of propellant gas into the chamber downstream of the arc attachment and diffusion region in order to reclaim frozen flow losses.

Arcjet thruster with improved arc attachment for enhancement of

A hybrid electrothermal/electromagentic arcjet thruster has a cylindrical body with a longitudinal central axis, a plurality of electro-thermal propulsion mechanisms defined in the body in radially and circumferentially spaced relation about and extending along the central axis, and an electromagnetic propulsion mechanism defined in the body coaxially along the central axis thereof, between the electrothermal propulsion mechanisms and extending downstream thereof. Each electrothermal propulsion mechanism has tandemly-arranged constriction and expansion zones and are operable to concurrently receive a flow of gaseous propellant through the constriction zone and generate an electric arc therethrough to the expansion zone. The arcs interact with the propellant flows such that the latter are partially ionized and electrothermally accelerated through the expansion zones. The electromagnetic propulsion mechanism has an expansion chamber which communicates with, and extends downstream of, the expansion zones. The electromagnetic propulsion mechanism is operable to concurrently receive the flows of electrothermally-accelerated partially-ionized propellant in the expansion chamber and generate a radial current flux and an azimuthal magnetic field which interact with one another and with the flow of propellant such that the latter is electromagnetically accelerated at a higher rate than the electrothermal acceleration thereof.

Hybrid electrothermal/electromagnetic arcjet thruster and

An improved efficiency arcjet thruster has a constrictor and electrically-conductive nozzle anode defining an arc chamber, and an electrically-conductive rod having a tip spaced upstream from the constrictor and defining a cathode spaced from the anode by a gap generally coextensive with the arc chamber. An electrical potential is applied to the anode and cathode to generate an electrical arc in the arc chamber from the cathode to anode. Catalytically decomposed hydrazine is supplied to the arc chamber with generation of the arc so as to produce thermal heating and expansion thereof through the nozzle. The constrictor can have a electrically insulative portion disposed between the cathode tip and the nozzle anode, and an electrically-conductive anode extension disposed along the insulative portion so as to define an auxiliary gap with the cathode tip substantially smaller than the gap defined between the cathode and nozzle anode for facilitating startup of arc generation. The constrictor can also include an electrically-conductive electrode with a variable electrical potential to vary the shape of the arc generated in the arc chamber. Also, the cathode is mounted for axial movement such that the gap between its tip and the nozzle anode can be varied to facilitate a generally nonerosive generation of the electrical arc at startup and reliable steady state operation. Further, the arc chamber can have a nonparallel subsonic-to-supersonic transition configuration, or alternatively solely a nonparallel supersonic configuration, for improved arc attachment.

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Seattle, WA, United States of America

William W Smith