California Institute of Technology

Hughes Aircraft Company

Hughes Electronics Corporation

Leybold Aktiengesellschaft

Other

University of California

Space Systems/loral, LLC

Hughes Aircraft

Dan M Goebel

Jesse N Matossian

Richard Robert Hofer

Robert W Schumacher

Robert L Poeschel

Ryan W Conversano

Ronnie M Watkins

Robert W Conn

Gregor A Campbell

Edward A Adler

Ira Katz

Ioannis G Mikellides

Joseph Santoru

Klaus Hartig

Scott N Roberts

Anton Dietrich

Hans Aichert

Robert L Eisenhart

John W Gerstenberg

Robert Peter Dillon

Rainer Ludwig

Jennifer M Butler

Benjamin I Furst

Rolf Adam

Peter W Lord

David Younghee Oh

Julius Hyman, Jr

Christopher Bryan Stell

Jorge Delgado

Bao Hoang

David Eric Lewis

Karl Matl

Alfons Zoeller

Gonde Dittmer

Sean W Reilly

Lee Charles Rotlisberger

Giulia Becatti

Hans-Georg Betz

Denis Trofimov

Ronglin Liou

Peter Sommerkamp

William L Menninger

James T Crow

A Theodore Forrester

Hans Betz

Max Mayr

Friedrich Hass

Gregory Alan Carr

Alfred Thelen

Adele R Payman

A heaterless hollow cathode with high current discharge capability for use in electric propulsion devices is presented. The heaterless hollow cathode includes a thermionic emitter insert having a tubular shape and arranged inside a hollow cathode tube. The heaterless hollow cathode further includes a propellant feed tube that longitudinally extends from an upstream region of the hollow cathode tube into an inner volume of the insert. According to one aspect, an extension of the propellant feed tube into the inner volume of the insert is in a range from one quarter to three quarters of a total longitudinal length of the insert. The propellant feed tube is made of a refractory metal that is capable of withstanding temperatures above 2200 degrees Celsius with negligible evaporation. According to another aspect, the refractory metal is tantalum or tungsten.

High current heaterless hollow cathode

Systems and methods for embedding a thermal management system in an electric propulsion (EP) system is presented. According to one aspect, one or more oscillating heat pipes (OHPs) are provided within functional elements of the EP system. Each OHP includes channel segments that include a sealed working fluid. The channel segments are joined to form a continuous serpentine channel with a channel path that alternates between hot and cold regions of the EP system. According to another aspect, the functional elements of the EP system are reduced to a single monolithic structure with an embedded OHP. The single monolithic structure may be a single material or a multi material. According to yet another aspect, the functional elements are elements of a magnetic circuit of the EP system, including one or more of a backplate, an outer pole, an inner pole, or a center pole.

Thermally managed electric propulsion systems

Systems and methods for providing a heaterless hollow cathode for use in electric propulsion devices is presented. According to one aspect the cathode includes a thermionic emitter having a constricted upstream inlet compared to a downstream outlet of the emitter. The emitter is arranged downstream a hollow cathode tube. Constriction of the upstream inlet is provided by an inner cylindrical hollow space at an upstream region of the emitter having a diameter that is smaller compared to a diameter of an inner cylindrical hollow space at a downstream region of the emitter. A hollow transition region having a varying diameter connects the upstream region to the downstream region. According to another aspect, a ratio of the diameters of the two cylindrical hollow spaces reduces penetration of electric field, and therefore of electric discharge, into the upstream region of the emitter during operation.

Heaterless hollow cathode

A spacecraft includes a power train that includes a solar array, an electric propulsion subsystem, and a power conversion module. The power conversion module receives power from the solar array at a voltage, V; and delivers power to the electric propulsion subsystem at a voltage, V. The spacecraft is configured to operate at a varying distance, D, from the sun within the range of Dto D, Dbeing at least 1.3&#xd7;D. The solar array is configured to deliver power to the power conversion module at a voltage approximately equal to Vwhen the spacecraft is proximate to D.

Power train for deep space solar electric propulsion

A low-power Hall thruster gains significantly improved efficiency by a combination of features, including a single piece, h-shaped magnetic screen which enables a more efficient internal volume utilization as well as optimal magnetic shielding; an internally mounted cathode with varying diameter further decreases the footprint of the thruster; an anode with multiple baffles connected by axially oriented holes generates a highly azimuthally uniform propellant flow.

Low-power hall thruster with an internally mounted low-current hollow cathode

Hall thrusters with conductive coatings are disclosed. A Hall thruster comprises magnetic shielding in order to avoid collisions with the inner walls of its discharge chamber. By removing the source of erosion, the walls of the chamber can be removed reducing mass, cost and complexity of the thruster. A conductive coating, such as an aluminum coating, is deposited on inner screens between the discharge chamber and the magnetic poles of the thruster. The magnetic field within the chamber shields the conductive coating deposited on the inner and outer screens of the chamber.

Hall thruster with magnetic discharge chamber and conductive coating

A Hall thruster apparatus having walls constructed from a conductive material, such as graphite, and having magnetic shielding of the walls from the ionized plasma has been demonstrated to operate with nearly the same efficiency as a conventional nonmagnetically shielded design using insulators as wall components. The new design is believed to provide the potential of higher power and uniform operation over the operating life of a thruster device.

Metallic wall hall thrusters

A Hall thruster apparatus having walls constructed from a conductive material, such as graphite, and having magnetic shielding of the walls from the ionized plasma has been demonstrated to operate with nearly the same efficiency as a conventional non-magnetically shielded design using insulators as wall components. The new design is believed to provide the potential of higher power and uniform operation over the operating life of a thruster device.

An apparatus and method for achieving an efficient central cathode in a Hall effect thruster is disclosed. A hollow insert disposed inside the end of a hollow conductive cathode comprises a rare-earth element and energized to emit electrons from an inner surface. The cathode employs an end opening having an area at least as large as the internal cross sectional area of the rare earth insert to enhance throughput from the cathode end. In addition, the cathode employs a high aspect ratio geometry based on the cathode length to width which mitigates heat transfer from the end. A gas flow through the cathode and insert may be impinged by the emitted electrons to yield a plasma. One or more optional auxiliary gas feeds may also be employed between the cathode and keeper wall and external to the keeper near the outlet.

Compact high current rare-earth emitter hollow cathode for hall effect thrusters

A protection circuit (,) for a Traveling Wave Tube having multiple tone operation. The protection circuit (,) is a dual sensor (,) arrangement. One sensor (,) is an operational amplifier circuit (,) having a short time constant and a high threshold current. The first sensor (,) provides protection against short time scale faults. The second sensor (,) is an operational amplifier circuit (,) having a time constant higher than the first sensor (,) and a lower current threshold than the first sensor (,) to provide protection against long time scale events. The two sensors (,and,) are logically &ldquo;OR&rdquo;ed with each other and eliminate spurious shutdowns and circuit damage.

Protection circuit for traveling wave tubes having multiple input tones

A collector for collecting an electron beam in a traveling wave tube is disclosed. The collector has an input end for receiving the electron beam from the traveling wave tube. The collector also has a plurality of stages biased at given voltages and arranged along a common collector axis and positioned at a different axial position with respect to the input end. A stage is biased more negatively with a voltage than a successive stage positioned axially farther from the input end to generate an electrostatic focusing lens for focusing the electron beam toward successive stages thereby increasing the collection efficiency of the collector.

High efficiency collector for traveling wave tubes with high perveance

A traveling wave tube apparatus and method is disclosed. The traveling wave tube includes a slow wave structure such as a helix member. The helix member has an input end for receiving a microwave input signal having a selected power level and an output end for supplying a microwave output signal having a given power level. A microwave source is connected to the input end of the helix member for applying the microwave input signal to the helix member. An electron gun assembly is adjacent the input end of the helix member and has a cathode for injecting electrons as an electron beam through the helix member. A collector assembly is adjacent the output end of the helix member and has at least four collector electrodes for collecting the electrons in the electron beam. The power level of the microwave input signal is selected such that the given power level of the microwave output signal is at least 3 dB lower than the power level of the microwave output signal at saturation. The geometry of the electrodes and bias voltages applied to the electrodes are selected to optimally handle an electron beam of a traveling wave tube operating at least 3 dB backed off from saturation so as to maximize the collection efficiency. The geometry of the electrodes and bias voltages applied to the electrodes are selected such that the collector assembly generates a high level of backstreaming current when the traveling wave tube operates at saturation.

Efficient, highly linear traveling wave tube using collector with high

A traveling wave tube and method of operation is disclosed. The traveling wave tube includes a slow wave structure such as a helix member provided with input and output ends and located within a tube member. An electron gun assembly is adjacent the input end for injecting electrons as an electron beam along an axial path through the helix member. A magnetic focusing device generates a magnetic field having a given strength to confine the beam to the axial path. The given strength of the magnetic field is sufficient to confine the beam only when the power level of the microwave input signal is selected such that the given power level of the microwave output signal is at least 6 dB lower than the power level of the microwave output signal at saturation. Boron Nitride (BN) supporting rods are engaged between the tube and helix members for supporting and transferring heat away from the helix member.

Optimally designed traveling wave tube for operation backed off from

A cold-cathode, crossed field switch has a magnet system which generates a magnetic field that is radially-oriented about a switch axis and a planar electrode system which generates an axially-oriented electric field. These structures facilitate a switch whose capacitance, inductance and fabrication costs are all reduced from that of conventional cold-cathode, crossed-field switches. Magnets of the magnet system are arranged in two concentric annular rings with their north and south poles aligned either axially or radially. The planar electrode system includes a cathode, a source grid, a control grid and an anode which are arranged in a substantially parallel relationship.

Planar crossed-field plasma switch and method

Growing community of inventors

Tarzana, CA, United States of America

Dan M Goebel