Patents by Inventor William A. Hargus, Jr.

William A. Hargus, Jr. has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6525480
    Abstract: The operating characteristics of a linear geometry Hall plasma source scaled to operate in the 50 to 100 Watt power range are described. Two thruster acceleration channels are implemented-one of alumina and one of boron nitride. Differences in operation with the two channel materials are attributable to differences in the secondary electron emission properties. In either case, however, operation is achieved despite the lack of a closed electron current drift in the Hall direction, suggesting that there is an anomalous axial electron mobility, due to either plasma fluctuations or collisions with the channel wall. Strong low frequency oscillations in the discharge current, associated with the depletion of propellant within the discharge, are seen to appear and vary with changes in the applied magnetic field strength. The frequency of this oscillatory mode is higher than that seen in larger (and higher power) discharges, due to the decreased residence time of the propellant within the channel.
    Type: Grant
    Filed: June 28, 2000
    Date of Patent: February 25, 2003
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: William A. Hargus, Jr., Nathan B. Meezan, Mark A. Cappelli