Patents by Inventor Kwo R. Chu

Kwo R. Chu 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: 6313710
    Abstract: The interaction structure with integral coupling and bunching section and method of use of the present invention produces backward wave oscillations in an RF structure which combines ballistic bunching and extended beam-wave interaction in a complex resonator assembly. The complex extended interaction structure includes a five-gap electromagnetically-coupled cavity structure with a coaxial section inserted between the first and second cavities. The first cavity serves as a buncher cavity while the four subsequent cavities serve as energy cavities. In the coaxial section, beam and wave propagate in separate channels. The field in the buncher cavity is coupled to the four subsequent energy extraction cavities through the wave channel between the inner and outer conductors of the coaxial section, while the electron beam drifts along a cylindrical channel cut through the inner conductor of the coaxial section.
    Type: Grant
    Filed: May 4, 2000
    Date of Patent: November 6, 2001
    Inventors: Liming Chen, Hezhong Guo, Han Y. Chen, Ming H. Tsao, Tze T. Yang, Yi C. Tsai, Kwo R. Chu
  • Patent number: 5814939
    Abstract: A mechanically tunable magnetron injection gun (MIG) provides an annular, relativistic beam of electrons for injection into an axially aligned magnetic field of a gyrotron-class device. The electron emitter encircles a center electrode. Turning a knob adjusts the center electrode's axial position relative to the rest of the cathode. The adjustable center electrode provides an effective means for local field adjustment. The center electrode is located in a particularly sensitive electric field region and adjusts the electric field so as to tune the electron beam from the inside out. Adjusting the center electrode position while the device is in operation is a means for providing mechanical tunability (with respect to beam quality and transverse-to-axial velocity ratio) for the MIG.
    Type: Grant
    Filed: February 12, 1996
    Date of Patent: September 29, 1998
    Inventors: Kwo R. Chu, Larry R. Barnett, Chaoen Wang, Yih S. Yeh, Tze T. Yang, Han Y. Chen, Shih H. Chen, Yi C. Tsai, Trine Y. Dawn
  • Patent number: 4567401
    Abstract: A wide-band distributed coupler for coupling rf energy from an input waveguide into a tapered interaction waveguide in a traveling-wave amplifier comprising a plurality of channel filters connecting between the input and interaction waveguides, with each filter coupled to the interaction waveguide at the appropriate cross-sectional position along its tapered length where the interaction waveguide cutoff frequency approximately matches the wave frequency propagated by the filter. Each filter comprises, in one embodiment, a main coaxial cavity tuned to a distinct center frequency, a first simple isolation cavity for coupling rf energy between the input waveguide and the main cavity, and at least one second simple isolation cavity for coupling energy between the main cavity and the tapered interaction waveguide. This coupler is compatible both in bandwidth and geometry with the tapered interaction waveguide.
    Type: Grant
    Filed: June 12, 1982
    Date of Patent: January 28, 1986
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Larry R. Barnett, Yue-Ying Lau, Kwo R. Chu, Victor L. Granatstein
  • Patent number: 4554484
    Abstract: A complex cavity gyrotron designed for stable operation at high order modes. The device comprises circuitry for generating an annular electron beam, a coupled cavity disposed coaxially with the electron beam and having a first and second adjacent coaxial sections with the dimensions of these coaxial sections adjusted so that different modes with the same azimuthal eigen number but different radial eigen numbers are simultaneously resonant at approximately the same frequency in the two sections, and circuitry for generating an axial magnetic field within the cavity. Few, if any, combinations of modes other than the combination chosen will simultaneously resonate in the cavity thereby effecting higher order mode suppression. The present design has a low susceptibility to beam velocity spread and is effective for any combination of modes with identical azimuthal eigen numbers.
    Type: Grant
    Filed: August 29, 1983
    Date of Patent: November 19, 1985
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Michael E. Read, Yuval Carmel, Kwo R. Chu, Achintya K. Ganguly
  • Patent number: 4533875
    Abstract: A high power amplifier for amplifying millimeter-wave radiation comprising: a length of metallic waveguide tapered from a small cross-sectional end to a larger cross-sectional end; a magnetron-type electron injection gun for injecting a spiral beam of relativistic electrons at the small end of the waveguide for propagation axially therein so that the wall radius of the tapered waveguide increases in the downstream direction of the electron beam; an input coupler for launching electromagnetic waves to be amplified into the waveguide at the large waveguide end thereof such that the individual frequencies in the input waves are reflected at various points along the constriction of the waveguide taper so that they copropagate with and are amplified by the electron beam; and a magnetic circuit for generating an axial magnetic field within the tapered waveguide with a unique profile approximately in accordance with the following equation to maintain synchronism: ##EQU1## where the z subscript is the waveguide axial
    Type: Grant
    Filed: June 16, 1982
    Date of Patent: August 6, 1985
    Inventors: Yue-Ying Lau, Kwo R. Chu, Victor L. Granatstein, Larry R. Barnett
  • Patent number: 4376917
    Abstract: A solid-state cyclotron maser for generating low power (1 watt or less) signals in the submillimeter frequency range (300 GHz-30,000 GHz) includes an accelerating region, a drift region, and a metal grid therebetween. Both regions are formed from semiconductor material, such as indium antimonide, having non-parabolic energy bands. The drift region is a thin disc having metallized outer surfaces, but includes an annular opening in the metal on the front side and a circular opening in the metal on the back side, and is grounded. A grid of metal rings is placed on the annular opening of the drift region. The accelerating region is a hollow cylinder having a metallized front surface. It couples to the drift region for covering the annular opening and the grid. A negative bias voltage is applied to the accelerating region and a magnetic field is applied to the maser at an angle to the axis of the maser. Electrons propagate in spiral trajectories through the accelerating region, grid and drift region.
    Type: Grant
    Filed: June 25, 1980
    Date of Patent: March 15, 1983
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Achintya K. Ganguly, Kenneth L. Davis, Kwo R. Chu
  • Patent number: 4370621
    Abstract: An electron cyclotron maser high-frequency generator/amplifier having a cavity resonator positioned in an axial magnetic field. A spiralling beam of relativistic electrons is injected into the cavity and stimulated emission of radiation by the electrons takes place at the frequency of a wave mode supported by the cavity resonator. The transverse efficiency, defined as the average electron energy loss divided by its initial transverse energy, is maximized by disposing a shaped iron collar about the cavity resonator to provide an axial magnetic field in the cavity resonator whose amplitude increases in the beam direction-of-travel. In an alternative embodiment, the transverse efficiency is maximized by tapering the inner wall of the cavity in the axial direction to provide a wave-mode in the cavity resonator whose electric-field amplitude increases in the beam direction-of-travel.
    Type: Grant
    Filed: March 11, 1980
    Date of Patent: January 25, 1983
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Phillip A. Sprangle, Robert A. Smith, Kwo R. Chu
  • Patent number: 4362968
    Abstract: A slow-wave, cyclotron-type, travelling-wave-tube amplifier in which the m-wave interaction is the result of a Weibel-type instability. The travelling wave is slowed down in its propagation through the waveguide by a dielectric liner located on the inner wall of the waveguide. The bunching mechanism is the result of the V.sub..perp. .times.B.sub..perp. Lorentz force.
    Type: Grant
    Filed: June 24, 1980
    Date of Patent: December 7, 1982
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Kwo R. Chu, Phillip A. Sprangle, Victor L. Granatstein
  • Patent number: 4224576
    Abstract: An apparatus for amplifying coherent radiation at millimeter and submillimeter wavelengths includes the combination of a travelling-wave-tube cyclotron-maser-amplifier structure and a magnetron-injection electron gun. The amplifier structure includes a fast-wave drift tube and an electromagnetic wave launcher within the bore of a superconducting magnet. The magnetron-injection electron gun is also within the bore of the magnet and is coupled to the drift tube. As a travelling wave is launched in a preferred mode in the drift tube, the electron gun injects an annular beam of relativistic electrons having both large energy transverse to the axis of the device and small energy spread into the drift tube so that the electrons gyrate at their cyclotron frequency in orbits about the lines of the axial magnetic field produced by the magnet. The travelling wave is amplified by extracting energy from the relativistic electron beam.
    Type: Grant
    Filed: September 19, 1978
    Date of Patent: September 23, 1980
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Victor L. Granatstein, Phillip Sprangle, Adam T. Drobot, Kwo R. Chu, J. Laurence Safter