Other

USA As Represented by Secretary of the Navy

University of Utah Research Foundation

Larry R Barnett

Yue-Ying Lau

J Mark Baird

Kwo R Chu

Victor L Granatstein

Shih Han Chen

Young-Min Shin

Kwo Ray Chu

Richard W Grow

Tze T Yang

Han Y Chen

Yi C Tsai

Michael B Kenny

Yih S Yeh

Chaoen Wang

Trine Y Dawn

A compact magnet system for use in a high-power microwave tube includes an electromagnetic coil surrounded on three sides by permanent magnets. More particularly, constituent components include a first tubular retaining member; the electromagnetic coil that fits within the first tubular retaining member and that has a central cavity; first permanent magnets positioned to extend radially from the central cavity so that like poles of the first permanent magnets wrap around the central cavity along a first side of the solenoid coil; and second permanent magnets positioned to extend radially from the central cavity so that opposite poles to the first permanent magnets wrap around the central axis along the second side of the solenoid coil. Optional added components include two sets of permanent magnets, one set on each side of the coil and a pole piece located adjacent to an end of the first tubular retaining member.

Compact magnet system for a high-power millimeter-wave gyrotron

A two-dimensional circuit for a traveling-wave tube for millimeter and sub-millimeter electromagnetic waves synchronously interacts with an electron beam in a vacuum electronic microwave amplifier or oscillator. The circuit is a solid body having a length along the tube axis. The solid body has an electrically conductive top section and an electrically conductive bottom section. The top section is configured with a plurality of vertical vanes having a width and height and configured parallel to each other. The bottom section is similarly configured such that when the circuit is viewed in cross section along the length, the vanes on the bottom section are staggered with respect to the vanes on the top section. The top section and the bottom section are separated from each other to define a tunnel through the solid body along the length.

Traveling-wave tube 2D slow wave circuit

A magnet configuration for a power microwave tube with a resonant cavity comprises a permanent magnet () with an axis-aligned through-bore () of sufficient size to contain the resonant cavity. The permanent magnet has an inner chamber () that is centered on the axis () with opposite magnet poles aligned along the axis. The magnet configuration further comprises an electromagnet coil () fitting in the chamber and encircling the axis such that the coil produces a magnetic field that reinforces the magnetic field from the permanent magnet. An optional protrusion () spanning the through-bore narrows an air gap between the poles. The method provides a magnetic field in a power microwave generator by combining a permanent magnet with an electromagnet in accordance with the magnet configuration and energizes the electromagnetic coil, which may be by pulsing the coil current.

Electro-permanent magnet for power microwave tubes

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. The mechanical tunability feature provides the MIG with an extra degree of freedom for the optimization of the beam quality, it provides the versatility of operation in a much greater parameter space, it can be used to compensate for machining errors and thermal deformations, and it can provide tunability for single anode MIGs.

Mechanically tunable magnetron injection gun (MIG)

A gas ionization type vacuum gauge for testing the internal vacuum levels to below 10.sup.-6 torr is disclosed which uses a multipactor discharge means as the source for the electron current used to ionize residual gas molecules. The invention comprises an RF field enhancing cavity which can be constructed of high-vacuum-compatible materials, able to withstand bake-out microwave temperatures and a negatively biased ion collection wave, wire, or grid. A simple ceramic RF feed-through permits simple and noninvasive pressure measurements. The device can be made much smaller than conventional gauges.

Multipactor pressure gauge for use as a noninvasive vacuum tube sensor

A coupler employing two similar sections of waveguide which extend coliney in longitudinal succession. Adjacent ends of the guide sections are spaced apart to form a gap in the boundary of the sections. A third section of waveguide is disposed external to and coaxial with at least a part of each of the two waveguide sections to provide a boundary surrounding the gap. Electromagnetic energy propagating down one of the two similar sections of waveguide in a first mode and entering the gap is converted partly to a plurality of other modes. The converted energy is reconverted to the first mode upon reaching the other of the two similar sections of waveguide. The electric field pattern exciting the section of waveguide at the end of the gap and propagating down it is exclusively in the first mode. The cutoff-determining dimensions of the third section of waveguide and the gap separation are determined from the condition that the phase relationships between the modes at the end of the gap be the same, to within an integral multiple of 2.pi., as what they were at the beginning of the gap, to insure complete transfer of power between the two similar sections of waveguide.

Waveguide coupler using three or more wave modes

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.

Wide-band distributed rf coupler

An RF cyclotron maser type traveling-wave amplifier including an integral active circulator. The amplifier includes a tapered interaction waveguide having a cross-section which gradually increases from a small first end to a larger second end thereof. The waveguide is capable of supporting first and second orthogonal polarization modes therein with approximately the same propagation characteristics for the two modes. A beam of mildly relativistic electrons having helical electron motion is directed into the small first end to axially propagate within the waveguide toward the larger second end. A tapered magnetic field is generated within the waveguide in a direction approximately parallel to the axis of the waveguide. The magnetic field is profiled to near grazing interaction with the second polarization mode of the waveguide. An input electromagnetic wave in the first polarization mode is launched into the larger second end of the waveguide to propagate toward the first end thereof. The input wave is reflected by the constriction of the tapered waveguide to co-propagate with the electron beam in the waveguide. The reflected input wave additionally excites energy in the second mode which also co-propagates with the electron beam. The first and second modes are amplified by the electron beam; the second polarization mode being amplified to a greater extent than the first mode. The two orthogonal modes are easily separated to provide input and output ports for the amplifier.

Active circulator gyrotron traveling-wave amplifier

A gyromagnetron amplifier for radiation at millimeter wavelengths comprising a tapered waveguide tube with longitudinally running vanes in the walls of the tube with the number of vanes chosen to coincide with a desired cyclotron harmonic frequency to be amplified. A beam of spiralling mildly relativistic electrons with an energy of 100 keV or less is directed into the small end of the tapered waveguide tube. A tapered axial magnetic field is set up within the waveguide tube with a low value appropriate to the amplification of a cyclotron harmonic frequency. An electromagnetic wave to be amplified is launched into the waveguide tube to co-propagate and be amplified by the spiralling electron beam. This device is characterized by a wide bandwidth, a low operating magnetic field, a relatively low operating beam voltage, with high power, and the capability of continuous wave operation.

Gyromagnetron amplifier

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 direction, the .perp. subscript designates the direction perpendicular to this axial direction, and the o subscript represents those quantities at the entrance point for the electron beam into the waveguide. This device has been found experimentally to have negligible launching loss and low sensitivity to electron velocity spread.

Wide-band gyrotron traveling-wave amplifier

A cyclotron maser microwave amplifier and oscillator which utilizes non-relativistic electrons in cyclotron motion and a spatially nonlinear electrostatic field which is produced by the space charge of the electrons. The term 'spatially nonlinear electrostatic field' encompasses static electric fields whose magnitude can be described mathematically as varying in a nonlinear manner as a function of position in one or more directions. As taught by U.S. Pat. No. 4,253,068 of Feb. 24, 1981, 'Cyclotron Maser Using a Spatially Nonlinear Electrostatic Field', completely non-relativistic electrons may be used in principle for which phase bunching will occur due to the nonlinear motions induced by the electrostatic field, resulting in stimulated emission of cyclotron radiation for use in a microwave amplifier or oscillator. U.S. Pat. No. 4,253,068 teaches that appropriate nonlinear electrostatic fields can be established by suitably shaped electrodes and a low charge density electron beam. The present application teaches that appropriate nonlinear electrostatic fields can be produced by the self fields of the space charge of the electron beam. Resulting amplifiers and oscillators are here named barnetron amplifiers and oscillators. An electron gun which produces an annular electron beam with components of velocity perpendicular and parallel to an axial magnetic field.

Barnetron microwave amplifiers and oscillators

A rectangular waveguide to circular waveguide coupler and vice versa. The upler includes a first section of circular waveguide spaced by a gap from a reflective-plane conducting wall, the latter having a hole for passage of an electron beam if the coupler is used in a traveling wave tube, and a second section of circular waveguide disposed external to, and coaxial with, at least a portion of the first waveguide section and extending to the wall to provide a conductive boundary surrounding the gap. The region between the first and second waveguide sections forms an input port of the coupler; the first waveguide section forms the output port of the coupler. Electromagnetic waves in a TE.sub.01 coaxial waveguide mode are applied to the input port from a rectangular waveguide supporting the dominant TE.sub.10 mode. The second waveguide section has a cut-off determining dimension r.sub.e proportioned to support both the TE.sub.01 and TE.sub.02 circular electric modes in the region of the gap at the frequency of the applied waves. The first waveguide section has cut-off determining dimensions r.sub.1 proportioned to support the circular electric TE.sub.01 mode to the exclusion of all higher-numbered circular electric modes at the frequency of the applied waves.

Waveguide mode coupler for use with gyrotron traveling-wave amplifiers

A cyclotron maser microwave amplifier or oscillator which utilizes non-relativistic electrons (or other charged particles) in cyclotron motion and a spatially nonlinear electrostatic field. The term 'spatially nonlinear electrostatic field' encompasses static electric fields whose magnitude can be described mathematically as varying in a nonlinear manner as a function of position in one or more directions. Completely non-relativistic electrons of very low energy may be used in principle for which phase bunching will occur due to the nonlinear motions (induced by the electrostatic field) resulting in stimulated emission of cyclotron radiation for use in the amplifier or oscillator. This is in complete contrast to the relativistic cyclotron maser (Hirschfield, U.S. Pat. No. 3,398,376) which required the electrons to be acting under the relativistic effect of the electron mass (and hence cyclotron frequency) being a function of its energy to produce the necessary phase bunching and resulting stimulated emission. This new means of cyclotron maser action, in principle, is induced by a variety of spatially nonlinear electrostatic fields.

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Manassas, VA, United States of America

Larry R Barnett