Varian Associates, Inc.

Communications & Power Industries, Inc.

Erling L Lien

George V Miram

Arthur Karp

Allan W Scott

Richard B Nelson

Heinz Bohlen

An inductive output tube, e.g., a KLYSTRODE, or a klystron, has a substantially hollow electron beam traversing a resonant cavity excited to the TM.sub.0x0 mode, where x is greater than 1.

Hollow beam electron tube having TM.sub.0x0 resonators, where X is

The frequency of an AC signal is multiplied by a factor N, where N is an integer greater than one, by an electron tube including a cathode for emitting an electron beam and a grid including N segments in proximity to the cathode. The grid is biased and coupled to the signal so the beam is formed as N groups of electron bunches during each cycle of the signal. Each segment accelerates one group of bunches for a duration of about 1/N th of each cycle of the signal. Different groups of bunches associated with the different segments are accelerated at phases displaced from each other during each cycle of the signal. In response to the N groups of bunches an output signal having a frequency N times that of the signal is derived.

Frequency multiplier including grid having plural segments

A vacuum tube for amplifying an r.f. signal includes an assembly containing a cathode and grid for current modulating an electron beam derived from the cathode. One of the electrodes of the assembly includes a slow wave structure approximately resonant to the frequency of the signal. A cavity resonant to the frequency of the signal, positioned between the grid and a collector for the beam, is coupled to the beam. In one embodiment, the slow-wave structure is mounted in a support for the grid, while in a second embodiment, the grid is configured as plural, parallel meander lines forming the slow-wave structure. In the latter embodiment, the beam is preferably annular and the meander line geometry, in certain modifications, is adjusted so that there is a relatively small electric-field variation with radius over the portion of the grid through which the annular beam passes. In a further embodiment, the grid is configured as two interlaced spirals, driven by complementary replicas of the r.f. signal so the beam is formed at twice the frequency of the r.f. signal. Focusing electrodes configured as a perforated sheet, contacting the cathode, or as electrodes just downstream of the control grid, or both, collimate ,the beam, whether hollow or not.

Vacuum tube including grid-cathode assembly with resonant slow-wave

A super-power, high voltage klystron includes an output cavity operating in the TM.sub.01x mode, where x is greater than zero.

Klystron resonant cavity operating in TM.sub.01X mode, where X is

A high-frequency amplifier tube includes a grid that responds to an r.f. input signal to current modulate a linear electron beam derived from a cathode. A resonant structure establishes an electric field in a region between the grid and cathode. First and second resonant cavities downstream of the grid in the named order are coupled to the modulated electron beam. The first cavity responds to the r.f. signal to velocity modulate the current-modulated beam. The second cavity is coupled to the current- and velocity-modulated beam for deriving an output signal. An AC connection from a source of the input signal is established to transformer coupling in the first cavity. A phase-shift circuit adjusts the relative phase of the modulation on the beam as it passes through the first cavity and the phase of the r.f. signal as coupled to the first cavity so that fields induced in the cavity by the modulated beam are optimally phased with respect to fields established in the first cavity by the transformer coupling. The phase-shift circuit is connected between the first cavity and the resonant structure or between the second cavity and the resonant structure. A resonant slow-wave circuit is included in the electron-permeable or in an electrically conductive support structure for the grid.

Vacuum tube with an electron beam that is current and velocity-modulated

To suppress spurious oscillations in a helix-type traveling wave tube (TWT), frequency-sensitive loading is produced by a lossy resonant circuit attached to a dielectric support and coupled to the fields of the interaction circuit. The lossy circuit is resonant near the band-edge frequency. It may be a section of delay line with reflective terminations. In one embodiment, it is a metallized pattern on a dielectric rod used to support the helix.

Helix traveling wave tubes with resonant loss

For a grid-controlled electron source to operate at extremely high frequencies, as in planar triodes, the control grid must be situated very close to the emissive cathode. Mechanical and thermal distortions have put minimum limits on grid spacings and hence on the maximum operating frequency of grid-controlled tubes. To overcome these limits the grid structure is formed as a network of web members which are part of a laminated sheet having metal layers bonded to opposite surfaces of an insulating layer. One metal layer is affixed to the emissive surface of a metallic matrix cathode and the other metal layer forms the control grid.

Thermionic electron source with bonded control grid

A grid-controlled electron source comprises an apertured grid spaced in front of a thermionic cathode. Areas of the cathode directly behind the grid conductors are made non-emissive by a bonded surface layer of non-emissive material such as zirconium. On porous metal cathodes impregnated with active emitting material the metal surface may be sealed with a dense layer of inactive metal under the non-emissive layer to prevent chemical reaction of the latter with the emitting material. Methods of depositing the surface layers in the desired pattern include coating the cathode's entire large-scale surface contour, followed by machining small concave dimples into the surface, thereby removing the non-emissive layer from the dimpled surfaces from which small beamlets of electrons are focused between the grid conductors without grid interception. Another method is to mask the desired non-emissive areas with an apertured mask having solid elements registered with the desired positions of the grid conductors. The surface behind the mask apertures is coated with an inactive powder, then the mask is removed and the non-emissive layer or layers deposited in the uncoated, previously masked paths. Lastly, the inactive powder is removed, uncovering the emissive surface areas.

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Los Altos, CA, United States of America

Erling L Lien