Abstract: In a gyrotron microwave tube, electromagnetic leakage through beam-transmitting drift tubes is greatly reduced by making the diameter of the drift tubes in centimeters less than 8.8 divided by f where f is the operating frequency in gigahertz.

Abstract: High-power linear-beam electron tubes require an extended uniform magnetic field to focus their beam in an elongated cylinder. When permanent magnets are used to energize the magnet structure, there is inevitably a leakage field outside the main flux-return path. The leakage field can refocus the beam in the tube's collector, damaging it. When the collector has air-cooling fins, it is not practical to shield it completely with magnetic material. In the invention, the leakage field is reduced by making the energizing magnet at the collector end axially magnetized and the magnet at the cathode end radially magnetized. Also, a shield around the outside of the fins may be added.

Abstract: A window assembly for ridged waveguide has a slab of dielectric extending clear across the waveguide cross-section. The slab may be perpendicular to the waveguide or cross it at an angle. The waveguide ridge or ridges are notched so that the dielectric slab passes through the notch. Inductive tuning posts may be added to make a broadband match. The window assembly has an excellent match over more than an octave frequency range.

Abstract: In an image converter tube, the brightness contrast of the output picture is reduced by light which is internally reflected at the surfaces of the window through which the image is viewed. The contrast can be improved by making the window partially light-absorbing, at the expense of a reduction in the overall optical gain. This gain varies considerably from tube to tube. By adding an external filter on the output window, the transmission of the filter can be chosen for each tube to provide the minimum acceptable gain and thus the maximum obtainable contrast.

Abstract: A filter for megavolt X rays has an absorbing member shaped to provide greater thickness for rays in the direction of higher intensity, e.g., the axis of the electron beam. A second absorbing member of a material of different atomic number is shaped to provide greater thickness for rays in the direction of higher photon energy, e.g., said axis. By selecting the combined shapes, both the intensity and the effective photon energy can be equalized over the field of radiation. Thin removable shims may be added for further adjustment. A neutron filter may also be added.

Abstract: For conducting very high microwave power at very high frequencies, circular waveguide transmitting a circular-electric-field mode is used. The vacuum-tight window of an electron tube is often the element with lowest power-handling capability. The inventive window has two dielectric plates with a space between them. There is a gap in the waveguide inner wall through which a dielectric fluid is circulated between the plates to cool them. The gap leads to a region containing wave-absorbing material such as water to absorb modes other than the circular-electric-field mode.

Abstract: In a high-power grid-controlled electron tube, a common anode receives electrons from a modular electron source having a common support structure to which are attached a plurality of modules. Each module has at least one cathode and grid mounted on a base which is individually attached to the support structure. The grids are approximately flat sheets of carbon with apertures to pass the electrons. Pyrolytic graphite is a preferred grid material.

Abstract: A gas ballast device for an oil sealed mechanical rotary vane vacuum pump prevents vapor condensation in the outlet port region of the low vacuum stage of the pump as a vane cyclically approaches the outlet port, whereby molecules of condensed vapor in the oil do not flow back to the inlet port of the low vacuum stage through the oil seal between the inlet and outlet ports. A flow path for atmospheric air leading to the outlet port region includes a tortuous, constricted fluid passageway. An outlet passage connecting the tortuous, constricted fluid passageway to the outlet port region is positioned so that an orifice thereof into the outlet port region is filled with and sealed by oil except during a small portion of each vane cycle immediately after the vane passes the orifice, whereby no movement of mechanical parts is employed to control air flow in response to the cyclical movement of the vanes past the orifice.

Abstract: Secondary electrons emitted from an electron-collecting electrode of a vacuum tube degrade the performance. Emission of high-speed secondaries is reduced by coating the electron-collecting surface with a material of low atomic number. Emission of low-speed secondaries is a less predictable function of the surface material and structure. The invention comprises a coating of aluminum boride or similar substance, which has low secondary emission and is also easy to outgas.

Abstract: An electrical-to-acoustic wave transducer contains an array of piezoelectric elements connected to wave-delay circuits to generate a directed acoustic beam and to receive a similarly directed, reflected beam. The distance of a reflecting object is sensed by the time delay of the reflected wave. The apparatus is adapted to sense reflections from both the Fresnel region and the far-field of the array. During the time when reflections from nearby objects in the Fresnel region are received, the effective aperture of the array is reduced by disconnecting elements near its extremities or reducing their gain, producing a narrower beam for improved angular resolution.

Abstract: A dense film of silicon nitride is deposited by a plasma discharge in a vapor of azidotrimethylsilane (AZS) (CH.sub.3).sub.3 SiN.sub.3. AZS is less reactive and easier to handle than the previously used silane SiH.sub.4. The resulting film is more stable chemically than the silicon nitride produced by other processes. It is useful for protective and anti-reflective coatings, for insulating, and for masking, particularly on semiconductive devices.

Abstract: 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.

Abstract: An improved field-effect transistor is provided by forming the conducting channel boundary opposite the gate electrode as a heterojunction. For example a GaAs conducting channel may be bounded by an AlGaAs layer. The conduction electrons can penetrate the boundary very little and are constrained to the channel layer having good transport properties. The output conductance is reduced and the transconductance increased.

Abstract: An oscillator for very high microwave or millimeterwave frequencies employs a pair of negative-resistance semiconductive devices, each mounted in its own resonant cavity. The two cavities are coupled together by an iris in their common wall. An output waveguide is coupled symmetrically to both sides of the common wall to load both cavities equally. An adjustable mode-control element projects into the cavity to the near vicinity of one of the devices to induce the oscillator to start in the desired mode. Additional dielectric or metallic tuners in the cavities provide a wide variation of frequency.

Abstract: A traveling-wave amplifier tube adapted for use as a booster of transmitted signals has very small internal circuit attenuation so that it may be used without an electron beam as a transparent, passive path for low transmitter power. When the booster tube's beam is excited, the signal is amplified about 10dB. Upper bandedge instabilities in the lossless tube are inhibited by a lower cutoff frequency of the circuit near the output end than near the input end, so that bandedge power can flow both ways out of the large-signal output end.

Abstract: A coaxial line has a conductive surrounding shield connected from a first to a second point thereon. The outer conductor of the coaxial line shield is discontinuous at an intermediate point inside the shield so that it has two intermediate ends or terminals therein. A radio frequency signal applied to one end of the electrically unbalanced coaxial line will be supplied on the balanced intermediate terminals through a broadband transformation by the coaxial line with its shield, which constitutes a balun (balancing transformer). The length of each part of the coaxial line, from each intermediate terminal to the first and second points, is preferably one-quarter wavelength at the center frequency of an applied frequency band.The coaxial line may be used with another coaxial line mounted orthogonally to the first line, with both lines mounted within a common enclosure or shield, thereby to provide a dual balun.

Abstract: The device is a translucent plastic mask or overlay which fits over the keyboard of the computer input/output station to label the keys with their functions according to the selected mode of operation. A projecting portion along one of the edges of the mask extends into a slot adjacent the keyboard where a series of code segments forms an optical code which is read by a corresponding series of lamp and photocell pairs to provide the computer with the information to cause its mode of operation to correspond with the keyboard legends.

Abstract: A body of p-type indium phosphide, which was heretofore difficult to contact in a reliable low resistance manner, is ohmically contacted by an alloy contact of bismuth with preferably 2% zinc. The alloy contact is effected by placing a small pellet of the Bi-Zn alloy on the surface of the p-type InP body and then alloying at a preferred temperature of 360.degree. C for 20 seconds.

Abstract: Travelling wave tubes designed to operate interchangeably at low power cw and high pulsed power have grids to gate the pulses and to switch the peak beam current between two values. To preserve optimum beam-focus conditions, the beam diameter should be simultaneously switched. A grid covering the central region of a concave cathode draws the low-current, small beam for cw operation or the central part of a large pulsed beam. A second grid controls added pulsed emission from the surrounding annular region of te cathode. To provide the proper ratio of beam sizes and uniform cathode loading, the cathode has radially varying radius of curvature. A hyperboloid of revolution is a good shape.

Abstract: A cell for converting received light energy to electrical energy comprises, in the simplest embodiment, four layers of differing types of semiconductive material stacked so as to form three opposite conductivity junctions. The outer two, "active", junctions are formed of confronting layers with matched lattice constants so as to provide a plurality of energy converters. The center, "connective", junction is formed by two confronting intermediate layers which have purposely mismatched lattice constants so as to provide a lattice defect site surrounding the center junction. Majority carriers (electrons and holes) will recombine at the lattice defects. This will cause the connective junction, although of apparently reverse-biased opposite conductivity type layers, to act as a low resistance ohmic connection or substantial short circuit so as to connect the energy converting portions in series.