Abstract: A connector for making an electrical connection with a mating interface (17) includes a hollow conductor (1) within which is included a member (9) which is relatively movable with respect to the conductor (1). Resilient means (12), which may be a spring, is located between the conductor (1) and member (9). In a first state of the connector, the conductor (1) and member (9) are in a relative position in which the resilient means (12) exerts a force between them urging them together. Following a mechanical connection made between the member (9) and the mating interface (17), the connector is set in a second state in which the force applied by the resilient means (12) takes effect, moving the conductor (1) and member (9) towards one another to make an electrical connection between the conductor (1) and the mating interface (17). This allows a connection to be made with only minimal force and no torque, making it suitable for fragile connections.

Abstract: An electron gun arrangement includes a cathode having a front surface and control grid located in front of it. The control grid is mounted via a cylindrical support on a Kovar mount. The cathode is supported by a cylindrical support mounted on a Kovar support. Ceramic material being located between the two supports. The vacuum envelope within which the electron gun is contained includes the Kovar support and a flexible member with which it makes a vacuum seal, this member being of copper. The copper member is sealed to a ceramic cylinder via metal flanges. The assembly permits the spacing between the cathode and grid to be maintained while the copper member permits thermal expansion to occur to maintain vacuum integrity.

Abstract: In a solar cell arrangement, a generally rectangular solar cell has mutually orthogonal sides in plan view and a third oblique side to them which adjoins them. A protection diode is located in the region bounded by the third side and projections of the first and second sides. The protection diode is electrically connected to the solar cell. Use of the invention enables protection to be provided individual solar cells of a solar cell array without a significant loss in the area occupied by the light sensitive solar cell surfaces.

Abstract: In a catalytic sensor, a bead is located within a can having an aperture in its front surface. The bead is surrounded by thermally insulating material such as glass fiber and a filter material is arranged between the bead and the aperture in the can. This acts to remove H2S or other inhibiting gases before they reach the bead and impair its performance. The thermally insulating material allows the filter material to be included whilst still permitting the bead to be operated at a high temperature.

Abstract: An electron beam tube such as a klystron includes a penultimate resonant cavity (22) located before the output cavity (14). The penultimate resonant cavity (22) is arranged to be inductively coupled, being resonant at a frequency which is slightly greater than a harmonic frequency. This provides increased sharpening of bunches of electrons arriving at the output cavity (14) giving increased efficiency at the output.

Abstract: An electron beam tube includes an electron gun included within a vacuum envelope defined partly by a ceramic cylinder. The ceramic cylinder includes straight sided portions and with an intervening conical section between them. The straight sided portions and form part of two r.f. chokes, being metallized on their inner and outer surfaces and forming a connection with a cavity forming part.

Abstract: In a manufacturing method of a solar cell arrangement, a p-n junction is formed in semiconductor material which is then separated to give a main body and an off-cut. The off-cut is connected in reverse parallel across the main body so as to act as a protection diode for a solar cell which comprises that main body. The off-cut protection diode may be placed adjacent the main body or may alternatively be mounted on the front or rear of the solar cell.

Abstract: An anode structure for a magnetron includes T-shape anode vanes having a radially extensive component and a circumferentially extensive portion, the cylindrical faces of the circumferential portion facing a cathode in the complete magnetron. The use of T-shape vanes increases inductance and hence permits low frequency radiation to be generated without increasing the dimensions of the magnetron compared to those of a conventional magnetron. Also, capacitance is increased to give a further reduction in frequency by using more than two anode straps, and preferably four anode straps at each end of the anode structure. Preferably, the anode structure is incorporated in a magnetron in which a high magnetic field of the order of 500 Gauss for a magnetron operating at 100 MHZ is used. The anode shell itself may form part of the magnetic return path. Other anode vane configuration, for example L-shaped, may be used.

Abstract: A device suitable for switching large currents includes, within a gas filled envelope, an anode, electrodes and a thermionic cathode. Initially the device holds off a voltage until a triggering pulse is applied to an electrode. This cause an electron current to be established between the thermionic cathode and the anode. When the current reaches a sufficiently large value further conduction through the device occurs via current drawn from the surface of the electrode in a cold cathode mode, bypassing the cathode.

Abstract: A switch for switching large currents and large charges includes an anode separated from a cathode with a cylindrical trigger electrode located around the anode and the gap. The cathode is of a metal such as zinc, cadmium, tin or magnesium. During operation, a suitable potential applied to the trigger electrode causes a main discharge to occur between the anode and the cathode.

Abstract: A linear electron beam tube such as an IOT includes an input cavity formed from an inner body portion and an outer body portion which are joined together by a ceramic cylinder. The input cavity surrounds an electron gun and permits electrical connection to be made to the cathode and grid via parts of the inner body portion and. Metallization layers in conjunction with the intervening ceramic material of the cylinder define rf chokes. The construction enables high voltage parts of the arrangement to be insulated from the low voltage outer body portion whilst presenting a low leakage path for r.f.

Abstract: A gas monitor includes an infra-red source enclosed within a housing having inner surfaces which are reflective. Radiation emitted from the source reflects off ellipsoidal surfaces and intermediate planar surfaces to be focussed at a sensor, being reflected five times. Radiation is absorbed by gas within the housing and a comparison of the source intensity and detected intensity gives a measure of the gas concentration. Use of ellipsoidal reflective surfaces directs emitted radiation along a plurality of routes having substantially the same path length, hence giving an accurate measure of the gas concentration with a compact device. In another embodiment, off axis parabolas are used to direct the radiation through the gas.

Abstract: In an imaging apparatus particularly for use in intra-oral dental applications, a solid state imager is arranged to detect X-ray radiation from a source after passing through an object. Prior to irradiation by the source, charge accumulated in the elements of a CCD is clocked from two or more rows into a register such that charges are summed. The register is output via a charge amplifier which sums the charge applied to it to give a relatively large output signal which is amplified and applied to thresholder. Onset of X-ray irradiation is detected when the signal applied to the thresholder exceeds a reference level. A start signal is then transmitted to a control unit to cause image acquisition to begin.

Abstract: A method of identifying an analyte, using a chemical sensor (e.g., a piezoelectric crystal oscillator) which produces an output frequency responsive to different analytes by a characteristic change in the output frequency. The sensor is exposed to a step change (to) in concentration of the analyte and the resulting frequency characteristic measured. An expression for this characteristic is derived consisting of two exponential functions (F, S), one (F) derived from the early part of the frequency characteristic and the other (S) from the latter part. The four parameters (A.sub.2, A.sub.3, A.sub.4, A.sub.5) resulting from the functions so obtained are characteristic of the particular analyte.

Abstract: An actuator for rotation of coupling means such as a loop in a high frequency resonant cavity includes a rotatable member to which the loop is fixed and a rod located adjacent it. The member and rod have interengaging teeth such that when the rod is moved inwardly or outwardly by an operator it causes the member, and hence the loop, to rotate. This is a compact assembly having components which are simple and easy to facilitate. In a preferred embodiment, the rod is located in a groove in the cavity wall.

Abstract: A collector for an electron beam tube includes a ceramic cylinder within which are located rings of a first material, such as copper, and rings of a second material, such as molybdenum, arranged alternately along the longitudinal axis of the cylinder. The ratio of the axial lengths of the rings at the inner surface of the ceramic cylinder is selected so as to provide temperature compensation. The rings of one material surround part of adjacent rings of the other material to confine thermal expansion in a radial direction.

Abstract: In a high frequency transmission arrangement such as that used to deliver microwave energy from a magnetron to a waveguide, a ceramic probe is covered with a non-ceramic dielectric material such as PTFE. This allows the magnetron to operate satisfactorily at low Pressures where arcing would otherwise be expected to occur.

Abstract: An electron beam tube includes a unitary metal cylinder and a plurality of transverse walls located within it which define resonant cavities. As the cylinder is in one piece vacuum joints are only required at the ends of the structure. Drift spaces between the resonant cavities are enclosed within drift tubes which join two adjacent transverse walls. The inner diameter of the tube is stepped to facilitate assembly and accuracy of the structure. In use, an electron beam is generated and interacts with applied r.f. energy to produce amplification of an applied r.f. signal.

Abstract: In high frequency apparatus such as for example an rf resonant cavity or a waveguide, it is often necessary to include a slot to permit a probe or other member to be located in the high frequency region and be moveable along the slot. Sealing means arranged adjacent to the slot and around the probe permits movement of the probe whilst minimising the open aperture area of the slot, hence preventing or reducing leakage through it. In one embodiment of the invention, the sealing means comprises a metallic mesh and in another it includes an elastomer material which is loaded with metallic material and/or carries a metallic mesh.

Abstract: In an output resonant cavity used with a linear electron beam tube such as an IOT, magnetic material is mounted on walls of the cavity and defines annular channels within which coils are located to provide focusing of an electron beam travelling along the axis of a tube located in apertures in the cavity walls. An inner rim locates the electron beam tube with respect to the cavity.