Abstract: A technique for evaluation of high-T.sub.c superconducting films and single crystals is based on measurement of temperature dependence of differential optical reflectivity of high-T.sub.c materials. In the claimed method, specific parameters of the superconducting transition such as the critical temperature, anisotropy of the differential optical reflectivity response, and the part of the optical losses related to sample quality are measured. The apparatus for performing this technique includes pump and probe sources, cooling means for sweeping sample temperature across the critical temperature and polarization controller for controlling a state of polarization of a probe light beam.

Abstract: An X-ray generating source comprising a rotating vacuum envelope with an anode attached thereto and a cathode assembly disposed therewith. The cathode assembly is held stationary within the vacuum envelope exclusively by a magnetic suspension system which comprises a magnet assembly formed by a plurality of electromagnets mounted on two spaced apart rings positioned outside of the envelope and located in the place which is perpendicular to an axis of rotation of the envelope and a magnetic susceptor mounted to the cathode assembly. A plurality of proximity sensors are sensing any displacements of the cathode assembly while a feedback control system being connected to these proximity sensors maintains the proper position of the cathode assembly by changing the value of the magnetic field in gaps between the magnet assembly and the magnetic susceptor.

Abstract: An X-ray tube rotating anode is cooled with a liquid metal functioning as a recirculated heat exchange fluid and/or a metal film in a gap between the anode and a stationary structure. The liquid metal is confined to the gap by (a) a labyrinth having a coating that is not wetted by the liquid, (b) a magnetic structure, or (c) a wick. The liquid metal recirculated through the anode is cooled in a heat exchanger located either outside the tube or in the tube so it is surrounded by the anode. The heat exchanger in the tube includes a mass of metal in thermal contact with the recirculating liquid metal and including numerous passages for a cooling fluid, e.g. water. A high thermal conductivity path is provided between an anode region bombarded by electrons and a central region of the tube where heat is extracted.

Abstract: A self-biased focus X-ray generating tube has a cathode assembly connected by its insert end to a multiplier from outside a vacuum envelope. The multiplier rectifies and multiplies AC power of the filament drive to provide a DC voltage, which is applied to the cathode assembly for pinching the electron beam traveling between the cathode and the anode target of X-ray tube and, as a result, improving the quality of the focal spot.

Abstract: An improved gas pressure gauge is disclosed that extends the linear range of pressure dependent damping to higher pressures by placing a stationary member in very close proximity to the vibrating member. This range of linear dependent damping is also extended to lower pressures by making the vibrating member large in area relative to its small distance from a fixed planar member, which can also serve as its supporting member, by making it vibrate in a direction perpendicular to the fixed planar member, and by making the springs that support the vibrating member from a high Q and conductive material, such as boron doped single crystal silicon. These features for extending the range to higher and lower pressures can be built separately into two independent vibrating elements that can be used individually or in tandem, or they can be built into a single vibrating element that can be made to vibrate in two modes, one parallel and one perpendicular to a fixed member.

Abstract: An ultra high vacuum (UHV) joint is scaled by an elastomer O-ring (7) between adjacent flanges (3,4), fitting in a seal cavity formed by grooves (41,42) in the flange (3,4) surfaces. The groove surfaces (41,42) are highly polished and shaped such that the O-ring (7) conforms to the groove surfaces (41,42) and contacts them substantially entirely when the flanges (3,4) are clamped together. This improved structure significantly reduces the permeation through and the gas leakage around the seal (7). The resulting seal (7) can support a vacuum of 10.sup.-11 torr or better. The conformal-groove geometry of the present invention can be used with seals other than elastomer seals, such as soft metal seals (55,65).

Abstract: In a mass spectrometer leak detector an ion source assembly is disposed in a cavity of a vacuum envelope and is surrounded by a thin removable liner which has means for positioning this liner within the cavity. The liner positioning means limit the thermal contact of the liner with the vacuum envelope and due to heat-radiation relationship of the liner with the ion source the temperature of the ion source region increases and contamination of the ion source decreases.

Abstract: Turbomolecular vacuum pumps having structures which provide increased pumping speed, increased discharge pressure and decreased operating power in comparison with prior art turbomolecular vacuum pumps. In a first embodiment, the stators of one or more axial flow vacuum pumping stages in proximity to the exhaust port of the vacuum pump have progressively lower conductance so that the bulk velocity of the gas being pumped is increased. In a second embodiment, one or more stages near the inlet port of the vacuum pump are provided with a peripheral channel to utilize the centrifugal component of the gas being pumped. In a third embodiment, one or more stages in the vacuum pump are molecular drag stages, each including a disk rotor. One or more pumping channels in the stator adjacent to the upper surface of the disk are connected in series with one or more pumping channels adjacent to the lower surface of the disk.

Abstract: Turbomolecular vacuum pumps having structures which provide increased pumping speed, increased discharge pressure and decreased operating power in comparison with prior art turbomolecular vacuum pumps. In a first embodiment, the stators of one or more axial flow vacuum pumping stages in proximity to the exhaust port of the vacuum pump have progressively lower conductance so that the bulk velocity of the gas being pumped is increased. In a second embodiment, one or more stages near the inlet port of the vacuum pump are provided with a peripheral channel to utilize the centrifugal component of the gas being pumped. In a third embodiment, one or more stages in the vacuum pump are molecular drag stages, each including a disk rotor. One or more pumping channels in the stator adjacent to the upper surface of the disk are connected in series with one or more pumping channels adjacent to the lower surface of the disk.

Abstract: Turbomolecular vacuum pumps having structures which provide increased pumping speed, increased discharge pressure and decreased operating power in comparison with prior art turbomolecular vacuum pumps. In a first embodiment, the stators of one or more axial flow vacuum pumping stages in proximity to the exhaust port of the vacuum pump have progressively lower conductance so that the bulk velocity of the gas being pumped is increased. In a second embodiment, one or more stages near the inlet port of the vacuum pump are provided with a peripheral channel to utilize the centrifugal component of the gas being pumped. In a third embodiment, one or more stages in the vacuum pump are molecular drag stages, each including a disk rotor. One or more pumping channels in the stator adjacent to the upper surface of the disk are connected in series with one or more pumping channels adjacent to the lower surface of the disk.

Abstract: Apparatus equipped for both megavoltage radiotherapy and a diagnostic X-ray source for portal imaging. Both the high energy therapeutic and low energy diagnostic source of radiation are physically located at the same point in apparatus space, and utilize a single moveable target converter that is physically positioned according to the desired use, either therapy or diagnostics.

Abstract: The present invention refers to a pumping stage particularly designed for turbomolecular pumps, having increased compression ratio, and capable of extending the operating range of the turbomolecular pump towards high pressure. The new pumping stage comprises a casing housing, a rotor disk, and a substantially coplanar stator ring. The stator ring consists of two plates connected with each other along their circumferential periphery, thereby defining a region of close tolerance with the opposite surfaces of the rotor. The rotor and stator cooperate to define a tapered, free annular channel having a suction port and a discharge port at the opposite ends of this channel. The channel tapers in a functional, predetermined fashion, having the largest cross-sectional area near the suction port, and converging, according to the rotational direction of the rotor, at the discharge port.

Abstract: The present invention relates to turbomolecular pumps comprising one or more tangential flow pumping stages in addition to axial flow pumping stages, so as to raise the pump exhaust pressure up to the atmospheric pressure, wherein at least one tangential flow pumping stage having a tangential flow pumping channel of improved design. The channel is located between the lateral surface of the rotor disk and the annular inner wall of stator and comprises an upper closure plate provided with suction port and a lower closure plate provided with diskharge port wherein these ports operably coupled to the tangential flow pumping channel. The cross-section area of the channel is enlarged from its periphery portion defined by the lateral surface of the rotor disk to a central portion defined by the upper and lower closure plates.

Abstract: A heater for an indirectly heated vacuum tube cathode is formed of anisotropic pyrolytic graphite in which current passes through the graphite in the "c" direction.

Abstract: An electrostatic chuck for releasably holding a workpiece comprising a substrate formed by a pair of dielectric elements, each being a single crystal, with at least one electrode embedded therebetween, and a voltage source coupled to each electrode. The chuck is preferably fabricated from two substantially planar dielectric members sandwiched around a brazing compound which become electrodes after the assembly is heated and then cooled.

Abstract: An X-ray tube construction of the rotating anode type for reducing acoustic noise and vibration by using granules which are placed loosely within an anode cavity formed between the outer surface of an anode shank and a wall of an anode sleeve in proximity to a bearing journaled to a rotor shaft for rotation of an anode structure.

Abstract: The present invention refers to a pumping stage for turbomolecular pumps comprising a rotor disk (3), integral with a rotating shaft (4) operated by a motor, and a stator disk (1) said stator disk (1), integral with the pump body (2), where the stator disk (1) is a disk whose surface is substantially smooth that can assume, during the evacuation cycle, a bladed configuration, by raising radial sections (5) of the disk surface itself. Raising of radial sections (5) is performed by at least one actuator device (11) controlled, through an electronic control device (12), by a pressure sensor (13) sampling the pressure inside the pump body (2).

Abstract: A standing wave type of microwave linear particle accelerator (40) has a sequence of microwave cavities (42), (43), (44), operated in the standing wave mode, with drift tube conduits (31), (32), (33), between them to permit the passage of a beam of charged particles which are accelerated by the electric fields in each cavity. The first cavity (42) into which the particles enter has a conduit (30) comprising a drift region connected to the particle entrance port (2), outlined by a re-entrant nose (3) extending into the first cavity (42). The drift tube conduit (31) between the first and second cavities (42, 43) has a tapered interior, and the diameter at the upstream end is less than the diameter of the conduit (30) in the re-entrant nose (3) of the first cavity (42). This structure significantly reduces the back bombardment of particles moving backward through the port (2), and increases the efficiency of particle focusing and bunching in the first cavity (42 ).

Abstract: An electronic braking device is provided for an asynchronous motor equipped with magnetic bearings of a type used in turbomolecular pumps. The device comprises a circuit for recovering the kinetic energy of the rotor as it decelerates as a result of a disruption of electric current from an external power means. The device is adapted to convert the rotational kinetic energy of the rotor to an electric current and in order to maintain the support provided by the magnetic bearings.

Abstract: Turbomolecular vacuum pumps having structures which provide increased pumping speed, increased discharge pressure and decreased operating power in comparison with prior art turbomolecular vacuum pumps. In a first embodiment, the stators of one or more axial flow vacuum pumping stages in proximity to the exhaust port of the vacuum pump have progressively lower conductance so that the bulk velocity of the gas being pumped is increased. In a second embodiment, one or more stages near the inlet port of the vacuum pump are provided with a peripheral channel to utilize the centrifugal component of the gas being pumped. In a third embodiment, one or more stages in the vacuum pump are molecular drag stages, each including a disk rotor. One or more pumping channels in the stator adjacent to the upper surface of the disk are connected in series with one or more pumping channels adjacent to the lower surface of the disk.