Anodes in X-ray tubes

Solid solution alloys of W and Re in the range of 2-25 wt % Re play an important role as rotating anodes in X-ray tubes for diagnostic purposes and as wires for thermocouples. These materials are produced by powder metallurgical techniques. Inappropriate mixing of the two powder components may result in a partial a-phase formation, which is undesirable due to embrittlement. 

Gallium is the only metal, besides mercury, cesium and rubidium, that can be liquid near room temperatures. The temperature range for the molten phase is very wide, 30 to 2403°C. This makes the metal usable in high-temperature thermometers. Turn-able anodes in X-ray tubes may also be mounted in liquid gallium. 

Use Getter alloys in vacuum tubes, deoxidizer for copper, Frary s metal, lubricant for anode rotors in X-ray tubes, spark-plug alloys. 

Bario Barium Baryum EINECS 231-149-1 HSDB 4481 UN1400. Alkaline-earth element Alloys in vacuum tubes, deoxidizer for copper, lubricant for anode rotors in x-ray tubes, spark-plug alloys, mp = 725 bp = 1640 d = 3.51 reacts with H2O, producing H2. Atomergic Chemetals Degussa AG Noah Cham. Sigma-Aldrich Fine Chem. 

OTHER COMMENTS used as getter alloys in vacuum tubes used as a lubricant for anode rotors in x-ray tubes and spark-plug alloys used as a carrier for radium. 

The X-ray source is a 30 kV side-window X-ray tube with a rhodium anode target. X-ray tube voltage and emission current are set in order to yield source X-rays with energy above 25 keV and approximately 30 000 cps at the detector. For these tests the following X-ray tube parameters were used tube voltage of 27 kV and emission current of 75 uA. To obtain a more monochromatic X-ray source in the range 20-30 keV, a palladium filter is mounted over the X-ray tube. This gives source X-rays primarily at 21 keV, the K-line emission of palladium. 

It can be seen from Eq. (3.7) that the analyte line intensity excited by the continuum is proportional to the atomic number of the anode. Thus, higher atomic number anodes would be expected to yield higher sensitivities. Unfortunately this is not always the case. In high-power, grounded-anode, sealed x-ray tubes, the higher the atomic number of the anode, the greater is the fraction of incident electrons that are scattered in the direction of the x-ray tube window. This in turn requires a relatively thick window (perhaps 500- to 1000-jim beryllium) to dissipate the... 

Other applications are rhenium-tungsten alloys in X-ray tubes and rotating X-ray anodes. Rhenium-molybdenum alloys are superconductors at a temperature of 10 K. 

In X-ray tubes, the X-rays are produced by the bombardment of matter with accelerated electrons. The X-ray tubes are built as a vacuum-sealed metal glass cylinder. The electrons are emitted from a heated tungsten filament which serves as the cathode and are accelerated by a high voltage applied between the filament and a metal anode. Two effects can occur if the accelerated electrons interact with the atoms of... 

Uses Alloys in vacuum tubes deoxidizer for copper lubricant for anode rotors in x-ray tubes spark-plug alloys in nuclear readors electronic tubes additive in lubricating oils mfg. of pyrotechnics and explosives tanning and finishing leather mordant for fabrics and dyes eledroplating aluminum refining rubber mfg. prod, of paints and enamels Regulatory Canada DSL... 

It is easy to notice, that the protection against a short-circuit failure in the X-ray tube circuit implements due to the "soft" outer characteristic of the apparatus main circuit. The overvoltage protection at emergencies in the control system happens due to the redistribution of the magnetie flow, created by power winding I, between the 3,6 control yokes. Therefore the voltage on the X-ray apparatus anode drops approximately two times. 

X-ray tubes are used in a broad variety of technical applications the classical application certainly is the radiographic inspection. For the penetration of high-Z materials, relatively high power is required. This lead to the development of X-ray tubes for laboratory and field use of voltages up to 450 kV and cp power up to 4,5 kW. Because of design, performance and reliability reasons, most of these maximum power stationary anode tubes are today made in metal-ceramic technology. 

X-Ray Emission and Fluorescence. X-ray analysis by direct emission foUowing electron excitation is of Hmited usefulness because of inconveniences in making the sample the anode of an x-ray tube. An important exception is the x-ray microphobe (275), in which an electron beam focused to - 1 fim diameter excites characteristic x-rays from a small sample area. Surface corrosion, grain boundaries, and inclusions in alloys can be studied with detectabiHty Hmits of -- 10 g (see Surface and interface analysis). 

Unlike for synchrotron radiation, the maximum iatensity of x-rays from an x-ray tube is limited by how fast heat can be removed from the target to prevent its melting. In a conventional sealed tube, the target is stationary, relatively small, and must be continually cooled with water. In a rotating anode tube, the target is larger and is continually rotated so that the heat can be distributed over a larger surface. With such a tube the amount of heat, and hence. 

Barium improves the performance of lead ahoy grids of acid batteries (see Batteries) (34). In the form of thin films, barium has been found to be a good high temperature lubricant on the rotors of anodes operating at 3500 rpm ia vacuum x-ray tubes (35). 

Benzene, benzene-t/i, CFCI3 and CF3CCI3 were obtained commercially and were not further purified. Solutions of c a 0.3 - 1 volume % of benzene in CFCI3 were prepared in suprasil quartz tubes of 4 mm outer diameter on a vacuum line. The samples were degassed and sealed under vacuum (< 10-4 -porr). Polycrystalline samples were prepared by rapid freezing in liquid nitrogen. The samples were irradiated at 77 K for 5 minutes at an approximate dose rate of 250 G/min. using the radiation from an X-ray tube with a W anode operated at 70 kV and 20 mA. 

The diffractometer has gradually evolved in terms of maximum power of sealed X-ray tubes, rotating anodes, new X-ray optics, better detector efficiency, position-sensitive detection and, lately, real-time multiple-strip (RTMS) fast X-ray detection, which replaces a single detector by an integrated array of parallel detectors to provide an up to 100-fold increase in efficiency compared with traditional detectors without compromise on resolution. Time-resolved powder diffraction is... 

The heavily stressed anode in high-performance X-ray tubes is coated with a rhenium-tungsten alloy. 

A variant of the typical X-ray tube described above is the rotating anode, which is capable of generating much higher intensities. Although rotating anode sources can and have been used in EXAFS experiments, the intensities are of such magnitude that data acquisition for extended periods of time is required and their application is furthermore limited to bulk samples. 

The maximum power of a conventional X-ray tube is 2.4 kW for broad focus (approx.. 2x 12 mm focal spot size). Modern rotating anodes consume 18 kW and deliver fine focus (approx.. 0.1 x 1 mm focal spot size). Most important for high intensity is not the power consumption, but the product of focal spot power density and focal spot size or, more accurately, the flux on the sample measured in photons/s (cf. Sect. 7.6). 

The electrochemical cell used by Flcischmann and co-workers (1986) employing the Bragg configuration is shown in Figure 2.67(b). The source is a copper anode X-ray tube employing a Ni filter to select out the Cu Ka line the detector is a PS PD. 

X-ray tube—A metal anode is bombarded with high-energy electrons causing inner-shell electrons to be ejected and replaced by higher shell electrons. The loss in energy of these electrons as they drop to the lower levels is on the order of the energy of x-rays, and x-rays are emitted. 

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