Glass Vacuum Research Articles

Surface temperature determination in surface analytic systems by infrared optical pyrometry

An IR pyrometric technique for measuring the surface temperatures of metal specimens in an ultrahigh-vacuum analytic chamber is described and demonstrated. The experimental setup comprises a commercial IR microscope with a long-working-distance right-angle objective (focal spot diameter 1 mm at 53 cm), a metal-coated glass vacuum chamber with a Ta-mesh-covered quartz viewport, an Mo specimen stub with an internal heating element, and a Ta disk test specimen with a flat side coated with a high-emissivity graphite film. The results of an initial calibration test are presented graphically and briefly characterized. The measurement error at 450 C is found to be less than 10 C.

A comparison between RF-driven single and double cathode structures

Experimental results are presented for the electron density, bias voltage, and dark space size surrounding a 18-cm-diameter cathode situated in the centre of a 30-cm-diameter, 30-cm-long glass vacuum chamber, containing low-pressure argon. The cathode is a single aluminium plate to which can be added another plate situated at various distances from the first and electrically connected to it. The effect of the second cathode is to dramatically reduce the self-bias on the driven cathode and considerably increase the luminosity: The plasma density increases but at a significantly smaller rate.

16:9 aspect ratio 38V-high resolution trinitron CRT for HDTV

The development and characteristics of a 38-in (vertical) tube for high-definition television (HDTV) are discussed. Design details are given for the glass vacuum tube, the aperture grill and phosphor screen, and the electron gun and deflection yoke. The characteristics of the cathode-ray tube and display monitor are examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Vacuum brazing of titanium using eddy current heating

The vacuum brazing of titanium is not particularly easy in normal vacuum furnaces: the metal oxidises readily at high temperature and so a high vacuum is required. An alternative approach is to have the workpiece inside a glass vacuum chamber and to heat it with eddy currents induced by external coils. Thus the heating is only local and a better pressure is obtained. Our experience of brazing small, but complex, titanium assemblies by this method will be discribed.

N-halogeno compounds. Part 9. N-Fluoroquinuclidinium fluoride—a new electrophilic fluorinating agent

N-Fluoroquinuclidinium fluoride, prepared in high yield by treatment of a cold, dilute solution of quinuclidine in trichlorofluoromethane with fluorine at low pressure in a specially designed, virtually all glass vacuum system, acts as a site-selective electrophilic fluorinating agent towards carbanionic substrates [PhCNa(CO2Et)2→ PhCF(CO2Et)2; Me2CLiNO2→ Me2CFNO2; RMgX → RF (R = Ph, X = Br; R = c-C6H11, X = Cl); [graphic omitted]H2→ [graphic omitted]HF; PhSiCl3/F–(in situ)→ PhF].

Gas-phase hydrolysis of proteins and peptides

A simplified gas-phase hydrolysis procedure for proteins and peptides is described. The apparatus consists of a glass vacuum desiccator, a ceramic plate, and a Teflon ring. The method was shown to give reproducible compositions for hydrolysis of human serum albumin and microanalysis of α-melanocyte stimulating hormone including the quantitation of as little as one residue of tryptophan. It minimizes sample handling and allows for the simultaneous hydrolysis of a large number of samples.

Preparation of CO2 from blood and protein-bound amino acid carboxyl groups for quantification and 13C-isotope measurements.

Measurements of protein and amino acid metabolism in man using stable isotopes and selected ion monitoring gas chromatographic/mass spectrometric techniques are limited by the requirement of relatively high levels of labelling for adequate precision (greater than 0.05 at % excess). We describe here a means of extending the scope of such studies by measurement of lower levels of enrichment achieved in gaseous CO2 derived from whole blood or protein-bound amino acids following the administration of tracer amounts of appropriately labelled substrates. Construction and operation of a novel glass vacuum line required for this work are described in detail and specific applications relevant to clinical investigations are outlined. Measurements of both the total amount of CO2 and its 13C enrichment are performed in an isotope-ratio mass spectrometer which provides acceptable levels of accuracy and reproducibility for both measurements (+/- 0.1% and +/- 0.0001 at % excess respectively).

Development of a Sodium Vapor Pressure Meter Using Beta-Alumina Ceramics

A program was carried out to develop a sodium vapor pressure measuring system using beta-alumina ceramics for use in developing sodium vapor traps and monitoring sodium mist in cover gas for fast breeder reactors (FBRs) and test facilities. The sensor device was tested in a vacuum glass capsule. Its output agreed well with theoretical results. Moreover, it proved to have the capability of measuring a lower vapor pressure near 10−5 Torr without any calibrations.The measuring system, consisting of a beta-alumina sensor device, gas circulating pump, gas heater, and mist trap, is applicable to FBR plants and test facilities that contain much sodium mist and to a transient monitoring system. This system was tested in an isothermal sodium vapor circulation test loop under conditions involving much sodium mist.

High voltage, helium flow cryostat for solid insulator surface strength investigations in a vacuum

A high voltage, helium flow cryostat comprising two metal cryogenic liquid containers and a glass vacuum chamber is presented. The simplicity of the cryostat's construction is convenient in that it can be used in different types of high voltage investigations in a vacuum, in the range from the liquid helium temperature to the room temperature.

An indirectly cooled 8 T solenoid built up from an Nb - Ti filamentary cable

A solenoid with a length of 290 mm and a free bore of 240 mm was built for testing model conductors. The multifilamentary cable has a graded Nb-Ti cross-section corresponding to the decreasing magnetic field from inside to outside of the winding. The coil is wound on a glass epoxy former and vacuum impregnated. During operation in the SULTAN Test facility at SIN, Villigen, the coil is forced flow cooled with supercritical helium through a cooling pipe on the surface, At a current of 660 A the coil creates a field of 7.2 T in the test volume.

A pneumatically operated high vacuum glass tap

A pneumatically operated high vacuum glass tap

Current generation due to a travelling lower hybrid wave excited by helical antennas

Abstract A toroidal plasma current was observed to be driven well inside the plasma by travelling lower hybrid waves excited with helical antennas wound around a glass vacuum chamber.

Study of turbulent heating effects in the high beta tokamak Torus II

Torus II is a rectangular cross section, high beta tokamak which has a glass vacuum vessel (aspect ratio of 3.5) filled with 12 mTorr helium. The plasma is heated by turbulent poloidal skin currents, induced by a fast (τr=1.7 μsec) reversal of the toroidal field which converts a toroidal Z pinch plasma into a tokamak plasma. By using the broadening of He II 4686 Å and impurity lines, it is found that strong turbulence (Ẽ⩽30 kV/cm microscopic fields at frequency ⩽ωpi≈3×1010 rad/sec) is induced during the heating phase. The turbulent Ẽ fields maximize in the region of maximum induced poloidal skin current (α∂Bφ/∂r). The resulting high beta tokamak plasma, with &amp;lt;β≳v≈10% and ne≈1015 cm−3, has an initially peaked radial temperature profile with Ti≈180 eV at the plasma center. A few microseconds later, the He II-determined ion temperature becomes nearly spatially flat at Ti≈75 eV, and then decreases slowly in time. Impurity ion lines indicated a temperature approximately 100 eV greater than He II. All line profiles indicated a poloidal circulation with Er×Bφ characteristics and Er≈100 V/cm radially inward. The spectroscopy was done in the visible region using a six channel polychrometer having a 0.2 Å resolution, which is capable of radial scans of the plasma. The details of turbulent heating derived from the analysis of ion line profiles are presented.

Tritium practices past and present

History of the production and use of tritium, as well as handling techniques, are reviewed. Handling techniques first used at Lawrence Livermore National Laboratory made use of glass vacuum systems and relatively crude ion chambers for monitoring airborne activity. The first use of inert atmosphere glove boxes demonstrated that uptake through the skin could be a serious personnel exposure problem. Growing environmental concerns in the early 1970's resulted in the implementation by the Atomic Energy Commission of a new criteria to limit atmospheric tritium releases to levels as low as practicable. An important result of the new criteria was the development of containment and recovery systems to capture tritium rather than vent it to the atmosphere. The Sandia National Laboratories, Livermore, Tritium Research Laboratory containment and decontamination systems are presented as a typical example of this technology. The application of computers to control systems is expected to provide the greatest potential for change in future tritium handling practices.

Magnetron-sputtered metal carbide solar selective absorbing surfaces

A range of magnetron reactively sputtered metal carbide interference filters has been deposited onto sputtered copper on glass substrates and aged in vacuum at elevated temperature. These films show considerable promise as selective surfaces for incorporation in all glass vacuum insulated solar energy collectors. Surfaces produced by depositing homogeneous metal carbide films have solar absorptances α∠80% and emittances ε∠2.0% at 300 K. Solar absorptances above 90% and emittances 3.0%–4.0% at 300 K are obtained for multilayer metal carbide films fabricated by varying the reactive gas flow rate in steps during the deposition. Ageing experiments show that the reflectances of the multilayer films alter due to interdiffusion between the layers, resulting in a slow degradation of solar absorptance. Some diffusion coefficients for carbon in stainless steel and titanium films have been evaluated. Surfaces fabricated using chromium, molybdenum, and stainless steel carbides are superior to titanium carbide surfaces. Magnetron sputtering technology offers the possibility of more rapid and efficient deposition of these selective surfaces compared with the high pressure diode deposition technique utilized in previous work.

Vacuum compatibility of machinable glass ceramics

The thermal outgassing and helium permeation characteristics of Code 9658 machinable glass–ceramic are discussed. Up to 600° C, it is shown that this material can be treated like glass vacuum system components. The quantities of outgassing constituents under vacuum conditions are given and the need for vacuum baking freshly machined material is demonstrated. Although the material can be used up to 1000° C, between 600° and 1000° C some fluorine evolution from the material takes place and could present a corrosion problem to some systems. Helium permeability of this material is an order of magnitude lower than for Code 7740 glass.

Optimization of a fixed solar thermal collector

Criteria are presented for optimizing solar thermal energy collection. These criteria are then used in setting the design of a fixed solar thermal energy collector. This design is obtained by proceeding carefully through a series of optimization steps. While seeking near optimum performance, features have been retained which should lead to low cost. Initial optimization steps lead to an all glass vacuum collector tube whose side and lower walls are internally silvered to provide optimal Winston concentration on an interior glass tube coated with a selective absorber. Heat transfer calculations, performed for an array module of these collector tubes, produce values for the radiation, heat conduction and pumping losses and indicate operating conditions which minimize these losses. Near this minimum, heat conduction and pumping losses are small and can usually be neglected. Liquids provide much better heat transfer than gases. For liquid heat transfer fluids, the minimum loss collector tube window width (setting the transverse scale) is ∼3 cm and tube length ∼4 m, depending somewhat upon array area and the weighting used for the various losses. A window width of∼5 cm and tube length∼2 m should provide lower cost fabrication, while still allowing operation near minimum loss. Skills now used in the glass and lighting industry are expected to lead to low cost production of these tubes.

A Laser Beam-Heated Miniature Oven for Matrix Isolation Raman Studies

High-temperature Knudsen cells of various designs have been used by a number of investigators to measure the matrix-isolation vibrational spectra of inorganic salts. Recently we have initiated a matrix-isolation laser Raman study of inorganic and coordination compounds. This communication reports the design of a novel miniature oven which is heated by a laser beam to vaporize small quantities of solid compounds. The necessity for such a miniature oven arose when we tried to adapt the Cryogenic Technology Inc. model 21 closed cycle helium refrigerator to our Spex model 1430 sample illuminater. Because the latter is also used for ordinary Raman measurements, we planned to minimize its modification so that the matrix-isolation set-up can be converted easily to the normal configuration. The Spex illuminator is equipped with a high aperture Angenieux lens (f/0.95) with a focal length of 25 mm. However, the usable working distance between the lens and the focal plane is only 16 mm. That necessitated the design of a special Pyrex glass vacuum shroud as shown in Fig. 1 (part 1). This shroud is attached to an aluminum sleeve (part 2) which is attached to the refrigerator (part 3). A gas inlet and an electrical feed-through are housed on the aluminum sleeve (not shown in Fig. 1).

Toys III/Avocation: A collector's guide to romance and nostalgia: Where to find antique vacuum tubes, TRF receivers, glass insulators, dc generators, and old trolley cars

Documenting the history of their profession seems to be a popular leisure-time pursuit among electrical and electronics engineers. Collectors and collections abound. Exhibitions range from one at the prestigious Smithsonian, where there are warehouses full of donations still to be unpacked, to small private collections of glass insulators or telegraph keys. The following list serves not only the dedicated historian but the casual sightseer who might be interested in anything from old-time trolleys to antique telephones to memorabilia of some of the profession's best-known pioneers. Exhibit locations are called out in blue so that readers can identify items of interest in their areas, and it should be noted that the list presents only a sampling of the many collectors and groups actively devoted to preserving the romance of engineering's past — and its artifacts.

Physical characteristics of microaggregates in stored blood.

The volume of microaggregates 13 to 80 μ in size which developed in blood components stored under varying conditions was measured with a particle size analyzer. The microaggregates were found to develop progressively during storage of ACD whole blood at 4 to 6 C. Coincident with this there was a drop in the platelet count during the first week of storage and a progressive reduction in the absolute granulocyte count. Microaggregate development after storage of various components of ACD blood was proportional to the concentration of platelets and leukocytes prior to storage. The microaggregates settled into the buffy coat after centrifugation and became larger. In vitro studies indicated that they were resistant to dissociation in vitro in comparison to platelet aggregates induced in fresh blood by adenosine diphosphate. Microaggregate formation was greater in CPD than in ACD anticoagulated blood stored at 4 to 6 C for 24 hours, but was not different after seven days of storage. A greater volume of microaggregates was formed in aliquots of ACD blood stored at 4 to 6 C than at room temperature, while no differences were noted after storage of blood in plastic bags or glass vacuum bottles.