- Email: [email protected]
653. Pneumatic gauges for in-pile measurements
Classified Abstracts 648---660 is generated at the required frequency by a phase-shift oscillator, and fed to a modulator valve whose gain is controlled by the d.c. emission current of the gauge. A push-pull power amplifier and a 30-W step-down transformer supply the gauge filament. The resulting positive ion current varied during a pulse of magnetic field, and pressure readings have to be taken while the field is off. A stability of 1 per cent over the pressure range 10-3-10 -6 torr is claimed. M.D.A. G. A. Doran, J. Sci. lnstrum., 38 (9), Sept. 1961, 355-356. 22 648. Emission control for the omegatron-type mass spectrometer. United States. This note describes a modification of the ionization gauge control circuit of Steckelmacher and Van der Meer (J. Sci. Instrum., 27, 1950, 189), to allow its use with an omegatron. The control unit monitors the target current of the omegatron and regulates the filament heating current so as to maintain the target current within ± 3 per cent. The consequent improvement in performance is quoted as a reduction in the long-term zero drift of the electrometer from ~=40 per cent (with a 101° ohm input resistor) to ± 5 per cent (with the same input resistor), or ± 10 per cent (with a resistor 10 times greater).
327 22
653. Pneumatic gauges for in-pile measurements. J. Pefhany, Nucl. Engng, 6 (57), Feb. 1961, 77-79. 22 654. A new system to calibrate 10 -9 torr. Anon., R & D, (13), Sept. 1962, 64. 22 655. New wide-range pressure transducer. United States. A new transducer has been developed that will measure pressure over a wide range by sensing the damping of a vibrating diaphragm immersed in the gas whose pressure is being measured. It is capable of measuring pressures from approx. 10 -5 to 200 m m Hg with an accuracy of about 1 per cent over a large portion of the range. The device overcomes many of the shortcomings characteristic of other gauges ; it is small and rugged with a fast response time at low pressures, and lends itself well to automatic operation. (Authors) J. Dimeff, J. W. Lane and G. W. Coon, Rev. Sci. Instrum., 33 (8), Aug. 1962, 804-811. 23.
M . D . A.
G. R. Giedd and G. C. Roberts, J. Sci. Instrum., 38 (9), Sept. 1961, 361-362. 22 649. N.E.L. vacuum manometer. Anon., J. Sci. Instrum., 38 (9), Sept. 1961, 382. 22 650. Mass spectrometers. Anon., J. Sci. Instrum., 38 (9), Sept. 1961, 383. 22 651. Simple electromanometer utilizing the cadmium sulphide photoconductive cell. Japan. This short paper describes a method of converting the liquid level in a mercury or water manometer into an electrical signal for ease of recording. Photoconductive cells constructed in the form of narrow strips are used ; one of these can be placed in the shadow cast by the mercury column when it is strongly illuminated by a small projection lamp. If the column falls, a greater length of the cell is exposed to the light, and vice versa, with a corresponding variation in cell resistance. The CdS cell was chosen for low dark current, high maximum power output (up to one watt), and high sensitivity compared to other cells. By proper choice of liquid, and of cell length, it is possible to operate with pressures from a few mm of water to several hundred mm of mercury, and over a dynamic range of 1 to 300 mm. Applications of the instrument in biological studies are mentioned. M.D.A. T. Azuma, T. K a n n o and T. Hirota, J. Sci. lnstrum., 38 (10), Oct. 1961, 413-414. 22:51 652. Experimental microbarograph. Great Britain. This note describes an experimental microbarograph which was used to record small variations in atmospheric pressure in connexion with work on radio wave propagation in the troposphere. The unit consists of an aneroid cell carrying a metal plate which forms one plate of a small airspaced capacitor. The capacitance changes are detected by making the unit form part of the capacitance of an L - C circuit, which is fed from a crystal oscillator. The circuit is tuned slightly off resonance, so that changes in capacitance cause changes in the circulating current ; a sample of this current is rectified and used to operate a recorder. The range of measurement is 3 rob, with a sensitivity of about 0.I rob. M.D.A. G. W. Gardiner, J. Sci. Instrum., 38 (12), Dec. 1961, 510-511.
Plumbing 23
656. Flexible couplings for tubes under vacuum. Anon., Engineer, 213 (5540), 30 March 1962, 586. 23 657. Strain relief and separation in rigid metal/glass vacuum systems. Great Britain. This note suggests the introduction of a loop (similar to a U-tube) in the glass-ware between two fixed parts of the system, to reduce the risk of breakage due to expansion if the whole system is heated ; the loop has sufficient resilience to absorb the strain. By simultaneously heating a constriction in either limb, and pulling the loop in a direction perpendicular to the main run of the tubing which joins the fixed sections, these can be sealed off without the need to separate them in the usual way. M.D.A. T. G. Cork, J. Sci. Instrum., 38 (8), Aug. 1961, 338. 23 658. Aluminium bakeable vacuum seal. Great Britain. This note describes attempts to extend the use of aluminium wire gaskets described previously (e.g., Elsworth et al., J. Sci. Instrum., 37, 1960, 449) to 15-in. diameter flanges. Some failures were experienced due to the aluminium flowing and so allowing the bolts to slacken effectively, before the gaskets had adhered to the flanges. Satisfactory results are reported with the addition of either " Belville ", or conical spring washers under the heads of the clamping bolts to ensure that the joint is compressed throughout the baking operation. M . D . A.
L. Holland, J. Sci. Instram., 38 (8), Aug. 1961, 339. 23 659. Simple technique for strong solderable thin film contacts suitable to 4.2°K. P. R. Gould and J. J. Finnegan, Rev. Sci. Instrum., 33 (7), July 1962, 767-769. 23 660. Bakeable indium seals. S. Pakswer and J. Dowd, Rev. Sci. Instrum., 33 (7), July 1962, 780--781. 23:42 Seal between silica tubing and glass apparatus. See Abstr. No. 754.
327 22
653. Pneumatic gauges for in-pile measurements. J. Pefhany, Nucl. Engng, 6 (57), Feb. 1961, 77-79. 22 654. A new system to calibrate 10 -9 torr. Anon., R & D, (13), Sept. 1962, 64. 22 655. New wide-range pressure transducer. United States. A new transducer has been developed that will measure pressure over a wide range by sensing the damping of a vibrating diaphragm immersed in the gas whose pressure is being measured. It is capable of measuring pressures from approx. 10 -5 to 200 m m Hg with an accuracy of about 1 per cent over a large portion of the range. The device overcomes many of the shortcomings characteristic of other gauges ; it is small and rugged with a fast response time at low pressures, and lends itself well to automatic operation. (Authors) J. Dimeff, J. W. Lane and G. W. Coon, Rev. Sci. Instrum., 33 (8), Aug. 1962, 804-811. 23.
M . D . A.
G. R. Giedd and G. C. Roberts, J. Sci. Instrum., 38 (9), Sept. 1961, 361-362. 22 649. N.E.L. vacuum manometer. Anon., J. Sci. Instrum., 38 (9), Sept. 1961, 382. 22 650. Mass spectrometers. Anon., J. Sci. Instrum., 38 (9), Sept. 1961, 383. 22 651. Simple electromanometer utilizing the cadmium sulphide photoconductive cell. Japan. This short paper describes a method of converting the liquid level in a mercury or water manometer into an electrical signal for ease of recording. Photoconductive cells constructed in the form of narrow strips are used ; one of these can be placed in the shadow cast by the mercury column when it is strongly illuminated by a small projection lamp. If the column falls, a greater length of the cell is exposed to the light, and vice versa, with a corresponding variation in cell resistance. The CdS cell was chosen for low dark current, high maximum power output (up to one watt), and high sensitivity compared to other cells. By proper choice of liquid, and of cell length, it is possible to operate with pressures from a few mm of water to several hundred mm of mercury, and over a dynamic range of 1 to 300 mm. Applications of the instrument in biological studies are mentioned. M.D.A. T. Azuma, T. K a n n o and T. Hirota, J. Sci. lnstrum., 38 (10), Oct. 1961, 413-414. 22:51 652. Experimental microbarograph. Great Britain. This note describes an experimental microbarograph which was used to record small variations in atmospheric pressure in connexion with work on radio wave propagation in the troposphere. The unit consists of an aneroid cell carrying a metal plate which forms one plate of a small airspaced capacitor. The capacitance changes are detected by making the unit form part of the capacitance of an L - C circuit, which is fed from a crystal oscillator. The circuit is tuned slightly off resonance, so that changes in capacitance cause changes in the circulating current ; a sample of this current is rectified and used to operate a recorder. The range of measurement is 3 rob, with a sensitivity of about 0.I rob. M.D.A. G. W. Gardiner, J. Sci. Instrum., 38 (12), Dec. 1961, 510-511.
Plumbing 23
656. Flexible couplings for tubes under vacuum. Anon., Engineer, 213 (5540), 30 March 1962, 586. 23 657. Strain relief and separation in rigid metal/glass vacuum systems. Great Britain. This note suggests the introduction of a loop (similar to a U-tube) in the glass-ware between two fixed parts of the system, to reduce the risk of breakage due to expansion if the whole system is heated ; the loop has sufficient resilience to absorb the strain. By simultaneously heating a constriction in either limb, and pulling the loop in a direction perpendicular to the main run of the tubing which joins the fixed sections, these can be sealed off without the need to separate them in the usual way. M.D.A. T. G. Cork, J. Sci. Instrum., 38 (8), Aug. 1961, 338. 23 658. Aluminium bakeable vacuum seal. Great Britain. This note describes attempts to extend the use of aluminium wire gaskets described previously (e.g., Elsworth et al., J. Sci. Instrum., 37, 1960, 449) to 15-in. diameter flanges. Some failures were experienced due to the aluminium flowing and so allowing the bolts to slacken effectively, before the gaskets had adhered to the flanges. Satisfactory results are reported with the addition of either " Belville ", or conical spring washers under the heads of the clamping bolts to ensure that the joint is compressed throughout the baking operation. M . D . A.
L. Holland, J. Sci. Instram., 38 (8), Aug. 1961, 339. 23 659. Simple technique for strong solderable thin film contacts suitable to 4.2°K. P. R. Gould and J. J. Finnegan, Rev. Sci. Instrum., 33 (7), July 1962, 767-769. 23 660. Bakeable indium seals. S. Pakswer and J. Dowd, Rev. Sci. Instrum., 33 (7), July 1962, 780--781. 23:42 Seal between silica tubing and glass apparatus. See Abstr. No. 754.