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836. Mass spectrometer ion source
Classified
abstracts MCI-843
photon pressure in radiometer effect gauges, has been extended by the utilization of specular reflection from the gauge surfaces. A R Beavitt et al, J Sci Instrum (J Phys E), Ser 2, 1 (l), 1968, 45-51. 22 830. An improved method of sealing the compression capillary of a McLeod gauge. (Great Britain) Important advantages were achieved when the end of the compression capillary of a McLeod gauge was sealed by cementing on a flat glass (Australia) disk instead of by fusion of the end of the capillary. G R Reid, J Sci Instrum, (J Phys I?), Ser 2, 1 (1). 1968, 6&61. 22 831. Correction to teat header arrangement for determining the speed of pumps using an orifice type impact pressure transducer. (Great Britain) In an earlier paper by the authors (J Sci Instrum 43, 1966, 893-898), molecular wall flux for a cylindrical test dome was assumed to be linear. It is shown that if deviations from linearity are taken into account a correction can be applied to the recommended gauge position for test domes with a ratio of length to radius larger than 4. W Steckehnacher and D J Turner, J Sci Instrum, (J Phys E), Ser 2, 1 (l), 1968, 70-71. 22 832. Extension of gauge calibration study in extreme high vacuum. (USA) Continuing efforts to develop more reliable and higher sensitivity pressure gauges for pressures below lo-lo torr are reported. Consideration is given to the orbitron gauge, which has a high potential for measuring extremely low pressures and also for performing aerospace pressure measurements. A method was developed for obtaining a self-consistent solution for the electron motion, charge density distribution and space charge and space charge dependent potential distribution in an orbitron. A normal magnetron gauge is also described. Major emphasis was on the measurement of the sensitivities of a magnetron gauge over wide ranges of anode voltages, magnetron field strength, and pressures. A study was made on the rf oscillatory behaviour of the normal magnetron gauge. The generation of stable rf frequencies could not be detected below 2 x lo-lo torrthe pressure below which the gauge is nonlinear. F Feakes et al, Rep NASA-CR-904, Ott 1967, 153 pages (Sci Tech Aerospace Reps, 5 (24), 4454, N67-40398). 22 :21 833. A small volume, ultrahigh vacuum system for ionization gauge studies. (USA) A small ultrahigh vacuum system operating at estimated pressures of less than 5 x lo-la torr is described. These pressures are obtained by a combination of gauge and cryogenic pumping and a rigorous baking procedure. The system was specifically designed for study of magnetron ionization gauge characteristics, but can be used additionally to study any low outgassing device small enough to fit the system. Details of the system and of the techniques used for obtaining the low pressure are presented. A discussion of the pressure measurement techniques is given and calculations are shown which estimate the ultimate pressure obtained by the system. R A Outlaw and J M Bradford. Reo NASA-TN-D-4208. Nov 1967.20 ’ pages (Sci Tech Aerospace Reps, 5(24), 4455, N67-40566). 22 834. Spherical chamber for calibrating vacuum gauges. (USA) A vacuum calibrator for internally calibrating vacuum gauges is spherically shaped to facilitate uniform gas molecular distribution. Also, further molecular distribution is achieved by means of an additional distributing device prior to entry of the molecules of gas. McDonnell Douglas Coru. US Patent 3.367.169. Official Gaz. US ’ ’ *I Patent Ofice, 847 (l), 6th Fe6 1968, 64. ’ 22 835. Mass spectrometer. (Germany) Of the omegatron type with circular periodic ion acceleration, the spectrometer has a high-frequency electrical field perpendicular to the electron beam producing the ions and a dc magnetic field parallel to the electron beam. An additional hf electrical field is applied eeroendicular to the other two fields, whereby the additional field is in quadrature with the first electrical field and its frequency is at the most a whole multiple of that of the first field. Leybold-Heraeus GmbH & Co KG, German Patent 1,258,148, Patent Abstr, 8 (6) part D, 14th Feb 1968, 7.
22 836. Mass spectrometer ion source. (Great Britain) Usable down to very low pressures, the source consists of an emitter and magnet assembly. The assembly includes a pair of spaced apertured end plates, a hollow cylindrical magnet disposed between the end plates and an electron emitter mounted to protrude through the aperture in one end plate into the magnet. An ion source circuit maintains the end plates at a potential negative with respect to the emitter and the magnet positive relative to the emitter. General Electric Co, British Patent 1.101,288, Patent Abstr, 8 (8) part D, 16th Feb 1968, 5. 23. PLUMBING 23 : 33 Helium vapour cooled current leads. See abstract number 889. 23 837. Gold wke seals for ultrahigh vacuum. (USA) Advantages of gold as sealing material in ultrahigh vacuum are discussed. A new configuration of unpolarized rotatable UHV flanges, sealed with a gold wire gasket, is described. Use of gold wire for sealing irregularly shaped openings, glass windows, and thin foils in vacuum systems is also discussed. R A Hawrylak, J Vat Sci Technoi, 4 (6), Nov/Dec 1967.364-367. 23 838. Infrared windows for ultrahigh vacuum use. (USA) Irtran (Kodak) windows were sealed by using low vapour pressure silicone resin (Vacseal). Pressures of the order of 5 x lo--” torr were attained. The techniques used for applying and curing the resin are described. L J Schkolnick, Rev Sci Instrum. 39 (l), 1968, 122-123. 23 : 43 839. Thin 6lm windows for liquid hydrogen containment. (Holland) Several methods are described for the containment of cryogenic liquids behind demountable thin (0.005 cm) plastic windows. Tests were made using liquid hydrogen. Properties of Kapton films are discussed and sealing methods for the windows are described. (Great Britain) P M Martin and E Wood, Nucl Instrum Methods, 59 (1). 1968,61-63. 23 840. High-speed rotating vacuum seal. (Holland) A high-speed rotating vacuum seal is described which has a relatively long life and a low leak rate, is oil free and easy to maintain. The seal is based on a Rulon A (loaded Teflon) ring running against a mild steel insert, and using a guard vacuum. The seal has a 2.5-inch diameter opening and operates at 1100 rpm. Typical seal life was 1000 hours between replacement of sealing parts. (USA) R Booth, Nucl Instrum Methods, 59 (l), 1968, 131-135. 23 841. Metal-to-ceramic seal. (USA) In a novel seal between a ceramic body and a metal flange, the flange is fitted into a recess between two ceramic elements and the recess filled with a fused glass sealant to bond the ceramic bodies and the metal flange in gastight relationship. Engelbard Industries, US Patent 3,367,696, Official Gaz US Patent Ofice, 847 (l), 6th Feb 1968, 201. 23 842. Hermetically sealed envelope structure for vacuum componeut. (USA) An envelope structure is provided utilising a flexible metallic seal interposed between metallic and dielectric portions of the envelope in such a way as to accommodate differences in thermal expansion and contraction between the metal and dielectric and so preserve the integrity of the hermetic seal. The seal is formed so that no part of the end cap structure or seal flange extends beyond the outer periphery of the dielectric part. Jennings Radio Mfg Corp, US Patent 3,368,023, Official Gaz US Patent Ofice, 847 (1) 6th Feb 1968, 266. 23 843. Vacuum vessel fitting. (Great Britain) A rod, such as an electrical lead-in conductor or a rotary shaft, extends through a hole in the vessel wall and is mounted in an elastomeric sleeve or bush which can be compressed endwise and thus radially expanded between its ends (eg to seal the hole) while the ends are confined by respective rings or tubes. Bl-Vat Ltd, British Patent l&X9,548, Patent Abstr, 8 (6) part B, 9th Feb 1968, 3. 357
abstracts MCI-843
photon pressure in radiometer effect gauges, has been extended by the utilization of specular reflection from the gauge surfaces. A R Beavitt et al, J Sci Instrum (J Phys E), Ser 2, 1 (l), 1968, 45-51. 22 830. An improved method of sealing the compression capillary of a McLeod gauge. (Great Britain) Important advantages were achieved when the end of the compression capillary of a McLeod gauge was sealed by cementing on a flat glass (Australia) disk instead of by fusion of the end of the capillary. G R Reid, J Sci Instrum, (J Phys I?), Ser 2, 1 (1). 1968, 6&61. 22 831. Correction to teat header arrangement for determining the speed of pumps using an orifice type impact pressure transducer. (Great Britain) In an earlier paper by the authors (J Sci Instrum 43, 1966, 893-898), molecular wall flux for a cylindrical test dome was assumed to be linear. It is shown that if deviations from linearity are taken into account a correction can be applied to the recommended gauge position for test domes with a ratio of length to radius larger than 4. W Steckehnacher and D J Turner, J Sci Instrum, (J Phys E), Ser 2, 1 (l), 1968, 70-71. 22 832. Extension of gauge calibration study in extreme high vacuum. (USA) Continuing efforts to develop more reliable and higher sensitivity pressure gauges for pressures below lo-lo torr are reported. Consideration is given to the orbitron gauge, which has a high potential for measuring extremely low pressures and also for performing aerospace pressure measurements. A method was developed for obtaining a self-consistent solution for the electron motion, charge density distribution and space charge and space charge dependent potential distribution in an orbitron. A normal magnetron gauge is also described. Major emphasis was on the measurement of the sensitivities of a magnetron gauge over wide ranges of anode voltages, magnetron field strength, and pressures. A study was made on the rf oscillatory behaviour of the normal magnetron gauge. The generation of stable rf frequencies could not be detected below 2 x lo-lo torrthe pressure below which the gauge is nonlinear. F Feakes et al, Rep NASA-CR-904, Ott 1967, 153 pages (Sci Tech Aerospace Reps, 5 (24), 4454, N67-40398). 22 :21 833. A small volume, ultrahigh vacuum system for ionization gauge studies. (USA) A small ultrahigh vacuum system operating at estimated pressures of less than 5 x lo-la torr is described. These pressures are obtained by a combination of gauge and cryogenic pumping and a rigorous baking procedure. The system was specifically designed for study of magnetron ionization gauge characteristics, but can be used additionally to study any low outgassing device small enough to fit the system. Details of the system and of the techniques used for obtaining the low pressure are presented. A discussion of the pressure measurement techniques is given and calculations are shown which estimate the ultimate pressure obtained by the system. R A Outlaw and J M Bradford. Reo NASA-TN-D-4208. Nov 1967.20 ’ pages (Sci Tech Aerospace Reps, 5(24), 4455, N67-40566). 22 834. Spherical chamber for calibrating vacuum gauges. (USA) A vacuum calibrator for internally calibrating vacuum gauges is spherically shaped to facilitate uniform gas molecular distribution. Also, further molecular distribution is achieved by means of an additional distributing device prior to entry of the molecules of gas. McDonnell Douglas Coru. US Patent 3.367.169. Official Gaz. US ’ ’ *I Patent Ofice, 847 (l), 6th Fe6 1968, 64. ’ 22 835. Mass spectrometer. (Germany) Of the omegatron type with circular periodic ion acceleration, the spectrometer has a high-frequency electrical field perpendicular to the electron beam producing the ions and a dc magnetic field parallel to the electron beam. An additional hf electrical field is applied eeroendicular to the other two fields, whereby the additional field is in quadrature with the first electrical field and its frequency is at the most a whole multiple of that of the first field. Leybold-Heraeus GmbH & Co KG, German Patent 1,258,148, Patent Abstr, 8 (6) part D, 14th Feb 1968, 7.
22 836. Mass spectrometer ion source. (Great Britain) Usable down to very low pressures, the source consists of an emitter and magnet assembly. The assembly includes a pair of spaced apertured end plates, a hollow cylindrical magnet disposed between the end plates and an electron emitter mounted to protrude through the aperture in one end plate into the magnet. An ion source circuit maintains the end plates at a potential negative with respect to the emitter and the magnet positive relative to the emitter. General Electric Co, British Patent 1.101,288, Patent Abstr, 8 (8) part D, 16th Feb 1968, 5. 23. PLUMBING 23 : 33 Helium vapour cooled current leads. See abstract number 889. 23 837. Gold wke seals for ultrahigh vacuum. (USA) Advantages of gold as sealing material in ultrahigh vacuum are discussed. A new configuration of unpolarized rotatable UHV flanges, sealed with a gold wire gasket, is described. Use of gold wire for sealing irregularly shaped openings, glass windows, and thin foils in vacuum systems is also discussed. R A Hawrylak, J Vat Sci Technoi, 4 (6), Nov/Dec 1967.364-367. 23 838. Infrared windows for ultrahigh vacuum use. (USA) Irtran (Kodak) windows were sealed by using low vapour pressure silicone resin (Vacseal). Pressures of the order of 5 x lo--” torr were attained. The techniques used for applying and curing the resin are described. L J Schkolnick, Rev Sci Instrum. 39 (l), 1968, 122-123. 23 : 43 839. Thin 6lm windows for liquid hydrogen containment. (Holland) Several methods are described for the containment of cryogenic liquids behind demountable thin (0.005 cm) plastic windows. Tests were made using liquid hydrogen. Properties of Kapton films are discussed and sealing methods for the windows are described. (Great Britain) P M Martin and E Wood, Nucl Instrum Methods, 59 (1). 1968,61-63. 23 840. High-speed rotating vacuum seal. (Holland) A high-speed rotating vacuum seal is described which has a relatively long life and a low leak rate, is oil free and easy to maintain. The seal is based on a Rulon A (loaded Teflon) ring running against a mild steel insert, and using a guard vacuum. The seal has a 2.5-inch diameter opening and operates at 1100 rpm. Typical seal life was 1000 hours between replacement of sealing parts. (USA) R Booth, Nucl Instrum Methods, 59 (l), 1968, 131-135. 23 841. Metal-to-ceramic seal. (USA) In a novel seal between a ceramic body and a metal flange, the flange is fitted into a recess between two ceramic elements and the recess filled with a fused glass sealant to bond the ceramic bodies and the metal flange in gastight relationship. Engelbard Industries, US Patent 3,367,696, Official Gaz US Patent Ofice, 847 (l), 6th Feb 1968, 201. 23 842. Hermetically sealed envelope structure for vacuum componeut. (USA) An envelope structure is provided utilising a flexible metallic seal interposed between metallic and dielectric portions of the envelope in such a way as to accommodate differences in thermal expansion and contraction between the metal and dielectric and so preserve the integrity of the hermetic seal. The seal is formed so that no part of the end cap structure or seal flange extends beyond the outer periphery of the dielectric part. Jennings Radio Mfg Corp, US Patent 3,368,023, Official Gaz US Patent Ofice, 847 (1) 6th Feb 1968, 266. 23 843. Vacuum vessel fitting. (Great Britain) A rod, such as an electrical lead-in conductor or a rotary shaft, extends through a hole in the vessel wall and is mounted in an elastomeric sleeve or bush which can be compressed endwise and thus radially expanded between its ends (eg to seal the hole) while the ends are confined by respective rings or tubes. Bl-Vat Ltd, British Patent l&X9,548, Patent Abstr, 8 (6) part B, 9th Feb 1968, 3. 357