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742. Grids for electronic apparatus
Classified
abstracts
739-747
positioning in units with modulator-diaphragm apertures and modulators of non-planar shape, is described. The method is based on the principle of pneumatic control, using the aperture of the modulator diaphragm as measuring nozzle. In order to eliminate errors of assembly in cathode-modulator distance resulting from a statistical scatter in the diaphragm-aperture dimensions and the shape and thickness of the diaphragm, the required distance is set by means of a template; the pressure in the measuring system corresponding to the correct arrangement of the modulator is noted and then reproduced when the unit is assembled. L V Traube and Yu I Greben’, USSR Patent 184,292, Appl 1I th Feb 1963, Pub1 13th Sept 1966. 33 739. A cathode.
(USSR) A new form of tungsten-base cathode for electronic apparatus is described. Whereas conventional cathodes composed of tungstentantalum or tungsten-niobium alloys give a relatively low electron emission and require the addition of yttrium oxide to supplement this, also proving unstable at high temperatures, the new form of cathode contains higher proportions of tantalum or niobium (up to 20 wt per cent) and is far more heat-resistant, corrosion-resistant, and thermionically stable. The new cathodes have a work function of 3.9 eV and a maximum secondary-emission coefficient of 1.5; they may be used at temperatures in excess of 2OOO’C. A A Gugnin et al, USSR Patent 190,492,Appl25th March 1965, Pub1 31st Jan 1967. 33 740. Method of depositing emission coatings on the cathodes of electrical vacuum systems (electrical apparatus). (USSR) An improved method of depositing emission coatings on the cathodes of electronic apparatus by a plasma-jet method is described. The new method is distinguished by the fact that carbonates of alkaline-earth elements (instead of conventional oxides) are introduced into the plasma jet. This improves the emissive properties of the cathodes and simplifies the technological process of depositing the emitting material. A typical plasma jet is based on an argon atmosphere and has a specific power of 50-100 kW/cm*; on introducing the carbonates as powders these are converted into molten oxides. A deposit of even thickness may be obtained by choosing the correct initial particle size. Access of the emitting substance to non-emitting parts of the cathode is prevented by proper choice of geometry. The results of some initial tests with cathodes of this type are presented and discussed. V V Andreev et al, USSR Patent 190,493, Appl28th June 1965, Pub1 31st Jan 1967.
33 744. A Cathode based on lanthanum hexaboride.
(USSR) Conventional thermionic cathodes based on lanthanum hexaboride as emitting material are described; these have a central cavity filled with the emitter and are heated by radiation or electron bombardment. The new cathode here described differs from the conventional type in that the central cavity is formed by two coaxially-situated cylindrical tubes with openings in their sides. This makes it possible to increase the current taken from the cathode as well as increasing the normal life-time of the latter. A D Runov et al, USSR Patent 192,961, Appl 1st Nov 1965, Pub1 25th April 1967. 33 745. A thermionic cathode.
(USSR) A new thermionic cathode made of a hafnium-scandium alloy capable of giving efficient results at much lower temperatures than the conventional tungsten or tantalum type is described. The new material has a work function of 3.2 eV. giving an emission current density of 4 A/cm2 at 1700°C; the specific resistance at 25°C is 60-90 @cm, the mp is 1900_22OO”C, and the sp gr IO-12 g/cm3. The use of hafnium and scandium, which dissolve considerable quantities of oxygen, means that this cathode may be used in imperfect vacuum conditions. The new cathode is particularly suited for use in apparatus of the magnetron type and other equipment requiring low emission temperatures. I V Burov et al, USSR Patent 193,620, Appl 6th April 1966, Pub1 13th March
1967.
34. HIGH ALTITUDE AND SPACE TECHNOLOGY 33
741. An oxide cathode.
(USSR) A new form of oxide cathode for electronic apparatus is proposed. This cathode is distinguished by the fact that aluminium is used as anti-emission substance preventing the thermionic emission of the oxide on the non-working surface instead of the conventional iridium or osmium. Aluminium is more easily melted and deposited on the cathode surface than the other elements and also enables the unwanted emission to be more effectively suppressed. The properties of cathodes carrying a surface film of aluminium were studied in ordinary diodes and also by a field-emission technique. The film reduced the emission of the oxide by over 600 times at 7Oo”C, without harming that of adjacent working parts of the cathode or losing its effectiveness with time. A N Kim et al, USSR Patent 190,494, Appl6th Jan 1966, Pub1 31st Jan 1967. 33 742. Grids for electronic apparatus.
33 743. An electrode for high power pulsed electronic vacuum apparatus. (USSR) The dilliculties arising in conventional high-power pulsed electronic devices when copper electrodes subjected to strong pulses of electron currents melt under the impact of the latter are described, together with some of the existing methods of mitigating this danger. A feature of the new form of electrode here proposed is the fact that a film of tungsten or other refractory metal is deposited on the copper surface to prevent the latter from melting. This makes it possible to raise the pulse power by a factor of several times as compared with the unguarded copper electrode. Some preferred methods of producing the surface film of refractory metal are described. V F Maksimov, USSR Patent 192, 963, Appl9th March 1962, Pub1 2nd March 1967.
(USSR) A new and improved construction for the grids of electronic apparatus is described. In the conventional construction based on a system of longitudinal and transverse cross-pieces forming rectangular cells, the grid as a whole tends to sag as the apparatus ages. In the new form of construction the longitudinal cross-pieces are displaced relative to one another through half a step in two mutually perpendicular directions. This greatly reduces the sag in the grid as a whole when the system of which it forms a part is heated to high temperatures. I I Sazhin, USSR Patent 190,496, Appl21st Aug 1965, Pub1 21st Feb 1967.
34 : 18 Fundamental plasma processes in electron-bombardment-thruster ionization chambers. See abstract number 645. 34 : 21 Research and development programme for rocket-borne cryosorption pump. See abstract number 665. 34 : 17 Cryogenic research at the Los Alamos scientific laboratory. See abstract number 714. Surface interaction between aluminium single crystals at lo-“’ torr. See abstract number 756. 34 746. Design concepts for a combined space environmental effects test facility. (Great Britain) A combined space environmental effects facility was designed, built and used to evaluate synergistic effects on optical properties of materials used on the external surfaces of spacecraft. Of primary concern was the in situ measurement of spectral optical changes for commonly used thermal control materials. To accomplish this, an ultrahigh vacuum chamber is used together with irradiation sources for near and vacuum ultraviolet, low energy protons, electrons, and X-ray simulation. In situ reflectance measurements were performed to determine solar absorptivity changes. S J Babjak et al, Vucuum ,lS (2), Feb 1968, 57-63. 34 : 20 747. Space applications of cryogenic technology. (USA) Three areas of cryogenic technology pertinent to space applications are discussed: tank design for long term storage; miniaturized 303
abstracts
739-747
positioning in units with modulator-diaphragm apertures and modulators of non-planar shape, is described. The method is based on the principle of pneumatic control, using the aperture of the modulator diaphragm as measuring nozzle. In order to eliminate errors of assembly in cathode-modulator distance resulting from a statistical scatter in the diaphragm-aperture dimensions and the shape and thickness of the diaphragm, the required distance is set by means of a template; the pressure in the measuring system corresponding to the correct arrangement of the modulator is noted and then reproduced when the unit is assembled. L V Traube and Yu I Greben’, USSR Patent 184,292, Appl 1I th Feb 1963, Pub1 13th Sept 1966. 33 739. A cathode.
(USSR) A new form of tungsten-base cathode for electronic apparatus is described. Whereas conventional cathodes composed of tungstentantalum or tungsten-niobium alloys give a relatively low electron emission and require the addition of yttrium oxide to supplement this, also proving unstable at high temperatures, the new form of cathode contains higher proportions of tantalum or niobium (up to 20 wt per cent) and is far more heat-resistant, corrosion-resistant, and thermionically stable. The new cathodes have a work function of 3.9 eV and a maximum secondary-emission coefficient of 1.5; they may be used at temperatures in excess of 2OOO’C. A A Gugnin et al, USSR Patent 190,492,Appl25th March 1965, Pub1 31st Jan 1967. 33 740. Method of depositing emission coatings on the cathodes of electrical vacuum systems (electrical apparatus). (USSR) An improved method of depositing emission coatings on the cathodes of electronic apparatus by a plasma-jet method is described. The new method is distinguished by the fact that carbonates of alkaline-earth elements (instead of conventional oxides) are introduced into the plasma jet. This improves the emissive properties of the cathodes and simplifies the technological process of depositing the emitting material. A typical plasma jet is based on an argon atmosphere and has a specific power of 50-100 kW/cm*; on introducing the carbonates as powders these are converted into molten oxides. A deposit of even thickness may be obtained by choosing the correct initial particle size. Access of the emitting substance to non-emitting parts of the cathode is prevented by proper choice of geometry. The results of some initial tests with cathodes of this type are presented and discussed. V V Andreev et al, USSR Patent 190,493, Appl28th June 1965, Pub1 31st Jan 1967.
33 744. A Cathode based on lanthanum hexaboride.
(USSR) Conventional thermionic cathodes based on lanthanum hexaboride as emitting material are described; these have a central cavity filled with the emitter and are heated by radiation or electron bombardment. The new cathode here described differs from the conventional type in that the central cavity is formed by two coaxially-situated cylindrical tubes with openings in their sides. This makes it possible to increase the current taken from the cathode as well as increasing the normal life-time of the latter. A D Runov et al, USSR Patent 192,961, Appl 1st Nov 1965, Pub1 25th April 1967. 33 745. A thermionic cathode.
(USSR) A new thermionic cathode made of a hafnium-scandium alloy capable of giving efficient results at much lower temperatures than the conventional tungsten or tantalum type is described. The new material has a work function of 3.2 eV. giving an emission current density of 4 A/cm2 at 1700°C; the specific resistance at 25°C is 60-90 @cm, the mp is 1900_22OO”C, and the sp gr IO-12 g/cm3. The use of hafnium and scandium, which dissolve considerable quantities of oxygen, means that this cathode may be used in imperfect vacuum conditions. The new cathode is particularly suited for use in apparatus of the magnetron type and other equipment requiring low emission temperatures. I V Burov et al, USSR Patent 193,620, Appl 6th April 1966, Pub1 13th March
1967.
34. HIGH ALTITUDE AND SPACE TECHNOLOGY 33
741. An oxide cathode.
(USSR) A new form of oxide cathode for electronic apparatus is proposed. This cathode is distinguished by the fact that aluminium is used as anti-emission substance preventing the thermionic emission of the oxide on the non-working surface instead of the conventional iridium or osmium. Aluminium is more easily melted and deposited on the cathode surface than the other elements and also enables the unwanted emission to be more effectively suppressed. The properties of cathodes carrying a surface film of aluminium were studied in ordinary diodes and also by a field-emission technique. The film reduced the emission of the oxide by over 600 times at 7Oo”C, without harming that of adjacent working parts of the cathode or losing its effectiveness with time. A N Kim et al, USSR Patent 190,494, Appl6th Jan 1966, Pub1 31st Jan 1967. 33 742. Grids for electronic apparatus.
33 743. An electrode for high power pulsed electronic vacuum apparatus. (USSR) The dilliculties arising in conventional high-power pulsed electronic devices when copper electrodes subjected to strong pulses of electron currents melt under the impact of the latter are described, together with some of the existing methods of mitigating this danger. A feature of the new form of electrode here proposed is the fact that a film of tungsten or other refractory metal is deposited on the copper surface to prevent the latter from melting. This makes it possible to raise the pulse power by a factor of several times as compared with the unguarded copper electrode. Some preferred methods of producing the surface film of refractory metal are described. V F Maksimov, USSR Patent 192, 963, Appl9th March 1962, Pub1 2nd March 1967.
(USSR) A new and improved construction for the grids of electronic apparatus is described. In the conventional construction based on a system of longitudinal and transverse cross-pieces forming rectangular cells, the grid as a whole tends to sag as the apparatus ages. In the new form of construction the longitudinal cross-pieces are displaced relative to one another through half a step in two mutually perpendicular directions. This greatly reduces the sag in the grid as a whole when the system of which it forms a part is heated to high temperatures. I I Sazhin, USSR Patent 190,496, Appl21st Aug 1965, Pub1 21st Feb 1967.
34 : 18 Fundamental plasma processes in electron-bombardment-thruster ionization chambers. See abstract number 645. 34 : 21 Research and development programme for rocket-borne cryosorption pump. See abstract number 665. 34 : 17 Cryogenic research at the Los Alamos scientific laboratory. See abstract number 714. Surface interaction between aluminium single crystals at lo-“’ torr. See abstract number 756. 34 746. Design concepts for a combined space environmental effects test facility. (Great Britain) A combined space environmental effects facility was designed, built and used to evaluate synergistic effects on optical properties of materials used on the external surfaces of spacecraft. Of primary concern was the in situ measurement of spectral optical changes for commonly used thermal control materials. To accomplish this, an ultrahigh vacuum chamber is used together with irradiation sources for near and vacuum ultraviolet, low energy protons, electrons, and X-ray simulation. In situ reflectance measurements were performed to determine solar absorptivity changes. S J Babjak et al, Vucuum ,lS (2), Feb 1968, 57-63. 34 : 20 747. Space applications of cryogenic technology. (USA) Three areas of cryogenic technology pertinent to space applications are discussed: tank design for long term storage; miniaturized 303