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753. Cathode for devices of the UHF magnetron type
Classified
abstracts
747-758
30 747. Photographic registration of field injected electrons. (Germany) Direct evidence is presented for the photographic action of held injected electrons into an evaporated layer of silver bromide, with thickness of 0.5 pm, from semiconductor gallium arsenide substrate. (Bulgaria) V Zhelev et al, Whys Srat Sol (a), 10 (I), March 1972, K5-K7. 30 748. Influence of pressure on the electronic conduction in tetrahedrally bonded amorphous semiconductors. (Germany) The influence of uniaxial elastic deformation on the conduction in thin films of tetrahedrally bonded amorphous semiconductors Ge, Si and 111-V compounds is investigated as a function of temperature for stress parallel and perpendicular to the current direction. The amorphous films were prepared by evaporation on cooled substrates in a vacuum of about IO-” torr. W Fuchs, Phys Stat Sol (a), 10 (I ), March 1972, 201-207. 30 749. Semiconductivity in chromium (111) trisacetylacetone. (Germany) Thin films of a chromium (Ill) trisacetylacetone complex evaporated in vacuum on collodion or gold are found to be p-type wide-band semiconductors. Current-voltage characteristics in the dark and under illumination are measured. (France) A P Chappe and J I Vargas, Phys Sfut So/ (a), 10 (2), April 1972, 543-554. 30 750. Germanium films on sapphire and germanium substrates. (Germany) Germanium films were prepared by electron beam evaporation of intrinsic germanium at residual gas pressure less than IO-’ torr with the deposition rate of IO3 Ajmin on substrates kept at temperatures ranging from 700 to 8OO’C. The germanium films deposited simultaneously on sapphire and single crystal germanium substrates appear to have the same electrical transport properties. These results are in contrast to the observed crystalline structure, which show coherent crystalline film growth on germanium crystals while films on sapphire are polycrystalline with random crystallite orientation. Conduction in germanium films on germanium substrates is satisfactorily described by a composite conduction model in which the film is separated from the substrate by an interface barrier layer. (Norway) J S Johannessen, Whys Stat So/ (a), 10 (2), April 1972, 569-580. 30 751. Negative resistance in organic monomolecular layers sandwiched between metal electrodes, (Germany) Monomolecular layers of cadmium arachide were employed as insulator in sandwich structures Al stripe-insulator-evaporated Au or Al electrode. It is shown that organic films can exhibit lowfrequency differential negative resistance if they are placed in vacuum of 10e3 torr. K H Gundlach and J Kadlec, R1.y.~ Stut Sol (a), 10 (2), April 1972, 371-379. 30 752. Kinetics of phase transformation amorphous stateepolycrystal in films of semiconductors. (USSR) Kinetics of phase transformation amorphous state polycrystal in amorphous film of GeFe with thickness of IO-’ cm, prepared by thermal evaporation in vacuum, is investigated. The films were heated by a powerful light pulse with a rate of IO” grad/s. Phase transition was observed by measurement of electrical conductivity using the ultrahigh frequency contact-less method. V 1 Zaliva and V P Zakharov, Pisfna ZhETF, 15 (I ), 1972, 21-24 (in Russian). 31. EVACUATION
AND
SEALING
31 753. Cathode for devices of the UHF magnetron type. (USSR) An improved cathode construction for use in UHF magnetrons is described. Field-emitters are provided in the form of rows of sharp points or edges placed in regions subject to only slight electron bombardment. The steady electric field created by the anode has an axial component parallel to the external magnetic field. Under the action of this electric field the electrons emitted from the field emitters are accelerated and pass into the interaction space. Some return to the cathode and eject secondary electrons. For a radius of curvature of the sharp points equal to 1 pm and a voltage of 20 kV, an emission 384
current of 20 mA may be obtained of sharp points is 25-50 CI~~~~~. L G Nekrasov et al, USSR futmt puhlcl 9ih Feh 1972.
(in pulses). No 320852,
A convenient
numbet-
uppl 8/h Jmw 1970,
31 754. Ultrasonic device for the coating of oxide and other types of cathodes. (USSR) An ultrasonic device for atomizing highly-dispersed solids and depositing these in the form of a thin film on, for example, oxidecoated or other types of cathode is described. The material in question is prepared in the form of a suspension which is fed into the chamber subject to the ultrasonic vibrations by means of an electric pumping system. Cathodes coated with the material prepared in the ultrasonic device have much better properties than those based on the use of air-pulverised coating material. The same device may be used in other cases in which it is desired to obtain smooth and compact coatings, for example, in the production of photoresistors. S I Zilitinkovich, M D Gurevich, and G A Fedotov, Gc,rc~ul Proh/~w.c Relatitq to Instrrrrnmt Making. Leninqrad Inst Fine Mcch and Opticr (irr Rmriarr). 31 755. Grid of an electrical vacuum device. (USSR) A new type of grid for electronic valves and other devices is proposed. The grid is made in the form of a wire core with a finer wire wound around it (diameter ratio 2250). This configuration increases the emissivity of the grid and hence reducing its working temperature. The core and winding may be soldered together with special solders and/or provided with comparatively low-temperature coatings (silver, tin, etc.). In this way the amount of power which may be allowed to reach the grid and be duly dissipated by the latter increases. This construction is particularly useful for work in conjunction with oxide-coated cathodes. M M Pogorel’skii and E I Sokolovskii, USSR Putcwt No 319970, uppl27rh May 1969, puhld 20th Jail 1972. 31 756. Composition for filling the cathode-heater space. (USSR) A new composition for filling the gap between the heater and cathode of electronic valves and improving the thermal stability of the whole unit is proposed. The composition dithers from its predecessors in that it contains up to 107: of an active metal, such as titanium OI tantalum, which on heating absorbs hydrogen, expands, and compensates the normal shrinkage of the filler material which occurs on sintering. The exact proportion or active metal to be used may be calculated in advance from a consideration of the dimensions of the space to be filled. A A Vostrov et al, USSR Patent No 331444, uppl 9111 Jnly 1970, prrhld l7tl1 April 1972. 31 757. Method of making a thermionic cathode. (USSR) A method of making a thermionic cathode with an emitting coating of great uniformity and purity is proposed. This is done by depositing the active material from the gas phase by the dissociation of its chloride; additions designed to improve the mobility of the atoms and also the emission characteristics may be deposited in the same way. A typical emitting material which may be prepared in this way is thorium, with zirconium as an additive and tungsten as a base material. It is essential in order to achieve success that the temperature conditions should be carefully regulated so as to achieve the right degree of dissociation of the chlorides and an optimum interaction between the constituent metals. One important advantage of the procedure envisaged is that activation takes place at the working temperature, and this improves the mechanical characteristics of the cathode as a whole. M A Chistyakova et al, USSR Pufent No 327535, ~~~16th Jnly 1970. pdld 17th March 1972. 31 758. Thermocompression welding of metalloceramic parts of electrica I vacuum apparatus. (USSR) The thermocompression welding of metalloceramic parts in the electron guns of various tupes of electrical vacuum apparatus is described. An essential part of the preparatory work is that of providing the metal parts with a high surface finish and removing all traces of grease with trichloroethylene. The actual welding operation takes place in a hydrogen furnace at 95O’C and in typical
abstracts
747-758
30 747. Photographic registration of field injected electrons. (Germany) Direct evidence is presented for the photographic action of held injected electrons into an evaporated layer of silver bromide, with thickness of 0.5 pm, from semiconductor gallium arsenide substrate. (Bulgaria) V Zhelev et al, Whys Srat Sol (a), 10 (I), March 1972, K5-K7. 30 748. Influence of pressure on the electronic conduction in tetrahedrally bonded amorphous semiconductors. (Germany) The influence of uniaxial elastic deformation on the conduction in thin films of tetrahedrally bonded amorphous semiconductors Ge, Si and 111-V compounds is investigated as a function of temperature for stress parallel and perpendicular to the current direction. The amorphous films were prepared by evaporation on cooled substrates in a vacuum of about IO-” torr. W Fuchs, Phys Stat Sol (a), 10 (I ), March 1972, 201-207. 30 749. Semiconductivity in chromium (111) trisacetylacetone. (Germany) Thin films of a chromium (Ill) trisacetylacetone complex evaporated in vacuum on collodion or gold are found to be p-type wide-band semiconductors. Current-voltage characteristics in the dark and under illumination are measured. (France) A P Chappe and J I Vargas, Phys Sfut So/ (a), 10 (2), April 1972, 543-554. 30 750. Germanium films on sapphire and germanium substrates. (Germany) Germanium films were prepared by electron beam evaporation of intrinsic germanium at residual gas pressure less than IO-’ torr with the deposition rate of IO3 Ajmin on substrates kept at temperatures ranging from 700 to 8OO’C. The germanium films deposited simultaneously on sapphire and single crystal germanium substrates appear to have the same electrical transport properties. These results are in contrast to the observed crystalline structure, which show coherent crystalline film growth on germanium crystals while films on sapphire are polycrystalline with random crystallite orientation. Conduction in germanium films on germanium substrates is satisfactorily described by a composite conduction model in which the film is separated from the substrate by an interface barrier layer. (Norway) J S Johannessen, Whys Stat So/ (a), 10 (2), April 1972, 569-580. 30 751. Negative resistance in organic monomolecular layers sandwiched between metal electrodes, (Germany) Monomolecular layers of cadmium arachide were employed as insulator in sandwich structures Al stripe-insulator-evaporated Au or Al electrode. It is shown that organic films can exhibit lowfrequency differential negative resistance if they are placed in vacuum of 10e3 torr. K H Gundlach and J Kadlec, R1.y.~ Stut Sol (a), 10 (2), April 1972, 371-379. 30 752. Kinetics of phase transformation amorphous stateepolycrystal in films of semiconductors. (USSR) Kinetics of phase transformation amorphous state polycrystal in amorphous film of GeFe with thickness of IO-’ cm, prepared by thermal evaporation in vacuum, is investigated. The films were heated by a powerful light pulse with a rate of IO” grad/s. Phase transition was observed by measurement of electrical conductivity using the ultrahigh frequency contact-less method. V 1 Zaliva and V P Zakharov, Pisfna ZhETF, 15 (I ), 1972, 21-24 (in Russian). 31. EVACUATION
AND
SEALING
31 753. Cathode for devices of the UHF magnetron type. (USSR) An improved cathode construction for use in UHF magnetrons is described. Field-emitters are provided in the form of rows of sharp points or edges placed in regions subject to only slight electron bombardment. The steady electric field created by the anode has an axial component parallel to the external magnetic field. Under the action of this electric field the electrons emitted from the field emitters are accelerated and pass into the interaction space. Some return to the cathode and eject secondary electrons. For a radius of curvature of the sharp points equal to 1 pm and a voltage of 20 kV, an emission 384
current of 20 mA may be obtained of sharp points is 25-50 CI~~~~~. L G Nekrasov et al, USSR futmt puhlcl 9ih Feh 1972.
(in pulses). No 320852,
A convenient
numbet-
uppl 8/h Jmw 1970,
31 754. Ultrasonic device for the coating of oxide and other types of cathodes. (USSR) An ultrasonic device for atomizing highly-dispersed solids and depositing these in the form of a thin film on, for example, oxidecoated or other types of cathode is described. The material in question is prepared in the form of a suspension which is fed into the chamber subject to the ultrasonic vibrations by means of an electric pumping system. Cathodes coated with the material prepared in the ultrasonic device have much better properties than those based on the use of air-pulverised coating material. The same device may be used in other cases in which it is desired to obtain smooth and compact coatings, for example, in the production of photoresistors. S I Zilitinkovich, M D Gurevich, and G A Fedotov, Gc,rc~ul Proh/~w.c Relatitq to Instrrrrnmt Making. Leninqrad Inst Fine Mcch and Opticr (irr Rmriarr). 31 755. Grid of an electrical vacuum device. (USSR) A new type of grid for electronic valves and other devices is proposed. The grid is made in the form of a wire core with a finer wire wound around it (diameter ratio 2250). This configuration increases the emissivity of the grid and hence reducing its working temperature. The core and winding may be soldered together with special solders and/or provided with comparatively low-temperature coatings (silver, tin, etc.). In this way the amount of power which may be allowed to reach the grid and be duly dissipated by the latter increases. This construction is particularly useful for work in conjunction with oxide-coated cathodes. M M Pogorel’skii and E I Sokolovskii, USSR Putcwt No 319970, uppl27rh May 1969, puhld 20th Jail 1972. 31 756. Composition for filling the cathode-heater space. (USSR) A new composition for filling the gap between the heater and cathode of electronic valves and improving the thermal stability of the whole unit is proposed. The composition dithers from its predecessors in that it contains up to 107: of an active metal, such as titanium OI tantalum, which on heating absorbs hydrogen, expands, and compensates the normal shrinkage of the filler material which occurs on sintering. The exact proportion or active metal to be used may be calculated in advance from a consideration of the dimensions of the space to be filled. A A Vostrov et al, USSR Patent No 331444, uppl 9111 Jnly 1970, prrhld l7tl1 April 1972. 31 757. Method of making a thermionic cathode. (USSR) A method of making a thermionic cathode with an emitting coating of great uniformity and purity is proposed. This is done by depositing the active material from the gas phase by the dissociation of its chloride; additions designed to improve the mobility of the atoms and also the emission characteristics may be deposited in the same way. A typical emitting material which may be prepared in this way is thorium, with zirconium as an additive and tungsten as a base material. It is essential in order to achieve success that the temperature conditions should be carefully regulated so as to achieve the right degree of dissociation of the chlorides and an optimum interaction between the constituent metals. One important advantage of the procedure envisaged is that activation takes place at the working temperature, and this improves the mechanical characteristics of the cathode as a whole. M A Chistyakova et al, USSR Pufent No 327535, ~~~16th Jnly 1970. pdld 17th March 1972. 31 758. Thermocompression welding of metalloceramic parts of electrica I vacuum apparatus. (USSR) The thermocompression welding of metalloceramic parts in the electron guns of various tupes of electrical vacuum apparatus is described. An essential part of the preparatory work is that of providing the metal parts with a high surface finish and removing all traces of grease with trichloroethylene. The actual welding operation takes place in a hydrogen furnace at 95O’C and in typical