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712. Secondary emission and elastic reflection of electrons from single crystals
Classified
abstracts
701-712
18 701. The combination of Auger spectroscopy and characteristic loss spectroscopy for the elements V to Co. (Germany) Splitting of the M,,, characteristic loss peak has been observed following oxidation of clean Cr and V surfaces, but not after oxidation of Fe and Co, although in all four cases the Auger spectra were characteristic for an oxidized surface. In addition, even when the Cr Auger spectrum indicated a clean surface, the M,,, loss peak was found to have a position and width different from those expected for a clean metal. The results are explained on the assumption of different ranges for electrons of different origins. The characteristic loss electrons do have a significantly greater range than Auger electrons of the same energy and of course a very much greater range than the lowenergy Auger electrons. When a clean surface of Fe or Co is exposed to oxygen at room temperature, a monolayer of oxide is formed at the surface, and the resulting Auger spectrum is similar to that of a bulk oxide. The characteristic loss spectrum is, however, unaffected. Cr and V, on the other hand, oxidize more readily at room temperature, resulting presumably, in a thicker oxide layer at the surface. J P Coad and J C Riviere, Ph_~sStat Sol (a), 7 (2), Ocr 1971, 571-575. 18 702. Efficient electron emitter employing hollow cathode discharge. (USSR) A special gas-discharge system is described which employs a hollow cathode of MO tube 20 mm in length and 8 mm in diameter as an efficient electron emitter. The minimum pressure at which discharge could be maintained was 2.5 torr. A method for the transport of a high-density electron current, without significant losses, through regions with a discrete pressure drop from 0.4 to lOma torr, is presented. The maximum density of the electron current was 300 A/cm2 with an electron energy spread of 0 to 60 eV. V A Popov et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 327-329 (in Russian). 18 703. Intensities of Auger and photoelectron spectra. (USSR) Intensities of Auger and photoelectron spectra of elemental emitters in a bulk polycrystalline target and of a surface monolayer deposited on a bulk substrate are calculated for ionization by X-ray photons and electrons with energies of 1 to 50 keV. A G Stadnikov and A P Nikolskiy, Izv AN SSSR Ser Fiz, 35 (2), 1971, 33CL333 (in Russian). 18 704. Model of the oxide cathode with surface donor centres. (USSR) An analysis of data on nature of chemical bond and electron state of donor centres in crystals of alkaline-earth metal oxides is presented. A new model of thermionic emission in ionic crystals is given. Surface donor centres close to the vacuum level are formed on the surface of an oxide cathode as a result of vacuum treatment including thermal, chemical and current activation. B P Nikonov, Izv AN SSSR Ser Fiz, 35 (2), 1971,270-278 (in Russian). 18 705. Investigation of influence of surface states on thermionic properties of alkaline-earth metal oxides. (USSR) influence of surface states generated by barium deposition on the thermionic properties of alkaline-earth metal oxides is investigated in an experimental device at 1 x IO-” torr. A linear dependence of the emission current on the concentration of surface donor centres of two types, 1 .O and 1.4 eV below the vacuum level, is found. K S Beynar and B P Nikonov, Izv AN SSSR Ser Fiz, 35 (2), 197 1,286290 (in Russian). 18 706. Thermionic parameters of (111) and (110) faces of single crystal W covered with Ge film. (USSR) Thermionic parameters of spherical tungsten single crystals are investigated in a sealed device at 1 x IO-* torr during deposition of Ge on W crystal. It is shown that during adsorption of Ge on (111) and (110) faces of single crystal W the density of the thermionic current decreases due to a considerable decrease in the thermionic constant of the Richardson equation. V Kh Burkhanova and N A Gorhatyy, Izv AN SSSR Ser Fiz, 35 (2), 197 I, 291-292 (in Ru.wan). 18 707. The problem of instability of the electron emission from thin dispersed gold films activated by barium oxide (Au-BaO). (USSR) Causes of instability of the emission current of hot electrons from a
gap system containing gold film activated by BaO are considered. Evaporation of the dispersed gold film and activation of its surface by several BaO monolayers was performed in a sealed device at residual gas pressure below 10e7 torr. It is found that the decrease of the power fed to the film due to an increase in its resistance forms the main cause of the emission current decay. A S Sukhariev and S V Zagrebneva, Izv AN SSSR Ser Fiz, 35 (2), 1971, 298-301 (in Russian). 18 708. Secondary electron emission of W and MO single crystals. (USSR) A systematic experimental study of secondary emission characteristics of W and MO single crystals at low and elevated temperatures is carried out in sealed devices at residual gas pressures below 1O-8 torr. Experimental results are discussed. M V Gomoyunova and B Z Aliev, izv AN SSSR Seu Fiz, 35 (2), 1971, 231-236 (in Russian). 18 709. Positive surface ionization of atoms of alkali metals and their halide compounds. (USSR) Positive surface ionization of K atoms and KCI, KI and CsCl molecules on the (100) face of W is investigated in sealed devices at pressures below 1 x 1Om8 torr. Two maxima are found on the plot of the ion current vs the density of ionizing molecular flow of alkali halide compounds, while only one maximum is observed on the plot of alkali atoms. An explanation of this phenomena is presented. E F Chaykovskiy et al, Zzv AN SSSR Ser Fiz, 35 (2), 1971, 373-378 (i/r Russian). 18 710. Some characteristics and emission mechanism of a zirconium carbide thermionic cathode. (USSR) ZrC offers potential use as cathode material in thermionic energy converters and magnetohydrodynamic generators due to its stability at high temperatures. ZrC was prepared by reduction of ZrO by charcoal mixed in stoichiometric composition in argon atmosphere at 2600’ C. It is found that pure ZrC has an effective work function 4.05 eV at temperature of 1800°K in vacuum. In argon ambient up to lo-” torr the emission current does not change. In potassium and caesium vapours the emission current from ZrC increases considerably. Emission properties with additions of MO and Ti and with deposited metallic films of Zr on the cathode surface are also investigated. Theoretical analysis and the experimental data on the thermionic emission from ZrC in vacuum, argon and alkali metal vapours indicate that the emission mechanism is of a metallic character and is governed by a Zr film on the surface of ZrC. Kh S Kan and B S Kulvarskaya, Zzv AN SSSR Ser Fiz, 35 (2), 1971, 279-285 (in Russian). 18 711. Field electron emission of monocrystalline lanthanum hexaboride. (USSR) Field electron emission of LaB, is investigated in the range - 196 to 5OO’C. The experiments were performed in a glass sealed field electron microscope containing also a manometric system and tantalum getter. LaB, tius with curvature radius of 5OCO to 7000 8, were prepared by electrol;tic etching. A residual gas pressure of lo-” torr was attained in the device after careful degassing and getter evaporation. Influence of the residual gases on the operation of a LaB, field emitter was investigated at lo-’ to 1Oms torr. The residual gas contained mainly nitrogen as was confirmed from the tungsten emission patterns. It is found that the field emission current is markedly reduced at lo-’ torr. Simultaneously with the emission current decrease a decrease in the brightness of emission patterns of the LaB, single crystal is observed. All the experimental data can be explained by the existence on the surface of free lanthanum atoms not bound to the LaB, lattice. G A Kudintseva et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 293-297 (in Russian). 18 712. Secondary emission and elastic reflection of electrons from single crystals. (USSR) The angular dependencies of the coefficients of secondary emission, inelastically and elastically reflected electrons are investigated over a wide range of energies from a few tens to a few thousand evofprimary electrons. The influence of target temperature and energy spectra of secondary electrons at various incidence angles of the primary electrons are investigated for single crystal molybdenum, tungsten 241
Classified
abstracts
713-722
and niobium, prepared by zone melting. The measurements were carried out in sealed devices of quasi-spherical capacitor type with an antidynatron grid, at a residual gas pressure of 5x IO-” torr. The samples were mechanically polished, chemically and electrolytically etched and cleaned by prolonged heating at 1900 to 2000°C in vacu~~n~. It is found that ordering of the crystal lattice influences all basic secondary emission characteristics. Causes of the fine structure of measured secondary emission characteristics are discussed. A R Shulman et al. /ZI, AN SSSR Seu Fiz, 35 (2), 1971, 218-224 (i/r Ri/.\siu/r). 18 713. Secondary emission properties of oxide layers on the surface of activated alloys containing Li and Mg. (USSR) Results of an experimental investigation of the secondary emission properties of aluminium alloys containing Li and Mg are reported. The various activation regimes were studied on a continuously pumped vacuum system, and the basic secondary emission properties were investigated in sealed devices at a residual gas pressure of I IO-” torr. An increase of pressure to IOeR torr did not markedly influence the properties of the emitters. The highest coefficient of secondary electron emission, of the order of 30, was exhibited by alloys containing 0.05 to 0.15 per cent of Li and 0.5 to 1 per cent of M.g and activated at sufficiently high temperature (600 to 64O’C). It is assumed that MgO in the complex oxide system on the surface of activated Al-Li-Mg alloy plays a basic role in the enhancement of the secondary emission yield. The role of lithium is assumed to be in reducing the electron affinity due to formation of a thin, nearly monomolecular, lithium oxide film on the surface of MgO layers and grains. G V Stchinskiy, Izl; AN SSSR Ser Fiz, 35 (2), 1971, 237-241 (01 R/r.sXiu/r). I8 714. Field enhanced secondary emission of new low-voltage efficient emitters of porous layers of dielectrics. (USSR) The effect of thickness on the field enhanced transmission secondary electron emission are investigated for porous alkali halide emitters. Using CsI porous layers, low-voltage efficient emitters were prepared with transmission electron emission threshold at I keV and secondary electron emission coefficient of I5 to 45 at primary electron energy of 3 kcV. The porous dielectric layers were prepared by evaporation of salts in inert gas (in nitrogen at a pressure of the order of few tens of torr, and in argon at 2 to 4 torr). Inertia-less field enhanced secondary electron emission was observed for all emitters. The energy distribution of electrons emitted during transmission secondary emission is measured for the Csl layers. The surface potential of KCI layers is measured using an electron-beam voltmeter. The formation of inertial and inertia-less components of the secondary emission is observed in KCI and LiF layers. A P Balashova et al, Izv AN SSSR Srr Fiz, 35 (2), 1Y7 1, 242-247 (in R//.wiU/!). 18 715. Conductivity on the surface of grains in porous semiconducting oxides. (USSR) Results are presented of investigations on electrical conductivity, thermoelectromotive force, thermal conductivity and thermionic emission of porous barium-strontium-calcium oxides and single crystals of barium, strontium and calcium oxides in vacuum and in atmosphere of barium, caesium and magnesium vapours. An experimental device for investigating the influence of barium, caesium and magnesium vapours on these oxides is described. The experimental data confirm the hypothesis that in porous barium-strontiumcalcium oxides at low temperatures, when the role of electron gas in pores is not important, a basic conductivity is formed on the surface of the grains. It is shown that the observed phenomena cannot be explained by conductivity in the surface zone. It is supposed that the electrical conductivity is not caused by free surface electrons but that it arises as a result of phonon induced transitions of electrons from filled to unoccupied localized surface donor states, ie surface impurity conductivity predominantly by S- and S’centrcs takes place. N N Kovalev et al, F/z Twtd T&I, 13 (8). 1971, 2364-2370 (in R~ssicm). I8 :30 716. Photo-field emission from thin cadmium sulphide films on tungsten. (Germany) f+uperimcntal results of inbsestigation of photo-field emission from 242
thin cadmium sulphidc films. vacuum evaporated on tungsten are considered. (USSR) R M Khatapova and I L Sokolskaya, P/I.I,sStat Sol (a), 8 (I), NOV 1971, K51LK53.
II.
Vacuum
22. PUMPS
apparatus
and auxiliaries
AND PUMP FLUIDS
22 717. Partial pressure analyses by means of a quadrupole residual gas (Germany) analyzer and computer programme. A computer programme is presented for evaluating residual gas composition and total pressure in vacuum systems. The residual gas spectrum was determined by quadrupole residual gas analyzer and the nitrogen equivalent total pressure by hot cathode ionization gauge. For the data evaluation the computer programme SGAP was developed. Determination of the “cracking pattern” and the “sensitivity” is described and the structure of the programme explained. The reliability of the method and the magnitude of errors in the residual gas composition are demonstrated by a number of examples. R Dobrozemsky and W Farber, Vakuum-Techtrik, 20 (S), Dee 1971, 23 I-239 (in Gevma/r). 22 718. Development of a standard apparatus for measurement of total and partial pressures in the regions of high and ultrahigh vacuum. (USSR) The standard apparatus, with a base pressure of 3 .d IO-” Pa, consists of a preliminary pumping system, a cryogenic aggregate, and IOOlitre working volume. The preliminary pumping system contains a forevacuum pump filled with high-vacuum oil, valves, forevacuum forevacuum gauges, oil diffusion trap cooled by liquid nitrogen, pumps and a sorption trap. The preliminary pumping system is connected to the cryogenic aggregate by means of a bakeable highvacuum valve. The cryogenic aggregate contains a needle valve, condensation pumps and ultrahigh vacuum gauges, and is connected to the working chamber by means of a bakeable ultrahigh-vacuum valve. The working chamber contains a condensation pump, a needle valve, ultrahigh vacuum gauges and an omegatron partial pressure analyzer. The standard vacuum apparatus provides unity of pressure in the region of 10e3 to IO-” Pa of absolute total pressure and in the range of IO-” to IO-” Pa of partial pressure. M A Gulyaev and A V Eryukhin, Izmerir Tekh, No I I, 1971, 29-33 (i/r Russicm). 22 719. Liquid multi-impulse micromanometer. (USSR) A battery micromanometer is described, in which the collector and the measuring capillaries are made as a unit. Booster oil is used as working liquid. The measuring tubes can be inclined at an arbitrary angle. The described battery micromanometer with an absolute error of ho.44 Pa was employed for investigating gas dynamic processes in a model of vacuum equipment for refining of tin. The absolute pressure was determined with the aid of a McLeod gauge. A 1 Chernogolov et al, Izmevit Tekh, No 8, 1971, 88-89 (i/r Ru~ian). 22 720. Compression piston gauge. (USSR) Construction of a piston gauge is described, which is based on rarefaction and compression of the measured gas. The gauge permits measurement of absolute pressures below atmospheric down to 2.66 Pa with an error not greater than 0.5 per cent. It can be used as portable standard gauge and does not require a pumping system. G I Polukhin and V A Ryzhov, Izmerif Tekh, No 8, 197 I, 89-W (it/ Russiu,r). 22 (USSR) 721. Composite gauge for measurement of absolute pressures. An absolute mercury gauge with digital indication is described and examined. In the collector, a pressure below I .33 Pa is maintained by a forevacuum pump and monitored by a thermocouple gauge. Six Utube manometers are connected to the collector. The mercury level in 8 mm manometric tubes is measured with the aid of steel balls floating on the mercury level and movable differential transformers. S A Safronnikov, Jzmcrit Tckh, No 9, I97 I , IO1 I02 (in R~~wiun). 22 722, Utilization of vacuum contact-less thermal converters for measurement of pressure. (USSR) Experiments carried out haue shown that the contact-lcs\ thermo-
abstracts
701-712
18 701. The combination of Auger spectroscopy and characteristic loss spectroscopy for the elements V to Co. (Germany) Splitting of the M,,, characteristic loss peak has been observed following oxidation of clean Cr and V surfaces, but not after oxidation of Fe and Co, although in all four cases the Auger spectra were characteristic for an oxidized surface. In addition, even when the Cr Auger spectrum indicated a clean surface, the M,,, loss peak was found to have a position and width different from those expected for a clean metal. The results are explained on the assumption of different ranges for electrons of different origins. The characteristic loss electrons do have a significantly greater range than Auger electrons of the same energy and of course a very much greater range than the lowenergy Auger electrons. When a clean surface of Fe or Co is exposed to oxygen at room temperature, a monolayer of oxide is formed at the surface, and the resulting Auger spectrum is similar to that of a bulk oxide. The characteristic loss spectrum is, however, unaffected. Cr and V, on the other hand, oxidize more readily at room temperature, resulting presumably, in a thicker oxide layer at the surface. J P Coad and J C Riviere, Ph_~sStat Sol (a), 7 (2), Ocr 1971, 571-575. 18 702. Efficient electron emitter employing hollow cathode discharge. (USSR) A special gas-discharge system is described which employs a hollow cathode of MO tube 20 mm in length and 8 mm in diameter as an efficient electron emitter. The minimum pressure at which discharge could be maintained was 2.5 torr. A method for the transport of a high-density electron current, without significant losses, through regions with a discrete pressure drop from 0.4 to lOma torr, is presented. The maximum density of the electron current was 300 A/cm2 with an electron energy spread of 0 to 60 eV. V A Popov et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 327-329 (in Russian). 18 703. Intensities of Auger and photoelectron spectra. (USSR) Intensities of Auger and photoelectron spectra of elemental emitters in a bulk polycrystalline target and of a surface monolayer deposited on a bulk substrate are calculated for ionization by X-ray photons and electrons with energies of 1 to 50 keV. A G Stadnikov and A P Nikolskiy, Izv AN SSSR Ser Fiz, 35 (2), 1971, 33CL333 (in Russian). 18 704. Model of the oxide cathode with surface donor centres. (USSR) An analysis of data on nature of chemical bond and electron state of donor centres in crystals of alkaline-earth metal oxides is presented. A new model of thermionic emission in ionic crystals is given. Surface donor centres close to the vacuum level are formed on the surface of an oxide cathode as a result of vacuum treatment including thermal, chemical and current activation. B P Nikonov, Izv AN SSSR Ser Fiz, 35 (2), 1971,270-278 (in Russian). 18 705. Investigation of influence of surface states on thermionic properties of alkaline-earth metal oxides. (USSR) influence of surface states generated by barium deposition on the thermionic properties of alkaline-earth metal oxides is investigated in an experimental device at 1 x IO-” torr. A linear dependence of the emission current on the concentration of surface donor centres of two types, 1 .O and 1.4 eV below the vacuum level, is found. K S Beynar and B P Nikonov, Izv AN SSSR Ser Fiz, 35 (2), 197 1,286290 (in Russian). 18 706. Thermionic parameters of (111) and (110) faces of single crystal W covered with Ge film. (USSR) Thermionic parameters of spherical tungsten single crystals are investigated in a sealed device at 1 x IO-* torr during deposition of Ge on W crystal. It is shown that during adsorption of Ge on (111) and (110) faces of single crystal W the density of the thermionic current decreases due to a considerable decrease in the thermionic constant of the Richardson equation. V Kh Burkhanova and N A Gorhatyy, Izv AN SSSR Ser Fiz, 35 (2), 197 I, 291-292 (in Ru.wan). 18 707. The problem of instability of the electron emission from thin dispersed gold films activated by barium oxide (Au-BaO). (USSR) Causes of instability of the emission current of hot electrons from a
gap system containing gold film activated by BaO are considered. Evaporation of the dispersed gold film and activation of its surface by several BaO monolayers was performed in a sealed device at residual gas pressure below 10e7 torr. It is found that the decrease of the power fed to the film due to an increase in its resistance forms the main cause of the emission current decay. A S Sukhariev and S V Zagrebneva, Izv AN SSSR Ser Fiz, 35 (2), 1971, 298-301 (in Russian). 18 708. Secondary electron emission of W and MO single crystals. (USSR) A systematic experimental study of secondary emission characteristics of W and MO single crystals at low and elevated temperatures is carried out in sealed devices at residual gas pressures below 1O-8 torr. Experimental results are discussed. M V Gomoyunova and B Z Aliev, izv AN SSSR Seu Fiz, 35 (2), 1971, 231-236 (in Russian). 18 709. Positive surface ionization of atoms of alkali metals and their halide compounds. (USSR) Positive surface ionization of K atoms and KCI, KI and CsCl molecules on the (100) face of W is investigated in sealed devices at pressures below 1 x 1Om8 torr. Two maxima are found on the plot of the ion current vs the density of ionizing molecular flow of alkali halide compounds, while only one maximum is observed on the plot of alkali atoms. An explanation of this phenomena is presented. E F Chaykovskiy et al, Zzv AN SSSR Ser Fiz, 35 (2), 1971, 373-378 (i/r Russian). 18 710. Some characteristics and emission mechanism of a zirconium carbide thermionic cathode. (USSR) ZrC offers potential use as cathode material in thermionic energy converters and magnetohydrodynamic generators due to its stability at high temperatures. ZrC was prepared by reduction of ZrO by charcoal mixed in stoichiometric composition in argon atmosphere at 2600’ C. It is found that pure ZrC has an effective work function 4.05 eV at temperature of 1800°K in vacuum. In argon ambient up to lo-” torr the emission current does not change. In potassium and caesium vapours the emission current from ZrC increases considerably. Emission properties with additions of MO and Ti and with deposited metallic films of Zr on the cathode surface are also investigated. Theoretical analysis and the experimental data on the thermionic emission from ZrC in vacuum, argon and alkali metal vapours indicate that the emission mechanism is of a metallic character and is governed by a Zr film on the surface of ZrC. Kh S Kan and B S Kulvarskaya, Zzv AN SSSR Ser Fiz, 35 (2), 1971, 279-285 (in Russian). 18 711. Field electron emission of monocrystalline lanthanum hexaboride. (USSR) Field electron emission of LaB, is investigated in the range - 196 to 5OO’C. The experiments were performed in a glass sealed field electron microscope containing also a manometric system and tantalum getter. LaB, tius with curvature radius of 5OCO to 7000 8, were prepared by electrol;tic etching. A residual gas pressure of lo-” torr was attained in the device after careful degassing and getter evaporation. Influence of the residual gases on the operation of a LaB, field emitter was investigated at lo-’ to 1Oms torr. The residual gas contained mainly nitrogen as was confirmed from the tungsten emission patterns. It is found that the field emission current is markedly reduced at lo-’ torr. Simultaneously with the emission current decrease a decrease in the brightness of emission patterns of the LaB, single crystal is observed. All the experimental data can be explained by the existence on the surface of free lanthanum atoms not bound to the LaB, lattice. G A Kudintseva et al, Izv AN SSSR Ser Fiz, 35 (2), 1971, 293-297 (in Russian). 18 712. Secondary emission and elastic reflection of electrons from single crystals. (USSR) The angular dependencies of the coefficients of secondary emission, inelastically and elastically reflected electrons are investigated over a wide range of energies from a few tens to a few thousand evofprimary electrons. The influence of target temperature and energy spectra of secondary electrons at various incidence angles of the primary electrons are investigated for single crystal molybdenum, tungsten 241
Classified
abstracts
713-722
and niobium, prepared by zone melting. The measurements were carried out in sealed devices of quasi-spherical capacitor type with an antidynatron grid, at a residual gas pressure of 5x IO-” torr. The samples were mechanically polished, chemically and electrolytically etched and cleaned by prolonged heating at 1900 to 2000°C in vacu~~n~. It is found that ordering of the crystal lattice influences all basic secondary emission characteristics. Causes of the fine structure of measured secondary emission characteristics are discussed. A R Shulman et al. /ZI, AN SSSR Seu Fiz, 35 (2), 1971, 218-224 (i/r Ri/.\siu/r). 18 713. Secondary emission properties of oxide layers on the surface of activated alloys containing Li and Mg. (USSR) Results of an experimental investigation of the secondary emission properties of aluminium alloys containing Li and Mg are reported. The various activation regimes were studied on a continuously pumped vacuum system, and the basic secondary emission properties were investigated in sealed devices at a residual gas pressure of I IO-” torr. An increase of pressure to IOeR torr did not markedly influence the properties of the emitters. The highest coefficient of secondary electron emission, of the order of 30, was exhibited by alloys containing 0.05 to 0.15 per cent of Li and 0.5 to 1 per cent of M.g and activated at sufficiently high temperature (600 to 64O’C). It is assumed that MgO in the complex oxide system on the surface of activated Al-Li-Mg alloy plays a basic role in the enhancement of the secondary emission yield. The role of lithium is assumed to be in reducing the electron affinity due to formation of a thin, nearly monomolecular, lithium oxide film on the surface of MgO layers and grains. G V Stchinskiy, Izl; AN SSSR Ser Fiz, 35 (2), 1971, 237-241 (01 R/r.sXiu/r). I8 714. Field enhanced secondary emission of new low-voltage efficient emitters of porous layers of dielectrics. (USSR) The effect of thickness on the field enhanced transmission secondary electron emission are investigated for porous alkali halide emitters. Using CsI porous layers, low-voltage efficient emitters were prepared with transmission electron emission threshold at I keV and secondary electron emission coefficient of I5 to 45 at primary electron energy of 3 kcV. The porous dielectric layers were prepared by evaporation of salts in inert gas (in nitrogen at a pressure of the order of few tens of torr, and in argon at 2 to 4 torr). Inertia-less field enhanced secondary electron emission was observed for all emitters. The energy distribution of electrons emitted during transmission secondary emission is measured for the Csl layers. The surface potential of KCI layers is measured using an electron-beam voltmeter. The formation of inertial and inertia-less components of the secondary emission is observed in KCI and LiF layers. A P Balashova et al, Izv AN SSSR Srr Fiz, 35 (2), 1Y7 1, 242-247 (in R//.wiU/!). 18 715. Conductivity on the surface of grains in porous semiconducting oxides. (USSR) Results are presented of investigations on electrical conductivity, thermoelectromotive force, thermal conductivity and thermionic emission of porous barium-strontium-calcium oxides and single crystals of barium, strontium and calcium oxides in vacuum and in atmosphere of barium, caesium and magnesium vapours. An experimental device for investigating the influence of barium, caesium and magnesium vapours on these oxides is described. The experimental data confirm the hypothesis that in porous barium-strontiumcalcium oxides at low temperatures, when the role of electron gas in pores is not important, a basic conductivity is formed on the surface of the grains. It is shown that the observed phenomena cannot be explained by conductivity in the surface zone. It is supposed that the electrical conductivity is not caused by free surface electrons but that it arises as a result of phonon induced transitions of electrons from filled to unoccupied localized surface donor states, ie surface impurity conductivity predominantly by S- and S’centrcs takes place. N N Kovalev et al, F/z Twtd T&I, 13 (8). 1971, 2364-2370 (in R~ssicm). I8 :30 716. Photo-field emission from thin cadmium sulphide films on tungsten. (Germany) f+uperimcntal results of inbsestigation of photo-field emission from 242
thin cadmium sulphidc films. vacuum evaporated on tungsten are considered. (USSR) R M Khatapova and I L Sokolskaya, P/I.I,sStat Sol (a), 8 (I), NOV 1971, K51LK53.
II.
Vacuum
22. PUMPS
apparatus
and auxiliaries
AND PUMP FLUIDS
22 717. Partial pressure analyses by means of a quadrupole residual gas (Germany) analyzer and computer programme. A computer programme is presented for evaluating residual gas composition and total pressure in vacuum systems. The residual gas spectrum was determined by quadrupole residual gas analyzer and the nitrogen equivalent total pressure by hot cathode ionization gauge. For the data evaluation the computer programme SGAP was developed. Determination of the “cracking pattern” and the “sensitivity” is described and the structure of the programme explained. The reliability of the method and the magnitude of errors in the residual gas composition are demonstrated by a number of examples. R Dobrozemsky and W Farber, Vakuum-Techtrik, 20 (S), Dee 1971, 23 I-239 (in Gevma/r). 22 718. Development of a standard apparatus for measurement of total and partial pressures in the regions of high and ultrahigh vacuum. (USSR) The standard apparatus, with a base pressure of 3 .d IO-” Pa, consists of a preliminary pumping system, a cryogenic aggregate, and IOOlitre working volume. The preliminary pumping system contains a forevacuum pump filled with high-vacuum oil, valves, forevacuum forevacuum gauges, oil diffusion trap cooled by liquid nitrogen, pumps and a sorption trap. The preliminary pumping system is connected to the cryogenic aggregate by means of a bakeable highvacuum valve. The cryogenic aggregate contains a needle valve, condensation pumps and ultrahigh vacuum gauges, and is connected to the working chamber by means of a bakeable ultrahigh-vacuum valve. The working chamber contains a condensation pump, a needle valve, ultrahigh vacuum gauges and an omegatron partial pressure analyzer. The standard vacuum apparatus provides unity of pressure in the region of 10e3 to IO-” Pa of absolute total pressure and in the range of IO-” to IO-” Pa of partial pressure. M A Gulyaev and A V Eryukhin, Izmerir Tekh, No I I, 1971, 29-33 (i/r Russicm). 22 719. Liquid multi-impulse micromanometer. (USSR) A battery micromanometer is described, in which the collector and the measuring capillaries are made as a unit. Booster oil is used as working liquid. The measuring tubes can be inclined at an arbitrary angle. The described battery micromanometer with an absolute error of ho.44 Pa was employed for investigating gas dynamic processes in a model of vacuum equipment for refining of tin. The absolute pressure was determined with the aid of a McLeod gauge. A 1 Chernogolov et al, Izmevit Tekh, No 8, 1971, 88-89 (i/r Ru~ian). 22 720. Compression piston gauge. (USSR) Construction of a piston gauge is described, which is based on rarefaction and compression of the measured gas. The gauge permits measurement of absolute pressures below atmospheric down to 2.66 Pa with an error not greater than 0.5 per cent. It can be used as portable standard gauge and does not require a pumping system. G I Polukhin and V A Ryzhov, Izmerif Tekh, No 8, 197 I, 89-W (it/ Russiu,r). 22 (USSR) 721. Composite gauge for measurement of absolute pressures. An absolute mercury gauge with digital indication is described and examined. In the collector, a pressure below I .33 Pa is maintained by a forevacuum pump and monitored by a thermocouple gauge. Six Utube manometers are connected to the collector. The mercury level in 8 mm manometric tubes is measured with the aid of steel balls floating on the mercury level and movable differential transformers. S A Safronnikov, Jzmcrit Tckh, No 9, I97 I , IO1 I02 (in R~~wiun). 22 722, Utilization of vacuum contact-less thermal converters for measurement of pressure. (USSR) Experiments carried out haue shown that the contact-lcs\ thermo-