- Email: [email protected]
Secondary electron emission of alloys of zirconium and hafnium with rhenium
Classified
abstracts
280-292 16 of gases on metals by the Auger process.
280. Study of the adsorption (USA)
The apparatus under construction to measure the degree of surface coverage using the Auger process is described. It will use an electron impact helium ion source, leading to a cylindrical lens which focuses the ions onto the target. The target is a single crystal tungsten ribbon mounted on two heating leads which pass directly into a liquid nitrogen cooling bath. A schematic of the adsorption-desorption experiment is included and the experimental technique is illustrated. D Alpert, Rep NASA-CR-75681; (Illinois Univ Urbana, Coordinated
18. Gaseous
R-286; AD-632596; Science Lab).
April
18 It is concluded that there are at least sixteen variables affecting breakdown in vacuum. Traditional methods of experimenting by varying one parameter at a time would take years to amass the data on which a cohesive theory could be formulated. A pilot experiment was set up based on the statistical approach to experimental design to evaluate the relative importance of each of the variables. The pilot experiment is a partial replica of a two-level full factorial design. It is expected that sufficient information will be collected to permit the elimination of variables having minor effects and to permit a more comprehensive design for the final experiment. Jan 1966 (Army
18 in potassium
and mercury.
(USA)
The resistivity of superheated potassium and mercury vapour was measured. Substantial heating of the gas by the discharge was avoided by flowing the gas through the discharge region. The resistivity of potassium gas at 7.8 Torr pressure, 870°K and 1 A/cm2 is 2.2 ohm cm. The resistivity of mercury gas at 14 Torr, 870°K and 0.67 A/cm2 is 10 ohm cm. The resistance was primarily due to short range electron/neutral atom collisions. The cross section for this process as calculated from the resistivity is 1.5 x lo-” cm” for potassium and 2.5 X 1O~l’ cm* for mercury. C A Guderjahn, Rep AId5-120; AFORS-65-1914; A 0628187, Jul_v I965 (Atomics
International,
Canoga Park, Cal(f). 18
283. Investigation An experimental
of high power gaseous electronics.
(USA)
technique is described for obtaining reproducible clean-up measurements in high power microwave duplexer discharges under controlled conditions. A basic clean-up rate is defined as the number of molecules sorbed per cm3 of discharge/square root of average incident power. Data is given for the clean-up of inert gases in quartz; hydrogen in 7070 glass, quartz, copper, nickel, molybdenum and kovar; and oxygen and bromine in kovar. It was found that life time of duplexers increases with the square of the ratio of gas volume to discharge area and with the square of the pressure range over which a tube remains operable. Life time is also inversely proportional to peak power and to the square of the duty cycle. H S Maddix, Rep AD-629537, Burlington, Mass). 284. A high resolution research. (USA)
Feb 1966 (Microwave
secondary
emission
Associates
spectrometer
Znc
18 : 39 for surface
The possibility of using secondary emission in surface research and the apparatus developed for this research are discussed. The secondary electrons were divided into two groups: primary electrons scattered (elastically or inelastically) from the surface, and electrons excited from the surface by the primaries. It is suggested that the following main areas can be investigated using the elastically scattered electrons: (1) the excitation of the vibrational states of adsorbed gas species on the surface; (2) the electronic transitions of the adsorbed atoms on surfaces; (3) the plasmon excitation by electron impact. Details of the apparatus constructed for high resolution studies are given and schematic diagrams are included. The operation of the monochromator/analyzer system is described and the operating characteristics are shown. Measurements obtained on the (100) surface of a tungsten single crystal ribbon are discussed and the energy distribution of secondary electrons from a contaminated 110
Univ Urbana, Coordinated
Science Lab).
18 285. High frequency discharge in a ring electrode. (USSR) The mechanism of the plasma configuration excitation by a ring electrode hf field was investigated at pressures of 2 x 10m2to 1 torr. A D Andreev et al, Zh Tekh Fiz, 36 (9), Russian).
Sept 1966, 1636-1638
(in
18 regions of the
286. Energy and angle distribution of ions in various cathode in a higb voltage Penning discharge. (USSR)
281. Design of a high voltage breakdown in vacuum experiment. (USA)
282. Flowing gas discharges
(Illinois
1966.
electronics
M N Cbrepta et al, Rep ECOM-2655; AD-628042, Electronics Labs, Fort Monmouth, NJ).
surface, from the surface after exposure to nitrogen and hydrogen and from clean tungsten, are presented. D Alpert, Rep NASA-CR-75681; R-286; AD632596; April 1966
The properties of the Penning discharge were studied with particular reference to the pumping action. It was found that residual gas ions bombard only a narrow area at the cathode centre in the direction perpendicualr to the cathode surface with energies dependent on the pressure. Experiments were performed at the 1O-4 to 1O-Btorr range. 0 K Kurbatov, Zh Tekh Fiz, 36 (9)) Sept 1966,1665-1668 (in Russian). 287. Atomic beam Ionizer as a source of polarized ions.
18 :33 (USSR)
The design of the Zinchenko type hydrogen ionizer with high efficiency (about 4.5 x lo-*) is described. It operates at 1O-8 torr with an oxide cathode as the electron source and hydrogen atom beam intensity is measured by an ionization gauge. 0 I Ekhichev et al, Zh Tekh Fiz, 36 (9), Sept 1966, 1681-1684 (in Russian). 288. Two mechanisms crystals. (USSR)
of photo-stimulated
electron
emission
18 by ion
It is shown that the photo-thermal mechanism of the photo-stimulated electron emission from F-centres of ion crystals is well established only when ion crystals are in a gas atmosphere and that the photoionization mechanism exists alone under high vacuum conditions. A N Belkind et al, Izv Akad Nauk SSSR, Ser Fiz 30 (9), Sept 1966, 1448-1450
(in Russian).
18 :30 289. The effect of backing material on photo-emf in CdTe films. (USSR)
It is known that photo-emf of CdTe thin films depends on the backing material and its temperature during vacuum condensation of the films. Experiments showed that, for AlBOS backing, the CdTe photo-emf more than double that for glass backing. The backing temperature dependence is described. L S Palatnik and V K Sorokin, Fiz Tverd Tela, 8 (9), Sept 1966,27952796 (in Russian). 18 290. Dependence of secondary electron emission and electron elastic reflection on thickness of barium oxide film on tungsten in the case of low energy primary electrons. (USSR)
For primary electrons with energies 3 to 50 eV the depth of secondary electron emission is 16 monolayers and it is not dependent on the primary electron energy. Electron elastic reflection depth is about 5 monolayers and it is not dependent on the primary electron energies in the range 5 to 17 eV. All experiments were made at IO+ torr and carefully baked polycrystal- tungsten was employed as the backing for BaO layers. A R Shul’man and N P Bazhanova, 2797-2798 (in Russian).
Fiz Tverd Tela, 8 (9), Sept. I966
18 :33 291. Measurement of cathode oxide coating electroconductivity and the coating work functions, using a probe. (USSR) Work function of the cathode oxide coatings was found by measuring the electroconductivity of the oxides and its changes in a magnetic field. Advantages of the described method are: the temperature of the probe and the oxide are identical; and the probe position determinations have only slight influence on experimental error. Typical characteristics are given and compared with those obtained by Schottky method. E M Sher, Radiotekh Elektron, 11 (9), Sept 1966, 1721-1723 (in Russian). 18 292. Secondary electron emission of alloys of zirconium and hafnimn with rhenium. (USSR) The influence of the composition of Zr-Re and Hf-Re alloys on the
Classified
abstracts
293-308
secondary electron emission, the primary electron non-elastic reflection and the secondary electrons energy distribution, was studied. L A Ermolaev and B Kh Dvubua. Radiotekh Elektron. , 11 (91. ,,, Scot . 1966, 1724-1728
(in Russian>.
’
18 293. Positive column of helium discharge in a strong magnetic field. (USSR)
The transformation of a He discharge positive column from a laminar convection regime into a turbulent one and the turbulent regime structure were investigated. A V Nedospasov and S S Sobolev, Zh Tekh Fiz, 36 (IO), Ott 1966, 1758-l 767 (in Russian)
. 18
decay of discharge plasma with oscillating electrons in a strong magnetic field. (USSR) Presumably the causes of the anomalous quick decay of discharge plasma in a magnetic field with intensity higher than 10%Oe are the macroscopic turbulence and hf oscillation of plasma. The magnetic field critical values as a function of the pressure in the lOmato 10-l torr range are given. V G Grigorenko, Zh Tekh Fiz, 36 (lo), Ott 1966, 1800-1807 (in 294. Anomalous
Russian). 295. Ions mobility in own gas.
18 (USSR)
Equations for ion drift velocity in own gas are derived and calculated values are compared with those measured by other authors. B M Smimov, Zh Tekh Fiz, 36 (IO), Ott 1966,1864-1871 (in Russian). 18 : 31 2%. Influence of electrode material on the delay tbne of discharge at electrical breakdown in a vacuum gap. (USSR) An equation for the breakdown delay time is established. Satisfactory
calculations of these values are obtained for vacuum gaps wider than .02 inches, for narrower gaps the calculation may be used as a rough approximation. The influence of the residual gas pressure was not investigated. G M Kasslrov, Zh Tekh Fiz, 36 (IO), Ott 1966, 1883-1885 (in
301. Investigation of transmission secondary-electron emitters.
18 :30
(USSR) The preparation of transmission secondary-electron emitters is described. These consist of an A&O, grid or thin layer as a backing, Al intermediate layer and one or more secondary-emission layers of vacuum evaporated MgO or KCl. The best results were obtained with the porous KC1 layer of thickness 24 pm as an emitter (gain about 35 at 7 kV and at backing layer transparency 70 per cent). T Reichel and V Jares. Radiotekh Elektron. 11 (IO). Ott 1966. 18321836 (in Russian). 18 302. Charged particle flow to the cathode in a Penning type discharge. (USSR)
The direction and energy of the ions deposited on the centre of the cathode as a function of the magnetic field intensity, anode voltage and the pressure in the 1O-5 to 10d4 torr range were measured. GV Smirnitskaya and R. P Babertsyan, Radiotekh Elektron, 11 (IO), Ott 1966, 1897-1899
(in Russian).
18 volt-ampere characteristics of the leakage and emission current of sandwich cathodes. (Czechoslovakia) The influence of the thickness of the dielectric on the electrical properties of cathodes was investigated. Two different dielectrics (oxide and evaporated layers) were used, but no great difference was observed. V Balas, Czech J Phys, section B, 16 (7)) 1966, 569-577 (in English). 303. The
18
304. Ultrahigh vacuum apparatus for investigating film emission from a low-pressure mercury arc. (Germany)
The problems of pumping, wall materials and pressure measurement in ultrahigh vacuum apparatus (lo-’ to lo-@ torr) are discussed. The apparatus would be equally suitable for studying other problems of gas discharge physics. J Mitterauer, Elektrotech Maschinenbau, 83 (5), 1966, 308-311 (in German).
Russian). 18 297. Properties of a microwave discharge near plasma resonance. (USSR) The rapid increase of the 4713 A line intensity in a He discharge at
3 kMc was investigated. This effect is caused by changing the helium plasma resonance frequency at higher absorbed powers. A I Maksimov. Zh Tekh Fiz. 36 (IO). Ott 1966. 1894-1896 fin .., Russian).
18
298. Investigation of the speed of plasma extension at current break in
vacuum. (USSR) The speed of the plasma extension in a vacuum switch after breaking the dc current (30 to 1,000 A) was investigated. The speed of the plasma front is about 5 times higher than the speed of plasma during subsequent plasma arcing. MA Tyulina,Zh Tekh Fiz, 36 (IO), Ott 1966,1095-1908 (in Russian). 18 299. Excitation by Znd-ordercollisions in the radiation of N, and CO molecular hands from N,+ Ar, CO+ Ar mixtures in a glow discharge. (USSR) Mixtures argon and N, or CO with total pressures of 2 torr and N, or CO partial pressures of 0.02 to 1.98 torr, were prepared and subjected to a glow discharge. The influence of molecular bands corresponding to Znd-order collision excitation for the given partial pressures of N, and CO were determined and compared to calculated values. L A Chemenko, Zzv VUZ Fit, 9 (5)) 1966, 67-70 (in Russian). 18 300. Effect of crystal lattice thermal vibrations on ion-electron emission coe5cient. (USSR) The influence of temperature of Cu backing and of the angle of inci-
dence of bombarding ions on the ion-electron emission coefficient was investigated. Backings of Cu polycrystal and (110) and (111) faces of Cu single crystal were employed at temperatures 200 and 900°C bombarded by Ne, Ar and Kr ions with energies 30 keV. The effect of temperature was observed only on single crystal backings. I N Evdokimov et al, Fir Tverd Tela, 8 (ZO), Ott 1966, 2939-2944 (in Russian).
II. Vacuum apparatus and auxiliaries 20. Pumping
systems
20 305. The vacuum system of the MM II experiment. The MM II experimental assembly at Fontenay-aux-Roses was pumped down by a combination of oil diffusion pumps and titanium evaporation pumps on cold surfaces. New and larger equipment is being installed, aimed at providing a total pumping speed in excess of 106 litres/second. This vacuum system, the previous one, associated technical problems and some results of measurements are described. 2 Sledziewski and F Prevot, Euratom Information, 4 (IO), 1966, 1107, Rept (MF)
EUR 31OOe.
20 306. Vacuum furnace for high temperature fractural studies. (USA) An inexpensive vacuum furnace was constructed to study the high
temperature fracture of ceramic materials and was designed for use with an Instron testing machine. The vacuum chamber used is described and diagrams given. P L Gutshall and G D Swanson, Rev Sci Znstrum, 37,1966,1413-I414. 307. High vacuum aggregate HVAO-6/30/11.
20 (Germany)
The unit assembly described consists of a high vacuum oil diffusion pump with oil-vapour trap, programme valve, backing vacuum container and a magnetic backing pump valve. The pumping capacity is better than 30 litres/sec at lo-* torr. The pump is of the all-metal, three-stage fractionating type using oils with vapour pressure less than lo-’ torr at 25°C. Construction and operation of the various components are summarized. E Wagner and G Osterland, Jena Review, No 3, 1966, 185-186 (in English). 308. Laboratory vacuum furnace with exchange heating system. (Czechoslovakia)
20
Design details of a simple furnace, for vacuum annealing of Fe and other applications at lo-” torr in a chamber of volume 15 litres, are 111
abstracts
280-292 16 of gases on metals by the Auger process.
280. Study of the adsorption (USA)
The apparatus under construction to measure the degree of surface coverage using the Auger process is described. It will use an electron impact helium ion source, leading to a cylindrical lens which focuses the ions onto the target. The target is a single crystal tungsten ribbon mounted on two heating leads which pass directly into a liquid nitrogen cooling bath. A schematic of the adsorption-desorption experiment is included and the experimental technique is illustrated. D Alpert, Rep NASA-CR-75681; (Illinois Univ Urbana, Coordinated
18. Gaseous
R-286; AD-632596; Science Lab).
April
18 It is concluded that there are at least sixteen variables affecting breakdown in vacuum. Traditional methods of experimenting by varying one parameter at a time would take years to amass the data on which a cohesive theory could be formulated. A pilot experiment was set up based on the statistical approach to experimental design to evaluate the relative importance of each of the variables. The pilot experiment is a partial replica of a two-level full factorial design. It is expected that sufficient information will be collected to permit the elimination of variables having minor effects and to permit a more comprehensive design for the final experiment. Jan 1966 (Army
18 in potassium
and mercury.
(USA)
The resistivity of superheated potassium and mercury vapour was measured. Substantial heating of the gas by the discharge was avoided by flowing the gas through the discharge region. The resistivity of potassium gas at 7.8 Torr pressure, 870°K and 1 A/cm2 is 2.2 ohm cm. The resistivity of mercury gas at 14 Torr, 870°K and 0.67 A/cm2 is 10 ohm cm. The resistance was primarily due to short range electron/neutral atom collisions. The cross section for this process as calculated from the resistivity is 1.5 x lo-” cm” for potassium and 2.5 X 1O~l’ cm* for mercury. C A Guderjahn, Rep AId5-120; AFORS-65-1914; A 0628187, Jul_v I965 (Atomics
International,
Canoga Park, Cal(f). 18
283. Investigation An experimental
of high power gaseous electronics.
(USA)
technique is described for obtaining reproducible clean-up measurements in high power microwave duplexer discharges under controlled conditions. A basic clean-up rate is defined as the number of molecules sorbed per cm3 of discharge/square root of average incident power. Data is given for the clean-up of inert gases in quartz; hydrogen in 7070 glass, quartz, copper, nickel, molybdenum and kovar; and oxygen and bromine in kovar. It was found that life time of duplexers increases with the square of the ratio of gas volume to discharge area and with the square of the pressure range over which a tube remains operable. Life time is also inversely proportional to peak power and to the square of the duty cycle. H S Maddix, Rep AD-629537, Burlington, Mass). 284. A high resolution research. (USA)
Feb 1966 (Microwave
secondary
emission
Associates
spectrometer
Znc
18 : 39 for surface
The possibility of using secondary emission in surface research and the apparatus developed for this research are discussed. The secondary electrons were divided into two groups: primary electrons scattered (elastically or inelastically) from the surface, and electrons excited from the surface by the primaries. It is suggested that the following main areas can be investigated using the elastically scattered electrons: (1) the excitation of the vibrational states of adsorbed gas species on the surface; (2) the electronic transitions of the adsorbed atoms on surfaces; (3) the plasmon excitation by electron impact. Details of the apparatus constructed for high resolution studies are given and schematic diagrams are included. The operation of the monochromator/analyzer system is described and the operating characteristics are shown. Measurements obtained on the (100) surface of a tungsten single crystal ribbon are discussed and the energy distribution of secondary electrons from a contaminated 110
Univ Urbana, Coordinated
Science Lab).
18 285. High frequency discharge in a ring electrode. (USSR) The mechanism of the plasma configuration excitation by a ring electrode hf field was investigated at pressures of 2 x 10m2to 1 torr. A D Andreev et al, Zh Tekh Fiz, 36 (9), Russian).
Sept 1966, 1636-1638
(in
18 regions of the
286. Energy and angle distribution of ions in various cathode in a higb voltage Penning discharge. (USSR)
281. Design of a high voltage breakdown in vacuum experiment. (USA)
282. Flowing gas discharges
(Illinois
1966.
electronics
M N Cbrepta et al, Rep ECOM-2655; AD-628042, Electronics Labs, Fort Monmouth, NJ).
surface, from the surface after exposure to nitrogen and hydrogen and from clean tungsten, are presented. D Alpert, Rep NASA-CR-75681; R-286; AD632596; April 1966
The properties of the Penning discharge were studied with particular reference to the pumping action. It was found that residual gas ions bombard only a narrow area at the cathode centre in the direction perpendicualr to the cathode surface with energies dependent on the pressure. Experiments were performed at the 1O-4 to 1O-Btorr range. 0 K Kurbatov, Zh Tekh Fiz, 36 (9)) Sept 1966,1665-1668 (in Russian). 287. Atomic beam Ionizer as a source of polarized ions.
18 :33 (USSR)
The design of the Zinchenko type hydrogen ionizer with high efficiency (about 4.5 x lo-*) is described. It operates at 1O-8 torr with an oxide cathode as the electron source and hydrogen atom beam intensity is measured by an ionization gauge. 0 I Ekhichev et al, Zh Tekh Fiz, 36 (9), Sept 1966, 1681-1684 (in Russian). 288. Two mechanisms crystals. (USSR)
of photo-stimulated
electron
emission
18 by ion
It is shown that the photo-thermal mechanism of the photo-stimulated electron emission from F-centres of ion crystals is well established only when ion crystals are in a gas atmosphere and that the photoionization mechanism exists alone under high vacuum conditions. A N Belkind et al, Izv Akad Nauk SSSR, Ser Fiz 30 (9), Sept 1966, 1448-1450
(in Russian).
18 :30 289. The effect of backing material on photo-emf in CdTe films. (USSR)
It is known that photo-emf of CdTe thin films depends on the backing material and its temperature during vacuum condensation of the films. Experiments showed that, for AlBOS backing, the CdTe photo-emf more than double that for glass backing. The backing temperature dependence is described. L S Palatnik and V K Sorokin, Fiz Tverd Tela, 8 (9), Sept 1966,27952796 (in Russian). 18 290. Dependence of secondary electron emission and electron elastic reflection on thickness of barium oxide film on tungsten in the case of low energy primary electrons. (USSR)
For primary electrons with energies 3 to 50 eV the depth of secondary electron emission is 16 monolayers and it is not dependent on the primary electron energy. Electron elastic reflection depth is about 5 monolayers and it is not dependent on the primary electron energies in the range 5 to 17 eV. All experiments were made at IO+ torr and carefully baked polycrystal- tungsten was employed as the backing for BaO layers. A R Shul’man and N P Bazhanova, 2797-2798 (in Russian).
Fiz Tverd Tela, 8 (9), Sept. I966
18 :33 291. Measurement of cathode oxide coating electroconductivity and the coating work functions, using a probe. (USSR) Work function of the cathode oxide coatings was found by measuring the electroconductivity of the oxides and its changes in a magnetic field. Advantages of the described method are: the temperature of the probe and the oxide are identical; and the probe position determinations have only slight influence on experimental error. Typical characteristics are given and compared with those obtained by Schottky method. E M Sher, Radiotekh Elektron, 11 (9), Sept 1966, 1721-1723 (in Russian). 18 292. Secondary electron emission of alloys of zirconium and hafnimn with rhenium. (USSR) The influence of the composition of Zr-Re and Hf-Re alloys on the
Classified
abstracts
293-308
secondary electron emission, the primary electron non-elastic reflection and the secondary electrons energy distribution, was studied. L A Ermolaev and B Kh Dvubua. Radiotekh Elektron. , 11 (91. ,,, Scot . 1966, 1724-1728
(in Russian>.
’
18 293. Positive column of helium discharge in a strong magnetic field. (USSR)
The transformation of a He discharge positive column from a laminar convection regime into a turbulent one and the turbulent regime structure were investigated. A V Nedospasov and S S Sobolev, Zh Tekh Fiz, 36 (IO), Ott 1966, 1758-l 767 (in Russian)
. 18
decay of discharge plasma with oscillating electrons in a strong magnetic field. (USSR) Presumably the causes of the anomalous quick decay of discharge plasma in a magnetic field with intensity higher than 10%Oe are the macroscopic turbulence and hf oscillation of plasma. The magnetic field critical values as a function of the pressure in the lOmato 10-l torr range are given. V G Grigorenko, Zh Tekh Fiz, 36 (lo), Ott 1966, 1800-1807 (in 294. Anomalous
Russian). 295. Ions mobility in own gas.
18 (USSR)
Equations for ion drift velocity in own gas are derived and calculated values are compared with those measured by other authors. B M Smimov, Zh Tekh Fiz, 36 (IO), Ott 1966,1864-1871 (in Russian). 18 : 31 2%. Influence of electrode material on the delay tbne of discharge at electrical breakdown in a vacuum gap. (USSR) An equation for the breakdown delay time is established. Satisfactory
calculations of these values are obtained for vacuum gaps wider than .02 inches, for narrower gaps the calculation may be used as a rough approximation. The influence of the residual gas pressure was not investigated. G M Kasslrov, Zh Tekh Fiz, 36 (IO), Ott 1966, 1883-1885 (in
301. Investigation of transmission secondary-electron emitters.
18 :30
(USSR) The preparation of transmission secondary-electron emitters is described. These consist of an A&O, grid or thin layer as a backing, Al intermediate layer and one or more secondary-emission layers of vacuum evaporated MgO or KCl. The best results were obtained with the porous KC1 layer of thickness 24 pm as an emitter (gain about 35 at 7 kV and at backing layer transparency 70 per cent). T Reichel and V Jares. Radiotekh Elektron. 11 (IO). Ott 1966. 18321836 (in Russian). 18 302. Charged particle flow to the cathode in a Penning type discharge. (USSR)
The direction and energy of the ions deposited on the centre of the cathode as a function of the magnetic field intensity, anode voltage and the pressure in the 1O-5 to 10d4 torr range were measured. GV Smirnitskaya and R. P Babertsyan, Radiotekh Elektron, 11 (IO), Ott 1966, 1897-1899
(in Russian).
18 volt-ampere characteristics of the leakage and emission current of sandwich cathodes. (Czechoslovakia) The influence of the thickness of the dielectric on the electrical properties of cathodes was investigated. Two different dielectrics (oxide and evaporated layers) were used, but no great difference was observed. V Balas, Czech J Phys, section B, 16 (7)) 1966, 569-577 (in English). 303. The
18
304. Ultrahigh vacuum apparatus for investigating film emission from a low-pressure mercury arc. (Germany)
The problems of pumping, wall materials and pressure measurement in ultrahigh vacuum apparatus (lo-’ to lo-@ torr) are discussed. The apparatus would be equally suitable for studying other problems of gas discharge physics. J Mitterauer, Elektrotech Maschinenbau, 83 (5), 1966, 308-311 (in German).
Russian). 18 297. Properties of a microwave discharge near plasma resonance. (USSR) The rapid increase of the 4713 A line intensity in a He discharge at
3 kMc was investigated. This effect is caused by changing the helium plasma resonance frequency at higher absorbed powers. A I Maksimov. Zh Tekh Fiz. 36 (IO). Ott 1966. 1894-1896 fin .., Russian).
18
298. Investigation of the speed of plasma extension at current break in
vacuum. (USSR) The speed of the plasma extension in a vacuum switch after breaking the dc current (30 to 1,000 A) was investigated. The speed of the plasma front is about 5 times higher than the speed of plasma during subsequent plasma arcing. MA Tyulina,Zh Tekh Fiz, 36 (IO), Ott 1966,1095-1908 (in Russian). 18 299. Excitation by Znd-ordercollisions in the radiation of N, and CO molecular hands from N,+ Ar, CO+ Ar mixtures in a glow discharge. (USSR) Mixtures argon and N, or CO with total pressures of 2 torr and N, or CO partial pressures of 0.02 to 1.98 torr, were prepared and subjected to a glow discharge. The influence of molecular bands corresponding to Znd-order collision excitation for the given partial pressures of N, and CO were determined and compared to calculated values. L A Chemenko, Zzv VUZ Fit, 9 (5)) 1966, 67-70 (in Russian). 18 300. Effect of crystal lattice thermal vibrations on ion-electron emission coe5cient. (USSR) The influence of temperature of Cu backing and of the angle of inci-
dence of bombarding ions on the ion-electron emission coefficient was investigated. Backings of Cu polycrystal and (110) and (111) faces of Cu single crystal were employed at temperatures 200 and 900°C bombarded by Ne, Ar and Kr ions with energies 30 keV. The effect of temperature was observed only on single crystal backings. I N Evdokimov et al, Fir Tverd Tela, 8 (ZO), Ott 1966, 2939-2944 (in Russian).
II. Vacuum apparatus and auxiliaries 20. Pumping
systems
20 305. The vacuum system of the MM II experiment. The MM II experimental assembly at Fontenay-aux-Roses was pumped down by a combination of oil diffusion pumps and titanium evaporation pumps on cold surfaces. New and larger equipment is being installed, aimed at providing a total pumping speed in excess of 106 litres/second. This vacuum system, the previous one, associated technical problems and some results of measurements are described. 2 Sledziewski and F Prevot, Euratom Information, 4 (IO), 1966, 1107, Rept (MF)
EUR 31OOe.
20 306. Vacuum furnace for high temperature fractural studies. (USA) An inexpensive vacuum furnace was constructed to study the high
temperature fracture of ceramic materials and was designed for use with an Instron testing machine. The vacuum chamber used is described and diagrams given. P L Gutshall and G D Swanson, Rev Sci Znstrum, 37,1966,1413-I414. 307. High vacuum aggregate HVAO-6/30/11.
20 (Germany)
The unit assembly described consists of a high vacuum oil diffusion pump with oil-vapour trap, programme valve, backing vacuum container and a magnetic backing pump valve. The pumping capacity is better than 30 litres/sec at lo-* torr. The pump is of the all-metal, three-stage fractionating type using oils with vapour pressure less than lo-’ torr at 25°C. Construction and operation of the various components are summarized. E Wagner and G Osterland, Jena Review, No 3, 1966, 185-186 (in English). 308. Laboratory vacuum furnace with exchange heating system. (Czechoslovakia)
20
Design details of a simple furnace, for vacuum annealing of Fe and other applications at lo-” torr in a chamber of volume 15 litres, are 111