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Influence of platinum group metal films on oxide cathode emission
C l a s s i f i e d a b s t r a c t s 714-726 16 714. Adsorption, degassing and solution equilibrium in the nitrogenniobium system under ultrahigh vacuum and at high temperature. (USA) R A P a s t e r n a k et al, J t'lectrochem Soc, 113, 1966, 731 -735.
18. G A S E O U S E L E C r R O N I C S 18:16 Investigation of adsorption of caesium on tungsten single crystals. See abstract n u m b e r 712. 18 715. Energy distribution of electrons in the positive column of an argon discharge. ( U S S R ) Energy distribution of electrons in the positive c o l u m n of discharges with currents o f 1130 a n d 300 m A in A r at pressures o f 3 x 10 -~ to 4.5 torr was m e a s u r e d . At lower pressures this distribution resembles Maxwell distribution, but for pressures above 3 torr s o m e a n o m a lies were found. Yu M Kagan et al, Zh Tekh Fiz, 36 (12), Dec 1966, 2219-2220 (#:
Russian). 18 716. Triggering electrical breakdown at high vacuum by means of a thermal pulse. (USSR) Electrical b r e a k d o w n at high v a c u u m was initiated by pulse heating o f a third additional electrode. It is s h o w n that the only initiating m e c h a n i s m o f the brcakdov, n is pulse dcsorption from the heated electrode a n d relations between the delay time o f the breakdo',~n arcing a n d the heating energy ~ere determined. Possibilities of calculating these values are discussed. This m e t h o d is suitable for s o m e high v a c u u m b r e a k d o w n investigations as only one initiating m e c h a n i s m is applied. L V Tarasova and V G Kaliuiu, Zh Tekh Fiz, 36 (12), Dec 1966, 21482153 (hi Russian). 17 717. Dissociation of CD~ ", CI-t~~ and CD~- after collisions with neon atoms and air molecules. ( U S S R ) C D v , C H s ~ a n d CD4- ions dissociation in mixtures o f air a n d Ne at pressures of 10 -4 to 10 -s torr was investigated using a doublefocusing mass-spectrometer. S E Kupriyanov, Zh Tekh Fiz, 36 (12), Dec 1966, 2161 2163 (h:
Russian). 18 718. Versatile injector of hydrogen isotope negative ions. (USSR) T h e injector consists o f an h f source o f positive h y d r o g e n isotope a n d a source o f ultrasonic m e r c u r y stream which overcharges the positive ions. B e a m s o f negative ions o f intensities 25/~A for H~-, 16 p A for D~- a n d 1 2 / , A for T~- were obtained. M a s s spectra o f the b e a m s are also given. Yu M Kbirnyi and L N Kochemasova, Pribory Tekh Ek~7)er, 11 (6), Nov-Dec 1966, 32-36 (h: Russian). 18 719. Compact duoplasmatron type negative ion source. (USSR) A design o f the d u o p l a s m a t r o n type negative ion source is described. T h e speciality of this design is the use of a ceramic p e r m a n e n t m a g n e t as an high voltage insulator in v a c u u m . Beams of H t - up to 140/~A were obtained. A V Almazov et al, Pribory Tekh Eksper, 11 (6), Nov-Dec 1966, 36-39
(in Russian). 18 720. Device for thin dielectric films on metals surfaces diagnostics. (USSR) A device m e a s u r i n g post-discharge electron emission from metal surfaces is described. This emission occurs only in the presence o f thin dielectric layers, eg oxides, a n d the m e t h o d is therefore suitable for growth evaluations on this type o f film. T h e emission current from clean surfaces is below 10 ~ A, while from a M o surface after 15 m i n u t e s exposure to air a t m o s p h e r e the emission, at 10 sec after breaking the discharge, is 2 × 10 ~7 A. A n o t h e r application o f this m e t h o d is the evaluation o f surface cleaning processes. For example, it is s h o w n that baking M o samples to 750'C at 5 × 10 -r' torr is not sufficient to clean the surface. N V Tatarinova and P N Cbistyakov, Pribory Tekh Eksper, 11 (6), Nov- Dec" 1966, 137-140 (in Russian). 244
18 -33 721. Influence of the residual gas partial pressures on the operation of type U E M V - 1 0 0 electron gun. (USSR) The influence of tile nature and pressure of residual ga,~ on the discharge initiation in an electron microscope type UEMV-IO0 electron g u n was investigated. It was t \ m n d that the critical pressure for air atrnosphere is 8.3 × 10 -3 torr, for Kr, 5 × 10 ~ tort, for [t.., 3 x 10 -~ torr and for He 4 . 5 x 10 -z tort in the voltage region o f 50 150 kV. The influence o f the h y d r o c a r b o n layers at electrodes on the discharge initiating voltage is briefly discussed. !' A Stoyanov et al, Pribory Tekh Eksper, I1 (6), N o v - D e c 1966, 202 203 (in Russian). 18 722. Secondary electron emission of scandium. (USSR) Secondary electron emission coefficient o f 0.83 for primary electron energy of 250 cV a n d non-elastic reflection coefficient o f 0.27 o f v a c u u m melted s c a n d i u m ',,,ere m e a s u r e d in an electron microscope for primary electron energies o f 100-2,000 eV a n d backing temperature of a b o u t 1,000 ~K. T h e m a x i m u m probable secondary electron energy was f o u n d to be 4 eV. L A Ermolaev and A A Gugnin, Radiotekh Elektron, 11 (12), Dec 1966, 2257-2258 (in Russian). 18 723. Some special features of transmission secondary electron emission depending upon the field. (USSR) T r a n s m i s s i o n secondary electron emission of porous p o t a s s i u m c h l o r i d c e v a p o r a t e d o n a l u m i n i u m in an argon a t m o s p h e r e , w a s investigated a n d the following a n o m a l y found: the secondary emission coefficient reaches tv, o m a x i m a , the lower one at a b o u t 800 eV a n d the higher at about 3.5 eV. This coefficient increases sharply above a field intensity o f 40 V for the first m a x i m u m primary electrons, but for primary electrons with energies near to the second m a x i m u m , the values o f this coefficient are practically c o n s t a n t above 30 V. After long-term electron b o m b a r d m e n t of the p o t a s s i u m chloride tihn, the values of the secondary emission coefficient are significantly lower. N L Yasnopolskiy et al, Radiotekh Elektron, I 1 (12), Dec 1966. 2259-2260 (in Russian) 18:33 724. Influence of platinum group metal films on oxide cathode emission. (USSR) To form elc'ctron beams the cathodes in which the emitting area is clearly defined are required. Results o f investigations on m a s k i n g the oxide c a t h o d e by Pt, lr or Os, are presented. F o r this application Pt is not the suitable material, but an Ir thin film on the oxide c a t h o d e coating reduces emission a b o u t 300 times without influencing the emission from u n m a s k e d cathode areas. It also speeds up the activation o f the cathode. Properties of the m a s k e d c a t h o d e v, ere stable t h r o u g h o u t 1,800 operational hours. Similar properties were found using o s m i u m . Yu A Volodin et al, Radiotekh Elektron, 11 (12), Dec" 1966, 2262-2265
(in Russian). 18 725. Arc initiation at metal surfaces in a hydrogen Penning discharge. (Great Britain) Arc f o r m a t i o n at metal surfaces in a hydrogen plasma has been studied at gas pressure of 25 to 60 millitorr. Plasma generation was by m e a n s o f a high current, cold cathode, Penning-type discharge with an axial magnetic field, which defined the electrode areas receiving the ion b o m b a r d m e n t , Planar cathodes a n d probe wires o f various metals were subjected to 100/tscc and 50 psec pulses respectively each at a b o u t 10 A/cm" a n d 2 kV. T h e occurrence o f arcs ~.as investigated over long periods o f up to 10 ~ pulses at a rate o f one per sec. J H Holliday and G G Isaacs, BritJ ApplPhys, 17, 1966, 1575-1583. 18 726. Barium vapour activation of oxide cathodes. (USA) Experimental results are presented for (BaSr)O cathodes exposed to a heated Ba-covercd surface. These results indicate that there is a maxim u m in the steady state level o f pulsed thermionic emission as a function o f increasing Ba source temperatures, when the oxide is at a m u c h higher temperature. T h e v a c u u m tube structure used in this study is shown. R H Springer and D E Anderson, J .4ppl Phys, 37, 1966, 4330-4340.
18. G A S E O U S E L E C r R O N I C S 18:16 Investigation of adsorption of caesium on tungsten single crystals. See abstract n u m b e r 712. 18 715. Energy distribution of electrons in the positive column of an argon discharge. ( U S S R ) Energy distribution of electrons in the positive c o l u m n of discharges with currents o f 1130 a n d 300 m A in A r at pressures o f 3 x 10 -~ to 4.5 torr was m e a s u r e d . At lower pressures this distribution resembles Maxwell distribution, but for pressures above 3 torr s o m e a n o m a lies were found. Yu M Kagan et al, Zh Tekh Fiz, 36 (12), Dec 1966, 2219-2220 (#:
Russian). 18 716. Triggering electrical breakdown at high vacuum by means of a thermal pulse. (USSR) Electrical b r e a k d o w n at high v a c u u m was initiated by pulse heating o f a third additional electrode. It is s h o w n that the only initiating m e c h a n i s m o f the brcakdov, n is pulse dcsorption from the heated electrode a n d relations between the delay time o f the breakdo',~n arcing a n d the heating energy ~ere determined. Possibilities of calculating these values are discussed. This m e t h o d is suitable for s o m e high v a c u u m b r e a k d o w n investigations as only one initiating m e c h a n i s m is applied. L V Tarasova and V G Kaliuiu, Zh Tekh Fiz, 36 (12), Dec 1966, 21482153 (hi Russian). 17 717. Dissociation of CD~ ", CI-t~~ and CD~- after collisions with neon atoms and air molecules. ( U S S R ) C D v , C H s ~ a n d CD4- ions dissociation in mixtures o f air a n d Ne at pressures of 10 -4 to 10 -s torr was investigated using a doublefocusing mass-spectrometer. S E Kupriyanov, Zh Tekh Fiz, 36 (12), Dec 1966, 2161 2163 (h:
Russian). 18 718. Versatile injector of hydrogen isotope negative ions. (USSR) T h e injector consists o f an h f source o f positive h y d r o g e n isotope a n d a source o f ultrasonic m e r c u r y stream which overcharges the positive ions. B e a m s o f negative ions o f intensities 25/~A for H~-, 16 p A for D~- a n d 1 2 / , A for T~- were obtained. M a s s spectra o f the b e a m s are also given. Yu M Kbirnyi and L N Kochemasova, Pribory Tekh Ek~7)er, 11 (6), Nov-Dec 1966, 32-36 (h: Russian). 18 719. Compact duoplasmatron type negative ion source. (USSR) A design o f the d u o p l a s m a t r o n type negative ion source is described. T h e speciality of this design is the use of a ceramic p e r m a n e n t m a g n e t as an high voltage insulator in v a c u u m . Beams of H t - up to 140/~A were obtained. A V Almazov et al, Pribory Tekh Eksper, 11 (6), Nov-Dec 1966, 36-39
(in Russian). 18 720. Device for thin dielectric films on metals surfaces diagnostics. (USSR) A device m e a s u r i n g post-discharge electron emission from metal surfaces is described. This emission occurs only in the presence o f thin dielectric layers, eg oxides, a n d the m e t h o d is therefore suitable for growth evaluations on this type o f film. T h e emission current from clean surfaces is below 10 ~ A, while from a M o surface after 15 m i n u t e s exposure to air a t m o s p h e r e the emission, at 10 sec after breaking the discharge, is 2 × 10 ~7 A. A n o t h e r application o f this m e t h o d is the evaluation o f surface cleaning processes. For example, it is s h o w n that baking M o samples to 750'C at 5 × 10 -r' torr is not sufficient to clean the surface. N V Tatarinova and P N Cbistyakov, Pribory Tekh Eksper, 11 (6), Nov- Dec" 1966, 137-140 (in Russian). 244
18 -33 721. Influence of the residual gas partial pressures on the operation of type U E M V - 1 0 0 electron gun. (USSR) The influence of tile nature and pressure of residual ga,~ on the discharge initiation in an electron microscope type UEMV-IO0 electron g u n was investigated. It was t \ m n d that the critical pressure for air atrnosphere is 8.3 × 10 -3 torr, for Kr, 5 × 10 ~ tort, for [t.., 3 x 10 -~ torr and for He 4 . 5 x 10 -z tort in the voltage region o f 50 150 kV. The influence o f the h y d r o c a r b o n layers at electrodes on the discharge initiating voltage is briefly discussed. !' A Stoyanov et al, Pribory Tekh Eksper, I1 (6), N o v - D e c 1966, 202 203 (in Russian). 18 722. Secondary electron emission of scandium. (USSR) Secondary electron emission coefficient o f 0.83 for primary electron energy of 250 cV a n d non-elastic reflection coefficient o f 0.27 o f v a c u u m melted s c a n d i u m ',,,ere m e a s u r e d in an electron microscope for primary electron energies o f 100-2,000 eV a n d backing temperature of a b o u t 1,000 ~K. T h e m a x i m u m probable secondary electron energy was f o u n d to be 4 eV. L A Ermolaev and A A Gugnin, Radiotekh Elektron, 11 (12), Dec 1966, 2257-2258 (in Russian). 18 723. Some special features of transmission secondary electron emission depending upon the field. (USSR) T r a n s m i s s i o n secondary electron emission of porous p o t a s s i u m c h l o r i d c e v a p o r a t e d o n a l u m i n i u m in an argon a t m o s p h e r e , w a s investigated a n d the following a n o m a l y found: the secondary emission coefficient reaches tv, o m a x i m a , the lower one at a b o u t 800 eV a n d the higher at about 3.5 eV. This coefficient increases sharply above a field intensity o f 40 V for the first m a x i m u m primary electrons, but for primary electrons with energies near to the second m a x i m u m , the values o f this coefficient are practically c o n s t a n t above 30 V. After long-term electron b o m b a r d m e n t of the p o t a s s i u m chloride tihn, the values of the secondary emission coefficient are significantly lower. N L Yasnopolskiy et al, Radiotekh Elektron, I 1 (12), Dec 1966. 2259-2260 (in Russian) 18:33 724. Influence of platinum group metal films on oxide cathode emission. (USSR) To form elc'ctron beams the cathodes in which the emitting area is clearly defined are required. Results o f investigations on m a s k i n g the oxide c a t h o d e by Pt, lr or Os, are presented. F o r this application Pt is not the suitable material, but an Ir thin film on the oxide c a t h o d e coating reduces emission a b o u t 300 times without influencing the emission from u n m a s k e d cathode areas. It also speeds up the activation o f the cathode. Properties of the m a s k e d c a t h o d e v, ere stable t h r o u g h o u t 1,800 operational hours. Similar properties were found using o s m i u m . Yu A Volodin et al, Radiotekh Elektron, 11 (12), Dec" 1966, 2262-2265
(in Russian). 18 725. Arc initiation at metal surfaces in a hydrogen Penning discharge. (Great Britain) Arc f o r m a t i o n at metal surfaces in a hydrogen plasma has been studied at gas pressure of 25 to 60 millitorr. Plasma generation was by m e a n s o f a high current, cold cathode, Penning-type discharge with an axial magnetic field, which defined the electrode areas receiving the ion b o m b a r d m e n t , Planar cathodes a n d probe wires o f various metals were subjected to 100/tscc and 50 psec pulses respectively each at a b o u t 10 A/cm" a n d 2 kV. T h e occurrence o f arcs ~.as investigated over long periods o f up to 10 ~ pulses at a rate o f one per sec. J H Holliday and G G Isaacs, BritJ ApplPhys, 17, 1966, 1575-1583. 18 726. Barium vapour activation of oxide cathodes. (USA) Experimental results are presented for (BaSr)O cathodes exposed to a heated Ba-covercd surface. These results indicate that there is a maxim u m in the steady state level o f pulsed thermionic emission as a function o f increasing Ba source temperatures, when the oxide is at a m u c h higher temperature. T h e v a c u u m tube structure used in this study is shown. R H Springer and D E Anderson, J .4ppl Phys, 37, 1966, 4330-4340.