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429. Energy spectra of electrons released in collisions between fast alkali metal atoms and helium and neon atoms
Classified
abstracts
419-430
electron bombardment was investigated in high and ultrahigh vacuum. P-n junctions and induced conductivity were esamined. It is shown that the number of generated pairs depends linearly on the primary electron energy. The influence of the surface potential barrier on the pair generation is dcmonstratcd. I A Abrosan and L A Tsekhnovicher. Fi: TIW~/ T&. 11 ( I I ). h’or 1969.
3368-3369
(in Russinn). I6
419. Structural influences on adsorbate binding energy. I. Carbon monoxide on (100) palladium. (USA) The structural arrangement and binding energy of CO adsorbed on a (100) surface of palladium have been dctcrmincd and rclatcd to each other over the submonolayer covcragc range. Thcrc arc four distinct equilibrium structural arrangements of CO: (I 1 At low coveragcs (<0.4 monolayers). there is a random lattice gas configuration. (2) Just below 0.5 monolayers a liquidlike short-range order arrangement is found. (3) At exactly 0.5 monolaycrs an ovcrlaycr structure forms that is in complete registry with the substrate. (4) For coveragcs greater than 0.5 monolayers, the overlayer structure is uniaxially compressed to form an overlayer which is out of registry with the palladium substrate. J C Tracy and P 1%’ Palmberg. J Chrn~ P/I.IT, 51 (I I), I Dee 1969,
4852-4862. 18. GASEOUS
ELECTRONICS
18 :37 Composition in vacuum.
of the vapour over See abstract number
lanthanum 503.
hesaboride
as it evaporates
18 420. Fabrication
processes appropriate to oxide cathodes for longpulse operation. (France) The various stages of oxide cathode formation are examined and the effect of variations in the environmental conditions on the formation, are discussed. Tt is shown that,‘with adequate care, cathodes may be obtained capable of satisfactory operations at a pulse-width of 2.5 microseconds at a duty ratio of 0.001. These cathodes operate at 800°C providing current densities of the order of 7A/em? under space charge limited conditions. Such cathodes are of particular value in magnetrons for which primary emission from the cathode is important. J L Bahri, Le Vitie, 24 (143). Se+OCI 1969, 375-278 fin Frerwh).
18 421. Problems of prebreakdown current measurement in 60 Hz vacuum breakdown studies. (Great Britain) A knowledge of the characteristics of prebreakdown currents in vacuum under power frequency ac excitation is invaluable to the designer of vacuum-insulated power apparatus. In this paper, the problems encountered while attempting to measure prebreakdown currents are enumerated and remedial measures are suggested by the authors. G D Theopbilus et al, Vucrtwn, 20 (I), Jurr 1970, I l-14.
18 422. On
the theory of low-voltage arcs in a thermionic energy converter. (USSR) The volt-ampere characteristics of thermionic energy converters in the arc operation are calculated on the basis of equations for ion and electron motion. The calculated and experimental data are compared. A A Belokon and E B Sonin, Z/I Tekh Fir, 39 (I I ), No IV 1969.2 105-2 I I 8
(in Russian). 18 423. Hollow
cathode
in the caesium low-voltage arc of a thermionic energy converter. (USSR) Application of a hollow cathode in the caesium low-voltage arc of a thermionic energy converter is investigated. It is found that the total current of the thermionic energy converter can be considerably augmented by an increase in the thermionic cathode surface. Voltampere and spectroscopic characteristics are measured for different caesium vapour pressures. It is concluded that the current increase due to the cathode surface enlargement is dependent on the plasma penetration in the cathode cavity. E P Busygin et al;Z/z Tckh Fiz, 39 (II), Nov 1969, 2119-2124 (01
Russian). I8 424. On Discharge Analysis
218
discharge formation in tubes. (USSR) formation in low pressure gas-filled tubes is of experimental data shows that the primary process
studied. has the
character of a one-electrode discharge propagated through the tube. The transition from one-electrode to glow discharge is connected with the change of the field in the cathode region and with generation of potential and ionization waves. L N Tunitskiy and E M Cherkasov, Z/I Tcklr Fi:. 39 (I 2). net 1969. 21 73-2176 (iu Rtrminrr). I8 425. Investigation of a limited discharge with a heated cathode in magnetic field. (USSR) Results arc presented of an experimental investigation of a discharge with a limited cross-section in helium prcssurc range of 5 IO n to 0.2 torr with heated tungsten cathode in magnetic feld. The transversal distribution of the plasma density is measured. It is shown that this transversal distribution is determined by charged particle diffusion. At pressures below 5 lo-’ torr a considerable disagrccmcnt between espsrimental data and calculated values is observed. 0 V Kozak and L L Masechnik, Z/r T&/I Fiz, 39 (12). Dec. 1969, 2 177-2182 (in Russinn). 18 426. Excitation and ionization processes in the plasma of a helium microwave discharge. (USSR) The relative and absolute intensities of spectral lines and the ionization frequency in a stationary helium microwave discharge arc determined. The experimental data are compared with calculated values and also with known values for the discharge column of a dc discharge. Electrons with high energy are found in the investigated type of discharge. At a helium pressure of 5 torr the electron energy distribution is close to Maxwellian. A I Maksimov, Z/I Tekh Fi:, 39 (I I ), No\! 1969, 1989-l 996 (iu Rwsimr). I8 427. Investigation of He’ ion motion in He in crossed electric and magnetic fields. (USSR) He+ ion drift in helium gas in the pressure range 10-?-3’. IO ~’ torr is experimentally investigated for the case of crossed electric and magnetic fields. The ion mobility is determined as a function of the gas pressure. L L Pasechnik and V V Yagola, Z/I Tekh Fiz, 39 (IZ), Dee 1969, 2198-2202 (i/r Russian). 18 428. Electron emission on phase transformation in SbSI. (USSR) Exo-electron emission at phase transformation in SbSI was measured with the aid of an electron counter. Maximum electron emission was observed at the temperature increase in the region of the phase transformation. Preliminary X-ray irradiation of SbSl considerably increases exo-electron emission at phase transformation. From this observation it is concluded that the exo-electron emission depends on structural defects. V V Kedabichus et al, Fiz Twrd Teh, 11 (12). Dee 1969, 3615-3617 (in
RmCnl).
I8 429. Energy spectra of electrons released in collisions between fast alkali metal atoms and helium and neon atoms. (USSR) The energy spectra of electrons liberated on ionization due to collisions between two neutral atoms are studied. The experimental vacuum system is described and results are presented for alkali metal atom energies of 200 to 3000 eV, colliding with He and Ne gas, at a pressure of 5 Y IO-’ torr. A retarding potential technique is used to determine the energy spectra of electrons moving perpendicularly to the direction of the primary atom beam. The experimental results are discussed. V I Ogurtsov and Yu F Bydin, Z/I Eksper Teor Fiz, 57 (6), Dee 1969, 1908-I 916 (in Russian). I8 ~37 430. Equilibrium thermodynamic analysis of the barium aluminatetungsten system. (USSR) Porous tungsten impregnated with barium aluminate is extensively used as an efficient thermionic emitter in vacuum and in low pressure devices. A thermodynamic analysis of the equilibrium pressure of barium accompanying the reactions due to interaction between barium aluminate and tungsten, is presented. The value obtained for the barium partial pressure is I Y IO-” torr, at the operating temperature of the impregnated cathode. G A Meerson et al, Izv Akad Nauk SSSR Neorg Muter, 5 (l2), Dee 1969, 2227-2229 (in R~rssiurr).
abstracts
419-430
electron bombardment was investigated in high and ultrahigh vacuum. P-n junctions and induced conductivity were esamined. It is shown that the number of generated pairs depends linearly on the primary electron energy. The influence of the surface potential barrier on the pair generation is dcmonstratcd. I A Abrosan and L A Tsekhnovicher. Fi: TIW~/ T&. 11 ( I I ). h’or 1969.
3368-3369
(in Russinn). I6
419. Structural influences on adsorbate binding energy. I. Carbon monoxide on (100) palladium. (USA) The structural arrangement and binding energy of CO adsorbed on a (100) surface of palladium have been dctcrmincd and rclatcd to each other over the submonolayer covcragc range. Thcrc arc four distinct equilibrium structural arrangements of CO: (I 1 At low coveragcs (<0.4 monolayers). there is a random lattice gas configuration. (2) Just below 0.5 monolayers a liquidlike short-range order arrangement is found. (3) At exactly 0.5 monolaycrs an ovcrlaycr structure forms that is in complete registry with the substrate. (4) For coveragcs greater than 0.5 monolayers, the overlayer structure is uniaxially compressed to form an overlayer which is out of registry with the palladium substrate. J C Tracy and P 1%’ Palmberg. J Chrn~ P/I.IT, 51 (I I), I Dee 1969,
4852-4862. 18. GASEOUS
ELECTRONICS
18 :37 Composition in vacuum.
of the vapour over See abstract number
lanthanum 503.
hesaboride
as it evaporates
18 420. Fabrication
processes appropriate to oxide cathodes for longpulse operation. (France) The various stages of oxide cathode formation are examined and the effect of variations in the environmental conditions on the formation, are discussed. Tt is shown that,‘with adequate care, cathodes may be obtained capable of satisfactory operations at a pulse-width of 2.5 microseconds at a duty ratio of 0.001. These cathodes operate at 800°C providing current densities of the order of 7A/em? under space charge limited conditions. Such cathodes are of particular value in magnetrons for which primary emission from the cathode is important. J L Bahri, Le Vitie, 24 (143). Se+OCI 1969, 375-278 fin Frerwh).
18 421. Problems of prebreakdown current measurement in 60 Hz vacuum breakdown studies. (Great Britain) A knowledge of the characteristics of prebreakdown currents in vacuum under power frequency ac excitation is invaluable to the designer of vacuum-insulated power apparatus. In this paper, the problems encountered while attempting to measure prebreakdown currents are enumerated and remedial measures are suggested by the authors. G D Theopbilus et al, Vucrtwn, 20 (I), Jurr 1970, I l-14.
18 422. On
the theory of low-voltage arcs in a thermionic energy converter. (USSR) The volt-ampere characteristics of thermionic energy converters in the arc operation are calculated on the basis of equations for ion and electron motion. The calculated and experimental data are compared. A A Belokon and E B Sonin, Z/I Tekh Fir, 39 (I I ), No IV 1969.2 105-2 I I 8
(in Russian). 18 423. Hollow
cathode
in the caesium low-voltage arc of a thermionic energy converter. (USSR) Application of a hollow cathode in the caesium low-voltage arc of a thermionic energy converter is investigated. It is found that the total current of the thermionic energy converter can be considerably augmented by an increase in the thermionic cathode surface. Voltampere and spectroscopic characteristics are measured for different caesium vapour pressures. It is concluded that the current increase due to the cathode surface enlargement is dependent on the plasma penetration in the cathode cavity. E P Busygin et al;Z/z Tckh Fiz, 39 (II), Nov 1969, 2119-2124 (01
Russian). I8 424. On Discharge Analysis
218
discharge formation in tubes. (USSR) formation in low pressure gas-filled tubes is of experimental data shows that the primary process
studied. has the
character of a one-electrode discharge propagated through the tube. The transition from one-electrode to glow discharge is connected with the change of the field in the cathode region and with generation of potential and ionization waves. L N Tunitskiy and E M Cherkasov, Z/I Tcklr Fi:. 39 (I 2). net 1969. 21 73-2176 (iu Rtrminrr). I8 425. Investigation of a limited discharge with a heated cathode in magnetic field. (USSR) Results arc presented of an experimental investigation of a discharge with a limited cross-section in helium prcssurc range of 5 IO n to 0.2 torr with heated tungsten cathode in magnetic feld. The transversal distribution of the plasma density is measured. It is shown that this transversal distribution is determined by charged particle diffusion. At pressures below 5 lo-’ torr a considerable disagrccmcnt between espsrimental data and calculated values is observed. 0 V Kozak and L L Masechnik, Z/r T&/I Fiz, 39 (12). Dec. 1969, 2 177-2182 (in Russinn). 18 426. Excitation and ionization processes in the plasma of a helium microwave discharge. (USSR) The relative and absolute intensities of spectral lines and the ionization frequency in a stationary helium microwave discharge arc determined. The experimental data are compared with calculated values and also with known values for the discharge column of a dc discharge. Electrons with high energy are found in the investigated type of discharge. At a helium pressure of 5 torr the electron energy distribution is close to Maxwellian. A I Maksimov, Z/I Tekh Fi:, 39 (I I ), No\! 1969, 1989-l 996 (iu Rwsimr). I8 427. Investigation of He’ ion motion in He in crossed electric and magnetic fields. (USSR) He+ ion drift in helium gas in the pressure range 10-?-3’. IO ~’ torr is experimentally investigated for the case of crossed electric and magnetic fields. The ion mobility is determined as a function of the gas pressure. L L Pasechnik and V V Yagola, Z/I Tekh Fiz, 39 (IZ), Dee 1969, 2198-2202 (i/r Russian). 18 428. Electron emission on phase transformation in SbSI. (USSR) Exo-electron emission at phase transformation in SbSI was measured with the aid of an electron counter. Maximum electron emission was observed at the temperature increase in the region of the phase transformation. Preliminary X-ray irradiation of SbSl considerably increases exo-electron emission at phase transformation. From this observation it is concluded that the exo-electron emission depends on structural defects. V V Kedabichus et al, Fiz Twrd Teh, 11 (12). Dee 1969, 3615-3617 (in
RmCnl).
I8 429. Energy spectra of electrons released in collisions between fast alkali metal atoms and helium and neon atoms. (USSR) The energy spectra of electrons liberated on ionization due to collisions between two neutral atoms are studied. The experimental vacuum system is described and results are presented for alkali metal atom energies of 200 to 3000 eV, colliding with He and Ne gas, at a pressure of 5 Y IO-’ torr. A retarding potential technique is used to determine the energy spectra of electrons moving perpendicularly to the direction of the primary atom beam. The experimental results are discussed. V I Ogurtsov and Yu F Bydin, Z/I Eksper Teor Fiz, 57 (6), Dee 1969, 1908-I 916 (in Russian). I8 ~37 430. Equilibrium thermodynamic analysis of the barium aluminatetungsten system. (USSR) Porous tungsten impregnated with barium aluminate is extensively used as an efficient thermionic emitter in vacuum and in low pressure devices. A thermodynamic analysis of the equilibrium pressure of barium accompanying the reactions due to interaction between barium aluminate and tungsten, is presented. The value obtained for the barium partial pressure is I Y IO-” torr, at the operating temperature of the impregnated cathode. G A Meerson et al, Izv Akad Nauk SSSR Neorg Muter, 5 (l2), Dee 1969, 2227-2229 (in R~rssiurr).