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Desorption experiments in an ultra-high vacuum system, pumped by molecular sieve trapped oil diffusion pumps
Classified Abstracts 344--349
Classified A b s t r a c t s Abstractmg Editor's Note. The label munedtately following the title oJ each item denotes country o f origin o f pubhcatton, and that at the end o f each abstract mdwates country oJ origin o f u ork (where known). G e n e r a l V a c u u m Science and E n g i n e e r i n g 10.
bed b.~. or loosely attached to, the ~all~ generalb exceeds by far that r e m a m m g free in the enclosed volume The a u t h o r investigates the influence of the a d s o r b e d ga~ on the pressure distribution existing in long tubes, making use of a simplified form of the d~fferenttal equation for the diffusion process Specific solutions are g~ven ~hlch after generahzatton to other s2~stems ot different geometry can be u~ed t\,r the e',aluauon of the time c o n s t a n t of pressure equahzatlon, the calculation of flow impedance and cold trap effic~enc~ ( Germam l w J s
V a c u u m S c i e n c e and T e c h n o l o g y lO
21
344. The pumping speed of titanium sputter pumps in ultra-high
vacuum. ( Get ma~t~ ) In the pre~sure ranges of lO ~and I0 ~t'torr t h e p u m p l n g s p e e d o l a titanium sputter p u m p is measured by comparr.,on v, lth the k n o ~ n conductance of a d m p h r a g m After s~mple bake-out an ultimate pressure ol 5 10 ~'' torr ts obtained The p u m p i n g speed, ho~,,e~er, m tile I o ~ e r pressure range,, [s n o u c e a b b reduced c o m p a r e d to that of a d~ffus~on p u m p The performance of a sputter p u m p ~s considerably improved b2, a short mject~on of argon After that treatment the u l u m a t e pressure drop~ to 3-7 10 ~ t o r r a n d t h e p u m p m g s p e e d c h a r a c t e r ~ t l c t ~ q u a h t a t l v e l y t h a t o l a diffusion p u m p A ~trong u m e dependence of the p u m p i n g speed is observed ~,~hen tile gas m.lectlon i,, kept constant In the range of l(I -~' torr, it takes a b o u t 24 h o u r s for e q u l h b r l u m to be reached The gas b a c k s t r e a m m g o l t h e ~ p u t t e r p u m p ~s--ln ~_ontrast to a diffusion p u m p ~ b o t h pre.,,sure and time dependent The reduction ot the p u m p i n g speed of a p u m p before it has been argon treated is related to the observed reduction of the intensity, of the ga~, d~scharge belo~ ~ 10 " t o r r (S~tit_-erlalldl I ~uthorl
J Neubert, I aAattt~l Techm~ 13 ( I ) Feb 1964, 19-23 12 61 347. Units in ~acuum measurement. (Great BtHam) The term pressure " begins to lose its con,.entlona[ meflnmg s o m e ~ h e r e m t h e , . e r } h J g h x a c t l u m r e g l o n If ~e could construct an ~ontzatton gauge of absolutel,, k n o w n s a m p h n g el~c~ency it would be an absolute gauge ~hlch could be cahbrated to read molecules cc F r o m the fact that at a pressure of 760 tort, there are 6 02 IO t-' molecules.mole 1 molecule. M ~ c o r r e s p o n d s to a " pressure ol 2 83 10 --'~ torr The a u t h o r suggests the use of a logarithmic dens[t~ scale ~ t h a zero at 1 molecule.'M" A pressure ol 1 10-" torr ~ o u l d then c o r r e s p o n d to 16 55 log denstt.,, umts O t h e r ~alues are gt~en belo~ Pressure m tort 760 1 10 ~ 10 ~ 10 -~ 10 -~-' log dens[t'., st.ale 25 4~ 22 55 19 5", 16 55 13 55 10 55 F o r certain purposes (residual ga,, analys~ ere I a hnear densJt,, scale m~ght be prelerable But ~hate'.er the final choice, the a u t h o r i%ol the opinion that the basic '.aCt.lum unit in high ".,aduunl ~ o r k should be one of molecular den~H3 rather than pressure
E F~scher 2rid Furopean [a~ S3mp. 5-7 June. 1963. 261-265 R u d o l p h A Lang kerlag, E s c h ( T a u n t t s l
11.
Production
of
Lo~
Pressure
11 21 25 345. Desorptmn experiments m an ultra-high ~acuum s~stem, pumped b) molecular s]ese trapped od diffusion pumps. ( Ge~ m a n ~ )
~A J S F T \~,orrel \atute. 199 (4~921 '~ Aug 1963 476
In an ultra-h~gh ~acuum s~stem p u m p e d by oil d~ffuslon pump~ with molecular siege traps the ~on current of a gauge gt~es no indication of the c o n t a m i n a t i o n of the s~sten't b} adsorbed od molecules and their crack product,-, At Io~ coverage the n u m b e r o f backstreamed od molecules Js measured alter a certain p n m p l n g time b~ isolating tile ~3stem l r o m the p u m p s and b', a thermal d e s o r p u o n of the adsorbed molecule~ F r o m a n u m b e r of such desorptlon c~,cles a h n e a r increase of the coverage with oil molecules in the first ~eek,, ~s deduced ~htch gl~es a c o n t a m i n a tion rate of 10" tool c cm-" da3 for a carefull.~ dega,,sed laborator.,, set-up IGe~man~l ( Author} S G a r b e 2nd Emopean lac Slmp 5-7 June. 1963 R u d o l p h A Lang \ e r l a g E ~ c h ( T a u n u ~ )
12.
12
348. Units of ~acuum measurement.
295-304.
12 22 61 Problems in establishing standards for vacuum measurement and m calibrating ~acuum gauges. See Abstr N o 449 14
61
&tram)
The a u t h o r refers to pre~lou,, proposals ol a logarithmic denslt~ ~cale (see Abstr N o 347 abo~e) and p r o p o s e s a logarithmic pressure scale ot his o ~ n defined by p.t = - l o g , . rpres~ure in atmo,,pheresl Thl~ leads to the follo,~ mg relatl~,e value,, Pressure m t o r r 760 l 10 a l0 " l0 9 10-t_, p4 0 29 59 89 119 149 T h ~ scale has the advantage of increasing ~ [th increasing v a c u u m and being restricted to small n u m b e r s Moreover it is related to the simple mercur~ manometer, the readmg~ ot ',~hlch unhke those of the ionization gauge or mass ~pectrometer are Independent of the gas they measure and in~anant from da} to da~ It must be emphasized hov, e~er. that logarithmic ,,tales. h o ~ e ~ e r convenient and neat they ma~ be m describing the state of a v a c u u m s~stem are of httle use in vaLuum engineering, conductances, etc In these case.-, the customar2, hnear scale is still m,,aluable ~.~. J s J Cuthbert, Nature, 2 0 1 ( 4 9 1 4 ) , 4 J a n 1964 61
M e a s u r e m e n t o f L o w Pressure
12
(G~eat
16
346. The calculation of the pressure distribution in vacuum systems, taking into account adsorptmn and condensation.
(Germany)
349. Theory of linearity of hot cathode ,onizatton gauge.
in a high or ultra-high ~acuum system, the quantlt~ of gas adsor-
C Y H'.,.a, ActaPh~s Smtca, 19(2). 1963. 73-82 157
12 22 ( Clsma)
Classified A b s t r a c t s Abstractmg Editor's Note. The label munedtately following the title oJ each item denotes country o f origin o f pubhcatton, and that at the end o f each abstract mdwates country oJ origin o f u ork (where known). G e n e r a l V a c u u m Science and E n g i n e e r i n g 10.
bed b.~. or loosely attached to, the ~all~ generalb exceeds by far that r e m a m m g free in the enclosed volume The a u t h o r investigates the influence of the a d s o r b e d ga~ on the pressure distribution existing in long tubes, making use of a simplified form of the d~fferenttal equation for the diffusion process Specific solutions are g~ven ~hlch after generahzatton to other s2~stems ot different geometry can be u~ed t\,r the e',aluauon of the time c o n s t a n t of pressure equahzatlon, the calculation of flow impedance and cold trap effic~enc~ ( Germam l w J s
V a c u u m S c i e n c e and T e c h n o l o g y lO
21
344. The pumping speed of titanium sputter pumps in ultra-high
vacuum. ( Get ma~t~ ) In the pre~sure ranges of lO ~and I0 ~t'torr t h e p u m p l n g s p e e d o l a titanium sputter p u m p is measured by comparr.,on v, lth the k n o ~ n conductance of a d m p h r a g m After s~mple bake-out an ultimate pressure ol 5 10 ~'' torr ts obtained The p u m p i n g speed, ho~,,e~er, m tile I o ~ e r pressure range,, [s n o u c e a b b reduced c o m p a r e d to that of a d~ffus~on p u m p The performance of a sputter p u m p ~s considerably improved b2, a short mject~on of argon After that treatment the u l u m a t e pressure drop~ to 3-7 10 ~ t o r r a n d t h e p u m p m g s p e e d c h a r a c t e r ~ t l c t ~ q u a h t a t l v e l y t h a t o l a diffusion p u m p A ~trong u m e dependence of the p u m p i n g speed is observed ~,~hen tile gas m.lectlon i,, kept constant In the range of l(I -~' torr, it takes a b o u t 24 h o u r s for e q u l h b r l u m to be reached The gas b a c k s t r e a m m g o l t h e ~ p u t t e r p u m p ~s--ln ~_ontrast to a diffusion p u m p ~ b o t h pre.,,sure and time dependent The reduction ot the p u m p i n g speed of a p u m p before it has been argon treated is related to the observed reduction of the intensity, of the ga~, d~scharge belo~ ~ 10 " t o r r (S~tit_-erlalldl I ~uthorl
J Neubert, I aAattt~l Techm~ 13 ( I ) Feb 1964, 19-23 12 61 347. Units in ~acuum measurement. (Great BtHam) The term pressure " begins to lose its con,.entlona[ meflnmg s o m e ~ h e r e m t h e , . e r } h J g h x a c t l u m r e g l o n If ~e could construct an ~ontzatton gauge of absolutel,, k n o w n s a m p h n g el~c~ency it would be an absolute gauge ~hlch could be cahbrated to read molecules cc F r o m the fact that at a pressure of 760 tort, there are 6 02 IO t-' molecules.mole 1 molecule. M ~ c o r r e s p o n d s to a " pressure ol 2 83 10 --'~ torr The a u t h o r suggests the use of a logarithmic dens[t~ scale ~ t h a zero at 1 molecule.'M" A pressure ol 1 10-" torr ~ o u l d then c o r r e s p o n d to 16 55 log denstt.,, umts O t h e r ~alues are gt~en belo~ Pressure m tort 760 1 10 ~ 10 ~ 10 -~ 10 -~-' log dens[t'., st.ale 25 4~ 22 55 19 5", 16 55 13 55 10 55 F o r certain purposes (residual ga,, analys~ ere I a hnear densJt,, scale m~ght be prelerable But ~hate'.er the final choice, the a u t h o r i%ol the opinion that the basic '.aCt.lum unit in high ".,aduunl ~ o r k should be one of molecular den~H3 rather than pressure
E F~scher 2rid Furopean [a~ S3mp. 5-7 June. 1963. 261-265 R u d o l p h A Lang kerlag, E s c h ( T a u n t t s l
11.
Production
of
Lo~
Pressure
11 21 25 345. Desorptmn experiments m an ultra-high ~acuum s~stem, pumped b) molecular s]ese trapped od diffusion pumps. ( Ge~ m a n ~ )
~A J S F T \~,orrel \atute. 199 (4~921 '~ Aug 1963 476
In an ultra-h~gh ~acuum s~stem p u m p e d by oil d~ffuslon pump~ with molecular siege traps the ~on current of a gauge gt~es no indication of the c o n t a m i n a t i o n of the s~sten't b} adsorbed od molecules and their crack product,-, At Io~ coverage the n u m b e r o f backstreamed od molecules Js measured alter a certain p n m p l n g time b~ isolating tile ~3stem l r o m the p u m p s and b', a thermal d e s o r p u o n of the adsorbed molecule~ F r o m a n u m b e r of such desorptlon c~,cles a h n e a r increase of the coverage with oil molecules in the first ~eek,, ~s deduced ~htch gl~es a c o n t a m i n a tion rate of 10" tool c cm-" da3 for a carefull.~ dega,,sed laborator.,, set-up IGe~man~l ( Author} S G a r b e 2nd Emopean lac Slmp 5-7 June. 1963 R u d o l p h A Lang \ e r l a g E ~ c h ( T a u n u ~ )
12.
12
348. Units of ~acuum measurement.
295-304.
12 22 61 Problems in establishing standards for vacuum measurement and m calibrating ~acuum gauges. See Abstr N o 449 14
61
&tram)
The a u t h o r refers to pre~lou,, proposals ol a logarithmic denslt~ ~cale (see Abstr N o 347 abo~e) and p r o p o s e s a logarithmic pressure scale ot his o ~ n defined by p.t = - l o g , . rpres~ure in atmo,,pheresl Thl~ leads to the follo,~ mg relatl~,e value,, Pressure m t o r r 760 l 10 a l0 " l0 9 10-t_, p4 0 29 59 89 119 149 T h ~ scale has the advantage of increasing ~ [th increasing v a c u u m and being restricted to small n u m b e r s Moreover it is related to the simple mercur~ manometer, the readmg~ ot ',~hlch unhke those of the ionization gauge or mass ~pectrometer are Independent of the gas they measure and in~anant from da} to da~ It must be emphasized hov, e~er. that logarithmic ,,tales. h o ~ e ~ e r convenient and neat they ma~ be m describing the state of a v a c u u m s~stem are of httle use in vaLuum engineering, conductances, etc In these case.-, the customar2, hnear scale is still m,,aluable ~.~. J s J Cuthbert, Nature, 2 0 1 ( 4 9 1 4 ) , 4 J a n 1964 61
M e a s u r e m e n t o f L o w Pressure
12
(G~eat
16
346. The calculation of the pressure distribution in vacuum systems, taking into account adsorptmn and condensation.
(Germany)
349. Theory of linearity of hot cathode ,onizatton gauge.
in a high or ultra-high ~acuum system, the quantlt~ of gas adsor-
C Y H'.,.a, ActaPh~s Smtca, 19(2). 1963. 73-82 157
12 22 ( Clsma)