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Compound ion-resonance mass spectrometer
VACUUM ('htssified Abstracts Abstract No. ..d~ofo~n~
Note by J. 11. Leek & A. Riddoch llrit. J. Appl. l'hqs. 7 April 1936 15:|-155
43,II
II
~
Vacuum
Apparatus and Contd
Auxiliaries
~
II
5 ,uA, and calibration characteristics were measured for air. The discharge voltage was then increased t - 4,000 V. causing an immediate rise to 100 p.A b u t after 200 hours the ultimate pressure reading fell to 1 uA. The calibrations were then repeated. After 10 hrs. plots of gauge current against pressure or voltage showed'typical exponential curves. After 200 hrs. the plots were s t r a i g h t lines showing discharge c u r r e n t to be proportional to (a) voltage at c o n s t a n t pressure and (b) pressure at c o n s t a n t voltage. The gauge sensitivity fell over the 2(10 hr. period, b u t calihration curves remained stable thereafter. F u r t h e r extensive baking enabied the range 10 -~ to 10 "7 ram. tlg lo be investigated. Straight line current-pressure characterisities were obtained in this range, trot a sharp discontinuity with a sudden fall in current was observed at a b o u t 10 -s mm. /tg. The results indicate a change in the n a t u r e of the eh'ctrodes during the first 200 hrs. operation. One explanation m a y be the depositmn . f a carbon layer on the cathode surfaces, which has been observed all t h r o u g h the experin{ents.
Penning Gauge as Leak Detector See A b s t r a c t No,: 114'II
22 --
44:11
MEASURING
PLANT
(VACUUM)
--
22
Optical Instruments for the Vacuum Ultra-Violet See Abstract No.: l l O . ' I
45.'II
Artmlo I, 3" A. (;. Edwards ,.5, (lot. 1!t55 93. I08
Vacuum Research and the Mass Spectrometer United Kingdom. l)espite the widespread use of various v a c u u m ~cchniques m a n y of the basic p h e n o m e n a observed in routine applications are not well maderstood. The investigation of these processes either in specially designed experiments, or by observations on s t a n d a r d p l a n t is assisted if the partial pressure of a single gas can be measured when others are present. This is possible by several methods, b u t mass-spectrometric analysis is by far the m o s t general and convenient technique. The suitability of various mass spectrometers for v a c u u m studies is discussed and illustrated b y reference to accotmts of experimental work. Particular attention is given to certain new types and an a t t e m p t made to assess their potentialities in this field.
Compound Ion-Resonance Mass Spectrometer l.rni/ed S/ales. ;\ new mass spectrometer is proposed which consists essentially of a h,w resolution ISO instru-
Art ich, hy C. F. Robinson ltet:. Nci. I*~slrum. 27, F e b . 1956 88-89
17.II
ment and a cyclotron in series. Its a d v a n t a g e s over the classical cyclotron, the ~>megatron and the mass svnchro meter arc its freedom fro,n space-charge effects, discrimination, and gas scattering; in signal available and in the possibility of differential p u m p i n g . I t retains the characteristics of having a tim. resolution depending only on i n s t r u m e n t p a r a m e t e r s and the e:'m of the ion involved. The working principle of the new i n s t r u m c n t is ext~lained in detail. Using a symmetrical square wave as the gap voltage the resolving power is m o d e r a t e b u t resolving powers of several thou.~and are theoretically possible with sine wave voltages, lint only with a corresponding loss of efficiency. Since the ionisation region in this i n s t r u m e n t is physically and electrically separate from the resolvin~ system, a high degree of differential p u m p i n g is possible between the latter and the ion source.
Servo Controlled Leak for Mass Spectrometer See . \ b s t r a c t No.: 105/If
4S.,II
Modern Methods of Leak Detection ,%,c .\b~tvact No.: 21;I
I~1/I1
Leak Detector See A b s t r a c t No.: 110!II
.',ulI I .krtieh, b y ('. R. Wort hington J . ,b'ci. l n s t r u m . 33, F o b . 1956 66-69
244
Small Angle X - R a y Diffraction Unit ..tustralia. A small angle x-rav diffraction unit consisting of a rotating anode x-ray tube and m" evacuated x-ray camera is described. The x-ray camera can resolve a spacing of 1,000 :\ with a separation of 2 lines per nnn. at the x-ray film. P h o t o g r a p h s of the first twelve orders of moist collagen have been obtained, full,,resolved, with exposures of less t h a n one hour. (.'t uther)
l'acuum I'ol. l V1
October, 1956
Note by J. 11. Leek & A. Riddoch llrit. J. Appl. l'hqs. 7 April 1936 15:|-155
43,II
II
~
Vacuum
Apparatus and Contd
Auxiliaries
~
II
5 ,uA, and calibration characteristics were measured for air. The discharge voltage was then increased t - 4,000 V. causing an immediate rise to 100 p.A b u t after 200 hours the ultimate pressure reading fell to 1 uA. The calibrations were then repeated. After 10 hrs. plots of gauge current against pressure or voltage showed'typical exponential curves. After 200 hrs. the plots were s t r a i g h t lines showing discharge c u r r e n t to be proportional to (a) voltage at c o n s t a n t pressure and (b) pressure at c o n s t a n t voltage. The gauge sensitivity fell over the 2(10 hr. period, b u t calihration curves remained stable thereafter. F u r t h e r extensive baking enabied the range 10 -~ to 10 "7 ram. tlg lo be investigated. Straight line current-pressure characterisities were obtained in this range, trot a sharp discontinuity with a sudden fall in current was observed at a b o u t 10 -s mm. /tg. The results indicate a change in the n a t u r e of the eh'ctrodes during the first 200 hrs. operation. One explanation m a y be the depositmn . f a carbon layer on the cathode surfaces, which has been observed all t h r o u g h the experin{ents.
Penning Gauge as Leak Detector See A b s t r a c t No,: 114'II
22 --
44:11
MEASURING
PLANT
(VACUUM)
--
22
Optical Instruments for the Vacuum Ultra-Violet See Abstract No.: l l O . ' I
45.'II
Artmlo I, 3" A. (;. Edwards ,.5, (lot. 1!t55 93. I08
Vacuum Research and the Mass Spectrometer United Kingdom. l)espite the widespread use of various v a c u u m ~cchniques m a n y of the basic p h e n o m e n a observed in routine applications are not well maderstood. The investigation of these processes either in specially designed experiments, or by observations on s t a n d a r d p l a n t is assisted if the partial pressure of a single gas can be measured when others are present. This is possible by several methods, b u t mass-spectrometric analysis is by far the m o s t general and convenient technique. The suitability of various mass spectrometers for v a c u u m studies is discussed and illustrated b y reference to accotmts of experimental work. Particular attention is given to certain new types and an a t t e m p t made to assess their potentialities in this field.
Compound Ion-Resonance Mass Spectrometer l.rni/ed S/ales. ;\ new mass spectrometer is proposed which consists essentially of a h,w resolution ISO instru-
Art ich, hy C. F. Robinson ltet:. Nci. I*~slrum. 27, F e b . 1956 88-89
17.II
ment and a cyclotron in series. Its a d v a n t a g e s over the classical cyclotron, the ~>megatron and the mass svnchro meter arc its freedom fro,n space-charge effects, discrimination, and gas scattering; in signal available and in the possibility of differential p u m p i n g . I t retains the characteristics of having a tim. resolution depending only on i n s t r u m e n t p a r a m e t e r s and the e:'m of the ion involved. The working principle of the new i n s t r u m c n t is ext~lained in detail. Using a symmetrical square wave as the gap voltage the resolving power is m o d e r a t e b u t resolving powers of several thou.~and are theoretically possible with sine wave voltages, lint only with a corresponding loss of efficiency. Since the ionisation region in this i n s t r u m e n t is physically and electrically separate from the resolvin~ system, a high degree of differential p u m p i n g is possible between the latter and the ion source.
Servo Controlled Leak for Mass Spectrometer See . \ b s t r a c t No.: 105/If
4S.,II
Modern Methods of Leak Detection ,%,c .\b~tvact No.: 21;I
I~1/I1
Leak Detector See A b s t r a c t No.: 110!II
.',ulI I .krtieh, b y ('. R. Wort hington J . ,b'ci. l n s t r u m . 33, F o b . 1956 66-69
244
Small Angle X - R a y Diffraction Unit ..tustralia. A small angle x-rav diffraction unit consisting of a rotating anode x-ray tube and m" evacuated x-ray camera is described. The x-ray camera can resolve a spacing of 1,000 :\ with a separation of 2 lines per nnn. at the x-ray film. P h o t o g r a p h s of the first twelve orders of moist collagen have been obtained, full,,resolved, with exposures of less t h a n one hour. (.'t uther)
l'acuum I'ol. l V1
October, 1956