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Ultra-high vacuum rotary manipulator with direct cooling
Ultra-high cooling received
in final
0 Auciello*, de Energia
form
vacuum 14 March
E U Alonso* and Atdmica, Universidad
rotary
manipulator
with
direct
1976 R A Baragiola, Centro Atdmico Bariloche. National de Cuyo, Bariloche. Argentina
lnstituto
de Fisica
‘Dr Jose
Balseiro’.
Comisidn
National
A high torque specimen manipulator for use in ultra-high vacuum is described. It allows the specimen to be rotated through 360” and translated 1 cm along the rotation axis. A special feature of this design is that the specimen can be cooled in a direct simple way.
1. Introduction
It is often difficult to combine efhcient cooling of the specimen with continuous rotation about an axis in ultra-high vacuum manipulators. This difficulty has been overcome in our design by the incorporation of a polytetrafluorethylene (PTFE) Mills seal (Mills 1972). Our manipulator is used in the study of sputtering by ion impact of thin films evaporated onto a watercooled quartz-crystal resonator, a technique first described by McKeown (McKeown 1961). The rotary motion serves two purposes, namely the study of sputtering yields as a function of the angle of incidence of the ion beam and bringing the quartzcrystal surface into a horizontal position to face an evaporation gun for i/r situ uhv thin film deposition. For this application the manipulator is mounted with its axis of rotation in a horizontal position.
rotated through 90” so it can ‘see’ the evaporation source through hole G which is drilled in cylinder F. Guides G’ prevent this cylinder from rotating.
-M
2. Design
and
construction -L
diagram of the device is shown in Figure 1. The specimen is mounted on the copper sample holder A. In our application, a thin mica foil is inserted between sample and sample holder to achieve electrical isolation of the former. By simply using a screwdriver in the slot A’, the position of the holder can be varied until the line defined by the axis Y is contained in the plane defined by the sample surface. Spring loaded electrical contacts C keep the target in place. These contacts can slide on holes made through machinable ceramic insulators D. Electrical conductors are introduced through hole E and then connected to feedthroughs in another port of the vacuum system. By applying a positive potential to the target and a negative potential to shield E’ with respect to the grounded cylinder F and slit D’, secondary electrons are prevented from introducing errors in the measurements of ion beam currents. The target block B is machined out of a cylindrical piece of copper (side view, Figure l), in such a way that it does not intercept the ion beam when rotation is carried out through angles from 0” to f90” as measured between the beam axis Z and the normal to the target. In our application the manipulator is mounted with the axis Y horizontal. For itr situ thin film deposition the target is
A
* Fellow of the Consejo National de Investigaciones Cientificas y Tecnicas, Argentina. Vacuum/Volume 26/number 8.
Pergamon
Press/Printed
in Great
Figure 1. Cross sectional view of the ultra-high vacuum manipulator showing a side view of target block B and a section X-X in which a construction detail of the cooling circuit in B can be seen. Britain
349
0 Auciello,
E V Alonso
and R A Baragiola:
Ultra-high vacuum rotary manipulator with direct cooling
The refrigerant passes through the inlet and outlet stainlesssteel tubes H and H’ of 3 mm inside diameter each, and through the circuit in the target block B (see section X-X, Figure I). PTFE rings U seal the cooling circuit when flange V is hnally clamped to S. A stainless-steel tube I, inert gas welded to the target block B is used to transmit the motion through the Mills seal. This seal consists of a double cone PTFE grommet J clamped against a standard 70 mm outside diameter uhv flange K. This flange has six screwed holes not seen in the figure which are used to attach the manipulator to a standard 38 mm inside diameter port of a uhv system. By turning the drum N, which is attached to the nut R by the brake 0, the motion is transmitted through the guides Q to the screwed column S which is locked to the tube I by the two screws T. The angular position is measured with the aid of a graduated disc M and an index in piece L which is locked to the flange K. Friction between rotating parts are reduced by means of PTFE rings P. When R is rotated with N fixed by the brake L’, the screwed column S is driven along the Y axis with the constraint against rotation being supplied by the guides Q. Displacement along Y is measured by a scale engraved in a flat milled in the screw S.
350
3. Performance
The manipulator has proved to be leak tight within the sensitivity of our helium leak detector, IO- lo torr It./seg, even under motion and with liquid nitrogen circulating through the cooling circuit. 4. Conclusions
The use of a PTFE Mills seal gives a simple solution to the problem of direct cooling of a specimenin ultra-high vacuum manipulators.At the sametime the construction iscompact and allows the transmissionof high torques, Acknowledgements
We thank Mr F E Tutzauer for valuable suggestionsand for making the device. We acknowledgepartial support from the Multinational Program in Physics of the Organization of American States. References
D McKeown, Rev J C Mills, Rer Sci
Sci hrr, 32, 196 I, 133. Iturr, 43, 1942, 819.
in final
0 Auciello*, de Energia
form
vacuum 14 March
E U Alonso* and Atdmica, Universidad
rotary
manipulator
with
direct
1976 R A Baragiola, Centro Atdmico Bariloche. National de Cuyo, Bariloche. Argentina
lnstituto
de Fisica
‘Dr Jose
Balseiro’.
Comisidn
National
A high torque specimen manipulator for use in ultra-high vacuum is described. It allows the specimen to be rotated through 360” and translated 1 cm along the rotation axis. A special feature of this design is that the specimen can be cooled in a direct simple way.
1. Introduction
It is often difficult to combine efhcient cooling of the specimen with continuous rotation about an axis in ultra-high vacuum manipulators. This difficulty has been overcome in our design by the incorporation of a polytetrafluorethylene (PTFE) Mills seal (Mills 1972). Our manipulator is used in the study of sputtering by ion impact of thin films evaporated onto a watercooled quartz-crystal resonator, a technique first described by McKeown (McKeown 1961). The rotary motion serves two purposes, namely the study of sputtering yields as a function of the angle of incidence of the ion beam and bringing the quartzcrystal surface into a horizontal position to face an evaporation gun for i/r situ uhv thin film deposition. For this application the manipulator is mounted with its axis of rotation in a horizontal position.
rotated through 90” so it can ‘see’ the evaporation source through hole G which is drilled in cylinder F. Guides G’ prevent this cylinder from rotating.
-M
2. Design
and
construction -L
diagram of the device is shown in Figure 1. The specimen is mounted on the copper sample holder A. In our application, a thin mica foil is inserted between sample and sample holder to achieve electrical isolation of the former. By simply using a screwdriver in the slot A’, the position of the holder can be varied until the line defined by the axis Y is contained in the plane defined by the sample surface. Spring loaded electrical contacts C keep the target in place. These contacts can slide on holes made through machinable ceramic insulators D. Electrical conductors are introduced through hole E and then connected to feedthroughs in another port of the vacuum system. By applying a positive potential to the target and a negative potential to shield E’ with respect to the grounded cylinder F and slit D’, secondary electrons are prevented from introducing errors in the measurements of ion beam currents. The target block B is machined out of a cylindrical piece of copper (side view, Figure l), in such a way that it does not intercept the ion beam when rotation is carried out through angles from 0” to f90” as measured between the beam axis Z and the normal to the target. In our application the manipulator is mounted with the axis Y horizontal. For itr situ thin film deposition the target is
A
* Fellow of the Consejo National de Investigaciones Cientificas y Tecnicas, Argentina. Vacuum/Volume 26/number 8.
Pergamon
Press/Printed
in Great
Figure 1. Cross sectional view of the ultra-high vacuum manipulator showing a side view of target block B and a section X-X in which a construction detail of the cooling circuit in B can be seen. Britain
349
0 Auciello,
E V Alonso
and R A Baragiola:
Ultra-high vacuum rotary manipulator with direct cooling
The refrigerant passes through the inlet and outlet stainlesssteel tubes H and H’ of 3 mm inside diameter each, and through the circuit in the target block B (see section X-X, Figure I). PTFE rings U seal the cooling circuit when flange V is hnally clamped to S. A stainless-steel tube I, inert gas welded to the target block B is used to transmit the motion through the Mills seal. This seal consists of a double cone PTFE grommet J clamped against a standard 70 mm outside diameter uhv flange K. This flange has six screwed holes not seen in the figure which are used to attach the manipulator to a standard 38 mm inside diameter port of a uhv system. By turning the drum N, which is attached to the nut R by the brake 0, the motion is transmitted through the guides Q to the screwed column S which is locked to the tube I by the two screws T. The angular position is measured with the aid of a graduated disc M and an index in piece L which is locked to the flange K. Friction between rotating parts are reduced by means of PTFE rings P. When R is rotated with N fixed by the brake L’, the screwed column S is driven along the Y axis with the constraint against rotation being supplied by the guides Q. Displacement along Y is measured by a scale engraved in a flat milled in the screw S.
350
3. Performance
The manipulator has proved to be leak tight within the sensitivity of our helium leak detector, IO- lo torr It./seg, even under motion and with liquid nitrogen circulating through the cooling circuit. 4. Conclusions
The use of a PTFE Mills seal gives a simple solution to the problem of direct cooling of a specimenin ultra-high vacuum manipulators.At the sametime the construction iscompact and allows the transmissionof high torques, Acknowledgements
We thank Mr F E Tutzauer for valuable suggestionsand for making the device. We acknowledgepartial support from the Multinational Program in Physics of the Organization of American States. References
D McKeown, Rev J C Mills, Rer Sci
Sci hrr, 32, 196 I, 133. Iturr, 43, 1942, 819.