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1. Bakeable weldable Pirani vacuum gauge with BNC or isolated BNC feedthrough
Workshop
notes
and short
contributions
Following a suggestion by a member of our Editorial Board (Dr John Colligon) this new section is intended to be helpful and informative to technicians as well as scientists and technologists. Abstracts are not given. Full references to other papers are not necessarily required.
1. Bakeable Weldable Pirani Vacuum Gauge with BNC or Isolated BNC Feedthrough
Type
A zz!sE?f--
t-1
Bakeable and weldable Pirani vacuum gauges are to be used in the gas feed system of the ionization monitor of the KEK I2 GeV proton synchrotron’. Moreover these gauges are to be used in the automatic control of the ultra-high vacuum system of the electron storage ring’ and the interlock of the high voltage in the vacuum and gas feeder. Since they should be able to resist an intense radiation dose as well as be suitable for ultra-high vacuum which necessitates baking at high temperature, epoxy resin or glass with solder could not be used for vacuum seals. Because no commercially available Pirani gauge fulfils these various requirements simultaneously, an appropriate one has been specially designed and made. As shown in Figure 1, the Pirani gauge consists of a stainless steel tube, a stainless steel stem, platinum wire and a bakeable BNC’ vacuum feedthrough. BNC feedthroughs consist of kovar and ceramic. The Pirani gauge of type B is isolated from the vacuum chamber. The platinum wire is bonded by spot welding using nickel sheet between the platinum wire and the stainless steel stem. Two points are welded at both sides. The
Type
I3
0
20mm
Figure 1. Cross-sectional view of the bakeable Pirani vacuum gauge: l-vacuum fitting, 2, 5-nickel spacer, 3-platinum wire, 4-stainless steel tube, bargon arc-welding, 7-bakeable BNC vacuum feedthrough, 8-stainless steel stem. surfaces of the feedthrough are coated with about 2 pm thick gold for good electrical contact. The BNC connector with the coaxial cable mates to the feedthrough and can be connected or removed quickly. After argon arc-welding the welding surfaces are glass-bead-blasted in vacuum to clean them. The Pirani gauge is tested by a helium leak detector and conforms to a leak rate of less than lo- lo atom cm’ s- ‘. Pirani gauges of this
Figure 2. A photograph of the bakeable Pirani gauge with BNC or floated BNC feedthrough: (a) type A: with BNC feedthrough, (b) type B: with floated BNC feedthrough. Vacuum/volume
28/number
819. Pergamon
Press
LtdlPrinted
in Great
Britain
361
Workshop
notes
and short
contributions
are mechanically solid and safely withstand baking cycles at a temperature of up to 300°C. Thin diameter platinum wire: 25 pm is used. The sensitivity range of the gauge is wide between 20 and 0.003 torr. A commercially available controller, GP-2T-RY4 is used with these gauges. The filament dose is not cut off at atmospheric pressure for a long period time. The resulting assembly is compatible with ultra-high vacuum operation and is resistant to strong ionizing radiation. This type of Pirani gauge has been used in a particle accelerator, a nuclear fusion apparatus and in a molecular physics device. type
362
References 1Annual Report 1973-1976, National Laboratory for High Energy Physics, Japan. 1 K Huke, private communication. 3 H Ishimaru, Vucuum,X,1976,243 4 ULVAC Corporation, 2500 Hagisono, Chigasaki, Kanagawa, Japan. H. Iahimaru National Laboratory for High Energy Physics, Oho-machi, Tsukuba-gun, Ibaraki-ken, 300-32, Japan
notes
and short
contributions
Following a suggestion by a member of our Editorial Board (Dr John Colligon) this new section is intended to be helpful and informative to technicians as well as scientists and technologists. Abstracts are not given. Full references to other papers are not necessarily required.
1. Bakeable Weldable Pirani Vacuum Gauge with BNC or Isolated BNC Feedthrough
Type
A zz!sE?f--
t-1
Bakeable and weldable Pirani vacuum gauges are to be used in the gas feed system of the ionization monitor of the KEK I2 GeV proton synchrotron’. Moreover these gauges are to be used in the automatic control of the ultra-high vacuum system of the electron storage ring’ and the interlock of the high voltage in the vacuum and gas feeder. Since they should be able to resist an intense radiation dose as well as be suitable for ultra-high vacuum which necessitates baking at high temperature, epoxy resin or glass with solder could not be used for vacuum seals. Because no commercially available Pirani gauge fulfils these various requirements simultaneously, an appropriate one has been specially designed and made. As shown in Figure 1, the Pirani gauge consists of a stainless steel tube, a stainless steel stem, platinum wire and a bakeable BNC’ vacuum feedthrough. BNC feedthroughs consist of kovar and ceramic. The Pirani gauge of type B is isolated from the vacuum chamber. The platinum wire is bonded by spot welding using nickel sheet between the platinum wire and the stainless steel stem. Two points are welded at both sides. The
Type
I3
0
20mm
Figure 1. Cross-sectional view of the bakeable Pirani vacuum gauge: l-vacuum fitting, 2, 5-nickel spacer, 3-platinum wire, 4-stainless steel tube, bargon arc-welding, 7-bakeable BNC vacuum feedthrough, 8-stainless steel stem. surfaces of the feedthrough are coated with about 2 pm thick gold for good electrical contact. The BNC connector with the coaxial cable mates to the feedthrough and can be connected or removed quickly. After argon arc-welding the welding surfaces are glass-bead-blasted in vacuum to clean them. The Pirani gauge is tested by a helium leak detector and conforms to a leak rate of less than lo- lo atom cm’ s- ‘. Pirani gauges of this
Figure 2. A photograph of the bakeable Pirani gauge with BNC or floated BNC feedthrough: (a) type A: with BNC feedthrough, (b) type B: with floated BNC feedthrough. Vacuum/volume
28/number
819. Pergamon
Press
LtdlPrinted
in Great
Britain
361
Workshop
notes
and short
contributions
are mechanically solid and safely withstand baking cycles at a temperature of up to 300°C. Thin diameter platinum wire: 25 pm is used. The sensitivity range of the gauge is wide between 20 and 0.003 torr. A commercially available controller, GP-2T-RY4 is used with these gauges. The filament dose is not cut off at atmospheric pressure for a long period time. The resulting assembly is compatible with ultra-high vacuum operation and is resistant to strong ionizing radiation. This type of Pirani gauge has been used in a particle accelerator, a nuclear fusion apparatus and in a molecular physics device. type
362
References 1Annual Report 1973-1976, National Laboratory for High Energy Physics, Japan. 1 K Huke, private communication. 3 H Ishimaru, Vucuum,X,1976,243 4 ULVAC Corporation, 2500 Hagisono, Chigasaki, Kanagawa, Japan. H. Iahimaru National Laboratory for High Energy Physics, Oho-machi, Tsukuba-gun, Ibaraki-ken, 300-32, Japan