INFICON UHV Bakeable Sensor - Manual (Page 30)

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UHV Bakeable Sensor Operating Manual
2.4 Providing Improved Cooling for the Sensor
Because of its temperature requirements, the UHV Bakeable Sensor is made
primarily of stainless steel. This poses a difficult problem from the design
standpoint of thermal transfer. The clamping action of the spring and cam
mechanism was found to provide better transfer of heat than other methods,
because it allows continuous contact pressure throughout the temperature cycles
encountered. However, for some applications where the materials are evaporated
at high rate and/or high temperatures, thermal transfer may still be insufficient for
ideal operation of the quartz crystal.
To improve the thermal transfer between the crystal holder and the water-cooled
body of the UHV Bakeable Sensor, a thin washer can be fabricated of easily
deformable metal to insert between the holder and the body. Once fabricated, this
washer will last indefinitely. It can provide a 50% improvement in thermal transfer
between the two parts by increasing the surface contact between the two
non-deformable stainless steel parts.
Both gold and aluminum have been used successfully in this way, but since
aluminum foil is nearly perfect in thickness, it is the first choice. (Gold works only
slightly better.)
Figure 2-3 is a guide to the fabrication of the washer.
Figure 2-3 Guide to fabrication of washer
19 mm
(0.75 in.)
27 mm
(1.06 in.)
Material - Au, Al
Recommended thickness range
0.013 to 0.08 mm (0.0005 to 0.003 in.)