Model TK1865 dual reservoir bath cryostat
|Ports (optics/electrical feedthroughs)||Four on the side of the cryostat *|
|Maximum port clear aperture||28 mm (77 K radiation shield limit)|
|Electrical connector (standard)||10 pint low-voltage electrical connector|
|Optic axis height||20 mm|
|Headroom (when cold)||77 mm|
|(Helium temperature) cold plate diameter||200 mm|
|Liquid helium capacity||6.0 litres|
|Liquid nitrogen capacity||6.5 litres|
|Hold time, subsequent fill (typical, not including initial fill)||> 30 days (ports blanked, no wiring)|
|10-14 days (reduced band mm detector)|
|8 days (broadband mm detector)|
|Liquid nitrogen hold time (approx)||60-80 hours|
|Cryostat diameter||299 mm|
|Cryostat height (excluding lifting handle)|
|Mass (empty)||45 kg|
This dual reservoir cryostat has a 77K liquid nitrogen Dewar and jacket, and an intermediate 40K cold helium gas cooled radiation shield, all surrounding a central 4.2K liquid helium Dewar. Liquid nitrogen hold time is typically sixty to eighty hours, hence the cryostat will remain cold over a weekend with no user intervention required. A TK1865 cryostat with no components inside and all ports fully blanked will hold liquid helium for about thirty days. When used as a reduced band mm wave detector the liquid helium will last about ten to fourteen days.
Readying the cryostat for operation by evacuating, and then cooling to liquid helium temperature takes about fourteen hours, which includes a tweleve hour liquid nitrogen pre-cool. The longer pre-cool of this cryostat compared to the TK1810 and TK1813 cryostats is recommended, so that the gas cooled radiation shield has time to reach 77K before the liquid helium is transferred into the cryostat. If necessary, a shorter pre-cool can be carried out, but this will require excessive use of the more expensive liquid helium cryogen. Refer to the manual for further details.
We often customise cryostats to suit customer applications. For example, extended radiation shields can be built that give a greater height above the 4.2K cold plate to accommodate larger apparatus. A mini-refrigerator or bespoke customer equipment can then be mounted in the cryostat.