An Orange Cryostat on SANDALS
View full-size image
Helium cryostats and CCRs
They use helium as an exchange gas for thermal contact. They are top loading (the sample is mounted at the end of a candle-stick, with the centre of the can at about 1165mm from the bottom of the stick's flange.
The thermal radiation is screened at the sample position through a series of thin aluminium tails (overall thickness can vary: OC100-10 has about 250 μm thickness of aluminium in the beam, OC100-12 has 500 μm).
The overall diameter of the cryostat is 100mm, which is ok for all standard SANDALS cans.
The helium cryostat is free from vibrations (an important detail if you a trying, for example, to supercool an aqueous system) and it's definitely your choice if you are trying to go below 4K (2K is the base temperature you can reach with a standard set up).
You will normally choose a helium cryostat unless:
Closed cycle refrigerator (CCR)
The thermal contact with the cold bath is reached through a cold finger in direct contact with a copper element surrounding the sample can.
The CCR set up in use on SANDALS is bottom loading (needs a crane lifting when you want to change the sample) and therefore the sample set up is quite free.
The thermal shielding at the sample position is provided through a removable thick aluminium tail with thin vanadium windows (see related images).
If you are planning to use a CCR please contact us well in advance, as we are willing to optimise the set up if there is a request.
|Other STFC||News||Site Sections||Important Links|