Cryocrystallography: Crystal Coolers
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BioCARS has the following crystal coolers:
- Oxford Cryosystems CryoStream
- Oxford Instrument CryoJet (old and new design)
- Home made liquid nitrogen/helium cooler
- FTS cooler for ambient temperatures
| Cooler | Temperature range (K) | Cold gas flow rate (l/min) | Nozzle size dia. (mm) |
|---|---|---|---|
| New Cryojet | 100 -300 | 4 - 10 | 7.2 |
| Old Cryojet | 100 - 300 | 4 - 6 | 7.2 |
| Cryostream | 100 - 300 | 5 | 5.0 |
| LN2/LHe | 20 - 200 | 10 -15 | 7.9 |
| FTS | 200 - 293> | 28 - 56 | 25.0 |
New Cryojet Cooler
New CryoJet Procedures (Staff only)
The new boil-off design CryoJet crystal cooler supplies cold nitrogen gas by evaporating liquid nitrogen with a heater at the end of CryoJet dewar leg. Cold boiled-off gas starts from the bottom of the Oxford 75 liter dewar. The Transfer Tube transports the gas to the heat exchanger in the ColdHead, where its temperature is regulated by the programmable ITC503 Cryojet controller. This design reduces the chance of ice blockage, which happens often in the pumped design coolers. The lowest reachable temperature however is higher than for the pumped design coolers. The warm gas shield at the nozzle is also supplied by a boiled-off gas line. It is important to keep the warm gas flow rate about the same as the cold gas flow rate (4 l/min).
Old Cryojet Cooler
Old CryoJet Procedures (Staff only)
The old pumped design CryoJet crystal cooler draws liquid nitrogen from an Oxford 50 liter dewar through a diaphragm pump ("Cryojet Pump") through the Transfer Tube to the heat exchanger in the ColdHead. There, the liquid is evaporated, then dried by the line drier and fed back to the ColdHead. The gas is re-cooled there and its temperature is controlled by the programmable temperature controller ITC502. The warm gas shield at the nozzle is supplied by the BioCARS cryostat nitrogen line. The flow rate of the warm gas can be adjusted on the Cryostat Gas panel in the hutch. It is important to keep this flow rate about the same as the cold gas flow rate (5 l/min).
Cryostream Cooler
Cryostream Procedures (Staff only)
The CryoStream crystal cooler draws liquid nitrogen from a Taylor Wharton 35DL dewar through the Diaphragm Pump and the Supply Line to the Heat Exchanger.
The liquid is evaporated in the Heat Exchanger, dried by the Line Drier and fed back to the ColdHead.
The gas is then recooled and its temperature controlled by the Programmable Temperature Controller via the Heater Coil.
The warm gas shield at the nozzle is supplied by the BioCARS cryostat nitrogen line. The flow rate of the warm gas can be adjusted on the Cryostat Gas panel in the hutch. It is important to keep the warm gas flow rate about the same as the cold gas flow rate (5 l/min).
LN2LHe Cooler
LHe/LN2 Procedures (Staff only)
BioCARS home made crystal cooler uses either liquid nitrogen or liquid helium as the cryogen. It is used on special user demand/collaboration only. See sketch bellow for its operational principle, for details refer to: Teng et al., Two open-flow cryostats for macromolecular crystallography, J. Appl. Cryst. (1994). 27, 133-139. Please visit the IUCr web site to download a pdf file or to buy a hard copy.
FTS Cooler
FTS Procedures (Staff only)
The FTS XR-85-1 Air-JetTM crystal cooler is based on the refrigeration of dry gas from compressed air. Its temperature range is from +20 to -70C. BioCARS wide-mouth nozzle (d ~ 1") provides a large volume of laminar flow (up to ~2 standard cubic feet per minute) adequate to maintain constant temperature around a capillary-mounted crystal at room temperature.
