Cryoprobe
From NMR Wiki
Cryoprobe or Cold probe is a technology where the probe coil and/or built-in signal preamplifier are cooled with a stream of He gas at ~20K. This increases the sensitivity of the probe coil and reduces the level of thermal noise generated by electronic circuits and components of the signal receiver itself.
The result is that the signal to noise ratio can increase by about 4X vs. a room temperature probe. In principle experiments can be run in 1/16 the amount of time as on a conventional probe, all else being equal. Or experiments can be run on samples with 1/4 the concentration in the same amount of time as on a conventional probe.
Typical parts included in the cryo-probe system
- Main cooling system - contains a coldhead which cools the helium gas to ~10K
- Helium compressor (provides highly compressed, room temperature helium gas)
- Cooling system for the compressor (compressor can be either air-cooled or water-cooled)
- Cylinder of grade 6 helium gas
- Cryoprobe - electronics are bathed in ~20K helium gas
Maintenance
Cryoprobes require periodic maintenance and careful operation.
For example, care must be taken so that water, cooling the He compressor is at suggested temperature (or even slightly cooler). Even if water temperature is only slightly above nominal, the compressor oil may overheat and start breaking down, and generating gases that will condense at cryogenic temperatures inside the system. This may lead to breakage of mechanical parts.
Gas filters (removing contaminants from He) need periodic replacement.
Expenses
- ~12,000 or more
