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Temperatures below 300mK with 3Helium Refrigerators
The Heliox® range of 3He refrigerators enables temperatures below 300mK to be achieved. There are four models to choose from depending on your experiment requirements.
Mode of operation
3He, the lighter isotope of helium, condenses at a lower temperature (3.19K) than 4He (4.22K). By evaporating 3He and reducing its vapour pressure, temperatures below 300mK may be achieved.
- The activated charcoal sorb (a type of cryopump) is warmed to about 30K to de-sorb all 3He.
- Pumping on 4He to about 1.5K cools an independent cold stage or coil. This cools and condenses the entire charge of 3He gas, which collects as a liquid in the 3He pot.
- The sorb is then allowed to cool below 5K. 3He gas is then adsorbed and the pot is cooled by evaporation from the liquid towards a limit of about 260mK.
- Pumping continues until all the liquid 3He has been evaporated. It must then be re-condensed and re-cooled. This is known as “single shot” mode.
Heliox® systems have hold times of at least 24 - 60 hours and can be recharged in less than one hour so the interruption is minimal.
3He refrigerators are generally designed for operation in the temperature range 0.3 – 1.2K but there are options to extend the temperature range to higher temperatures.
Choose a Heliox system
The HelioxAC-V is a very compact Cryofree 3He system with sample environment in vacuum. It achieves a base temperature below 300mK for more than 50 hours.
The HelioxTL is a top-loading 3He system for an optimum turnaround time and sample environment in liquid 3He. It ensures good thermal contact between the sample and liquid 3He and high stability of the thermal environment.
The HelioxVL is a very compact 3He system which provides cost-effective access and may be used in a 4He storage dewar.
The HelioxVT can be used inside any 30mm or 50 mm diameter 4He VTIs. As there is no liquid helium into the sample horizontal plane, this 3He refrigerator is ideal for Neutron or Xray scattering experiments.
Automation
A LabVIEWTM virtual instrument is available for the ITC503 to allow automation of temperature control.
Signals from the ITC503 are combined and displayed in a Heliox virtual instrument to simulate all standard Heliox functions; Condense, Set temperature and Warm up are thereby fully automated. This can be integrated into a complete data acquisition system.
Heliox Labview software
HelioxAC-V Cryogen-free 3He system
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