Cryogenic Solutions and IR Instruments for Research
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Closed Cycle Dewars
Closed Cycle Dewars & Refrigerators
Our closed cycle systems provide 300 to 4 K cooling and use the latest technology in Gifford- McMahon and Pulse Tube coolers, along with proprietary; low-vibration coupling to ensure your instruments will reach operating temperature without being subjected to the vibrations normally associated with closed cycle coolers.

Helium 3 Refrigerator

Our He3 closed cycle refrigerator is a unique instrument that is capable of cooling sensitive infrared and millimeter wave bolometers to 300 mK. The system utilizes the properties of He3, a man-made isotope of helium, in order to reach these temperatures. The system first condenses a few liters (STP) of He3. Condensation occurs at 2K. The vapor pressure of the LHe3 bath is then lowered by an absorption pump in order to drop the temperature down to a sustained operating point of 300 mK.

The He3 refrigerator is a multistage cooling device. An outer radiation shield is cooled to 77K by LN2. The condensing unit and absorption pump are cooled to below 2K by pumped LHe4. Once condensation occurs, a manually operated heat switch is opened in order to isolate the small LHe3 vessel from the LHe4 bath. A second heat switch is then closed in order to activate the absorption pump. Temperatures are sustained until the supply of He3 is consumed. Depending on design requirements, the cycle is easily repeated on 24 to 48 hour periods. Once condensation is accomplished, the system may be returned to 4.2 K.

The system contains no electrical or mechanical pumps. The only mechanical devices are the heat switches. This means that the system is rugged and portable and is ideally suited for use in laboratory, air borne, and balloon applications.

 Helium 3 Refrigerator (H3R Series)
  • Operating temperature of 0.29K to 0.35K
  • Closed cycle/portable
  • Operation
  • 24 to 48 hour hold Time
  • 0.30K bolometers available
  • Designed to customer specification
  • More...

Mechanical Closed Cycle Refrigerators
Our mechanical refrigerators are based on CTI-Cryogenics two stage closed cycle helium refrigeration systems. These systems are useful in applications where LN2 and LHe are either impractical or unavailable. First stage temperatures of 50K are typical. Second stage temperature can be as low as 10K. Because the coolers are closed cycle, these temperatures can be sustained indefinitely.

In order to make the refrigerators useful for scientific applications, we employ our own vibration isolation techniques to minimize the transfer of acoustic and low frequency vibration from the reciprocating engine. These techniques, along with our experience in cryogenic engineering and design, are applied to each application we design and build using a mechanical refrigerator.


JT Refrigerator
  • Operating temperature range 70K to 293K
  • Closed cycle operation
  • Indefinite hold time does not require LN2 or LHe
  • Low vibration cold head
  • Designed to customer specifications
  • More...
GM Refrigerator
  • Operating temperature range 7K to 60K
  • Closed cycle operation
  • Indefinite hold time
  • Does not require LN2 or LHe
  • Vibration isolation System
  • Optional dewar carts with 360 degree rotation and support up to 1000lbs
  • Designed to customer specifications
  • More...