Development of Cryocoolers

Cryocoolers like domestic refrigerator require only electricity to produce low temperature. Cryocoolers developed at RRCAT are based on Gifford McMahon Cycle. They produce 30K in a single-stage cryocooler and 10K in a two-stage cryocooler. The entire cryocooler is made of indigenously available components.

The Cryocooler consist of two parts, an expander module and a compressor module. The Cryocooler uses Helium gas as working fluid. Helium gas during compression produces large amount of heat, therefore conventional compressors available in the market can not be used. Compressor for use in the above cryocooler has been developed at RRCAT by modification of conventional compressors, used in air conditioners, along with an on−line oil removal system.

Cryocoolers developed by us are being used by different user labs at RRCAT. These cryocoolers are being used with following setups:

1. Materials, Advanced Accelerator Science Div.:Working over a wide temperature range (30-400K), capable of precision measurements of phase transition phenomenon in magnetic materials and superconductors.


2. Semiconductor Laser Section: Temperature Dependent Electrical Transport measurements on semiconductors thin films and optoelectronic structures like lasers, detectors – Regularly grown using MOVPE system at RRCAT.


3. Laser Physics Applications Division: Temperature Dependent Carrier Dynamics measurements by Ultra Fast Pump Probe Spectroscopy.


4. Photoluminescence setup at BARC Spectroscopy Lab RRCAT Indore: Cryocooler is coupled to a specrofluorometer of Jobin-Vyon (Model no- Fluoromax-3) suitable for experiments in Temperature range of 40 to 300K.


5. Laser Physics Applications Division: Temperature Dependent Transient Photoconductivity & Photoluminescence of Organic Semiconductors.


6. Materials, Advanced Accelerator Science Div.: Resistivity versus Temperature measurements.

At such low temperatures (10K) most of the gases condense, this property is used to produce ultra-clean vacuum using cryocooler operated cryopumps. RRCAT has also developed a proto type cryopump with a pumping speed of 1,200 liters/sec, producing an ultimate vacuum of 10⁻⁸ mbar using 2-stage G-M Cryocooler developed by us.

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