The dilution process. 4K flange. Still. Heat exchangers. Mixing chamber

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1 cryogenic systems

2 CRYOCONCEPT has been supplying dilution refrigerators since In partnership with the low temperature department of the CEA located in Saclay (France), our company adjusted and improved the designs with the requirements of physicists in mind. Dilution refrigerators from CRYOCONCEPT are used in a wide range of applications and experimental techniques: -Solid state physics at very low temperature: quantum computing, nanomagnetism, superconductivity -Low temperature detectors: Germanium detectors, sapphire detectors... CRYOCONCEPT has installed dilution refrigerators in many laboratories worldwide. We have built up expertise in low temperature physics to the benefit of the end user of reliable technologies in experimental wiring, sample positioning and environment noise reduction.

3 The dilution process The principle of the dilution refrigerator is based on the quantum properties of liquid mixtures of the two He isotopes ( 3 He and 4 He). When such a mixture is cooled to 0.86K it separates into two distinct phases: a concentrated 3 He phase and a diluted 3 He phase. The key point is that even at zero temperature the 3 He concentration in the diluted phase of the mixture is finite (6.4%). Below 0.5K, the superfluid 4 He of the diluted phase is in a fundamental state with a negligible entropy. For that reason, 4 He behave as a «vacuum». 4K flange Still Heat exchangers Mixing chamber In the mixing chamber, the lighter concentrated phase forms above the diluted phase. A cooling effect is created by 3 He atoms passing from the concentrated phase to the diluted phase. This cooling effect can be viewed as an evaporation of 3 He. Without heat addition from outside, this process will cause cooling of the two phases in the mixing chamber. The solubility limit (6.4%) allows passage of the 3 He atoms into the dilute phase even at the lowest temperatures, thus mantaining a large cooling power. The 3 He atoms are extracted by pumping on the still at a temperature a little below 1 K. The dilution process runs in a closed cycle. Before being re-introduced into the cryostat, the evaporated 3 He is cooled down to 4.2K in a liquid helium Dewar. Then the 3 He is liquefied: Refrigerators from CRYOCONCEPT include a Joule Thomson stage which replaces the usual 4 He pot and external pumping system. 200µW dilution part Finally the liquid 3 He is cooled at the still and in the heat exchangers before again reaching the mixing chamber.

4 DR-JT-S Base temperature guaranteed less than 30 mk Cooling power at 100mK guaranteed greater than 30µW Typical dimensions Outer diameter of the insert: between 68 mm and 75 mm Total length of the insert with IVC: up to 2500 mm Sample space at low temperature (dependent on Dewar and magnet): from 35 mm to 40 mm in diameter up to 300 mm in length Special Features of CRYOCONCEPT design Joule Thomson exchanger (replacing the separate pumped bath condenser) easily removable IVC (third clamps and indium seal) Radiation shields and IVC can be designed to fit into magnet Experimental curves Temperature measurements made with TRMC2 controller and RuO 2 thermometer calibrated by Nuclear Orientation. Thermometer is located in vacuum on the mixing chamber plate.

5 DR-JT-S Pictures 1, 2: Dilution refrigerator provided with 28 coaxial cables for audio frequency measurements. Hermetic SMA connectors at room temperature, Heat sinks for coaxial cables at 100mK and a special connector at 30mK Pictures 3, 4: Dilution refrigerator provided with 3 access lines to the Inner Vacuum Can with NW16 port at room temperature and 3 line of sight access ports from room temperature to the mixing chamber. Customer specified plastic mixing chamber for use in high magnetic fields. Picture 5: 30µW Gas Handling System with 18m 3 /h rotary vane pump and compressor.

6 DR-JT-S Base temperature guaranteed less than 10 mk Cooling power at 100mK guaranteed greater than 100µW Typical dimensions Outer diameter of the insert: 110 mm Total length of the insert with IVC: up to 2500 mm Approximate sample space at low temperature (depends on Dewar and magnet): from 40 mm to 80 mm in diameter up to 300 mm in length Special Features of CRYOCONCEPT design Joule Thomson exchanger (replacing a separate pumped bath condenser) Easily removable IVC (Third clamps and indium seal) Radiation shields and IVC could be designed to fit into magnet Can be provided with additional 1K pot for thermalisation of wiring or measurement devices Experimental curves Temperature measurements made with TRMC2 controller and RuO 2 thermometer calibrated by Nuclear Orientation. Thermometer is located in vacuum on the mixing chamber plate.

7 DR-JT-S Picture 1: 300K flange with 6 hermetic SMA connectors for coaxial cables. Pictures 2, 3: Dilution refrigerator provided with additional 1K pot and special heat sinks for stainless twisted pair wires and superconductive wires. Used for SQUID applications. Picture 4: Special wiring to customer specification: manganin wires and coaxial cable with SMA connector Picture 5: 100µW insert with special Inner Vacuum Can to fit superconducting magnet. 9 Picture 6: 300K flange equipped with 3 access lines through liquid helium, used for installation of flexible and low impedance wires like copper wires or capillary tubes. 10 Picture 7: Easily removable clamps for indium seal of Inner Vacuum Can. Picture 8: Control panel of the Gas Handling System displays pressures and allows manual or automatic condensation process. Picture 9: 100µW Gas Handling System with 20m 3 /hr rotary vane pump, 250l/s turbomolecular pump and compressor. Picture 10: Sample rotator mounted on the mixing chamber and driven by a room temperature DC motor.

8 DR-JT-S Base temperature guaranteed less than 10 mk Cooling power at 100mK guaranteed greater than 200µW Typical dimensions Outer diameter of the insert: 180 mm Total length of the insert with IVC: up to 2500 mm Approximate sample space at low temperature (depends on Dewar and magnet) 140 mm in diameter until 400 mm in length Special Features of CRYOCONCEPT design Joule Thomson exchanger (replace a separate pumped bath condenser) easily removable IVC (Third clamps and indium seal) exchangeable connector plates on experimental lines Radiation shields and IVC can be designed to fit into magnet Can be provided with additional 1K pot for thermalisation of wiring or measurement devices Experimental curves Temperature measurements made with TRMC2 controller and RuO 2 thermometer calibrated by Nuclear Orientation. Thermometer is located in vacuum on the mixing chamber plate.

9 DR-JT-S Pictures 1, 2: Dilution refrigerator provided with: 2 line of sight ports from room temperature to the mixing chamber (31 mm to 38 mm dia.), 3 access lines through liquid helium from room temperature to the mixing chamber (31 mm to 38 mm dia.), 1 access line from room temperature to IVC (7 mm in dia.) and 4 spare ports at room temperature. Each line has corresponding cutouts in the plates of the dilution refrigerator Picture 3: Bottom side of the 4K plate with copper heat sinks. Picture 4: 38 mm lines for wiring through liquid helium. Picture 5: Bottom side of the 6 mixing chamber plate with RuO 2 thermometers and customer specified connector. 2 Picture 6: 180 mm OD IVC with easily removable clamps and a copper radiation shield around the sample space.

10 DR-JT-S CRYOCONCEPT provides Gas Handling Systems safely controlled by a programmable controller installed inside the control panel. This unit can be placed in the laboratory remote from the vacuum pumps. The dilution refrigerator can be remote controlled by computer through the Ethernet port of the programmable controller. 1 2 Picture 1: Gas handling system provided with a 600m 3 /hr ROOTS pump and a 40m 3 /hr rotary vane pump. Mixture injection is made at 4 bars via a compressor. Picture 2: Control panel of the 200µW GHS allows control of pumps and valves and monitoring of pressures. 3 Picture 3: Remote control panel installed on a computer. This software allows control of the Gas Handling System by communicating with real time software running on the programmable controller.

11 Liquid Helium Dewar CRYOCONCEPT provides liquid helium belly Dewars designed to receive 200µW dilution inserts and high field superconducting magnets. Dewars are constructed from 316L Stainless Steel and Aluminium. On customer request, CRYOCONCEPT can design special support systems for magnets located inside the Dewar tail. CRYOCONCEPT Dewars are liquid nitrogen free to prevent problems with the boiling of nitrogen. The careful design allows helium consumption below: 0.3 litres of liquid per hour. This technology offers roughly 5 days hold time. Usual dimensions Outer diameter of the Dewar: 550 mm Total length of the Dewar: up to 2200 mm Inside shape of the liquid helium belly Dewar

12 Reference customers Dr. KONO, RIKEN, Low Temperature Physics Lab, JAPAN Dr. MATSUDA, Institute for Solid State Physics, Tokyo, JAPAN Dr. KASHIWAYA, ETL Advanced Metrology Section, Metrology Fundamentals Division, JAPAN Dr. SHIRAHAMA, Keio University, Department of physics - Yokohama, JAPAN Dr. KAMBE, Advanced Science Research Center, JAERI, Tokai, JAPAN, Dr. MAENO, Associate Professor, Department of Mechanical Engineering, Keio University,Yokohama, JAPAN Dr. TAKEUCHI, Low Temperature Center, Osaka University, Osaka, JAPAN Dr. MACHIDA, Tokyo University, Tokyo, JAPAN Dr. KOGA, NTT Basic Research Laboratories, Nippon Telegraph and Telephone Corporation, Kanagawa, JAPAN Dr. KOMIYAMA, Department of Chemical System Engineering, School of Engineering, The University of Tokyo, Tokyo, JAPAN Prof. DEVORET, Yale University, Department of Applied Physics, New Heaven (CT), USA Prof. SCHOELKOPF, Yale University, Department of Applied Physics, New Heaven (CT), USA Prof. BARRETT, Yale University, New Heaven (CT), USA E.LEBLANC, DRT / LNHB / CEA, Saclay, FRANCE Dr. LEHNERT, University of Colorado, Boulder, Colorado, USA M. FELTIN, BNM, Trappes, France

13 Contacts For all countries except Japan : CRYOCONCEPT 4, avenue des Andes COURTABOEUF Cedex France Phone : +33 (0) Fax : +33 (0) contact@cryoconcept.fr Link to our Web page : Japan : NIKI GLASS Co., Ltd. Tokyo Office : Koji Nishi / Manager of Cryogenics 9-7 Mita 3-Chome Minato-ku Tokyo Japan Phone: Fax: nishi@nikiglass.com Osaka Office : Koichi Nishio / Manager of Osaka office 2-16 Nishi-Nakajima 6-Chome Yodogawa-ku Osaka Japan Phone : Fax : nishio@nikiglass.com Link to our Web page : (English) (Japanese)