Cryostats

Entropy provides closed-cycle cryostats based on 1- and 2-stage GM or pulse-tube coolers for continuous operation at low temperatures.

• Various temperature ranges with different cooling power
• GM cooler for 70K, 50K and 10K
• Pulse-tube cooler for temperatures < 3K
• Variable sample space available
  • Ø 180 x 200mm (S-series)
  • Ø 230 x 300mm (M-series)
  • Ø 300 x 300mm (L-series)
  • Or completely custom-made
• Vibration isolation by copper braids and bellows
• Sample magnets on request
• Fully featured setup with temperature sensors and heaters
• Electronics and software
• TCP/IP interface for remote control
• Fully assembled and tested or as a cryostat kit for assembly by the client

Joule-Thomson Cryostats (JT)

The Entropy cryostat with Joule-Thomson stage offers continuous operation at temperatures around 1K and a cooling power of a few Milliwatt.

Entropy JT cryostats are available as M- and L-series based on pulse-tube coolers with a cooling power of 0.5W or 1.0W at 4.2K and various sample space.

JT stage with turbo pump:

• Base temperature: < 0.9K
• Cooling power: a few mW at 1.0K

JT stage with fore pump only:

• Base temperature: < 1.2K
• Cooling power: a few mW at 1.3K

Sample space at 4K:

• Ø 230 x 300mm (M-series)
• Ø 300 x 300mm (L-series)
• Or completely custom-made

Application example:

Cryostat for operating 64 Superconducting Single Photon Detectors (SSPDs) below 1K.

The systems come fully featured up with temperature sensors, heaters, electronics and software with TCP/IP interface for remote control.

Several accessories such as DC cables, coax cables, circuit boards, fibers, optical ports and sample magnets are available on request.

Cryostats with Sorption Unit

The Entropy cryostats with sorption units are available as M- and L-series based on pulse-tube coolers with a cooling power of 0.5W or 1.0W at 4.2K and various sample space.

We offer the cryostats with He-4 and He-7 sorption units from our partner Chase Research Cryogenics LTD.

Cryostat with He-4 Unit:

• Base temperature: < 1K
• Hold time: > 12 hours @ 1K with 100µW heat load

Cryostat with He-7 Unit:

• Base temperature: < 300mK
• Hold time: > 24 hours @ 300mK with 20/50µW heat load

Sample space at 4K:

• Ø 230 x 300mm (M-series)
• Ø 300 x 300mm (L-series)
• Or completely custom-made

The systems come fully featured up with temperature sensors, heaters, electronics and software with TCP/IP interface for remote control.

Several accessories such as DC cables, coax cables, circuit boards, fibers, optical ports and sample magnets are available on request.

Adiabatic Demagnetization Refrigerator (ADR)

Our ADRs offer a fast and reliable way to get into the Millikelvin range. Optimized for easy access and handling.

The Entropy ADR cryostats are available as M- and L-series based on pulse-tube coolers with a cooling power of 0.5W or 1.0W at 4.2K and various sample space.

The ADR stage consists of a superconducting magnet, a double-stage salt pill unit and a heat switch.

Base temperature: 30mK

Cooling capacity: 150mJ @ 100mK, 1.8J @ 1K

Hold time: more than 48 hours @ 100mK

Recharge time: 1 hour

Sample space at 4K:

• Ø 230 x 300mm (M-series)
• Ø 300 x 300mm (L-series)
• Or completely custom-made

The systems come fully featured up with temperature sensors, heaters, electronics and software with TCP/IP interface for remote control.

Several accessories such as DC cables, coax cables, circuit boards, fibers, optical ports and sample magnets are available on request.

Dilution Refrigerator

Cold Optical Box (COBox)

The COBox is a unique solution from Entropy for vibration-sensitive experiments at low temperatures. For maximal vibration isolation the COBox is connected rigidly to your optical table and only flexibly to the coldest stage of the cryostat.

The COBox is available in combination with:

• Pulse-tube cooler only for temperatures < 3K
• Joule-Thomson cryostats for temperatures around 1K
• Dilution refrigerators for temperatures < 50mK

RuOx Sensors

Thick-film chip resistors based on Ruthenium Oxide are effective low-temperature thermometers.

Entropy offers several types of RuOx sensors for different temperature ranges and applications in high magnetic field.

Housing: The standard sensor housing is made of pure silver or copper. A minimal amount of pure epoxy is used in the construction to avoid heat-capacity anomalies from epoxy fillers. The sensor has an integrated SMD connector for easy and reliable electrical connection.

Other housing options such as chips on silver foil or naked are available on request.

RuOx Type A

• Useful down to 200mK
• Individually calibrated
• Typical resistance: 100kΩ at 200mK

RuOx Type B

• Useful down to 20mK
• Individual or batch calibration available
• Typical resistance: 10kΩ at 100mK

RuOx Type C

• Very small magneto-resistance
• Individually calibrated
• Useful down to 50mK
• Typical resistance: 100kΩ at 100mK

RuOx Type D

• Useful down to < 30mK
• Individually calibrated
• Typical resistance: 15kΩ at 100mK

             Typical Resistance Values

                Typical Sensitivity Values

         Typical Dimensionless Sensitivity Values

RuOx Type Z

• Customized sensor
• Individually calibrated

Ask us for a tailored solution for your application.

Accessories

Circuit boards, cables, copper braids

Circuit boards

• Connector boards with Micro-D, LEMO and SMD for DC wiring
• ‚Plug and Play‘ solutions for SQUID wiring and thermometry

DC Cables

• Manganin
• Copper
• Phosphor Bronze
• NbTi/CuNi

Copper braids

Flexible, thermal links made of single copper wires with 50µm diameter for cryogenic application.