Focus On: Cryogenic Accessories

If you’re considering a Lake Shore purchase, have you thought about adding on some cryogenic accessories? Below we have summarised the benefits and advantages of the Lake Shore cryogenic accessories range and some interesting further reading.

Contents:

• Cryogenic Wire
• Separation of Quad-Lead Wires
• Cryogenic Cable Comparisons
• Miscellaneous Cryogenic Accessories

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Cryogenic Wire

Used to minimise heat leak into the sensor and cryogenic system, cryogenic wire has a much lower thermal conductivity (and higher electrical resistivity) than copper wire. The most common type of cryogenic wire is phosphor bronze. This wire is available in one-, two-, and four-lead configurations.

Four-lead configurations are available as Quad-twist™ (two twisted pairs) or Quad-lead™ (ribbon). Wire gauge is 32 or 36 AWG, with polyimide or polyvinyl formal (Formvar®) used to insulate the wires. Other wire types available include non-ferromagnetic manganin, nichrome heater wire, and 30 AWG heavy duty copper wire for heater leads.

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Separation of Quad-Lead™ Wires

Quad-Lead™ wires are formed into a “ribbon cable” using Bond Coat 999 bonding film. This bonding agent will soften above 160 to 180 °C. Individual wires can be separated either by heat or with a rotary-abrasion style mechanical stripper.

Download our how-to guide here:

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Cryogenic Cable

For high-frequency signals, Lake Shore provides various coaxial cables: ultra-miniature coaxial cables and semi-rigid coaxial with a stainless steel centre conductor.

At a glance:

Ultra miniature coaxial cable – Type C, SC, SS

Ultra miniature coaxial cable is for use when a strong and flexible cable is needed. Type C and SC are recommended when low conductor resistance is a prime consideration. Type SC and type SS are mechanically the most flexible, due to their braided construction. Type SS is recommended for use when both shielding and low thermal losses are important.

• Very flexible
• Long flex life
• Available in three configurations:
  
  C – solid copper centre conductor, drain wire, an aluminised/polyester shield
  SC – stranded copper conductors
  SS – stranded 304 stainless steel conductors

Semi-rigid coaxial cable—type SR

This cable transmits and receives high-speed, high-frequency microwave signals. Typically used for transmission lines in cryogenic-vacuum test systems.

• Easily bent, coiled, stripped, machined, soldered, or connected without impairing performance
• Solid centre conductor provides the optimum geometrical surface for transmission
• Low standing wave ratio (SWR) with a dielectric controlled to exacting tolerances
• Low thermal conductivity (≈0.4 W/(m·K) at 4.2 K)9
• Matching minimises reflective power loss
• Provides shielding isolation for virtually no extraneous signal pickup
• Tubular outer conductor offers minimum size and maximum conductor integrity; stainless steel jacket can be soldered directly to circuit boards
• 37 AWG, silver-plated copper-weld steel centre conductor

CryoCable™—type CYRC

A robust, 4-wire cable for use in cryogenic environments to room temperature is now available. The cable is designed around 32 AWG (203 µm) diameter superconductive wires consisting of a NbTi core (128 µm diameter) and a Cu-10% Ni jacket.

• Robust: the NbTi wire cores are strong and fatigue resistant, and the cable overbraid of 304 stainless steel adds significant strength and crush resistance
• Low heat leak due to all metal alloy and Teflon® construction
• Solderable: the CuNi wire surface is easy to solder with conventional rosin fluxes
• Cryo-compatible: all Teflon® (PFA) insulation is heat strippable for ease of preparation

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Other Cryogenic Accessories

Epoxy, grease, solder, cartridge heaters and vacuum feedthrough products are also available.