Cryogenic cable

Cryogenic cable


Cryogenic cable features

Lake Shore provides various coaxial cables for high-frequency signals: ultra-miniature coaxial cables and semi-rigid coaxial with a stainless steel center conductor. We also offer the robust CryoCable™.

Ultra-miniature coaxial cable — type SC and SS

  • Very flexible
  • Long flex life
  • Available in two configurations:
    • SC — stranded copper conductors
    • SS — stranded 304 stainless steel conductors

Ultra-miniature coaxial cable is used when a strong and flexible cable is needed. Type SC is 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. See the technical specifications for the SS, SC, and SR types.

 Nominal attenuation (dB/m)
SCSS
1 MHz0.1080.569
5 MHz0.2401.272
10 MHz0.3441.799
15 MHz0.4212.850
20 MHz0.4862.545
50 MHz0.7694.031
100 MHz1.0905.694
500 MHz2.45312.749
1 GHz3.48818.048
2 GHz
5 GHz7.96840.526

Thermal conductivity of copper units are W/(m • K)

 4 K20 K30 K77 K300 K
RRR8 = 20122719870502397
RRR = 10046024602070533407

8 RRR = Residual Resistance Ratio

Semi-rigid coaxial cable — type SR

  • Easily bent, coiled, stripped, machined, soldered, or connected without impairing performance
  • Solid center 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 minimizes 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 center conductor

9 Thermal conductivity at low temperatures is dominated by the copper cladding around the center conductor

Coaxial cable frequency response specifications
Frequency (GHz)Insertion loss dB/m (dB/ft)Power CW (20 °C, sea level, W)
0.54.43 (1.35)7.6
1.06.27 (1.91)5.3
5.014.09 (4.30)2.4
10.020.01 (6.10)1.7
20.028.45 (8.67)1.2

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

To remove the outer conductor:

  1. Score jacket
  2. Bend at score until shield kinks, fatigues, and breaks
  3. Slide off outer conductor

Extreme caution must be used in this process to avoid damage to the coax

CryoCable™ — type CRYC

  • Robust: the NbTi wire cores are strong and fatigue-resistant, and the cable overbraid of 304 stainless steel adds significant strength and is crush-resistant
  • 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

CryoCable™ is a robust, 4-wire cable for use in cryogenic environments to room temperature. 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.

Cryocable

Minimum bend radius: 15 mm (0.6 in)

Critical temperature: 9.8 K

Critical field: 10 T

FieldCritical current (per wire)
3 T35 A
5 T25 A
7 T15 A
9 T6 A
 Temperature (K)
295774.2
Wire resistance (Ω/m) 9.28.4010
Overbraid resistance (Ω/m) 0.900.640.62
Thermal conductivity — entire cable assembly (W/(m•K)) 7.62.80.17

10 Superconducting