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Cryogenic cable

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)
	SC	SS
1 MHz	0.108	0.569
5 MHz	0.240	1.272
10 MHz	0.344	1.799
15 MHz	0.421	2.850
20 MHz	0.486	2.545
50 MHz	0.769	4.031
100 MHz	1.090	5.694
500 MHz	2.453	12.749
1 GHz	3.488	18.048
2 GHz	—	—
5 GHz	7.968	40.526

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

	4 K	20 K	30 K	77 K	300 K
RRR⁸ = 20	122	719	870	502	397
RRR = 100	460	2460	2070	533	407

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)
0.5	4.43 (1.35)	7.6
1.0	6.27 (1.91)	5.3
5.0	14.09 (4.30)	2.4
10.0	20.01 (6.10)	1.7
20.0	28.45 (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:

Score jacket
Bend at score until shield kinks, fatigues, and breaks
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

Field	Critical current (per wire)
3 T	35 A
5 T	25 A
7 T	15 A
9 T	6 A

	Temperature (K)
	295	77	4.2
Wire resistance (Ω/m)	9.2	8.4	0¹⁰
Overbraid resistance (Ω/m)	0.90	0.64	0.62
Thermal conductivity — entire cable assembly (W/(m•K))	7.6	2.8	0.17

¹⁰Superconducting