Cryogenic Semi-Rigid RF Cable Assemblies

Overview
Amphenol Military & Aerospace supplies CryoCoax semi‑rigid RF cable assemblies through its IntelliConnect division to support quantum computing, space science, and low‑temperature instrumentation. Each assembly delivers stable 50 Ω coaxial transmission and mechanical integrity under extreme thermal contraction encountered below 4 K.

Material and Construction Options
The assemblies are offered in 0.034 in, 0.047 in, and 0.085 in diameters with multiple conductor materials selected for specific thermal and electrical trade‑offs:

• Stainless Steel – Higher attenuation and low thermal conductivity, ideal for input or drive lines where attenuation reduces noise at the qubit stage.
• Cupronickel (CuNi) – Balanced attenuation and conductivity for intermediate temperature stages.
• Niobium‑Titanium (NbTi) – Superconducting below 10 K with very low insertion loss between the 4 K and mixing‑chamber levels.
• Beryllium‑Copper (BeCu) – High conductivity and durability for mechanical transitions and feedthroughs.

Electrical and Mechanical Performance
Standard configurations operate from DC to 40 GHz, with performance available to 50 GHz for superconducting variants. The semi‑rigid metal sheath ensures dimensional and impedance stability with a small minimum bend radius and strong electromagnetic shielding. All lines are electrically tested for DC resistance, return loss, and insertion loss.

Connector Interfaces and Integration
Assemblies can be terminated with SMA, 2.92 mm, or SMP interfaces, as well as specialized CryoCoax Q‑CON high‑density connectors for multi‑line quantum wiring. Solderless attachment methods are available for NbTi cables that cannot be traditionally soldered. Non‑magnetic connector versions are optional for sensitive magnetic environments.

System Applications
CryoCoax semi‑rigid assemblies are used in dilution refrigerators, cryogenic test chambers, superconducting quantum devices, MRI systems, and low‑temperature aerospace sensors. They may be combined into complete coax‑stick assemblies with custom attenuators and stage‑by‑stage materials, providing continuous connections from room temperature to the mixing chamber.

Selection Guidance
Engineers can select conductor material according to temperature stage and desired attenuation characteristics, and choose connector type based on integration density or thermal anchor layout. 100 % electrical testing before dispatch ensures verified impedance and performance consistency.