Estimate static conductive heat loads from multi-port coax lines across dilution-refrigerator stages (300 K → mK), calibrated against published measurements — built for quantum computing wiring design.
Wiring Configuration
Set how many lines run through the fridge and which Rosenberger connector family they use. Cable size scales the load with conductor cross-section — thinner coax conducts less heat.
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The connector itself is a negligible thermal path compared to the coax conductors.
Scales load by conductor cross-section, ≈ (OD ratio)².
Stage Geometry & Material
Pick a preset scheme, or set each segment’s length and material. Longer segments and lower-conductivity materials carry less heat. NbTi is offered only below the 4 K stage.per segment, RT → MXC
NbTi is only offered below the 4 K stage — above its ≈9.8 K critical temperature it carries no superconducting advantage and behaves as a poor normal-metal conductor with no measured reference data here.
Stage Stack
A picture of the heat flowing down your wiring, RT to the mixing chamber, with each stage’s load. Use it to spot the biggest contributor.heat flow, RT → MXC
Available Cooling Power
The cooling power of each stage of your fridge. Defaults are published Bluefors-class figures — replace them with your cryostat’s datasheet values.edit to match your fridge
Defaults are the published figures for a Bluefors-class wet/dry DR (Krinner et al., 2019) — replace with your cryostat's datasheet numbers for an accurate margin check.
Active RF Dissipation
Optional. Add attenuators or other parts anchored at a stage that carry live RF power. Each dissipates Pin·(1 − 10−dB/10) at its stage. Leave empty if none.optional — attenuators, isolators, amps thermally anchored at a stage
A thermally-anchored attenuator dissipates Pin·(1 − 10^(−dB/10)) as heat at its stage. Pulled straight from our RF Attenuator Calculator — use it to size the pad, then add the same dB/power here to see its contribution to that stage's budget. Rosenberger also offers ceramic attenuator elements integrated directly into multichannel connectors — ask your rep if in-connector attenuation fits your build.
Estimated Heat Loads
Each stage’s total load (conducted + RF) as a share of its cooling power: OK below 50%, Watch from 50%, Over budget from 85%.
Notes & Sources
Static conductive loads only — Fourier's law, scaled from measured reference values (not active I²R/RF dissipation from the line itself, and not blackbody radiation through apertures, both of which are normally small next to conduction for coax but should be checked separately for open apertures or high-power lines). Published measurement uncertainty on these figures runs ≈30–50%; keep margin below 100% of budget, and validate against your own cable vendor's κ(T) data or a direct measurement for mission-critical designs.
Calibration references:
• S. Krinner et al., "Engineering cryogenic setups for 100-qubit scale superconducting circuit systems," EPJ Quantum Technology 6, 2 (2019) — measured per-line static heat loads for UT‑085 stainless-steel and NbTi coax across RT→50 K→4 K→Still→CP→MXC, used here as the Stainless Steel reference.
• A. Kushino et al., "Thermal Conductance and High-Frequency Properties of Cryogenic... Semi-rigid Coaxial Cables," J. Low Temp. Phys. (2018) — relative conductance of SS304 : CuNi : BeCu semi-rigid coax (≈1 : 2 : 4 below 8 K), used to scale the CuNi and BeCu options.
All four materials above — stainless steel, CuNi, BeCu, and NbTi — plus non-magnetic (AuroDur®-plated) hardware, hermetic glass-to-metal feedthroughs, and superconducting cable assemblies are available from Rosenberger's own Cryogenic & Quantum Technology line, including the Multichannel WSMP interconnect developed for quantum computing under the German-funded qBriqs program.