Boundraith: Kapitza Resistance
Thermodynamics & Statistical Physics arc, page 72 of 193. Back to The Pixelated Physics Universe
Who they are
Boundraith has one line, and says it often: “Even heat hesitates at the boundary.”
Boundraith is a character of the Thermodynamics & Statistical Physics arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Kapitza resistance: heat crossing a solid–liquid-helium boundary meets a thermal boundary resistance RK ∝ T⁻³ (acoustic mismatch).
$$ \begin{gathered} R_K \propto T^{-3} \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $R_K$ | Kapitza (thermal boundary) resistance | K·m^2/W |
| $T$ | temperature | K |
Sources
- P. L. Kapitza, J. Phys. USSR 4, 181 (1941)
- G. L. Pollack, Rev. Mod. Phys. 41, 48 (1969)
Crossovers
Boundraith meets Cryoselle (Dilution Fridge Qubit). Cryoselle must cool her sample through boundaries, and Boundraith guards every one. Kapitza resistance grows as the temperature falls, so cryogenic designers use sintered silver to multiply the contact area.
Boundraith meets Thermican (Bolometer Time Constant). Thermican's bolometer needs a weak thermal link G to its bath. Boundraith's boundary resistance is one of the things that sets that link at millikelvin temperatures.
Wear the lore
Concept keywords: Kapitza Resistance, Boundraith, Thermodynamics & Statistical Physics, physics lore, Pixelated Physics