The Kapitza Conductance of the (100) Surface of Copper and Polycrystalline Indium and Niobium.
Final rept. 15 Apr 71-14 Oct 74,
NATIONAL BUREAU OF STANDARDS BOULDER COLO CRYOGENICS DIV
Pagination or Media Count:
Measurements of the Kapitza conductance to liquid helium II across the 100 surface of single crystals of copper are presented. The sample surfaces were subjected to several different treatments. Some surfaces were cleaned by low energy argon ion bombardment, annealed in an ultrahigh vacuum system, and preserved under vacuum until purified liquid helium was admitted. Other surfaces were intentionally damaged by machining andor exposure to the atmosphere. Indications are that the effects on the conductance are produced primarily by the last few atomic layers of the solid, so extensive cold-working, which impairs the thermal conductivity of the bulk, need not be undertaken to improve surface heat transfer. This finding has important implications for the design of practical heat transfer surfaces. Conductance measurements of polycrystalline niobium and indium are presented in the appendices.
- Solid State Physics