Heat Transfer above Liquid Helium Surface in Cryostat

Heat-balance Integral Method for Heat Transfer in Superfluid Helium

The heat-bal ance in te gral method is used to solve the non-lin ear heat dif fu sion equa tion in static tur bu lent superfluid he lium (He II). Al though this is an ap prox i mate method, it has proven that it gives so lu tions with fairly good ac cu racy in non-lin ear fluid dy nam ics and heat trans fer. Us ing this method, it has been pos si ble to de velop pre dic tive so lu tions that re...

Heat Transfer by Impingement of Circular Free-Surface Liquid Jets

This paper reviews several aspects of liquid jet impingement cooling, focusing on research done in our lab at MIT. Free surface, circular liquid jet are considered. Theoretical and experimental results for the laminar stagnation zone are summarized. Turbulence effects are discussed, including correlations for the stagnation zone Nusselt number. Analytical results for downstream heat transfer in...

MgB2 HEB Mixers at Operation Temperatures above Liquid Helium Temperature

In this paper we discuss results of MgB2 thin films deposition for the hot-electron bolometer (HEB) application. For this purpose a custom made hybrid physical-chemical vapour deposition (HPCVD) system was built. For films thicknesses d in the 15-45nm range the critical temperatures were from 34K to 40K. For bridges as narrow as 500nm the critical current density was >107A/cm2 indicating a high...

Neutron reflection from the liquid helium surface

Helium cryostat for experimental study of natural turbulent convection.

Published experiments on natural turbulent convection in cryogenic (4)He gas show contradictory results in the values of Rayleigh number (Ra) higher than 10(11). This paper describes a new helium cryostat with a cylindrical cell designed for the study of the dependence of the Nusselt number (Nu) on the Rayleigh number (up to Ra approximately 10(15)) in order to help resolve the existing controv...