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...

After discussion of other models for representing heat capacities, the volumetric model used in resolution of lanthanide Schottky contributions over the cryogenic range and a more recent single-parameter formula to represent the lattice heat capacity, to resolve excess heat capacity contributions, to extrapolate lattice heat capacity beyond the measured temperature regions, and to predict therm...

Understanding the heat load from an electron beam on a cold beam tube (liner) is an open issue of great interest for the cryogenic layout of superconducting insertion devices. COLDDIAG, a cold vacuum chamber for diagnostics was designed and built especially for this purpose. The instrumentation comprises temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyze...

As popular aluminum alloys, the 5xxx Al-Mg series, such as 5050 and 5052, etc., are widely used in applications such as automobile, pressure vessels, armor plate, and components for marine and cryogenic service. In this, as in all non-heat-treatable aluminum alloys, the weld metal zone is considered to be the weakest part of the joint and is the location of failure when the joint is loaded in t...

Double-aluminized kapton (DAK) is commonly used in multi-layer insulation blankets in cryogenic systems. NASA plans to use individual DAK sheets in lightweight deployable shields for satellites carrying instruments. A set of these shields will reflect away thermal radiation from the sun, the earth, and the instrument's warm side and allow the instrument's cold side to radiate its own heat to de...

Whereas thermoelectric performance is normally limited by the figure of merit ZT, transverse thermoelectrics can achieve arbitrarily large temperature differences in a single leg even with inferior ZT by being geometrically tapered. We introduce a band-engineered transverse thermoelectric with p-type Seebeck in one direction and n-type orthogonal, resulting in off-diagonal terms that drive heat...

The cold bore experiment (COLDEX) installed in the Super Proton Synchrotron (SPS) has been used to study the performance of a vacuum system operating at cryogenic temperatures in the presence of a Large Hadron Collider (LHC) type proton beam. The ~ 2 m long cryostat, which can be cooled below 3 K, is fitted with an actively cooled beam screen which can be temperature-controlled between 5 and 10...

Abstract Vanadis 6 cold work tool steel was vacuum austenitized, room temperature quenched, differently cryogenically treated (-75, -140 and -196 °C for different durations) double tempered, at temperatures of either 170 or 530 °C. Galling resistance assessed by pin-on-disc testing specimens against CuSn bronze, wide ranges sliding velocities loads. The obtained results show that cryogenic trea...

The article presents the mathematical models and the results obtained has the numerical modelling of the thermal status of the electrical leads isolated for cryogenic applications. Model them mathematics are based on the equation of thermal conduction 1D and 2D. For the numerical resolution of the thermal conduction equation one uses the finite volumes method. The elaborate program permits to g...