Mechanical losses cryogenics

Dielectric-loss tangents at cryogenic temperatures show the same temperature dependence as mechanical-loss tangents. However, they differ by a factor C, which ranges from 10 to 1 for nonpolar and polar polymers, respectively (11). 

Table I lists the mechanical properties of thermally hardened alloys of the duraluminum type (Al-Cu-Mg), as well as the Al-Zn-Mg-Cu alloys. A temperature decrease to 20 K increases the ultimate strength by 25 to 30%. The yield stress continuously increases as the temperature decreases. The relative elongation behaves in different ways in some alloys, it is practically constant, while in alloy V96 it is reduced by almost a factor of 5. Thus, hardening of alloys, such as V95 and V96, by thermal treatment produces materials with a sufficiently high level of strength, but losses in plasticity are inevitable. This is a significant limitation of their application in cryogenic equipment.

Cryogenic cold traps in Zone 2A. (Capture process radioactive noble gas in the vacuum system flow to control release.) Plugged trap or broken vacuum line Mechanical malfunction or worker error Control and monitoring system indications and periodic maintenance inspections Redundant cold traps provide multiple flow paths for vacuum. Loss of vacuum and potential release of noble gas. 

When using a condensible gas to overpressure a tank of cryogenic liquid, a gas diffuser or deflector is necessary to minimize turbulence of the liquid and subsequent excessive condensation losses. Our tests show that a significant increase in condensed mass results from a mechanical disturbance of the liquid surface. 

The maximum test frequencies for cryogenic fatigue measurements can be much higher than at RT because of very low mechanical damping (tan Sm < 10 at 4.2 K) and absence of rate dependence below 1 kHz. The heat power generated per sample volume V can be estimated from the loss tangent. Young s modulus E iT), strain amplitude e, and test frequency/ ... 

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