The final cool-down

[RV]

No nejsem takovej anglictinar abych to prelozil uplne 100%ne, ale spis 
slo o to, aby to helium chladilo musi se odparovat ne? Samotne kapalne 
helium nic nechladi a jak je tedy udelany ten vlastni obvod chlazeni - 
jestli si to mam pradstavit jako obri cernackou feldflasku s filcovym 
obalem na magnetech a to odpareny helium se nekde jima a znovu zkapalni 
a vrati do okruhu?

Radek Vicek

Daniel Valuch napsal(a):
> specialista na tieto veci nie som, ale pisu ze:
> The superconducting magnet windings in arcs, dispersion suppressors and 
> inner triplets will be immersed in a pressurised bath of superfluid 
> helium at about 0.13 MPa (1.3 bar) and a maximum temperature of 1.9 K
> [7, 8]. This allows a sufficient temperature margin for heat transfer 
> across the electrical insulation. As the specific heat of the 
> superconducting alloy and its copper matrix fall rapidly with decreasing 
> temperature, the full benefit in terms of stability margin of operation 
> at 1.9 K instead of at the conventional 4.5 K may only be reaped by 
> making effective use of the transport properties of superfluid helium, 
> for which the temperature of 1.9 K also corresponds to a maximum in the 
> effective thermal conductivity [9]. The low bulk viscosity enables the 
> coolant to permeate the heart of the magnet windings, while the very 
> large specific heat (typically 105 times that of the conductor per unit 
> mass, 2 × 103 times per unit volume), combined with the enormous heat 
> conductivity at moderate flux (3000 times that of cryogenic-grade OFHC 
> copper, peaking at 1.9 K) can have a powerful stabilising action on 
> thermal disturbances.
> 
> 
> konkretne stavy a detailne informacie sa daju najst v design reporte 
> https://edms.cern.ch/file/445856/5/Vol_1_Chapter_11.pdf
> na strane 5 je termodynamicky diagram s teplotami a tlakmi.
> Udrzanie teploty chladiacej kvapaliny je dosiahnute dokonalou tepelnou 
> izolaciou od vonkajsich zdrojov tepla. Nicim inym.
> b.