The final cool-down

[Daniel Valuch]

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.



RV wrote:
> Kolega, kteremu obcas tyhle veci preposilam vznesl dotazy.
> 
> Jakým způsobem se zkapalňuje helium? Při jakým tlaku kapalnýho He tyhle 
> věci fungujou (Například NMR a podobně) aby to chladilo a přitom se to 
> hned nevypařilo? Jakej je princip vlastníhu udržení teploty toho helia v 
> okruhu magnetu?
> 
> Radek Vicek
> 
> Daniel Valuch napsal(a):
>> pokial je to v strede "arc magnets" tak to moze byt aj vadny senzor :-) 
>> Pokial ma ale inu farbu tak su to ine zatriadenia ktore su nainstalovane 
>> v serii, ale zatial sa nechladia. Napriklad nase supravodive 
>> urychlovacie dutiny su napajane heliom z magnetov, ale ventily sa 
>> otvoria az ked bude cely sektor vychladeny a stabilny (3-4, 4-5).
> ...
> 
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