Design of LHC prototype dipole cryostats

Does one need a 4.5 K screen in cryostats of superconducting accelerator devices operating in superfluid helium? lessons from the LHL

“…Subsequently, the first generation of LHC prototype cryostats had no solid 4.5 K screen, but a blanket of 10 layers multilayer insulation (doublealuminized polyester film with spun-bonded polyester spacer) wrapped around the cold mass and tentatively thermalized to the 4.5 K pipes running through the cryostats. The heat inleak from the thermal shield was also reduced by cooling it with gaseous helium at 50-70 K instead of liquid nitrogen [13]. A full-scale thermal model, equipped with a dummy cold mass and heavily instrumented, confirmed the effectiveness of the multilayer system in degraded vacuum [14].…”

“…Left: TAP prototype (legend in ref [10]). Middle: first series prototypes (legend in ref [13]). Right: series cryostats.…”

Comparison of Floating and Thermalized Multilayer Insulation Systems at Low Boundary Temperature

“…Applying this model to a 15-m long LHC dipole cryostat, we can find the range of validity of values of R cp and r cm for which a thermalized system performs better than floating multilayer insulation. Figure 3 shows the break-even lines comparing with the 10-layer system of type B in reference [4], which presently equips the LHC prototype cryomagnets [6][7][8], assuming an emissivity of the soft screen of 0.05 in the 5 to 30 K range. The surface covered by the spacers has been considered equivalent to 25 % of the total cold mass area.…”

“…First results [4] confirmed the advantage of multilayer systems over single reflective surfaces for coping with degraded insulation vacuum, a situation bound to happen locally over the circumference of the machine, and further tests [5] sought to improve the performance of "floating" multilayer systems by limiting parasitic conduction between layers. Cryostats for prototype cryomagnets [6] and a full-size thermal model [7] were built in industry and operated with such an insulation system, bringing a real-scale verification of the thermal performance measured on samples and thus validating thermal budget estimates for the LHC [8]. In view of the importance of this source of heat inleak to the 1.9 K level, we investigate in the following the potential of improvement presented by an alternative combining multilayer reflective films and a soft screen, actively thermalized to the 5 K level and supported away from the cold wall by net-type insulating spacers.…”

Data Interlocking: Coupling Analytics to the Data

“…This sentiment was clearly presented by Prof. Clifford Lynch, Director of the Coalition for Network Information in 2008 [23]. Projects like CERN [24], Large Synoptic Survey Telescope [25] in northern Chile or the $1000 genome [26] are all endeavors with a demand on large scale data storage, management and maintenance. Cloud paradigm provides a solution for this need by supplying virtually infinite amount of storage to its users.…”