Towards cryogel®Z and glass spheres insulated cryostats for superconducting detector solenoids: R&D in the frame of the 2014-2020 future circular collider study at CERN

Veronica Ilardi

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Abstract

In the frame of the Future Circular Collider (FCC) study, the FCC-ee+ IDEA detector magnet comprises a solenoid installed around the inner tracker directly, thus inside the dual-readout calorimeter, saving about a factor 4 in stored magnetic energy and roughly a factor 2 in cost. The radiation thickness of the solenoid must then be minimized to allow the particles emanated from the interaction point to reach the calorimeter. The concept can eventually be adapted for the longer-term FCC-hh. This thesis work constitutes a feasibility study of a cryostat concept for this “ultra-thin” detector solenoid.
The 20 mm thick uniform plate that constitutes the cryostat’s outer vessel wall is here replaced by an aluminum foil of some 100 μm thickness. The thin foil must ensure vacuum tightness but is not required to withstand the atmospheric pressure, nor the weight of the cold mass. Instead, the typical multi-layer insulation (MLI) is replaced by an insulation material that fills the empty space inside the vacuum vessel completely and thus provides the required mechanical support against the atmospheric pressure. The outer wall is allowed to “corrugate” under vacuum and to rest on the enclosed insulation. Through cold mass supports, the weight of the solenoid, its thermal contraction and the vacuum pressure are transferred to the end flanges and then further to the main detector support structure.
Cryogel® Z and 3M™ glass microspheres type K1 are chosen as insulation materials. Their radiation transparency, compression strength and thermal conductivity are investigated. The experimental results are used to design a mock-up cryostat manufactured in-house. Filled with an insulation material of choice, it allows to estimate the heat fluxes transferred to the thermal shield and to the cold mass of a real-case cryostat for different vacuum levels, boundary temperatures and compression loads applied to the insulation layers.
Size, radiation thickness and thermal budget are then estimated for a conceptual cryostat insulated with Cryogel® Z and are compared to those of alternative designs in order to make a critical evaluation of the feasibility of such a cryostat concept for large-scale detector magnets.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • ten Kate, H.H.J., Supervisor
  • Dhallé, M.M.J., Co-Supervisor
Award date16 Nov 2022
Place of PublicationEnschede
Publisher
Print ISBNs978-90-365-5470-1
DOIs
Publication statusPublished - 16 Nov 2022

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