Thermomechanical study of complex structures in the aperture of superconducting magnets: application to the design of the High-Luminosity LHC shielded beam screen
File(s)
Author(s)
Morrone, Marco
Type
Thesis
Abstract
In the framework of the High-Luminosity Large Hadron Collider (HL-LHC) project, a complex structure,
known as the beam screen, will be installed by 2024 in the aperture of the inner triplet superconducting magnets
nearby the ATLAS and CMS experiments. The beam screen is an octagonal shaped pipe that shields the 1.9 K
magnet cryogenic system from the heat loads and damage to the magnet coils that would be otherwise induced
by the highly penetrating collision debris. It also ensures that the vacuum conditions, required for the stability
of the beam, are met. This thesis describes the design of the beam screen and proposes extensions to important
components and features. The unknown physical properties of the beam screen materials have been characterised.
The thermal behaviour of the beam screen during normal working conditions has been optimised by simulations
and validated by measurements. The behaviour of the beam screen during a magnet quench, a resistive transition of
the superconducting magnet, has been studied. Two magnet quench protection systems have been considered: the
Quench Heaters (QH) by themselves and in conjunction with the Coupling Loss Induced Quench (CLIQ) device.
To this purpose two innovative coupled multiphysic models have been developed, which have been verified by
comparison with a closed form expression showing the advantages of considering self-inductance phenomena. In
the case of the QH the force distribution per quadrant gives rise to forces up 330 N/mm in the beam screen closest
to the interaction point, while in the case of the CLIQ a torque load-type is induced, whose maximum intensity
is around 2 N m/mm. With the new multiphysic models an unprecedented level of accuracy has been achieved,
which has permitted to demonstrate the mechanical integrity of the proposed beam screen design during a quench.
known as the beam screen, will be installed by 2024 in the aperture of the inner triplet superconducting magnets
nearby the ATLAS and CMS experiments. The beam screen is an octagonal shaped pipe that shields the 1.9 K
magnet cryogenic system from the heat loads and damage to the magnet coils that would be otherwise induced
by the highly penetrating collision debris. It also ensures that the vacuum conditions, required for the stability
of the beam, are met. This thesis describes the design of the beam screen and proposes extensions to important
components and features. The unknown physical properties of the beam screen materials have been characterised.
The thermal behaviour of the beam screen during normal working conditions has been optimised by simulations
and validated by measurements. The behaviour of the beam screen during a magnet quench, a resistive transition of
the superconducting magnet, has been studied. Two magnet quench protection systems have been considered: the
Quench Heaters (QH) by themselves and in conjunction with the Coupling Loss Induced Quench (CLIQ) device.
To this purpose two innovative coupled multiphysic models have been developed, which have been verified by
comparison with a closed form expression showing the advantages of considering self-inductance phenomena. In
the case of the QH the force distribution per quadrant gives rise to forces up 330 N/mm in the beam screen closest
to the interaction point, while in the case of the CLIQ a torque load-type is induced, whose maximum intensity
is around 2 N m/mm. With the new multiphysic models an unprecedented level of accuracy has been achieved,
which has permitted to demonstrate the mechanical integrity of the proposed beam screen design during a quench.
Version
Open Access
Date Issued
2018-01
Date Awarded
2018-06
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Aurisicchio, Marco
Garion, Cedric
Childs, Peter
Publisher Department
Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)