Conceptual study of the cryostats for the cold powering system for the triplets of the High Luminosity LHC

A Ballarino,A Jacquemod,S Giannelli,Y Leclercq,V Parma,C Ortiz Ferrer

doi:10.1088/1757-899x/278/1/012155

Abstract

The High Luminosity LHC (HL-LHC) is a project aiming to upgrade the Large Hadron Collider (LHC) after 2020-2025 in order to increase the integrated luminosity by about one order of magnitude and extend the operational capabilities until 2035. The upgrade of the focusing triplet insertions for the Atlas and CMS experiments foresees using superconducting magnets operating in a pressurised superfluid helium bath at 1.9 K. The increased radiation levels from the particle debris produced by particle collisions in the experiments require that the power converters are placed in radiation shielded zones located in a service gallery adjacent to the main tunnel. The powering of the magnets from the gallery is achieved by means of MgB2 superconducting cables in a 100-m long flexible cryostat transfer line, actively cooled by 4.5 K to 20 K gaseous helium generated close to the magnets. At the highest temperature end, the helium flow cools the High Temperature Superconducting (HTS) current leads before being recovered at room temperature. At the magnet connection side, a dedicated connection box allows connection to the magnets and a controlled boil-off production of helium for the cooling needs of the powering system. This paper presents the overall concept of the cryostat system from the magnet connection boxes, through the flexible cryostat transfer line, to the connection box of the current leads.

Highlights

The principal part of the High Luminosity Large Hadron Collider (HL-LHC) project [1] requires the installation of new triplet insertions focusing the beams at each side of the Atlas and CMS interaction points
For the DFX-SC Link-DFH chain of cryostats, up to about 220 electrical connections operating at cryogenic temperatures have to be installed, tested and properly cooled
Advantages are numerous, this ensures that the mechanical loads from vacuum, thermal contractions, SC link stresses and pressure fluctuations of the cryogenic circuits do not affect the beam tube alignment but it leads to lighter components, easier to transport, manufacture, control and maintain, that can be installed independently without the tight specifications inherent to the beam tube

Summary

Introduction

The principal part of the High Luminosity Large Hadron Collider (HL-LHC) project [1] requires the installation of new triplet insertions focusing the beams at each side of the Atlas and CMS interaction points. The powering of the triplet insertion magnets is performed via a flexible superconducting line (hereafter called “SC link”) about 100 meters long, connected to the magnets on one end and to the power converters on the other end through dedicated connection cryostats referred respectively in the LHC naming convention as DFX and DFH, see figure 1. The High Luminosity HL-LHC project [1] will include four of these SC links with DFHDFX connection cryostats and will be installed in the LHC tunnel in 2024-2025.

Conceptual design of the cryostats of the cold powering system

Conclusion