CERN Cryogenic Turbulence Facility Switzerland

Facility and equipment

Overview

The importance of cryogenic He flows for the study of turbulence in high Reynolds regimes, as an invaluable complement to the experimental studies conducted on “conventional” fluids, was strongly reaffirmed – if need there was - during the 3-days EuTuCHe international workshop held at CERN in April 2007 (http://indico.cern.ch/internalPage.py?pageId=3&confId=11920). More than 60 researchers from 10 countries gathered to discuss the achieved and potential results deriving from the use of helium at cryogenic temperatures for turbulence analysis, and their connections and synergies with the studies conducted in room temperature fluids. It was clear that the whole turbulence research community would largely benefit from widened access to state-of-the-art large-scale cryogenics installations.

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Notwithstanding the workload already charged on CERN cryogenics park, CERN is offering a unique opportunity to direct and indirect access to the GReC installation to a number of European researchers, up to now prevented from benefiting from the advantages of cryogenics flows due to the high costs and complex technologies involved. Fully conscious of the role that it can play in this direction, CERN has accepted to reserve a non negligible fraction of the yearly access to this installation to groups of turbulence researchers in the context of a TNA programme

Beside the direct scientific advances that will be brought by this new programme, it is also expected an important cultural impact on the participants. Not only through the dissemination of technical knowledge relevant to cryogenics and its use for science, but also, in a more general sense, through the direct contact with the scientific environment of HEP at CERN, a real melting pot of scientific, technical and cultural skills. The “hands-on” contact with the world’s largest international research centre, where scientists from different institutes and countries cooperate in a structured and integrated way to reach the required critical mass for fundamental science advances, each one still preserving his own autonomy and visibility, will certainly produce positive effects in terms of culture of structured scientific cooperation.

GReC (CERN Cryogenic Turbulence Facility)

Operated in a stand-by duty service, the in­stallation works without interruption throughout the year, except for the two weeks of end-of-year closure of CERN and four weeks of yearly maintenance for each installation. It is hosted in the CERN SM18 cryogenic test facility. Its principal use is for the R&D, test and commissioning work on cryogenic components for High Energy Physics accelerators and experiments (like superconducting magnets or accelerating superconducting cavities operating down to 1.9 K). The installation is part of the unparalleled CERN cryogenics inventory, which includes 8 refrigerators with 18 kW power at 4.5 K, 2 refrigerators with 6 kW at 4.5 K and 14 others with power from 0.1 to 1.5 kW at 4.5 K.

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These characteristics make at present of CERN the absolute world-wide reference for large-scale cryogenics infrastructures, in terms of both installations and technical knowledge available on site. Many users from institutes collaborating to the LHC programme or to other HEP activities traditionally access the CERN cryogenic park every year. In the past few years, a group of researchers from different institutes in Grenoble proposed to CERN the use of one 6 kW at 4.5K refrigeration plant for dedicated turbulent experiments: a special removable coaxial transfer line was designed, built and connected to a large cryostat used for the tests of cavities, and the GReC installation (Grands Reynolds Cryogéniques) was born. Although the extremely reduced access time available at that time, GReC successfully met the requirements of producing a controlled free jet with an integral Reynolds number ReD ranging from 7.7×105 to 1.01×107 (Rel from 1750 to 7100) in extremely stable conditions: <±5% in mass flow and ≤±1% in temperature and pressure.

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Installation of probes specifically developped for Euhit access (WP21)