Engineering news
A laser technology developed by the University of Dundee and the Science and Technology Facilities Council (STFC) could provide an affordable way to boost the performance of the Large Hadron Collider (LHC) at CERN to achieve new levels of efficiency.
The Dundee and STFC partnership with CERN will see the Laser Engineered Surface Structures (LESS) method deployed for surface modification of metals in order to clear the `electron cloud’ that develops in the LHC and limits the range of experiments that it can handle.
Professor Amin Abdolvand, chair of functional materials and photonics at the University of Dundee, said: “Large particle accelerators such as the Large Hadron Collider suffer from a fundamental limitation known as the ‘electron cloud’. This cloud of negative particles under certain condition may degrade the performance of the primary proton beams that circulate in the accelerator, which is central to its core experiments.
“Current efforts to limit these effects involve applying composite metal or amorphous carbon coatings to the inner surfaces of the LHC vacuum chambers. These are expensive and time consuming processes that are implemented under vacuum.”
As part of the High Luminosity LHC project, CERN is preparing to upgrade the collider from 2019 and a new solution is needed to reduce the electron cloud to much lower levels than are expected as the upgraded collider will use proton beams that will be double the intensity of the current ones.
The LESS method has been proven to reduce the electron cloud to “unprecedentedly low levels”. It involves using lasers to manipulate the surface of metals, and relies on understanding how different metal surfaces react when they are subjected to varying levels of laser ‘fluence’ or intensity.
Tests have shown that it is possible to reformulate the surface of the metals in the LHC vacuum chambers to a design that under a microscope resembles the type of sound padding seen in music studios. The surface can trap electrons, keeping the chambers clear of the cloud. The University of Dundee said that initial tests at the Super Proton Synchrotron, the LHC injector, have shown the LESS method is very effective at controlling the electron yield, as electron clouds have been fully eradicated.
Professor Lucio Rossi, project leader of the High Luminosity LHC, said: “If successful, this method will allow us to remove fundamental limitations of the LHC and reach the parameters which are needed for the high luminosity upgrade in an easier and less expensive way. This will boost the experimental program by increasing the number of collisions in the LHC by a factor over the present machine configuration.”
Peter McIntosh, deputy head of STFC’s Accelerator Science and Technology Centre (ASTeC), added: “Through close working interaction between ASTeC vacuum scientists and Dundee University laser specialists, a real breakthrough in suppression of secondary emission yield performance has been accomplished, which could have widespread implications for high electro-magnetic field environments, where breakdown limitations are of particular concern, such as for sensor systems and applications in satellite and aerospace technologies. We expect it will prove to be an innovative solution for CERN.”