This WP has been taken over by EuCARD-2, WP10: Future Magnets and the Future Circular Collider study.
High Energy LHC (HE-LHC) is a study aimed at exploring the possibility to upgrade the present LHC ring to reach an energy of 13 to 16. 5 TeV per proton beam, or 26 to 33 TeV centre-of-mass collision energy. The basic idea is to substitute the present main LHC superconducting magnets, with ones with much higher fields. For example the present 1232 15 m–long LHC dipoles, designed for a nominal magnetic field of 8.33 tesla, should be replaced by dipoles of operative field up to 20 tesla(for 33 TeV collision energy). Given the necessary margin, this means designing the dipole for a maximum theoretical field of 25 tesla! Beside the enormous challenge of such very high field magnets, HE-LHC poses challenges of handling the injection and ejection of the beam. Indeed the beam injection energy must be more than doubled, which means revamping the injector chain of CERN. Therefore, the kicker systems will have to handle beams of more than double the rigidity in a length that is practically constant, both for the beam in and out. A further challenge is handling a synchrotron radiation level that is 15-30 times the one that LHC will have at 14 TeV. This feature, however, does have the benefit of a strong synchrotron damping, helping beam stability, like for electron rings, a “prima” for hadron collider. These and other relevant points have been examined by a CERN Working Group led by CERN Director for Accelerator, Steve Myers, in 2010, see report. In October 2010 an international workshop with prominent scientists of hadron colliders from all over the world was organised under the FP7-Eucard networking Acc-Net, to examine the key points of the project, including the injector chain. The very encouraging conclusion can be found in the Proceedings. Based on this, at CERN the study HE-LHC has been set and integrated as management in the HiLumi project (also for the important synergy and overlaps). One important WP of the future FP7-Eucard2 (cite website…) will deal with the very high field HTS magnet needed for HE-LHC.
A second option, based on a new tunnel of about 60 km near CERN is also under consideration, both for increasing the energy reach and also for important synergy that this might have with a circular lepton collider of 300 GeV as Higgs factory.