Design of the future circular hadron collider beam vacuum chamber

Abstract

EuroCirCol is a conceptual design study of a post-LHC, Future Circular Hadron Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers. The vacuum chamber of this 100 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation linear power for proton colliders, 160 times higher than in the LHC for baseline parameters, releasing consequently much larger amounts of gas into the system. At the same time, it will be dealing with a tighter magnet aperture. In order to reach a good vacuum level, it has been necessary to find solutions beyond the particle colliders' state of art. This paper proposes a design of a novel beam screen, the element responsible for absorbing the emitted power. It is intended to overcome the drawbacks derived from the stronger synchrotron radiation while allowing at the same time a good beam quality.

Commissioning of a beam screen test bench experiment with a future circular hadron collider type synchrotron radiation beam

“…The BESTEX was conceived to perform studies on FCC-hh BS prototypes. As described elsewhere [6,10], the design of the FCC-hh BS implements a main chamber (MC) and an antechamber (AC) separated by a shield plate. A vertical slot aperture, located at the BS's equatorial plane, allows the SR to travel from the MC to the AC and impinge at its inner walls.…”

“…The AC's inner walls implement a stainless steel photon reflector tip, whose functionality and description are out of the scope of this paper. In agreement with the FCC-hh normal operation scenario [6], the collimator's opening at the BESTEX is set to allow a 2-mm-high SR beam to travel through the 5 mm BS prototype's slot. The propagation of the errors assumed at the collimator and the sample position (see Sec.…”

“…Distributed along the samples, several pumping holes allow the escape of the desorbed molecules, which in the case of the FCC-hh would eventually be pumped by the 1.9 K superconducting magnet cold bore [4,6] located at its outer part.…”

“…The FCC-hh, studied as a successor of the Large Hadron Collider (LHC), aims to expand the current energy frontiers, providing hadron collisions at a center of mass of 100 TeV [2][3][4]. During its operation, proton beams stored in the FCC-hh's arcs would originate unprecedented levels of SR for hadron machines [4][5][6][7]. Under these conditions, the limits at which the FCC-hh can operate are determined by the capabilities of minimizing SR-related effects, such as heat load, photon stimulated desorption (PSD), and photoelectron generation.…”

“…As in the case of the LHC [8,9], big efforts have been put into the design of the FCC-hh beam screen (BS) [6,10], which is essential to protect the cold superconducting magnets from the direct irradiation high-power SR photon beams. The validation of the current FCC-hh BS design requires one to analyze the response of the corresponding BS prototypes under significant levels of SR. To that end, in order to explore the vacuum performance of the FCC-hh BS, a beam screen test bench experiment (BESTEX) was designed and built at CERN and installed in the 2.5 GeV electron storage ring Karlsruhe Research Accelerator (KARA) light source at the Karlsruhe Institute of Technology (KIT).…”