Abstract
Coping with synchrotron radiation (SR) that originated at superconducting bending magnets is one of the major challenges in the design of the vacuum beam pipes of hadron colliders. In the case of the Future Circular hadron Collider (FCC-hh), similarly as for the LHC, a beam screen, operating at higher temperatures than the cold mass, has been designed in order to preserve the superconducting magnet cold bores from direct synchrotron irradiation. The quality of the beam screen vacuum can be severely compromised by the absorption of SR into its walls, enhancing the risk for numerous beam detrimental effects to arise. In order to experimentally study such effects and develop strategies for their minimization, a beam screen test bench experiment (BESTEX) has been conceived and installed in the Karlsruhe Research Accelerator storage ring at the Karlsruhe Institute for Technology. The BESTEX has been designed to explore photon stimulated desorption, photon reflectivity, photon heat loads, and photoelectron generation originated on beam screen prototypes under irradiation of the FCC-hh-like SR spectrum. A detailed description of the BESTEX, its commissioning, and its functionality is hereby presented.
Highlights
Synchrotron radiation (SR) is known to be at the origin of numerous detrimental beam effects in particle accelerators [1]
This is specially true for photon stimulated desorption (PSD) results, since molecular yields are known to be affected by the surface chemical changes that take place when exposed to baking temperatures
The first results obtained during the commissioning period of the BESTEX have shown the capability to perform studies on synchrotronrelated effects on non-leak-tight samples such as the FCC-hh beam screen prototypes
Summary
Synchrotron radiation (SR) is known to be at the origin of numerous detrimental beam effects in particle accelerators [1] The severity of these SR countereffects is significantly enhanced when considering the construction of machines beyond the cutting edge of collision energies such as the Future Circular hadron Collider (FCC-hh). 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. Because of the similarities between KARA and FCC-hh’s SR spectra and critical energies (defined as the energy at which the SR power spectrum is divided in two equal parts), the simulation techniques used to estimate the response of the samples tested in the BESTEX can be applied to the actual FCC-hh BS during machine operation
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