The beam screen for the Future Circular hadron-hadron Collider (FCC-hh) has a baseline design based on a copper (Cu) coating. Calculations have indicated that the resistive wall impedance will be the major contributor to the beam impedance for the FCC-hh at both injection and collision and that Cu might be on the limit to ensure beam stability. To increase the safety margin, it is desirable to reduce the resistive wall impedance. In this contribution, we present an approach to reduce the beam impedance based on the reduction of the surface resistance of the beam screen coating by using High-Temperature Superconductors based on REBaCu3O7-x coated conductors (REBCO-CCs). These HTS-CCs have transition temperatures around 90K, and critical current densities which are high enough even in the presence of strong magnetic field, being therefore good candidates to substitute Cu in the FCC-hh beam screen which will be operating at around 50K and under a magnetic field of 16T. Using experimental data generated on the surface impedance of REBCO-CCs, CST simulations have been performed and the beam impedance has been estimated for an elliptical beam screen with the same vertical dimensions as that of a pure Cu beam screen. A position and REBCO-CCs contribution dependence study to determine the optimum beam screen configuration will be shown. Resistive wall impedance studies using an ellipse is a step forward towards determining the performance of the REBCO-CCs on the FCC-hh beam screen.

ALBA is working on the upgrade project that shall transform the actual storage ring, in operation since 2012, into a 4th generation light source, in which the soft X-rays part of the spectrum shall be diffraction limited. The project was launched in 2021 with an R&D budget to build prototypes of the more critical components. The storage ring upgrade is based on a 6BA lattice which has to comply with several constraints imposed by the decision of maintaining the same circumference (269m), the same number of cells (16), the same beam energy (3GeV), and as many of the source points as possible unperturbed. At present, the lattice optimization, iterating with the technical constrains of space and performance, is ongoing. This paper presents the status of the project, with the present proposed lattice, first magnet’s designs, the vacuum chamber initial considerations, the girder concept, the proposed RF system with fundamental and harmonics cavities, and the general context of the upgrade.

The beam screen for the Future Circular hadron-hadron Collider (FCC-hh) has a baseline design based on a copper (Cu) coating. Calculations have indicated that the resistive wall impedance will be the major contributor to the beam impedance for the FCC-hh at both injection and collision and that Cu might be on the limit to ensure beam stability. To increase the safety margin, it is desirable to reduce the resistive wall impedance. In this contribution, we present an approach to reduce the beam impedance based on the reduction of the surface resistance of the beam screen coating by using High-Temperature Superconductors based on REBaCu3O7-x coated conductors (REBCO-CCs). These HTS-CCs have transition temperatures around 90K, and critical current densities which are high enough even in the presence of strong magnetic field, being therefore good candidates to substitute Cu in the FCC-hh beam screen which will be operating at around 50K and under a magnetic field of 16T. Using experimental data generated on the surface impedance of REBCO-CCs, CST simulations have been performed and the beam impedance has been estimated for an elliptical beam screen with the same vertical dimensions as that of a pure Cu beam screen. A position and REBCO-CCs contribution dependence study to determine the optimum beam screen configuration will be shown. Resistive wall impedance studies using an ellipse is a step forward towards determining the performance of the REBCO-CCs on the FCC-hh beam screen.

Vacuum chambers of flat aspect ratio are source of a quadrupolar component of long-range resistive wall wake fields whose amplitude only depends on the trailing test particle. In multi-bunch filling this leads to an accumulation of the long-range quadrupolar resistive wall wake field which expresses in multi-bunch tune shifts on both planes. The tune shifts were measured at the ALBA storage ring and the results were compared to the model of Chao, Heifets and Zotter * and the model of Blednykh et al.**. As ALBA runs with only 8 insertion devices of which 3 are in-vacuum undulators in relatively short sections with low beta-functions, the quadrupolar detuning is dominated by dipolar vacuum chambers and the standard vacuum chamber around the ring. The effect of the in-vacuum undulators will be also discussed.