The ALBA and BESSY II Linacs consist of a thermionic Pierce-type electron gun that delivers e- at 90 keV in pulses of 1 ns with a maximum charge of 0.25 nC/bunch. The gun is followed by a set of standing wave bunching cavities and traveling wave accelerating structures to further increase the beam energy, up to 50 MeV at BESSY II and up to 100 MeV at ALBA, while keeping the energy spread below 0.5% (rms). In this paper a study of the beam parameters at the exit of the electron gun is presented for different bunch charges, to evaluate the space charge effect. For that, electrostatic field maps have been obtained by means of Superfish, following the technical drawings provided by the manufacturer, Thales. Results from the simulations are compared to the values reported by the supplier at the exit of the gun, and also to real measurements performed at the BESSY II gun test-stand. The implementation of the field-maps of the gun at the Linac model (GPT tracking code) conducts more realistic simulations, improving the understanding of the two Linac beam performances.

A research project was initiated at HZB to develop a new E-Gun control system for the Linac Gun to realize the advanced demands from the BESSY II injection scheme. The Flexi-Gun system will allow significantly higher flexibility in both pulse load and pulse timing structure. The purpose built gun test stand is equipped with a diagnostic beamline. Developed and manufactured in-house, the potential for knowledge transfer has led to a collaboration with ALBA for start-to-end particle tracking simulations. This article presents the motivation and potential of the Flexi-Gun, the development of the driver board and control, and the first measurements of the beam parameters. With the "Flexi-Gun" project, the upgraded Linac E-Gun becomes the optimal injector for BESSY II.

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.