An overview of the project status of the future Italian 2.4 GeV 4th generation light source Elettra 2.0 that will replace the existing 3rd generation light source Elettra is presented, including challenges and perspectives in the design and construction of such light sources. Elettra 2.0 will be the ultra-low emittance light source that will provide ultra-high brilliance and coherence and at the same time also aims to provide very short pulses for time resolved experiments. The discussion includes the technical challenges requiring specific R&D studies, for example on injection schemes, high performance magnets, vacuum, diagnostics for stability, feed-backs, harmonic cavities, etc. The upgrade also addresses on the request from the established user community to minimize the duration of beam-time interruption, imposing the need of a careful organization and planning of all the phases of the project, from the removal of the old machine to the installation and successful commissioning of the new one.

The Elettra 2.0 upgrade project requires the realization of a new storage ring that will replace the existing one of Elettra. The Elettra 2.0 optic, developed on the basis of the magnet feasibility studies, include a total of 552 iron-dominated electro magnets, with all sextupoles and octupoles equipped with additional coils to achieve the combined fields of corrector and skew quadrupoles. This paper reports all the latest magnetic and pre-engineered designs and the comparison with the main magnet prototype performances.

We investigate the upgrade of Elettra 2.0 to radio-frequency transverse deflecting cavities generating a steady-state vertical deflection of selected electron bunches. The study demonstrates the feasibility of 1 to few ps-long x-ray pulses at MHz repetition rate provided simultaneously to several beamlines, and transparent to the standard multi-bunch operation. The short pulse exhibits total flux at 1-10% level of the standard single bunch emission, and transverse coherence preserved in both transverse planes up to approximately 0.5 keV.

One of the main characteristics of the future light sources like Elettra 2.0 is the small vacuum chamber cross section. In fact, the resistive-wall (RW) impedance due to the small vacuum chambers cross section enhances transverse coupled-bunch instabilities. In this study, the effect of the RW in the multi-bunch case is investigated versus chromaticity. The threshold currents in the presence of broad-band and RW impedances are estimated for the Elettra 2.0 storage ring at different values of chromaticity using macroparticle tracking and frequency domain semi-analytical calculations. In particular, it is found that, above a certain chromaticity, the threshold current is determined by the radial head-tail modes. In view of mitigating these instabilities, the effectiveness of the transverse bunch-by-bunch feedback system as well as bunch-lengthening harmonic cavities is also useful.

Due to the reduced diameters of the vacuum chambers and of the other equipment, the performance of the next generation light sources can be greatly affected resulting in a reduction of the intensity in both single and multi-bunch operations. This is particularly important for Elettra 2.0 since there are plans to incorporate bunch compression schemes for providing very short photon pulses. In this study, the resistive wall and single bunch instabilities are investigated by tracking in order to define their thresholds.

The effect of both existing and the planned insertion devices on linear optics, dynamic and momentum aperture was modeled using the kick map approach. Cross check for some IDs have been done with different tracking codes. Mitigation strategy for avoiding the crossing of a 4th order resonance line, excited by some of the IDs, is proposed.

The accurate analysis of any possible source of beam instability is mandatory for the design of a new particle accelerator, especially for high current and ultra low emittance synchrotrons. In the specific case of instabilities driven by the coupling between the charged particle beam and the electromagnetic field excited by the beam itself, the corresponding effect is estimated through the beam coupling impedance. The modeling of this effect is fundamental to perform a rigorous evaluation of the coupling impedance budget able to account for all devices present in the entire machine. To deal with this problem, this paper focuses on the estimation of the contribution of the joints lying between the different vacuum chamber sections, by performing a comparative numerical analysis that takes into account for different aperture gaps between the flanges. The results point out the criticality of many small-impedance contributions that, added together, must be lower than a predefined impedance threshold.

The Elettra 2.0 upgrade project is a new storage ring that will replace the existing Elettra. Among the project's flagships are those of three beamlines with a photon flux generated by dedicated bending magnets of up to 10^13 ph/ses at 50 keV. Since a magnetic field of around 6 tesla is needed to do this, the magnet designed for those beam lines will employ superconducting technologies, for what it's called superbends. The installation of those three superbends is scheduled in the 2026 while the test of the first prototype at the beginning of 2025. This paper reports the main magnetic characteristics of the superbend model as well as the mechanical and cryogenic preliminary design.

The current injector system, composed by a linac and a synchrotron booster, will be used to inject into the new storage ring. After 15 years of operation, some upgrade of the instrumentation devices are required to well characterize the beam parameters extracted from the booster, before and after the implementations in action to reduce the beam emittance.