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The international effort for the PIP-II project at Fermilab has been joined by INFN with its planned contribution to the PIP-II proton linac in the low-beta section. INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, 36 plus spares resonators with 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry to reach the unprecedented performances required by PIP-II, qualified through vertical cold test at state-of-the art infrastructures and delivered as ready for the linac at the string assembly site. The status of INFN contribution to PIP-II, the development of infrastructures and prototypes as well as the ongoing activities toward the start of series production are summarized in this paper., Proceedings of the 20th International Conference on RF Superconductivity, SRF2021, East Lansing, MI, USA

INFN-LASA is currently involved in the production of PIP-II low-beta cavity prototypes. The main challenge of this activity is to develop a state-of-the art surface treatment recipe on such cavity geometry, to achieve the high-Q target required for cavity operation in the linac. This paper reports the status of cavity treatments development and the first cold test results of a single-cell cavity. This cavity has undergone a baseline treatment based on Electropolishing as bulk removal step. Being this test successful, a strategy for pushing the cavities towards higher performances is here proposed., Proceedings of the 20th International Conference on RF Superconductivity, SRF2021, East Lansing, MI, USA

INFN Milano - LASA contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. All the cavities have been mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold at DESY. We present the result of the cavities already qualified and delivered to CEA, discussing the lessons learnt so far. For remaining cavities, we discuss the actions taken and the plans foreseen to recover them to full specifications., Proceedings of the 20th International Conference on RF Superconductivity, SRF2021, East Lansing, MI, USA

The status of INFN-LASA contribution to the PIP-II project at Fermilab is reported in this paper. Experimental results and ongoing activities on prototypes are summarized together with the development of related testing infrastructures. The series production of the 38 5-cell, beta 0.61 cavities designed by INFN-LASA for the LB650 section of the PIP-II linac recently commenced, the status of major procurements and associated activities is here below presented. All cavities will be produced and surface treated in industry to reach the unprecedented performances required, qualified through vertical cold test at qualified infrastructures and delivered as linac-ready at the string assembly site., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The INFN LASA contribution to the European Spallation Source ERIC (European Research Infrastructure Consortium) Superconducting Linac is focused on supplying 36 cavities for the Medium Beta section of the proton accelerator. Twenty eight cavities have been fully qualified and delivered to CEA for integration into the cryomodules. We present the status of the activities dedicated to completing our contribution both by applying alternative surface treatments with respect to the series vertical BCP and by procuring new cavities., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

LASA-INFN is developing some PIP-II β=0.61 cavity prototypes so to set up a high-Q recipe allowing to reach the PIP-II performance target in view of the series production. A single-cell cavity was treated with a XFEL-like baseline recipe, whereas a multicell cavity underwent a mid-T bake step as final surface treatment. Both cavities have been then tested at the LASA vertical experimental facility. The test results are here reported and discussed. Basing on the satisfactory results so far obtained, a strategy for the qualification and upgrade of the LASA vertical test facility is outlined., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The BESSY VSR project aims to demonstrate the possibility to simultaneously run both long (15ps) and short bunches (1.7ps) within BESSY II storage ring. To achieve this, a new SRF cavity system with higher harmonic cavities (3 and 3.5 harm.) needs to be installed. The combined cavity SRF beating allows for stable bunch shortening for half of the buckets while standard lengths remaining for the other half. These SRF cavities will be equipped with waveguide-connected HOM absorbers and will be controlled with a blade tuner plus piezos. To demonstrate the feasibility of this complex system the VSR DEMO cold string consists of two 1.5 GHz cavities, each featuring five waveguides and a higher power coupler, plus all interconnecting elements coupled to the beam vacuum. For most of these components the fundamental development work is completed and has been reported in the past. This paper summarizes recent enhancements, component detailing and manufacturing status. The key cold string components such as cavities, higher power couplers and blade tuners have already entered the manufacturing phase. All other cold string components will be ready for purchase at the latest beginning of 2022., Proceedings of the 20th International Conference on RF Superconductivity, SRF2021, East Lansing, MI, USA

Standard vertical Buffered Chemical Polishing (BCP) is one of the main surface treatment for Superconducting Radiofrequency (SRF) cavities. A finite element Computational Fluid Dynamic (CFD) model has been developed. Uncertainties in the solution of fluid simulations are not negligible due to the complex geometry of a SRF cavity; thus without an experimental validation, results from this type of simulations cannot be confidently used to improve the process. To this aim, an experimental study was started to investigate the fluid dynamics of the BCP process by means of Particle Image Velocimetry (PIV) technique. Similitude on Reynolds number and Refractive Index Matching (RIM) technique were also implemented to replace the dangerous BCP mixture with a glycerine-water mixture. The paper describes the preliminary results from simulations and experiment., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

INFN Milano contributes in-kind to the ESS ERIC Superconducting Linac supplying 36 cavities for the Medium Beta section of the proton accelerator. The production has reached completion, being all the cavities mechanical fabricated, BCP treated and, for most of them, also qualified with vertical test at cold. In this paper, we report on the results and lessons learnt and the actions taken both for quality control managing and recovery of the few cavities that did not reach the project goal after the first qualification test., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

INFN joined the international effort for the PIP-II project at Fermilab and it’s going to contribute to the low-beta section of the PIP-II proton linac. In particular, INFN-LASA is finalizing its commitment to deliver in kind the full set of the LB650 cavities, namely 36 plus spares 5-cell cavities at 650 MHz and geometrical beta 0.61. All cavities, designed by INFN-LASA, will be produced and surface treated in industry, qualified through vertical cold test, and delivered as ready for string installation. This paper reports the status of INFN’s contribution to PIP-II and of ongoing activities toward the experimental qualifications of infrastructures and prototypes., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

This paper reports on the first results obtained by INFN-LASA on PIP-II low-beta cavity prototypes. The goal of this activity was to validate the reference surface treatment based on Electropolishing as a bulk removal step. The cavity treatment procedures are here presented together with the strategy used for their optimization. The experimental results of cavity cold tests for a single cell prototype are presented and discussed. Having this cavity achieved the requested performance, the baseline procedure is considered as validated and a plan for a future high-Q cavity surface treatment is proposed., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

INFN-LASA joined the international effort for the PIP-II project in Fermilab to build the 650 MHz superconducting cavities realizing the low-beta section of the 800 MeV proton linac. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results., Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany

The industrial production of the 36 resonators (plus 2 spares) for the ESS linac started and it is steadily progressing. Cavities are delivered by industry as fully surface-treated and dressed to AMTF facility at DESY for their qualification via vertical cold-test. This paper reports the current status of the manufacturing process from sub-components to processing of the complete cavity inner surface. It also reviews the documental control strategy deployed to preserve the fulfillment of ESS requirements as well as the cavity performances demonstrated so far., Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany

The LASA vertical test facility is equipped for the cold test of ESS medium-beta 704.42 MHz cavities, with and without He tank, and is integrated with several diagnostic tools allowing a careful analysis of cavity performance limitations. This paper reports the latest tests on ESS cavities - both prototypes and series - and a discussion on the experimental results. The recent instrumental upgrades implemented in the facility - and the ones foreseen for the future in view of a further improvement of cavity performances - are also pointed out., Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany

INFN-LASA joined the international effort for the PIP-II project in Fermilab and it is expected to build the 650 MHz superconducting cavities required by the low-beta section of the 800 MeV front-end proton linac, as recently signed by US DOE and Italian MIUR. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. In a joint effort with Fermilab the road for the optimal surface treatment for such low-beta resonators has started in order to approach the existing state-of-the-art performances of beta 1 cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

We present the upgrade of the EP facility for the surface treatment of PIP-II low beta cavities. The main process parameters, such as voltage, treatment time, acid throughput and cathode geometry, already optimized on the previous experience of 1.3 GHz Tesla-shape cavities, are discussed taking into account the different cavity size and geometry. The first surface treatments have been performed at Ettore Zanon SpA on single cell cavity prototypes in order to reach good final surface finishing and the required thickness removal. In the meantime, the upgrade of the system for the treatment of multicell PIP-II prototype cavities is presented., Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany

This paper describes the efforts made by LASA on the development of surface treatments for low-beta elliptical cavities, for the current series production of ESS and the foreseen series production of PIP-II. The traditional techniques of buffered chemical polishing and electropolishing are here discussed taking into account the industrial environment, the practical issues due to the size and geometry of such cavities and according to the required qualification values for quality factor and accelerating gradient., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The surface treatment of ESS 704 MHz medium beta cavities consists of a bulk BCP 200 micron removal, a 10 h 600°C heat treatment and a final 20 micron BCP performed after tank integration. The facility currently employed for the BCP treatment, settled in Ettore Zanon SpA, is here presented, together with the results so far obtained on the first series cavities in terms of frequency sensitivity, removal rate and surface external temperature. The optimization of BCP treatment by a preliminary fluid-dynamical finite element model is also discussed. Some details about the visual inspection procedure and the furnace qualification are also presented., Proceedings of the 19th International Conference on RF Superconductivity, SRF2019, Dresden, Germany

INFN-LASA contributes in-kind to the European Spallation Source ERIC with 36 6-cell cavities for the Medium Beta section of the Superconducting Linac. After having developed the electromagnetic and mechanical models, few prototypes have been produced and tested. Based on this experience, we are now supervisioning the cavity production at the industry, the resonators test at DESY and the delivery to CEA at Saclay. In this paper, we report on the status of the overall INFN-LASA contribution including also document handling, interface data exchange and QA/QC., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia