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The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) has been delivered by the end of 2019. It has been provided by CEA, IRFU, Saclay/France. It consists of five sections with a total length of 4.6 m and accelerates the 70 mA proton beam from 75 keV up to 3.6 MeV. It will be fed with 900 kW peak power through two coaxial loop couplers. The installation process (alignment, vacuum test), as well as the tuning process based on bead-pull measurements, is presented in this paper., Proceedings of the 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be de-livered during 2019. It is provided by CEA, IRFU, Sac-lay/France. It consists of five sections with a total length of 4.6 m and accelerates the proton beam from 75 keV up to 3.6 MeV. It will be feed with 1.6 MW peak power through two coaxial loop couplers. This paper will present the manufacturing status of the five sections and the qualification test of the RF power couplers., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

One yet unanswered questions in physics today concerns the action of gravity upon antimatter. The GBAR experiment proposes to measure the free fall acceleration of neutral antihydrogen atoms. Installation of the project at CERN (ELENA) began in late 2016. This research project is facing new challenges and needs flexibility with hardware and software. EPICS modularity and distributed architecture has been tested for control system and to provide flexibility for future installation improvement. This paper describes the development of the software and the set of software tools that are being used on the project., Proceedings of the 16th Int. Conf. on Accelerator and Large Experimental Control Systems, ICALEPCS2017, Barcelona, Spain

The construction of Linac4, the new 160 MeV CERN H^{−} injector, has started with the goal of improving the LHC injection chain with a new higher energy linac. The low energy front end of Linac4 is based on a 352 MHz, 3-m long Radiofrequency Quadrupole (RFQ) which accelerates the 70 mA, 45 keV H^{−} beam from the ion source to the energy of 3 MeV. The RFQ, made of three modules, one meter each, is of the four-vane type and it has been designed in collaboration between CERN and CEA. Construction has started in 2009 and all the steps of machining and assembly have been done at CERN. The RFQ is equipped with 35 fixed tuners and one waveguide RF port located in the second module. This paper describes the procedure used to tune the accelerating field and the power coupler of the LINAC4 RFQ in order to achieve the nominal voltage profile within ±1% accuracy.

The RF design of a RFQ should satisfied several conditions, namely: voltage profile required by beam dynamics, a tunable structure, RF stability and reasonable sensitivity to possible perturbations induced by power operation. Voltage profile may be obtained either by a dedicated profiling of 2D cross-section and/or slug tuner adjustment. Tunability is directly related to spatial distribution of tuners. RF stability requires sufficient separation between accelerating quadrupole mode and (i) adjacent quadrupole modes, or (ii) adjacent dipole modes. Quadrupole modes separation is directly related to RFQ length, and can be increased if necessary via segmentation; position of dipole modes spectrum w.r.t. quadrupole spectrum may be adjusted using rod stabilizers inserted at RFQ ends and on either side of coupling circuits. We present a thorough comparison of these two options for a 6-meter long structure at 352 MHz, and show they both lead to a tunable structure. The design includes 3D electromagnetic simulation and application of transmission line to tuning. The sensitivity of both designs to perturbations is also evaluated., Proceedings of the 1st International Particle Accelerator Conference, IPAC2010, Kyoto, Japan