Beam Loading with the First Rebuncher of Spiral2, First Measurements

International audienceIn the SPI2 project the middle energy line (LME) is equiped with a radio frequency qupole and three Rebunchers. The subject of this article is to measure and characterise the effect of the beam loading on the first Rebuncher cavity

Superconducting Cavity and RF Control Loop Model for the SPIRAL2 Linac

International audienceThe SPIRAL2 superconducting linac has been successfully commissioned with protons in 2020. During the commissioning, a model of the cavity and its LLRF control loop has been developed. The model enables to have better understanding of the system and was used to guide the tuning of the PI(D) correctors for beam loading compensation. Here we review the development of such a tool, computed with MATLAB Simulink and using the frequency domain (Laplace transfer function) to model the cavity RF and mechanical behaviours (Lorentz detuning), as well as all elements that compose the RF control loop (digital LLRF, amplifier, transmission lines, etc.). The benchmarking of the model with measurement carried out with the proton beam is also discussed in this contribution

Cryogenic thermo-acoustic oscillations highlight and study in the SPIRAL2 superconducting LINAC

Cryogenic thermoacoustic oscillations is an area of interest of several studies. For superconducting accelerators, it is an unwanted phenomena that we usually want to get rid off. The SPIRAL2 superconducting accelerator had distributed Taconis all over its cryostats. This paper spans the different steps from their first detection to their damping with a highlight on the methods and the instrumentation that has been used. The presented study also sets the ground for a real life experimental investigation of thermo-ascoustics in complex geometries such as superconducting LINACs. With modern Big data analysis and simulation tools, it also sets the ground for the developments of new data linked codes that fit these complex situations

Cryogenic thermo-acoustic oscillations highlight and study in the SPIRAL2 superconducting LINAC

Cryogenic thermoacoustic oscillations is an area of interest of several studies. For superconducting accelerators, it is an unwanted phenomena that we usually want to get rid off. The SPIRAL2 superconducting accelerator had distributed Taconis all over its cryostats. This paper spans the different steps from their first detection to their damping with a highlight on the methods and the instrumentation that has been used. The presented study also sets the ground for a real life experimental investigation of thermo-ascoustics in complex geometries such as superconducting LINACs. With modern Big data analysis and simulation tools, it also sets the ground for the developments of new data linked codes that fit these complex situations

Three Years of Operation of the SPIRAL2 SC LINAC- RF Feedback

International audienceThe superconducting LINAC of SPIRAL2 at the GANIL facility has been in operation since October 2019. The accelerator uses 12 low beta and 14 high beta supercon-ducting quarter wave cavities, cooled at 4°K, working at 88 MHz. The cavities are operated at a nominal gradient of 6.5 MV/m and are independently powered by a LLRF and a solid-state amplifier, protected by a circulator. Pro-ton and deuteron beam currents can reach 5 mA and beam loading perturbation is particularly strong on the first cavities, as they are operated at field levels much lower than the nominal one. This paper presents a feedback after three years of oper-ation, focuses on the RF issues, describing problems and required improvement on the low level, control and pow-er system

First full cool down of the SPIRAL 2 superconducting LINAC

International audience• First full cool down of the SPIRAL 2 superconducting linear accelerator. • Cool down requirements methods and procedures as well as actual data. • Preparing the operation mode through experimental run. • New multidisciplinary challenges between cryogenic and RF for superconducting accelerator

RF Power Test of the Rebuncher for Saraf-Linac

International audienceThree normal conducting rebunchers will be installed at the Medium Energy Beam Transport (MEBT) of the SARAF-LINAC phase II [saraf]. The MEBT line is designed to follow a 1.3 MeV/u RFQ, is about 5 m long, and contains three 176 MHz rebunchers providing a field integral of 10⁵ kV. CEA is in charge of the design and fabrication of the Cu plated stainless steel, 3-gap rebuncher. The high power tests and RF conditioning have been successfully performed at the CEA Saclay on the first cavity. A solid state power amplifier, which has been developed by SNRC and has been used for the RF tests. The cavity has shown a good performance according to calculations, regarding the dissipated power, peak temperatures and coupling factor. RF conditioning was started with a duty cycle of 1\% and increased gradually until continuous wave (CW), which is the nominal working mode in SARAF-LINAC