Powerful ERL for experiments (PERLE) is a novel energy recovery linac (ERL) test facility [1], designed to validate choices for a 50 GeV ERL foreseen in the design of the Large Hadron Electron Collider and the Future Circular Collider and to host dedicated nuclear and particle physics experiments. Its main goal is to demonstrate the high current, continuous wave, multipass operation with superconducting cavities at 802 MHz. With very high beam power (10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERLs and becomes a "stepping stone" between the present state-of-the-art 1 MW ERLs and the future 100 MW scale applications.

Four models of the PHOENIX ECR charge breeder have been manufactured for ISOL application. Two are currently under operation at TRIUMF (ISAC) and GANIL (SPIRAL 1) while the SPES one is being installed on the facility. The last model is set on the LPSC 1+N+ test bench where a R&D program is ongoing to improve its performances. The last modifications consisted in improving the beam line vacuum and the alignment. Commissioning experiments showed an improvement of the charge breeder performances for all the tested species. The global CB efficiency is close to 100% for Cs when correcting the measurements with the beam transmission. Na and K efficiencies have increased significantly to reach 18.7% for Na8+ and 22.7% for K9+. In parallel, the charge breeder plasma was studied injecting short pulses of 1+ ions and using a zero-dimension model to estimate the plasma parameters. These experiments have provided a better understanding of the performance improvement. The last developments of the LPSC Charge Breeder together with the experimental results are presented.

Multipactor (MP) is an undesired phenomenon of resonant electron build up encountered on particle accelerators. It can induce anomalous thermal losses, higher than the Joule losses, inducing a decrease of the superconducting cavities quality factor, it can even lead to a cavity quench. On couplers, it can produce irreversible damages or generate a breakdown of their vacuum window. Multipactor may lead to Electron Cloud build up as well. The accelerator group at LPSC has developed a test bench dedicated to the multipactor studies. This paper presents the experimental set-up and its first measurements.

The goal of MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100 MW Accelerator Driven System (ADS) by building a new flexible irradiation complex at Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton current of 4 mA in continuous wave operation, with an additional requirement for exceptional reliability. Supported by SCKCEN and the Belgian federal government the project has entered in its phase I: this includes the development and the construction of the linac first part, up to 100 MeV. We here review the MINERVA linac vacuum system modelling studies that enabled to validate the choice of materials and vacuum equipment. The strengths and weakness of the vacuum design, highlighted by the models, will be discussed as well as the required improvements. INTRODUCTION The MYRRHA [1, 2] (Multi-Purpose Hybrid Reactor for High Tech Applications) project aims at building an ADS (Accelerator Driven System) demonstrator to study the technical feasibility of nuclear wastes incineration. It consists of a high power proton accelerator (4 mA – 600 MeV) which has to maintain a very high level of reliability to guaranty the robustness and the availability of the driven reactor [3, 4]. The MINERVA (MYRRHA Isotopes productioN coupling the linEar acceleRator to the Versatile proton target fAcility) project is the first phase of MYRRHA project. It consists of the construction of the linear accelerator up to 100 MeV. MINERVA accelerator (Fig. 1) is composed of): the LEBT (Low Energy Beam Transport), the RFQ (Radio Frequency Quadrupole), the CH cavity Booster, the MEBT-3 (Medium Energy Beam Transport), single spoke superconducting linac and HEBT beam transfer lines. Figure 1: Conceptual scheme of MYRRHA [5]. The vacuum layouts of the different sections have been defined [6]. The vacuum level requirements are similar to other high power proton linacs. It depends on the section and the used accelerating technology: normal conducting (NC) or superconducting (SC). It can go from 10-6 to 10-10 mbar. In general, dry vacuum pumps will be used and, if necessary, a bake out will be performed. Vacuum system modelling was realized according to the mechanical designs or constructed elements (such as the LEBT and RFQ [7]). For other parts the vacuum model is based on the architecture defined with the beam dynamics model. And we used a conservative assumptions to highlight points of attention. VACUUM DESIGN The LEBT, the RFQ and the first half of the CH-Booster mechanical designs are already defined. Thus, for those sections, the model is realistic. The second half of the CHBooster is similar to the first half, so it can be considered as defined. The MEBT-3 mechanical design is under definition. For this section, vacuum system modelling is considered “disadvantageous” (with a minimum of pumping ports) to be pessimistic and to orientate the final design. As for the single spoke linac section, the single spoke cavities are defined and the warm sections between each cryomodules are almost defined, so the model is realistic. To improve the space charge compensation (SCC) [8], and in particular the beam neutralization transient time, it has been envisaged to keep a pressure level of 10-5 to 5×10-5 mbar, with possible injection of Argon or Krypton gas into the LEBT. The collimator cone at the end of the LEBT reduces the conductance and the gas flux from the LEBT to the RFQ. The end of MEBT-3 and the main superconducting linac are using spoke cavities cryomodules, operating at 2 Kelvin. All the guiding and focusing magnetic elements operate at ambient temperature. To limit the pollution, a bake out has to be performed on the whole MEBT-3 and single spoke linac. Required vacuum levels in mbar of the different sections are shown in Table 1. Table 1: Required Vacuum Levels LEBT RFQ CHBooster MEBT-3 Spoke linac 10-6 to 2×10-5 10-7 to 5×10-7 8×10-8 to 3×10-7 10-10 to 10-9 10-10 to 10-9 ___________________________________________ * Work supported by a cooperation agreement between SCK CEN and CNRS/IN2P3 † rey@lpsc.in2p3.fr 12th Int. Particle Acc. Conf. IPAC2021, Campinas, SP, Brazil JACoW Publishing ISBN: 978-3-95450-214-1 ISSN: 2673-5490 doi:10.18429/JACoW-IPAC2021-TUPAB395 MC7: Accelerator Technology T14 Vacuum Technology TUPAB395 2443 C on te nt fr om th is w or k m ay be us ed un de rt he te rm s of th e C C B Y 3. 0 lic en ce (© 20 21 ). A ny di st ri bu tio n of th is w or k m us tm ai nt ai n at tr ib ut io n to th e au th or (s ), tit le of th e w or k, pu bl is he r, an d D O I

The goal of the MYRRHA project is to demonstrate the technical feasibility of transmutation in a 100 MWth Accelerator Driven System by building a new flexible irradiation complex at Mol (Belgium). The MYRRHA facility requires a 600 MeV accelerator delivering a maximum proton current of 4 mA in continuous wave operation, with an additional requirement for exceptional reliability. Supported by SCKCEN and the Belgium government the project has entered in its phase I (MINERVA): the construction of the linac first part, up to 100 MeV. We review the design updates of the superconducting linac. CONTEXT MYRRHA (Multi-purpose Hybrid Research reactor for High-tech Applications) is a fast spectrum research reactor that is planned to be operational around 2033 at SCK●CEN Mol (Belgium) [1]. The facility is especially designed to demonstrate the feasibility of high-level waste transmutation with an Accelerator Driven System (ADS). MYRRHA requires a powerful proton accelerator (600 MeV, 4 mA) operating in CW mode. The accelerator must, above all, fulfil very stringent reliability requirements to ensure the safe ADS operation with a high level of availability. The actual maximum limit is set to 10 beam interruptions (longer than 3 seconds) per 3-month operating cycle. The conceptual design of such an ADS-type accelerator has been initiated during previous EURATOM Framework Programmes (PDS-XADS and EUROTRANS projects) and consolidated in the MAX project** [2] [3]. It is a linac based solution (see Figure 1) that brings good electric efficiency thanks to the use of superconductivity and high potential for reliability by the use of several redundancy schemes. It is composed of two distinct sections. A low energy (normal conducting) injector where a 30 keV beam is transported through the Low Energy Beam Transport line (LEBT) [4] and matched to a 176 MHz 4rod RFQ [5]. The 1.5 MeV bunched beam at the RFQ output is then accelerated up to 16.6 MeV by CH-cavities [6]. In the injector modularity and fault tolerance are not easily applicable because of the low beam velocity. Here redundancy is applied in its parallel form, and so two similar compact injectors with fast switching capabilities are foreseen. A medium and high energy section (main SC linac), highly modular, based on individual, independently controlled accelerating superconducting cavities. In this section, serial redundancy is applied to guarantee a strong tolerance to faults, thanks to a fault compensation scheme [7]: a cavity fault is mitigated locally and taken over by retuned adjacent cavities. The MYRRHA construction is now following a phasing approach. The first phase consists in building and operating the linac limited to a 100 MeV final beam energy [8]. The principle aim of phase I is to experimentally investigate the feasibility and efficiency of the linac reliability and fault tolerance schemes. It is foreseen to transport the 100 MeV beam to different irradiation stations to produce innovative medical radioisotopes and radioactive beam with an ISOL production target for innovative medical radioisotopes. MINERVA corresponds to the phase I of the project that combines: the 100 MeV linac, the target station and the associated services and buildings. Figure 1: MYRRHA & MINERVA linac scheme. SC LINAC ARCHITECTURE The architecture of the SC linac is summarised in Table 1. It is composed of an array of independently-powered superconducting cavities with high energy acceptance and moderate energy gain per cavity (low number of cells and very conservative accelerating gradients), the goal being to increase as much as possible the tuning flexibility and to provide sufficient margins for the implementation of the fault-tolerance scheme. Three distinct cavity families are used to cover the full energy range: single and double spoke (ESS type) cavities at 352.2 MHz and 5-cells elliptical cavities at 704.4 MHz. Such a choice is based on the results of a longitudinal optimisation using the GenLinWin simulation code [9]. Compared to the previous design [3] it has been decided to: use ESS double-spoke cavities [10] in section #2, to decrease the synchronous phases of the first cavities and to increase the nominal accelerating gradient, especially in section #1. Such choices are the result of errors studies ___________________________________________ * Part of this work is supported by the European Atomic Energy Community’s (EURATOM) H2020 Programme under grant agreement n°662186 (MYRTE project). † frederic.bouly@lpsc.in2p3.fr ** FP7 projects: MAX R&D under grant agreement n° 269565 10th Int. Partile Accelerator Conf. IPAC2019, Melbourne, Australia JACoW Publishing ISBN: 978-3-95450-208-0 doi:10.18429/JACoW-IPAC2019-MOPTS003 MC4: Hadron Accelerators A08 Linear Accelerators MOPTS003 837 Co nt en tf ro m th is w or k m ay be us ed un de rt he te rm so ft he CC BY 3. 0 lic en ce (© 20 19 ). A ny di str ib ut io n of th is w or k m us tm ai nt ai n at tri bu tio n to th e au th or (s ), tit le of th e w or k, pu bl ish er ,a nd D O I

Electron cyclotron resonance charge breeder (ECR CB) is one of the instruments used to boost the radioactive ion beam (RIB) charge state (from 1+ to N+) in isotope separator on-line (ISOL) facilities. While existing ECR CB can manage intense incoming 1+ RIB without difficulty, significant amounts of background impurities are extracted with the N+ RIB signal. When the N+ RIB signal is very low, the dominant background can be detrimental to the study of the RIB in today facilities, if no downstream high mass resolution separation is available. This work investigates the improvements achievable with a new generation 18 GHz ECR CB applicable to future facility like EURISOL. The study shows that with a modified ion source geometry, an optimized magnetic confinement, a careful wall metal choice like beryllium, a UHV technology, the charge breeder performance will improve as follows: +20% higher capture efficiency, −40% charge breeding time, charge state ion production with mass over charge of 3 up to xenon and over 6 up to uranium, co-extracted contaminant density reduction by a factor 60 to 600. An 18 GHz ECR CB ion source layout is finally proposed for EURISOL.

MYRRHA [1] (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW at 352.2 MHz. This paper describes the thermal, mechanical and RF studies leading to the final design of the RF coupler. INTRODUCTION The coupler aims to transfer energy from the RF source to the accelerating cavities of the linac. It also provides a vacuum and a thermal barrier between air and the superconducting cavity while preserving its cleanliness. The coupler allows some mechanical flexibility to compensate differential thermal expansions and mechanical misalignments. As part of an ADS, the MYRRHA coupler is laid out for the highest achievable reliability. To improve the reliability, the coupler is operated well below its maximum performance (nominal power is 8 kW CW and 20 kW CW in the fault-tolerances schema [2]) and the redundancy of the diagnostics is used (example: two vacuum gauges used rather than one). DESIGN OVERVIEW The power coupler is made of three main elements (Fig. 1):  A ceramic window with an inner coax (antenna) and an outer coax (shaft) brazed on a high purity alumina ceramic,  A double input tee, with, on one side, a flange to bring RF power, and on the other side, a special short stub, to bring cooling pipes all the way up through the antenna,  A barometric compensator, to minimize mechanical load on cavity. This load is due to differential pressure between inner cryomodule pressure and atmospheric pressure. The coupler allows some mechanical flexibility to compensate differential thermal expansions and mechanical misalignments thanks to bellows. The resistance of the RF coupler submitted to various sets of operation static loads (differential pressures and connection efforts from RF bellows and compensator bellows) has been checked by using finite element simulations: substantial safety margins have been observed for all simulated configurations. The absence of modal frequency under 50 Hz has also been verified, as requested by the specifications (Fig. 2). Figure 1: Main elements of the power coupler. Figure 2: First vibration mode (antenna bending) at 72 Hz, cut view.

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

Cryomodules of the superconducting accelerator SPIRAL 2 have been successfully qualified and are now under commissioning on the linac at GANIL (France).This paper presents the successful results of the power conditioning of the couplers both on a test bench in Grenoble and during the cryomodules qualification. It also shows the influence of some factors, such as surface state and experiencing a cavity quench around the antenna, on the power conditioning process (duration, quality). (C) 2017 Elsevier B.V. All rights reserved.

We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10(-29) e cm.

The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

The French IRT-Nanoelec consortium in collaboration with GENEPI2 accelerator is offering world unique and complementary techniques for Hirel components characterisation. Part of this capability is the high and low (thermal) energy neutron testing of devices.

GENEPI2 (GEnerateur de NEutrons Pulse Intense) is an accelerator-based neutron source operating at LPSC laboratory in Grenoble (France). The neutrons are produced at 2.5MeV or 14.2MeV trough fusion reactions. GENEPI2 specifications allow performing efficiently accelerated irradiation tests of integrated circuits. This facility can also be operated to test and calibrate different types of detectors. This paper will describe the facility and its performances. Then, measurements of the neutron production will be presented as well as different types of experiments and irradiations. Finally, we describe upgrades undertaken to increase the neutron flux and optimize the facility for multiple applications.