Development of a Compact High Intensity Ion Source for Light Ions at CEA-Saclay

International audienceDuring the past 5 years, a R&D program has been launched to improve the beam quality of ECR 2.45 GHz high intensity light ion sources for high power accelerators. The main goal was to minimize the divergence and emittance growth of intense beams due to the space charge as early as possible on the low energy transfer line for a better injection in the second stage of acceleration (RFQ). This has been achieved by reducing the length of the extraction system, to be able to put the first solenoid as close as possible to the extraction aperture. This was performed with the ALISES concept (Advanced Light Ion Source Extraction System). Encouraging results have been obtained in 2012 but with limitations due to Penning discharges in the accelerating column. Taking advantages of ALISES geometry, intensive studies and simulations have been undertaken to eliminate the discharge phenomena. An Innovative and compact source geometry has been found and the source has been fabricated. This new prototype and its performances will be described, as well as magnetic field configuration studies and its influence on the extracted beam

Scintillating Screens Investigations with Proton Beams at 30 keV and 3 MeV

International audienceLuminescent screens hit by accelerated charged particle beams are commonly used as beam diagnostics to produce a visible emitted light, which can be sensed by a camera. In order to investigate the characteristics of the luminescence response of several scintillators, the beam shape and the observation of the transverse position, experiments were done with different low intensity proton beams produced by two different test benches. This study is motivated by the need to identify scintilla-tor materials for the development of a 4-dimensional emittancemeter which will allow the characterization of the beams, in particular the emittance measurement (size, angular divergence). This paper describes the experimental setups and our investigations of the optical properties of various scintillating materials at two different proton beam energies respectively about 30 keV and 3 MeV. The light produced by these screens is characterized by yield, flux of the emitted light versus the beam intensity, time response, and long life-time and they are compared

High Intensity Beam Production at CEA/Saclay For The IPHI Project

International audienceCEA/Saclay is involved in high power proton accelerators for long years. This activity started in the 90's, with the development of the SILHI source which routinely produces tens mA of proton beam. Several industrial difficulties led to a very long IPHI RFQ construction process. The 352 MHz RFQ conditioning is presently in progress. Before the completion of the conditioning in CW mode, tests with pulsed proton beam have been decided. As a consequence, the SILHI source recently produced very short H⁺ beam pulses in order to allow the first IPHI beam acceleration. Such very short pulses, in the range of few hundred microseconds, allowed analyzing the beam loading of the RFQ cavity as well as conditioning the middle energy diagnostic. This article will focus on the source parameters and beam characteristics in the low energy beam line leading to the best RFQ transmission

Beam diagnostics of an ECR ion source on LIPAc injector for prototype IFMIF beam accelerator

The IFMIF accelerator facility consists of 2 identical linacs, each accelerating a 125 mA CW deuteron beam up to the energy of 40 MeV. In order to reach these unprecedented performances, the Linear IFMIF Prototype Accelerator (LIPAc) is under installation and commissioning at the International Fusion Energy Research Centre (IFERC) in Rokkasho, Japan, in the framework of the IFMIF/EVEDA project, which is part of the Broader Approach (BA) agreement between Japan and EU. The accelerator is designed to validate components up to 125 mA CW deuteron beam at 9 MeV. The accelerator components of LIPAc have been designed and manufactured mainly by European Institutes. The injector and superconducting linac, RFQ, MEBT, Diagnostics Plate, HEBT and beam dump have been developed respectively by CEA-Saclay, INFN-Legnaro and CIEMAT-Madrid and were delivered to Rokkasho between 2013 and 2016. The commissioning of the injector with beam started in November 2014. This paper dealt with the experimental data obtained with the beam diagnostics of the injector. The electrical measurements of the beam intensity on the beam stopper were compared with calorimetric measurements. The beam profiles measured with a CCD camera and a custom image-intensified CID camera are also addressed. The analysis of beam emittance and ion species fractions from data obtained with an Allison scanner is described and the results of species fraction measurements are compared with those obtained by using a deported spectrometer. Finally, the analysis of beam space potential from data obtained with a 4-Grid analyseris presented

Increase of IPHI Beam Power at CEA Saclay

International audienceFor the first time, in April 2016, the SILHI source produced a proton beam for IPHI RFQ. Due to several technical difficulties on the RFQ water cooling skid, a short RF power pulse (100 μs at the beginning until few hundred microseconds) is injected into the RFQ accelerates the high intensity proton beam up to 3 MeV. The repetition rate is tuned between 1 and 5 Hz. Under these conditions, the beam power after the RFQ is lower than 100 W. At the end of 2017, the 352 MHz RFQ conditioning has been completed (with the same duty cycle) and the proton beam has been accelerated. The increase of the beam power is expected to continue in 2018 in order to reach several kilowatts by the end of the year. In addition, two Ionization beam Profile Monitors (IPM) developed for ESS have been tested on the deviated beam line with a very low duty cycle. The IPHI facility should demonstrate the possibility to produce neutrons with a flexible compact accelerator in the framework of the SONATE project. This paper presents the status of the IPHI project in April 2018

Intermediate Commissioning Results of the Required 140 mA/100 keV CW D⁺ ECR Injector of LIPAc, IFMIF's Prototype

International audienceThe LIPAc accelerator aims to operate in Rokkasho Fusion Institute a 125 mA/CW deuteron beam at 9 MeV to validate the concept of IFMIF's accelerators that will operate in CW 125 mA at 40 MeV. The 2.45 GHz ECR injector developed by CEA-Saclay is designed to deliver 140 mA/100 keV CW D⁺ beam with 99% D⁺ fraction ratio. Its LEBT relies on a dual solenoid focusing system to transport and match the beam into the RFQ. The normalized RMS emittance at the RFQ injection cone is required to be within 0.25π mm·mrad to allow 96% transmission through the 9.81 m long RFQ. An equal perveance H⁺ beam of half current and half energy as nominal with D⁺ is used to avoid activation during commissioning. The injector commissioning at Rokkasho is divided into three phases to characterize the emittance between the two solenoids of the LEBT (A1) and just downstream the RFQ injection cone (A2) and the extraction system of the source (A3). Phase A1 has been achieved and phase A2 continues in 2016 in order to reach the required beam parameters and to match the beam into the RFQ. This paper reports the commissioning results of phase A1 and the intermediate ones of phase A2 for H⁺ and D⁺ beams

SEPAGE: a proton-ion-electron spectrometer for LMJ-PETAL

International audienceThe SEPAGE spectrometer (Spectromètre Electrons Protons A Grandes Energies) was realized within the PETAL+ project funded by the French ANR (French National Agency for Research). This plasma diagnostic, installed on the LMJ-PETAL laser facility, is dedicated to the measurement of charged particle energy spectra generated by experiments using PETAL (PETawatt Aquitaine Laser). SEPAGE is inserted inside the 10-meter diameter LMJ experimental chamber with a SID (Diagnostic Insertion System) in order to be close enough to the target. It is composed of two Thomson Parabola measuring ion spectra and more particularly proton spectra ranging from 0.1 to 20 MeV and from 8 to 200 MeV for the low and high energy channels respectively. The electron spectrum is also measured with an energy range between 0.1 and 150 MeV. The front part of the diagnostic carries a film stack that can be placed as close as 100 mm from the target center chamber. This stack allows a spatial and spectral characterization of the entire proton beam. It can also be used to realize proton radiographies

Deuteron Beam Commissioning of the Linear IFMIF Prototype Accelerator Source and LEBT

The Linear IFMIF Prototype Accelerator aims to operate in Rokkasho Fusion Institute a 125 mA/cw deuteron beam at 9 MeV In order to prove the technical feasibility of the IFMIF accelerators concept. A 2.45 GHz ECR ion source developed by CEA-Saclay is designed to deliver 140 mA/100 keV CW D + beam. The low energy beam transfer line (LEBT) relies on a dual solenoid focusing system to transport and match the beam into the next accelerating section which is a Radio-Frequency Quadrupole (RFQ). At the end of the LEBT, the normalized RMS emittance has to be lower than 0.3π mm.mrad in order to reach the optimal beam transmission through the RFQ. This contribution will present the different commissioning phases of LIPAC ion source and LEBT. The experimental results that have been obtained will be reported. In particular, beam emittance measurements as a function of ion source extraction voltage gaps, total extracted current from the source and solenoid tunings will be showed. In order to model as well as possible the beam transport thought LEBT, intensive beam dynamics simulations that take into account space charge compensation have been performed using a self-consistent particle-in-cell code. Simulation results will be discussed and compared to experimental data

ESS nBLM: Beam Loss Monitors based on Fast Neutron Detection

International audienceA new type of Beam Loss Monitor (BLM) system is being developed for use in the European Spallation Source (ESS) linac, primarily aiming to cover the low energy part (proton energies between 3-100 MeV). In this region of the linac, typical BLM detectors based on charged particle detection (i.e. Ionization Cham-bers) are not appropriate because the expected particle fields will be dominated by neutrons and photons. Another issue is the photon background due to the RF cavities, which is mainly due to field emission from the electrons from the cavity walls, resulting in brems-strahlung photons. The idea for the ESS neutron sensi-tive BLM system (ESS nBLM) is to use Micromegas detectors specially designed to be sensitive to fast neutrons and insensitive to low energy photons (X and gammas). In addition, the detectors must be insensitive to thermal neutrons, because those neutrons may not be directly correlated to beam losses. The appropriate configuration of the Micromegas operating conditions will allow excellent timing, intrinsic photon back-ground suppression and individual neutron counting, extending thus the dynamic range to very low particle fluxes