Conversion of weighted macro-particle distributions

International audienceThis article introduces a method for adjusting macro-particle weights within a particle distribution while preserving statistical and physical properties. The method allows the weights of the new macro-particle distribution to be determined by any continuous function, including uniform. Computational simulations validate the presented approach

A Space-charge Compatible "Tomography" of Beam Phase-space Distributions

The well-known 3-gradient method allows accessing to a beam RMS emittance and Twiss parameters at a position A by measuring its rms size at a downstream position B with at least 3 different transport conditions from A to B. We suggest extending this method to access to a beam phase-space distribution model at A from beam profiles measured at B. We propose to use an iterative method which consists in: - defining a parametric model describing the beam distribution in 4D transverse phase-space at a position A, - adjusting iteratively the model parameters by minimizing the difference between beam profiles measured at B and these obtained by transporting the beam generated according to the model with TraceWIN code from A to B. This method allows taking into account space-charge and other transport non-linearities

Study on the Multipactor Barriers of the SARAF-Phase 2 Low-Beta and High-Beta Superconducting Cavities

International audienceCEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5 mA beam of either protons from 1.3 MeV to 35 MeV or deuterons from 2.6 MeV to 40 MeV. The SCL contains 13 half-wave resonator (HWR) low beta cavities (β= 0.09) at 176 MHz and 14 HWR high-beta cavities (β = 0.18) at 176 MHz. The low-beta and high-beta series were qualified in 2021 and 2022 respectively. This contribution will focus on the observation of the multipactor barriers for all cavi-ties. It will present series of data obtained during the conditioning of these cavitie

A Space Charge Compensation Study of Low Energy Hydrogen Ion Beams

High-power accelerators are being studied for several projects including accelerator driven neutron or neutrino sources. The low energy part of these facilities has to be carefully optimized to match the beam requirements of the higher energy parts. The complexity of high intensity beam dynamics in the low energy line is essentially due to the non-linear space charge effects. The PIC code CARTAGO* has been developed in order to simulate the beam transport at low energy including the temporal evolution effects of the space charge compensation. This paper relates the structure and the numerical methods of a 2D (r,z) new version of the code. The effects of the longitudinal space charge, the image charge and external 2D (r,z) magnetic field were included. The results of H

Final Design of the Fully Equipped HWR Cavities for SARAF

International audienceSNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the superconducting linac (SARAF-LINAC Project). The SCL is made up of 4 cryomodules: the first two will host each 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz; the last two will host each 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The fully equipped cavity includes the niobium cavity with a helium tank, an input power couplers and a frequency tuning system. The final RF design of the low and high beta cavities will be presented in this poster, as well as the RF design of the couplers, the expected tuning range of the cavities and the multipactor analysis

Beam Dynamic Studies for the SARAF MEBT and SC Linac

International audienceThe SARAF MEBT and Super Conducting Linac (SCL) transport and accelerate deuterons or protons from the RFQ to the final energy. In this report, beam dynamics studies for this section are described. A rational distribution of the different roles of the MEBT leads to defining its necessary quadrupole/rebuncher composition. This allows easy beam re-tuning following changes from the RFQ or the SC Linac. After observing evidences of beam losses mainly due to phase unhooking, efforts have been dedicated to enlarge the SCL longitudinal acceptance. A combination of cavity field phases is found so that the required final beam energy is also fulfilled

Mechanical Design of the HWR Cavities for the SARAF SRF LINAC

International audienceSNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the superconducting linac (SARAF-LINAC Project). The SCL consists in 4 cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz. The last two identical cryomodules will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The fully equipped cavity includes the niobium cavity with its helium tank, the couplers and the frequency tuning system. In this paper, the mechanical design and the foreseen qualification procedures for both cavities and tuning systems are presented with compliance, to the best extent, to the rules of Unfired Pressure Vessels NF-EN 13445 (1-5) standards

Strategy of Beam Tuning Implementation for the SARAF MEBT and SC Linac

International audienceBeam dynamics of the MEBT and Superconducting Linac in the SARAF accelerator are being finalized. A strategy for beam tuning implementation is applied to this section, leading to specifying the complete set of error tolerances / beam measurements / correctors. A systematic and precise methodology in several steps is applied, leading to fairly distributing the error budget, from which correction schemes are studied, allowing to determine the necessary beam measurements and correctors

Space Charge Compensation in Low Energy Beam Lines

International audienceThe dynamics of a high intensity beam with low energy is governed by its space-charge forces which may be responsible of emittance growth and halo formation due to their non-linearity. In a low energy beam transport (LEBT) line of a linear accelerator, the propagation of a charged beam with low energy causes the production of secondary particles created by the interaction between the beam and the background gas present in the accelerator tube. This phenomenon called space-charge compensation is difficult to characterize analitically. In order to obtain some quantitative to characterize the space-charge compensation (or neutralization), numerical simulations using a 3D PIC code have been implemented

Status of the uTCA Digital LLRF design for SARAF Phase II

International audienceOne of the crucial control systems of any particle ac-celerator is the Low-Level Radio Frequency (LLRF). The purpose of a LLRF is to control the amplitude and phase of the field inside the accelerating cavity. The LLRF is a subsystem of the CEA (Commissariat à l’Energie Atomique) control domain for the SARAF-LINAC (Soreq Applied Research Accelerator Facility ’ Linear Accelera-tor) instrumentation and Seven Solutions has designed, developed, manufactured, and tested the system based on CEA technical specifications. The final version of this digital LLRF will be installed in the SARAF accelerator in Israel at the end of 2021. The architecture, design, and development as well as the performance of the LLRF system will be presented in this paper. The benefits of the proposed architecture and the first results will be shown