CEA, Gif-sur-Yvette
We review the beam dynamics basis of non-equipartitioned beams, discuss the consequences of different types of couplings on the beam stability, especially the space charge. Several multiparticle simulations and experiments are shown to illustrate these instability issues.
INFN/LNL, Legnaro (PD)
New projects like IFMIF or the new generation of Spallation Neutron Source require high power beams with high availability and reliability. To achieve these results one needs low beam losses and a good control beam dynamics. This paper focuses on the important characteristics and critical beam dynamics design issues for the high intensity linacs. In particular the techniques used for the loss control at the design stage, with the emphasis on the physical phenomena like emittance growth and halo. The reliability issue will be addressed with practical examples from the low energy and high current IFMIF-EVEDA project and comparing this case with higher energy projects.
IF-UFRGS, Porto Alegre
UFPel, Pelotas
In this paper, the dynamics of inhomogeneous high-intensity charged particles beams is investigated. While for homogeneous beams the whole system oscillates with a single frequency, any inhomogeneity leads to propagating transverse density waves which eventually result in a singular density build up, causing wave breaking and jet formation*. A theory is presented which allows to analytically calculate the time at which the wave breaking takes place. It also gives a good estimate of the time necessary for the beam to relax into the final stationary state consisting of a cold core surrounded by a halo of highly energetic particles. The halo size and emittance growth are estimated using a core-particle type analysis where the inhomogeneous core density evolution is determined based on an average Lagrangian approach**. The role of envelope mismatches in the wave breaking process is also studied. The analysis reveals that the wave breaking time is very susceptible to the mismatch; judiciously chosen mismatches can largely extend beam lifetimes***.
*Anderson, Rosenzweig, PRST AB 3, 094201 (2000); Rizzato, Pakter, Levin, Phys Plas 14, 110701 (2007).
**Nunes, Pakter, etal, Phys Plas 16, 033107 (2009).
***Souza, etal , APL 96, 141503 (2010).
IPN, Orsay
GANIL, Caen
IN2P3 IPNL, Villeurbanne
CEA, Gif-sur-Yvette
The SPIRAL2 facility at GANIL-Caen is now in its construction phase, with a project group including the participation of many French laboratories (CNRS, CEA) and international partners. The SPIRAL2 facility will be able to produce various accelerated beams at high intensities: 40 MeV Deuterons, 33 MeV Protons with intensity until 5mA and heavy ions with A/Q=3 up to 14.5MeV/u until 1mA current. We will present the final status of the high energy beam transport lines of the new facility. Various studies were performed on HEBT and beam-dump concerning beam dynamics, safety and thermo-mechanicals aspects. New experimental areas using stable beams and the cave dedicated to radioactive ion production will be presented according the scientific program.
ESS Bilbao, Bilbao
University of Warwick, Coventry
Bilbao, Faculty of Science and Technology, Bilbao
Fermilab, Batavia
STFC/RAL/ISIS, Chilton, Didcot, Oxon
ESS-Bilbao, Zamudio
Imperial College of Science and Technology, Department of Physics, London
Elytt Energy, Madrid
STFC/RAL, Chilton, Didcot, Oxon
The Proposed Multi-specimen Low Energy Transport System (LEBT) consists of a series of solenoids with tunable magnetic fields, used to match the characteristics of the beam to those imposed by the RFQ input specification. The design of the LEBT involves selecting the number of solenoids to use and their fixed positions, so that the set of fields that provides the desired matching can be found for any given conditions (different currents, input emittances, etc). In this work we present the first simulations carried out to design the Bilbao Accelerator LEBT, which were peformed using several codes (Track, GPT, Trace2D). The best configuration is discussed and evaluated in terms of the degree of matching to the RFQ input requirements.