Author: Lagniel, J.-M.
Paper Title Page
MOPOST010 Deuteron Beam Power Ramp-Up at SPIRAL2 70
 
  • A.K. Orduz, M. Di Giacomo, R. Ferdinand, J.-M. Lagniel, G. Normand
    GANIL, Caen, France
  • D.U. Uriot
    CEA-IRFU, Gif-sur-Yvette, France
 
  The SPIRAL2 linac commissioning started on 8 July 2019 after obtaining the authorisation to operate by the French Safety Authority. The tuning of the two Low Energy Beam Transport (LEBT), Radio Frequency Quadrupole (RFQ), Medium Energy Beam Transport (MEBT), Superconducting (SC) linac and High Energy Beam Transport (HEBT) was done with H+, 4He2+ and D+ beams during three periods of six months each in 2019, 2020 and 2021. The results obtained in 2021 with a D+ beam are presented. The strategy for the tuning of the MEBT, including three rebunchers, is described. The comparison between the beam parameter measurements and reference simulations are also presented. The main results of the power ramp-up to 10 kW in the linac with a 5 mA D+ beam are next reported. Finally, the extrapolation from the nominal power (200 kW) to the obtained results is analysed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST010  
About • Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022
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MOPOST038 Excitation of the σll = 90° Resonance by the Cavity RF Accelerating Fields 152
 
  • J.-M. Lagniel
    GANIL, Caen, France
 
  In RF linacs the longitudinal focusing is done by nonlinear forces and at high accelerating fields the zero-current longitudinal phase advance per longitudinal focusing period σ0ll can be high. The nonlinear components of the RF field (sextupolar, octupolar and higher order components) can then excite parametric resonances, including the 4th-order resonance (σll = 90°) when σ0ll is higher than 90°, inducing strong longitudinal emittance growths and acceptance reductions. The longitudinal beam dynamics is therefore complex, even when the nonlinear space-charge forces are ignored. The parametric resonance excitation by the RF field is analyzed before discussing the additional effect of the nonlinear space-charge forces, in particular to explain why the zero-current longitudinal phase advance per transverse focusing period σ0lt is not a relevant parameter. Examples are given in the SPIRAL2 linac case.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST038  
About • Received ※ 16 May 2022 — Accepted ※ 17 June 2022 — Issue date ※ 22 June 2022  
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