Beam studies : Space charge and resonances Longitudinal limitations E- cloud effects

1. PLANS FOR THE UPGRADE OF THE LHC INJECTORS R. Garoby, S. Gilardoni, B. Goddard, K. Hanke, M. Meddahi, M. Vretenar CERN, Geneva, Switzerland Straight section 314 315 316 317 318 319 320 321 317 314 315 316 318 319 320 321 SUMMARY The LHC injectors upgrade (LIU) project has been launched at the end of 2010 to prepare the CERN accelerator complex for reliably providing beam with the challenging characteristics required by the high luminosity LHC until at least 2030. Based on the work already started on Linac4, PS Booster, PS and SPS, the LIU project coordinates studies and implementation, and interfaces with the high luminosity LHC (HL-LHC) project which looks after the upgrade of the LHC itself, expected by the end of the present decade. The anticipated beam characteristics are described, as well as the status of the studies and the solutions envisaged for improving the injector performances. LINAC4 (Oral talk TUOAA03) ACCELERATOR EQUIPMENT SATELLITE VIEW DURING CONSTRUCTION DTL Prototype RFQ MODULE Linac2 CIVIL ENGINEERING and INFASTRUCTURE COMMISSIONING SCHEDULE Linac4 ready : April 2014 Linac4 PIMS MODULE Start of beam commissioning (3MeV): May 2013 End of beam commissioning (160 MeV): April 2014 (version November 2010) INSIDE OF SURFACE BUILDING CCDTL Prototype ACCELERATOR TUNNEL PMQ (DTL) 5 commissioning stages: (on intermediate dumps) 3 MeV 10 MeV 50 MeV 100 MeV 160 MeV PS Injector (Posters WEPS019 and 020) PS Upgrade (Posters MOPS014, WEPS018 and THPS059) Tune scans at 2 GeV • PSB Upgrade (Baseline) • H- injection at 160 MeV (instead of proton betatron stacking at 50 MeV) • New wide band RF system (based on FineMet cores) • Increase of maximum energy to 2 GeV kinetic (instead of 1.4 GeV) with new power supply • Overall consolidation/renovation of equipment (beam instrumentation etc.) • RCS option (study) • 3-fold symmetry • 4/21 of PS circumference • Beamstudies: • Space charge and resonances • Longitudinal limitations (instabilities and • imperfections of gymnastics) • E-cloudeffects • New longitudinal gymnastics • (batch compression) • Hardware developments: • Injection at 2 GeV kinetic (instead of 1.4 GeV) • Upgraded feedbacks on RF cavities • Dedicatedwide band feedback for coupledbunchinstabilitiesdamping • Overall consolidation/renovation of equipment (beam instrumentation, etc.) • Otherequipment (ongoinganalysis) Batch compression RF Voltages 120 ms ESTIMATED BEAM CHARACTERISTICS AT INJECTION IN LHC SPS Upgrade (Poster MOPC058) Suppression of e-cloud signal with clearing electrode and aC coating • Beamstudies: • Space charge and resonances • Longitudinal limitations • E-cloudeffects • New working point • Hardware developments: • Upgrade of • 200 MHz RF system • Kickers impedancereduction • New collimation system • Beam dump upgrade • aCcoating for reducing SEY of vacuum chambers • Fast transverse feedback against TMCI and e-cloudinducedinstabilities • Overall consolidation/renovation of equipment (beam instrumentation, protection systems, etc.) 50 ns bunchspacing Emittance vs intensity for single bunch on SPS Q20 (new working point) and Q26 cycle (usual working point) at 26 GeV/c Nominal performance Baseline (estimated SPS limit) Stretched: (estimatedlimit of SPS injectors) Q2/2011 Beam Parameters at 7 TeV MD: double PSB batch H/V transverse emittances [mm.mrad] • Re-shuffling of the TW cavity sections • in 6 cavities • Construction of 2 new RF power plants • rated at 800 kW CW / 1700 kW pulsed MD: single bunchwithlowgt ? ? Bunch intensity within constant longitudinal emittance [x1011 p/b] 25 ns bunchspacing Nominal performance Baseline (estimated SPS limit) Stretched: (estimatedlimit of SPS injectors) CONCLUSIONS MD: double PSB batch In the first phase of the LIU Project , until the end of 2012, the limitations in the LHC injector chain are being studied as well the means to reach beam characteristics compatible with the luminosity goals of the High Luminosity LHC during the period 2020-2030. A number of actions have already been identified as necessary in the PS-Booster, the PS and the SPS accelerators and they have started to be addressed in order to meet the project deadlines. Linac4 will be a key contributor. Its construction is already well advanced and its operation as the source of all protons at CERN is planned at the latest during the second long LHC shutdown [probably starting at the end of 2017]. Beam Parameters at 7 TeV H/V transverse emittances [mm.mrad] MD: single bunchwithlowgt ? ? Bunch intensity within constant longitudinal emittance [x1011 p/b]