Outcome of HBW damper Review of W. Hofle LIU-SPS HBW damper review LIU SPS Coordination,

Objectives Review to cover: Motivation, specification, performance, technology (kicker choice), milestones, deliverables, project organization, responsibilities and schedule Aim is to agree baseline for upgrade path, and to highlight potential problem areas

Specific questions for reviewers 1.Are the beam and system specifications clearly defined? If not what studies are still needed? 2.Is the system concept feasible for the required applications? 3.Can the choice of kicker technology for the final system be made now? If not, what information is still needed? 4.Is the planned development, construction and installation schedule correct (i.e. complete with all activities and deadlines, realistic, conforming to CERN's needs and fitting with collaborators' constraints)? 5.Is the project structure clearly defined, including list of deliverables and responsibilities for deliverables and studies? 6.Are the responsibilities correctly assigned, or should some be re-discussed? 7.Are there deliverables or studies which need advancing in time, for example before the LARP construction decision? 8.Is the additional impedance of the system known, and acceptable for the SPS?

Organisation Reviewers: –Gianluigi Arduini, CERN –Mike Brennan, BNL –Fritz Caspers, CERN –Rhodri Jones, CERN (Chair) –Dmitry Teytelman, DIMTEL Inc. Report: 6 pages available

Timetable

General Findings Current focus: vertical ecloud instability in SPS, no need for TMCI test bed for LHC SPS scrubbing efficiency SPS relevance for LHC: prepare doublet scrubbing beam for LHC stay flexible enough to extend to H-plane if required Strong recommendation to move to multi-bunch beams a.s.a.p. Experimental verification with multi-bunch beams before full implementation decision in 2016  Wide band kicker is highest priority: post review decision: parallel paths: strip-lines (implementation for start-up after LS1), LBL proposal TEM slotline kicker (longer lead team), Faltin type both projects within RF-PM section (E. Montesinos), staffing !

Q1 Main items for specification are BW and kick strength Need for more experimental evidence to support requirement for BW Need for more simulations to demonstrate BW required for higher energy No need for 200 MHz bunched beam, only V-plane for 25 ns Strong request to treat scrubbing doublet beam Cross talk to H-plane needs attention Simulations mainly for Q26 optics, but issue with Q20 controller design Kick strength: need for full analysis of resolution including noise  Recommendation: Open loop simulations simulations vs. energy Use ideal kicker to understand phase margins, include chromaticity Adapt FB algorithm to achieve stability at Q20 Understand 2012 demonstrator “Are the beam and system specifications clearly defined? If not what studies are still needed ?”

Q2 Yes, if simulations show that there is no need for > 1 GHz If more BW is required, consider partitioning the system Pus, strip-lines and slotted PU look feasible, common mode suppression SW and HW equalizers need to be studied Scrubbing Beam: need for demonstration during splitting process, coexistence with existing damper Injection transients !  Recommendation: Full Noise Analysis Analysis of Injection transients “Is the system concept feasible for the required applications?”

Q3 Priority: Get a high bandwidth kicker installed a.s.a.p. Parallel approach recommended: strip-lines and Faltin type Heat loss study Field uniformity Required bandwidth and kick strength “Can the choice of kicker technology for the final system be made now? If not, what information is still needed?”

Q4 (8) Slotted kicker: Z/n|| =   negligible in SPS, 10  (but not LHC) Slotted kicker transverse impedance 100 k  /m, ok (cf. 7 M  /m) Strip-lines, some estimates were presented, but needs more work (short bunches) Heating by beam is significant and needs careful consideration “Is the additional impedance of the system known, and acceptable for the SPS?”

Q5 (4) Clear time line and plan presented : Multi-Bunch 1 GHz demonstrator HW Full Function system in 2019 Need system right after LS2, no room for delays Kicker a.s.a.p. Continued support from LARP and US a concern, alternative solutions for funding need to be studied “Is the planned development, construction and installation schedule correct (i.e. complete with all activities and deadlines, realistic, conforming to CERN's needs and fitting with collaborators' constraints)?”

Q6 (5) rather well defined Fully function system deliverables need definition Need for formal collaboration agreement “Is the project structure clearly defined, including list of deliverables and responsibilities for deliverables and studies?”

Q7 (6) High level of expertise, correct mix, continue collaborating More CERN involvement in electronics design, open hardware (?) CERN engineers to help in design to be identified “Are the responsibilities correctly assigned, or should some be re- discussed?”

Q8 (7) Multi bunch demonstrator a.s.a.p. even if not perfect invaluable experimental results expected, needed to continue Kick strength and bandwidth required remains a priority “Are there deliverables or studies which need advancing in time, for example before the LARP construction decision?”

Follow-up and Action By Working Group and Web Meetings E. Montesinos agreed to take on kicker work Kicker Design Report, Draft to Brennan this week, Simulations (Headtail) to resume in October Visit SLAC in October to discuss electronics development (D. Valuch) Instrumentation for Start-up (scrubbing), need support ABP for MDs