Task 2: High-gradient normal-conducting technology development

1. Task 2: High-gradient normal-conducting technology development W. Wuensch EUCARD2 rf program review 18 July 2011

2. Task 2: Overall objectives • Advance high-gradient, normal-conducting rf technology through development of: • two types of high-gradient CLIC structures - main linac accelerating structures and crab cavities • high-power and beam-based X-band test infrastructure. • Spread X-band and high gradient expertise to many labs – has been concentrated at CERN/KEK/SLAC

3. Rapidly spreading X-band and high-gradient technology • Linear colliders: CLIC • Compact FELs: KVI Groningen, Trieste, Frascati, MaRIE • Compton-scattering light sources: MEGARAY • Medical accelerators: TERA, X-ray sources • Instrumentation: rf based high performance streak cameras

4. Task 2: Activity structure • CLIC main linac accelerating structures with wakefield monitors • CEA • Manchester • PSI • X-band crab cavities • Lancaster • Manchester • STFC • High-power and beam test infrastructure • CEA • PSI • (Valencia) Overall coordination: CERN

5. 4. CLIC_DDS_A Axial E-Field Surface E-Field E-field Port11 Port 2 7.5 Beam 7 Matching cell Ez (V/m x104) Es (V/m x104) 5.0 0 300 0 z (mm) 225 z (mm) • Match-out the full, tapered structure • E-field and S11 shown ~198.6mm

6. 2. Work in Progress +Future Plans Standard DDS Manifold Additional Manifold I/P at /2=15.9GHz • CLIC_DDS_A is equipped with mode launchers –aim is to demonstrate ability to sustain HP • CLIC_DDS_B includes full HOM ports • Matching the HOM coupler for CLIC_DDS_B (dipole band ~ 15.9 GHz – 18 GHz) • Construct pair of structures with full damping features • Moving to a high phase advance (HPA) structure allows other parameters to be optimised • 5/6 phase advance structure design in progress • In the HPA design further features being explored • Additional manifold (8), add SiC? Sic EnhancedCoupling Sic

7. Context of the X-band activitiesat CEA Saclay • CEA entered in the CLIC collaboration with the construction of the Probe Beam Linac CALIFES in CTF3 (in 2005) • Exceptional contribution of France to CERN • CTF3 contributions: • HV modulator and RF components for the CERN klystron test stand and TBL line • Accelerating structures for the Two Beam Test Stand • Period : 2008 – 2012, Budget = 1 M€ - 48 persons-months (p.m.) Accelerating structures (fabrication in progress) HV Modulator RF Components

8. Wakefield monitor development for CLIC accelerating structures GdfidL simulation of TM modes, beam offset dx = 1 mm • Wakefield Monitors = Beam Position Monitors integrated to the accelerating structures • Allows beam-based alignment of structures to remove wakefield effects and emittance growth • Emittance growth very well improved by aligning the structure to an accuracy of 5 µm 18 GHz DX DY • Accelerating Structure features : • TD24 (CERN design) without RF absorbers • 100 MV/m accelerating gradient • 24 tapered cells with 2/3 phase advance at 12 GHz with mean aperture of 5.5 mm • dipole mode above 16 GHz • WFM features : • WFM = Two coaxial rf pick-ups on the middle cell damping wg • on large side wg for TM-like modes • on small side wg TE-like modes Hybrid HEM modes in the cell generated by an offset beam

9. CLIC Crab Cavity R&D • CLIC-CC R&D: • Multi-cell 11.9942 GHz dipole-mode cavity developed. • Various mode damping schemes investigated: • Choke • Waveguide • An optimised 7-cell, waveguide damped design being investigated further. • LLRF R&D: • CLIC-CC and LHC-CC phase control models under development.

10. The 12 GHz Power station project at CEA Saclay • Independant operation to CTF3 • Proximity with chemical lab and clean room Specifications : RF Frequency: 12 GHz Peak power: 120 MW Pulse length: 300 ns Repetition rate: 50 Hz • Main features: • Modulator HT 430 kV • Klystron 50 MW – 1.5 µs • RF Pulse compressor SLED • LLRF withfast phase modulation Klystron Test structure area RF Pulse compressor Modulator 10

11. WP tasks • Design and fabricate multi-purpose RF Front Ends for WFM. • Should be easily adaptable to different frequencies; 15 GHz, 18 GHz, 24 GHz • Build hard-ware for CTF3 and SwissFEL injector. • Design and fabricate alternative WFM(s) for other structures • (collaboration with CERN). • 3. Test and commission the different RFFE and pick-ups with beam at CTF3 and • SwissFEL injector. Resources: Hardware: 6 RFFE ~ 120 kE; WFM ~ 80 kE. Manpower (PSI): Scientist/engineer 6 months, post-doc 2 years, technician ~ 2 years. + CERN manpower (?) Participating laboratories: CERN, PSI Infra-structures involved: CTF3, SwissFEL Injector

12. Main beam outward pick up 12 GHz Oscillator CLIC Crab High Power Distribution • Need to understand long term phase stability of the distribution scheme • Requires an experiment to measure phase transients. travelling wave cavity Laser interferometer Control Dual Output or Magic Tee Waveguide with micron-level adjustment Waveguide with micron-level adjustment LLRF LLRF Phase Shifter From oscillator 12 GHz Pulsed Klystron ( ~ 20 MW ) Pulsed Modulator Vector modulation Control main beam outward pick up

13. Broad range of participants, many activities • Extension of ongoing EUCARD activities • Recent expression of interest also by the University of Valencia

14. CERN request reduced to coordination manpower only • Roughly flattens €/lab/activity to 350-400k • Activities are stretched, posts are lost, but primary deliverables are maintained

15. Participation of certain participants in certain activities have been eliminated. • Some deliverables are eliminated • Need to ask the question whether we are below minimum worthwhile level for further participant-activities.