NC and SC Structure RF and Beam Electrodynamics Roger M. Jones, Univ. Manchester/Cockcroft Inst. Wakefields and HOM beam dynamics for ILC and XFEL: SC cavity high gradient optimisation Main linac e.m. field and beam electrodynamics HOM measurements at FLASH (FP7) 2. CLIC –Collaboration on: Main linac wakes (FP7) Crab cavity (FP7) 3. HIE-ISOLDE –Collaboration with CERN colleagues on LINAC component of upgrade to REX-ISOLDE (STFC appl.) 4. LHC –FP420 Impedance measurements and RF simulations

1.2 High Precision THIRD HARMONIC SC Cavity Alignment/Diagnostics/BPM with HOM Measurements Nicoleta Baboi, Ursula van Rienen Roger M. Jones DESY, Univ. of Rostock, Univ. of Manchester/ Cockcroft Inst. EuCARD WP10.5 Task leader on HOM Distribution (inc. 3 sub-tasks) EuCARD Board member

bunch compressors bypass line gun undulators FEL beam ACC39 4 cavities within 3.9GHz Module collimator section dump 5 accelerating modules with 8 cavities each 1.3GHz SC, typically 450-700MeV, 1 nC charge for FLASH/XFEL HOMs generated in accelerating cavities must be damped. Monitored HOMs facilitate beam/cavity info Forty cavities exist at FLASH. -Couplers/cables already exist. -Electronics enable monitoring of HOMs (wideband and narrowband response). Based on 1.3 GHz (SLAC/FNAL/DESY) Diagnostics – will be redesigned for ACC39 as part of EuCARD

1.2 Response of HOM modes to beam

1.2 HOMs in SC Accelerator Cavities Schematic illustrating ALICE* Experience gained on FLASH measurements will be invaluable. HOMs in ALICE TESLA cavities will provide information on: 1. Beam position (effectively a built-in BPM) 2. Alignment of cells (and groups thereof). Schematic illustrating ALICE* CI/Univ. of Manchester PDRA I. Shinton (left) and Ph.D. student N. Juntong (right) participated in ALICE commissioning in Dec 2008

Roger M. Jones Cockcroft Institute and The University of Manchester 2. Wake Function Suppression for CLIC –A Manifold Damped and Detuned Structure Roger M. Jones Cockcroft Institute and The University of Manchester R t/2 a1 b Rc a L a a a+a1 Recent Invited Talks Recent Journal Pubs CLIC09, CERN, Oct’09 SLAC ICFA mini-ws, Sept’09 LC-ABD, DL Sept’09. XB08, CI Dec’08 R. M. Jones, Phys. Rev. ST Accel. Beams 12, 104801, 2009. R. M. Jones, et al., Phys. Rev. ST Accel. Beams 12, 051001 2009. R.M. Jones, et al., New J. Phys.11:033013,2009.

2.0 Conspectus of Measurements on DDS (inc 10MHz rms errors) DDS1 DS Qcu RDDS1 ASSET Data H60VG4SL17A/B -2 structure interleaved RDDS1 Conspectus of NLC/GLC Wake Function Prediction and Measurement (ASSET dots) Refs: 1. R.M. Jones, Phys.Rev.ST Accel. Beams, Oct.,2009. 2.R.M. Jones,et al, New J.Phys.11:033013,2009. 3. R.M. Jones et al., Phys.Rev.ST Accel. Beams 9:102001, 2006.

2.0 Driven Mode Wakefield Eqns Entails solving for eigensystem of H-Matrix. Non-linear eigenvalues solved iteratively. N-cell cavity => 3xN Matrix (N~24) 8-fold interleaved => 3xNx8 matrix Ref: R.M. Jones,et al, New J.Phys.11:033013,2009.

2.4 Concluding remarks Beam dynamics simulations needed to investigate the required tolerances. Preliminary steps, SRMS calculations, in progress (Alessandro + Vasim). Initial simulations have also been conducted on sensitivity of end-cell couplings –although this does not preclude direct insertion of damping materials. Additional optimisation also in progress on improving the Q by changing the flat-top cavity to a curved geometry –expect ~10% improvement. Some additional optimisation of cavity slots may be possible. These new designs should be verified with experimental testing of wake function (revive ASSET!) Present status –full engineering design being completed with CERN (R. Zennaro, A. Grudiev) and UMan (V. Khan, A. D’Elia) personel to facilitate fabrication in 2010 and subsequent testing at HPT andCTF3 I am pleased to acknowledge an example of a very fruitful collaboration with CERN Check this Q optimisation number… is it really 10%?? Knowledge Exchange –will present invited lectures on HOM mitigation at CERN CAS (Univ. Aarhas)

Mechanical design of preliminary structure 2.5 CLIC Crab Cavity Will exploit techniques of X-band NLC design. Initial work done on crab cavities for NLC looked into basic properties of required gradient and possible means of damping (pursued in collaboration with Univ of Lancs). CLIC crab cavity features explore experimentally and through simulations: Damping: LOMs, SOMs, HOMs. The damping requirements are stringent. Low level RF phase stability Will exploit inherent synergy between the crab cavity work and the damping in the main linac structures At this stage alternative designs are also under consideration 3. Firstly, we explore high gradient properties of the CC -7 cell demonstrator, built by Shakespeare eng., and will be tested at SLAC (Dolgashev & Tantawi) EuCARD FP7 WP 10.3.2 Leader -R.M. Jones Schematic of Crab Cavity at IP of CLIC E-fields in CLIC Crab Cavity preliminary structure Mechanical design of preliminary structure

2. X-Band Main Linac + Crab Cavity You are welcome to attend! Cement the X-band collaboration with a workshop at CI, Dec 1st – 4th 2008 Key scientists attended 80+ delegates (Europe, Asia and USA) to invited plenary and WG sessions. 44th ICFA BD sponsored workshop. All submitted papers to JACoW and several submitted papers to peer reviewed journal PRST-AB, special issue: XB08 Chair of XB08 and Editor of PRST-AB Special Issue, R. M. Jones XB 2010 will be in December 2010 at Cockcroft You are welcome to attend! http://www.cockcroft.ac.uk/events/X-Band/index.htm

High Intensity and Energy at ISOLDE 3. HIE-ISOLDE High Intensity and Energy at ISOLDE Isotope Separation On-Line (ISOL) ROH Isolde

4. LHC Low-Frequency Resistive Wall Effect Measurements Required sensitive measurement of resistive wall component of transverse impedance at low freqs (below 10 kHz) Verified theory of inductive by pass effect impedance that is decreasing at low frequencies  in disagreement with “classical thick-wall” theory Experimental verification of impedance to predict the impact of the LHC Phase I collimators on the achievable luminosity, Facilitates studies for the Phase II collimation Successful and important work! PDRA (Roncarolo) completed tenure at CI UMan/CI Ph.D. student (Day) initiated (Sept’09) his studies in this area and on kickers -working in close collaboration with F. Caspers, E. Metral, M. Barnes: LHC injection kickers transverse impedance measurements Kicker magnets for the SPS abort systems are constructed from laminated steel plates – transverse impedance measurements are needed Understanding of the limitation of existing analytical techniques for analysing beam coupling impedance t

Summary of 1, 2, 3 & 4 1. HOM characterisation of cavity wake-fields and beam dynamics for ILC/XFEL. Globalised scattering technique provides a unique method to enable trapped modes in modules to be probed. 1. HOMs as BPM diagnostic for ILC/XFEL: FP7 as part of DESY/Cockcroft/Univs Manchester & Rostock collaboration. Participating in exp program at FLASH/DESY. EuCARD FP7, R.M. Jones, Task Leader 2. CLIC structure main collaboration ongoing –ability of current design to sustain high gradients will be tested at CERN. EuCARD FP7, R.M. Jones 2. CLIC Crab cavity will be high gradient tested at SLAC. EuCARD FP7, R.M. Jones 3. HIE-ISOLDE energy upgrade ongoing. Protype quarter wave cavity built (inc. tuners). Well-reviewed by recent intl. committee. Ph.D. student –beam dynamics simulations, PDRA –cavity/coupler/tuner design. About to be sputtered with Nb. As of Nov. officially CERN designated project. Chief Scientist STFC, R.M. Jones 4. FP420 simulations/experiments morphed into ATLAS Forward Physics. Resistive wall activity continued through kicker work.

2009 Publications of  Group Journal Pubs. R. M. Jones, Wake field Suppression in High gradient linacs for lepton linear colliders, Phys. Rev. ST Accel. Beams 12, 104801, 2009, 14pp. R. M. Jones, V. A. Dolgashev, and J. W. Wang, Dispersion and energy compensation in high-gradient linacs for lepton colliders, Phys. Rev. ST Accel. Beams 12, 051001 2009, 11pp. R.M. Jones, C.E. Adolphsen, R.H. Miller, J.W. Wang , T. Higo, Influence of fabrication errors on wake function suppression in NC X-band accelerating structures for linear colliders, New J. Phys.11:033013,2009, 13pp. W. Salah, R.M. Jones, J.L. Coacolo, Analysis of space charge fields using lienard-wiechert potentials and the method of images in the RF-free electron laser photoinjectors, doi:10.1016/j.nima.2009.05.188 . W. Salah, R.M. Jones, J.L. Coacolo, Analysis of the transverse kick to beams in low-frequency photoinjectors due to wakefield effects, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 601, Issue 3, 1 April 2009, Pages 264-269 Conf. Pubs. ~ 10 conference proceedings pubs