Summary on the Contributions to Low Emittance Ring Technology

1. Summary on the Contributions to Low Emittance Ring Technology Peter Kuske, HZB and Humboldt-Innovation GmbH 7th Low Emittance Rings Workshop, 15-17 January 2018, CERN

2. 7th Low Emittance Ring Workshop Vacuum System for the FCC-ee R. Kersevan, CERN-TE-VSC-VSM Agenda: Introduction FCC-ee parameter list SR spectra, photon flux and power densities Vacuum specifications Vacuum chamber geometries: different options and SR ray-tracing Pumping system options: pressure profiles Considerations about background in the interaction region Polarization wigglers Other vacuum components Conclusions and future work

3. Conclusions and future work towards CDR • We propose to base the design of the vacuum system of FCC-ee on an adaptation of the design of the SuperKEKB storage rings; • We scale down the dimensions of that chamber in order to fit our arc magnets apertures; • We propose to install a large number of tapered SR photon absorbers, capable of covering the whole horizontal angle, masking flanges, gate valves and other components; • We propose to adapt the design of bellows and RF contact bridges, including those of gate valves, to the “comb-type” developed at SuperKEKB; • The vacuum chamber material of choice should be copper, rather than aluminium, in view of the its superior opacity to high-energy photons, and related radioprotection and R2E issues (see presentation of F. Cerutti at FCC Kick-off Meeting, 2014); • In order to guarantee a reasonably short vacuum commissioning time, we suggest installing distributed “stacked” NEG-strip pumps along the internal winglet of the vacuum chamber (especially if NEG-coating is really ruled out); • We are designing and building a ~2m-long prototype to be inserted inside of the dipole/quadrupole prototypes of A. Milanese; • We need to decide which e-cloud mitigation technology we want to adopt: NEG-coating? TiN? a-carbon? Grooved surfaces? Some combination of them? (see also M. Ady’s PhD thesis, Ch.3); • We need to pass the information to the FLUKA team so that they can calculate the amount of radiation leaked out of the vacuum chamber (meeting scheduled for this week); • We need to define a reasonable vacuum sectoring strategy in the tunnel, which could affect the installation and operation phases (e.g. bake-out, NEG-strip re-activation); • Further work on the MDI vacuum chamber geometry and pumping; • THANKS FOR YOUR ATTENTION!

4. Progress in NEG Coatings for Particle Accelerators O.B. Malyshev and R. Valizadeh, ASTeC Vacuum Science Group, STFC Daresbury Laboratory, UK 7th Low Emittance Rings Workshop 15-17 January 2018 CERN, Geneva, Switzerland

5. Conclusions • NEG coating is a technology that allows to meet UHV/XHV vacuum specification win long narrow vacuum chambers. • PSD and ESD After NEG activation at 180°C the initial(316LN)/(Ti-Zr-V) = • =20 for H2, =1000 for CH4 and =200 for CO. • Vacuum firing => an order of magnitude lower ESD • (Ti-Zr-Hf-V) < (Ti-Zr-V). • Best results is for the dense and dual layer NEG activated at 180 C • Often the only vacuum solution • Lower cost of pumping system • NEG film requires activation at 150-180 C in stead of 250-300 C usual bakeout: • Shorter bellows or less number of bellows • Wider choice of material for vacuum chamber and components • SR (or electron bombardment) induced activation/pumping: • NEG can be (re-)activated by irradiation/bombardment • NEG can pump CH4 molecules during irradiation/bombardment • The bulk conductivity: • 𝜎𝑑 = 1.4×104 𝑆/𝑚 for the columnar NEG coating • 𝜎𝑑 = 8×105 𝑆/𝑚 for the dense NEG coating • SEY < 1.1 can be obtained after activation or by conditioning

6. Detection of Cherenkov Diffraction Radiation on the Cornell Electron Storage Ring M. Bergamaschi1, V.V. Bleko2, M. Billing3, L. Bobb4, J. Conway3, R. Kieffer1,A.S. Konkov2 P. Karataev5, R.O. Jones1, T. Lefevre1, J.S. Markova2, S. Mazzoni1, Y. Padilla Fuentes3, A.P. Potylitsyn2, J. Shanks3 1. CERN, Geneva, Switzerland2. Tomsk Polytechnic University, Tomsk, Russia3. Cornell University, Ithaca, New York, USA4. Diamond Light Source, Oxfordshire, United Kingdom5. John Adams Institute at Royal Holloway, University of London, Egham, United Kingdom

7. Conclusions • Incoherent Cherenkov Diffraction Radiation looks promising for Beam diagnostic applications on both high-energy leptons and hadrons • After CESR, several beam tests prepared at CERN/CLEAR and possibly at KEK/ATF2 and Diamond in order to continue the R&D • Optimisation of the radiator geometry for a given application • Best shape/configuration for light extraction and polarization selection • Motivation to study the Beam dynamic involved in the emission of ChDR • ChDR is the emission of wakefield in a dielectric materiel • Coherent and incoherent emissions should lead to very different beam dynamic effects • Some work on-going on the simulation/theoretical sides (Tomsk Univ.) • Simulations of coherent ChDR is being studied with codes such as Particle studio, Magic or Vsim for different applications (Dielectric acceleration and THz source) RESOLUTION? T. Lefevre, LER 2018, CERN

8. Ideal Orbit Feedback for Ultra-low Emittance Rings Guenther Rehm 7th Low Emittance Ring Workshop CERN, 15-17 Jan 2018

9. How to build the ideal fast orbit feedback • Keep tunes as close to half integer as possible • Reduce excitation as far as possible (foundation, girders, water cooling) • Estimate, calculate and measure bandwidth and latency of all components • Choose fastest transport network on the market (10+Gb/s) • Choose BPMs with high sample rate (100-200kS/s, or turn-by-turn) • Bring all data to one compute node with enough power • If it saves much time, repeat computations in many locations • Implement modern control on DSP or FPGA, keep maintenance in mind • Distribute corrector data through same or similar network • Use power convertors designed, built and tested for bandwidth and low latency • Use fast corrector magnets (laminated or ferrite) over thin, low conductivity vessels (thin stainless or Inconel) to reduce eddy currents • If not all correctors can be fast, modern control algorithms can deal with that in one calculation • Finally, low synchrotron frequency might cause interaction with RF cavity feedback! 7th Low Emittance Workshop, CERN, 15-17 Jan 2018: Ideal Orbit Feedback for Low Emittance Rings, G. Rehm

10. AnnouncementTopical Workshop on Diagnostics for Ultra Low Emittance Rings (TW-DULER) Supported by the ARIES European project, under the Ring with Ultra Low Emittance (RULE) work package coordination: Synchrotron SOLEIL and Diamond Light Source are organizing a: Topical Workshop on Diagnostics for Ultra Low Emittance Rings 19-20 April 2018 Diamond Light Source Scientific Program Committee: L. Nadolski (Synchrotron SOLEIL) N. Hubert (Synchrotron SOLEIL) R. Bartolini (Diamond Light Source) G. Rehm (Diamond Light Source) B. Hettel (APS) H. Schmickler (CERN) J. Urakawa (KEK) P. Kuske (Bessy) A. Andersson (Max-IV)

11. High efficiency klystron technology. I. Syratchev, CERN High Efficiency International klystron activity 2 J. CAI, CERN Z. L. Liu, CERN C. Marrelli, ESS A. Baikov, MUFA D. Constable, Lancaster U V. Hill, Lancaster U G. Burt, Lancaster U B. Weatherford, SLAC A. Leggieri, Thales 2 Since 2013

12. Power conversion efficiency. Limiting factors. Summary. In a low perveance tube, the accumulated effect of all the limiting factors that are inherent to the bunching and deceleration processes may results in 10% efficiency reduction (from 90% to 80%). 90% FCC CSM 80%

13. Thanks for your attention! I hope I was efficient. State of the art New bunching technologies Optimised at CERN Recommended by industry

14. DESIGN AND TESTS OF EXTRACTION KICKER SYSTEM C. Belver-Aguilar, J. Holma, M. Barnes (CERN) Acknowledgement to M. Pont and N. Ayala (ALBA)

15. 8. Summary • Beam extraction from the DRs will be done by fast kicker systems: striplines + inductive adders. • Many design and optimization studies have been done on the striplines, as well as laboratory tests. • A transient study of the magnetic field as well as a review of the dipolar component of the horizontal impedance of the striplines has been done and well understood. • The striplines have been installed at ALBA, and after conditioning of the machine, beam measurements will be carried out. • Beam impedance measurements will be start soon. • Field homogeneity measurements are waiting for the filter manufacturing. • The complete extraction kicker system (striplines + inductive adders) might be tested at ALBA during this year. 17/01/2018 LER’18 21/21 10/10

16. drhgfdjhngngfmhgmghmghjmghfmf LERW2018, CERN, January 17, 2018 Yury Ivanyushenkov Advanced Photon Source Argonne National Laboratory On behalf of APS SCU team: J. Fuerst, K. Harkay, Q. Hasse, M. Kasa, I. Kesgin, Y. Shiroyanagi, D. Skiadopoulos, M. Smith, E. Trakhtenberg, and E. Gluskin Summary of activities on superconducting undulators at the APS and plans for APS-Upgrade

17. The first APS superconducting undulator, SCU0, was removed from the APS storage ring after 3.5 years of successful operation. • Two SCUs – SCU18-1 and SCU18-2 – are currently in operation at the APS. • New helical SCU is installed on the APS ring. • A concept of an arbitrary polarizing undulator, SCAPE, has been developed and will be tested in a prototype. • Scope of SCUs for APS-U is defined. • Design of the first APS-U SCU is in progress.