1. Erk Jensen/CERN Many thanks to: A. Butterworth, O. Brunner, R. Calaga, S. Claudet, R. Garoby, F. Gerigk, P. Lebrun, E. Montesinos, D. Schulte, E. Shaposhnikova, I. Syratchev, M. Vretenar

2. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 20142015201620172018 IIIIIIIVIIIIIIIVIIIIIIIVIIIIIIIVIIIIIIIV Exploration Review Conceptual Design Review/re-scope Implement re-scope Design Report 13-Feb-20142 I will look here only at the Exploration Phase

3. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System During the first phase, R&D will have to identify and study different areas with potential of significant improvement separately. Some of these areas and examples of presently on-going R&D with this potential are given below. The FCC study shall co-ordinate study effort with these ongoing studies and facilitate their continuation/extension if relevant. Results of the exploration phase will be methods, concepts, demonstrators for individual sub-systems. 13-Feb-20143

4. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-20144 *) Plus 56 copper cavities (130 MV) driven by 8 klystrons Frequency352.209 MHz Number of cavities *)288 Total accelerating voltage *)3600 MV Number of klystrons *)36 Total cryomodule length817 m Cavities per klystron8 Average (nom.) power per klystron0.6 (1.3) MW Average power per cavity90 kW Circumference26.7 km Beam energy104.5 GeV Energy loss per turn3.4 GeV Beam current5 mA Synchrotron radiation power17 MW Available cooling power53 kW @ 4.5K RF system surface7 tennis courts

5. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-20145

6. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Superconducting RF Cavity technology Power couplers Cavity optimization Cryomodules Large RF Systems Availability Reliability Maintainability Operational aspects Energy Efficiency Efficient power sources Lowering cryogenic load Energy recovery? 13-Feb-20146

7. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-20147 Energy

8. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-20148

9. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-20149 cf. LEP2: 812 m cf. LHC cryoplant capacity @ 1.9 K: 18 kW Input power couplers! Gradient Active length Voltage/cavity Number of cavities Number of cryomodules Total length cryomodules Total dynamic heat load CW RF power per cavity

10. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System x 4.4 Technology x 1.6 13-Feb-201410

11. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Superconducting RF – technology (2 examples ) 3. Push coating techniques – on Cu substrate – performance reach? 4. Coating with Nb 3 Sn on Nb looks promising – note potential at 4.2 K (left) 5. New treatment techniques – N2 processing (right) Sam Posen et al. (Cornell): “Theoretical Field Limits for Multi-Layer Superconductors”, SRF 2013 Anna Grasselino et al. (FNAL): “New Insights on the Physics of RF Surface Resistance and a Cure for the Medium Field Q-Slope”, SRF 2013 MV/m 13-Feb-201411

12. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201412 Test of RF couplers (CEA) Cylindrical window Disk window Coupler development for SPL (704 MHz)

13. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Above I gave only some examples, but they demonstrate that synergy with on-going R&D for many projects world- wide is strong and desirable. 13-Feb-201413

14. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201414

15. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System I’m a non-expert, so just some personal thoughts here: Look at what has been done already (Myrrha, Eurisol, …) A model must be developed that can predict the impact of a component/subsystem failure on the overall system performance. The model must include built-in redundancy and fault tolerance on overall reliability (to allow for optimization) It must include reliable MTTF and MTTR data of components/subsystems to allow. The model must include cost (power, efficiency) of these measures to allow overall optimisation (wrong: to pay the double to avoid a 10% down-time!) One example: Solid-state power amplifiers could allow intervention during operation! 13-Feb-201415

16. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System wall plug DC klystron eff. useable RF beam loss Φ & loss minimize losses! recover waste RF power! recover beam power! 13-Feb-201416

17. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201417

18. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201418 normalized length normalized phase cavities In the input cavity, a small RF signal modulates the velocity; after some drift space, this becomes density modulation. Passive intermediate cavities improve this bunching process. In the output cavity, bunches are slowed down generating high power RF. To maximize efficiency, bunches must be made very short and dense in the output cavity. electron trajectories Input cavityOutput cavity Picture from A.Yu. Baikov et al.: “Simulation of Conditions for the Maximal Efficiency of Decimeter-Wave Klystrons”, Technical Physics Vol. 59#3, 2014

19. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201419 Igor Syratchev, CLIC Workshop 2014

20. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201420 R&D Trend: more, smaller current beamlets, o A.Yu. Baikov, O. Grushina, M. Strikhanov propose a method to further increase bunching. Their idea: “ …to achieve this, peripherals should receive much stronger relative phase shift than the core and this could happen only, if the core of the bunch experiences oscillations, whilst the peripherals approach the bunch centre monotonously. This process can be organised by using the effect of space charge forces”. They predict efficiencies in excess of 90%. o I. Guzilov: BAC (Bunching – Alignment – Collecting), The idea: introduce additional gaps to “re-align” particle trajectories A.Yu. Baikov et al.: “Simulation of Conditions for the Maximal Efficiency of Decimeter-Wave Klystrons”, Technical Physics Vol. 59#3, 2014 I. Guzilov: “BAC method of increasing efficiency”, CLIC Workshop 2014: https://indico.cern.ch/event/275412/https://indico.cern.ch/event/275412/

21. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System 13-Feb-201421 I. Syratchev: “Roadmap for CLIC high-efficiency klystron development”, CLIC Workshop 2014: https://indico.cern.ch/event/275412/https://indico.cern.ch/event/275412/

22. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Inductive Output Tube: density modulation with a grid (like a tetrode) output to a cavity (like in a klystron). IOT shorter, less gain than klystron. IOT in 70 kW class used for DVB transmitters. Klystrons reach maximum efficiency only in saturation. o Is it necessary to back-off in operation? (we did during LEP2!) IOTs (Inductive Output Tubes) may be better in this respect: 13-Feb-201422 Illustration from CPI

23. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System CPI (Communications&Power Industries) have built a 1 MW range MB IOT demonstrator 10 years ago. ESS Lund have now revived this research, jointly with CERN 13-Feb-201423 M.R.F. Jensen et al.: “Applications of High Power Induction Output Tues in High Intensity Superconducting Proton Linacs”, IVEC2013, Paris

24. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Picture shows a 100 kW installation for Linac4 (352 MHz) 100 MW may not be possible today (or at least much more expensive), but investment into R&D may pay off! Interesting feature (concerning availability, to be studied) – one may consider a module replacement while the systems continues to run at nominal performance with small built- in fault tolerance margin… 13-Feb-201424

25. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System High efficiency, high power RF generation is needed for many future accelerator projects (proton drivers for several applications, linear colliders, material test facilities) and certainly has impact beyond the accelerator community. A network called “Energy Efficiency” has started to pick up momentum inside the European Project EuCARD2, see http://eucard2.web.cern.ch/activities/wp3- energy-efficiency-enefficient http://eucard2.web.cern.ch/activities/wp3- energy-efficiency-enefficient You are invited to become part of this network! 13-Feb-201425

26. Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System Future Circular Collider Study Kick-Off Meeting, Geneva 2014 Erk Jensen 100 MW RF System The areas of R&D identified to prepare technology for the Future Circular Collider are o Superconducting RF R&D o High Efficiency RF power generation o Design of complex systems for high availability In all these areas, the R&D has large synergies with ongoing studies and projects, with which the R&D should be coordinated. 13-Feb-201426 Thank you very much!