1. PSI, Zurich February 29 – March 2 2016 Session classification : Accelerator Concepts Tuesday, March 1, 2016 Summary Vyacheslav Yakovlev Fermilab, USA

2. Outline: The goal of the session: - Efficiency drivers for different types of the proton drivers - Wall-plug efficiency limits for the MW-range proton driver - The ways of the efficiency improvement - New technologies should be developed for this. Proton Drivers: - GeV-energy range - MW-power range - Applications: neutrinos, muons, neutrons, ADS. Types of accelerators for proton drivers: - Cyclotrons and Fixed-Field Alternating Gradient accelerators (FFAG); - Rapid Cycle Synchrotrons (RCS); - High intensity pulsed linear accelerators; - CW Superconducting RF linear accelerators. 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary2

3. Outline: Operating Accelerators: -Cyclotron (High Intensity Proton Accelerator Facility PSI) -SRF Linac (Spallation Neutron Source, ORNL) -RCS (Japan Proton Accelerator Research Complex, J-PARC) Efficiency drivers: - RF source efficiency; - Acceleration Efficiency; - Magnet system; - Cooling and/or refrigeration system; - Auxiliary systems; - Other 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary3

4. Session Schedule: 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary4

5. Operating Accelerators 1.Cyclotron, Joachim Grillenberger (PSI) 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary5 Ring Cyclotron:590 MeV 2.4 mA 186 turns 8 sector magnets R in = 2.1 m

6. Operating Accelerators, PSI Cyclotron, J. Grillenberger 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary6 Efficiency 13%

7. Operating Accelerators 2. SRF Linac, Sang-Ho Kim (SNS) 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary7

8. Operating Accelerators, SNS SRF linac, San-Ho Kim 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary8 LINAC efficiency is 8.6%

9. Operating Accelerators, SNS SRF linac, San-Ho Kim 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary9

10. Operating Accelerators 3. RCS, 3 GeV. Masahito Yoshii (JPARC) 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary10

11. Operating Accelerators, 3 GeV RCS, Masahito Yoshii (JPARC) 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary11 Efficiency 1.5%

12. FFAG, Shinji Machida (Rutherford Appleton Lab) 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary12 Ultimate circular accelerators should minimize electricity for the lattice magnets. DC operation with superconducting magnets or permanent magnets. Linear and circular accelerators do not make any difference in terms of energy efficiency when the most of electricity goes into the RF cavities. Is this true statement? Fixed Field Alternating Gradient (FFAG) accelerators have several advantages. Use DC magnets and energy can be over 1 GeV (advantage against cyclotron). Time structure of output beam can be controlled because it is like a linac and storage ring together (advantage against linac). But needs R&Ds and demonstration. FFAG optimized as a few GeV proton driver is discussed. Combination of conventional spiral and radial sector machines. We are making a 10 years R&D plan right now. To be recognized as a member of accelerators for user operations.

13. Discussion 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary13 Topics: 1.What are the efficiency drivers for different types of accelerators? 2. In order to produce the same amount of beam power, say 1 MW, which accelerator: linear and circular, needs more electric power in the accelerating cavity? 3.What new technologies should be developed in order to improve the efficiency? 4.How much it is possible to improve the efficiency?

14. Discussion 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary14 Efficiency is not a primary parameter, it is determined and limited by -applications of the accelerator; -accelerator parameter range. It makes sense to compare efficiency of the accelerators only for the same application and for the same basic parameters. Improvements of the efficiency are specific for exact accelerator design.

15. Observations 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary15 In considered range of parameters (1.4 MW, ~0.6 GeV) cyclotron demonstrates high efficiency, ~13%. For higher power efficiency is even better. The cyclotron having 10 MW at 1 GeV is feasible. Pulsed SRF linac demonstrates high efficiency, up to ~20% at 1.4 MW, 1 GeV (RT machine for the same parameters has ~7%). There is a room for further improvement. The efficiency is a function of various parameters such as pulse repetition rate, beam duty, and beam loading. Efficiency of entire SNS linac (including RT low energy part) is 8.3%. RCS provides very high power, 1 MW at 3 GeV.

16. R&D recommendations 3/1/2016Vyacheslav Yakovlev. Session classification : Accelerator Concepts. Summary16 Further development of existing types of accelerators and related technology in order to reach higher efficiency: -Cyclotrons; -SRF linacs; -RSCs Related technology: -SC (including (HTS) and permanent magnets; -SRF and RT cavities with low losses ( including high Q0 for SRF); -Capacity energy storage for synchrotron magnets. New or alternative ideas and approaches should be developed for both new and explored basic accelerator parameters -FFAG; -Other new ideas. RF is an important efficiency driver for all the considered accelerators. New high - efficiency RF sources and operation techniques should be developed: -magnetrons, -phase modulation, -high-efficiency klystrons.