Proposed Joint Research Activity at DESY in Frame of FP7 Status October 2006 .

1. Proposed Joint Research Activity at DESY in Frame of FP7 Status October 2006. General Remark JRA at DESY has been meant as R&D program for the performance improvement of two existing facilities at DESY: 1. TTF-II / FLASH 2. Cryomodule Test Bed (CMTB). All achievements can be later implemented in the European XFEL and other FEL facilities in Europe and World-wide Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

2. Topics and Implementations Summary of SRF WPs proposed at DESY Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

3. Countries and Institutions Summary of SRF WPs proposed at DESY Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

4. Costs and FTEs Summary of SRF WPs proposed at DESY, cont Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

5. 1. Superconducting RF gun Motivation SCR-gun operating in continuous wave (cw) or near-cw mode, which does not exist at present, will  allow for much higher number of bunches generated per second and will increase average brilliance of many FEL facilities driven by the superconducting accelerators. Technology differs from other approaches Bulk niobium 1.5-cell cavity with arc deposited emitting spot of lead, which is very good superconductor. Use of superconducting photo-cathode simplifies construction of the cavity which operate with very long life time cathode. Encouraging results of Quantum Efficiency tests and RF-tests of half cell with the lead spot have been published by the applying Collaboration. Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

6. 1. Superconducting RF gun What should be done in the frame of work package Cavities, Auxiliaries and Preparations Fabrication of  two Nb prototypes of the 1.5-cell  RF-gun cavity Preparation and  cryogenic  testing of  cavities Cavity transport costs    (round trip INS-DESY)                                         RF- modeling cost (SLAC- sub partner) Cryostat Tuner Input Coupler : Apparatus for coating which will be added to the existing setup Ultra high vacuum Turbo pump Valve Leak detector  Power supplier for arc discharging  Laser initializing the arc  Clean Room Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

7. 2. CW operating transmitter Motivation RF power source operating in cw and pulse mode enabling substantial increase of the duty factor of FEL driving sc linacs. A prototype should be built in the frame of FP7. Industrial studies of the Inductive Output Tube are now conducted in the frame of the EUROFEL 32 kW 1300 MHZ IOT Preliminary parameters of 120 kW IOT (Modeling by H. Bohlen) New R&D Upgrade of the existing tube Courtesy of CPI : H. Bohlen, Y. Li and P. Krzeminski Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

8. 2. CW operating transmitter • What should be done in the frame of work package • Components to be built • 1. IOT with upgraded output power to 60 kW or if technically possible to 120 kW • 2. Driving amplifier ~1 kW • 3. Power supply -170 kW • 4. Electronics for operation control and protection • : • High power test components to be purchased (commercially available) • Waveguides • Directional couplers • Circulators • Loads Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

9. 3. LLRF controls Motivation Advance RF Control Technology in the areas of hardware and software to meet the requirements for FLASH and European XFEL. What should be done in the frame of work package 1. Develop LLRF implementation as HA ATCA System 2. Develop concept for modular system 3. Develop multi-channel ASIC version of downconverter 4. Develop multi-channel downconverter board based on ASIC to standard component 5. High degree of automation for large scale system, operability 6. Reliability and availability optimization and cost reduction 7. Technical performance, pushing the envelope of performance Sub-tasks 1.  HA  (High Availability) LLRF Implementation in ATCA The demand for high availability, modularity, standardization and long time support favors the choice of the ATCA and TCA standard with carrier boards and AMC modules. This technology is basis for the ILC technical design. Presently none of the required AMC boards for ADCs, DACs, downconverters, clock synthesizers etc. are available. Therefore a development of these boards using state-of-the-art technology is necessary.   Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

10. 3. LLRF controls Sub-tasks, cont. 2. High precision Timing and Synchronization for LLRF Precision timing signals in form of clocks and event triggers are required for digital control system to guarantee synchronicity of ADC data with the electron bunches and allow for digital RF field detection. The clock signals are in the 100 MHz range require stabilities of the order of a few picoseconds. Also available must be RF reference signals as local oscillator signals for downconverters and as RF calibration signals with a  long stability of the order of 100 femtoseconds. Although the development of system components is quite advanced, it will be necessary to integrate all this systems for accelerator operation. 3. Software Architecture and Implementation Strategies The performance and  functionality of the digital RF control system is largely dominated by the implemented software. For the LLRF system for the XFEL about 50% of the LLRF system cost will be invested in software. Most future upgrades will be made in software. It is therefore essential to define a software architecture which is modular and allow collaborator to contribute from their home institutes. In an early stage the distribution of algorithm should be specified to determine the necessary resources (FPGA, DSP, CPU). 4.  Precision RF Field Measurement Achieving an RF field stability of the order of 2e-4 for amplitude and 0.01 deg. requires highly stable field detectors. Different approaches for low noise and low drift must be combined to achieve the required short and long term stability. Precision detection of single bunch induced transients is necessary to determine the beam phase without risk of vacuum loss and beamline activation. Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

11. 3. LLRF controls Sub-tasks, cont.. 5. Commissioning and Operation Procedures The knowledge of commissioning and operation procedures is necessary to develop the required applications. These are used to automate the operational procedures. A cavity simulator is required for the development of the LLRF electronics and to allow only debugging of hardware and software.6.  Interfacing to other accelerator subsystems In accelerator design the interfaces between various subsystem are crucial for successful operation but are usually not specified very well. It is therefore necessary to study the requirements and implementation for these interface in great detail. 7.  Fast Frequency tuner Fast frequency tuners are necessary for Lorentz force compensation. Their potential for control of microphonics and the possibility of using time varying detuning to increase the acceptable gradient spread require further investigation. 8.   Beam feedbacks Beam based feedbacks are necessary to correct long term drift of RF amplitude and phase in RF gun, injector and main linac. The concepts for the beam based feedback must be developed and prototype implementations evaluated at the ‘FLASH’. Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

12. 4. Timing & synchronization for SC FEL For FELs: Only way towards fs with external seed laser! Femtosecond optical link Manipulation laser Pump-probe laser Photo-cathode laser compressor RF gun undulator  Booster Acc. module Introduces unavoidable timing jitter ~ 30-60fs Motivation Synchronization on sub-femtosecond time scale especially for all kind of pump-probe experiments Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

13. 4. Timing & synchronization for SC FEL High repetition rate high power ultra-broadband laser Based on Cavity enhanced Optical Parametric Chirped Pulse Amplification Cryogenic cooled Yb:YAG ~ 200W Burst pulse mode Octave spanning 100MHz, Ti:Sa CW optical standard frep • P > kW • f = 1MHz (1ms) • = 0.8/2um T = 5fs/14fs fceo f-2f DFG CEO stabilization + locking to optical standard Stretcher ~ 50ps + high resolution Dazzler Passive pump power enhancement cavity Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

14. 4. Timing & synchronization for SC FEL What should be done in the frame of work package • Synchronization on sub-femtosecond time scale, which requires: • 1. Seed or manipulation laser acting on sub-ensemble of the electron beam • 2. FEL production mechanism: • HHG short wave length seeding (7-30fs, 10-60nm) FLASH • Long wave length energy modulation (=10um) FLASH • Two-cycle laser slicing XFEL • Short wavelength energy modulation ( =0.8um, ESASE) XFEL • 3. Necessary requirement: • Electron beam is synchronized to laser < t ~ 30-60 fs • Manipulation laser to exp. laser on (sub-)femtosecond level • High repetition rate ~ 1MHz • Compatibility to electron beam time structure to avoid jitter due to vibration and diffuse ground motion (<1kHz, 30nm = 100as) • 4. Laser to laser synchronization (much higher precision possible): • Fceo stabilized link • Optical-clocks for low frequency phase noise stabilization Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

15. 5. Large grain / single crystal Nb resonators Motivation Big grain or single crystal niobium sheets which are cut directly from ingot are less expensive in the cavity production (no rolling needed) and preparation (BCP instead of EP chemical treatment) Cavities made of that material have very smooth surface. This increases threshold of the field electron emission and potentially leads to higher quality factor and lower cryogenic load. Large grain ingot. Diameter ca. 300 mm Disc for a half cell Grain boundaries (GB) lower cavity performance: cause magnetic field enhancement (steps on GBs after BCP), make easier the penetration of external magnetic field (GBs are planar weak links with reduced critical current density), increase RF resistance due to vortices penetrating along the grain boundary (reduce the quality factor Qo), make easier the hydrogen absorption and diffusion, gather impurities (reduced RRR), reduce the thermal conductivity at low temperatures (reduced phonon contribution), reduce the accuracy of the half cell shape by deep drawing (steps on grain boundaries), possibly make worse the baking (oxides and impurities in grain boundaries), possibly make worse high pressure water rinsing (enhance the surface roughness) Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

16. 5. Large grain / single crystal Nb resonators What should be done in the frame of work package • Large Grain Niobium (LGN): • Fabrication, preparation (BCP compare to EP) and RF tests of single cell/nine cell cavities from • LGN of different suppliers. • Investigation of centrifugal barrel polishing (tumbling) influence on LGN cavity performance • Investigation of the deep drawing peculiarities and shape accuracy in LGN cavities. • Single Crystal Niobium (SCN): • Fabrication, preparation (BCP compare to EP) and RF tests of single cell/ nine cell 1.3/3.9 GHz • cavities from SCN • Investigation of the influence of SCN orientation on cavity performance with the aim to define the • optimal orientation • Investigation of the SCN orientation influence on electrical, magnetic, thermal, mechanical • properties • Investigation of the surface layers covered differently oriented SCN and those influence on the • baking procedure • Investigation of electron beam welding conditions, deformation degree and annealing parameters • in order to define the conditions allowing not destroy the SCN Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

17. 6. Improvement of the 3.9 GHz higher harmonic system Motivation Linearization of the bunch phase-space for lower longitudinal emittance and better bunch compression. What should be done in the frame of work package FLASH will have 1 module with four 9-cell 3.9 GHz cavities manufactured and processed at FNAL, Approx. 36 Cavities needed for the European XFEL. This is too much to be processed at FNAL. Processing and testing facilities are required at DESY. • Extend the testing infrastructure to allow for preparation of 3.9 GHz Cavities • 1. BCP treatment • 2. High-Pressure Rinse • 3, Cryostat Insert • 4. RF Equipment / Amplifier • 5. Four Cavities for Qualification of Facility • 6. Replace 1st iteration module • 7. Higher Gradient • 8. Larger Fill Factor (XFEL Prototype) • 9. New HOM Coupler Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

18. 7. "LOLA" at 3 GHz-bunch length and longitudinal phase-space measurements Motivation Most powerful diagnostics for the longitudinal phase space At present a 2.856 GHz structure donated by SLAC is used (fill time ~700 ns) What should be done in the frame of work package Design changes we have in mind Change frequency to 3.0 GHz (a harmonic of the M.O. and bunch frequency) Reduce fill time to below 400 ns (to accommodate 5 MHz bunch repetition rate) Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz

19. 8. HOM beam monitors Motivation HOM can be used as beam position monitors and linac alignment monitors, Very useful for all sc linear accelerators (FLASH, European XFEL, 4GLS…) Following Diagnostics can be done with HOMs: beam position cavity position and tilt in cryomodule feedback phase measurement • What should be done in the frame of work package • diagnostics • measurement of the axis for various modes, in various cavities; • study of cell misalignment, • cavity deformation • measurement of polarization axis for various modes, in various cavities • other possible studies: coupler kicks, steering effect Plans for FP7 at DESY, October 30th, 2006 CERN Jacek Sekutowicz