1 NGLS cryomodule concept John Corlett LBNL for the NGLS linac design-study team TTC 1 st Topical Meeting on CW-SRF Cornell University June 12–14, 2013

2 Beam spreader X-ray beamlines and endstations High stability CW superconducting LINAC High-brightness, high rep-rate injector Expandable to increase capacity and capability NGLS concept Array of independent FELs High repetition rate soft X-ray laser array o Up to 10 6 pulses per second o Average coherent power up to ~100 W Spatially and temporally coherent X-rays (seeded) o Ultrashort pulses from ~1 fs to ~300 fs o Narrow energy bandwidth to 50 meV Tunable X-rays o Adjustable photon energy from 50 – 720 eV, 2 keV in harmonics o Moderate to high flux with – photons/pulse Expandable o Capability (e.g. higher energy, repetition rate, pulse duration, tuning range) o Capacity (multiple FEL beamlines)

3 Multi-Lab collaboration for linac design Minimize cost and development time by maximizing use of existing designs, tooling, infrastructure, and industrialization Pursue design developments for reduced costs and improved performance, leading to reliable and cost-effective CW SCRF electron linac technology that could be realized within 3–5 years Linac approach TESLA/ILC technology Modifications from the ILC design Discrete cryomodules Operating in CW mode

4 Evolution to a compact NGLS ParameterCD0“Optimization”Compact Bunch charge (pC)≤ Repetition rate (MHz)111 Cavity gradient (MV/m) # cryomodules18 – # cavities Beam energy (GeV) Bunch current (mA)≤10.3 RF power (AC) (MW) Cryogenic power (AC) (MW)

5 Q 0 =2x10 10 Nominal operating gradients 16–19 MV/m (~6% installed redundancy) RF power Cryoplant Cryomodules & enclosure Total cost, construction + 15 yrs operations Total cost, construction only Cryomodules & enclosure Cryoplant RF power Cavity accelerating gradient optimization

6 Nominal linac requirements 300 pC 1 MHz 500 A (peak) ≥ 300 fs 1.2 GeV <19 MV/m 10 cryomodules 80 cavities L0L1HLL2L3 CryomoduleCM1CM2-3HL1,2CM4-6CM7-10 E acc (MV/m)-17.2~ V RF per section (MV)  RF (deg) V RF cos  RF per section (MeV) Beam energy at section exit (MeV)

7 RF parameterValueUnit RF frequency1300MHz Operating temperature1.8K Accelerating gradient19MV/m Average Q 0 per CM2x10 10 Cavity length1.038m R/Q1036Ohms Coarse tuner range600kHz Fine tuner range2kHz Lorentz detuning1.5Hz/(MV/m) 2 Cavity alignment requirement0.5mm (rms) Peak detune allowance15Hz Required amplitude stability per cavity0.01% Required phase stability per cavity0.01Deg Q ext 3x10 7 RF beam power per cavity5.5kW RF power needed per cavity8kW Dynamic load per cavity18.4W Installed RF power per cavity9kW Installed RF AC power1.6MW

8 Cryomodule heat loads CryomoduleL0L1L2L3 E, [MV/m] QoQo 2.0E+10 Number of cryomodules1234 Fraction of cavities powered Beam phase angle (deg) various Beam energy at exit (MeV) Dynamic RF load per cavity (W) StaticDynamicStaticDynamicStaticDynamicStaticDynamic Temperature Level1.8 K Static, dynamic sum CM 1.8 K Sum [W] K Static, dynamic sum CM 5K Sum [W] K Static, dynamic sum CM 40K Sum [W] Up to K per cryomodule Design 1.8 K mass flow 118 g/s Installed AC power for cryosystem 2.4 MW

9 Cryomodule concept 8 “ILC” cavities per module Discrete cryomodules each with cold/warm end transitions Distribute 5 K liquid, cool to 1.8 K at cryomodule Magnets, diagnostics & HOM absorbers in warm sections

10 Cryomodule cooling concept (shown for 7 cavities)

11 TESLA CM for reference 300 mm pipe not required for helium flow in single-cryomodule configuration Support “backbone” Large 2-phase pipe and buffer volume to damp pressure fluctuations

12 Tunnel configuration

13 Beam spreader from linac FEL 1 FEL2 FEL3 not to scale R GUN /2 RF Dipole 3 MeV / 1.15mrad R GUN R GUN /4 RF deflecting cavity distributes bunches to FEL beamlines 3.7 mrad deflection Single cavity? E surface H surface R. G. Olave J. R. Delayen

GHz linearizer module  FNAL cryomodule operational at DESY/FLASH and meets requirements  Modify for CW operation >15 MV/m demonstrated >5 MV per cavity 4 cavities per CM NGLS needs 6-7 cavities

15 Minimize/optimize dynamic heat loads | cryogenics plant & distribution Maximize Q 0 Cavity processing | maintenance of Q | magnetic shielding Minimize RF power Cavity / string vibration, pressure stability Reliability (>95% uptime for light sources) Trip rate at 16–19 MV/m? Diagnostics and instrumentation He bath & heat flow from cavity | coax/WG power coupler | He buffer | HOM damping | cavity alignment... Component and cryomodule tests Dressed cavity tests? CM test vendor –> pre-installation? / installed? Integrated cryomodule design considerations

16 Arnaud Allezy, Diego Arbelaez, John Byrd, John Corlett, Charlotte Daniels, Stefano De Santis, William Delp, Peter Denes, Rick Donahue, Lawrence Doolittle, Paul Emma, Daniele Filippetto, James Floyd, Joseph Harkins, Gang Huang, Jin-Young Jung, Derun Li, Tak Pui Lou, Tianhuan Luo, Gabriel Marcus, Marco Monroy, Hiroshi Nishimura, Howard Padmore, Christos Papadopoulos, Chris Pappas, Stefan Paret, Gregory Penn, Massimo Placidi, Soren Prestemon, Donald Prosnitz, Houjun Qian, Ji Qiang, Alessandro Ratti, Matthias Reinsch, David Robin, Fernando Sannibale, Robert Schoenlein, Carlos Serrano, John William Staples, Christoph Steier, Changchun Sun, Marco Venturini, Will Waldron, Weishi Wan, Tony Warwick, Russell Wells, Russell Wilcox, Sergio Zimmermann, Max Zolotorev Camille Ginsburg, Robert Kephart, Arkadiy Klebaner, Thomas Peterson, Alexander Sukhanov Dana Arenius, George Neil, Tom Powers, Joe Preble Chris Adolphsen, Karl Bane, Yuantao Ding, Zhirong Huang, Chris Nantista, Cho-Kuen Ng, Heinz-Dieter Nuhn, Claudio Rivetta, Gennady Stupakov NGLS R&D and design collaboration

17 Backup slides

18 Coupler, tuners, HOM damping Fixed power coupler <10 kW average power TTF-III coupler is complex and expensive Tuners Slow mechanical –600 kHz range Fast piezo-driven –2 kHz range Wakefields HOM damping requirement for 0.3 pC? TESLA HOM couplers with improved cooling XFEL HOM absorber in warm beampipes between cryomodules –Reliability is paramount

19 Heat flow diagram for TESLA-style cavity from CW OPERATION OF SUPERCONDUCTING TESLA CAVITIES, W. Anders, J. Knobloch, O. Kugeler, A. Neumann, BESSY, Berlin, Germany