Design Verification Components Nikolay Solyak LCLSII 3 9

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Design Verification (Components) Nikolay Solyak LCLS-II 3. 9 GHz CM Delta Final Design Review

Design Verification (Components) Nikolay Solyak LCLS-II 3. 9 GHz CM Delta Final Design Review January 29 -30, 2019

Outline • Coupler - Design and specs, - Qext measurement, - HTS test -

Outline • Coupler - Design and specs, - Qext measurement, - HTS test - Thermal properties, heat removal, heat load • HOM coupler • Frequency Tuner - Design and tuning experience • Other components • Summary N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 2

Requirements for LCLS-II 3. 9 GHz coupler. FRD: LCLSII-4. 1_FR-0096 -R 1; PRD: LCLSII-4.

Requirements for LCLS-II 3. 9 GHz coupler. FRD: LCLSII-4. 1_FR-0096 -R 1; PRD: LCLSII-4. 1 -PR-0097 -R 2 https: //docs. slac. stanford. edu/sites/pub/Public ations/SCRF_3. 9_GHz_Cryomodule. pdf Parameter Nominal Min Max Units RF frequency 3900 MHz 64. 7 (2 cav-reserve) 72 MV 14. 9 -180 3. 0× 107 1. 48 1. 9 MV/m degrees Hz k. W Total 3. 9 GHz voltage Average operating gradient Beam to RF Phase Peak detune (with piezo tuner control) Qext (fixed) RF beam power/cavity @ 300 µA RF power/cavity (with overhead) 13. 4 (2 cav in reserve) -150 -90 30 2. 7× 107 2. 4× 107 1. 20 0. 94 *Available power (per Chris A): 0. 9 k. W -10% (overhead)-19%(losses) = 0. 64 k. W N. Solyak / 3. 9 GHz Coupler design FAC review, March, 2018 3

Forward power and max. power in coupler for 0. 3 m. A Eacc=14. 9

Forward power and max. power in coupler for 0. 3 m. A Eacc=14. 9 MV/m, Beam current = 300µA; microphonics = ± 30 Hz • Required Power < 600 W if Beam-to-RF phase in range: [-120°… -200°]* o Cavity is tuned off-resonance (<40 Hz) to minimize forward power • Power dissipation in coupler are below limit (set by 1. 9 k. W total power) *(C. Adolphsen, P. Emma) N. Solyak / 3. 9 GHz Coupler design 4

3. 9 GHz power coupler for LCLS-II CW operation • Fix coupling; Q=2. 7

3. 9 GHz power coupler for LCLS-II CW operation • Fix coupling; Q=2. 7 e 7 (2. 4 e 7 -3. e 7) • Cylindrical cold window (as 1. 3 GHz) • Waveguide warm window • XFEL/FNAL coupler for pulse operation (Pmax = 45 k. W, DF=1. 3%: Pavrg < 0. 6 k. W). • LCLS-II: Pmax = 1. 8 k. W cw in quasi – TW regime: SS Inner Conductor + bellows plating T max Losses K 80 K 4 K 30 microns plating ~1000 9. 2 0. 8 100 microns plating 507 9. 3 0. 8 150 microns plating 427 9. 4 0. 8 N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 o Tmax ~1000 K w/o modification (warm part inner conductor Cu plating 30 um) 5

LCLS-II Main Coupler Design (modification from XFEL design) 1. Cold part (upper picture) §

LCLS-II Main Coupler Design (modification from XFEL design) 1. Cold part (upper picture) § Dimensions of ceramic window § Length of antenna (QL=2. 7 e 7 vs. 1. 5 e 7) § Material of antenna - copper (vs. SS) => Reduce antenna heating and Qext variation (HTS result) Cold part 2. Warm outer part No changes Warm part (outer conductor) 3. Inner conductor of warm section § Cu plating increased from 30 to 150 um. § Reduce number convolution in inner conductor bellows from 20 to 15 Warm part (inner conductor) and WG box § 3 existing warm sections rebuilt to prototype: Tested at RT, power tests, HTS with warm window N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 6

Qext variation control CMM measurements on 4 pre-production cavities A Drawing A=69. 75+/-0. 2

Qext variation control CMM measurements on 4 pre-production cavities A Drawing A=69. 75+/-0. 2 mm CMM meas. difference 3 HRI 01=70. 128 (+0. 378 mm) 3 HRI 04=69. 185 (-0. 565 mm) Note: ~0. 9 mm difference in coupler port position To reduce coupling variation in production cavities: Endgroup # 5 6 17 18 19 20 22 23 24 • RI measures antenna coupling through end-groups. S-parameters should be in specified range, if not coupler flange is trimmed. • 3 length of diamond seals (4. 5; 5; 5. 5) to reduce coupling variation. Presenter | Presentation Title QE 1 2. 76 E+06 2. 77 E+06 2. 45 E+06 2. 79 E+06 2. 82 E+06 2. 59 E+06 2. 22 E+06 2. 41 E+06 2. 83 E+06 2/25/2021 7

Qext variation control: simulations, errors and measurements (prototype cavities and couplers) Qnom Coupler (38

Qext variation control: simulations, errors and measurements (prototype cavities and couplers) Qnom Coupler (38 mm) L, [mm]* 2. 5 E 7 39. 8 - 1. 5 mm Qext measurements with prototype cavities Cavity # Coupler # length mm Qext x 106 1 1 52. 2* 0. 96 2 1 52. 2* 1. 5 1 1 43 12. 5 1 2 52. 3* 0. 91 2 2 43. 1 16. 5 4 2 43. 1 15. 4 N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 Sensitivity of QL to errors: • Field flatness (90%) QL=20% • Antenna length: 27. 5% per mm ~ 0. 1 1 mm <1 mm • Antenna offset: ~ 5% per 1 mm • Coupler-to-cav distance ~10% per mm <1 mm • Other (beampipe elipticity, etc - ? ) • QL variation mostly come from cavity errors • XFEL experience: QL=(4. 1 -8. 3)· 106 in CM 8

Qext measurement on the first production bare cavity. 3 HRI 08 production cavity with

Qext measurement on the first production bare cavity. 3 HRI 08 production cavity with prototype coupler Linear-fit approximation Mode #9 AMAX Quadratic-fit approximation Qext based on S 11 measurements Freq, MHz Qext , 107 linear 5700 2. 12 quadratic 1. 92 1. 89 Q 09 ≈ 5700 @RT *Antenna L=43. 1 mm=> for 42 mm (production) expected Qext~(2. 6 -3)*107; 3891. 85 Slope subtracted Q 0 Will be re-checked on 2 dressed production cavities (5 & 8) with production coupler and corrected if needed N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 9

3. 9 GHz cavity: Horizontal testing • Conditions similar to cryomodule operation • Integrated

3. 9 GHz cavity: Horizontal testing • Conditions similar to cryomodule operation • Integrated testing of all components - Including: Magnetic shielding, power coupler, tuner, HOM couplers • Resolve possible interference N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 10

HTS 3. 9 GHz system Integration test. 3. 9 GHz coupler thermometry HTTP 6

HTS 3. 9 GHz system Integration test. 3. 9 GHz coupler thermometry HTTP 6 HTTX 30 HTTX 29 HTTXM 4 Hardware: Cavity - 3 HRI 03 Coupler #2, antenna trimmed to 43. 1 mm QL (RT) = 1. 54 e+7 QL(2 K /static) = 1. 70 e+7 QL(2 K/dynam)= 1. 05 e+7 1 k. W SW Coupling depends on RF power (due to antenna heating). Copper antenna (vs. SS) will fix that problem N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 11

Thermal simulations: Effect of antenna material, Copper vs. SS Antenna: SS+50 μm Cu covered

Thermal simulations: Effect of antenna material, Copper vs. SS Antenna: SS+50 μm Cu covered / Solid copper Parameters: P in= 1 k. W SW ON-resonance: 10μm outer plating, ε=9. 8, tan=3 e-4, roughness 10: warm inner: 120 μm Cu coating of SS inner conductor, 15 bellow conv. 10 K HTS: 150 K (CM: 110 K) TIR ~ 411/430 K Tmax ~ 469/475 K short 320 K Port: 1 k. W Tant = 481/183 K Temperature distribution along inner conductor vs. Z N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019

Coupler assembled at Cavity and Tested at HTS 0. 8 k. W SW, OFF-resonance

Coupler assembled at Cavity and Tested at HTS 0. 8 k. W SW, OFF-resonance 0. 8 k. W, SW, ON-resonance TCT 100~167 K CT flange~160 K PRF=0. 8 k. W IR~390 K ΔTbraid TIR~385 K T 80 K_shield Expected maximum • <130 K at 50 K flange – (from 170 K at HT) Temperatures in CM: • <400 K at inner conductor bellows (from <420 K at HTS) Note: HTS uses LN 2 line (90 K) vs. CM He line (40 K), all T related to this line will be by ~40 K lower in CM N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 13

Thermal simulation summary Temp. boundaries: 10/150/320 K; RF power = 1 k. W, SW.

Thermal simulation summary Temp. boundaries: 10/150/320 K; RF power = 1 k. W, SW. Antenna material T max, K Tprobe Tmax, K coupler K antenna Pflux, W @ 4 K Pflux, W @ 80 K Static Solid Cu Onresonance Offresonance Static SS + 50 m ONresonance Cu plated Offresonance ΔL, μm cold-warm dyn-static ΔQ/QL % -57 475 430 183 0. 87 13. 4 22 0. 6 428 411 174 0. 75 9. 8 15 0. 4 0. 57 1. 43 -123 469 411 481 1. 05 15. 3 873 25* 447 422 386 0. 9 11. 2 591 16 w/o thermal radiation *Confirm at HTS test Copper antenna reduce temperature at tip and provides smaller Qext deviation in dynamic regime to compare with SS antenna N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 14

Temperature and power dissipation at 5 K flange Braid temp gradient 5 K –

Temperature and power dissipation at 5 K flange Braid temp gradient 5 K – end. ΔT=HTTX 30 -HTTX 29 OFF-resonance ON-resonance Pstatic = 0. 7 W; Pdyn (on/off) = 1. 9/1. 6 W; Temperature, K Forward power (W) 80 K – end. Cryo heat load Infra-red sensor Temperature (inner conductor, warm part) N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 ~ 12 W 392 K Measured Power flux ~14 W Pdyn (on/off) = 14/12 W; > 387 K Note: expected Tmax (inner conductor bellow) ~20 K above IR meas. (simul). 15

Thermal intercept design in 3. 9 GHz CM Coupler uses same straps as in

Thermal intercept design in 3. 9 GHz CM Coupler uses same straps as in 1. 3 GHz cryomodule • power flux less than in 1. 3 GHz coupler • same straps are used as for 1. 3 GHz system (L~150 mm, S=120 mm 2; 0. 29 W/K) N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 16

Main Coupler Summary • Three coupler prototypes (warm part) were built and tested: o

Main Coupler Summary • Three coupler prototypes (warm part) were built and tested: o QC inspection and RF measurements o 2 couplers were HP processed at warm test stand at 2 k. W cw. o 1 assembled on dressed cavity and tested in HTS at 1 k. W SW (integrated system test). o Qext measurements with coupler installed on prototype cavity (1, 2, 4) and one production cavity (3 HRI 08) at room temperature. • It was found that major contribution to Qext variation is coming from cavity dimension errors. To minimize variation the RF coupling measurements of coupler end-group were included as part of cavity production process • Thermal design verified in HTS test and incorporated in CM design. • Coupler procurement in progress (8 couplers are received) • First production coupler will be assembled on production cavity (5 &8) to verify Qext N. Solyak - LCS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 17

HOM coupler design LCLS-II modified XFEL (INFN/FNAL) design to reduce risks of tuning and

HOM coupler design LCLS-II modified XFEL (INFN/FNAL) design to reduce risks of tuning and heating problems in CW operation. o Reduce beam pipe and bellow diameter from 40 to 38 mm to move trapped parasitic mode away to improve the tuning of HOM notch frequency. o. Modification of HOM coupler to reduce heating • In XFEL design lowest mode are closer to operation node (min ~10 -20 MHz vs. 100 MHz in simul. ) üF-part modification less penetration of • beam pipe aperture 38 mm allows to antenna inside HOM to reduce heating detune the HOM by ~ 100 MHz up. üIncrease wall thickness of HOM hat to 1. 3 mm to prevent cracks and vacuum leak üShorter length of HOM feedthrough antenna (Fermilab vs. XFEL) N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 18

HOM F-part modification to reduce antenna heating Reduce penetration to beam pipe. Increase length

HOM F-part modification to reduce antenna heating Reduce penetration to beam pipe. Increase length of bump in F-part XFEL/FLASH G = 3. 2 e 8 LCLS-II design G = 1. 74 e 9 A. Lunin/khabiboulline • Current design HOM antenna quenches at ~20 MV/m in VTS. Expected that quench limit will even lower in CW regime at HTS and CM. • RF power dissipation on HOM antenna reduced by factor of 5. 4 after modification N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 19

LCLS-II 3. 9 GHz cavity HOM coupler notch frequency tuning Thickness of hat was

LCLS-II 3. 9 GHz cavity HOM coupler notch frequency tuning Thickness of hat was a concern • LCLS-II increases to 1. 3 mm • Past experience: q FLASH: 1 mm => broken and vacuum leaks q XFEL: 1. 15 mm =>one prototype cavity has leak. Tuning fixture HOMc to PU MC to HOMpu MC to PU No damage, no tuning problem with HOM tuning at 6 cavities S 21 measurements before S 21 measurements after tuning of HOM coupler notch frequencies. 35 -40 frequencies d. B lower signal at operating mode N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 Courtesy of T. Khabiboulline 20

LCLS-II 3. 9 GHz Frequency Blade Tuner • Modified INFN slim blade tuner design

LCLS-II 3. 9 GHz Frequency Blade Tuner • Modified INFN slim blade tuner design • Added 2 piezo-capsules for fast tuning • Active elements same as used for 1. 3 GHz LCLS-II tuner Tuner Specifications INFN (Eu. XFEL) tuner Other tuner related parameters Dressed 3. 9 GHz cavity with tuner assembled for test at HTS N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 Courtesy of Yuriy Pischalnikov 21

Cold Tuner Tests: (Slow/Coarse Tuner test results) Detuning the cavity with stepper motor Slow

Cold Tuner Tests: (Slow/Coarse Tuner test results) Detuning the cavity with stepper motor Slow tuner performances: ü Range more than 700 k. Hz ü Resolution 12 Hz/step ü Hysteresis ~500 Hz Tuner operational region Cavity stretched by tuner (both piezo loaded) Cavity compressed through safety rods (non-operational region) Region where cavity o During assembly tuner on the cavity non-constrained by safety gaps were set to 300 um. tuner (cold) o After cool-down gap decreased to 100 um & both piezo were operational/ no locking by safety rods. N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 Safety gaps 300 um (warm) 22

Cold Tuner Tests: (Fast/Fine Tuner test results) § The piezo detuning measurement was done

Cold Tuner Tests: (Fast/Fine Tuner test results) § The piezo detuning measurement was done after the cavity was stretched 240 k. Hz from the end of section B § The sensitivity for both piezo is 120 Hz/V and at 100 V a detuning of 13 k. Hz was observed (for just ½ of one piezo-stack detuning will be ~3 k. Hz (with 1 k. Hz specs) 120 Hz/V Detuning the cavity with fast/piezo tuner in region C. N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 23

Tuner Summary • Design Verification Test of the cold dressed cavity/tuner system confirmed that

Tuner Summary • Design Verification Test of the cold dressed cavity/tuner system confirmed that tuner performances met or exceed specifications • Developed (and confirmed with tests) procedure of the tuner assembly on the dressed cavity (including setting safety gaps) • Dressed Cavity/Magnetic shielding/Tuner integration efforts lead to small modifications that incorporated into production drawings for tuners and magnetic shielding N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 24

BPM and HOM absorber same as for 1. 3 GHz CM Concept: Use 1.

BPM and HOM absorber same as for 1. 3 GHz CM Concept: Use 1. 3 GHz beam line components (ID=78 mm) in transition between cavity string: • BPM, • Gate-valve, • Spool pieces, • Beamline HOM absorber Optimize length and shape of transition from ø 38 mm (cavity) to ø 78 mm for minimum wakefields. • Short ~25 mm in flange (XFEL) • Long >300 mm in spool-piece (upstream end) N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 25

Component Design Verification Summary • Prototypes of all critical components (cavity, coupler, frequency tuner,

Component Design Verification Summary • Prototypes of all critical components (cavity, coupler, frequency tuner, thermal intercepts) of the 3. 9 GHz system were built and tested at room temperature and at cold environment (HTS) in integrated system test. • As a result of tests a small modifications incorporated into the production drawings for coupler, tuners and magnetic shielding to meet requirements. • Developed (and confirmed with tests) procedure of the tuning and assembly of the components and QC inspection of the production components (J. Blower) N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 26

Acknowledgements Many thanks to everyone who contributed to this talk, special thanks to T.

Acknowledgements Many thanks to everyone who contributed to this talk, special thanks to T. Khabiboulline, I. Gonin, A. Lunin, S. Kazakov, R. Stanek, C. Ginzburg, E. Harms, C. Grimm, M. Foley, Y. Pischalnikov, T. Arkan, A. Grassellino, G. Wu, O. Prokofiev, J. Ozelis, A. Saini, J. Kaluzny, S. Yakovlev, H. Awida, T. Peterson, Y. Orlov, Y. He, E. Borissov, … N. Solyak - LCLS-II 3. 9 GHz CM Delta FDR, Jan. 29 -30 2019 27