Superconducting linac design associated MEBT JeanLuc BIARROTTE CNRSIN

Superconducting linac design & associated MEBT Jean-Luc BIARROTTE CNRS-IN 2 P 3 / IPN Orsay, France J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 1

1. MYRRHA lattice design 2. Longitudinal optimisation 3. Transverse beam dynamics 4. The MEBT beam line 5. Conclusion J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 2

MYRRHA superconducting cavities Ø 704. 4 MHz elliptical cavities (CEA/CNRS/INFN) Eacc given at βOPT Epk/Eacc Bpk/Eacc 5 -cells βg=0. 47 0. 51 3. 34 5. 50 m. T/MV/m 5 -cells βg=0. 66 0. 70 2. 49 4. 65 m. T/MV/m Ø 352. 2 MHz spoke cavities (CNRS) Eacc given at βOPT Epk/Eacc 1 -spoke βg=0. 35 0. 37 4. 7 2 nd generation 0. 37 1 -spoke βg=0. 35 V 0 4. 4 2 nd generation ESS 0. 50 2 -spoke βg=0. 5 V 0 4. 5 Bpk/Eacc Wall-towall 12. 8 ≈36 cm 8. 3 ≈42 cm 7. 0 ≈78 cm m. T/MV/m Keep in mind that very few spoke test results exist J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 3

MYRRHA superconducting cavities Ø Choice of operation point → analysis of SNS medium-beta SC cavities o βg 0. 61 average operation: Eacc_MEAN = 12. 5 MV/m o corresponding to Bpk=72 m. T, Epk= 34 MV/m → add 25% margins for MYRRHA fault-tolerance o Nominal operation limited by Epk= 27. 5 MV/m → Eacc_nom = 11. 0 MV/m (@βOPT) for βg 0. 65 cavities → Eacc_nom = 8. 2 MV/m (@βOPT) for βg 0. 47 cavities → Eacc_nom = 6. 2 MV/m (@βOPT) for spoke cavities J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 4

MYRRHA cryomodules Ø Strategy = short modules (<6 m) w/ RT quad. doublets → need for modularity, fast maintenance, beam diagnostics at regular locations 42 54 56 Nβgλ/2 Ø Elliptical 2 K cryomodule → SNS as a basis Wall-to-wall Ø Spoke 2 K cryomodule 42 23 52 → MAX preliminary designs as a basis J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 5

MYRRHA warm sections Ø Inter-module → SPIRAL-2 as a basis → + margins ØQuads → Sufficiently long (Lmag > 4 Rap) to minimize fringe field effects → Low gradients to ensure Bpole< 0. 3 T, minimize NI ( α B’Rap 2 ) and ensure reliable operation → 3 quadrupole families o section #1: Lmag= 20 cm, 60 ( 56 for cav. ) to ensure B’ < 10 T/m (& even less) o section #2: Lmag= 30 cm, 85 ( 80 for cav. ) to ensure B’ < 7 T/m o section #3: Lmag= 40 cm, 95 ( 90 for cav. ) to ensure B’ < 6. 3 T/m J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 6

1. MYRRHA lattice design 2. Longitudinal optimisation 3. Transverse beam dynamics 4. The MEBT beam line 5. Conclusion J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 7

Longitudinal beam dynamics Ø 1. Keep phase advance at zero-current σL 0 < 90° / lattice → GOAL = avoid SC-driven parametric resonances & instabilities in mismatched conditions → Implies limitations on Eacc (and L) Ø 2. Provide high longitudinal acceptance → GOAL = avoid longitudinal beam losses & easily accept fault conditions → Implies low enough synchronous phases (φs= -40° at input, keep φs< -15°) & to keep constant phase acceptance through linac, especially at the frequency jump Ø 3. Continuity of the phase advance per meter (< 2°/m) → GOAL = minimize the potential for mismatch and assure a current independent lattice → Implies especially limitations on Eacc at the frequency jump J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 8

Some LINAC optimisation results (w/ Gen. Lin. Win) Ø Results with 1 -SPOKE 35 + 5 -ELLIPT 47 + 5 -ELLIPT 65 3 cav/mod + 2 cav/mod, + 4 cav/mod (previous EUROTRANS scheme) ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 72 Cav/Cryo: 3/ 24 Cryo/Per: 1/ 24 L: 84. 2400 m ßg: 0. 493 ßtrans: 0. 400 Eo: 86. 526 Me. V Sect: 2 -> Cell/Cav: 5/ 28 Cav/Cryo: 2/ 14 Cryo/Per: 1/ 14 L: 52. 6400 m ßg: 0. 470 ßtrans: 0. 530 Eo: 172. 822 Me. V Sect: 3 -> Cell/Cav: 5/ 64 Cav/Cryo: 4/ 16 Cryo/Per: 1/ 16 L: 107. 5200 m ßg: 0. 658 ßfinal: 0. 795 Eo: 607. 536 Me. V NSection: 3 --> NCav: 164 NCryo: 54 NLattice: 54 Length: 244. 4 m Energy: 607. 536 Me. V ------------------------------------------------------------------------------------------------------- 2 cav/mod + 4 cav/mod ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 48 Cav/Cryo: 2/ 24 Cryo/Per: 1/ 24 L: 68. 6400 m ßg: 0. 493 ßtrans: 0. 390 Eo: 80. 819 Me. V Sect: 2 -> Cell/Cav: 5/ 34 Cav/Cryo: 2/ 17 Cryo/Per: 1/ 17 L: 63. 9200 m ßg: 0. 470 ßtrans: 0. 540 Eo: 183. 868 Me. V Sect: 3 -> Cell/Cav: 5/ 60 Cav/Cryo: 4/ 15 Cryo/Per: 1/ 15 L: 100. 8000 m ßg: 0. 658 ßfinal: 0. 793 Eo: 602. 421 Me. V NSection: 3 --> NCav: 142 NCryo: 56 NLattice: 56 Length: 233. 36 m Energy: 602. 421 Me. V ------------------------------------------------------------------------------------------------------- 2 cav/mod + 3 cav/mod + 4 cav/mod ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 52 Cav/Cryo: 2/ 26 Cryo/Per: 1/ 26 L: 74. 3600 m ßg: 0. 493 ßtrans: 0. 400 Eo: 88. 309 Me. V Sect: 2 -> Cell/Cav: 5/ 36 Cav/Cryo: 3/ 12 Cryo/Per: 1/ 12 L: 56. 8800 m ßg: 0. 470 ßtrans: 0. 540 Eo: 182. 259 Me. V Sect: 3 -> Cell/Cav: 5/ 60 Cav/Cryo: 4/ 15 Cryo/Per: 1/ 15 L: 100. 8000 m ßg: 0. 658 ßfinal: 0. 793 Eo: 600. 356 Me. V NSection: 3 --> NCav: 148 NCryo: 53 NLattice: 53 Length: 232. 04 m Energy: 600. 356 Me. V ------------------------------------------------------------------------------------------------------- J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 9

Some LINAC optimisation results (spoke options) Ø Results with 1 -SPOKE 35 + 2 -SPOKE 50 + 5 -ELLIPT 65 2 cav/mod + 3 cav/mod, + 4 cav/mod ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 36 Cav/Cryo: 2/ 18 Cryo/Per: 1/ 18 L: 51. 4800 m ßg: 0. 493 ßtrans: 0. 330 Eo: 58. 497 Me. V Sect: 2 -> Cell/Cav: 3/ 33 Cav/Cryo: 3/ 11 Cryo/Per: 1/ 11 L: 53. 2400 m ßg: 0. 611 ßtrans: 0. 521 Eo: 168. 334 Me. V Sect: 3 -> Cell/Cav: 5/ 72 Cav/Cryo: 4/ 18 Cryo/Per: 1/ 18 L: 120. 9600 m ßg: 0. 658 ßfinal: 0. 794 Eo: 606. 199 Me. V NSection: 3 --> NCav: 141 NCryo: 47 NLattice: 47 Length: 225. 68 m Energy: 606. 199 Me. V ------------------------------------------------------------------------------------------------------- 2 cav/mod + 4 cav/mod ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 40 Cav/Cryo: 2/ 20 Cryo/Per: 1/ 20 L: 57. 2000 m ßg: 0. 493 ßtrans: 0. 350 Eo: 65. 872 Me. V Sect: 2 -> Cell/Cav: 3/ 40 Cav/Cryo: 4/ 10 Cryo/Per: 1/ 10 L: 58. 5000 m ßg: 0. 611 ßtrans: 0. 556 Eo: 199. 193 Me. V Sect: 3 -> Cell/Cav: 5/ 64 Cav/Cryo: 4/ 16 Cryo/Per: 1/ 16 L: 107. 5200 m ßg: 0. 658 ßfinal: 0. 793 Eo: 602. 607 Me. V NSection: 3 --> NCav: 144 NCryo: 46 NLattice: 46 Length: 223. 22 m Energy: 602. 607 Me. V ------------------------------------------------------------------------------------------------------- Ø Results with 1 -SPOKE 35 + 2 -SPOKE 50 + 3 -SPOKE 65 2 cav/mod + 3 cav/mod + 4 cav/mod ------------------------------------------------------------------------------------------------------Sect: 1 -> Cell/Cav: 2/ 36 Cav/Cryo: 2/ 18 Cryo/Per: 1/ 18 L: 51. 4800 m ßg: 0. 493 ßtrans: 0. 330 Eo: 58. 497 Me. V Sect: 2 -> Cell/Cav: 3/ 36 Cav/Cryo: 3/ 12 Cryo/Per: 1/ 12 L: 58. 0800 m ßg: 0. 611 ßtrans: 0. 533 Eo: 179. 309 Me. V Sect: 3 -> Cell/Cav: 3/ 84 Cav/Cryo: 4/ 21 Cryo/Per: 1/ 21 L: 152. 2500 m ßg: 0. 846 ßfinal: 0. 794 Eo: 604. 977 Me. V NSection: 3 --> NCav: 156 NCryo: 51 NLattice: 51 Length: 261. 81 m Energy: 604. 977 Me. V ------------------------------------------------------------------------------------------------------J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 10

Conclusions on longitudinal design 1 -SPOKE 35 2 cav/module Section # Einput (Me. V) Eoutput (Me. V) Cav. technology Cav. freq. (MHz) Cavity geom. β Nb of cells / cav. Focusing type Nb cav / cryom. Total nb of cav. Nominal Eacc (MV/m) Synch. phase (deg) Beam load / cav (k. W) Section length (m) 5 -ELLIPT 47 2 cav/module 2 -SPOKE 50 (ESS) is also a viable back-up candidate #1 #2 17. 0 80. 8 80. 9 183. 9 Spoke Elliptical 352. 2 704. 4 0. 35 0. 47 2 5 NC quadrupole doublets 2 2 48 34 6. 2 8. 2 -40 to -19 -38 to -15 1. 5 to 7. 5 2. 5 to 17 68. 6 63. 9 5 -ELLIPT 65 4 cav/module #3 183. 9 600. 0 εacc/ εRMS ≈ 70 0. 65 5 4 60 11. 0 14 to 32 100. 8 Ø Overall linac: 233 metres & 142 cavities Longitudinal acceptance of main linac & 17 Me. V input beam @176 MHz → 3 sections is a clear choice for a 17 -600 Me. V SC linac → Playing around with cavity beta & nb cells does’nt change much the picture J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 11

MYRRHA linac longitudinal tunings J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 12

Longitudinal acceptance Ø New MAX design (176 MHz) 70 εacc/ εRMS ≈ J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Ø Old EUROTRANS design (352 MHz) εacc/ εRMS ≈ 87. 5 13

1. MYRRHA lattice design 2. Longitudinal optimisation 3. Transverse beam dynamics 4. The MEBT beam line 5. Conclusion J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 14

Rules for transverse beam dynamics Ø 1. Keep phase advance at zero-current σT 0 < 90° / lattice Ex 1: σT 0 = 95° I = 4 m. A Ex 2: σL 0 = 95° I = 4 m. A J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 15

Rules for transverse beam dynamics Ø 2. Keep σT > 70%σL to stay away from the dangerous parametric resonance σT = σL/2 Ex: σT 0 = 45° I = 0 m. A Ø 3. Avoid emittance exchange between T & L planes via SC-driven resonances Ex: σT 0 ~ σL 0 I = 4 m. A MYRRHA equipartionned region J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 16

Rules for transverse beam dynamics Ø 4. Provide clean matching between sections in all planes to minimize emittance growth (+ again, continuity of the phase advance per meter to minimize sensitivity to mismatch) Ex: Matched beam, but no matching btwn sections J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 17

Choices for MYRRHA transverse tuning Ø OPTION 1: “Strong” focusing Ø OPTION 2: “Weak” focusing → Optimal transverse acceptance → No σT=σL crossing → Close to equipartitioning → Reduced quad gradients J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 18

Beam envelopes & quad gradients Ø OPTION 1: “Strong” focusing Ø OPTION 2: “Weak” focusing Gmax = 6. 6 T/m Gmax = 7. 4 T/m J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 5. 5 T/m Gmax = 5. 8 T/m Gmax = 6. 1 T/m Gmax = 4. 8 T/m 19

Emittance growth (4σ gaussian beam) Ø OPTION 1: “Strong” focusing -1% +3% J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Ø OPTION 2: “Weak” focusing 0% +2% 20

Emittance growth (“real” beam from injector simulation) Ø OPTION 1: “Strong” focusing Ø OPTION 2: “Weak” focusing -1% +1% +3% J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 21

Transverse acceptance Ø OPTION 1: “Strong” focusing /< /< RMS>= 30. 3 33. 7 17. 2 J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Ø OPTION 2: “Weak” focusing /< /< RMS>= 24. 7 27. 6 14. 6 22

Tolerance to 30% mismatch +++ Ø OPTION 1: “Strong” focusing +25% +3% J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Ø OPTION 2: “Weak” focusing +16% +9% 23

Tolerance to 30% mismatch +-+ Ø OPTION 1: “Strong” focusing +11% +20% J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Ø OPTION 2: “Weak” focusing +7% +24% 24

Sensitivity to current change Ø OPTION 1: “Strong” focusing I = 0 m. A I = 6 m. A I = 0 m. A -1% -3% +1% Ø OPTION 2: “Weak” focusing +4% J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 I = 6 m. A -2% -3% +1% +4% 25

Summary on SC linac design Ø MYRRHA longitudinal design → 233 metres long & 142 cavities (1 -SPOKE 35, 5 -ELLIPT 47, 5 -ELLIPT 65) → ESS-type spoke cav. could be a back-up solution for fam #2 – R&D to be followed → Modular scheme & warm focusing Ø Beam dynamics is very robust → Low sensitivity to mismatch and to beam current change → High acceptance even with the new 176 MHz input beam → Valid for both « weak » and « strong » transverse focusing schemes Ø NEXT STEPS. . . → Connect the consolidated 17 Me. V injector → Include full 3 D field-maps (if necessary) → Monte-Carlo error studies in nominal and fault operations → Look again at HOM analysis & BBU simulations (just to check) J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 26

1. MYRRHA lattice design 2. Longitudinal optimisation 3. Transverse beam dynamics 4. The MEBT beam line 5. Conclusion J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 27

17 Me. V MEBT preliminary design 12 m INJECTOR-1 MAIN LINAC 7 m INJECTOR-2 → 2 dipoles 45° (ρ=0. 75 m, gap 50 mm, 22. 5° edges) & 1 switching 45° magnet → 15 or 18 quadrupoles (same as spoke linac) → 4 re-bunchers (up to 0. 5 MV voltage, probably SC spoke cavities) → Diagnostics (BPMs, WS, To. Fs) & collimators / halo monitors (tb optimised with error studies) + two straight beam dump lines for tuning (+ if necessary 2 fast kickers for pulse cleaning) J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 28

17 Me. V MEBT 99% beam envelopes MAIN LINAC J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 29

MEBT 17 – 600 Me. V STE simulation Main LINAC J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 Line to reactor 30

17 – 600 Me. V STE simulation 17 Me. V input beam from LORASR J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 600 Me. V beam on target 31

1. MYRRHA lattice design 2. Longitudinal optimisation 3. Transverse beam dynamics 4. The MEBT beam line 5. Conclusion J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 32

Conclusion Ø The layout of the 17 -600 Me. V superconducting linac is consolidated (233 metres long & 142 cavities) Ø Beam dynamics studies show good behaviour and low sensitivity to mismatches & current variations Ø Next main steps in 2013 are: üachieve the injector consolidation & connect it to the main linac, üdefine the detailed tuning strategy from the source to target üperform extensive STE error studies üValidate/optimise the full linac design by the end of MAX (Feb. 2014) J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 33

Thank you! http: //ipnweb. in 2 p 3. fr/MAX/ http: //myrrha. sckcen. be/ J-Luc Biarrotte, 1 st Myrrha design review, Brussels, November 12 th, 2012 34