Update on Lattices and Beam Dynamics Studies Alex

Update on Lattices and Beam Dynamics Studies Alex Bogacz for the JLab's Study Group on PERLE* *A. Bogacz, D. Douglas, A. Hutton, F. Marhauser, C. Tennant, R. Rimmer, Y. Roblin Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 1

Outline What will PERLE Test? PERLE design PERLE@Orsay (400 Me. V) - Layout Multi-pass linac Optics in ER mode Arc Optics Architecture Switchyard Challenges, Moving towards TDR Initial CSR/Microbunching Instability Studies Summary and Outlook Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 2

What will PERLE Test? PERLE originated as the LHe. C Test Facility is a sub-Ge. V-scale accelerator system invoking a unique combination of parameters, technology, and design choices Very high “virtual” beam power (~10 MW) Moderately high current and bunch charge (15 m. Amp, 375 p. C) Conventional accelerator transport system design Common beam transport for acceleration and recovery Extremely large dynamic range (ratio of full to final energy 80: 1) Multiple passes (3) PERLE offers unique opportunity to controllably study of virtually every effect of interest in the next generation of ERL design Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 3

PERLE – CDR Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 4

PERLE Downsizing CDR (900 Me. V) Alessandra Valloni Alex Bogacz 14 m 45 m ‘PERLE@Orsay’(400 Me. V) 5. 5 24 m m Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 5

PERLE@Orsay - Layout 400 Me. V 1: 3: 5 DE = 65. 5 Me. V injector 5. 5 5 Me. V 24 m 0. 8 m m DE = 65. 5 Me. V 2: 4: 6 5 Me. V p dum DC = l. RF/2 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 6

PERLE@Orsay - Layout 400 Me. V 1: 3: 5 DE = 65. 5 Me. V injector 5. 5 5 Me. V 24 m 0. 8 m m DE = 65. 5 Me. V 2: 4: 6 5 Me. V p dum DC = l. RF/2 Three passes ‘up’ + Three passes ‘down’ Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 7

PERLE@Orsay - Baseline Parameters 5 400 (375 p. C) (20 th sub-harmonic) Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 8

PERLE@Orsay - Layout Top view 5. 5 m 24 m 4 m 2: 4: 6 10 m Side view 1: 3: 5 0. 4 m + 0. 4 m Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 9

PERLE Magnet Design (dipoles and quads) Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 10

Linac, Cryo-module - Layout SNS-like cryomodule 801. 58 MHz RF, 5 -cell cavity: l = 37. 40 cm Lc = 5 l/2 = 93. 50 cm 1 m 8. 49 Grad = 17. 5 Me. V/m (16. 4 Me. V per cavity) 10 DE= 65. 5 Me. V per Cryo-module 0 BETA_X&Y[m] Linac length: 26 × l. RF 0 BETA_X Re-injection chicane BETA_Y 9. 72 Cryo-module (8. 491 m) Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 11

JLAB/CERN Collaboration on 802 MHz Cavity - First 802 MHz Niobium single-cell cavity has been completed at JLab, the cavity is now being postprocessed prior to vertical RF testing 2 copper 802 MHz cavities will be produced for R&D purposes and will be sent to CERN Fabrication Complete Oct. 19, 2017 - One bare Niobium five-cell 802 MHz design is being fabricated, completion expected by end of Oct. 2017 Preliminary evaluation of HOM’s has been carried out F. Marhauser Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 12

Multi-pass Linac ER Optics Einj Linac 1 E 1 E 2 Arc 2, 4, 6 E 2 Arc 1, 3, 5 Linac 2 BETA_X&Y[m] 12 Linac 1 0 Acceleration/Deceleration 0 Einj BETA_X BETA_Y DISP_X E 1 DISP_Y E 2 59. 2518 E 3 E 4 E 5 E 6 × 3 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 13

Multi-pass Linac ER Optics Einj Linac 1 E 1 E 2 Arc 2, 4, 6 E 2 Arc 1, 3, 5 E 2 Linac 2 E 1 Einj E 1 BETA_X&Y[m] 12 Linac 2 0 Acceleration/Deceleration 0 E 6 BETA_X BETA_Y DISP_X E 5 DISP_Y E 4 59. 2518 E 3 E 2 E 1 Einj × 3 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 14

BETA_X&Y[m] 12 Multi-pass ER Optics 0 Acceleration 0 BETA_X BETA_Y DISP_X E 2 E 1 59. 2518 E 4 E 3 E 5 E 6 BETA_X&Y[m] 12 Einj DISP_Y 0 Deceleration 0 E 6 BETA_X BETA_Y E 5 DISP_X DISP_Y 59. 2518 E 3 E 4 E 2 E 1 Einj Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 15

10 2 Arc 6 (5, 4) Optics – FMC Lattice 4× 450 bends Qx, y = 1. 25 0 -2 DISP_X&Y[m] BETA_X&Y[m] 399 Me. V 0 BETA_X BETA_Y DISP_X triplet: Q 1 Q 2 Q 3 DISP_Y 7. 70429 singlet: Q 4 triplet: Q 3 Q 2 Q 1 Quadrupoles: Dipoles: (91. 2 cm long) B = 1. 2 Tesla Q 1 Q 2 Q 3 L[cm] =10 L[cm] =15 L[cm] =10 G[T/m] = - 23. 6 G[T/m] = 28. 2 G[T/m] = - 22. 4 Q 4 L[cm] =10 G[T/m] = 8. 6 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy 16

10 2 Arc 3 (2, 1) Optics – FMC Lattice 4× 450 bends Qx, y = 1. 25 0 -2 DISP_X&Y[m] BETA_X&Y[m] 202 Me. V 0 BETA_X BETA_Y DISP_X triplet: Q 1 Q 2 Q 3 DISP_Y 7. 52246 singlet: Q 4 triplet: Q 3 Q 2 Q 1 Quadrupoles: Dipoles: (45. 6 cm long) B = 1. 2 Tesla Q 1 Q 2 Q 3 L[cm] =10 L[cm] =15 L[cm] =10 G[T/m] = - 13. 2 G[T/m] = 13. 1 G[T/m] = - 9. 3 Q 4 L[cm] =10 G[T/m] = 3. 1 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy 17

Vert. Switchyard CEBAF-like Architecture Dipoles: (20 and 40 cm long) B = 0. 8 Tesla Energies 1: 3: 5 T. Michalski Dipoles: (30 cm long) B = 1. 2 Tesla Energies 1: 2: 3 Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 18

Vertical Spreaders - Optics Spr. 1 (71 Me. V) vertical step I DISP_Y 4. 27981 vertical step II 1 DISP_X&Y[m] 20 0 -1 DISP_X BETA_X&Y[m] BETA_Y 0 BETA_X DISP_X&Y[m] 0 -1 0 BETA_X&Y[m] 20 1 Spr. 5 (333 Me. V) BETA_X BETA_Y DISP_X DISP_Y 4. 023 vertical chicane Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 19

20 2 Arc 1 Optics (71 Me. V) DISP_X&Y[m] BETA_X&Y[m] Isochronous Arc 0 -3 pathlength: 42 × l. RF 0 BETA_X BETA_Y DISP_X DISP_Y 15. 71 2 -step vert. Spreader 2 -step vert. Recombiner 1800 Arc Spr. dipoles: Arc dipoles : Rec. dipoles: 4 450 bends L = 20 cm L = 45. 6 cm L = 20 cm B = 9. 5 k. Gauss B = 4. 5 k. Gauss B = 9. 5 k. Gauss quads: L = 10 cm G 1 k. Gauss/cm Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 20

Pass up + Pass down 0 -2 DISP_X&Y[m] BETA_X&Y[m] 20 2 Pass-1 ‘up’ 0 BETA_X 5 Me. V BETA_Y DISP_X DISP_Y 50. 8316 71 Me. V 137 Me. V 0 -2 DISP_X&Y[m] BETA_X&Y[m] 20 2 Pass-1 ‘down’ 0 BETA_X BETA_Y 137 Me. V DISP_X DISP_Y 50. 8316 5 Me. V 71 Me. V Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 21

Vigorous R&D Program towards TDR Linear lattice optimization Initial magnet specs Momentum acceptance and longitudinal match End-to-End simulation with synchrotron radiation, CSR and micro -bunching Correction of nonlinear aberrations (geometric & chromatic) with multipole magnets (sextupoles, octupoles) RF cavity design, HOM content BBU studies Injection line/chicane design Space-charge studies at injection Diagnostics & Instrumentation Multi-particle tracking studies of halo formation Final magnet specs Engineering design Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 22

What is CSR? § Mechanism: ü if a high brightness bunch is on a curved orbit, fields emitted from the tail can overtake and interact with the head of the bunch ü tail loses energy, head gains energy (tail-head effect) ü is an issue at all energies The results are a redistribution of particles (in an undesirable way): projected emittance growth projected energy spread growth centroid energy loss “bulk” Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 23

What is Microbunching? Initial density modulation can induce energy modulation due to the presence of short-range wakefields (e. g. LSC or CSR) The energy modulation can be converted to density modulation via the M 56 in the beamline This ‘loop’ may result in an enhancement of the initial density modulation microbunching instability current l gain z impedance l M 56 energy z Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 24

Why is it Important in ERLs? § Microbunching is a relatively new collective effect § Lots of work has been done investigating chicanes § Recent efforts address CSR and microbunching in recirculation arcs § ERLs have potential to seed microbunching instability ü low injection energy (efficiency) ü multiple linac sections ü lots of bending (merger, arcs, chicanes) § ERL-driven light sources (short bunch, high peak current) must contend with microbunching, but so do other applications (e. g. bunched beam cooler) Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 25

Microbunching Gain in Arc 1 § Multi-pass machines are particularly prone to microbunching ü care must be taken to limit modulation of M 56 in spreaders/arcs/recombiners § Multiplying the gain for each individual arc often underestimates the total gain ü need to do end-to-end gain calculation C. Tennant Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 26

Microbunching Gain in Arc 1 § The lattice minimizes transverse emittance growth due to CSR • however, the longitudinal phase space will still be affected by the CSR wake • care must be taken during energy recovery when the bunch is adiabatically antidamped arc entrance arc exit C. Tennant Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 27

Summary PERLE is a unique ‘test bed’ for next generation of high power ERLs PERLE@Orsay (400 Me. V) ‘lean design’, fewer magnet varieties, 1. 2 Tesla curved bends Multi-pass linac Optics in ER mode Linear lattice: 3 -pass ‘up’ + 3 -pass ‘down’ Arc Optics Choice Flexible Momentum Compaction Optics Modular Architecture Vertical switchyard Matching sections: Linac-Switchyard-Arc Dipole and Quad design Vigorous R&D Program Ahead… CSR/Microbunching studies underway Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 28

Thank you! Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 29

Special Thanks to: Oliver Brüning Erk Jensen Max Klein and Alessandra Valloni Thomas Jefferson National Accelerator Facility Operated by JSA for the U. S. Department of Energy Alex Bogacz PERLE Collaboration Mtg. Daresbury, UK, Jan. 15 -16, 2018 30