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EMMA – Accelerator Overview

EMMA – Accelerator Overview. Hywel Owen ASTeC Daresbury Laboratory. Presentation Contents. EMMA Parameters overview ERLP as an injector Transfer Line Components – Magnets and RF Cavities Injection/Extraction Outstanding Issues. EMMA Parameters. Baseline lattice conform-pc-spec-0001v0.4

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EMMA – Accelerator Overview

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  1. EMMA – Accelerator Overview Hywel Owen ASTeC Daresbury Laboratory

  2. Presentation Contents • EMMA Parameters overview • ERLP as an injector • Transfer Line • Components – Magnets and RF Cavities • Injection/Extraction • Outstanding Issues

  3. EMMA Parameters • Baseline lattice • conform-pc-spec-0001v0.4 • (Lattice from 13 December) • Notes: • Variable injection energy • Variable operating point • Variable RF voltage • Would like variable RF frequency, but range is limited • Orbit swing depends on operating point Parameter Value Energy range 10 – 20 MeV Number of cells 42 Lattice F/D Doublet Cell length 394.594 mm Circumference 16572.941 mm Injected emittance 5-20 mm mrad (norm.) Model acceptance 3000 mm mrad (norm.) Orbit swing 3 cm Repetition rate 1, 5, 20 Hz RF Frequency 1.3 GHz (1.2974 to 1.3014) RF voltage 20 – 180/120 kV/cavity (14/21 cavs) Number of RF cavs 14/21 (to be agreed)

  4. EMMA Layout 7 x Girder Modules (6 cells) Plan View Shaped vacuum vessel

  5. EMMA Moving Quadrupole Solution Lateral movement + gradient change to adjust B and B’

  6. Outside of ring D Lq Ld F 0 A B C D cell 42 cell 1 cell 2 e- EMMA Geometry and Lattice (Scott Berg/Ben Shepherd)

  7. ERLP as an Injector for EMMA 2 x 1.3 GHz Superconducting Modules

  8. ERLP Parameters Parameter Value Nominal Gun Energy 350 keV Max. Booster Volts 8 MV TL 2 Energy 8.33 MeV Max. Linac Volts 26.67 MV Max. Energy 35 MeV Linac RF Frequency 1.300 GHz (+/- 1 MHz) Bunch Repetition Rate 81.25 MHz Bunch Spacing 12.3 ns Max Bunch Charge 80 pC (risk variable) Particles per Bunch 5 x 108 Bunches per Extraction Energy 10 to 20 MeV (need to check lower limit) Extraction Emittance 5-20 mm mrad (various issues)

  9. RF Cavities – Parameter Summary for 14 Cavity Option • Requirements for 14 Cavities • 120 kV/cav (min) • 160 kV/cav (a=1/6 expts) • 180 kV/cav (spec) • 360 kV/cav (ideal) • Located every 3rd straight • Fits with injection requirements • Non-smooth acceleration • 21 Cavities would require asymmetric placement – comments? • Required frequency tuning range is 3.96 MHz • 2 MHz with present tuners • More tuning range will reduce the available RF voltage (see RF talk)

  10. ERLP Operating as an Injector 8.35 MeV (standard) 1.65-11.65 MV (variable) 10-20 MeV (variable) 8.00 MV (2x4 MV) (standard) 0.35 MeV (fixed) Later we will need to consider adapted injector (post-4GLS construction)

  11. ERLP Photoinjector and Laser Commercial 500kV (350kV) 8mA DC Power Supply (Glassman Europe) Power supply and gun enveloped by 0.8 Bar SF6 environment ACCELERATOR HALL Shield wall LASER ROOM DC Gun Based on Jlab design Optical Table Booster Cavity Laser Beam Transport System

  12. ERLP Laser Pulse Output Characteristics Requirements The commercial solution

  13. ERLP Laser

  14. Injection and Extraction Timing Structure • Standard ERLP injector • 12.3 ns bunch spacing • Up to ~160 pC per bunch • Up to 2 bunches • Total charge <0.64 nC • Spec is 1 bunch, 80 pC • Pulse-stacking (adapted injector) • Down to 0.77 ns spacing • Up to ~80 pC per bunch • Up to 18 bunches • Total charge? • Costs more! Revolution time 55 ns (16.5 m) 12.3 ns (81.25 MHz) ~20 ns ~20 ns ~15 ns rise time fall time Injection flat-top time (top is not really flat) Revolution time 55 ns (16.5 m) 0.77 ns (1.3 GHz) ~20 ns max. 18 bunches ~20 ns ~15 ns rise time fall time Injection flat-top time RF frequency in injector can be changed by ~1 MHz – not enough!

  15. Injection at 10 Mev with one kick 0.15 R -ve kick 80 60 40 20 0 0 100 200 300 400 500 600 700 -20 -40 -60 -80 Injection Geometry – Single Kicker Option Note only 14 cavities now, not 21 Kicker Septum 2 parameters to control at injection point: position and angle Angle done with kicker Position done with upstream steerers This allows the incoming transfer line pipe to be fixed.

  16. F-D Doublet Tracking from Injection Point (B. Shepherd) Tracking performed through both magnets, at an offset of (x, z) = (-40.1, 139.2) and an angle of -6° in the y axis. Energy: 10MeV. The 42 electrons were emitted from an arc-shaped surface (top-down view shown). The radius of the arc is 10mm and the half-angle is 25°. So the particles come from a point source 10mm back from the arc surface, and are given a ‘kick’ of ±25° relative to the nominal trajectory. 0.15 rad  < -14.3°  > 18° To get electrons to the same distance from the nominal beam path on the outside of the ring requires a greater kick than on the inside. 16° 14° -9°

  17. Zgoubi Injection Tracking – 1 Kicker Solution (T. Yokoi) Kicker Septum

  18. Injection at Different Energies (T. Yokoi) ~3x too big!! Needs further study

  19. Range of quad movement Injection Geometry – F Quadrupole Cross-Section Need to be careful of edge fields here – either calculate or avoid this Incoming Beam Paths

  20. Range of quad movement Injection Geometry – D Quadrupole Cross-Section Vessel may need to be vertically larger here to allow full main aperture to be injected into Incoming Beam Paths

  21. Injection/extraction fields

  22. Vertical Injection through F-Quad Quadrupole movement Incoming Beam Paths

  23. + ve kick -ve kick Injection Geometry – 2-Kicker Option Note only 14 cavities now, not 21 Full D quadrupoles Kicker 1 Kicker 2 Steerers 2 parameters to control at injection point: position and angle Angle done with kicker Position done with upstream steerers This allows the incoming transfer line pipe to be fixed.

  24. Septum magnet to be placed in this long straight. Extraction Geometry Kicker Septum Steerers

  25. Possible Element Placement – Injection with 14 Cavities RF Cavity Kicker 1 Kicker 2 Injected Beam RF Cavity

  26. Transfer Line (C. Johnstone)

  27. ERLP and EMMA Survey Faro Laser Tracker Repeatability 1m +1 m /m Accuracy 10 m + 0.8 m /m Uncertainty ≈ 10 m /m Portable Robust Spatial Analyzer Metrology Software Error Simulations Multiple instruments/types Automation

  28. ERLP Hall Survey and Alignment Simulation of reference grid in SA 76 Grid reference points 40 Instrument positions Each point measured by a minimum of 3 instrument locations Faro Tracker Grid reference points

  29. ERLP Hall Survey Simulation Most points within +/- 50 m Worst point within +/- 82 m Instruments reference multiple points, worst Instrument position +/-13 m

  30. Outstanding Design Issues • Decision on injection and extraction geometries • Feasibility of kicker magnets • Effect of fringing fields (CST field calculation in progress) • Study of varying operating points and effect on injection • Final design of transfer line • Extraction line and diagnostics layout • Alignment tolerances (vertical correction?)

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