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Design Optimization of MEIC Ion Linac & Pre-Booster

Design Optimization of MEIC Ion Linac & Pre-Booster. B. Mustapha, Z. Conway, B. Erdelyi and P. Ostroumov ANL & NIU MEIC Collaboration Meeting JLab, October 5-7, 2015. Content. Purpose: More Compact Design of the Ion Injector  Cost Reduction The Original Linac Design

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Design Optimization of MEIC Ion Linac & Pre-Booster

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  1. Design Optimization of MEIC Ion Linac & Pre-Booster B. Mustapha, Z. Conway, B. Erdelyi and P. Ostroumov ANL & NIU MEIC Collaboration Meeting JLab, October 5-7, 2015

  2. Content • Purpose: More Compact Design of the Ion Injector  Cost Reduction • The Original Linac Design • A New More Compact Linac Design & Potential Cost Savings • Key Components / Parameters of the New Linac Design • Normal Conducting RFQ and IH Structures • High Performance Superconducting QWRs and HWRs • Optimized Stripping Energy and Voltage Profile • RF Power & Tuning • Lower Injection Energy to the Pre-booster/Booster • A New More Compact Pre-Booster Design • Summary & Future Work B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  3. Original Linac Design (2012): Layout & Main Features • Warm front-end up to ~ 5 MeV/u for all ions • SC QWR section up to 13 MeV/u for Pb ions • A stripper for heavy ions for more effective acceleration: Pb28+  67+ • SC high-energy section (QWR + HWR) up to 280 MeV for protons and 100 MeV/u for Pb ions • Total linac length of ~ 130 m with a total pulsed power of 560 kW B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  4. New Linac Design (2015): Layout & Main Features • The same warm front-end up to ~ 5 MeV/u for all ions • A single high-performance QWR module up to 8.2 MeV/u for Pb ions • A stripper for heavy ions for more effective acceleration: Pb30+  61+ • High-energy SC section (QWR + HWR) up to 130 MeV for protons and 42 MeV/u for Pb ions • Total linac length of ~ 55 m with a total pulsed power of 260 kW B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  5. Comparison of Linac Designs and Potential Cost Savings VS • The new design is ~ 1/3 the construction cost B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  6. Key Components / Parameters of the New Linac Design • A Normal Conducting Front-End: RFQ and IH Structures • High-Performance Superconducting QWRs and HWRs • Optimized Stripping & Voltage for Heavy-ions • Pulsed RF Power & Tuning • Lower Injection Energy to the Pre-booster/Booster B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  7. Normal Conducting Front-End: RFQ + IH Structure BNL EBIS Injector 100 MHz IH Structure ATLAS 60 MHz 4-vane RFQ • A 100 MHz 4-rod pulsed RFQ also exist at BNL B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  8. High-Performance QWRs developed at ANL for ATLAS ATLAS 72MHz QWR Conditioning • A single QWR is capable of delivering 4 MV voltage @ Epeak ~ 60 MV/m and Bpeak ~ 90 mT B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  9. High-Performance HWRs developed at ANL for FNAL FNAL/PXIE - 162 MHz HWR • A single HWR is capable of delivering 3 MV voltage @ Epeak ~ 60 MV/m and Bpeak ~ 70 mT B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  10. Preliminary QWR and HWR Designs for MEIC Linac MEIC QWR Design MEIC HWR Design B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  11. Optimized Stripping Energy and Cavity Voltage Profile SC Cavity Voltage Profile (Optimized for Pb ions) Total Linac Voltage vs. Stripping Energy (Optimized for Pb ions) • Stripping energy optimized for lowest total voltage requirement • SC Cavity Voltage profile optimized for lead ions • SC Cavity re-phasing produces much higher energy for protons B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  12. RF Power & Tuning • Pulsed Operations: ~ 10% duty cycle  Lower dynamic load • Pulsed solid state RF amplifiers are less costly than for CW • Additional RF power may be needed to extend the frequency tuning band width • Lorentz detuning can be controlled by initial frequency offset between stand-alone and driven modes • Due to pulsed operation, different mechanical modes are exited leading to greater micro-phonics than in CW mode • Piezo tuner can be used for HWR to control micro-phonics, QWR will need more studies due to pendulum oscillation mode B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  13. Lower Injection Energy to the Pre-booster/Booster • Lower output energy of the linac, 130 MeV protons & 42 MeV/u for Pb • More important space charge (SC) effects in the following pre-booster/booster • SC effects are mitigated by the appropriate design and beam formation scheme of the pre-booster/booster • The original 280 MeV injection energy was conservative in terms of space charge  possible to lower the injection energy B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  14. Original Pre-booster Design (2012) From Linac • Figure-8 design to preserve beam polarization • Below transition energy: 3 GeV for protons, 670 MeV/u for Pb ions • 234 m circumference with adequate space for insertions: e-cooling, RF system, injection, extraction, correction and collimation B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  15. Design Iterations for a more Compact Pre-booster   Design criteria: • Half the circumference • Not cross γ transition B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  16. New More Compact Pre-booster Design (2015) • A 120 m long Octagonal Design • Same injection and extraction features as the original design • Four dispersion-free sections • Will require Siberian snakes for polarization • Injects to large booster with storage ring B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  17. Comparison of Pre-Booster Designs and Cost Savings VS • The new design is ~ 1/2 the construction cost B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  18. Design Parameters and Optics of the New Pre-booster • Keeping pre-booster energy @ 3 GeV  Low field for Siberian snakes B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  19. Space Charge & Tune Shift In New Pre-booster Design • SC tune shifts in new pre-booster design are below 0.25 for the same number of ions as the original design • More detailed studies of SC are needed to better control emittance growth  Beam simulations using MAD and COSY • Due to lower ion energy and high charge state, dynamic vacuum instability may be an issue (ex. GSI studied this effect) B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

  20. Summary & Future Work • A New more compact lower energy Linac design • Less number of cavities, much shorter tunnel • ~ 1/3 construction cost of the original design • A new more compact Pre-booster design • Less number of magnets, half the circumference • ~ 1/2 construction cost of the original design • The 3 GeV octagonal pre-booster will / could use • Low field Siberian snakes to control ion polarization • Electron storage ring as ion large booster? (Derbenev & Ostroumov) • Future work • Space charge studies in pre-booster • Injection and beam formation schemes • … B. Mustapha Design Optimization of Ion Linac & Pre-booster MEIC Collaboration Meeting, Jlab, October 5-7, 2015

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