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Apr 21 2017 JLEIC Ion Integration Meeting

Report at R&D Meeting

  • Todd and Ed presented slides on Ion Injector Complex/Parameter Development at the Thu Apr 20 R&D Meeting
  • This summarized some recent work on Booster h=1 capture, ramp development, and Synergia space charge simulations

Booster h=1 Capture

  • Done:
    • 30 kV seems like the appropriate voltage for capturing initial coasting beam
    • 100 ms linear RF voltage ramp is workable (see presentation); faster may be feasible
    • esme simulation is relatively straightforward: RMS sigmaE/E goes from 3.1e-3 Gaussian (coasting) to 5.4e-3 parabolic (bunched)
    • Have tools in place to quickly make esme "movies"
  • To Do:
    • Develop consensus injection energy spread (Todd/Ed/Brahim)
    • Determine how fast <math>d^2B/dt^2</math> can be (Todd/Peter)
      • Emails ongoing: Peter raises interesting questions about snapback and dynamic superconducting magnet effects
    • Turn on injection longitudinal space charge for realistic intensities
      • Compare to Synergia (Ed/Todd)

Booster Ramping

  • Done:
    • Tools in place and under development for generating ramp parameters
    • f(RF) = 700 to 1030 kHz as input to RF design
    • h=1 through Booster to extraction appears appropriate
  • To Do:
    • Add esme ramp generation to RampDesigner tool
    • Start simulating early acceleration ramp with esme (space charge off, then on)
    • Pursue cooling evaluation at 2 GeV (bunched or coasting beam? Todd/He/Ed/...)
    • Evaluate addition of realistic impedances (Todd/Rui)

Booster Space Charge

  • Done:
    • Resolved chromatic resonance crossing problems in earlier simulations; reduced momentum spread
    • Using default working point (7.517,5.493) and bare chromaticities (-13.9,-11.5)
    • Injection emittance growth: x5-8 over hundreds of turns (~500 us)
    • Cooling porch emittance growth more modest (x1.5-2); no growth seen at extraction
  • To Do:

Linac/Booster Pb Charge State

  • ANL has mostly been simulating/optimizing the low energy linac (c.f. HB'16 talk/paper by Ostroumov)
    • This affects charge state and stripping optimization, but does not affect latest optimizations to handle RFQ heavy ion losses
    • Heavy ion source expected to have 1-2 pi mm-mrad normalized emittance; which is it?
  • Brahim has noted that 67+ may not be the optimal charge state for the baseline high energy linac
  • Brahim and Todd are continuing to discuss
    • Tradeoff of space charge vs stripping efficiency/pulse intensity
    • Todd's initial feeling is that this is a relatively flat optimization

Other Items

  • AOB

Reference Materials


  • TBD