20170602-JleicIonIntegration

Jun 2 2017 JLEIC Ion Integration Meeting

Andrew Hutton and his student Andrew Dotson have need of canonical ion collider ring harmonic numbers.
- There is some confusion about the official baseline numbers, with inconsistencies between
  - the Jun 29 2016 Study of Beam Synchronization at JLEIC arxiv note (h=3422-3437)
  - Jiquan's fall 2016 collaboration talk (h=3584)
  - Shaoheng's Ion ring RF parameters as linked in the Ion Collider Ring Requirements and Parameters area of the JLEIC Baseline Parameters wiki. (h=6832?)
Jiquan is working on a tech note based on a spreadsheet that has ion collider h=3584-3592 (with stretch goal to 3594).
- h=3584 baseline is consistent with the fall collaboration meeting slides (slide 5), with h=28 split 2⁷ times.
Path forward:
- Identify Jiquan as owner
- Establish consensus ion ring circumference (latest appears to be ~2300m from Yuhong/Vasiliy/Fanglei)
- Establish consensus RF parameters consistent with 2ⁿ bunch splitting.
  - With 2300m, Jiquan has suggested 3648 (C=2295m) or 3712 (C=2336m) to keep 2⁶ divisibility.
- Update appropriate documentation, particularly JLEIC Baseline Parameters wiki.
- Disseminate expectation that JLEIC Baseline Parameters wiki should be current canonical parameter information.

Polarized ion source discussion (Amy)
- Followup from discussions at spring collaboration meeting
- Amy/Zack: First telecon scheduled Wed Jun 14 15:00
ANL visit (Todd, Tue Jul 11)
- Coordinating visit, meeting plan with Brahim/Zack
- Brahim: summer student extending linac to high energy
- Linac lattice baseline/parameter area to be shared via Dropbox, reflected in JLEIC Baseline Parameters wiki
- Linac/Booster optimal Pb charge state (67+?) (see previous meeting)

Done:
- Using default working point (7.517,5.493) and bare chromaticities (-13.9,-11.5)
- Installed sextupole families, chromaticities tuned to +1,+1
- No particle loss seen at injection, cooling; some particle loss of o(percent) seen at extraction
- Bunch length presently short (meters) per Todd's Booster parameter spreadsheet
To Do:
- Evaluate alternative working point to mitigate extraction losses
- Develop h=1 RF ramp parameters, start simulating at extraction

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)

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)

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

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