1. Summary of JLEIC Electron Ring Nonlinear Dynamics Studies
Fanglei Lin, Yuri Nosochkov, Vasiliy Morozov, Guohui Wei, Yuhong Zhang
August 23, 2016
F. Lin

2. Suggested Plan for Electron Ring Studies
Short/Medium-term goals:
Finish the study of SuperB compensation scheme
Determine the best compensation scheme(s) for the electron ring considering control of the emittance growth
Replace the thin lens phase/tune trombones with actual quadrupole adjustment and verify the chromatic correction performance
Optimize betatron tunes by doing the tune scan
Study effects of misalignment and field errors on the dynamic aperture and develop a correction scheme by using BPMs and correctors included (or added/removed if needed), specify alignment and strength error tolerances.
Study impact of multipole fields in regular magnets (using PEP-II specs) on the dynamic aperture
Determine FFQ multipole tolerances following the same procedure as for the ion collider ring
Long-term goals:
Consider compensating both up- and downstream FFQs using the nearest arc at the expense of chromatic smear at the IP
Evaluate the need for geometric sextupoles and octupoles

3. Super B Scheme-3

4. Nonlinear Dynamics Study Results
Compensation Scheme
x/x,0
x/σx , y/σy
(p/p)/σp/p
L/L0
Touschek lifetime (h)
p/p=0
p/p=0.4%
Linear chromaticity compensation only (2 sext. families) (v1) 1
±20,±48
0,0
  9
128
Linear compensation (2 sext. families) + interleaved –I sextupole pairs for FF correction (2 pairs in each plane in each arc) (v1a)
Linear compensation (2 sext. families) + non-interleaved –I sextupole pairs (1 pair in each plane in each arc) & strength and phase adjustments for FF correction (v1b3)
2.1
±15,±40
±4.5,±10
  9
308
Linear compensation (2 sext. families) + non-interleaved –I sextupole pairs & strength (1 pair in each plane in each arc) and phase adjustments for FF correction + beta function control at –I pairs to lower emittance growth (v1d2)
1.7
±17,±41
±5,±10
236
Linear compensation (2 sext. families) + compact chromaticity compensation blocks (CCBs) in arcs for FF correction & strength and phase adjustments for FF correction (v)
±8.5,±18
±5,±7.3
240
Linear compensation (2 sext. families) + SuperB based local compensation scheme (scheme-3)
1.4
±25,±60
±10,±15
214
x,0 is the reduced uncoupled horizontal emittance 9.5nm-rad, not the emittance in the baseline design 14nm-rad.
9.5nm-rad is from MADX w/o dividing dipoles to slides, 8.9nm-rad is from MAD8 and ELEGANT w/ dividing dipoles to slides

5. Back Up

6. Chromatic Tune Shift Only linear chrom sext
Courtesy of Yuri Nosochkov
Only linear chrom sext
Distributed interleaved –I pairs
Compact CCB
Non-interleaved –I pairs
and lower emittance
Phase advance from the “non-linear” sextupoles to IP is set to n+  /2.
Larger momentum range is achieved with compact CCB and non-interleaved –I pairs.

7. Chromatic * Only linear chrom sext Distributed interleaved –I pairs
Courtesy of Yuri Nosochkov
Only linear chrom sext
Distributed interleaved –I pairs
Compact CCB
Non-interleaved –I pairs
and lower emittance
Better correction with compact CCB and non-interleaved –I pairs.

8. Dynamic Aperture Only linear chrom sext
Courtesy of Min-Huey Wang
Only linear chrom sext
Distributed interleaved –I pairs
Compact CCB
Non-interleaved –I pairs
and lower emittance
±20σx
±15σx
±17σx
±8.5σx

9. Luminosity vs. Chromatic *
Luminosity formula
Integrated Luminosity ratio considering chromatic * due to the momentum spread
here
Consider
Assume ion chromatic * dose not change too much