1. Progress on Non-linear Beam Dynamic Study
Vasiliy Morozov, Fanglei Lin, Yuri Nosochkov, Min-Huey Wang,
Guohui Wei, Yuhong Zhang
JLEIC R&D Meeting, March 16, 2017
F. Lin

2. Next Steps for Ion Collider Ring

3. Discussion on the layout
: Skew Quadrupole
0.3 m
0.3 m
0.5 m
0.4 m
0.2 m
1 m
The space for magnet layout seems tight, we need realistic advises from magnet group and mechanic group
Skew quads: 0.1 m; corrector: 0.2 m
Skew quads are just beside the FFQ without space.
Guohui Wei – presentation later today 3

4. Outline for Collaboration Meeting
Overview of chromaticity compensation schemes for the optimized baseline design of JLEIC electron collider ring that uses PEP-II magnets
Studied chromaticity compensation schemes for a TME-like-arc-cell electron collider ring design that uses new magnets
Chromaticity compensation for a FODO-arc-cell electron collider ring design that uses new magnets
Summary and Outlook

5. Optimized Baseline Design of e- Ring
An optimized baseline design of JLEIC electron collider ring, using PEP-II magnets, has been used for the non-linear beam dynamic study.
Circumference circumference of m=2x811.84m arcs + 2x280.92m straights
Chromaticities: (H,V) = (-113, -120)
The normalized uncoupled emittance at 5 GeV is 92 um-rad, the un-normalized one is 9.5 nm-rad. The normalized emittance in the baseline design is 138 um-rad, the un-normalized one is 14 nm-rad.

6. Summary of DA Results (Nov. 2016)
Compensation Options
x/x,0
x/σx , y/σy
(p/p)/σ
p/p=0
p/p=0.4%
Linear chromaticity compensation only (2 sext. families) (v1) 1
±20,±48
0,0
  9
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
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
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
Linear compensation (2 sext. families) + SuperB based local compensation scheme (scheme-3 with large bending angle dipoles)
1.4
±25,±60
±10,±15
Linear compensation (2 sext. families) + SuperB based local compensation scheme (scheme-6 with small bending angle dipoles, ring geometry is not matched)
0.93
±23,±72
±7,±26
11
Simulation results were presented in JLEIC collaboration meeting fall 2016

7. Plan (Dec. 2016)
Optimize the superB-like compensation scheme for a better emittance control (done)
Match the ring’s geometry (with new-magnet TME-like-arc-cell first) and check the DA
Good, do the following studies (for the new magnet FODO-arc-cell ring too?)
Bad, go back to the new magnet FODO-arc-cell ring and do the following studies
Done. The answer is bad, or not good enough. Will check the FODO-arc-cell ring.
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, develop a correction scheme using BPMs and correctors included (or added/removed), 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

8. Complete e- Ring Optics
SuperB-like Chromaticity Compensation (SBCC) blocks are implemented in a TME-like-arc-cell electron collider ring design using new magnets
Circumference m = 2 x m arcs + 2 x m straights
Normalized 5 GeV: 30.9 um-rad for w/o SBCCs and 29.4 um-rad for w/ SBCCs, un-normalized ones are 3.2 and 3 nm-rad, respectively IP
SBCC

9. Optics of TME-like Cell and SBCC
TME-like arc cell (using new magnets)
Length 22.8 m (same as ion ring arc cell)
arc bending radius m (same as in the baseline)
270/90 x/y betatron phase advance
Dipole
Length 4 m, bending angle 2.1
12 GeV
Sagitta 1.83 cm
Quadrupole
Length 0.56 m
24 12 GeV
arc IP
SuperB-like chromaticity compensation block
Short dipoles + small angle per dipole => low H-function
Relatively large beta functions at the sextupole locations
180 phase advance between the two focusing sextupoles, same to the defocusing sextupoles
Optimized phase advance (np + Dm) between SBCC sextupoles and FFQs

10. Results of Each Scheme
The detail of results will be presented in the coming JLEIC collaboration meeting by Yuri Nosochkov (SLAC).

11. Summary of DA Results (so far)
Compensation Options
Arc Sexts
K2 (1/m3)
x , x
x/σx , y/σy
(p/p)/σ
=0
=0.4%
4 high-beta SBCCs, 2 SBCCs for FFQs chromatic corrections, 2 SBCCs unused, interleaved sexts in arcs for linear chromaticity corrections
14.71,
-159, -196
-9, +5
4 high-beta SBCCs for FFQs chromatic corrections, interleaved sexts in arcs for linear chromaticity corrections
13.93,
8.8, 23
7, 12
-12, +12
4 high-beta SBCCs for FFQs chromatic corrections, non-interleaved sexts in arcs for linear chromaticity corrections
27.86,
-5, +5
4 high-beta SBCCs, 2 SBCCs for FFQs chromatic corrections, 2 SBCCs for local SBCC chromatic correction, interleaved sexts, but new sexts locations, in arcs for linear chromaticity corrections
43.81, -9.61
2 high-beta SBCCs for FFQs chromatic corrections, 2 low-beta SBCCs (for less contribution of chromaticity), interleaved sexts in arcs for linear chromaticity corrections
10.13,
-145, -169
15, 29
7, 14
2 high-beta SBCCs for FFQs chromatic corrections, 2 low-beta SBCCs (for less contribution of chromaticity), interleaved sexts, but new sexts locations, in arcs for linear chromaticity corrections
30.53, -7.25
-9, +9
No emittance growth in all above schemes ! But DA may not be large enough !

12. Optics of FODO Cell and SBCC
FODO arc cell (using new magnets)
Length 11.4 m (half of ion ring arc cell)
arc bending radius m (same as in the baseline)
108/108 x/y betatron phase advance
Dipole
Length 3.6 m, bending angle 2.1
12 GeV
Sagitta 1.65 cm
Quadrupole
Length 0.56 m
21 12 GeV
New
arc IP
SuperB-like chromaticity compensation block
Short dipoles + small angle per dipole => low H-function
Relatively large beta functions at the sextupole locations
180 phase advance between the two focusing sextupoles, same to the defocusing sextupoles
Optimized phase advance (np + Dm) between SBCC sextupoles and FFQs