1. Possibility of Recuperating PEP-II HER Magnets for MEIC Electron Ring (II)
Fanglei Lin, Andrew Hutton, Vasiliy S. Morozov, Yuhong Zhang
MEIC R&D Meeting, JLab, August 14, 2014
F. Lin

2. MEIC FODO & TME-like Cell
MEIC FODO cell
MEIC TME-like cell
Phase advance: 1.5(H), 0.5(V)
Every 2 cells generate 3 and  phase advance in horizontal and vertical plane, respectively
Maximum sextupole pole-tip field at 4.5cm aperture radius is ~ 0.5 T for compensation of cell’s chromaticities (PEP or PEP-II sextupoles can be reused in MEIC )
Phase advance: 135(H & V)
Every 4 cells generate 3 phase advance in both horizontal and vertical planes
Maximum sextupole pole-tip field at 4.5cm aperture radius is ~ 0.2 T for compensation of cell’s chromaticities

3. PEP-II HER vs. MEIC Arc Cell
Parameters
Unit
PEP-II HER
MEIC FODO cell
(135 phase advance)
MEIC TME-like cell
(1.5/0.5 pha. adv.)
MEIC TME-like cell (1.5/0.5 pha. adv.)
Energy
GeV 9 12 5
Dipole length m
5.4
Bending angle
deg
1.875
4.108
4.85
4.45
Bending radius
165.0
75.3 (57.9)
75.3
63.7
69.5
Magnetic field T
0.1819
0.5314
0.2214
0.6280
0.2617
0.5757
0.2399
Quad length
0.7185
0.37
0.7/0.6/0.6
Field gradient
T/m
5.48
29.5
28/29/29
12/12/12
Aperture radius cm ~5
4.5
Cell length
15.2
13.78
17.36
Number of cell
16*6 52 44 48
Arc length
243.2*6
(673.92)
716.56
763.84
833.28
Arc 43 90
160 C 83
173
308
Nor. emittance um
845
2746 (438)
199 (31.7)
312 (438)
22.6 (31.7)
240 (438)
17.4 (31.7)
Sagitta R
2.2
4.8
5.7
5.2
* The current values are given in parenthesis

4. Some Practical Considerations
Orbit curvature changes inside the dipoles  limit maximum sagitta R
PEP-II FODO cell
MEIC FODO cell
MEIC TME-like cell
optimal curvature   4

5. Back Up

6. MEIC’s e-Ring Current Equilibrium Emittance
Normalized Equilibrium Horizontal Emittance εxN (μm)
Energy (GeV) 3 5 6 7 8 9 10 11 12
Arc FODO (120 phase advance)
6.8
31.7
54.7
86.9
129.8
184.8
253.5
337.4
438.2
Arc (FODO + spin rotators)
11.8
54.5
94.2
149.6
223.2
317.8
435.9
580.4
753.4
Whole ring (Arc + IR)
15.4
71.3
123.2
195.7
292.1
415.8
570.4
759.2
985.7
Beam energy
Gev 3 5 6 7 8 9 10 11 12
Beam current A
2.0
1.1
0.65
0.4
0.26
0.18
0.13
Total SR power MW
0.49
3.82
5.28
5.38
5.43
5.35
5.37
5.49
Linear SR power density
kW/m
1.02
7.87
10.88
11.08
11.10
11.01
11.06
11.31
Energy loss per turn
MeV
0.17
1.27
2.64
4.89
13.37
29.84
Energy spread
10-3
0.34
0.56
0.68
0.79
1.01
1.24
Longitudinal damping time ms
83.6
18.1
10.4
6.6
3.1
1.7

7. PEP-II HER vs. MEIC Arc Cell
Parameters
Unit
PEP-II HER
MEIC FODO cell
MEIC TME-like cell
Energy
GeV 9 12 5
Dipole length m
5.4
Bending angle
deg
1.875
4.272
5.34
Bending radius
165.0
72.4 (57.9)
72.4
57.9 (57.9)
57.9
Magnetic field T
0.1819
0.5527
0.4145
0.2303
0.6908
0.2878
Quad length
0.45
0.35
0.5/0.6/0.6
Field gradient
T/m
9.79 29 22
27/28/26
11/12/11
Aperture radius cm
3.6 (?)
4.5
FODO length
15.2
13.74
17.16
Number of FODO
16*6 50 40
Arc length
243.2*6
687 (673.92)
687
686.4
Normalized emittance um
845
3478 (438)
1446 (184.8)
252 (31.7)
951 (438)
69 (31.7)
SR power density
kW/m
7.23 (11.31)
7.04 (11.01)
5.03 (7.87)
11.31
7.87
Total SR power MW
4.39 (5.49)
4.28 (5.35)
3.05 (3.82)
5.49
3.82
* The current values are given in parenthesis

8. Some Practical Considerations
Orbit curvature changes inside the dipoles  limit maximum sagitta R
PEP-II FODO cell
MEIC FODO cell
MEIC TME-like cell
optimal curvature   8