General Parameters
| Parameter | Value |
| Beam particle |
electron |
| Beam energy |
1.0-1.9 GeV |
| Injection energy |
1.0-1.9 GeV |
| Beam current (all operation is in top-off with ΔI/I <=0.3%) |
500 mA in multibunch mode
2 x 17.5 mA in two-bunch mode |
| Filling pattern (multibunch mode) |
256-320 bunches; possibility of one or two 5-6-mA "camshaft" bunches in filling gaps |
|
Bunch spacing: multibunch mode
|
2 ns |
|
Bunch spacing: two-bunch mode
|
328 ns |
| Circumference |
196.8 m |
| Number of straight sections |
12 |
| Current number of insertion devices |
11 |
| Radio frequency |
499.642 MHz |
| Beam size in straight sections, rms (1.9 GeV multibunch mode) |
301 microns horiz. x 10 microns vert. |
| Parameter | Value at 1.9 GeV |
|
Top-off injection rate: multibunch mode
|
1-1.5 mA/shot every 40-50 seconds |
|
Top-off injection rate: two-bunch mode*
|
0.4- 0.5 mA/shot every 25-30 seconds |
| Horizontal emittance |
6.3 nm-rad |
| Vertical emittance |
0.05 nm-rad |
| Energy spread (ΔE/E, rms) |
0.97 x 10-3† |
| Pulse Length (FWHM) |
70 ps‡ |
* Bunch cleaning is performed after every injection.
† Above 8 mA per bunch in two-bunch mode, the energy spread increases because of the microwave instability.
‡ In multibunch mode, the bunch length is deliberately increased using harmonic cavities to improve the beam lifetime. In two-bunch mode, the bunch length is current dependent. For 2 x 17.7 mA in top-off mode, it is about 60 ps.
The ALS has 12 straight sections and 12 arc-shaped sections, like the one shown above, containing bend magnets (B), quadrupoles (QFA, QDA, QF, and QD), and sextupoles (SF and SD). Three of the arc sections contain superconducting bend magnets (superbends) and therefore have a modified lattice as shown in the lower image.
Horizontal and Vertical Lattice Functions (α β, γ), Horizontal Dispersion Functions (ηx and ηx '), and 1-σ Beam Sizes (σ) and Divergences (σ') at Photon Source Points*
|
Beam Port
|
Angle [degrees]
|
Device
|
Axis
|
α
|
β[m]
|
γ[m-1]
|
ηx[m]
|
ηx '
|
σ
[µm]
|
σ'
[µrad]
|
|
BL x.0
|
0.0
|
insertion device
|
x
|
0.000
|
13.85
|
0.072
|
0.060
|
0.000
|
301.0
|
21.3
|
|
BL x.0
|
0.0
|
insertion device
|
y
|
0.000
|
2.26
|
0.443
|
|
|
10.6
|
4.7
|
|
BL x.1
|
6.3
|
bending magnet
|
x
|
-0.046
|
0.36
|
2.815
|
0.031
|
0.087
|
56.0
|
157.7
|
|
BL x.1
|
6.3
|
bending magnet
|
y
|
7.490
|
22.57
|
2.530
|
|
|
33.6
|
11.2
|
|
BL x.2
|
12.6
|
bending magnet
|
x
|
0.392
|
0.87
|
1.321
|
0.072
|
-0.052
|
101.8
|
104.4
|
|
BL x.2
|
12.6
|
bending magnet
|
y
|
-0.069
|
1.36
|
0.740
|
|
|
8.2
|
6.1
|
|
SB x.2
|
12.6
|
superbend magnet
|
x
|
0.037
|
0.95
|
1.054
|
0.057
|
-0.040
|
94.9
|
90.4
|
|
SB x.2
|
12.6
|
superbend magnet
|
y
|
0.050
|
1.22
|
0.821
|
|
|
7.8
|
6.4
|
|
BL x.3
|
17.4
|
bending magnet
|
x
|
-0.392
|
0.87
|
1.321
|
0.072
|
0.052
|
101.8
|
104.4
|
|
BL x.3
|
17.4
|
bending magnet
|
y
|
0.069
|
1.36
|
0.740
|
|
|
8.2
|
6.1
|
|
SB x.3
|
17.4
|
superbend magnet
|
x
|
-0.037
|
0.95
|
1.054
|
0.057
|
0.040
|
94.9
|
90.4
|
|
SB x.3
|
17.4
|
superbend magnet
|
y
|
-0.050
|
1.22
|
0.821
|
|
|
7.8
|
6.4
|
|
BL x.4
|
22.6
|
bending magnet
|
x
|
0.340
|
0.39
|
2.842
|
0.040
|
-0.109
|
63.1
|
170.4
|
|
BL x.4
|
22.6
|
bending magnet
|
y
|
-8.809
|
21.02
|
3.740
|
|
|
32.4
|
13.7
|
*These are generic lattice functions. There are small sector-to-sector variations in the parameters for a given source angle because of the distortion in the lattice functions of the superbends and the insertion devices. For more precise information, contact Christoph Steier (
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).
**Angle refers to the direction of the radiation from the source point, as shown below.
Normal Arc Lattice Function Plot
Superbend Arc Lattice Function Plot
|
