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Beam injection section into the storage ring (right)
from SSBT (left) |
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25m-long undulator |
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The storage ring is a circular accelerator for light sources and its circumference is 1436 m long. A normal cell is about 30 m long and composed of 2 bending magnets, 10 quadrupole magnets and 7 sextupole magnets (Double-Bend Achromat, DBA). There is a straight section between normal cells and it is used for the installation of an insertion device (ID), RF acceleration cavities, beam injection system, beam diagnostic systems, etc. The total number of straight sections is 44. Synchrotron radiation from a bending magnet is extracted at the upper course of the electron orbit in the magnet, and the specifications on the electron beams at the upstream bending magnet (B1) are slightly different from those at the downstream bending magnet (B2). The harmonic number (number of buckets) is 2436. We can select any bucket into which electron bunches are injected. We operate the storage ring with several filling patterns.
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| beam energy |
< 8 GeV |
| circumference |
1435.95 m |
| nominal stored current |
100 mA |
| critical photon energy / wavelength |
28.9 keV / 0.429 Å |
| natural emittance |
2.4 nm•rad |
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horizontal / vertical
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| 316 µm / 4.9 µm |
| 333 µm / 6.8 µm |
| 94 µm / 11.6 µm |
| 100 µm / 12.2 µm |
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horizontal / vertical
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| 8.8 µrad / 1.0 µrad |
| 8.3 µrad / 0.7 µrad |
| 58 µrad / 0.5 µrad |
| 68 µrad / 0.5 µrad |
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| coupling (κ) |
0.2 % |
| bunch length (σ) |
13 ps at 0 mA |
| bunch impurity |
< 5 x 10-10 |
beam orbit stability
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| fast (0.1 ~ 200Hz) |
slow (< 0.1Hz)
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horizontal / vertical
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| ~4µm (rms) / ~1µm (rms) |
1~2µm (rms) /week / 2~3µm (rms) /week
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| beam lifetime |
| (a) multi-bunch |
| (b) single bunch |
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| vacuum pressure of the storage ring |
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| 10-8 Pa ~ 10-6 Pa |
| 10-9 Pa ~ 10-8 Pa |
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| betatron functions and dispersion |
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| lattice |
Double-Bend Achromat
HHLV (High Horizontal Low Vertical beta functions) + 4LSS (Long Straight Sections) |
| number of cells |
44 cells (36 normal cells, 8 matching cells) |
| number of bending magnets |
| curvature radius |
| magnetic field |
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| number of quadrupole magnets (per cell) |
| normal cell |
| matching cell |
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| length of straight section |
| normal cell |
| long straight section |
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horizontal / vertical
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| 31.2 m / 5.0 m |
| 34.5 m / 9.7 m |
| 2.9 m / 28.0 m |
| 2.4 m / 30.9 m |
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horizontal / vertical
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| 0 / 0 |
| 0 / 0 |
| 1.53 / -0.55 |
| 1.32 / 0.62 |
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horizontal / vertical
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| 0.032 m-1 / 0.20 m-1 |
| 0.029 m-1 / 0.10 m-1 |
| 1.13 m-1 / 0.047 m-1 |
| 1.13 m-1 / 0.045 m-1 |
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| 0.146 m |
| 0.153 m |
| 0.039 m |
| 0.059 m |
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| betatron tune |
horizontal : 41.14 / vertical : 19.35 |
| energy spread |
0.11 % |
| momentum compaction (α) |
1.59 x 10-4 |
| chromaticity |
horizontal : 1 / vertical : 2 |
| revolution frequency / revolution time |
208.8 kHz / 4.79 µs |
| RF frequency |
508.58 MHz |
| harmonic number |
2436 (2x2x3x7x29) |
| maximum acceleration voltage |
16 MV |
radiation loss per turn (by bending magnets)
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8.91 MV |
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Last modified
2016-02-25 14:06
