| Paper |
Title |
Page |
| TUPC061 |
Laser Wire Beam Profile Monitor at Spallation Neutron Source (SNS)
|
1197 |
| |
- Y. Liu, S. Assadi, W. P. Grice, C. D. Long
ORNL, Oak Ridge, Tennessee
|
|
| |
We report the first measurement of a hydrogen ion beam profile in the superconducting linear accelerator (SCL) at the Spallation Neutron Source (SNS) with a laser wire beam profile monitor. The advantage of the laser beam profile monitor includes non-invasive measurement, longitudinal beam scan and multiple station measurement capabilities. A Q-switched Nd:YAG laser at 1.06 μm is used to detach electrons from hydrogen ions. The laser has a repetition rate of 30 Hz and a pulse width of 7 ns. Typical pulse energies are 50 - 200 mJ. The laser is physically located outside the SCL tunnel and the ion beam profiles are measured at 9 different locations covering the entire SCL region (~ 200 m). At SNS the beam structure consists of 50 ps long micropulses separation by ~ 2.5 ns and gated into macropulses of up to 1 ms long. The firing of the laser flashlamps is synchronized to the macropulse timing. The collection magnet bends the photodetached electrons out of the beam and into a Faraday cup. Both horizontal and vertical beam profiles (typical width: 2 - 4 mm) can be measured with a resolution of 4 um. Transverse beam scans can be performed throughout the macropulse.
|
|
| THPP139 |
Stainless Steel Vacuum Chambers for the SSRF Storage Ring
|
3688 |
| |
- D. K. Jiang, Y. L. Chen, Y. Liu, Y. Lu, Y. M. Wen, L. Yin, Z. T. Zhao
SINAP, Shanghai
- G. D. Liu, Z. A. Zheng
Shanghai Sanjin Vacuum Equipment Ltd. Company, Shanghai
|
|
| |
Stainless steel 316LN plate was adopted as main material for SSRF storage ring vacuum chambers and ante-chamber structure was used just as other 3rd light source. The analysis for the deformation of the chambers under atmospheric pressure and the thermal situation under synchrotron radiation were done with ANASYS program. Many problems on the structure design and fabrication technique were revealed and suitable solving methods were found in the process of development and manufacture of nine chamber prototypes. Deep draw die was used to form the chambers’ figuration. Wire cutting and CNC machining were used to manufacture the main components. The flatness tolerance, straightness tolerance and the deformation of the chambers under atmospheric pressure were all less than 1mm. After annealed in the vacuum furnace at 850℃, the magnetic permeability of welding seal was reduced from 2.5 to 1.02, the residual stress was deleted, and the vacuum performance was improved. Now SSRF vacuum system is being operated very well. The average pressure without beam is about 2.5×10-8 Pa and the average pressure with beam of 3GeV/100mA is about 8×10-7 Pa.
|
|
| THPP144 |
The Vacuum System for SSRF Storage Ring
|
3702 |
| |
- D. K. Jiang, L. Chen, Y. L. Chen, W. Li, Y. Liu, Y. Lu, H. Zhang
SINAP, Shanghai
|
|
| |
The vacuum system for SSRF was completed at the end of 2007 and has run for one month without any malfunction. The vacuum chamber for the storage ring made from stainless steel 316LN plate. About 180 absorbers and 80 RF bellows with a single finger structure are used for the storage ring. About 292 compound pumps (SIP+NEG) and 188 TSP are used. After the vacuum system in the straight section of a cell and all pumps in the bending section were baked, the ultimate pressure reached 2×10－8 Pa. Normally, the temperature raise on the chambers any where is less than 4℃ with current 100mA. The temperature raise of the cooling water for all absorbers is less than 3℃. The vacuum control and interlock system are on working order.
|
|