| Paper | Title | Page |
|---|---|---|
| SUPB006 | Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility | 10 |
|
||
| In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software. | ||
| SUPB031 | The Nonresonant Perturbation Theory Based Field Measurement and Tuning of a Linac Accelerating Structure | 80 |
|
||
| Assisted by the bead pull technique, the nonresonant perturbation theory is applied for measuring and tuning the field of the linac accelerating structure. The method is capable of making non-touch measurement, amplitude and phase diagnostics, real time mismatch feedback and field tuning. Main considerations on measurement system and of C-band traveling-wave structure are described, the bead pull measurement and the tuning of the C-band traveling-wave linac accelerating structure are presented. | ||
| SUPB032 | The C-band RF Pulse Compression for Soft XFEL at SINAP | 83 |
|
||
| A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities. | ||
| MOPB007 | Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility | 189 |
|
||
| The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance. | ||
| MOPB086 | The Nonresonant Perturbation Theory Based Field Measurement and Tuning of a Linac Accelerating Structure | 375 |
|
||
| Assisted by the bead pull technique, the nonresonant perturbation theory is applied for measuring and tuning the field of the linac accelerating structure. The method is capable of making non-touch measurement, amplitude and phase diagnostics, real time mismatch feedback and field tuning. Main considerations on measurement system and of C-band traveling-wave structure are described, the bead pull measurement and the tuning of the C-band traveling-wave linac accelerating structure are presented. | ||
| TUPB018 | Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility | 513 |
|
||
| In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software. | ||
| TUPB021 | Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability | 522 |
|
||
|
The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions.
[1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008) [2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999) [3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004) |
||
| TUPB022 | A Passive Linearizer for Bunch Compression | 525 |
|
||
| In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown. | ||
| TUPB097 | The C-band RF Pulse Compression for Soft XFEL at SINAP | 687 |
|
||
| A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities. | ||