| Paper | Title | Page |
|---|---|---|
TUPH04 |
Simulations of High Transformer Ratio High Brightness Plasma Wakefield Acceleration for Accelerator Parameters of SXFEL Facility at SINAP | |
|
||
|
High transformer ratio (HTR) Plasma Wakefield Accelerator (PWFA) based on shaped electron bunches is an important topic of plasma wakefield acceleration for future light sources and colliders [1]. To explore the possibility of implementing PWFA at SXFEL, we performed 3D PIC simulations using shaped electron beam parameters obtained by start-to-end beam line simulations [2]. The PIC simulations show that an average transformer ratio around 4 can be maintained for about 10 cm long low density plasma, and the energy gain of the trailing bunch eventually reaches 5.9 GeV. In addition, plasma density downramp injection has also been tested as a possible high brightness injection method for HTR acceleration, and preliminary results will be presented. Simulations and analysis are also performed to check the effects of transverse beam size on HTR high brightness acceleration.
[1] W. Lu, W. An, C. Huang et al., "High Transformer ratio PWFA for Applications on XFELs", Bulletin of the American Physical Society, 2009, 54. [2] Z. Wang, Z. T. Zhao et al., private communication. |
||
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
TUPH05 |
Experimental Observation of External Injection Acceleration by a Laser Produced Wake using a RF Photogun Based Linac | |
|
||
| External injection of beams into plasma accelerators and acceleration with minimal degradation of their quality provide a promising route to make plasma acceleration a realistic technology for applications. In the past two years, we have carried out a lot of preparatory work for the external injection acceleration experiment in Tsinghua University. An ultrafast TW Ti:sapphire laser system is synchronized with a 45 MeV RF photogun based linac with a sub-200fs (RMS) time jitter between the laser pulse and the electron bunch. Here we present the first-time observation of external injection acceleration by a laser produced linear wake. Stable 32-MeV, 1~2-pC electron beams from the linac were compressed by a Chicane, focused to a 200-um radius (RMS) and then injected into the linear wakefield excited by the 10TW, 30fs laser. The preliminary experimental results show that up to 20% electrons can be accelerated and the maximum energy gain reaches 0.35 MeV in a 6-mm long plasma by optimizing the plasma density and the laser focal plane position with respect to the plasma, corresponding to an average gradient of about 60 MV/m, which are in reasonable agreement with 3D PIC simulations. | ||
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
TUPH06 |
Experimental Demonstration of Energy-chirp Reduction by a Plasma Dechirper | |
|
||
|
The first experimental study is presented using a low density plasma dechirper to reduce a correlated energy chirp from the 41.5-MeV, 300-fs (RMS) beam at the linac in Tsinghua University. The plasma dechirper operates through the interaction of the electron bunch with its near linear self-wake to dechirp itself, leading to a reduction in energy spread. The experimental results demonstrate that the projected FWHM energy spread of the beam can be reduced from 1.2% to 0.9% with a 12 mm long plasma dechirper, which are in good agreement with full three-dimensional particle-in-cell (PIC) simulations. Theoretical analyses and simulations indicate that by optimizing the plasma density and length, the plasma dechirper can also be used to completely remove the characteristic energy chirp of the ultra-short high-current bunch generated from plasma based accelerator, such that its energy spread can be reduced from one percent level to 0.1 percent level [1]. Application of such a simple and effective method can significantly improve the beam quality and provide the path to realize the future compact free electron lasers and colliders driven by plasma based accelerators.
[1] Y. P. Wu, X. L. Xu, et al., "A plasma dechirper for electron and positron beams in plasma-based accelerators", to be submitted to Scientific Reports |
||
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
TUPH07 |
Damping of Hosing Instability for Plasma-wakefield Acceleration in Uniform Plasma | |
|
||
| Current models predict the hosing instability to crucially limit the applicability of plasma-wakefield accelerators, especially for long driver cases. However, present analytical model is only suitable when beam size and hosing amplitude is much less than plasma blow-out radius. By developing a physically simple model which incorporates the single particle betatron motion and particle loss due to large betatron amplitude, this work demonstrates that the asymmetric particle loss due to the phase mismatch between beam hose and plasma respondency can damp hosing amplitude in magnitudes with negligible beam loss. We find excellent agreement between our model and 3D particle-in-cell simulations. Besides, for wide driver, we achieve stable propagation when transformer ration is about 5, which is almost impossible based on the previous understanding. | ||
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |