| 摘要: | 高強度、具相干性之X光光源具有廣泛用，例如在分子動態成像、光譜學以及結構檢測，對了解化學、物理，醫學以及材料科學扮演重要腳色。一般產生高品質X光的方法有自由電子雷射以及同步輻射。在這當中，高品質的電子源扮演關鍵腳色。傳統電子源仰賴大型電子加速器，傳統加速器尺寸巨大原因是受限於容許的加速場，過高的加速場會導致材料放電。巨型加速器並不利於X光源在日常生活的應用。相反的，雷射驅動電漿加速因為沒有材料放電的問題，因此能容許高於傳統加速器數千倍的加速場，因此雷射驅動加速器有助於建造小尺寸、適合日常生活的X光源。我們計畫使用中央大學的一百兆瓦雷射在電漿中進行加速並產生具偏極化之X光光源，以及在極紫外光波段的自由電子雷射。我們預計使用側邊震波來控制X光之偏極化。一系列的技術包含電子相位重校正以及被動式電漿透鏡將會一併發展並整合以用來產生滿足自由電子雷射條件的高品質電子束。目前未止，尚未有雷射驅動之自由電子雷射被發表。 ;High brilliant and coherent X-ray sources are implemented in, for example, structure diagnostic, 4D molecular imagining and spectroscopy, and thus play important roles in the understanding of physics, chemistry, medicine and material science. Many methods have been used to generate high quality X-ray radiation, such as Free Electron Laser (FEL), synchrontron radiation. Energetic electron beams are a crucial element to produce high quality X-ray radiation. However, conventional accelerators are relative large due to the limitation of the accelerating gradient because of the material breakdown, which prevents the extent of application in our daily life. As a contrast, Laser WakeField Accelerator (LWFA) offers 1000 times higher gradient and is an ideal candidate of building a table-top electron source. We purpose to use 100TW laser system in National center university (NCU) to drive LWFA and generate polarized X-ray by betatron radiation, and free electron laser (FEL) in EUV range. Previous electron source are suffered from low quality, high energy fluctuation. Although some injection mechanism has be introduced to improve stability and quality of electron beam, the electron beam still suffers from large energy spread and large divergence angle. This research leverages and combines several advanced techniques, such as shock-front injection to achieve energy tunable electron source with low energy spread, reversed re-phasing to introduce negative chirp for electron pulse compression, and passive plasma lensing to reduce transvers emittance. We propose to use a side injection to arbitrarily tune the polarization and photon energy of betatron radiation. In the second part of this project, we use the optimized electron beam to create undulator radiation and demonstrate the FEL processing based on microbunching. FEL is highly important light source and have never been demonstrated by LWFA electron. |
