本計畫的主要目的在於利用解析理論與數值模擬來研究雷射電漿交互作用之非線性動力行為以及其應用研究，此研究包括三個主要研究子題：1. 次兆瓦雷射與高密度電漿作用之研究：將次兆瓦尖峰功率的雷射脈衝引入高密度的氣體靶材中，可以產生飛秒時寬且百萬電子伏特能量的電子束，這個機制使得微型雷射尾流加速器得以實現。此加速機制不僅可以降低實驗上雷射操作的複雜度，而且能夠提高雷射輸出的重覆率，產生高重覆率輸出的高能量電子束。透過模擬不同的雷射參數，以了解其加速限制，並提高使用更高重覆率的雷射應用至此機制上的可能。透過設計兩階段的氣囊或建立高原子序的氣體游離模型，加入模擬系統，以提高加速效益。2. 強場雷射產生高能質子束之研究：強場雷射與薄靶材作用，能夠產生高能質子束。而使用越薄的靶材，其對雷射強度的需求就越低。然而雷射與超薄靶材(<10奈米)的作用機制轉換細節尚未完全被釐清。此外，由於產生強場雷射，會伴隨著預脈衝的生成，其會降低質子加速效果。我們預計發展模擬程式，來探討強場雷射與超薄靶材作用產生高能質子束之物理機制，以及預脈衝對此機制的影響。3.湯姆森散射之研究: 透過雷射與電漿作用產生集體的散射波，可以解析非熱平衡且非線性的電漿狀態。量測高密度電漿的湯姆森散射訊號，必須透過壓縮雷射時寬去克服背景輻射的干擾，因此會加熱電漿改變其狀態。我們將建立理論與模擬模型，來分析在電漿中的電子加熱效應對湯姆森散射的影響。 ;The main purpose of the project is to apply the theoretical analysis and numerical simulation on the study of the dynamical behaviors of interactions between the intense electromagnetic wave and plasma in the relativistic regime as well as their applications. Three major research topics include:1. The study of the interaction between the sub-terawatt laser pulse and dense plasma: The femtosecond, MeV electrons can be generated by introducing sub-terawatt laser pulse into highly dense plasma, which benefits to develop a compact laser wakefield accelerator. This scheme can help decrease the operation complexity of laser systems and enhances the repetition rate of laser operation for the generation of high repetition rate electron pulse train. To figure out the acceleration limitation, a series of simulation will be conducted for parametric studies, which provides in-depth understanding for the development of electron accelerators operated at a higher repetition rate. The acceleration efficiency can be improved by designing the two-stage gas cell or mixing hydrogen gas with some high Z gas.2. The study of plasma-based proton/ion acceleration: The energetic protons can be generated by the interaction between intense laser with a thin target. The requirement of laser intensity is reduced when the target is extremely thin. However, the transition of dominant regimes has not been studied yet. Besides, the pre-pulse will affect the efficiency of ion acceleration. In this topic, the simulation model will be developed to investigate the plasma-based proton/ion acceleration and the effect of the pre-pulse.3. The study of Thomson scattering: The state of non-equilibrium (non-Maxwellian) and a non-linear plasma can be measured by collective Thomson scattering. In the measurement of a high-density plasma, the probe laser is compressed to overcome the strong background emission on the electron features. In this way, the plasma will be heated. The study will be conducted to investigate the electron heating effect in the equilibrium plasma by theoretical analysis and numerical simulation.
