由於?射技術的快速進步，高功?的超短脈衝?射正?斷的開?物?研究的新?域，這些?域通稱為強場物?。高功?超短脈衝?射的強大電磁場會讓電子的振盪速?接近光速，在這樣的?況下由於(v/c)×B這項磁?的作用，電子的運動變成極端的非線性，相對?效應也非常顯著，如何以?學方式有效描述電子在?射場中的相對?性非線性運動，對於強場物?是一個重要的課題。這方面的進展可以讓我們從一個統合的觀點?釐清?射電漿交互作用中的四個重要問題：(1) 電子的非線性振盪所產生的諧波?射(coherent harmonic generation)，(2) 電子的整?運動所產生的兆赫?射(terahertz radiation generation)，(3)垂直方向折射係? (refractive index)?同所造成的雙折射現象(relativistic birefringence)。(4) 聚焦的相對?性?射光束所產生的有質動?(ponderomotive force)。其中第(1)項的研究已於此計畫的第一?完成，第(2)項的研究於此計畫的第二?完成，第(3)項的研究於此計畫的第三?完成，第(4)項的研究則為此計畫(IV)的重點。這方面的研究對於?解?射與電漿的相對?性交互作用將有很大的幫助。 Since the development of broadband solid-state laser media, passive mode-locking techniques, and chirped-pulse amplification technique, high-power ultrashort-pulse laser technology has continuously generated exciting new frontiers of physics research. Under strong electromagnetic field, the quivering velocity of the electron approaches the speed of light. In this case, the magnetic force (v/c)?B makes the motion of the electron extremely nonlinear and the relativistic effects become significant. How to describe the electron motion under such high-intensity laser field in mathematical ways efficiently has been an important subject of research. By solving the relativistic equation of motion for the electron, one may clarify four important issues in laser-plasma interaction in a unified way: (1) coherent harmonic generation resulting from the nonlinear oscillation of the electrons, (2) terahertz radiation generated by the rectified motion of the electrons, (3) relativistic birefringence caused by the different refractive index in orthogonal directions, (4) ponderomotive force produced by a focused laser beam with relativistic intensity. Item (1) was studied in the first part of this project, item (2) was studied in the second part of this project, item (3) was studied in the third part of this project, and item (4) will be the focus of this final part. Research in this direction will be helpful for the understanding of relativistic laser-plasma interaction.
