C.-T. Hsieh, C.-M. Huang, C.-L. Chang, Y.-C. Ho, Y.-S. Chen, J.-Y. Lin, J. Wang, and S.-Y. Chen
Physical Review Letters 96, 095001 (2006)
A tomographic diagnosis method was developed to systematically resolve the injection and acceleration processes of a monoenergetic electron beam in a laser wakefield accelerator. It was found that all the monoenergetic electrons are injected at the same location in the plasma column and accelerated from 5 MeV to 55 MeV energy in 200-μm distance. This is a direct measurement of the real acceleration gradient in a laser wakefield accelerator, and the experimental data are consistent with the model of transverse wave-breaking and beam loading for monoenergetic electron injection.
Gin-yih Tsaur and Jyhpyng Wang
Physical Review Letters 80, 3682 (1998)
In the interaction picture, population transfer among coupled degrees of freedom is greatly enhanced by resonances. We show that statistically the number of resonances increases rapidly with degrees of freedom, changing the characteristic of population transfer from being bounded to diffusive. From the diffusion rate we derive simple expressions for the time scales of energy relaxation and equipartition. These expressions are supported by a wide range of experimental data. The analysis elucidates quantitatively the dependence of equipartition on resonances.
Institute of Atomic and Molecular Sciences Academia Sinica
