http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Chalut, Kevin Duke University 2005 해외박사(DDOD)
The maximum lasing power achievable in a storage ring FEL is limited by the induced energy spread of the electron beam participating in the lasing process. In order to facilitate high peak power in the optical cavity at the Duke/OK-4 storage ring FEL, we have used giant pulses, which are obtained by using gain modulation. The use of giant pulses has allowed the expansion of the operational range of the Duke FEL into the vacuum ultraviolet region via the production of harmonics of the fundamental FEL wavelength. Numerical simulations of the giant pulse process performed by the #uvfel code have predicted a phase-space refreshing process whereby the synchrotron motion of the electrons moves heated electrons away from the interaction region and brings fresh electrons to it. Experimental verification of this process is necessary in order to enrich our knowledge of the physics at the Duke SRFEL. The giant pulse process, and particularly phase-space refreshment, occurs on a very: fast time scale compared to one-half of a synchrotron period. For phase-space tomography, previously existing methods have traditionally needed close to one-half of a synchrotron period's worth of projections in order to perform an accurate reconstruction of the phase-space density of a particle beam. Therefore, it was necessary to create a new method of phase-space tomography that would meet the needs brought about by the giant pulse process. The method we created for this purpose is called SVD-Based Tomography. A dual-sweep streak camera provides a set of equidistant linear projections of the electron beam, which we use for the purposes of phase-space reconstruction using SVD-Based Tomography. SVD-Based Tomography provides excellent reconstructions of the phase-space density of the electron beam during the giant pulse process using a very limited number of projections (as few as two, which is the minimum number of projections required for non-degeneracy). This algorithm is also promising for use in other medical and industrial applications, as it provides numerous upgrades over previously existing methods of tomographic reconstruction.