Theoretical Investigation Of Propagation Of Ultrashort Pulsed Beam And "X-ray Interferometry" In Diagnostics Of The Electron Density Of Laser Produced Plasma

In the paper, the propagation of the light, especially the propagation of the ultra-short pulsed beam was investigated in theory. The paper analyzed the vector analysis of propagation of the beam and ultrashort pulsed beam, and the paraxial approximation and nonparaxial correction of propagation of the ultrashort pulsed beam, et al. in free space. At the same time, the paper give out the investigation of X-ray interferometry in diagnostics of the electron density of laser produced plasma, and derived a modified term for WKBJ solutions. At last, we proved these by numerical simulation. They were applied in inertial confinement fusion program (ICF) , and experiments of the X-ray et al. The paper is composed of 4 chapters, among which are, Chapter 1 is a survey, Chapter 2,3,4 are the introductions of our own work.Chapter 1: The development and applied significance of the ultrashort pulsed beam and X-ray interferometry in diagnostics of the electron density of laser produced plasma are introduced;Chapter 2: By making use of Maxwell equations, the relations between the transverse field components and longitudinal component were derived in free space. By using elliptical polarized generalized paraxial beams, all components of vector field and Poynting vector were derived and analyzed, then the magnitude among them were compared. At the same time, the relations between energy density of field and the internal energy density in academician X.M. Deng's the hydrodynamics model optics(HMO) were presented. At last, we obtain several simple example about vector field.Charpter 3: This charpter investigated the propagation of one-cycle or few-cycle ultrashort pulsed beam in free space. Firstly, In the paper a family of integral solution representing ultrashort pulsed beam propagating in free space have been studied by using the co-moving frame coordinates and the Fourier transformation for time variable in terms of well-known paraxial approximation. And the pulsed Gaussian-like beam solution can be obtained as a especial solution of the integral solution, where including the pulsed Gaussian beam. Secondly, several special pulsed Gaussian beam were investigated. It is found that the Slowly-varying envelope approximation(SVEA) is invalid. SVEA will cause the spatial singularity for pulsed beam solution, and it is inconsistent with physical significance. But the complex analytical signal(CAS) theory can erase this spatial sigu-larity. In this section, Gauss, Hyperbolic and Lorentz pulsed Gaussian beam have been derived and compared SVEA and CAS solution by numerical simulation. In section 3, byusing Fourier transform technique and applying the paraxial approximation in frequency domain, we derive an integral solution for the transverse and longitudinal components of the light field propagating in free space. In particular, based on the complex analytical signal theory, the solutions for the components of a pulsed Gaussian-like beam in rectangular symmetry are derived and compared with those derived from slowly-varying-envelop-approximations (SVEA). The corresponding numerical investigations are carried out and show that for the pulses as short as sub-cycle, SVEA will cause the spatial singularity for both transverse and longitudinal components of the light field. In section 4, by making use of the Fourier transformation for spatial variables and starting from the nonparaxial propagating equation of ultrashort pulsed beam in temporal frequency domain, the nonparaxial solution basing on the paraxial propagating solution was derived, which come to exact solution by iterative of the paraxial integral solution. In section 5, the progress of the study on long-range propagation of ultrashort and ultrastrong laser pulses is outlined and the corresponding models are introduced, in which the dynamical spatial replenishment model is emphasized, the coupling equation originated from it and the corresponding numerial results are given. The validity of the models for different cases are analyzed.Charpter 4: Firstly, from Maxw...