Normaski Polarization Interferometry Diagnostics Of Plasma Electron Density And The Laser Into The Exploration Of The Road

One of the fascinating goals is to obtain pure fusion energy, for several decades a great number of scientists devote themselves into this area. The invention of laser light has opened a new field of investigation for plasma physicists. As an important way to achieve the aim, the inertial confinement fusion (ICF) has attracted great attention. Furthermore, ICF has important applications in many research fields, such as laboratory astrophysics, hydrodynamics, matter state equation, plasma physics, and so on.In recent years a large number of ultra-intensity lasers have been built to generate high energy particles for ICF. Among them, the fast ignitor (FI) of fusion raised great hopes by lowering the laser energy required to obtain the fuel burning and a thermonuclear gain. The FI principle relies upon the assumption that the oscillatory electrons can be converted into a high energy particle beam which will heat the dense core of a compressed pellet. The FI approach would ease dramatically the constraints on the implosion symmetry and improve the energy gain. However, there is a set of problem to solve before the FI will work. The laser pulse cannot reach the dense core of the target directly. The laser energy must be converted into fast particles first and then transported through the over-dense plasma region. The current solution implies that a long intense pre-pulse will first drill a channel in the coronal plasma. Once this channel formed, the following ultra-intense pulse will reach more easily the dense core. As a possible solution to FI problem, laser channel has received considerable interest.Focusing the final aim for the research of laser channel, we have invented a set of ways for diagnosis, the pre-plasma and laser channel have been studied.This work is organized in five sections. At first we review the laser development history and introduce briefly the concepts of ICF, FI and plasma diagnosis using laser probe.In section II v/e introduce the setup of the method for diagnosing the electron density in a plasma. The experimental results indicate that the signal intensity is not strong enough when using quadruple frequency laser probe. Therefore, we choose double frequency laser as the probe. The Normaski polarization interferometry has been designed. After solving some problem in the experiment, interferogram has been obtained.In section III, we introduce the experimental result by making use of the diagnosis system mentioned in section II. We have obtained the electron density distribution in the normal direction of different targets. The time evolution of electron density of Cu plasma has been obtained. Comparing with the theory simulation results, we find great difference between theoretical and experimental results. Furthermore, we have studied the laser channel, but we did not observe the channel structure in the experiment as our laser intensity was too low. Finally, we present some ideas for next experiment.In section IV, we introduce some research work of X-rays laser in these three years.In section V, a conclusion is presented.