Research Of The Spectrum Measurement Of Hard X-ray In The Interaction Of Femitosecond Laser With Solid Targets

Intensity field physics is the new region of Inertial Confinement Fusion (ICF), which has developed rapidly in the recent years. It brings forward the concept of "fast ignition" which has difference in the mode of ignition with the traditional inertial confinement fusion. Much of advance about fast ignition shows it is promising and economic to realize Inertial Confinement Fusion with the ultra short pulse laser. According to the suppose of the fast ignition, hot electrons produced by the interaction of the laser with plasma could effectually ignite the nuclear fuel. Thus, the research of the hot electron plays an important key in the intensity field physics. And its yield, temperature and transmission in targets were emphases to investigate. When hot electrons are transmitting in the targets and density plasma they collide with ions and produce bremstruhlung. Theoretically, hot electrons have the same distribution of energy with the bremstruhlung. And so, the measurement of the bremstruhlung spectrum could gain the temperature of hot electrons indirectly. With the intensity of laser increasing, the energy of hot electrons and bremstruhlung produced in the interaction of laser with plasma was higher and higher. The traditional detectors have not been fit for the requirement of experiments, such as the filter-fluorescer spectrometer. It became an important task to probe a new method diagnosing the energy spectrum of hard x-ray. Recent years, the thermoluminescence technology has been matured. And high-sensitivity,large-range and small-volume of the dosage filters caught sight of human being's eyes. The energy spectrum of 0.5~3 hard x-ray was firstly measured using several absorbed-filters and the thermoluminescence filters Li2B4O7 and CaSo4 in America. But the work was not still launched to diagnose the energy spectrum of hard x-ray using this technology at home. We firstly probed into this method to measure the energy spectrum of hard x-ray using LiF thermoluminescence detectors which has higher sensitivity than Li2B4O7 and CaSo4, and gained ideal results in experimentsThe thesis introduced the history of the traditional inertial confinement fusion and fast ignition, expatiated the ABC of the interaction of laser and plasma, reviewed the current condition of hard x-ray research, emphasized the dosimetry issue of a LiF Thermoluminescence detector in radiative fields and deduced the important formula of fundamental parameters of dosimetry. Based on these theories, the thesis expatiated the method measuring the energy spectrum of hard x-ray using the LiF Thermoluminescence detector, design of the hard x-ray spectrometer, and the relevant codes written in the advanced language Maple. The spectrum of standard radiant source 137Cs was measured using the hard x-ray spectrometer to validate the feasibility of the method; the experiment results were consistent with those given by other methods. Additionally, we measured the energy spectrum of the hard x-ray produced in the interaction of femitosecond laser with plasma and modeled the temperature of hot electrons. The results were in agreement with that given by the magnetic spectrometer of electron, and fit one and the same scaling law of hot electron's temperature. It demonstrated that the method was valid in experiments, which had particular virtues, and worthy of much probing.