Investigation Of Properties And Expansion Dynamics Of Laser Plasma

The interaction between laser beam and materials has been the focus of both fundamental research and technology applications in related fields during the past forty years since T.H.Maiman produced the first ruby laser in 1960. Scientific research and technological applications based on pulsed laser ablation(PLA) has been developed. Especially in recent years, the rapid development of high energy ultrashort laser provides people with extreme experimental conditions such as unprecedented power density, field intensity and time precision etc which will lead to a lot of created study and breakthrough.HgCdTe is a kind of optimum material for infrared detector. It has been paid great attention by people since it came out because of its unique physical properties and great applied potential. It has brought about a great change in developing photoelectric detectors. At present, HgCdTe in the infrared techniques is as important as Si in microelectronics, so it is very significant to make a through study on HgCdTe. In addition, it is difficult to produce HgCdTe because of their complex preparation and high cost. In particular, the preparation of HgCdTe is regarded as the most defiant work in the world. Pulsed Laser Deposition technique is a method of thin film preparation which is produced during the study of laser induced plasma. So it is important to decide the character of plasma which will influence the property of film most. In this paper, the plasma characters of interaction between pulsed laser and HgCdTe were studied and valuable conclusion could help to improve PLD technology and the property of the film.An Optical Multi-channel Analyzer (OMAIII) was applied to detect the emission of HgCdTe plasma. The result showed that the plasma had been ignited within a very short time after the laser pulse reaching the surface and the plasma emission resulted in strong continuum. The continuum emission decreased as time went on and as the detector location was away from the target, and a lot of reasonable explanations were given for the temporal evolution characteristics of the emission spectra. Then the emission spectra from the plume produced by a pulsed laser ablation of an HgCdTe target at different ambient pressures were tudied, and we found that the emission spectra were largely influenced by the ambient gas. The velocity of the excited atoms and ions was obtained according to the time that the particles reached the observation position, and the dependence of the projected distance of the particles on the delay time were studied. Finally Monte-Carlo Srim 2003 simulation program was used to simulate the projected distance, the projected distance distribution and the energy loss distribution.In the present work, the theoretical analysis of the LSDW of laser ablation HgCdTe target and the plasma expansion was carried out on the basis of experiment results. We improved the previous expansion model by taking into account the energy loss of radiation and ionization. The scale laws of the ejected distance, velocity, pressure, and density of the plasma were obtained by using numerical solution at different pressures, the results were also consistent with experiment results. Finally some problems included in the established model were discussed.