Discussion on plasma shock waves generated by high-power pulsed laser
- PDF / 82,519 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 79 Downloads / 170 Views
S8.21.1
Discussion on plasma shock waves generated by high-power pulsed laser
ZhiHua Li
DuanMing Zhang Li Guan
Department of Physics, Huazhong University of Science and Technology, The national key lab of laser, Wuhan, 430074, China. ABSTRACT Sedov-Taylor theory is modified to describe plasma shock waves generated in a pulsed laser ablating process. Under the reasonable asymptotic behavior and boundary conditions, the propagating rules in the global free space (including close areas and mid-far areas) of pulsed-laser-induced shock waves are established for the first time. In particular, the temporal behavior of energy causing the difference of the propagation characteristics between the practical plasma shock wave and the ideal shock wave in point explosion model is discussed in detail. INTRODUCTION Pulsed Laser ablation(PLA) has become a dominant tool in many areas of technology, which can be used for welding, cutting, and drilling, and also for more exigent application[1,2], the interactions of a very dense laser beam with materials in PLA process provide an efficient mean to evaporate complex species. This is all the more true for high-power excimer laser where the sputtering process at short wavelength is more electronic than thermal, enabling the sputtering of a wide variety of materials, including dielectric, polymers and non-metals. For its ease of use and success in depositing materials of complex stoichiometry, PLA has gained a great deal of attention in the past few years. One advantage of PLA is the ability to fabricate films in high partial pressures of reactive gas, such as oxygen. It is
S8.21.2
crucial to maintain the proper oxygen content in the film during deposition of many oxides. Also, the presence of reactive gas can help bind volatile species to a substrate, preserving the film stoichiometry. Other advantages of PLA include its minimal vacuum requirements, lack of a need for specialized targets, and ability to deposit films of many different materials in situ for multilayer structures. Therefore, PLA is also widely used to search for materials that are used to synthesize more efficient thermoelectric devices for cooling and power generation applications[3,4]. Thermoelectric materials can directly convert heat into electric energy through thermoelectric power. Since this process is carried out only in materials, the power generating module of these materials has no movement, and power generation using these materials has high reliability. In addition, the thermoelectric device is environmentally friendly because it essentially produces no waste matter[5]. Therefore clarification of the physical mechanisms of PLA should be of great current interest just from the point of view of synthesizing more efficient thermoelectric materials. PLA involves many physical processes including the photoelectric effect; electron excitation, which induces the formation of electron-hole pairs; ionization; atom or cluster emission; phase explosion and so on[6]. Some progress has been made in investigation of t
Data Loading...
