Research The Thermal Diffusion Of The Material Under The CO₂Laser Irradiation

In the study of the interaction between light and matter, heat transfering characteristics of the materialplay important roles. Material thermal diffusion rate is the ratio of the heat conductivity to specific heat.If the material thermal diffusion rate can be worked out, the material thermal conductivity can be gotten. Inthis paper, the research object is the sand mixed material. The principle of working out the soil of thermaldiffusion rate with the amplitude and phase method is expounded.A experiment is finished.In which,weuse the laser to illuminate the soil according to the heating effect of the laser, and then the data is obtained.The soil thermal diffusion rate can be solved from the data, and finally the ideal result of the experimentis obtained.The method of amplitude and phase is a classic method in research material thermal diffusion rate,first deduced the thermal conductivity equations of the soil temperature from micro-element method, andthen seek the solution of the heat conduction equations by Fourier series method, using this f solutiondeduced from the relationship of any depth temperature wave between amplitude and phase and the thermaldiffusion rate, using the method of harmonic analysis, analyses the relationship between the amplitude andphase and the depth of the different temperature, the last get the thermal diffusion rate K with differentdepth soil temperature, But this approach also has limitations, he required environment conditions stable,soil drying, etc.CO₂laser mainly lies in the infrared stage. because the big power and high calorific value. the coolingsystem is needed to work for cooling material in order to ensure stable output This paper designs a dualwater cycle cooling system, and a good cooling effect is achieved.This paper designs a experiment device in which carbon dioxide laser heat the material from the upperafter be steered and expanded.The material is put in a yuantong type of the container.In this device, thethermocouples are embedded in the material in different depth, and the soil temperatures in different depthare measured in a certain time intervals, and the experiment data is concluded, and then the soil thermaldiffusion rate is concluded by using the data, very close to the theoretical value. This experiment device canalso be used to measure the same type of other material's thermal diffusion rate, which can obtain test material properties and some of the relevant data.