Study On Phenomenon And Regularity Of Rotation Of Carbon Nano Paper Driven By Pulsed Laser

Optical drive technology allows the object to gain acceleration by interacting light with matter(such as light pressure or photoacoustic effects)so that the object can be driven remotely.Generally,the light is driven to select a laser as a light source,and the driving material is selected to be a lightweight material having a porous structure.For example,a laser having a wavelength of 450 nm can drive the porous graphene material having a mass of 0.86 mg to move 40 cm against gravity.The carbon nano paper material is a new type of thermoacoustic material that has a lightweight and porous structure and can generate sound waves covering a frequency range of 100 Hz to 100 kHz.The theoretical calculations show that the thermal conductivity of single-walled carbon nanotubes in the axial direction is as high as 6000 Wm-1K-1 at room temperature,and the constant-pressure heat capacity of carbon nanotubes at room temperature is as low as 690 J/(kg·K).the air 1402 J/(kg·K).Because the carbon nanopaper is a new type of nanomaterial,there is currently no research report on the laser driven carbon nanopaper material.When the pulsed laser light is irradiated on the surface of the carbon nanopaper material,the carbon nanopaper absorbs light energy.Since the carbon nanotubes have a high thermal conductivity at constant pressure,the temperature of the carbon nanotubes in the porous structure of the carbon nano paper is rapid during the pulse duration.Raising and heating the air in the porous structure causes the temperature of the air to rise.With the end of the pulse,the temperature of the carbon nano paper rapidly decreases,and the temperature of the air in the porous structure also rapidly decreases.With the periodic pulsed laser,the temperature of the air It is also a cyclical change.This process can be considered as adiabatic,and periodic changes in the air temperature excite the periodic changes in air pressure,that is,sound waves.The propagation of sound waves in the air exerts a driving force on the carbon nano paper,so that under the irradiation of the pulsed laser light,the carbon nano paper with a very small mass is driven.Therefore,the laser power,pulse time,thickness of the carbon nano paper,and porosity,which can affect the thermoacoustic effect of the carbon nano paper,are also factors that influence the effect of the laser driven carbon nano paper material.The "porous medium heat transfer" module of COMSOL software was used to simulate the laser absorption and conduction of carbon nano paper materials.The effects of laser power,thickness and porosity of carbon nano paper on its heat transfer performance were studied.The higher the porosity,the better the heat transfer performance.When the carbon nano paper thickness is 150 um,the laser light energy absorption and conduction effect is the most significant.Compared to continuous lasers,pulsed lasers with the same average power,because of their high peak power,enable the temperature of carbon nano paper to rise even higher during the pulse time and rapidly cool down between the end of the pulse and the arrival of a pulse.The laser cooling effect increases the temperature and pressure variation of the porous structure of the carbon nano paper material in a pulsed laser step.YAG pulsed laser of 532 nm was used to drive carbon nanomaterials.The phenomenon and characteristics of YAG pulsed laser driving carbon nano paper rotation were studied.During the driving process,the surface of the carbon nano paper material was ablated by a pulsed laser and heard a distinct shock wave sound,and a small amount of black powder fell.Microscopy and SEM images observed the carbon nano-paper irradiated at the irradiated portion after irradiation with carbon nano paper.The structure was damaged and some of the material was lost.The measured light-driven rotation average angular velocity was 6 degrees per second.Combining the simulation results,this paper believes that the reason for the pulsed laser driving carbon nano paper material is that carbon nano paper absorbs and transmits pulse energy.The temperature and pressure of the air inside the porous structure oscillates periodically with the pulsed laser in the surrounding environment.Exciting the sound waves creates a driving force for lightweight carbon nano paper.The rapid rise in temperature and the impact of sound waves caused damage to the irradiated parts of carbon nano paper and loss of some substances.