Optical Emission Studies Of A Plume Produced By Laser Ablation Of A Graphite Target In Air

Laser ablation can be applied to research a great many ofphysical phenomenon, and it also has many applications, suchas laser propulsion, plasma depositing thin film, producingclusters and nano-materials etc. At present the application oflaser ablation goes beyond its theory research, and many basicphysical process of laser ablation are still unclear. Due to thisreason it refrains the application of laser ablation, so it hasgreat value to research laser ablation process. There are many experimental research techniques toresearch laser ablation, the main techniques are opticalemission spectroscopy (OES), mass spectroscopy, fastphotography etc. Optical emission spectroscopy is the mostconvenient and powerful technique, and we used thistechnique in our experiment. We summarized differenttheoretical laser ablation process models in chapter II, andalso gave out the theoretical methods to work out the mostusual experimental parameters, such as the density andtemperature of electrons, molecular spectral temperature.In our experiment we use YAG laser (532nm wavelength,10 ns pulse width, 10Hz repetition) to ablate graphite target inorder to produce plasma, and we use spectral collectingequipments to collect spectrum of the laser induced plasma inorder to analyze the property of the plasma. Collecting thespectrum of different delay time, different distance to thetarget we can gain the number and velocity of the productionin the plasma, and we can also calculate the temperature of theplasma. From the spectral lines we can see intensive C2 andCN spectral band lines, but we can't find any spectralcharacteristic lines of other productions. From the change ofC2 and CN characteristic spectrum with time, space and laserintensity, we have gain the correspond values of the numberand velocity of C2 and CN to different time, space and laserintensity, and we also proved the reactivityC2*+N2=2CN*between plasma and air. Use Plank blackbodyradiation formula to simulate the continuous spectrum we havegot the plasma temperature and its evolution with time.