Influence of Gas Type on the Laser Produced Graphite Plasma

Plasma graphite creation by a pulsed Nd: YAG laser with a wavelength of 1064nm to a target in vacuum in two cases (Argon, Air) with varied gas pressures and the resulting spectrum was diagnosed using optical emission spectroscopy for the wavelength range 320-740nm electron temperature Te and electron density ne Debye lengthλD , and plasma frequency f p were calculated. The results showed that increasing the pulse laser energy causes all plasma parameters of both gases under study to increase, as well as a rise in the emission line intensity. The ionization energy of target atoms determines the presence of an element’s atomic and ionic emission lines in the emission spectrum, increase in pressure decreases the electron temperature, and Debye length, also plasma frequency and electron density increase, as it has been proven that the type of gas does not affect the properties of plasma.

Laser Shock Induced Deformation of Copper Foil on Diverse Molds and the Cross-Sectional Microstructure Changes

The microscale structures prepared on copper foil by laser shock deformation was introduced in the paper. The various sizes of hexagonal structures were successfully fabricated on copper foil with different molds. The influence of laser energy on the deformation depth of a hexagonal structure was studied using experiments. The morphology of the hexagonal structures on copper foil was observed by a three-dimensional profilometer, and mechanical property were characterized by a nanoindenter. A finite element model was established in order to describe the copper foil forming mechanism on mold and calculate the residual stress distribution. The microstructures and cross-section deformation of copper foil on different molds were also observed. The results indicated that the depth of hexagonal structures on 50# mold was higher than that of the structures on 100# mold and 230# mold, and the depth of hexagonal structures increased with the increasing of pulse laser energy. The copper foil above the mold hexagon side was bent and thinned after laser shock, and the grains of copper foil were also refining. The mechanical properties of copper foil were improved after laser shock was performed on the mold.

Effect of Target properties on the Plasma Characteristics that produced by Laser at Atmospheric Pressure

In this paper, Al and Cu Plasmas that produced by pulsed Nd:YAG laser with fundamental wave length with a pulse duration of 6 nS focused onto Al and Cu targets in atmospheric air are investigated spectroscopically. The influence of pulse laser energy on the some Al and Cu plasmas characteristics was diagnosed by using optical emission spectroscopy for the wavelength range 320-740 nm. The results observed that the increase of pulse laser energy causes to increase all plasma characteristics of both plasmas under study and shown increasing of the emission line intensity. The appearance of the atomic and ionic emission lines of an element in the emission spectrum depends on the ionization energy of target atoms. The plasma characteristics are subjected to the ionization energy of the target element and laser energy.