A new model for studying the plasma plume expansion property during nanosecond pulsed laser deposition

Abstract

A physical model is proposed to study the laser-induced plasma dynamics expansion during irradiation of material by a high-intensity nanosecond pulsed laser beam. Based on a consideration of the plasma ionization effect and local conservations of mass, momentum and energy, combined with the assumption that plasma can be viewed as a compressible ideal fluid and a high temperature–high pressure ideal gas, we developed a new dynamics expansion mechanism for plasma produced by pulsed laser radiation. A set of new plasma expansion dynamics equations based on our model are first deduced. Then, taking the example of the carbon target, using the finite difference method, the plasma flow dynamics into a vacuum, such as plasma spacial number density distribution, plasma number density and velocity evolvement in radial and axial directions, are studied in detail. The results show that there are some main factors affecting the velocity distribution of the plasma, including the temperature of the plasma, the ionization fraction of the plasma and the dynamic source provided by the vaporized material. The velocity uz in the longitudinal direction is different from ur in the transverse direction because of huge initial eject velocity and evaporated dynamic source. The velocities of the plasma calculated by this model are found to be in better agreement with the experimental results derived from the work of Sanz et al (1985 Plasma Phys. Control. Fusion 27 329) compared with the conventional model.

Research on the mechanism of particle deposit effects and process optimization of nanosecond pulsed laser truing and dressing of materials

“…10,23 Therefore, in the Xand R-directions, the initial velocity of the plasma expansion is approximately equal to that of the mean free path molecular motion. Based on the above analysis and the results presented in the literature, 14 in the X-and R-directions, the initial expansions are both approximately 10 À6 m, while the initial velocities are approximately 970 m s À1 and 1.53 m s À1 , respectively, and the initial accelerations are approximately 958 Â 10 9 m s À2 and 479 Â 10 9 m s À2 , respectively. Fig.…”

“…The expressions for A and N λ are found in ref. 14 : (see Appendix A) where L X ( t ) and L R ( t ) are the edge space dimensions at the plasma expansion time t . a is the refractive index of the material, U is the excitation energy, τ is the pulse time.…”

Numerical simulation of laser-induced plasma in background gas considering multiple interaction processes

“…In the direction parallel to the target surface, the initial size of the plasma is the spot radius, while in the direction perpendicular to the target surface, the plasma is considered as a high-temperature and dense monatomic ideal gas, so its initial size is close to the mean free path of species motion [22]. After the laser is finished, the initial size of plasma can be obtained by simulating the action of laser pulse through kinetic method [23,24]. This method is based on the theory of fluid dynamics and combined with the self-similarity theory to obtain the relationship between plasma size and time.…”

Plasma Generation and Application in a Laser Ablation Pulsed Plasma Thruster

“…Afterwards, the hydrodynamic model had been widely applied to study various laser-solid interactions [25][26][27][28]. In order to calculate the laser energy loss caused by plasma absorption and shielding, the formation of plasma in the plume was also considered in several hydrodynamic models [22,[29][30][31][32]. Therefore, we establish a hydrodynamic model to investigate the ablation plasma expansion and ionization in the ceramic tube.…”