Abstract
To study the plasma plume expansion dynamics of nanosecond laser ablating Al/PTFE, the Al/PTFE propellant was prepared by a molding sintering method and the rapid expansion process of the plasma plume was photographed using fast photography technology. The effects of the proportion of Al, laser energy and ambient pressure on plasma plume expansion dynamics are analyzed. The results show that the plume expansion process of laser ablating Al/PTFE plasma can be divided into three stages and this phenomenon has not been reported in the literature. The Al powder doped in PTFE will block part of the laser transmission into the propellant, thus reducing the laser absorption depth of the propellant. In the case of short pulse laser ablation, the reaction rate between Al and PTFE is optimal when the reductant is slightly higher than the oxidant. As the laser energy increases, the light intensity of the plasma becomes stronger, the plasma size becomes larger and the existence time of plasma becomes longer. In the first stage plume, the plume expands freely at the ambient pressure of 0.005 Pa and the plume expansion distance is linearly related to time, while the shock wave formed at the interface between the plume front and the ambient gas at the ambient pressure of 5 Pa and the expansion can be described by S-T theory.
Highlights
In order to improve propulsion performance and system simplicities of conventional electric and laser propulsion systems, the concept of laser-electromagnetic hybrid propulsion system was proposed by Horisawa et al [1,2,3,4,5]
The plasma plume evolution process of 26.5% Al at a background pressure 0.005 Pa and laser energy of 542.3 mJ is shown in Figure 5, where it can be seen that the laser ablation plasma plume is energy of 542.3 mJ is shown in Figure 5, where it can be seen that the laser ablation plasma plume is almost symmetrically distributed with respect to the normal direction of the propellant
This phenomenon is different from laser ablating pure Al [30,31] or PTFE [31] and it has not yet been reported in the literature, which is a new ablation phenomenon
Summary
In order to improve propulsion performance and system simplicities of conventional electric and laser propulsion systems, the concept of laser-electromagnetic hybrid propulsion system was proposed by Horisawa et al [1,2,3,4,5]. The possible reason is that laser pulse is too long,the making the ablation plumemaking shield reduce the propulsion performance. PTFEto is reduce expected reduce the laserdepth, penetration which the laser energy per unit volume and improve the ablation efficiency of the propellant. Can increase the laser energy per unit volume and improve the ablation efficiency of the propellant. The plasma evolution process of nanosecond pulse laser ablation of Al/PTFE. The plasma evolution process of nanosecond pulse laser ablation of Al/PTFE propellant under propellant under pressures different ambient pressures different laser energies wasby photographed the different ambient and different laserand energies was photographed the ultrahighbyspeed ultrahigh speed camera.evolution.
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