Laser driving flyer technology has been studied for many years and widely used in dynamic high-pressure physics and impact dynamics, rapid initiation of high explosives, simulation of space debris and micro-forming of metal foil. The coupling efficiency between the flyer kinetic energy and the laser energy could be improved by introducing a layer with stronger absorption at the 1064nm wavelength Nd:YAG laser, resulting in higher flyer velocity for a given laser energy. So a multilayer flyer (C/Al/Al2O3/Al) with Carbon absorption layer was designed and compared the flyer velocity with the flyer (Al/Al2O3/Al) without Carbon absorption layer. The experimental study was performed via the Photonic Doppler Velocimetry (PDV). The results show that the velocity of flyer with Carbon absorption layer rose with fluctuations as laser energy increasing, and was lower than that without Carbon layer at the same laser energy. That means the addition of Carbon absorption layer decreased the flyer coupling efficiency.
2, 4, 6-Trinitrotoluene (TNT) belongs to the group of aromatic nitro compounds which have extended use in industrial applications, in particular as explosives or additives to explosives. Understanding the initial step of laser induced decomposition of common explosives is important to the reliability and safety of laser initiators and firing systems. Lasers coupled with mass spectrometer find wide application in photochemical studies for identification of different ions formed due to photoexcitation/ionization of molecules by laser. In this paper, a pulsed Nd: YAG (15ns, 532nm) laser was used for ionizating the condensed TNT sample, and the ions produced in the ionization process were detected by a time of flight mass spectrometer (TOFMS). The influence of laser fluence and the delay time to the decomposition was also studied. According to the assignment of both positive and negative ions, possible laser induced dissociation pathways were proposed. The results may tell much about the initiation process and the chemical reaction that may occur in TNT when exposed to laser pulse.
Thin metal flyers were launched from an aluminum-coated glass support using nanosecond Nd: YAG laser pulses at 532 nm. The velocity of the flyers was measured as a function of incident energy using a time-of-flight method. Also, the effects of flying distance, flyer’s diameter, and its thickness on the velocity were researched. The results showed that the flyer’s velocity depends strongly on laser-pulse energy, its flying distance, and its thickness. This study demonstrates the important influence of these conditions on flyer’s velocity, which is essential for finding the optimal conditions for flyer to achieve the highest velocity.
A Q-switched Nd: YAG laser (with a wavelength of 532 nm and a pulse width of 15 ns) was used to ablate hexahydrol, 3,5-trinitro-l,3,5-triazine (RDX) in the air. The plasma emission spectra were recorded by an intensified charge-coupled device (ICCD) camera. The results showed that the plasma existed in the process of laser ablation of RDX. In the ultraviolet area, the main spectral lines were C I (187.46 nm and 223.01 nm), C II (323.1 nm) and N II (243.72 nm and 332.9 nm), while the dominating emission lines in the visible area were N II (393.9 nm and 454.7 nm), O II (490.75 nm) and O III (401.2 nm). Under experimental conditions, the intensities of the main peaks grew obviously with the increasing of the pulse delay, but laser energy didn’t have so much effect on the spectra. The ionization of the air almost did not influence plasma emission lines of RDX.
The porous silicon (PS) has gained increasing attentions in fields of nanoenergetic materials because of its especial chemical properties and mesoporous structured property (a large specific surface area: ～600m2/g). In this paper, the patterned (PS) films were realized by lithography technique on the polished surface of monocrystal silicon substrates, and the PS nanoenergetic chips (nECs) were created by impregnating the nanoscale pores of PS with ammonium perchlorate under the ultrasonic wave. The combustion of PS nECs was ignited by single pulse laser and the selfsustained burning was recoded by an optical high-speed camera at 20,000 frames per second. Its combustion performance was enhanced by ultrasonic wave in fabrications. Experiment results shown that the radial burning and channel burning were typical stages in combustions of PS nECs. In addition, the igniting energy of pulse laser beams affected the burning properties of PS nECs: the combustion of PS nECs could translate from propellant burning to deflagration with increases of laser beams energy ranged from 0.134mJ to 425mJ. In this work, the diameter of the irradiated spot on the PS nECs was about 700μm.. A strong plume of flame was emitted from the surface of PS nECs and this indicated that the potential for PS nECs to be applied as microigniters matrix chips and microthrusters matrix chips.