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Laser-generated ns plasma pulses characterized using SiC Schottky diode
摘要： The nonequilibrium plasma generated by nanosecond laser pulse is characterized using a SiC detector connected in time-of-flight configuration to measure the radiations emitted from the plasma. Different metallic targets were irradiated by the pulsed laser at an intensity of 1010 W/cm2 and 200 mJ pulse energy. The SiC allows detecting ultraviolet radiations and soft X-rays, electrons, and ions. The obtained plasma has a temperature of the order of tens to hundreds eV depending on the atomic number of the irradiated target and ion accelerations of the order of 100 eV per charge state.
关键词： SiC-TOF,SiC detector,Laser-generated plasma,Photopeak
更新于2025-09-23 15:19:57
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IR ns pulsed laser irradiation of Polydimethylsiloxane in vacuum
摘要： Polydimethylsiloxane (PDMS) has been irradiated by a ns pulsed IR laser in vacuum and the radiation effects induced by the coherent radiation, above a threshold fluence, produce a non-equilibrium plasma and material ablation. The laser absorption can be enhanced using gold nanoparticles (AuNPs) embedded in the polymer. The laser-generated plasma has been characterized, whereas the ion emission from both the virgin PDMS and the PDMS t AuNPs sheets has been analysed both in mass and energy. Morphological investigations, optical spectroscopy and compositional analyses have been performed. The adopted laser treatment can be employed to modify the properties of PDMS with and without AuNPs inducing a local enrichment of microcrystalline silicon in both cases.
关键词： Laser ablation,PDMS,TOF,Laser-generated plasma,Polydimethylsiloxane
更新于2025-09-19 17:13:59
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Magnetically Induced Depolarization of Microwave Scattering from a Laser-Generated Plasma
摘要： The e?ects of a local external magnetic ?eld on microwave scattering from a laser-generated plasma are investigated by modeling and experiment, leading to the prediction and observation of magnetically induced depolarization of scattered microwaves. The sample volume is localized by the small laser-generated plasma and depolarization is shown to depend on both the magnitude and direction of the magnetic ?eld; this indicates the potential for stando? detection and measurement of vector magnetic ?elds in gases.
关键词： laser-generated plasma,microwave scattering,depolarization,standoff detection,magnetic field
更新于2025-09-12 10:27:22
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Protons and carbon ions acceleration in the target-normal-sheath-acceleration regime using low-contrast <i>fs</i> laser and metal-graphene targets
摘要： fs pulsed lasers at an intensity of the order of 1018 W/cm2, with a contrast of 10?5, were employed to irradiate thin foils to study the target-normal-sheath-acceleration (TNSA) regime. The forward ion acceleration was investigated using 1/11 μm thickness foils composed of a metallic sheet on which a thin reduced graphene oxide film with 10 nm thickness was deposited by single or both faces. The forward-accelerated ions were detected using SiC semiconductors connected in time-of-flight configuration. The use of intense and long pre-pulse generating the low contrast does not permit to accelerate protons above 1 MeV because it produces a pre-plasma destroying the foil, and the successive main laser pulse interacts with the expanding plasma and not with the overdense solid surface. Experimental results demonstrated that the maximum proton energies of about 700 keV and of 4.2 MeV carbon ions and higher were obtained under the condition of the optimal acceleration procedure. The measurements of ion energy and charge states confirm that the acceleration per charge state is measurable from the proton energy, confirming the Coulomb–Boltzmann-shifted theoretical model. However, heavy ions cannot be accelerated due to their mass and low velocity, which does not permit them to be subjected to the fast and high developed electric field driving the light-ion acceleration. The ion acceleration can be optimized based on the laser focal positioning and on the foil thickness, composition, and structure, as it will be presented and discussed.
关键词： TNSA,laser-generated plasma,SiC detector,ion acceleration in plasma
更新于2025-09-11 14:15:04