Abstract
Laser-generated plasmas were obtained in high vacuum by irradiating micrometric thin films (Au, Au/Mylar, Mylar) with the Asterix laser at the PALS Research Infrastructure in Prague. Irradiations at the fundamental wavelength, 300 ps pulse duration, at intensities up to about 1016W/cm2, enabled ions to be accelerated in forward direction with kinetic energies of the order of 2 MeV/charge state. Protons above 2 MeV were obtained in the direction orthogonal to the target surface in selffocusing conditions. Gold ions up to about 120 MeV and 60+ charge state were detected. Ion collectors and semiconductor SiC detectors were employed in time-of-flight arrangement in order to measure the ion velocities as a function of the angle around the normal direction to the target surface. A Thomson parabola spectrometer (TPS) with a multi-channel-plate detector was used to separate the different ion contributions to the charge emission in single laser shots, and to get information on the ion charge states, energy and proton acceleration. TPS experimental spectra were compared with accurate TOSCA simulations of TPS parabolas.
Highlights
Ion acceleration driven by laser-generated plasma is a major topic in various scientific fields, from ion sources to ion implantation, nuclear physics and biomedicine.In investigations of the macroscopic and microscopic effects occurringwhen a laser interacts with matter, one of the most important parameterd is the product Iλ2, where I is the laser intensity and λ is the laser wavelength
In the case of low power densities, the plasma in a high vacuum chamber expands along the normal direction to the irradiated target surface with a non-relativistic velocity, and the energy of the ion beam produced is of the order of 200 eV per charge state [9]
For Au, the maximum charge state is of the order of 70+, the maximum kinetic energy is of about 150 MeV, as seen from the Thomson parabola spectrometer (TPS) spectra
Summary
Ion acceleration driven by laser-generated plasma is a major topic in various scientific fields, from ion sources to ion implantation, nuclear physics and biomedicine.In investigations of the macroscopic and microscopic effects occurringwhen a laser interacts with matter, one of the most important parameterd is the product Iλ2, where I is the laser intensity and λ is the laser wavelength. The formation of laser plasma and its dynamics are different in cases of low or high laser power densities. In the case of low power densities, the plasma in a high vacuum chamber expands along the normal direction to the irradiated target surface with a non-relativistic velocity, and the energy of the ion beam produced is of the order of 200 eV per charge state [9]. In the case of high densities, the ion beam expands with a relativistic velocity, the typical ion energy values being about 2 MeV per charge state [1]. The investigated ion beam must be characterized in terms of the maximum ion energy, charge states, energy distribution, etc., as well as shotto-shot reproducibility
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