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2 Nukleonika

2 2012

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Proton emission from laser - generated plasmas at different intensities

Torrisi L., Cutroneo M., Cavallaro S., Giuffrida L., Margarone D.

Nukleonika

2012

Vol. 57, No. 2

237-240

Proton acceleration from laser-generated plasma is carried out at intensities ranging between 1010 and 1019 W/cm2, by using ns, ps and fs laser systems. The high energy density transferred from the pulsed laser beam into the solid target generates ionized species released in vacuum from the solid surface. Fast electrons followed by slower ions build up a double-layer and a consequent electric field, which is responsible for the ion acceleration mainly along the target-normal. Polymeric targets containing nanostructures (or metallic species) with high laser absorbing capacity, and metallic hydrates (or H-enriched metals), permit to increase the plasma temperature and density, thus to improve the proton beam energy and current. Thick targets and low laser intensities, operating in repetitive pulse, allows to generate high currents of low energy protons. On the other hand, through the use of thin targets and high laser intensities enabled the generation of high proton energies, above 1 MeV.

Post acceleration of ions emitted from laser and spark - generated plasmas

Torrisi L., Cavallaro S., Rosiński M., Nassisi V., Paperny V., Romanov I.

Nukleonika

2012

Vol. 57, No. 3

323-332

Pulsed lasers at intensities of the order of 1010 W/cm2 interacting with solid matter in vacuum, produce hot plasmas at high temperatures and densities. The charge state distributions of the plasma generate a high electric field, which induces high ion acceleration along the normal to the target surface. The high yield of the emitted ions can generate a near constant current by using repetitive pulses irradiating thick targets. In order to increase ion energy, a post-acceleration system can be employed by using acceleration voltages above 10 kV. Special ion extraction methods can be employed to generate the final ion beam, which is multi-ionic and multi-energetic, due to the presence of different ion species and of different charge states. In this article four different methods of post ion acceleration, employed at the INFN-LNS of Catania, at the IPPLM of Warsaw, at the INFN of Lecce and at the LPI of Moscow, are presented, discussed and compared. All methods are able to implant ions in different substrates at different depth and at different dose-rates.