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397 results on '"Nassisi, Vincenzo"'

154. Results of UV laser application on biological material

Author

ALIFANO, Pietro, NASSISI, Vincenzo, POMPA PP, CANDIDO A., Alifano, Pietro, Nassisi, Vincenzo, Pompa, Pp, and Candido, A.

Abstract

ALT’01 International Conference on Advanced Laser Technologies. D.C. Dumitras, M. Dinescu and V.I. Konov (Editors); A.M. Prokhorov (Chair).

Published
2001

158. ELECTRON EMISSION FROM A NIOBIUM PHOTOCATHODE

Author

NASSISI, Vincenzo, MARTINA, Luigi, A. Donateo, G. Raganato, M. Regler, Nassisi, Vincenzo, A., Donateo, Martina, Luigi, and G., Raganato

Subjects
Sorgenti di elettroni
Abstract

We report on the experimental results of a niobium photocathode illuminated by two different wavelength lasers operating at 308 and 222nm.The output current was recorded by a fast Rogowski coil while the beam angular distributions by small Faraday cups placed in front the beam. For λ=308nm the quantum efficiencies were 1.0×10-6 and 2.1×10-6 for p and s-polarisation, respectively. When the 222nm light was used they were 1.6×10-5 for p-polarisation and 5.3×10-5 for s-polarisation. In both cases the s-polarisation got efficiency higher. The maximum output current was 1.25A, τ=10ns; this value was obtained utilising the shortest wavelength laser, 4.9 mJ and 20 kV accelerating voltage. By the electron beam angular divergence, we determined the upper limit normalised emittance. The shortest value found of upper limit emittance was 7 [π mm mrad], achieved by the s- polarised radiation, at λ=308nm.

Published
2000

161. Electron emission from niobium photocathode

Author

NASSISI, Vincenzo, DONATEO, Antonio, MARTINA, Luigi, G. Raganato, Nassisi, Vincenzo, Donateo, Antonio, Martina, Luigi, and G., Raganato

Abstract

We report on the experimental results of a niobium photocathode illuminated by two different wavelength lasers operating at 308 and 222nm.The output current was recorded by a fast Rogowski coil while the beam angular distributions by small Faraday cups placed in front the beam. For λ=308nm the quantum efficiencies were 1.0×10-6 and 2.1×10-6 for p and s-polarisation, respectively. When the 222nm light was used they were 1.6×10-5 for p-polarisation and 5.3×10-5 for s-polarisation. In both cases the s-polarisation got efficiency higher. The maximum output current was 1.25A, τ=10ns; this value was obtained utilising the shortest wavelength laser, 4.9 mJ and 20 kV accelerating voltage. By the electron beam angular divergence, we determined the upper limit normalised emittance. The shortest value found of upper limit emittance was 7 [π mm mrad], achieved by the s- polarised radiation, at λ=308nm.

Published
2000

172. GENERATION OF SELF-PULSED MULTIPLY-CHARGED IONS BY AN XECL EXCIMER LASER

Author

LUCHES, A. PECORARO, PERRONE, Alessio, MARTINO, Maurizio, NASSISI, Vincenzo, Luches, Martino, Maurizio, Nassisi, Vincenzo, A., Pecoraro, and Perrone, Alessio

Abstract

Multiple charge heavy ion pulses were extracted from a plasma produced by an XeCl excimer laser beam at a relatively low flux ( approximately 30 MW/cm2) focused on Si, Ge, Mg and Zn targets. An output peak current of Si3+ ions of 375 mA was recorded at an acceleration voltage of 200 V only. The insertion of a variable capacitance between the target holder and the acceleration electrode allows a self-bunching of the ion beam. When a W target was used, a higher incident laser flux ( approximately 90 MW/cm2) was necessary in order to produce ions from it.

Published
1992

174. IR Light Coupling To Metal Surface

Author

S. JOVICEVIC, N. KONJEVIC, I. URSU, M. GANCIU PECTU, I. N. MIHAILESCU, V. STANCALIA, A. LUCHES, MARTINO, Maurizio, NASSISI, Vincenzo, S., Jovicevic, N., Konjevic, I., Ursu, M., GANCIU PECTU, I. N., Mihailescu, V., Stancalia, A., Luche, Martino, Maurizio, and Nassisi, Vincenzo

Abstract

Experimental results are reported, concerning the energy coupling of laser light to metal (copper) surfaces. It is shown that besides the ignition and the evolution of a surface plasma-of either erosion of optical breakdown type-the formation of surface chemical compounds and the condition of the sample surface play key roles in the determination of the interaction process, finally determining the energy coupling efficiency of laser radiation to metal samples.

Published
1991

178. Effects of 2 mass % Si admixture in a laser-produced Fe plasma

Author

Krása, Josef, primary, Láska, Leoš, additional, Rohlena, Karel, additional, Velyhan, Andriy, additional, Lorusso, Antonella, additional, Nassisi, Vincenzo, additional, Czarnecka, Agata, additional, Parys, Piotr, additional, Ryć, Leszek, additional, and Wolowski, Jerzy, additional

Published
2008
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181. Selective laser cleaning of chlorine on ancient coins

Author

Aiello, Domenico, primary, Buccolieri, Alessandro, additional, Buccolieri, Giovanni, additional, Castellano, Alfredo, additional, Di Giulio, Massimo, additional, Leo, Laura Sandra, additional, Lorusso, Antonella, additional, Nassisi, Gloria, additional, Nassisi, Vincenzo, additional, and Torrisi, Lorenzo, additional

Published
2006
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184. Sulphur selective ablation by UV laser

Author

Lorusso, Antonella, primary, Nassisi, Vincenzo, additional, Belloni, Fabio, additional, Buccolieri, Giovanni, additional, Caretto, Giuseppe, additional, and Castellano, Alfredo, additional

Published
2005
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194. Double Acceleration of Ions and Application in Biomaterials.

Author

Lorusso, Antonella, Siciliano, Maria Vittoria, Velardi, Luciano, and Nassisi, Vincenzo

Subjects
IONS, LASERS, PLASMA gases, BIOMEDICAL materials, ELECTRIC potential, CARBONIUM ions, POLYETHYLENE
Abstract

Ions of different elements were generated by laser-induced-plasma and accelerated by a two adjacent cavities. Therefore, the ions undergo a double acceleration imparting a maximum ion energy of 160 keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage. At 60 kV of total accelerating voltage, the maximum current peak was of 5.3 mA. The ion flux resulted of 3.4×1011 ions/cm2. The normalized emittance measured by pepper pot method at 60 kV was of 0.22 π mm mrad. By means of this machine, biomedical materials as UHMWPE were implanted with carbon and titanium ions. At a total ion flux of 2×1015 ions/cm2 the polyethylene surface increased its micro hardness of about 3-hold measured by the scratch test. Considering the ion emission cone dimension, we estimated a total extracted charge per pulse of 200 nC. [ABSTRACT FROM AUTHOR]

Published
2010
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