Two-component structure in the angular emission of a laser-produced Ta plasma

  • The particle flux produced by an obliquely incident Nd Q-switched pulse (20 ns) on a Ta target has been analysed with regard to its angular distribution resolved for both its neutral and ion components. The laser intensity has been varied in the range between about 10^10 - 10^11 W cm-2, which is appropriate for many low-irradiance applications. It is observed that, at all emission angles and for the whole range of laser intensities, the number of neutral species clearly dominates the composition of the particles. At 1.3 x 10^10 W cm-2 the total number of emitted particles is 4 x 10^14, scaling as E_L^¾ with the laser energy. While for relatively low laser energies the angular distribution shows the usual smooth cos-behaviour, an additional strong directive emission cone, superimposed upon the cos-distribution, develops if the laser energy is enhanced. Both the strength and the width strongly depend on the laser intensity. While at lower intensities a fit by a cos^n function with n ~ 10 seems appropriate, n increases to 26 at an intensity of 10^11 W cm-2 . It can be assumed that secondary energy transfer processes that are not yet fully understood are responsible for this anomalous emission.

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Metadaten
Author:Andrea Thum, Axel Rupp, Klaus Rohr
URN (permanent link):urn:nbn:de:hbz:386-kluedo-15120
Document Type:Working Paper
Language of publication:English
Year of Completion:1994
Year of Publication:1994
Publishing Institute:Technische Universität Kaiserslautern
Contributing Corporation:Deutsche Forschungsgemeinschaft
Tag:Plasmaexpansion
Angular distribution; Laser-produced plasma; Neodymium lasers; Plasma expansion; Tantalum
GND-Keyword:Festkörper ; Güteschaltung ; Lasererzeugtes Plasma ; Neodym-YAG-Laser ; Tantal ; Winkelverteilung
Source:J. Phys. D: Appl. Phys., Vol. 27(1994), S.1791
Faculties / Organisational entities:Fachbereich Physik
DDC-Cassification:530 Physik

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