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A spectroscopic and diagnostic study of laser plasma generation and evolution under multi-variable target conditioning
Yeates, Patrick
The spectroscopic and electrostatic properties of laser generated plasmas under the influence of different target configurations have been investigated Three main diagnostic techniques have been employed Firstly, time and space resolved EUV(7-45nm) emission spectroscopy was used for timescales during and up to 35nsec after the laser pulse Secondly, space and time resolved visible (273-620nm) emission spectroscopy and fast frame visible imaging, was used for timescales during and up to 600nsec after the laser pulse Finally, ion and electron probes, sampled the temporal range from 800nsec onwards after the laser pulse. These three techniques, distinct in the space-time envelope in which they are applicable, divided the work into three regimes of the plasma lifetime under study, these were termed, ‘near field’, ‘intermediate field’ and finally, ‘far field’. For EUV(near field) studies, laser plasma generation and evolution within rectangular cavities was studied and compared to plasma undergoing free expansion from a flat target Substantial enhancement of intensities of the lines studied was demonstrated, while extended lifetimes of contained EUV plasma was observed Space and time resolved line widths, ionization (line ratio) and electron (Boltzmann) temperatures were calculated to characterize plasma behavior. For visible (intermediate field) studies, laser plasma generation and evolution within rectangular cavities, capillaries, and between vertical parallel plates and flat targets was undertaken Space and time resolved electron densities, ionization temperatures (line ratio) and electron temperatures (lme-to-continuum) were calculated to characterize plasma behavior Gated ICCD images were used to study plasma dynamics with each of the target configurations studied Large increases in plasma electron and ionization temperature, electron density, and forward expansion velocities were observed, for the three targets studied when compared to flat targets Enhanced plume ‘splitting’, was also demonstrated for confined plasma. For probe (far field) studies, arrays of ion and electron probes were used to study plume dynamics from various target configurations Ion and electron densities, electron temperature and velocities were calculated, and plume collimatton and superior time of flight velocities were observed for plasma generated within a confining target, when compared to plasma plumes from flat targets.
Keyword(s): Plasmas; Plasma processing; Laser generated plasmas
Publication Date:
2004
Type: Other
Peer-Reviewed: Unknown
Language(s): English
Contributor(s): Kennedy, Eugene T.
Institution: Dublin City University
Citation(s): Yeates, Patrick (2004) A spectroscopic and diagnostic study of laser plasma generation and evolution under multi-variable target conditioning. PhD thesis, Dublin City University.
Publisher(s): Dublin City University. School of Physical Sciences
File Format(s): application/pdf
Related Link(s): http://doras.dcu.ie/19890/1/Patrick_Yeates.pdf
First Indexed: 2014-04-01 05:42:52 Last Updated: 2019-02-09 06:25:53