Laser, optical and electrical diagnostics of colliding laser-produced plasmas

This thesis describes the development of and results from a new laboratory facility designed to investigate the properties and explore potential applications of colliding laser produced plasmas. When two plasmas collide there are two extreme scenarios that can play out – the plumes can either interpenetrate or stagnate depending on the ion-ion mean free path. During interpenetration, the plasmas stream through each other, the main interaction amounting to binary collisions. In the case of stagnation, rapid accumulation of plasma material at the collision front leads to the formation of a dense layer of material between the two plasmas. Interferometry of single laser produced plasmas created in background gaseous atmospheres expose the presence of a shock front at the plasma gas interface which rapidly expands outwards. Shadowgraphy is currently the most widely employed diagnostic technique to analyse such shock fronts and a comparison of both techniques reveals that interferometry can be used to diagnose the interaction of laser produced plasmas in gaseous environments in pressure regimes where other techniques such as shadowgraphy are not sensitive. Optical diagnostics such as laser interferometry, fast imaging (angularly resolved) and optical emission spectroscopy have been employed to probe colliding plasmas, revealing important factors in the formation of the stagnation layer. For example the studies have found that electrons stagnate before ions and similarly ions stagnate before neutral species.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Dublin City University

Year dc:date.issued

2010

Author dc:creator

• Hough, Pádraig

• Laser plasmas
• Physics

Language dc:language

en