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MEASUREMENT OF ULTRAFAST DYNAMICS IN THE INTERACTION OF INTENSE LASER PULSES WITH GASES, ATOMIC CLUSTERS, AND PLASMAS

dc.contributor.advisorMilchberg, Howard Men_US
dc.contributor.authorKim, Ki-Yongen_US
dc.date.accessioned2004-05-31T19:46:17Z
dc.date.available2004-05-31T19:46:17Z
dc.date.issued2003-12-16en_US
dc.identifier.urihttp://hdl.handle.net/1903/93
dc.description.abstractWe have investigated the time resolved dynamics of intense, ultrashort pulse laser interactions with gases, nanometer-size clusters, and plasma waveguides. To probe the ultrafast dynamics in these interactions, we developed a new femtosecond optical diagnostic, single-shot supercontinuum spectral interferometry (SSSI), which measures ultra-rapid transients induced by an intense laser pulse in the complex index of refraction. The measurement of the transient refractive index in intense laser-heated materials provides a direct view of how the laser-produced perturbation evolves in time and space. Our SSSI diagnostic is capable of ~10 fs temporal resolution on a temporal window ~1.5 ps long, along with ~7 mm one-dimensional (1D) spatial resolution. SSSI was first applied to probe the ionization dynamics of helium gas under the irradiation of high intensity (~10^17 W/cm2) laser pulses. It revealed a characteristic stepwise transition process He - He+ - He2+, in agreement with the optical field ionization model. This measurement was used as a test case to demonstrate that finite laser-target interaction lengths can strongly affect the interpretation of all measurements involving extraction of transient phases. The time-resolved explosion dynamics of intense (~10^15 W/cm2) laser-heated clusters was also studied with SSSI and additional ultrafast optical diagnostics. Here, the ultrafast processes are ionization and rapid cluster plasma explosion. The measurement strongly supports our laser-cluster interaction scenario in which laser-heated clusters explode layer-by-layer, and the laser is strongly coupled at critical density. For the cluster sizes and laser intensities of this experiment, the measured several hundred-femtosecond evolution timescale of laser-heated clusters can be understood in terms of plasma hydrodynamics. A major implication of our understanding of microscopic cluster dynamics was the prediction and observation of self-focusing in clustered gases. Finally, using SSSI, we have explored the interaction of intense laser pulses with preformed plasma waveguides. This measurement revealed the presence of guided laser-induced distortions such as ionization, which can lead to degraded waveguide performance. To overcome this problem, a funnel-mouthed plasma waveguide was developed and diagnosed. In addition, a new plasma waveguide generation method has been demonstrated, which uses the unique features associated with the laser-cluster interaction self-focusing and strong absorption.en_US
dc.format.extent5968696 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.titleMEASUREMENT OF ULTRAFAST DYNAMICS IN THE INTERACTION OF INTENSE LASER PULSES WITH GASES, ATOMIC CLUSTERS, AND PLASMASen_US
dc.typeDissertationen_US
dc.relation.isAvailableAtDigital Repository at the University of Marylanden_US
dc.relation.isAvailableAtUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentPhysicsen_US
dc.subject.pqcontrolledPhysics, Opticsen_US
dc.subject.pqcontrolledPhysics, Fluid and Plasmaen_US
dc.subject.pqcontrolledPhysics, Atomicen_US


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