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dc.contributor.advisorRocca, Jorge J.
dc.contributor.authorBerrill, Mark Allen
dc.contributor.committeememberMarconi, Mario C.
dc.contributor.committeememberMenoni, Carmen S.
dc.contributor.committeememberLee, Siu Au
dc.date.accessioned2007-01-03T04:41:35Z
dc.date.issued2010
dc.descriptionDepartment Head: Anthony A. Maciejewski.
dc.description2010 Summer.
dc.descriptionIncludes bibliographical references.
dc.description.abstractThis dissertation describes the development of computer models to simulate laser created plasmas used to generate soft x-ray lasers. These compact short wavelength lasers have substantial average powers and very high peak brightness, that make them of significant interest for many applications. A better understanding of the plasmas is necessary to advance the development of these lasers into more compact, efficient, and higher power sources of coherent soft x-ray light. The plasma phenomena involved are complex, and require a detailed computer model of the coupled magneto-hydrodynamic and atomic physics processes to simulate their behavior. The computer models developed as part of this work consist of hydrodynamic equations, coupled with an atomic model, radiation transport, and a ray propagation equation. The models solve the equations in a 1.5D or 2D approximation, and predict the spatio-temporal plasma variation of the parameter s, including the electron density and temperature, and the ion populations, which are then used to compute the population inversion and the resulting laser gain. A 3D post processor ray trace code was developed to simulate the amplification of stimulated emission along the plasma column length including saturation effects. This allows for the direct calculation of the soft x-ray laser output and its characteristics. Simulation results were compared with experiments conducted at Colorado State University. The general behavior of the plasma and the soft x-ray laser are well described by the model. A specific comparison of the model results with experimental measurements is presented for the case of a collisionally excited 13.2 nm wavelength Ni-like cadmium laser. The model predicts that an optical laser pulse of 1 J energy and 8 ps duration impinging at 23 degrees grazing incidence into a pre-created laser plasma can rapidly heat it to temperatures above 600 eV at a density of 2 x 1020 electrons/cm3. This results in a computed peak small signal gain coefficient of 150 cm-1 in the 4d 1S0 to 4p 1P1 transition of Ni-like Cd at 13.2 nm. The model indicates that the amplified beam reaches the gain-saturated regime after 2.5 mm of propagation in the plasma, in agreement with the experimental observation of saturated behavior for propagation lengths of 2.5-3.0 mm. The computed soft x-ray laser pulse width of 5-9 ps moderately exceeds the experimental value of 5 ps and is the result of a stronger saturation broadening in the simulation. The simulated laser output energy of the order of 1 μJ is also in agreement with experiments. Simulations of injection-seeded Ne-like Ti and Ni-like Ag amplifiers that show very good agreement with the experimental results are presented. A direct comparison of the pulsewidth and the near and far-field beam profiles is made. Finally, the results of a simulation of a plasma created by irradiation of solid targets with a 46.9 nm soft x-ray laser, in which single photon photoionization is the dominant energy absorption mechanism are presented. Low absorption (silicon, Z=14) and high absorption (chromium, Z=24) targets were heated by ~1 ns duration soft x-ray laser pulses. The experimental spectra agree with 1 ½ D simulations in showing that the Si plasmas are significantly colder and less ionized than the Cr plasma, confirming that in contrast to plasmas created by visible wavelength lasers the plasma properties are largely determined by the absorption coefficient of the target material.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierBerrill_colostate_0053A_10061.pdf
dc.identifierETDF20101000005ECEN
dc.identifier.urihttp://hdl.handle.net/10217/40280
dc.languageEnglish
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019 - CSU Theses and Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectEUV
dc.subjectsoft x-ray
dc.subjectplasma
dc.subjecthydrodynamic
dc.subject.lcshLaser plasmas -- Computer simulation
dc.subject.lcshLaser-plasma interactions -- Computer simulation
dc.subject.lcshX-ray lasers -- Computer simulation
dc.titleModeling of laser-created plasmas and soft x-ray lasers
dc.typeText
dcterms.embargo.expires2011-09-01
dcterms.rights.dplaThe copyright and related rights status of this item has not been evaluated (https://rightsstatements.org/vocab/CNE/1.0/). Please refer to the organization that has made the Item available for more information.
thesis.degree.disciplineElectrical and Computer Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)


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