2026-09-20T03:07:15Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/871712022-01-13T07:54:01Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Abraham Bers and Juan C. Fernández.
Focia, Ronald J
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2014-05-23T19:03:39Z
2014-05-23T19:03:39Z
2001
2002
http://hdl.handle.net/1721.1/87171
50503736
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2002.
Includes bibliographical references (p. 247-254).
Control of parametric laser-plasma interactions (LPI) is essential to the success of inertial confinement fusion (ICF). Through a research collaboration with the Los Alamos National Laboratory (LANL), we have had the opportunity to participate in world-class laser-plasma experiments. The goal of these experiments was to gain a fundamental understanding of LPI by studying the interaction of a single laser hot spot, or speckle, with a preformed, quasi-homogeneous, long scale-length plasma. Recent single hot spot experiments resulted in a wealth of data and the first definitive observation of two LPIs. Namely, the Langmuir decay instability (LDI) cascade and stimulated scattering off of an acoustic-like electron mode below the usual electron plasma wave frequency. The LDI is the result of the electron plasma wave (EPW) generated by stimulated Raman scattering (SRS) growing to a sufficient amplitude such that it exceeds a threshold (proportional to the damping of the LDI daughter waves) and undergoes parametric decay into another counter-propagating EPW and a co-propagating ion acoustic wave (IAW). Subsequent EPW decays due to LDI are possible and collectively more than one EPW generated by LDI is called LDI cascade. The LDI cascade can play a role in the saturation of SRS since wave energy from the SRS EPW couples into secondary waves that are non-resonant with the SRS process. Stimulated scattering from an electrostatic wave at a frequency and phase velocity (co 0.4cpe, vl1.4ve) between that of an EPW and LAW was also observed.
(cont.) In this thesis, a Vlasov-Maxwell code is used to numerically predict the time evolution of the electron distribution function for the experimental parameters. The resultant distribution function is then modeled as a bi-Maxwellian (one background and one beaming) to show that it exhibits linear modes that include the observed electron acoustic wave. A quasimode analysis of laser scattering off of this linear mode is presented as one possible explanation of the experimental observation.
by Ronald J. Focia.
Ph.D.
243 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
Investigation and characterization of single hot spot laser-plasma interactions
Thesis
application/pdf
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="29397245-bb62-4558-b79d-46a37f4c9f36">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Investigation and characterization of single hot spot laser-plasma interactions</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2002</PublicationDate>
<Authors>
<Author>
<DisplayName>Focia, Ronald J</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Electrical Engineering and Computer Science.</Keyword>
<Abstract>Control of parametric laser-plasma interactions (LPI) is essential to the success of inertial confinement fusion (ICF). Through a research collaboration with the Los Alamos National Laboratory (LANL), we have had the opportunity to participate in world-class laser-plasma experiments. The goal of these experiments was to gain a fundamental understanding of LPI by studying the interaction of a single laser hot spot, or speckle, with a preformed, quasi-homogeneous, long scale-length plasma. Recent single hot spot experiments resulted in a wealth of data and the first definitive observation of two LPIs. Namely, the Langmuir decay instability (LDI) cascade and stimulated scattering off of an acoustic-like electron mode below the usual electron plasma wave frequency. The LDI is the result of the electron plasma wave (EPW) generated by stimulated Raman scattering (SRS) growing to a sufficient amplitude such that it exceeds a threshold (proportional to the damping of the LDI daughter waves) and undergoes parametric decay into another counter-propagating EPW and a co-propagating ion acoustic wave (IAW). Subsequent EPW decays due to LDI are possible and collectively more than one EPW generated by LDI is called LDI cascade. The LDI cascade can play a role in the saturation of SRS since wave energy from the SRS EPW couples into secondary waves that are non-resonant with the SRS process. Stimulated scattering from an electrostatic wave at a frequency and phase velocity (co 0.4cpe, vl1.4ve) between that of an EPW and LAW was also observed.</Abstract>
<Abstract>(cont.) In this thesis, a Vlasov-Maxwell code is used to numerically predict the time evolution of the electron distribution function for the experimental parameters. The resultant distribution function is then modeled as a bi-Maxwellian (one background and one beaming) to show that it exhibits linear modes that include the observed electron acoustic wave. A quasimode analysis of laser scattering off of this linear mode is presented as one possible explanation of the experimental observation.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>