{"id":{"repo_id":"unr","oai_identifier":"oai:scholarwolf.unr.edu:11714/10532"},"canonical_url":"https://search.dev.ndltd.org/etd/unr/oai:scholarwolf.unr.edu:11714/10532","repository":{"repo_id":"unr","name":"University of Nevada - Reno","base_url":"https://scholarwolf.unr.edu/server/oai/request"},"display":{"title":"Characterization of short-pulse laser-produced fast electrons by 3D hybrid particle-in-cell modeling of angularly resolved bremsstrahlung","abstract":"The interaction of an intense short-pulse laser with a solid target efficiently generates energetic (fast) electrons above the energy of 1 Mega-electronvolt (MeV). Characterization of such high-energy electrons is critical for numerous applications, such as the generation of secondary particle sources, the creation of warm dense matter (WDM), advanced fusion concepts, and intense x-ray radiation for probing complex high areal density objects and inertial confinement fusion (ICF) fusion cores. However, determining laser-driven fast electron characteristics, specifically, electron energy distribution, divergence angle, and laser-to-electron conversion efficiency, has been challenging partly due to complex electron trajectories caused by electric sheath potential, known as electron recirculation. This thesis reports on developing a novel fast electron characterization technique by modeling angularly resolved bremsstrahlung radiations with a three-dimensional (3D) hybrid Particle-in-cell (PIC) code. An experiment using a 50-TW Leopard laser (15 J, 0.35 ps, 2×10^19 W/cm2) was carried out to measure bremsstrahlung radiations at two angular positions and escaped fast electrons along the laser axis for two types of targets: a 100-μm- thick Cu foil and a same Cu target with a CH backing (Cu-CH target). A 3D hybrid-PIC code, Large Scale Plasma (LSP), is extensively used in this work to simulate the electron transport within the solid target, including electron recirculation around the target, and the x-ray generation of absolute photon yields. The measurements were fitted with a series of simulations by varying all three electron parameters. Fitting results based on chi-squared analyses show good agreements for both target types when the electron slope temperature of 0.8 MeV, the divergence angle of 70 degrees, and the electron beam energy of 1.3 J are used. Furthermore, the effects of electron recirculation on bremsstrahlung generation and the enhancement of a short-pulse laser-produced x-ray intensity in various foil thicknesses are numerically studied. These results provide insight into designing and optimizing an x-ray source target for broadband x-ray radiography of a magnetically compressed aluminum rod at the Zebra pulsed power laboratory.","abstract_html":"The interaction of an intense short-pulse laser with a solid target efficiently generates energetic (fast) electrons above the energy of 1 Mega-electronvolt (MeV). Characterization of such high-energy electrons is critical for numerous applications, such as the generation of secondary particle sources, the creation of warm dense matter (WDM), advanced fusion concepts, and intense x-ray radiation for probing complex high areal density objects and inertial confinement fusion (ICF) fusion cores. However, determining laser-driven fast electron characteristics, specifically, electron energy distribution, divergence angle, and laser-to-electron conversion efficiency, has been challenging partly due to complex electron trajectories caused by electric sheath potential, known as electron recirculation. This thesis reports on developing a novel fast electron characterization technique by modeling angularly resolved bremsstrahlung radiations with a three-dimensional (3D) hybrid Particle-in-cell (PIC) code. An experiment using a 50-TW Leopard laser (15 J, 0.35 ps, 2×10^19 W/cm2) was carried out to measure bremsstrahlung radiations at two angular positions and escaped fast electrons along the laser axis for two types of targets: a 100-μm- thick Cu foil and a same Cu target with a CH backing (Cu-CH target). A 3D hybrid-PIC code, Large Scale Plasma (LSP), is extensively used in this work to simulate the electron transport within the solid target, including electron recirculation around the target, and the x-ray generation of absolute photon yields. The measurements were fitted with a series of simulations by varying all three electron parameters. Fitting results based on chi-squared analyses show good agreements for both target types when the electron slope temperature of 0.8 MeV, the divergence angle of 70 degrees, and the electron beam energy of 1.3 J are used. Furthermore, the effects of electron recirculation on bremsstrahlung generation and the enhancement of a short-pulse laser-produced x-ray intensity in various foil thicknesses are numerically studied. These results provide insight into designing and optimizing an x-ray source target for broadband x-ray radiography of a magnetically compressed aluminum rod at the Zebra pulsed power laboratory.","abstract_has_math":false,"creators":["Chen, Lei"],"institution":null,"degree_name":null,"degree_level":"Doctorate Degree","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Sawada, Hiroshi"],"committee_chairs":[],"committee_members":["Mancini, Roberto","Weinstein, Jonathan","White, Thomas","Barile, Christopher"],"year":2023,"date_issued":"2023","date_published":"2023","updated_at":"2026-07-27T21:47:14Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11714/10532","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Sawada, Hiroshi"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Mancini, Roberto","Weinstein, Jonathan","White, Thomas","Barile, Christopher"]},{"key":"dc:creator","label":"Author","values":["Chen, Lei"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2023-09-19T22:08:31Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2023-09-19T22:08:31Z"]},{"key":"dc:date.issued","label":"Date","values":["2023"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Doctorate Degree"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11714/10532"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The interaction of an intense short-pulse laser with a solid target efficiently generates energetic (fast) electrons above the energy of 1 Mega-electronvolt (MeV). Characterization of such high-energy electrons is critical for numerous applications, such as the generation of secondary particle sources, the creation of warm dense matter (WDM), advanced fusion concepts, and intense x-ray radiation for probing complex high areal density objects and inertial confinement fusion (ICF) fusion cores. However, determining laser-driven fast electron characteristics, specifically, electron energy distribution, divergence angle, and laser-to-electron conversion efficiency, has been challenging partly due to complex electron trajectories caused by electric sheath potential, known as electron recirculation. This thesis reports on developing a novel fast electron characterization technique by modeling angularly resolved bremsstrahlung radiations with a three-dimensional (3D) hybrid Particle-in-cell (PIC) code. An experiment using a 50-TW Leopard laser (15 J, 0.35 ps, 2×10^19 W/cm2) was carried out to measure bremsstrahlung radiations at two angular positions and escaped fast electrons along the laser axis for two types of targets: a 100-μm- thick Cu foil and a same Cu target with a CH backing (Cu-CH target). A 3D hybrid-PIC code, Large Scale Plasma (LSP), is extensively used in this work to simulate the electron transport within the solid target, including electron recirculation around the target, and the x-ray generation of absolute photon yields. The measurements were fitted with a series of simulations by varying all three electron parameters. Fitting results based on chi-squared analyses show good agreements for both target types when the electron slope temperature of 0.8 MeV, the divergence angle of 70 degrees, and the electron beam energy of 1.3 J are used. Furthermore, the effects of electron recirculation on bremsstrahlung generation and the enhancement of a short-pulse laser-produced x-ray intensity in various foil thicknesses are numerically studied. These results provide insight into designing and optimizing an x-ray source target for broadband x-ray radiography of a magnetically compressed aluminum rod at the Zebra pulsed power laboratory."]},{"key":"dc:format","label":"Dc Format","values":["PDF"]},{"key":"dc:title","label":"Title","values":["Characterization of short-pulse laser-produced fast electrons by 3D hybrid particle-in-cell modeling of angularly resolved bremsstrahlung"]}]}],"canonical_facts":{"dc:contributor.advisor":["Sawada, Hiroshi"],"dc:contributor.committeemember":["Mancini, Roberto","Weinstein, Jonathan","White, Thomas","Barile, Christopher"],"dc:creator":["Chen, Lei"],"dc:date.accessioned":["2023-09-19T22:08:31Z"],"dc:date.available":["2023-09-19T22:08:31Z"],"dc:date.issued":["2023"],"dc:description.abstract":["The interaction of an intense short-pulse laser with a solid target efficiently generates energetic (fast) electrons above the energy of 1 Mega-electronvolt (MeV). Characterization of such high-energy electrons is critical for numerous applications, such as the generation of secondary particle sources, the creation of warm dense matter (WDM), advanced fusion concepts, and intense x-ray radiation for probing complex high areal density objects and inertial confinement fusion (ICF) fusion cores. However, determining laser-driven fast electron characteristics, specifically, electron energy distribution, divergence angle, and laser-to-electron conversion efficiency, has been challenging partly due to complex electron trajectories caused by electric sheath potential, known as electron recirculation. This thesis reports on developing a novel fast electron characterization technique by modeling angularly resolved bremsstrahlung radiations with a three-dimensional (3D) hybrid Particle-in-cell (PIC) code. An experiment using a 50-TW Leopard laser (15 J, 0.35 ps, 2×10^19 W/cm2) was carried out to measure bremsstrahlung radiations at two angular positions and escaped fast electrons along the laser axis for two types of targets: a 100-μm- thick Cu foil and a same Cu target with a CH backing (Cu-CH target). A 3D hybrid-PIC code, Large Scale Plasma (LSP), is extensively used in this work to simulate the electron transport within the solid target, including electron recirculation around the target, and the x-ray generation of absolute photon yields. The measurements were fitted with a series of simulations by varying all three electron parameters. Fitting results based on chi-squared analyses show good agreements for both target types when the electron slope temperature of 0.8 MeV, the divergence angle of 70 degrees, and the electron beam energy of 1.3 J are used. Furthermore, the effects of electron recirculation on bremsstrahlung generation and the enhancement of a short-pulse laser-produced x-ray intensity in various foil thicknesses are numerically studied. These results provide insight into designing and optimizing an x-ray source target for broadband x-ray radiography of a magnetically compressed aluminum rod at the Zebra pulsed power laboratory."],"dc:format":["PDF"],"dc:identifier.uri":["http://hdl.handle.net/11714/10532"],"dc:title":["Characterization of short-pulse laser-produced fast electrons by 3D hybrid particle-in-cell modeling of angularly resolved bremsstrahlung"],"dc:type":["Dissertation"],"thesis:degree_level":["Doctorate Degree"]},"updated_at":"2026-07-27T21:47:14Z"}