Ultrashort pulse lasers focused in air result in plasma filaments that generate ultra-broadband secondary radiation that ranges from the megahertz to terahertz. The plasma currents responsible for the broadband radiation are the ponderomotive for the terahertz regime and the plasma wake surface wave (PWSW) for the gigahertz regime. Through experimental studies, I explore the optimization of microwave regime (1 - 67 GHz) of the spectrum. The experiments consider the effects of background gas and pressure in the filamentation region, pulse length of the laser, and wavelength of the laser on the plasma currents that produce the broadband radiated pulse. The results of the first experiment suggest that reduction of the electron-neutral collisions permits the growth of the PWSW and improve microwave amplitude. The second experiment demonstrates a growth in resulting microwave signal as a result of collisional processes driven by longer pulse durations. The final experiment demonstrates and order of magnitude increase in the microwave field amplitudes when the wavelength of a picosecond scale, terawatt class laser pulse is increased from 1.035 microns to 9.2 microns.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc2356215 |
| Date | 07 1900 |
| Creators | Thornton, Erin Ashley |
| Contributors | Rostovtsev, Yuri, Elle, Jennifer, Ordonez, Carlos, Weathers, Duncan |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | Text |
| Rights | Public, Thornton, Erin Ashley, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved. |
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