MeV spectroscopy for ultra-intense laser-matter interactions

Date
2019
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University of Delaware
Abstract
Strong and ultrastrong field light-matter interactions encompass topics across atomic and molecular physics, high harmonic generation, fusion science, quantum control, and molecular imaging, which includes x-ray ionization, multi-photoionization, tunneling ionization, and classical over the barrier ionization. Current laser technology has enabled us to generate terawatts (1012 watts) or even petawatts (1015 watts) of optical power, while being focused down to spots as small as few micrometers, can generate peak intensity up to 1022 W/cm2. The traditional understanding of light-matter interactions breaks down at these extremely high intensities as the liberated photoelectrons possess speed highly close to that of light (v=c ≈ 1) therefore entering the relativistic regime. Furthermore, the dynamics of relativistic photoelectrons change significantly since the effect of the laser magnetic field is no longer negligible. Traditional laser-matter spectroscopy techniques fail to accurately analyze photoelectrons and ions from ultrahigh intensity studies with terawatt and petawatt laser systems. The work presented in this dissertation is to offer some insights and measurements of photoelectron yields and energies of the ionization of chloromethane (CH3Cl) and argon (Ar) in an ultrastrong laser field with intensities up to 1019 W/cm2 as well as present a magnetic deflection, photoelectron spectrometer for ultrahigh intensity (1019 W/cm2) laser interactions with atoms and molecules in the single atom/molecule limit, includes the spectrometer fabrication and calibration, noise background as well as example photoelectron spectra for argon and chloromethane over an energy range from 20 keV to 2 MeV.
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