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Abstract
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In this paper, we use the conventional quantum hydrodynamics (QHD) model in combination with
th e Sagdeev ps eud opot enti al met hod t o expl ore t he ef fect s of Thomas -Fer mi non unif or m elect ron
distribution, Coulomb interactions, electron exchange, and ion correlation on the large-amplitude
nonlinear soliton dynamics in Fermi-Dirac plasmas. It is found that in the presence of strong
in ter acti ons , s ig nifi cant di ff er ences in nonl inear w ave dynamics of Fer mi- Dir ac plas mas in t he tw o
distinct regimes of nonrelativistic and relativistic degeneracies exist. Furthermore, it is remarked that
first-order corrections due to such interactions (which are proportional to the fine-structure constant)
ar e mo re s igni ficant on s oli ton char acter is tics ( par ti cul arl y t he amp li tud e) i n th e nonr elat ivi sti c
plasma degeneracy regime rather than the relativistic one. In the relativistic degeneracy regime,
however, these effects become less important and the electron quantum-tunneling and Pauli-exclusion
dominate the nonlinear wave dynamics. Hence, application of non-interacting Fermi-Dirac QHD
model t o s tudy t he nonl inear w ave dynamics in quant um p las mas , s uch as i n compact s tars is m os t
appropriate for the relativistic degeneracy regime rather than nonrelativistic one.
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