Engineering topics

Lei, Chang

Publications and source records attributed to Lei, Chang.

5 records

DOE OSTI2011

Numerical studies of the high power microwave breakdown in gas using the fluid model with a modified electron energy distribution function

A modified electron energy distribution function (EEDF) is introduced into the fluid model and its effects on the high power microwave (HPM) breakdown in air and argon are investigated. A proper numerical scheme for the finite-difference time-domain method is employed to solve the fluid model. Numerical simulations show that the HPM breakdown time in argon predicted by the fluid model with the modified EEDF agrees well with the results of Particle-in-cell-Monte Carlo collision simulations, while the Maxwellian EEDF results in faster HPM breakdown when the mean electron energy is less than 20 eV. We also confirm that the Maxwellian EEDF can be used in the fluid model for simulating the air breakdown at the low frequencies based on the reported experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2011

QCD Phase Diagram Using Dyson-Schwinger Equations

We describe briefly the Dyson-Schwinger equation approach of QCD and the study of the QCD phase diagram in this approach. The phase diagram in terms of the temperature and chemical potential, and that in the space of coupling strength and current-quark mass are given.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

T(r)opical Dyson-Schwinger Equations

We provide a glimpse of recent progress in hadron physics made using QCD's Dyson-Schwinger equations, reviewing: the notion of in-hadron condensates and a putative solution of a gross problem with the cosmological constant; the dynamical generation of quark anomalous chromo- and electro-magnetic moments, and their material impact upon the proton's electric/magnetic form factor ratio; a computation that simultaneously correlates the masses of meson and baryon ground- and excited-states; and a prediction for the x{yields}1 value of the ratio of neutron/proton distribution functions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Quark Spectral Function above T{sub c}

The maximum entropy method is used to calculate the dressed-quark spectral density from the self-consistent solution of the rainbow-truncated gap equation of QCD at temperatures above T{sub c}, the critical temperature for chiral symmetry restoration. We find that, besides the normal and plasmino modes, the spectral function exhibits an essentially nonperturbative zero mode at the temperatures above but near T{sub c}. In the vicinity of T{sub c}, this long-wavelength mode contains the bulk of the spectral strength. So long as this mode persists, the system may reasonably be described as a strongly-coupled state of matter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2011

Phase Diagram and Critical End Point for Strongly Interacting Quarks

We introduce a method based on chiral susceptibility, which enables one to draw a phase diagram in the chemical-potential-temperature plane for strongly interacting quarks whose interactions are described by any reasonable gap equation, even if the diagrammatic content of the quark-gluon vertex is unknown. We locate a critical end point at ({mu}{sup E},T{sup E}){approx}(1.0,0.9)T{sub c}, where T{sub c} is the critical temperature for chiral-symmetry restoration at {mu}=0, and find that a domain of phase coexistence opens at the critical end point whose area increases as a confinement length scale grows.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗