135 research outputs found
Effect of Electron Energy Distribution Function on Power Deposition and Plasma Density in an Inductively Coupled Discharge at Very Low Pressures
A self-consistent 1-D model was developed to study the effect of the electron
energy distribution function (EEDF) on power deposition and plasma density
profiles in a planar inductively coupled plasma (ICP) in the non-local regime
(pressure < 10 mTorr). The model consisted of three modules: (1) an electron
energy distribution function (EEDF) module to compute the non-Maxwellian EEDF,
(2) a non-local electron kinetics module to predict the non-local electron
conductivity, RF current, electric field and power deposition profiles in the
non-uniform plasma, and (3) a heavy species transport module to solve for the
ion density and velocity profiles as well as the metastable density. Results
using the non-Maxwellian EEDF model were compared with predictions using a
Maxwellian EEDF, under otherwise identical conditions. The RF electric field,
current, and power deposition profiles were different, especially at 1mTorr,
for which the electron effective mean free path was larger than the skin depth.
The plasma density predicted by the Maxwellian EEDF was up to 93% larger for
the conditions examined. Thus, the non-Maxwellian EEDF must be accounted for in
modeling ICPs at very low pressures.Comment: 19 pages submitted to Plasma Sources Sci. Techno
Mass spectra of doubly heavy Omega_QQ' baryons
We evaluate the masses of baryons composed of two heavy quarks and a strange
quark with account for spin-dependent splittings in the framework of potential
model with the KKO potential motivated by QCD with a three-loop beta-function
for the effective charge consistent with both the perturbative limit at short
distances and linear confinement term at long distances between the quarks. The
factorization of dynamics is supposed and explored in the nonrelativistic
Schroedinger equation for the motion in the system of two heavy quarks
constituting the doubly heavy diquark and the strange quark interaction with
the diquark. The limits of approach, its justification and uncertainties are
discussed. Excited quasistable states are classified by the quantum numbers of
heavy diquark composed by the heavy quarks of the same flavor.Comment: 14 pages, revtex4-file, 3 eps-figures, 5 tables, typos correcte
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
The principle of an assembly with a capacity of 1000 m3/h for working fireclay in inclined beds
Method for the intermittent optimization of the working of a block by a rotary excavator
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