1,018 research outputs found
Effect of impurities on the transition between minority ion and mode conversion ICRH heating in (3He)-H tokamak plasmas
Hydrogen majority plasmas will be used in the initial non-activated phase of
ITER operation. Optimizing ion cyclotron resonance heating (ICRH) in such
scenarios will help in achieving H-mode in these plasmas. Past JET experiments
with the carbon wall revealed a significant impact of intrinsic impurities on
the ICRH performance in (3He)-H plasmas relevant for the full-field initial
ITER phase. High plasma contamination with carbon impurities resulted in the
appearance of a supplementary mode conversion layer and significant reduction
in the transition concentration of 3He minority ions, defined as the
concentration at which the change from minority heating to mode conversion
regime occurs. In view of the installation of the new ITER-like wall at JET, it
is important to evaluate the effect of Be and W impurities on ICRH scenarios in
(3He)-H plasmas. In this paper, an approximate analytical expression for the
transition concentration of 3He minority ions is derived as a function of
plasma and ICRH parameters, and accounting for typical impurity species at JET.
The accompanying 1D wave modeling supports the analytical results and suggests
a potential experimental method to reduce 3He level needed to achieve a
specific heating regime by puffing a small amount of 4He ions additionally to
(3He)-H plasma.Comment: 23 pages, 9 figure
Temperature dependent anisotropy of the penetration depth and coherence length in MgB$_2
We report measurements of the temperature dependent anisotropies
( and ) of both the London penetration depth
and the upper critical field of MgB. Data for
was obtained from measurements of
and on a single crystal sample using a tunnel diode
oscillator technique. was
deduced from field dependent specific heat measurements on the same sample.
and have opposite temperature dependencies, but
close to tend to a common value (). These results are in good agreement with theories
accounting for the two gap nature of MgBComment: 4 pages with figures (New version
de Haas-van Alphen effect investigation of the electronic structure of Al substituted MgB_2
We report a de Haas-van Alphen (dHvA) study of the electronic structure of Al
doped crystals of MgB. We have measured crystals with % Al which
have a of 33.6 K, (% lower than pure MgB). dHvA frequencies
for the tube orbits in the doped samples are lower than in pure
MgB, implying a reduction in the number of holes in this sheet of
Fermi surface. The mass of the quasiparticles on the larger orbit is
lighter than the pure case indicating a reduction in electron-phonon coupling
constant . These observations are compared with band structure
calculations, and found to be in excellent agreement.Comment: 4 pages with figure
Generalized Penner models to all genera
We give a complete description of the genus expansion of the one-cut solution
to the generalized Penner model. The solution is presented in a form which
allows us in a very straightforward manner to localize critical points and to
investigate the scaling behaviour of the model in the vicinity of these points.
We carry out an analysis of the critical behaviour to all genera addressing all
types of multi-critical points. In certain regions of the coupling constant
space the model must be defined via analytical continuation. We show in detail
how this works for the Penner model. Using analytical continuation it is
possible to reach the fermionic 1-matrix model. We show that the critical
points of the fermionic 1-matrix model can be indexed by an integer, , as it
was the case for the ordinary hermitian 1-matrix model. Furthermore the 'th
multi-critical fermionic model has to all genera the same value of
as the 'th multi-critical hermitian model. However, the
coefficients of the topological expansion need not be the same in the two
cases. We show explicitly how it is possible with a fermionic matrix model to
reach a multi-critical point for which the topological expansion has
alternating signs, but otherwise coincides with the usual Painlev\'{e}
expansion.Comment: 27 pages, PostScrip
Renormalizations in softly broken N=1 theories: Slavnov-Taylor identities
Slavnov-Taylor identities have been applied to perform explicitly the
renormalization procedure for the softly broken N=1 SYM. The result is in
accordance with the previous results obtained at the level of supergraph
technique.Comment: Latex, 17 pages, one statement about soft gauge beta function has
been change
The first data on the infestation of the parti-coloured bat, Vespertilio murinus (Chiroptera, Vespertilionidae), with gamasid mites, Steatonyssus spinosus (Mesostigmata, Gamasina, Macronyssidae)
This article presents one of the very few records of a macronyssid mite (Mesostigmata, Gamasina, Macronyssidae) infestation of vesper bats (Chiroptera, Vespertilionidae). It is the first report of the influence of host parameters on the infestation of the parti-coloured bat, Vespertilio murinus, by the mite Steatonyssus spinosus. It has been shown that the infestation varies considerably throughout the host's occupation of summer roosts and the highest infestation was observed in the post-lactation period. Female bats are infested significantly more intensively than male bats due to changes in their immune status during pregnancy and lactation. The infestation decreases in the period when the breeding colony disbands due to both roost switching and the intensification of grooming during this period. © Russian Journal Of Theriology, 2017
A Review of Symmetry Algebras of Quantum Matrix Models in the Large-N Limit
This is a review article in which we will introduce, in a unifying fashion
and with more intermediate steps in some difficult calculations, two
infinite-dimensional Lie algebras of quantum matrix models, one for the open
string sector and one for the closed string sector. Physical observables of
quantum matrix models in the large-N limit can be expressed as elements of
these Lie algebras. We will see that both algebras arise as quotient algebras
of a larger Lie algebra. We will also discuss some properties of these Lie
algebras not published elsewhere yet, and briefly review their relationship
with well-known algebras like the Cuntz algebra, the Witt algebra and the
Virasoro algebra. We will also review how Yang--Mills theory, various low
energy effective models of string theory, quantum gravity, string-bit models,
and quantum spin chain models can be formulated as quantum matrix models.
Studying these algebras thus help us understand the common symmetry of these
physical systems.Comment: 77 pages, 21 eps figures, 1 table, LaTeX2.09; an invited review
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