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1.
A magnetized, low-β plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton
and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼1011 cm−3, ∼4 × 1010 cm −3 and ∼2 × 1010 cm −3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive
to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations (ω < ω
ci) are observed and identified as flute modes. Here ω
ci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the
fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute
modes to understand the relevance of some of our experimental observations. 相似文献
2.
A. Andreoni M. Bondani G.M. D'Ariano M.G.A. Paris 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):415-421
We propose a novel scheme for the joint generation of two squeezed beams at arbitrary frequencies ω
1 and ω
2. The scheme consists of two successive steps, both involving nonlinear interactions in χ(2) crystals. The dynamics of the setup is analyzed both quantum mechanically and classically within the parametric approximation.
An experimental implementation involving the fundamental and the harmonics of a Nd:YAG laser pulse, and β-BaB
2
O
4 nonlinear crystals is suggested.
Received 17 May 2000 and Received in final form 9 October 2000 相似文献
3.
V. I. Ritus 《Journal of Experimental and Theoretical Physics》1998,87(1):25-34
This paper discusses the symmetry of the wave field that lies to the right and left of a two-sided accelerated mirror in 1+1
space and satisfies a single condition on it. The symmetry is embodied in the Bogolyubov matrix coefficients α and β that connect the two complete sets of solutions of the wave equations. The amplitudes of the quantum processes in the right
and left half-spaces are expressed in terms of α and β and are related to each other by the transformation (12). The coefficient β
ω′ω
*
plays the role of the source amplitude of a pair of oppositely directed particles with frequencies ω and ω′ of which one is in the left half-space and the other is in the right half-space because one of them has undergone reflection.
Such an interpretation makes β
ω′ω
*
observable and explains why, as shown by Eq. (1) and found earlier by Nikishov and Ritus [Zh. éksp. Teor. Fiz. 108, 1121 (1995); transl. JETP 81, 615 (1995)] and by Ritus [Zh. éksp. Teor. Fiz. 110, 526 (1996); transl. JETP 83, 282 (1996)], the emission spectra of a mirror in 1+1 space coincide with those of charges in 3+1 space. The reason is that
the angular momentum of the pair emitted by the mirror coincides with the angular momentum of the single particle emitted
by the charge.
Zh. éksp. Teor. Fiz. 114, 46–62 (July 1998) 相似文献
4.
The total energy, the equilibrium lattice spacing, and the bulk modulus of the observed phases of zirconium are calculated
by the full-potential LMTO method. Quantitative agreement with experiment is obtained for the volume and pressure of the structural
transition ω → β. The behavior and prominent features of the electronic structure for Zr phases existing at high pressure are discussed, along
with the role of the ground 4p states in the transition ω → β.
Fiz. Tverd. Tela (St. Petersburg) 39, 1933–1934 (November 1997) 相似文献
5.
The temperature dependence of the hyperfine field of substitutional111Cd in antiferromagnetic CoO has been measured by means of the perturbed angular correlation technique. The Larmor frequency
ωL is found to obey a power law ωL(t=ω0
t
β) up tot
max=0.4 wheret=1−T/T
N is the reduced temperature withT
N=291.2(3) K and β=0.393 (5) the critical exponent. The results are discussed and compared with PAC experiments on111Cd in NiO and Ni and with results obtained by other methods. 相似文献
6.
Summary Within the generalized equilibrium statistics recently introduced by Tsallis (p
n
∝[1−β(q−-1)
εn
]1/(q−)), we calculate the thermal dependence of the specific heat corresponding to a harmonic-oscillator-like spectrum, namely ε
n
ω(n−α) (∀ω>0,n=0,1,2,...). The influences ofq and α are exhibited. Physically inaccessible and/or thermally frozen gaps are obtained in the low-temperature region, and,
forq>1, oscillations are observed in the high-temperature region. The specific heat of the two-level system is also shown. 相似文献
7.
The electronic, structural, and thermodynamic properties of the TiZr equiatomic alloy have been calculated in terms of the
electron density functional theory and Debye-Grüneisen model. The calculated lattice parameters a and c/a agree well with experimental data for the α, ω, and β phases. It has been shown that the ω phase is stable at atmospheric
pressure and low temperatures, and it remains energetically more favorable up to T = 600 K. In the temperature range 600 K < T < 900 K, the α phase becomes stable, and above 900 K, the β phase of the TiZr alloy is stable. The phase diagram constructed
in this study agrees qualitatively with the available experimental data. A tendency toward separation of the TiZr equiatomic
alloy in the ω phase has been analyzed. It has been demonstrated that, in the ground state, the TiZr equiatomic alloy in the
ω phase exhibits a tendency toward ordering rather than toward phase separation. 相似文献
8.
For the standard map the homotopically non-trivial invariant curves of rotation number ω satisfying the Bryuno condition
are shown to be analytic in the perturbative parameter ε, provided |ε| is small enough. The radius of convergence ρ(ω) of
the Lindstedt series – sometimes called critical function of the standard map – is studied and the relation with the Bryuno function B(ω) is derived: the quantity |log ρ(ω) + 2 B (ω)| is proved to be bounded uniformly in ω.
Received: 8 February 2000/ Accepted: 2 March 2001 相似文献
9.
V. N. Gridnev 《JETP Letters》1999,69(7):546-550
It is shown that the contribution of low-frequency excitations with characteristic energy ℏω
l to T-odd (nonreciprocal) optical effects, including spatial dispersion effects, at optical frequencies ω≫ω
l can be calculated in the zeroth-order approximation with respect to the parameter ω
l/ω. This greatly simplifies their analysis. Some of these effects are found to be frequency independent in the spectral regions
where the refractive index n(ω)≈ const. It is shown that frequency-independent Faraday rotation can be observed in media with zero magnetization, including
in media with zero microscopic magnetic moment density.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 7, 510–513 (10 April 1999) 相似文献
10.
M. Yu. Sudakov 《Technical Physics》2000,45(3):322-329
Variations in the spectral composition of ion oscillations within several stability regions of a quadrupole mass filter were
studied. The frequency spectrum was shown to consist of two line systems. Side lines ωn=nω0±βω0/2 were observed in the oscillation spectrum near harmonics nω0 (n=0, 1, 2,...), where ω0 is the circular frequency of an RF field and β is the stability parameter. Near the boundaries of the stability regions,
the oscillations took the form of beatings. For even values of the stability parameter, β=2k (k=1, 2,...), the beat frequency coincides with the fundamental frequency ω0 and, for β=2k−1, the main beat frequencies are ω0/2 and 3ω0/2. 相似文献
11.
Hassan Amirhashchi Anirudh Pradhan H. Zainuddin 《International Journal of Theoretical Physics》2011,50(11):3529-3543
We study the evolution of the dark energy parameter in a spatially homogeneous and isotropic FRW space-time filled with barotropic
fluid and dark energy by considering a time dependent deceleration parameter. Two cases are discussed when the dark energy
is minimally coupled to the perfect fluid as well as direct interaction with it. It is concluded that in both non-interacting
and interacting cases only open and flat universes cross the phantom region. We find that during the evolution of the universe,
the equation of state (EoS) for dark energy ω
D
changes from ω
D
>−1 to ω
D
<−1, which is consistent with recent observations. The cosmic jerk parameter in our derived models is also found to be in
good agreement with the recent data of astrophysical observations. 相似文献
12.
Anil Kumar Yadav Farook Rahaman Saibal Ray 《International Journal of Theoretical Physics》2011,50(3):871-881
The dark energy models with variable equation of state parameter ω are investigated by using law of variation of Hubble’s parameter that yields the constant value of deceleration parameter.
Here the equation of state parameter ω is found to be time dependent and its existing range for this model is consistent with the recent observations of SN Ia data,
SN Ia data (with CMBR anisotropy) and galaxy clustering statistics. The physical significance of the dark energy models have
also been discussed. 相似文献
13.
14.
Ronggang Tian Jiuxun Sun Wei Yang Xinying Xue Fei Yu 《Central European Journal of Physics》2008,6(3):704-710
The analytic mean-field approach (AMFP) was applied to study the thermodynamic properties of Zirconium (Zr). The analytic
expressions for the Helmholtz free energy, internal energy and equation of state have been derived. The formalism for the
case of the Morse potential is used in this work. The four potential parameters are determined by fitting the molar volume
of the three phases of Zr. The calculated molar volume of α, β and ω Zr are in fairly good agreement with the available experimental data. The results presented in this paper verify that the
AMFP is a useful approach to study the thermodynamic properties of Zr. Furthermore, we predict the variation of the relationship
of free energy and internal energy versus the molar volume at various temperatures and the dependence of the bulk modulus,
the thermal expansion coefficient and the heat capacity on temperature at zero pressure of α, β and ω Zr.
相似文献
15.
Kyung-Min Lee Sang-Kwon Lee Tae-Youl Choi 《Applied Physics A: Materials Science & Processing》2012,106(4):955-960
We developed a reliable and highly reproducible way of fabricating a one-stop measurement platform for characterizing the
thermoelectric properties of individual nanowires (NWs) using a focused ion beam and a nanomanipulator. 3-ω and 1-ω signals obtained by the four-point-probe method were used in measuring the thermal and electrical conductivities of the NW.
Subsequently, the Seebeck coefficient was measured by using additional nanoelectrodes including a nanoheater. The thermal
conductivity of the single β-SiC NW was obtained at 86.5±3.5 W/mK. The Seebeck coefficient was obtained to be −1.21 mV/K by using the same measurement
platform. Thus, the dimensionless figure of merit, ZT=σS
2
T/k, was measured to be ∼0.12. This value is around 120 times higher than the reported maximum value of bulk β-SiC. 相似文献
16.
Molin Liu Jianbo Lu Yuanxing Gui 《The European Physical Journal C - Particles and Fields》2009,59(1):107-116
On the basis of the 4D momentum, the influence of quintessence on the gravitational frequency shift and the deflection of
light are examined in modified Schwarzschild space. We find that the frequency of a photon depends on the state parameter
of the quintessence w
q: the frequency increases for −1<w
q<−1/3 and decreases for −1/3<w
q<0. Meanwhile, we adopt an integral power number a (a=3ω
q+2) to solve the orbital equation of photon. The photon’s potentials become higher with the decrease of ω
q. The behavior of the bending light sensitively depends on the state parameter ω
q. In particular, for the case of ω
q=−1, there is no influence on the deflection of light by quintessence. Furthermore, according to the H-masers of the GP-A
redshift experiment and long-baseline interferometry, the constraints on the quintessence field in the solar system are presented
here. 相似文献
17.
The spectral dependence of the electron-phonon relaxation rate γe−ph(ℏω) in metals is studied in pump-supercontinuum-probe (PSCP) experiments with femtosecond time resolution. Investigation
of this spectral dependence, which exhibits a substantial slowing of the relaxation rate γe−ph(ℏω) near the Fermi level E
F
, using the parametrization γe−ph(ℏω)∝λ〈Ω2〉 (ℏω−E
F
)2 makes it possible to determine directly the electron-phonon interaction parameter λ〈Ω2〉. The parameter λ〈Ω2〉 for YBa2Cu3O7−δ is analyzed using this method.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 5, 329–332 (10 September 1999) 相似文献
18.
We eliminate by KAM methods the time dependence in a class of linear differential equations in ℓ2 subject to an unbounded, quasi-periodic forcing. This entails the pure-point nature of the Floquet spectrum of the operator
H
0+εP(ωt) for ε small. Here H
0 is the one-dimensional Schr?dinger operator p
2+V, V(x)∼|x|α, α <2 for |x|→∞, the time quasi-periodic perturbation P may grow as |x|β, β <(α−2)/2, and the frequency vector ω is non resonant. The proof extends to infinite dimensional spaces the result valid
for quasiperiodically forced linear differential equations and is based on Kuksin's estimate of solutions of homological equations
with non-constant coefficients.
Received: 3 October 2000 / Accepted: 20 December 2000 相似文献
19.
Summary In this paper we exhibit analytical solutions for the upwelling and the coastal currents induced by periodic wind stress.
We present solutions for an infinite deep ocean and for a shallow ocean. There is upwelling only when the period of the forcing
is longer than the inertial period,i.e. f>ω. When the period of the forcing is shorter than the inertial period,i.e. f<ω, there is not upwelling, but propagating waves are excited.
Paper presented at the IV Congresso del Gruppo Nazionale per la Fisica dell'Atmosfera e dell'Oceano, June 22–24, 1987, Rome 相似文献
20.
David Trnka 《Pramana》2006,66(5):915-920
Recent experimental results on the in-medium modification of the ω meson are discussed. The experiment described was performed
at the ELSA accelerator facility in Bonn using the combined detector system of Crystal Barrel and TAPS. Theω-meson was identified via the reaction γ+A → ω +X → π0 γ +X 相似文献