共查询到20条相似文献,搜索用时 46 毫秒
1.
Evolution of polarization of electromagnetic waves in a plasma with uniformly sheared magnetic field
S. E. Segre 《Il Nuovo Cimento D》1991,13(6):821-826
Summary An analytic solution is found for the evolution of the state of polarization of an electromagnetic wave propagating in a plasma
with uniformly sheared magnetic field. It is the generalization of the one found previously for the special case of propagation
perpendicular to the magnetic field. 相似文献
2.
Summary In this paper the relativistic second-harmonic generation of a high-power laser radiation in a laser-produced plasma has been
studied theoretically in the presence of a self-generated magnetic field. The relativistic Vlasov equation has been employed
for the nonlinear response of the electrons in the hot magnetized plasma. It is observed that the power conversion efficiency
of the generated second harmonic wave is much higher for relativistic calculations than that for nonrelativistic calculations.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
3.
Summary In the framework of the hydrodynamic approximation, we study the Langmuir oscillations of an ion density ripple background
plasma under the influence of a single external harmonic r.f. field. An analytic frequency response curve is derived for the
late-time behaviour exhibiting multistability and hysteresis. 相似文献
4.
Summary This paper presents an investigation of the growth of a radially symmetrical ripple, superimposed on a Gaussian laser beam
in a collisionless magnetoplasma. The effect of the magnetic field and the intensity of the laser on the growth of the ripple
is presented in some detail. The effect of the presence of the ripple on the excitation of an electron plasma wave is also
investigated. Coupling of a weak plasma wave with the main laser beam is through the modified background density. The combined
effect of increased intensity of the laser beam and magnetic field is observed to suppress the growth of the ripple as well
as the excitation of the plasma wave.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
5.
自行研制的等离子体针在大气压下通过介质阻挡放电产生的等离子体,再由喷嘴处安装的漏斗形装置聚焦形成针状等离子体. 然后对针状等离子体的基本特性和杀Enterococcus faecalis(E. faecalis)菌进行了研究,E. faecalis菌是一种引起完善充填根管再感染的主要微生物. 当等离子体针功率为5—28?W时,对等离子体的温度进行了测量,表明它不同于其他热杀菌方式. 通过改变等离子体针内电极末端注入的氧气量,发现适当的氧气量,不仅增加等离子体内含氧粒子的浓度而且对等离子体的长度影响也不明显. 实验表明最佳参数为功率15?W,0.1?m3·h-1氦和2.5%氧气,间距12?mm,处理时间30 s. 为了找出杀菌的关键粒子,进一步比较了大气压下的等离子体针的发射光谱与agar(琼脂)2?mm下的光谱并找出关键粒子.
关键词:
大气压等离子体
介质阻挡放电
E. faecalis菌')" href="#">E. faecalis菌
光谱 相似文献
6.
R. Prasad 《Il Nuovo Cimento D》1991,13(1):81-86
Summary The relaxation process in an ideal magnetohydrodynamic (MHD) plasma with fluid velocity and enclosed in a toroidal vessel
has been discussed. The expressions for the field parameters and the energy state of the system have been derived. The expression
for the minimum energy state of the system has been deduced. An analysis of the conservation of energy of the system in the
presence of weak and strong magnetic fields has also been presented.
The author of this paper has agreed to not receive the proofs for correction.
This work was commenced and partly completed during author's short stay at I.C.T.P.-Trieste, Italy, in 1988. 相似文献
7.
A.A. Mamun A.A. Gebreel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):301-305
A theoretical investigation has been made of nonlinear propagation of ultra-low-frequency electromagnetic waves in a magnetized
two fluid (negatively charged dust and positively charged ion fluids) dusty plasma. These are modified Alfvén waves for small
value of and are modified magnetosonic waves for large , where is the angle between the directions of the external magnetic field and the wave propagation. A nonlinear evolution equation
for the wave magnetic field, which is known as Korteweg de Vries (K-dV) equation and which admits a stationary solitary wave
solution, is derived by the reductive perturbation method. The effects of external magnetic field and dust characteristics
on the amplitude and the width of these solitary structures are examined. The implications of these results to some space
and astrophysical plasma systems, especially to planetary ring-systems, are briefly mentioned.
Received 8 July 1999 and Received in final form 11 October 1999 相似文献
8.
R. Liu M.-L. Liang B. Yuan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):571-578
Pairwise thermal entanglement in the three-qubit XXX
Heisenberg model with next nearest neighbor interaction and a nonuniform
magnetic field has been studied. It's found that the next nearest neighbor
interaction has a great effect on the entanglement between the next nearest
neighbor sites, but has slight effect on the nearest neighbor
entanglement (NNE). Applying a magnetic field at the middle site enhances the
next nearest neighbor entanglement (NNNE) sharply when there is a small field
at the side sites and the next nearest neighbor coupling constant is
positive. A staggered magnetic field helps to maintain nearest neighbor
entanglement obviously. 相似文献
9.
C 《Superlattices and Microstructures》2000,28(5-6)
Charging and discharging phenomena from silicon nanocrystals have been studied by means of capacitance–voltage characteristics on P-type metal-oxide-semiconductor (P-MOS) capacitors with embedded self-assembled silicon quantum dots. The dots have a floating gate behavior as shown by the hysteresis onC –V curves. The Si-dots are charged or discharged by direct tunneling of carriers through a 3 nm thick oxide. The nanocrystals could be charged by electrons or holes, depending on the charging bias conditions. The discharge is studied by constant bias method and shows a logarithmic variation with time. Retention times higher than several hours are observed. A simple model is developed in order to evaluate the electric field within the tunneling oxide layer. Then, complete simulations are done for the different discharge paths. The barrier heights are extracted from the discharge data and possible confinement effects are discussed. The results confirm the high potentiality of silicon nanocrystal-floating gates for memory applications. 相似文献
10.
J. G. Linhart 《Il Nuovo Cimento D》1994,16(3):281-296
Summary In order that a Z-pinch in a DT plasma could spark off an axial nuclear detonation wave severe conditions on space and time
concentration of electromagnetic energy must be satisfied. Such energy compression could be achieved by a magnetic-field compressor
(MFC) in which a fast liner compresses an azimuthal field (B
φ) of a micro Z-pinch. The driver of the MFC could be either a heavy-ion beam or an explosive magnetic-field generator (EMG)
destroyed at each shot. In conclusion, some of the major problems associated with this approach to ICF are outlined. 相似文献
11.
The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves
measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves
to determine the first- and second-order anisotropy constant in these films. In this paper we report a theoretical derivation
of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum
total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles
with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations
are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of
coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is
much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement
provides an effective access to analyze the in-plane anisotropy constant K
3 in hexagonal compounds, and the suitable experimental condition to measure K
3 is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2.
Supported by the National Natural Science Foundation of China (Grant Nos. 90505007 and 10774061)
Recommended by LI FaShen 相似文献
12.
The equilibria of plasma in a dipolar magnetic field under the gravitational influence of a massive body (a star or black hole) and a self gravitating plasma are considered. Analytical solutions are found that can be useful for understanding the physics of plasma flows in accretion disks and star formation. 相似文献
13.
The neutrino-electron scattering in a dense degenerate magnetized plasma under the conditions μ
2 > 2eB ≫ μE is investigated. The volume density of the neutrino energy and momentum losses due to this process are calculated. The results
we have obtained demonstrate that plasma in the presence of an external magnetic field is more transparent for neutrino than
for non-magnetized plasma. It is shown that neutrino scattering under conditions considered does not lead to the neutrino
force acting on plasma. 相似文献
14.
¼ 《Superlattices and Microstructures》2000,28(5-6)
The metal-oxide-semiconductor (MOS) field effect transistor (FET) using ‘oxidized μ c-Si/ultrathin oxide’ gate structure was studied. It was found that this structure shows negative differential resistance behavior, which can be explained by the Coulomb blockade effect of trapped carriers and immediate tunneling into and tunneling out with gate bias variation. The requirements for the device with this structure showing negative differential resistance behavior are based on very weak resistive coupling between floating gate and channel. They are the thinness of the tunnel oxide film, the thickness ratio of the upper oxidized film and the tunnel oxide, and the channel threshold voltage. MOSFET with this gate structure is proposed as a new negative differential resistance device. 相似文献
15.
M. A. Macrì C. Del Gratta L. Di Donato S. Di Luzio G. L. Romani S. Della Penna A. Pasquarelli 《Il Nuovo Cimento D》1994,16(5):425-432
Summary A preliminary study is here reported on a new potential marker for biomagnetic measurements. The marker consists of superparamagnetic
polymer microspheres which were detected in the presence of external steady magnetic fields by means of an r.f.-SQUID magnetometer.
The particles were prepared in samples differing in the concentration value and immersed in a homogeneous magnetic field of
variable intensity. A simple model was taken into account for the distribution of the microspheres in the samples, so that
the theoretical values were compared to the marker field values measured by the biomagnetic sensor. The overall sensitivity
of the experimental apparatus and the minimum concentration value of the marker were then estimated. 相似文献
16.
improvement of electrical properties of Cu/SiCOH low-k film integrated system by O2 plasma treatment 下载免费PDF全文
This paper investigates the effect of O2 plasma treatment on the electric property of Cu/SiCOH low dielectric constant (low-k) film integrated structure. The results show that the leakage current of Cu/SiCOH low-k integrated structure can be reduced obviously at the expense of a slight increase in dielectric constant k of SiCOH films. Bythe Fourier transform infrared (FTIR) analysis on the bonding configurations of SiCOH films treated by O2 plasmar it is found that the decrease of leakage current is related to the increase of Si-O cages originating from the linkage of Si dangling bonds through O, which makes the open pores sealed and reduces the diffusion of Cu to pores. 相似文献
17.
L. Krlín R. Paprok V. Svoboda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):95-109
We model and discuss the possible types of motion that charged particles may
undergo in a stationary and spatially periodic electrostatic potential and a
homogeneous magnetic field. The model is considered to be the simplest
approximation of more complex phenomena of plasma edge turbulence in
tokamaks. Therein, low frequency turbulence appears in the plasma edge,
resulting in a fluctuation of the electron density, and also in the
generation of a turbulent electrostatic field. Typical parameters of this
turbulent electrostatic field are an electrical potential amplitude of
10–100 V and wave numbers k≈103 m-1. In our model, we consider these regimes, together
with a homogeneous magnetic field with a magnitude of 1 T. We investigate the
dynamics of singly-ionized carbon ions – a typical plasma impurity – with
kinetic energies on the order of 10 eV. Besides the obvious
Larmor and drift motions, a motion of random-walk and of Lévy walk
character appear therein.
All of these types of motion can play an important role in the modelling of
the anomalous diffusion of particles from the plasma edge turbulence region.
The dynamics mentioned will cause an inevitable escape of energetic
particles and thus of power loss from the thermonuclear reactor.
Moreover, Lévy walk kinetics represents a very interesting kind of
kinetics, currently of great interest, which was previously not so often
discussed. 相似文献
18.
Control of extraordinary light transmission through perforated metal films using liquid crystals 总被引:1,自引:0,他引:1
Y. M. Strelniker D. Stroud A. O. Voznesenskaya 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(1):1-7
We calculate the effective dielectric tensor of a metal film penetrated by cylindrical holes filled with a nematic liquid
crystal (NLC). We assume that the director of the NLC is parallel to the film, and that its direction within the plane can
be controlled by a
static magnetic field, via the Freedericksz effect. To calculate the effective dielectric tensor, we consider both randomly
distributed holes (using a Maxwell-Garnett approximation) and a
square lattice of holes (using a Fourier technique). Both the holes and the lattice constant of the square lattice are assumed
small compared to the wavelength. The films are found to exhibit
extraordinary light transmission at special frequencies related to
the surface plasmon resonances of the composite film. Furthermore,
the frequencies of peak transmission are found to be substantially
split when the dielectric in the holes is anisotropic. For typical
NLC parameters, the splitting is of order 5–10% of the metal plasma
frequency. Thus, the extraordinary transmission can be controlled by
a static magnetic or electric field whose direction can be rotated
to orient the director of the NLC. Finally, as a practical means
of producing the NLC-filled holes, we consider the case where the
entire perforated metal film is dipped into a pool of NLC,
so that all the holes are filled with the NLC, and there are also
homogeneous slabs of NLC on both sides of the film. The
transmission in this geometry is shown to have similar
characteristics to that in which the NLC-filled screen is placed in air. 相似文献
19.
Local friction at a sliding interface between an elastomer and a rigid spherical probe 总被引:1,自引:0,他引:1
This paper reports on spatially resolved measurements of the shear stress distribution at a frictional interface between a
flat rubber substrate and a glass lens. Silicone rubber specimens marked close to their surface by a colored pattern have
been prepared in order to measure the surface displacement field induced by the steady-state friction of the spherical probe.
The deconvolution of this displacement field then provides the actual shear stress distribution at the contact interface.
When a smooth glass lens is used, a nearly constant shear stress is achieved within the contact. On the other hand, a bell-shaped
shear stress distribution is obtained with rough lenses. These first results suggest that simple notions of real contact area
and constant interface shear stress cannot account for the observed changes in local friction when roughness is varied. 相似文献
20.
F. J. Cao 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):883-885
The quantum dynamics of the symmetry-broken λ(Φ
2)2 scalar-field theory in the presence of an homogeneous external field is investigated in the large-N limit. We consider an initial thermal state of temperature T for a constant external field J. A subsequent sign flip of the external field, J→ - J, gives rise to an out-of-equilibrium nonperturbative quantum field dynamics. We review here the dynamics for the symmetry-broken
λ(Φ
2)2 scalar N component field theory in the large-N limit, with particular stress in the comparison between the results when the initial temperature is zero and when it is finite.
The presence of a finite temperature modifies the dynamical effective potential for the expectation value, and also makes
that the transition between the two regimes of the early dynamics occurs for lower values of the external field. The two regimes
are characterized by the presence or absence of a temporal trapping close to the metastable equilibrium position of the potential.
In the cases when the trapping occurs it is shorter for larger initial temperatures. 相似文献