共查询到20条相似文献,搜索用时 46 毫秒
1.
涡旋光束的产生、传输与应用是当前光学领域热门的研究课题之一.本文提出的新型多环涡旋光束,包括双环涡旋及三环涡旋光束,它是由多束携带不同拓扑电荷数且束腰半径不同的拉盖尔-高斯涡旋光束共轴叠加而成,其光强分布为多环结构.从理论上研究了多环涡旋光束的形成与分布特征,基于共轭对称延拓Fourier计算全息方法生成了多环涡旋光束的计算全息图,并利用一个空间光调制器实验产生了与理论一致的高质量的多环涡旋光束.研究表明多环涡旋光束的各环携带不同的轨道角动量,空间分布保持相互独立.这种新型的多环涡旋光束相对于携带单一拓扑电荷数的涡旋光束,提供了更多的控制参数和更加多样化的结构分布,因此在光学镊子、光学捕获等微操控以及光通信领域具有潜在的应用潜力. 相似文献
2.
《Physics letters. A》1987,121(7):342-346
The uniformity of plasma density in multipolar devices can be attributed to the trapping of primary electrons in the cusped magnetic field. This trapping may be due to an ion acoustic instability initiated by the diamagnetic drift of plasma electrons. 相似文献
3.
《Physics letters. A》1997,236(3):223-226
The parallel velocity shear instability (PVSI) is experimentally investigated in a double-ended Q machine in which the shear in the ion flow is produced by suitable shaping of the axial magnetic field. Instability fluctuation levels approaching nearly 100% are often observed. 相似文献
4.
S. V. Iordanski 《JETP Letters》2009,89(7):362-363
It was shown that the ground states obtained by the projection on the states of the lowest Landau level are unstable due to
the formation of the isolated vortex decreasing the energy at the partial L1 fillings. This statement is valid due to the
different dependence on the sample size of the various terms in the free energy like the free energy of the rotating liquid
irrelevant to the details of the microscopical structure and the interaction.
The article is published in the original. 相似文献
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6.
Experimental dynamics of a vortex within a vortex 总被引:1,自引:0,他引:1
We report the experimental dynamics of a new two-dimensional (2D) fluid phenomenon that occurs when an intense, pointlike vortex is placed within a diffuse, circular vortex. Our observations, made using strongly magnetized electron columns to model the 2D fluid, support the analysis performed by Jin and Dubin. 相似文献
7.
We carry out an experimental and theoretical study of the focusing properties of a Gaussian Schell-model (GSM) vortex beam. It is found that we can shape the beam profile of the focused GSM vortex beam by varying its initial spatial coherence width. Focused dark hollow, flat-topped, and Gaussian beam spots can be obtained in our experiment, which will be useful for trapping particles. The experimental results agree well with the theoretical results. 相似文献
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9.
We report here the first observation of the Taylor vortex wavy instability in the Couette flow of liquid helium. The experimental results agree qualitatively with those of classical liquids. However, the instability occurs in a wider range of Reynolds numbers. 相似文献
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The physics of vortex lines in dipolar condensates is studied. Because of the nonlocality of the dipolar interaction, the 3D character of the vortex plays a more important role in dipolar gases than in typical short-range interacting ones. In particular, the dipolar interaction significantly affects the stability of the transverse modes of the vortex line. Remarkably, in the presence of a periodic potential along the vortexline, the spectrum of transverse modes shows a rotonlike minimum, which eventually destabilizes the straight vortex when the BEC as a whole is still stable, opening the possibility for new scenarios for vortex-line configurations in dipolar gases. 相似文献
12.
An attractive Bose-Einstein condensate with a vortex splits into two pieces via the quadrupole dynamical instability, which arises at a weaker strength of interaction than the monopole and the dipole instabilities. The split pieces subsequently unite to restore the original vortex or collapse. 相似文献
13.
C. Duprat C. Ruyer-Quil F. Giorgiutti-Dauphiné 《The European physical journal. Special topics》2009,166(1):63-66
The wavy dynamics of a viscous film flowing axisymmetrically on a vertical fiber is characterized experimentally. The study
of the initial response of the flow to natural noise shows a well-defined transition between a convective and an absolute
instability
[1]. In the convective case, disturbances of controlled frequencies have been applied at inlet. The flow responds to inlet
excitation at frequencies lower than a well-defined cut-off frequency. A good agreement has been found with the linear stability
analysis and with the solution to a two-equation
model [2] in the nonlinear regime. 相似文献
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15.
在入口温度、压力不变的条件下,改变冷流比,分别对不同冷流比工况下的涡流管内温度分布进行了实验测试,同时对不同冷流比工况下的实验结果进行比较,研究表明:在同一轴向端面处,温度由轴心向壁面呈现不断增大的趋势,在壁面附近处达到最大值;在同一径向位置处,温度随着轴向位置的增大不断增大,在涡流室的轴心处,温度达到最低,而在热端出口的壁面处,温度达到最大。在冷流比为0.1563时,温度沿径向呈增大趋势,而在冷流比为0.7158时,温度沿径向呈现先降低后增大的趋势;在实验研究范围内,同一测点处,温度随冷流比的增大而增大。 相似文献
16.
The predicted shear-induced shift of the wave phase velocity, the essence of the shear-modified ion-acoustic (SMIA) instability mechanism that reduces ion Landau damping for otherwise damped ion-acoustic waves [V. Gavrishchaka et al., 80, 728 (1998)], is verified with direct measurements in a strongly magnetized laboratory plasma. The SMIA growth rate is shown to increase with increasing shear, as predicted. SMIA wave propagation is shown to be possible at both small and large angles to the magnetic field, consistent with space observations of ion-acoustic-like waves. 相似文献
17.
Shin Y Saba M Vengalattore M Pasquini TA Sanner C Leanhardt AE Prentiss M Pritchard DE Ketterle W 《Physical review letters》2004,93(16):160406
Doubly quantized vortices were topologically imprinted in /F=1> 23Na condensates, and their time evolution was observed using a tomographic imaging technique. The decay into two singly quantized vortices was characterized and attributed to dynamical instability. The time scale of the splitting process was found to be longer at higher atom density. 相似文献
18.
Demosthenes Kivotides 《Physics letters. A》2018,382(22):1481-1485
It is shown that, as a result of its interactions with superfluid vorticity, a normal-fluid vortex tube in helium-4 becomes unstable and disintegrates. The superfluid vorticity acquires only a small (few percents of normal-fluid tube strength) polarization, whilst expanding in a front-like manner in the intervortex space of the normal-fluid, forming a dense, unstructured tangle in the process. The accompanied energy spectra scalings offer a structural explanation of analogous scalings in fully developed finite-temperature superfluid turbulence. A macroscopic mutual-friction model incorporating these findings is proposed. 相似文献
19.
I. M. Dubrovskii 《Journal of Experimental and Theoretical Physics》1997,84(5):1022-1026
Because of attraction of the parallel currents forming an Abrikosov vortex, the vortex energy per unit length decreases, under
bending of the vortex, by a quantity proportional to the square of the curvature. Solving the London equation in an approximation
allowing for this effect makes it possible to calculate the energy of an Abrikosov vortex in the form of a helix whose length
and pitch are much larger than the correlation length, whose curvature is small compared to the reciprocal London length,
and whose slope in relation to an axis coinciding with the direction in which the vortex energy is the highest is also small.
When the anisotropy is large, which is characteristic of high-T
c superconductors, the energy of such an Abrikosov vortex is lower than that of a straight Abrikosov vortex. Certain consequences
of the fact that the Abrikosov vortices in a high-T
c superconductor are helical are discussed. Among these is a phase transition that breaks the symmetry between Abrikosov vortices
shaped like right-and left-hand helixes in relation to the magnetic field.
Zh. éksp. Teor. Fiz. 111, 1869–1878 (May 1997) 相似文献