scholarly journals Optical trapping by petal-like circular Airy beam

2020 ◽  
Author(s):  
Vahid Shahabadi ◽  
Daryoush Abdollahpour
Keyword(s):  
Optical Trapping ◽  
Radial Distance ◽  
Transverse Field ◽  
Axial Direction ◽  
Axial Position ◽  
Trapped Particles ◽  
Airy Beam ◽  
Tight Focusing ◽  
New Type ◽  
Beam Parameters

Abstract Superposition of two circular Airy vortex beams (CAVB), with opposite sign topological charges (l), produces a new type of petal beams called petal-like circular Airy beam (PCAB) with a transverse field distribution in the form of azimuthally modulated concentric rings that follow Airy function over the radial distance on a transverse plane. In this paper, tight focusing of truncated PCAB and its application in optical trapping is numerically investigated. It is shown that by adjusting the beam parameters four different trapping configurations can be achieved: a single transverse trap at a single axial position, a multi-trap geometry at a single axial position, two single transverse traps at two positions along the axial direction, and two multi-trap geometries at two different axial positions. It is also shown that the number of trapped particles in the multi-trap configurations is 2l per focal plane, while the number of axial trap positions is determined by the truncation aperture size. Finally, trap stiffnesses and corresponding potential energies for the trapping configurations are presented and discussed.

scholarly journals The first observation of 4D tomography measurement of plasma structures and fluctuations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chanho Moon ◽  
Kotaro Yamasaki ◽  
Yoshihiko Nagashima ◽  
Shigeru Inagaki ◽  
Takeshi Ido ◽  
...  
Keyword(s):  
Steady State ◽  
Three Dimensional ◽  
Axial Direction ◽  
Axial Position ◽  
Entire Cross Section ◽  
Helicon Plasma ◽  
Emission Profile ◽  
Dimensional Measurement ◽  
Tomography System ◽  
Three Dimensional Measurement

AbstractA tomography system is installed as one of the diagnostics of new age to examine the three-dimensional characteristics of structure and dynamics including fluctuations of a linear magnetized helicon plasma. The system is composed of three sets of tomography components located at different axial positions. Each tomography component can measure the two-dimensional emission profile over the entire cross-section of plasma at different axial positions in a sufficient temporal scale to detect the fluctuations. The four-dimensional measurement including time and space successfully obtains the following three results that have never been found without three-dimensional measurement: (1) in the production phase, the plasma front propagates from the antenna toward the end plate with an ion acoustic velocity. (2) In the steady state, the plasma emission profile is inhomogeneous, and decreases along the axial direction in the presence of the azimuthal asymmetry. Furthermore, (3) in the steady state, the fluctuations should originate from a particular axial position located downward from the helicon antenna.

Experimental Investigation of Divider Plate Assisted Thermocline Storage

2015 ◽  
Author(s):  
Daniel S. Codd
Keyword(s):  
Experimental Investigation ◽  
Storage Capacity ◽  
Axial Position ◽  
Working Fluid ◽  
Storage Efficiency ◽  
Round Trip ◽  
Internal Loss ◽  
Baseline Case ◽  
Loss Prediction ◽  
New Type

A new type of single-tank thermal energy storage (TES) with an actuated, loose-fitting insulated divider plate positioned between the hot and cold fluids is described, based on the CSPonD volumetric molten salt thermal receiver with integrated TES concept. A 240 L lab-scale assisted thermocline tank was fabricated and tested using water as the working fluid, connected to a 5 kW heat addition and extraction loop. The axial position of the divider plate was controlled to follow the thermocline interface as energy was added or removed under various charge-store-discharge profiles. For 6 hour storage cycles, the divider plate tank exhibited a round-trip storage efficiency of 0.53, compared to 0.46 for the baseline tank, a 14% improvement. Output temperatures remained within 90% of initial values for 89% of the divider plate tank volume, as compared to only 58% for the baseline case, representing a 53% improvement in usable storage capacity. Internal conduction losses were found to be less for the divider plate tank and correlated well with models (measured 83–93% values vs 86% internal loss prediction).

scholarly journals Different Alfvén wave acceleration processes of electrons in substorms at ~4-5 <i>R<sub>E</sub></i> and 2-3 <i>R<sub>E</sub></i> radial distance

2004 ◽  
Vol 22 (6) ◽  
pp. 2213-2227 ◽  
Author(s):  
P. Janhunen ◽  
A. Olsson ◽  
J. Hanasz ◽  
C. T. Russell ◽  
H. Laakso ◽  
...  
Keyword(s):  
Electric Field ◽  
Ion Beam ◽  
Radial Distance ◽  
Alfven Wave ◽  
Physical Mechanisms ◽  
Spacecraft Potential ◽  
New Type ◽  
Statistical Studies ◽  
Frequency Changes ◽  
Substorm Onsets

Abstract. Recent statistical studies show the existence of an island of cavities and enhanced electric field structures at 4-5RE radial distance in the evening and midnight magnetic local time (MLT) sectors in the auroral region during disturbed conditions, as well as ion beam occurrence frequency changes at the same altitude. We study the possibility that the mechanism involved is electron Landau resonance with incoming Alfvén waves and study the feasibility of the idea further with Polar electric field, magnetic field, spacecraft potential and electron data in an event where Polar maps to a substorm over the CANOPUS magnetometer array. Recently, a new type of auroral kilometric radiation (AKR) emission originating from ~2-3RE radial distance, the so-called dot-AKR emission, has been reported to occur during substorm onsets and suggested to also be an effect of Alfvénic wave acceleration in a pre-existing auroral cavity. We improve the analysis of the dot-AKR, giving it a unified theoretical handling with the high-altitude Landau resonance phenomena. The purpose of the paper is to study the two types of Alfvénic electron acceleration, acknowledging that they have different physical mechanisms, altitudes and roles in substorm-related auroral processes.

scholarly journals Technical Applicability of Low-Swirl Fuel Nozzle for a Liquid-Fueled Industrial Gas Turbine Combustor

2012 ◽  
Author(s):  
Masamichi Koyama ◽  
Shigeru Tachibana
Keyword(s):  
Gas Turbine ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Flame Stabilization ◽  
Axial Position ◽  
Axial Distance ◽  
Gas Turbine Combustor ◽  
Lifted Flame ◽  
Fuel Nozzle ◽  
Industrial Gas Turbine

This paper explores the technical applicability of a low-swirl fuel nozzle designed for use with a liquid-fueled industrial gas turbine combustor. Particle image velocimetry was applied to measure nozzle flow fields with an open methane-air premixed flame configuration. Herein we discuss the effects of the chamfer dimensions of the nozzle tip on flow characteristics. The profiles indicate parallel shifts in axial direction that depend on chamfer dimensions. When velocity is normalized by bulk velocity and plotted against axial distance from the virtual origins, the profiles are consistent. This means that chamfer dimensions primarily affect the axial position of the flame, while keeping other flow characteristics, such as global stretch rate, unchanged. Then, the atmospheric combustion test was conducted with kerosene in a single-can combustor. Lifted flame stabilization was confirmed by observing the flames through a window. Lastly, an engine test was performed to assess the technical applicability of the fuel nozzle under real engine conditions. The engine testbed was a 290 kW simple-cycle liquid-fueled gas turbine engine. The configurations of the fuel nozzle were consistent with the ones used in the PIV and the atmospheric combustion test. Wall temperatures close to the fuel nozzle exit were within the acceptable range, even without the cooling air required with conventional combustors. This is an advantage of the lifted flame stabilization technique. NOx emissions were below maximum levels set under current Japanese regulations (<84 ppm@15% O2). In sum, the proposed fuel nozzle design shows promise for use with liquid-fueled industrial gas turbine engines.

The Effect of Laser Beam Welding Parameters onto the Evolving Joints Geometry

2017 ◽  
Vol 885 ◽  
pp. 178-183 ◽  
Author(s):  
Miklós Berczeli ◽  
Gábor Buza
Keyword(s):  
Laser Beam ◽  
Laser Welding ◽  
Feed Rate ◽  
Laser Beam Welding ◽  
Spot Size ◽  
Welding Parameters ◽  
Beam Focusing ◽  
Metallographic Cross Section ◽  
New Type ◽  
Beam Parameters

In our research the effect of a new type of laser beam parameters during the laser welding have been investigated with 80 different welding parameters. The laser welding parameters such as the laser power, laser beam spot size on the surface and feed rate greatly affect the resulting weld geometry. S235 grade steel has been used. The operating equipment was a Trumpf 4001 4 kW disk laser with a diameter of 100 microns optical fiber. The effect of different welding parameters were evaluated from the metallographic cross-section of the welded joints. This article describes the effect of the different laser beam focusing and the welding feed rate.

scholarly journals Cubic-Phase Metasurface for Three-Dimensional Optical Manipulation

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1730
Author(s):  
Hsin Yu Kuo ◽  
Sunil Vyas ◽  
Cheng Hung Chu ◽  
Mu Ku Chen ◽  
Xu Shi ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Visible Region ◽  
Axial Direction ◽  
Spatial Light Modulators ◽  
Biological Research ◽  
Optical Manipulation ◽  
Cubic Phase ◽  
Self Healing ◽  
Airy Beam ◽  
3D Manipulation

The optical tweezer is one of the important techniques for contactless manipulation in biological research to control the motion of tiny objects. For three-dimensional (3D) optical manipulation, shaped light beams have been widely used. Typically, spatial light modulators are used for shaping light fields. However, they suffer from bulky size, narrow operational bandwidth, and limitations of incident polarization states. Here, a cubic-phase dielectric metasurface, composed of GaN circular nanopillars, is designed and fabricated to generate a polarization-independent vertically accelerated two-dimensional (2D) Airy beam in the visible region. The distinctive propagation characteristics of a vertically accelerated 2D Airy beam, including non-diffraction, self-acceleration, and self-healing, are experimentally demonstrated. An optical manipulation system equipped with a cubic-phase metasurface is designed to perform 3D manipulation of microscale particles. Due to the high-intensity gradients and the reciprocal propagation trajectory of Airy beams, particles can be laterally shifted and guided along the axial direction. In addition, the performance of optical trapping is quantitatively evaluated by experimentally measured trapping stiffness. Our metasurface has great potential to shape light for compact systems in the field of physics and biological applications.

Response of an Infinite Elastic Medium to Traveling Loads in a Cylindrical Bore

1969 ◽  
Vol 36 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Raymond Parnes
Keyword(s):  
Elastic Medium ◽  
Wave Front ◽  
Initial Conditions ◽  
Moving Load ◽  
Radial Distance ◽  
Longitudinal Direction ◽  
Axial Direction ◽  
Arbitrary Distribution ◽  
Line Load ◽  
Angular Coordinate

A line load applied along a transverse circle travels in the axial direction along the interior of a circular bore in an infinite elastic medium. The line load has an arbitrary distribution in the angular coordinate along the circumference of the circle and moves with a constant velocity V which is greater than the propagation velocities of the dilatational and equivoluminal waves in the elastic medium. Disregarding initial conditions at far distances, steady-state solutions which do not change in a coordinate system which moves with the velocity V of the moving load are obtained for the stresses and displacements at points in the medium. The components of the applied line loads are expanded into a Fourier series in terms of the angular coordinate. Expressions for the stress and displacement components at points in the medium are derived for each term of the series as a function of the radial distance from the cavity axis and the longitudinal distance behind the wave front. Numerical results are presented for the axisymmetric case for both the stress and displacement components on the cavity boundary. Corresponding results are also given for the case in which the applied boundary tractions have step distributions in the longitudinal direction behind the wave front.

Turbulent Air Flow Over Rough Surfaces: Mean Flow Parameters

1984 ◽  
Vol 106 (4) ◽  
pp. 405-409 ◽  
Author(s):  
J. J. Stukel ◽  
P. K. Hopke ◽  
K. Nourmohammadi
Keyword(s):  
Axial Flow ◽  
Axial Direction ◽  
Roughness Height ◽  
Axial Position ◽  
Mean Flow ◽  
Mean Velocity ◽  
Flow Parameters ◽  
Turbulent Flow Structure ◽  
Turbulent Air Flow ◽  
Logarithmic Equation

The objective of the study was to examine experimentally the turbulent flow structure near a repeated-rib geometry rough-walled surface as a function of the ratio of roughness height to pipe radius (K/R), the ratio of spacing between the elements to roughness height (P/K), and the axial position with the rib cycle. The centerline axial flow velocity was found to vary sinusoidally in the axial direction within a rib cycle for P/K>10 for K/R = 0.1437 and P/K>13 for K/R = 0.100. The roughness effect on the mean velocity profiles was characterized using a logarithmic equation which utilized an error in origin and a roughness function that was a function of the error in origin. The equation was found to be valid for P/K values of 7 or less for K/R = 0.1437 and 13 for K/R = 0.1 geometries.

Optical trapping and manipulation of Mie particles with Airy beam

2016 ◽  
Vol 18 (2) ◽  
pp. 025607 ◽  
Author(s):  
Ziyu Zhao ◽  
Weiping Zang ◽  
Jianguo Tian
Keyword(s):  
Optical Trapping ◽  
Airy Beam
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