scholarly journals On the Field Focusing Effect at the Tungsten Fuzzy Nanostructures Formed by Helium Plasmas

2021 ◽  
Vol 16 (0) ◽  
pp. 1405107-1405107
Author(s):  
Katsuaki TANABE
Keyword(s):  
Focusing Effect

An improved magnetic prism design for a transmission electron microscope energy filter

1978 ◽  
Vol 36 (1) ◽  
pp. 40-41 ◽  
Author(s):  
John W. Andrew ◽  
F.P. Ottensmeyer ◽  
E. Martell
Keyword(s):  
Energy Resolution ◽  
Symmetry Plane ◽  
Fringe Field ◽  
Focal Distance ◽  
Electron Trajectories ◽  
Focusing Effect ◽  
Transmission Electron ◽  
Path Lengths ◽  
Electron Microscopes ◽  
Focusing Properties

Energy selecting electron microscopes of the Castaing-Henry prism-mirror-prism design suffer from a loss of image and energy resolution with increasing field of view. These effects can be qualitatively understood by examining the focusing properties of the prism shown in Fig. 1. A cone of electrons emerges from the entrance lens crossover A and impinges on the planar face of the prism. The task of the prism is to focus these electrons to a point B at a focal distance f2 from the side of the prism. Electrons traveling in the plane of the diagram (i.e., the symmetry plane of the prism) are focused toward point B due to the different path lengths of different electron trajectories in the triangularly shaped magnetic field. This is referred to as horizontal focusing; the better this focusing effect the better the energy resolution of the spectrometer. Electrons in a plane perpendicular to the diagram and containing the central ray of the incident cone are focused toward B by the curved fringe field of the prism.

Focusing of inertial particles after the shock-wave intersection point

2007 ◽  
Vol 5 ◽  
pp. 145-150
Author(s):  
I.V. Golubkina
Keyword(s):  
Shock Wave ◽  
Mass Concentration ◽  
Gas Flow ◽  
Intersection Point ◽  
Plane Shock ◽  
Inertial Particles ◽  
Dusty Gas ◽  
Focusing Effect ◽  
Aerodynamic Focusing ◽  
Particle Mass Concentration

The effect of the aerodynamic focusing of inertial particles is investigated in both symmetric and non-symmetric cases of interaction of two plane shock waves in the stationary dusty-gas flow. The particle mass concentration is assumed to be small. Particle trajectories and concentration are calculated numerically with the full Lagrangian approach. A parametric study of the flow is performed in order to find the values of the governing parameters corresponding to the maximum focusing effect.

scholarly journals Anomalous Beam Transport through Gabor (Plasma) Lens Prototype

2021 ◽  
Vol 11 (10) ◽  
pp. 4357
Author(s):  
Toby Nonnenmacher ◽  
Titus-Stefan Dascalu ◽  
Robert Bingham ◽  
Chung Lim Cheung ◽  
Hin-Tung Lau ◽  
...  
Keyword(s):  
Cost Effective ◽  
Stable Operation ◽  
High Electron ◽  
Beam Transport ◽  
Focusing Effect ◽  
Energy Proton ◽  
Diocotron Instability ◽  
Strong Focusing ◽  
Axis Rotation ◽  
Mev Protons

An electron plasma lens is a cost-effective, compact, strong-focusing element that can ensure efficient capture of low-energy proton and ion beams from laser-driven sources. A Gabor lens prototype was built for high electron density operation at Imperial College London. The parameters of the stable operation regime of the lens and its performance during a beam test with 1.4 MeV protons are reported here. Narrow pencil beams were imaged on a scintillator screen 67 cm downstream of the lens. The lens converted the pencil beams into rings that show position-dependent shape and intensity modulation that are dependent on the settings of the lens. Characterisation of the focusing effect suggests that the plasma column exhibited an off-axis rotation similar to the m=1 diocotron instability. The association of the instability with the cause of the rings was investigated using particle tracking simulations.

Influence of the focusing effect on XAFS in ReO3, WO3−x and FeF3

1995 ◽  
Vol 208-209 ◽  
pp. 45-46 ◽  
Author(s):  
A. Kuzmin ◽  
J. Purans ◽  
Ph. Parent
Keyword(s):  
Focusing Effect

Discussion on Structural, Optical, Thermal, Mechanical, Dielectric and Third-Order NLO Properties of 3-Nitroanilinium Chloride Single Crystals for Optoelectronic Applications

2021 ◽  
Author(s):  
C. S. JULIET BRINTHA ◽  
S.E JOEMA
Keyword(s):  
Single Crystal ◽  
Mechanical Stability ◽  
Damage Threshold ◽  
Space Charge Polarization ◽  
Laser Damage Threshold ◽  
Closed Aperture ◽  
Third Order ◽  
Suitable Material ◽  
Focusing Effect ◽  
Optoelectronic Applications

Abstract Preferable, third-order nonlinear optical (NLO) single crystal, 3-Nitroanilinium chloride (3NACL) was auspiciously synthesised by slow evaporation technique. The crystal system of synthesised 3NACL crystal is triclinic with centrosymmetric space group was identified by single crystal XRD studies. All the functional groups present in the sample and its respective vibrations are analysed through FTIR analysis. UV-Vis transmittance spectrum revealed that the synthesised material was 83% transmittance and it cut-off wavelength was 276nm. The mechanical stability and thermal property of grown 3NACL crystals were ascertained by Vickers micro hardness analysis and TG/DTA analysis. The intermolecular interaction of the 3NACL was scrutinized by Hirshfeld surface analysis. Dielectric studies revealed that dielectric constant and dielectric loss were high at lower frequency region due to the space charge polarization. Inclusion free 3NACL crystal was used to analyse the Laser damage threshold (LDT) studies and its calculated LDT value was 4.3 GW/cm2. The third-order NLO parameters (β = 7.5472x10− 12 m/W, η2 = 5.6931x10− 19 m2/W, χ3 = 2.9491x10− 13 esu) of the 3NACL material was statutory evaluated by Z-scan studied. Here, β and η2 are positive value due to the saturated absorption and self-focusing effect was observed in open and closed aperture z-scan curve. Above all these findings 3NACL was suitable material for NLO and optoelectronic applications.

Optimization of profile and damping layer of plates embedded with acoustic black hole indentations for broadband energy dissipation

2022 ◽  
pp. 1045389X2110721
Author(s):  
Wei Huang ◽  
Chongcong Tao ◽  
Hongli Ji ◽  
Jinhao Qiu
Keyword(s):  
Black Hole ◽  
Energy Dissipation ◽  
Vibration Suppression ◽  
Optimal Solution ◽  
Simultaneous Optimization ◽  
Optimal Arrangement ◽  
Focusing Effect ◽  
Upper Limit ◽  
And Topology ◽  
Design Variables

Acoustic Black Hole (ABH) plate structure has shown promising potentials of vibration suppression above a cut on frequency. For energy dissipation below the cut on frequency, however, the ABH is less effective due to the absence of wave focusing effect. This work reports a simultaneous optimization of ABH plates for broadband energy dissipation. Two sets of design variables of ABH plates, that is, geometry of the profile and topology of the damping layer, are optimized in an alternatively nested procedure. A novel objective function, namely the upper limit of kinetic energy, is proposed. Modeling of ABH structures is implemented and dynamic characteristic is solved using finite element method. A rectangular plate embedded with two ABH indentations is presented as a numerical example. Influence of frequency ranges in the calculation and mass ratios of the damping layer on results are discussed. The achieved optimal arrangement of the damping layer is found to cover equally, if not more, above the non-ABH (uniform) part of the plate than the ABH area. This is inconsistent with the conventional believe that damping layers should cover as much of the ABH area as possible. Mechanism of the broadband energy dissipation by the optimal solution is demonstrated.

scholarly journals Acoustic Forward Model for Guided Wave Propagation and Scattering in a Pipe Bend

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 486
Author(s):  
Carlos-Omar Rasgado-Moreno ◽  
Marek Rist ◽  
Raul Land ◽  
Madis Ratassepp
Keyword(s):  
Wave Propagation ◽  
Three Dimensional ◽  
Scattered Wave ◽  
Rectangular Domain ◽  
Guided Wave ◽  
Forward Model ◽  
Pipe Bend ◽  
Focusing Effect ◽  
Main Challenge ◽  
Local Point

The sections of pipe bends are hot spots for wall thinning due to accelerated corrosion by fluid flow. Conventionally, the thickness of a bend wall is evaluated by local point-by-point ultrasonic measurement, which is slow and costly. Guided wave tomography is an attractive method that enables the monitoring of a whole bend area by processing the waves excited and received by transducer arrays. The main challenge associated with the tomography of the bend is the development of an appropriate forward model, which should simply and efficiently handle the wave propagation in a complex bend model. In this study, we developed a two-dimensional (2D) acoustic forward model to replace the complex three-dimensional (3D) bend domain with a rectangular domain that is made artificially anisotropic by using Thomsen parameters. Thomsen parameters allow the consideration of the directional dependence of the velocity of the wave in the model. Good agreement was found between predictions and experiments performed on a 220 mm diameter (d) pipe with 1.5d bend radius, including the wave-field focusing effect and the steering effect of scattered wave-fields from defects.

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