Modal Focusing Effect of Positive and Negative Ions by a Three-Dimensional Plasma-Sheath Lens

2005 ◽  
Vol 94 (12) ◽  
Author(s):  
E. Stamate ◽  
H. Sugai
Keyword(s):  
Three Dimensional ◽  
Negative Ions ◽  
Plasma Sheath ◽  
Focusing Effect

scholarly journals Mass-resolved electronic circular dichroism ion spectroscopy

Science ◽  
2020 ◽  
Vol 368 (6498) ◽  
pp. 1465-1468 ◽  
Author(s):  
Steven Daly ◽  
Frédéric Rosu ◽  
Valérie Gabelica
Keyword(s):  
Circular Dichroism ◽  
Three Dimensional ◽  
Polarized Light ◽  
Negative Ions ◽  
Data Interpretation ◽  
Electronic Circular Dichroism ◽  
Circularly Polarized Light ◽  
Chiral Compounds ◽  
Electron Photodetachment ◽  
Circular Dichroïsm

DNA and proteins are chiral: Their three-dimensional structures cannot be superimposed with their mirror images. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with an ultraviolet nanosecond optical parametric oscillator laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resembled those of their solution-phase counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.

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.

Oscillations of Magnetized Dust Grains in Plasma Sheath with Negative Ions

2007 ◽  
Vol 24 (7) ◽  
pp. 2003-2005 ◽  
Author(s):  
Gan Bao-Xia ◽  
Chen Yin-Hua
Keyword(s):  
Negative Ions ◽  
Plasma Sheath ◽  
Dust Grains

scholarly journals The focusing effect of electron flow and negative refraction in three-dimensional topological insulators

2017 ◽  
Vol 19 (10) ◽  
pp. 103028
Author(s):  
Kai-Tong Wang ◽  
Yanxia Xing ◽  
King Tai Cheung ◽  
Jian Wang ◽  
Hui Pan ◽  
...  
Keyword(s):  
Topological Insulators ◽  
Negative Refraction ◽  
Electron Flow ◽  
Three Dimensional ◽  
Focusing Effect

Ion-acoustic waves in a degenerate multicomponent magnetoplasma

2012 ◽  
Vol 79 (2) ◽  
pp. 163-168 ◽  
Author(s):  
U. M. ABDELSALAM ◽  
M. M. SELIM
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Three Dimensional ◽  
Negative Ions ◽  
Expansion Method ◽  
Reductive Perturbation Method ◽  
Negative Ion ◽  
Zk Equation ◽  
Ion Acoustic ◽  
Astrophysical Objects

AbstractThe hydrodynamic equations of positive and negative ions, degenerate electrons, and the Poisson equation are used along with the reductive perturbation method to derive the three-dimensional Zakharov–Kuznetsov (ZK) equation. The G′/G-expansion method is used to obtain a new class of solutions for the ZK equation. At certain condition, these solutions can describe the solitary waves that propagate in our plasma. The effects of negative ion concentrations, the positive/negative ion cyclotron frequency, as well as positive-to-negative ion mass ratio on solitary pulses are examined. Finally, the present study might be helpful to understand the propagation of nonlinear ion-acoustic solitary waves in a dense plasma, such as in astrophysical objects.

scholarly journals Development of an MTF in ADINA and its application to the study of the Yuxi Basin effect

2021 ◽  
Author(s):  
Tiefei Li ◽  
Xueliang Chen ◽  
Zongchao Li
Keyword(s):  
Numerical Simulation ◽  
Seismic Waves ◽  
Velocity Structure ◽  
Three Dimensional ◽  
Site Effect ◽  
Lumped Mass ◽  
Explicit Finite Element ◽  
Focusing Effect ◽  
Infinite Domains ◽  
Simulation Results

AbstractA three-dimensional multitransmitting formula is developed in ADINA to simulate the input of seismic waves and the scattering of infinite domains at the same time, consistent with the progress of the explicit finite element method of lumped mass. A three-dimensional cube model is built, and a delta pulse wave is input to compare the simulation results with the analytical solutions. The simulation results show that the peak error is 0.2% of the input wave, which meets the requirements of the usual numerical simulation. This method has a certain efficiency advantage in site effect analyses of fine models for localized fields. A velocity structure model of the Yuxi Basin is built, and the associated basin effect is studied by numerical simulation. The distribution of the focusing effect is related to the structure of the narrow east-west and wide north-south features in the Yuxi Basin, and the edge effect is related to the slope of the basin base. A distribution map is given of the amplification effect of ground motion in the basin.

Sign in / Sign up

Export Citation Format

Share Document