scholarly journals Theoretical Study of High-Frequency Response of InGaAs/AlAs Double-Barrier Nanostructures

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Konstantin S. Grishakov ◽  
Vladimir F. Elesin ◽  
Mikhail M. Maslov ◽  
Konstantin P. Katin
Keyword(s):  
Energy Level ◽  
Electric Fields ◽  
Field Amplitude ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Resonant Energy ◽  
High Frequencies ◽  
High Frequency Response ◽  
Ac Electric Fields ◽  
Wide Range

The presented article contains the numerical calculations of the InGaAs/AlAs resonant tunneling diode’s (RTD) response to the AC electric field of a wide range of amplitudes and frequencies. These calculations have been performed within the coherent quantum-mechanical model that is based on the solution of the time-dependent Schrödinger equation with exact open boundary conditions. It is shown that as the field amplitude increases, at high frequencies, where ħω>Γ (Γ is the width of the resonant energy level), the active current can reach high values comparable to the direct current value in resonance. This indicates the implementation of the quantum regime for RTD when radiative transitions are between quasi-energetic levels and the resonant energy level. Moreover, there is an excitement of higher quasi-energetic levels in AC electric fields, which in particular results in a slow droop of the active current as the field amplitude increases. It also results in potentially abrupt changes of the operating point position by the ħω value. This makes it possible to achieve relatively high output powers of InGaAs/AlAs RTD having an order of 105 W/cm2 at high frequencies.

scholarly journals Anomalous Anisotropic Diffusion of Electron Swarms in AC Electric Fields

1995 ◽  
Vol 48 (6) ◽  
pp. 925 ◽  
Author(s):  
RD White ◽  
RE Robson ◽  
KF Ness
Keyword(s):  
Electric Fields ◽  
Diffusion Coefficients ◽  
Anisotropic Diffusion ◽  
Time Varying ◽  
Longitudinal Diffusion ◽  
Temporal Behaviour ◽  
Ac Electric Fields ◽  
Wide Range ◽  
First Time ◽  
And Diffusion

A time-dependent multi-term solution of the Boltzmann equation is used to calculate the drift and diffusion coefficients of electron swarms in gases under the influence of a time varying electric field. Two model gases are considered and for a.c. electric fields results are presented for a wide range of applied frequencies. Of particular interest is the anomalous temporal behaviour of the longitudinal diffusion coefficient, which is discussed here for the first time.

AC Electrokinetic Pumps for Micro/NanoFluidics

2004 ◽  
Author(s):  
Junqing Wu ◽  
Gaurav Soni ◽  
Dazhi Wang ◽  
Carl D. Meinhart
Keyword(s):  
Electric Fields ◽  
Fluid Motion ◽  
Lab On A Chip ◽  
Dna Amplification ◽  
Aqueous Fluid ◽  
Working Fluid ◽  
High Frequencies ◽  
Electrode Surfaces ◽  
Ac Electric Fields ◽  
Micro Channels

We have developed micropumps for microfluidics that use AC electric fields to drive aqueous fluid motion through micro channels. These pumps operate at relatively low voltages (~5–10Vrms), and high frequencies (~100kHz). They have several distinct advantages over the DC electrokinetic pumps. The low voltages make the pumps well suited for a wide variety of biosensor and “Lab-on-a-Chip” applications (e.g. PCR chip for DNA amplification). The high frequencies minimize electrolysis, so that bubbles do not form on the electrode surfaces, and do not contaminate the working fluid. The pumps can also be used as active valves or precision micro-dispensers.

AC electrohydrodynamic instabilities in thin liquid films

2009 ◽  
Vol 631 ◽  
pp. 255-279 ◽  
Author(s):  
SCOTT A. ROBERTS ◽  
SATISH KUMAR
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Electric Fields ◽  
Linear Stability Analysis ◽  
Floquet Theory ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Dielectric Films ◽  
High Frequencies ◽  
Ac Electric Fields

When DC electric fields are applied to a thin liquid film, the interface may become unstable and form a series of pillars. In this paper, we apply lubrication theory to examine the possibility of using AC electric fields to exert further control over the size and shape of the pillars. For perfect dielectric films, linear stability analysis shows that the influence of an AC field can be understood by considering an effective DC field. For leaky dielectric films, Floquet theory is applied to carry out the linear stability analysis, and it reveals that high frequencies may be used to inhibit the accumulation of interfacial free charge, leading to a lowering of growth rates and wavenumbers. Nonlinear simulations confirm the results of the linear stability analysis while also uncovering additional mechanisms for tuning overall pillar height and width. The results presented here may be of interest for the controlled creation of surface topographical features in applications such as patterned coatings and microelectronics.

scholarly journals Radiative kinetic simulations of steady-state relativistic plasmoid magnetic reconnection

2020 ◽  
Vol 497 (2) ◽  
pp. 1365-1381 ◽  
Author(s):  
José Ortuño-Macías ◽  
Krzysztof Nalewajko
Keyword(s):  
Steady State ◽  
Magnetic Reconnection ◽  
Plasma Temperature ◽  
Open Boundary ◽  
Radiative Cooling ◽  
Current Layer ◽  
Open Boundary Conditions ◽  
Radiation Process ◽  
Particle In Cell ◽  
Wide Range

ABSTRACT We present the results of two-dimensional particle-in-cell (PIC) simulations of relativistic magnetic reconnection (RMR) in electron–positron plasma, including the dynamical influence of the synchrotron radiation process, and integrating the observable emission signatures. The simulations are initiated with a single Harris current layer with a central gap that triggers the RMR process. We achieve a steady-state reconnection with unrestricted outflows by means of open boundary conditions. The radiative cooling efficiency is regulated by the choice of initial plasma temperature Θ. We explore different values of Θ and of the background magnetization σ0. Throughout the simulations, plasmoids are generated in the central region of the layer, and they evolve at different rates, achieving a wide range of sizes. The gaps between plasmoids are filled by smooth relativistic outflows called minijets, whose contribution to the observed radiation is very limited due to their low-particle densities. Small-sized plasmoids are rapidly accelerated; however, they have lower contributions to the observed emission, despite stronger relativistic beaming. Large-sized plasmoids are slow but produce most of the observed synchrotron emission, with major part of their radiation produced within the central cores, the density of which is enhanced by radiative cooling. Synchrotron light curves show rapid bright flares that can be identified as originating from mergers between small/fast plasmoids and large/slow targets moving in the same direction. In the high-magnetization case, the accelerated particles form a broken power-law energy distribution with a soft tail produced by particles accelerated in the minijets.

Fabrication of ZrO 2 /rGO nanocomposites by flash sintering under AC electric fields

2021 ◽  
Author(s):  
Xinghua Su ◽  
Mengying Fu ◽  
Gai An ◽  
Zhihua Jiao ◽  
Qiang Tian ◽  
...  
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields ◽  
Flash Sintering

scholarly journals Impurity induced scale-free localization

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Linhu Li ◽  
Ching Hua Lee ◽  
Jiangbin Gong
Keyword(s):  
Boundary Conditions ◽  
Skin Effect ◽  
Reciprocal Lattice ◽  
Periodic Boundary Conditions ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Translational Invariance ◽  
Scale Free ◽  
Special Cases ◽  
Simulation Results

AbstractNon-Hermitian systems have been shown to have a dramatic sensitivity to their boundary conditions. In particular, the non-Hermitian skin effect induces collective boundary localization upon turning off boundary coupling, a feature very distinct from that under periodic boundary conditions. Here we develop a full framework for non-Hermitian impurity physics in a non-reciprocal lattice, with periodic/open boundary conditions and even their interpolations being special cases across a whole range of boundary impurity strengths. We uncover steady states with scale-free localization along or even against the direction of non-reciprocity in various impurity strength regimes. Also present are Bloch-like states that survive albeit broken translational invariance. We further explore the co-existence of non-Hermitian skin effect and scale-free localization, where even qualitative aspects of the system’s spectrum can be extremely sensitive to impurity strength. Specific circuit setups are also proposed for experimentally detecting the scale-free accumulation, with simulation results confirming our main findings.

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