scholarly journals Decoupling of dust cloud and embedding plasma for high electron depletion in nanodusty plasmas

2022 ◽  
Author(s):  
Andreas Petersen ◽  
Oguz Asnaz ◽  
Benjamin Tadsen ◽  
Franko Greiner
Keyword(s):  
Dust Cloud ◽  
High Electron ◽  
Free Electrons ◽  
Ion Density ◽  
Dust Density ◽  
Argon Discharge ◽  
Nanodusty Plasmas ◽  
First Time ◽  
Weak Influence ◽  
Free Plasma

Abstract In recent years nanoparticles (nps) have become key technological products, e.g. as coatings with tunable optical gap in third generation solar cells, as nanocrystals for photonic applications, and as pharmaceutical nanocarriers. In particle sources, that use reactive, nanodusty plasmas, a high dust density changes the properties of the dusty plasma compared to a dust free plasma considerably, as the electron depletion leads to a reduced number of free electrons. This is called the Havnes effect and was central for the understanding of the famous spokes in Saturns rings. We see here, that it is also important for technological applications. Using self excited dust density waves (DDW) as a diagnostic tool, it is possible for the first time, to completely characterize an argon discharge with embedded amorphous hydrocarbon nps of different size and density. The results show, that electron depletion governs the charge of dust grains, while the size of the particles has only a weak influence. The ion density and electric potential profile are almost independent of both, dust size as well as dust density. This suggests, that the rf generated plasma and the dust cloud coexist and coupling of both is weak.

Ion transport in electrode sheath with non-uniform dusts

2002 ◽  
Vol 68 (4) ◽  
pp. 249-255
Author(s):  
A. P. SUN ◽  
X. M. QIU ◽  
H. H. TONG ◽  
Q. C. CHEN
Keyword(s):  
Ion Transport ◽  
Dust Particles ◽  
Uniform Density ◽  
Key Factors ◽  
Ion Density ◽  
Factors Affecting ◽  
Dust Density ◽  
Dust Charge ◽  
The Monte Carlo Method ◽  
Electrode Sheath

The Monte Carlo method is used to simulate ion transport in an Ar plasma electrode sheath with a non-uniform dust. Charge exchange and elastic collisions between ions and neutral atoms and also the collection and Coulomb scattering of ions on the dust particles are examined during the motion of ions in the sheath. In order to study the effect of the non-uniform dust density and size on ion transport, we choose an exponent dust density distribution with a uniform dust size and a normal dust radius distribution with a uniform density and compare the simulation results with those for a uniform dust. It is found that both a non-uniform and a uniform dust density affect the ion density arriving at the electrode significantly and to the same degree. At the same time, it is also found that a non-uniform and uniform dust size influence the ion density arriving at the electrode greatly, but with a slight difference. Therefore, although the dust content is very low in most processing plasmas, its influence becomes evident whether its content is uniform or non-uniform in content and size. So, we can come to the conclusion that the key factors affecting the influence of dust particles on plasma behaviour are the linear density and the average radius of dust particles rather than their distribution.

Analysis of USP Laser Induced Ablation Threshold in Transparent Aqueous Tissue

2012 ◽  
Author(s):  
Jian Jiao ◽  
Zhixiong Guo
Keyword(s):  
Electron Density ◽  
Free Electron ◽  
Present Model ◽  
Ablation Threshold ◽  
Ablation Process ◽  
Free Electrons ◽  
Free Electron Density ◽  
Avalanche Ionization ◽  
Transparent Media ◽  
First Time

The ultrashort pulsed (USP) laser induced plasma-mediated ablation in transparent media is modeled and studied in this work. We propose that a certain number of free electrons are required to trigger the avalanche ionization for the first time. Based on this assumption, the ablation process is postulated as two separate processes — the multiphoton and avalanche ionizations. For USP laser induced ablation in the transparent corneal epithelium at 800 nm, the critical seed free-electron density and the time to initialize the avalanche ionization for pulse widths from picoseconds down to the femtoseconds range are calculated. It is found that the critical seed free-electron density decreases as the pulse width increases, obeying a tp−5.65 rule. Moreover, this model is also extended to the estimation of crater sizes in USP laser ablation of polydimethylsiloxane (PDMS). The crater sizes ablated in a PDMS by a 900 fs pulsed laser at wavelength 1552 nm are modeled using the present model, and the results match with the existing experimental measurements.

Device and Circuit Models of Monolithic InAlN/GaN NAND and NOR Logic Cells Comprising D- and E-Mode HEMTs

2019 ◽  
Vol 28 (supp01) ◽  
pp. 1940009
Author(s):  
Aleš Chvála ◽  
Lukáš Nagy ◽  
Juraj Marek ◽  
Juraj Priesol ◽  
Daniel Donoval ◽  
...  
Keyword(s):  
Dynamic Performance ◽  
High Electron Mobility Transistors ◽  
Logic Circuits ◽  
High Electron ◽  
Enhancement Mode ◽  
Electron Mobility Transistors ◽  
Dual Gate ◽  
Logic Cells ◽  
First Time

This paper presents monolithic integrated InAlN/GaN NAND and NOR logic cells comprising depletion-mode, enhancement-mode and dual-gate enhancement-mode high electron mobility transistors (HEMTs). The designed NAND and NOR logic cells consist of the depletion-mode and enhancement-mode HEMT transistors integrated onto a single die. InAlN/GaN-based NAND and NOR logic cells with good static and dynamic performance are demonstrated for the first time. Calibrated static and dynamic electrophysical models are proposed for 2D device simulations in Sentaurus Device environment. Sentaurus Device mixed-mode setup interconnects the transistors to NAND and NOR logic circuits which allows analysis and characterization of the devices as a complex system. Circuit models of depletion-mode, enhancement-mode and dual-gate HEMTs are designed and calibrated by experimental results and 2D device simulations. The proposed models exhibit highly accurate results.

High-Quality Polycrystalline Silicon Thin Film Prepared by a Solid Phase Crystallization Method

1994 ◽  
Vol 358 ◽  
Author(s):  
T. Baba ◽  
T. Matsuyama ◽  
T. Sawada ◽  
T. Takahama ◽  
K. Wakisaka ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Solid Phase ◽  
Silicon Film ◽  
Columnar Structure ◽  
High Electron ◽  
Silicon Thin Film ◽  
Solid Phase Crystallization ◽  
Crystallization Method ◽  
First Time ◽  
Polycrystalline Silicon Film

ABSTRACTWe succeeded, for the first time, in depositing a silicon film which features 1000Å-wide single-crystalline grains embedded in a matrix of amorphous tissue. The deposition was done by plasma-enhanced CVD from silane diluted with hydrogen at a considerably high temperature (550°C). 5pm-thick undoped amorphous silicon film was deposited on the above film and was crystallized by a solid phase crystallization method. The polycrystalline silicon film which was obtained has a columnar structure and shows an extremely high electron mobility of 808 cm2/Vs.

scholarly journals Evidence for the Primo Vascular System above the Epicardia of Rat Hearts

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ho-Sung Lee ◽  
Jeong Yim Lee ◽  
Dae-In Kang ◽  
Se Hoon Kim ◽  
Inhyung Lee ◽  
...  
Keyword(s):  
Mast Cells ◽  
Rat Heart ◽  
Vascular System ◽  
Blue Staining ◽  
High Electron ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Rat Hearts ◽  
Hematoxylin And Eosin ◽  
First Time

We for the first time reported evidence for the existence of a novel network, a PVS, abovethe epicardium of the rat heart. (1) We were consecutively able to visualize the PVs and the PNs above the epicardial spaces of five rats’ hearts by using Cr-Hx spraying or injection. (2) Hematoxylin and eosin (H&E) and toluidine blue staining of the PVs and the PNs showed that they consisted of a basophilic matrix; specifically the PNs contained several mast cells, some of which were degranulating into pericardial space. Also, 4′, 6-diamidino-2 phenylindole (DAPI) images of the PVs and the PNs showed that they contained various kinds of cells. (3) Transmission electron microscopic (TEM) longitudinal image of the PVs showed that the sinuses contained many granules with high-electron-density cores in parallel with putative endothelial cells. (4) TEM images of the PNs demonstrated that they consisted of lumen-containing cells surrounded by fibers and that they had mast cells that were degranulating toward the epicardium of the rat heart. The above data suggest that mast-cells-containing novel network exists above the epicardium of the rat heart.

scholarly journals Particle-In-Cell Simulations of the Cassini Spacecraft’s Interaction with Saturn’s Ionosphere during the Grand Finale

2021 ◽  
Author(s):  
Zeqi Zhang ◽  
Ravindra T Desai ◽  
Yohei Miyake ◽  
Hideyuki Usui ◽  
Oleg Shebanits
Keyword(s):  
Three Dimensional ◽  
Potential Gradient ◽  
Ion Concentration ◽  
Negative Ion ◽  
High Electron ◽  
Free Electrons ◽  
Field Orientation ◽  
Particle In Cell ◽  
Spacecraft Potential ◽  
Charged Ions

Abstract A surprising and unexpected phenomenon observed during Cassini’s Grand Finale was the spacecraft charging to positive potentials in Saturn’s ionosphere. Here, the ionospheric plasma was depleted of free electrons with negatively charged ions and dust accumulating up to over 95 % of the negative charge density. To further understand the spacecraft-plasma interaction, we perform a three dimensional Particle-In-Cell study of a model Cassini spacecraft immersed in plasma representative of Saturn’s ionosphere. The simulations reveal complex interaction features such as electron wings and a highly structured wake containing spacecraft-scale vortices. The results show how a large negative ion concentration combined with a large negative to positive ion mass ratio is able to drive the spacecraft to the observed positive potentials. Despite the high electron depletions, the electron properties are found as a significant controlling factor for the spacecraft potential together with the magnetic field orientation which induces a potential gradient directed across Cassini’s asymmetric body. This study reveals the global spacecraft interaction experienced by Cassini during the Grand Finale and how this is influenced by the unexpected negative ion and dust populations.

scholarly journals Interhemispheric conjugate effect in longitude variations of mid-latitude ion density

2020 ◽  
Author(s):  
Yiding Chen ◽  
Libo Liu ◽  
Huijun Le ◽  
Hui Zhang
Keyword(s):  
Solar Minimum ◽  
Neutral Wind ◽  
Ion Density ◽  
Flux Tubes ◽  
The Earth ◽  
Defense Meteorological Satellite Program ◽  
June Solstice ◽  
Magnetic Flux Tubes ◽  
First Time ◽  
Meteorological Satellite

<p>Interhemispheric coupling between the northern and southern mid-lattitude ionosphere through the plasmasphere is difficult to confirm directly from observations. A possible result induced by this coupling is interhemispheric conjugacy of the mid-latitude ionosphere. In this paper, interhemispheric conjugate effect in longitude variations of mid-latitude total ion density (N<sub>i</sub>) is presented, for the first time, using the Defense Meteorological Satellite Program (DMSP) measurements; northern and southern N<sub>i</sub> longitude variations at 21:30 LT are similar between magnetically conjugate mid-latitudes around solar minimum June Solstice of 1996. The conjugate effect after sunset also occurs around the June Solstice in other solar minimum years but disappears when solar activity increases. We suggested that mid-latitude interhemispheric coupling is responsible for the conjugate effect. Neutral wind induced ionospheric transport causes topside longitude variations via upward diffusion at summer mid-latitudes; this further induces similar longitude variations of topside N<sub>i</sub> at winter mid-latitudes via the summer to winter interhemispheric coupling. The conjugate effect occurs only inside the plasmapause where magnetic flux tubes are closed and the plasma in these tubes can stably corotate with the Earth. The conjugate effect not only proves mid-latitude interhemispheric coupling through the plasmasphere, but also implies that neutral wind induced transport can affect ionospheric coupling to the plasmasphere at mid-latitudes.</p>

Modeling of Direct Current Atmospheric Pressure Argon Discharge in Two-Dimensional

2014 ◽  
Vol 852 ◽  
pp. 597-601
Author(s):  
Xue Yun Huang ◽  
Ting Ting Zhang ◽  
Xi Zhang
Keyword(s):  
Atmospheric Pressure ◽  
Comsol Multiphysics ◽  
Plasma Properties ◽  
Electric Voltage ◽  
Ion Density ◽  
Atom Density ◽  
Dc Discharge ◽  
Current Voltage ◽  
Argon Discharge ◽  
Good Agreement

The finite element computational package COMSOL multiphysics were used to simulate a bar plate dc discharge in argon at atmospheric pressure. The basic plasma properties such as electron density, ion density, metastable atom density, electron temperature, electric voltage and electric field were studied. The current-voltage (I-V) characteristic of numerical model is in good agreement well with experimental data. This model is simple and insightful as a theoretical tool for argon atmospheric pressure discharges.

Low Temperature Poly-Si Layers Deposited by Hot Wire CVD Yielding a Mobility of 4.0 cm2V−1s−1 in Top Gate Thin Film Transistors

2000 ◽  
Vol 609 ◽  
Author(s):  
R.E.I. Schropp ◽  
J.K. Rath ◽  
B. Stannowski ◽  
C.H.M. Van Der Werf ◽  
Y. Chen ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Low Temperature ◽  
Thin Film Transistors ◽  
Polycrystalline Silicon ◽  
High Electron ◽  
Hot Wire ◽  
High Electron Mobility ◽  
Cvd Method ◽  
First Time

ABSTRACTDirect deposition of polycrystalline silicon (poly-Si) thin films by the Hot Wire CVD method has been used for the first time for the fabrication of poly-Si top gate Thin Film Transistors (TFTs). The TFTs have a high electron mobility in saturation of up to 4 cm2V−1s−1 as well as a remarkably large ON/OFF ratio of up to 6 × 105.

scholarly journals Simulation of Cold Atmospheric Plasma Generated by Floating-Electrode Dielectric Barrier Pulsed Discharge Used for the Cancer Cell Necrosis

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1405
Author(s):  
Samira Elaissi ◽  
Kamel Charrada
Keyword(s):  
Electron Density ◽  
Cancer Cell ◽  
Atmospheric Plasma ◽  
High Electron ◽  
Dielectric Thickness ◽  
Dielectric Barrier ◽  
Melanoma Cancer ◽  
Argon Discharge ◽  
Plasma Device ◽  
Floating Electrode

A numerical simulation of a pulsed floating electrode dielectric barrier discharge (FE-DBD) at atmospheric pressure, used for melanoma cancer cell therapy, is performed using a plasma model in COMSOL Multiphysics software. Distributions of electron density, space charge, and electric field are presented at different instants of the pulsed argon discharge. Significant results related to the characteristics of the plasma device used, the inter-electrodes distance, and the power supply are obtained to improve the efficiency of FE-DBD apparatus for melanoma cancer cell treatment. The FE-DBD presents a higher sensitivity to short pulse durations, related to the accumulated charge over the dielectric barrier around the powered electrode. At higher applied voltage, more energy is injected into the discharge channel and an increase in electron density and electric consumed power is noted. Anticancer activity provided by the FE-DBD plasma is improved using a small interelectrode distance with a high electron emission coefficient and a high dielectric constant with a small dielectric thickness, allowing higher electron density, generating reactive species responsible for the apoptosis of tumor cells.

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