scholarly journals COMPARISON BETWEEN 2D TURBULENCE MODEL ESEL AND EXPERIMENTAL DATA FROM AUG AND COMPASS TOKAMAKS

2015 ◽  
Vol 55 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Peter Ondac ◽  
Jan Horacek ◽  
Jakub Seidl ◽  
Petr Vondrácek ◽  
Hans Werner Müller ◽  
...  
Keyword(s):  
Turbulent Transport ◽  
Plasma Potential ◽  
Density Fluctuations ◽  
Tokamak Plasma ◽  
Plasma Parameters ◽  
Fluid Turbulence ◽  
Radial Profiles ◽  
Parallel Dynamics ◽  
Two Machines ◽  
Probe Measurements

<!-- p, li { white-space: pre-wrap; } --><p style="text-indent: 0px; margin: 0px;">In this article we have used the 2D fluid turbulence numerical model, ESEL, to simulate turbulent transport in edge tokamak plasma. Basic plasma parameters from the ASDEX Upgrade and COMPASS tokamaks are used as input for the model, and the output is compared with experimental observations obtained by reciprocating probe measurements from the two machines. Agreements were found in radial profiles of mean plasma potential and temperature, and in a level of density fluctuations. Disagreements, however, were found in the level of plasma potential and temperature fluctuations. This implicates a need for an extension of the ESEL model from 2D to 3D to fully resolve the parallel dynamics, and the coupling from the plasma to the sheath.</p>

scholarly journals Estimation of probe measurements reliability in a supersonic flow of a four-component collisionless plasma

2021 ◽  
Vol 2021 (3) ◽  
pp. 57-69
Author(s):  
D.N. Lazuchenkov ◽  
◽  
N.M. Lazuchenkov ◽  
Keyword(s):  
Ionic Composition ◽  
Collisionless Plasma ◽  
Plasma Electron ◽  
Plasma Potential ◽  
Plasma Parameters ◽  
Probe Current ◽  
Bias Potential ◽  
Probe System ◽  
Parametric Studies ◽  
Probe Measurements

The aim of this work is to estimate the reliability of extracting the plasma electron density and temperature and ionic composition from the current-voltage (I-V) characteristic of an isolated probe system with cylindrical electrodes. An earlier proposed mathematical model of current collection by the probe system at positive bias potentials and an arbitrary ratio of the electrode areas is analyzed. The model is supplemented with a formula that determines, with an accuracy of several percent, the value of the bias potential at which the probe is under the plasma potential and the I-V characteristic splits into a transition and an electronic region. The analytical dependence of the bias potential on the plasma parameters and the ratio of the electrode areas made it possible to formalize the procedures for determining and assessing the reliability of the extracted plasma parameters using the regions of their strongest effect on the collected probe current. Parametric studies of the effect of the plasma parameters on the probe current were carried out for conditions close to measurements in the ionosphere. The paper demonstrates the feasibility of partitioning the sought-for plasma parameters into the regions of their strongest and weakest effect on the probe current in the range of the bias potentials considered. The problem of plasma parameter identification is formulated on the basis of a comparison of the probe current and the measured I-V characteristic in the L2 theoretical approximation. To each parameter there corresponds an objective function of its own, which differs in the domain of definition and the ratio of the electrode areas used in I-V characteristic measurements. Based on this formulation of the inverse problem in L2, estimates of the reliability of identification of the parameters of a plasma with two ion species are obtained depending on the errors of the model and probe measurements. The results obtained may be used in ionospheric plasma diagnostics.

scholarly journals Diagnostics of dusty plasma properties in planar magnetron sputtering device

2019 ◽  
Vol 13 (26) ◽  
pp. 64-75
Author(s):  
Qusay A. Abbas
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Discharge Current ◽  
Plasma Potential ◽  
Dust Particles ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Radial Profiles ◽  
Planar Magnetron ◽  
Radial Axis

The effect of Al dust particles on glow discharge regions, dischargevoltage, discharge current, plasma potential, floating potential,electron density and electron temperature in planar magnetronsputtering device has been studied experimentally. Four cylindricalLangmuir probes were employed to measure plasma parameters atdifferent point on the radial axis of plasma column. The resultsshows the present of Al dust causes to increase the discharge voltageand reduce the discharge current. There are two electron groups inthe present and absent of Al dust particles. The radial profiles ofplasma parameters in the present of dust are non- uniform. Thefloating potential of probe becomes more negatively while theplasma potential becomes positive when the dust immersed intoplasma region. The electron density increases in the present of dustparticle which lead to decreases the electron temperature.

Understanding core heavy impurity transport in a hybrid discharge on EAST

2021 ◽  
Author(s):  
Shengyu Shi ◽  
Jiale Chen ◽  
Clarisse Bourdelle ◽  
Xiang Jian ◽  
Tomas Odstrcil ◽  
...  
Keyword(s):  
Density Profile ◽  
Central Region ◽  
Turbulent Transport ◽  
Accumulation Process ◽  
Plasma Parameters ◽  
Toroidal Rotation ◽  
The Core ◽  
Impurity Transport ◽  
Accumulation Phase ◽  
Bulk Plasma

Abstract The behavior of heavy/high-Z impurity tungsten (W) in the core of hybrid (high normalized beta β_N plasmas) scenario on EAST with ITER-like divertor (ILD) is analyzed. W accumulation is often observed and seriously degrades the plasma performance (Xiang Gao et al 2017 Nucl. Fusion 57 056021). The dynamics of the W accumulation process of a hybrid discharge are examined considering the concurrent evolution of the background plasma parameters. It turns out that the toroidal rotation and density peaking of the bulk plasma are usually large in the central region, which is particularly prone to the W accumulation. A time slice during the W accumulation phase is modeled, accounting for both neoclassical and turbulent transport components of W, through NEO with poloidal asymmetry effects induced by toroidal rotation, and TGLF, respectively. This modeling reproduces the experimental observations of W accumulation and identifies the neoclassical inward convection/pinch velocity of W due to the large density peaking of the bulk plasma and toroidal rotation in the central region as one of the main reasons for the W accumulation. In addition, the NEO+TGLF+STRAHL modeling can not only predict the core W density profile but also closely reconstruct the radiated information mainly produced by W in the experiment.

scholarly journals Effect of the gas puff location on the divertor plasma properties in COMPASS tokamak

2020 ◽  
Vol 1492 (1) ◽  
pp. 012003
Author(s):  
M Dimitrova ◽  
M Tomes ◽  
Tsv Popov ◽  
R Dejarnac ◽  
J Stockel ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Vacuum Chamber ◽  
Plasma Potential ◽  
Saturation Current ◽  
Langmuir Probes ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Low Field ◽  
Saturation Current Density ◽  
Deuterium Gas

Abstract Langmuir probes are used to study the plasma parameters in the divertor during deuterium gas puff injection on the high- (HFS) or low-field sides (LFS). The probe data were processed to evaluate the plasma potential and the electron temperatures and densities. A difference was found in the plasma parameters depending on the gas puff location. In the case of a gas puff on the LFS, the plasma parameters changed vastly, mainly in the inner divertor – the plasma potential, the ion saturation-current density and the electron temperature dropped. After the gas puff, the electron temperature changed from 10-15 eV down to within the 5-9 eV range. As a result, the parallel heat-flux density decreased. At the same time, in the outer divertor the plasma parameters remained the same. We thus concluded that using a gas puff on the LFS will facilitate reaching a detachment regime by increasing the density of puffed neutrals. When the deuterium gas puff was on the HFS, the plasma parameters in the divertor region remained almost the same before and during the puff. The electron temperature decreased with just few eV as a result of the increased amount of gas in the vacuum chamber.

Improved Nitridation of GeO2 Interfacial layer for Ge Gate Stack Technology

2013 ◽  
Vol 1561 ◽  
Author(s):  
P. Bhatt ◽  
K. Chaudhuri ◽  
P. Maharaja ◽  
A. Nainani ◽  
M. Abraham ◽  
...  
Keyword(s):  
Interfacial Layer ◽  
Continuous Wave ◽  
Nitrogen Concentration ◽  
Plasma Potential ◽  
Lower Plasma ◽  
Gate Stack ◽  
Plasma Parameters ◽  
Plasma Analysis ◽  
Effective Power ◽  
Plasma Nitridation

ABSTRACTNitridation of GeO2 interfacial layer (IL) was done using continuous wave (CW) and pulsed wave (PW) decoupled plasma nitridation (DPN) processes. Langmuir probe analysis of the N2 plasma demonstrates that at the same effective power and pressure, PW plasma has similar electron density (Ne) with lower electron temperature (kTe) and plasma potential (Vp) as compared to CW plasma. This results in softer plasma conditions using a PW process leading to lower plasma-related damage in the IL, but without reducing the overall nitrogen concentration. The plasma parameters were further correlated to mobility (μ) and interface trap density (Dit) extracted from fabricated Ge n-MOSFETs. As expected from the plasma analysis, at the same effective power and pressure, the PW DPN process shows 1.2X higher electron mobility as compared to a CW process. This improvement can enable GeON as an IL for future Ge CMOS gate stack technology.

In-Situ Monitoring of Electrical Parameters for Dry Etching

1987 ◽  
Vol 98 ◽  
Author(s):  
J. Ignacio Ulacia F ◽  
James P. McVittie
Keyword(s):  
Plasma Potential ◽  
Circuit Model ◽  
In Situ Monitoring ◽  
Current Transport ◽  
Boltzmann Transport ◽  
Electrical Measurements ◽  
Plasma Parameters ◽  
Yield Time ◽  
The Individual ◽  
Capacitive Discharges

ABSTRACTIn this paper, external electrical measurements and a circuit model are used to obtain indirectly the plasma potential, electron density, ion current density, and sheath thickness. In a revised and extended circuit model, each element describes a current-transport mechanism. Each mechanism is described by an analytical expression in terms of previously specified plasma parameters. The model is applicable in capacitive discharges with equal-area electrodes, and it can be expanded to consider other systems. To verify its applicability, electrical measurements of voltage, current and phase angle in an SF6 : O2 discharge are used to calculate the plasma impedance. Electrical plasma measurements yield time-averaged values for the impedance; the values obtained for each device reflect this dependency. After the calculation of each electrical device, SPICE 3.7a simulations separated the individual contribution of current transport by each mechanisms and validated the assumptions. The plasma parameters obtained by this technique agree well with a Langmuir-probe measurement, solutions of the Boltzmann transport equation, and data published in the literature.

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