Radial structure of electron drift waves and anomalous transport in the edge plasma

1999 ◽  
Vol 77 (2) ◽  
pp. 113-126
Author(s):  
J LV Lewandowski
Keyword(s):  
Edge Plasma ◽  
Tokamak Plasma ◽  
Medium Size ◽  
Drift Waves ◽  
Electron Drift ◽  
Plasma Parameters ◽  
Mode Amplitude ◽  
Radial Structure ◽  
Density Scale ◽  
Toroidal Geometry

The radial structure of electron drift waves in a low-pressure tokamak plasma is presented. The ions are cold and an electrostatic approximation for the fluctuating potential is used. It is shown that the problem of the radial structure of drift waves in toroidal geometry is amenable to a two-step solution; in first approximation, the radial structure of the mode is neglected and the problem to be solved is the usual eigenmode equation along the (extended) poloidal angle; in second approximation, the mode amplitude is expanded in ascending powers of the parameter (k⊥Ln)-1/2 , where k⊥ is the magnitude of the lowest-order wavevector and Ln is the radial density scale length. It is shown that the radial structure of drift-type modes can depend strongly on the magnetic shear and the scalar magnetic curvature. Numerical calculations for plasma parameters relevant to the edge region of medium-size tokamaks are presented. PACS Nos.: 52.35Kt, 52.30Jb, and 52.35Ra

scholarly journals Radial Structure of Electron Drift Waves in Tokamak Geometry

1999 ◽  
Vol 52 (1) ◽  
pp. 59
Author(s):  
J. L. V. Lewandowski
Keyword(s):  
Low Pressure ◽  
Tokamak Plasma ◽  
Drift Waves ◽  
Electron Drift ◽  
Radial Density ◽  
Mode Amplitude ◽  
First Approximation ◽  
Field Diffusion ◽  
Radial Structure ◽  
Toroidal Geometry

The radial structure of electron drift waves in a low-pressure tokamak plasma is presented. The ions are cold and an electrostatic approximation for the fluctuating potential is used. It is shown that problem of the radial structure of drift waves in toroidal geometry is amenable to a two-step solution; in the first approximation, the radial structure of the mode is neglected and the problem to be solved is the usual eigenmode equation along the (extended) poloidal angle; in the second approximation, the mode amplitude is expanded in ascending powers of the parameter (k⊥Ln)–1/2, where k⊥ is the magnitude of the lowest-order wavevector and Ln is the radial density scalelength. The implications of these radially-extended drift-type modes for the anomalous cross-field diffusion are discussed.

Erratum: Radial structure of electron drift waves and anomalous transport in the edge plasma

1999 ◽  
Vol 77 (5) ◽  
pp. 409-409
Author(s):  
J LV Lewandowski
Keyword(s):  
Anomalous Transport ◽  
Edge Plasma ◽  
Drift Waves ◽  
Electron Drift ◽  
Radial Structure

Electron drift waves in an advanced tokamak plasma

2006 ◽  
Vol 73 (6) ◽  
pp. 648-654
Author(s):  
M A Mahmood ◽  
T Rafiq ◽  
M Persson
Keyword(s):  
Tokamak Plasma ◽  
Drift Waves ◽  
Electron Drift

scholarly journals Diamond-Coated Plasma Probes for Hot and Hazardous Plasmas

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4524
Author(s):  
Codrina Ionita ◽  
Roman Schrittwieser ◽  
Guosheng Xu ◽  
Ning Yan ◽  
Huiqian Wang ◽  
...  
Keyword(s):  
Edge Plasma ◽  
Diagnostic Tools ◽  
Medium Size ◽  
Plasma Parameters ◽  
Republic Of China ◽  
Nano Crystalline ◽  
Laboratory Plasmas ◽  
Probe Material ◽  
Harmful Effects ◽  
Subsequent Risk

Plasma probes are simple and inexpensive diagnostic tools for fast measurements of relevant plasma parameters. While in earlier times being employed mainly in relatively cold laboratory plasmas, plasma probes are now routinely used even in toroidal magnetic fusion experiments, albeit only in the edge region, i.e., the so-called scrape-off layer (SOL), where temperature and density of the plasma are lower. To further avoid overheating and other damages, in medium-size tokamak (MST) probes are inserted only momentarily by probe manipulators, with usually no more than a 0.1 s per insertion during an average MST discharge of a few seconds. However, in such hot and high-density plasmas, their usage is limited due to the strong particle fluxes onto the probes and their casing which can damage the probes by sputtering and heating and by possible chemical reactions between plasma particles and the probe material. In an attempt to make probes more resilient against these detrimental effects, we tested two graphite probe heads (i.e., probe casings with probes inserted) coated with a layer of electrically isolating ultra-nano-crystalline diamond (UNCD) in the edge plasma region of the Experimental Advanced Superconducting Tokamak (EAST) in Hefei, People’s Republic of China. The probe heads, equipped with various graphite probe pins, were inserted frequently even into the deep SOL up to a distance of 15 mm inside the last closed flux surface (LCFS) in low- and high-confinement regimes (L-mode and H-mode). Here, we concentrate on results most relevant for the ability to protect the graphite probe casings by UNCD against harmful effects from the plasma. We found that the UNCD coating also prevented almost completely the sputtering of graphite from the probe casings and thereby the subsequent risk of re-deposition on the boron nitride isolations between probe pins and probe casings by a layer of conductive graphite. After numerous insertions into the SOL, first signs of detachment of the UNCD layer were noticed.

scholarly journals Modelling of lithium transport and its influence on the edge plasma parameters in T-15MD tokamak

2017 ◽  
Vol 941 ◽  
pp. 012025
Author(s):  
A A Pshenov ◽  
A S Kukushkin
Keyword(s):  
Edge Plasma ◽  
Plasma Parameters ◽  
Lithium Transport

Electron drift caused by rf field gradient creates many plasma phenomena: An attempt to distinguish the cause and the effect

2011 ◽  
Vol 78 (2) ◽  
pp. 165-174 ◽  
Author(s):  
C. L. XAPLANTERIS ◽  
E. D. FILIPPAKI ◽  
I. S. MISTAKIDIS ◽  
L. C. XAPLANTERIS
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Low Temperature ◽  
Mathematical Models ◽  
Field Gradient ◽  
Collision Frequency ◽  
The Other ◽  
Frequency Effect ◽  
Electron Drift ◽  
Plasma Parameters

AbstractMany experimental data along with their theoretical interpretations on the rf low-temperature cylindrical plasma have been issued until today. Our Laboratory has contributed to that research by publishing results and interpretative mathematical models. With the present paper, two issues are being examined; firstly, the estimation of electron drift caused by the rf field gradient, which is the initial reason for the plasma behaviour, and secondly, many new experimental results, especially the electron-neutral collision frequency effect on the other plasma parameters and quantities. Up till now, only the plasma steady state was taken into consideration when a theoretical elaboration was carried out, regardless of the cause and the effect. This indicates the plasma's complicated and chaotic configuration and the need to simplify the problem. In the present work, a classification about the causality of the phenomena is attempted; the rf field gradient electron drift is proved to be the initial cause.

The role of edge plasma parameters in H-mode density limit on the JET-ILW

2021 ◽  
Vol 61 (6) ◽  
pp. 066009
Author(s):  
H.J. Sun ◽  
R.J. Goldston ◽  
A. Huber ◽  
X.Q. Xu ◽  
J. Flanagan ◽  
...  
Keyword(s):  
Edge Plasma ◽  
Plasma Parameters ◽  
Density Limit

Scaling study of edge plasma parameters using a multi-device database

1995 ◽  
Vol 220-222 ◽  
pp. 672-676 ◽  
Author(s):  
H.Y.W. Tsui ◽  
W.H. Miner ◽  
A.J. Wootton
Keyword(s):  
Edge Plasma ◽  
Plasma Parameters

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>

Collisionless drift waves in the H mode edge (plasma)

1994 ◽  
Vol 34 (1) ◽  
pp. 87-91 ◽  
Author(s):  
S Sen ◽  
M.G Rusbridge ◽  
R.J Hastie
Keyword(s):  
Edge Plasma ◽  
Drift Waves
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