Analysis of the radial and poloidal turbulent transport in the edge tokamak plasma

2013 ◽  
Vol 79 (5) ◽  
pp. 647-655 ◽  
Author(s):  
S. MESHKANI ◽  
M. GHORANNEVISS ◽  
M. LAFOUTI ◽  
A. SALAR ELAHI
Keyword(s):  
Magnetic Field ◽  
Turbulent Transport ◽  
Edge Plasma ◽  
Tokamak Plasma ◽  
Spectral Features ◽  
Negative Bias ◽  
Langmuir Probes ◽  
Negative Bias Voltage ◽  
Helical Magnetic Field ◽  
Transport Method

AbstractIn this paper, turbulent transport in the edge plasma of the IR-T1 tokamak (r/a = 0.9) in the presence of a resonant helical magnetic field (RHF) and a biased limiter has been investigated and analyzed. The time evolution of potential fluctuation, and electric field and turbulent transport have been measured by using two arrays of the Langmuir probes in both the radial and poloidal directions. The experiments have been done in different regimes such as limiter biasing and RHF, and both of them. The analyses have been done by the fast Fourier transport method and their spectral features are obtained with the help of the standard autocorrelation technique. The results show that radial turbulent transport decreases about 60% after positive biasing application, while it increases about 40% after negative biasing. The effect of positive biasing on poloidal turbulent transport displays an increase of about 55%, while the negative bias voltage decreases the poloidal turbulent transport about 30%. Consequently, confinement is improved and plasma density rises significantly due to the applied positive biasing in IR-T1. However, the results are reversed when negative biasing is applied. Also, in this work, the results of the applied RHF (L = 3) are compared with biasing results and analyzed.

Approaching to the ideal condition of plasma confinement by applying external resonant fields in IR-T1 tokamak

2015 ◽  
Vol 81 (3) ◽  
Author(s):  
Sakineh Meshkani ◽  
Mahmood Ghoranneviss ◽  
Mansoureh Lafouti
Keyword(s):  
Magnetic Field ◽  
Turbulent Transport ◽  
Edge Plasma ◽  
Ideal Condition ◽  
Plasma Confinement ◽  
Applied Bias ◽  
Inverse Results ◽  
Electric And Magnetic Field ◽  
Helical Magnetic Field ◽  
The Ideal

For understanding the effect of resonant helical magnetic field (RHF) and bias on the edge plasma turbulent transport, the radial and poloidal electric field (Er, EP), poloidal and toroidal magnetic field (BP, Br) were detected by the Langmuir probe, magnetic probe and diamagnetic loop. The poloidal, toroidal and radial velocity (VP, Vr, Vt) can be determined from the electric and magnetic field. In the present work, we have investigated the effect of the magnitude of bias (Vbias = 200v, Vbias = 320v) on Er, EP, BP, Bt, VP, Vr, Vt. Moreover, we applied RHF with L = 2, L = 3 and L = 2 and 3 and investigate the effect of the helical windings radius on above parameters. Also, the experiment was repeated by applying the positive biasing potentials and RHF's simultaneously. The results show that by applying bias to the plasma at t = 15 msec at r/a = 0.9, Er, BP and Bt increase while EP decreases. The best modification occurs at Vbias = 200v. By applying RHF to the plasma, both the electric and magnetic field vary. Er reaches the highest in the presence of RHF with L = 3. The same results are obtained for BP, Bt, VP and Vt. While the inverse results are obtained for EP and Vr. Finally, RHF and bias are applied simultaneously to the plasma. With applied bias with Vbias = 200v and RHF with L = 2 and 3, we reach to the ideal circumstance. The same results obtain in the situation with Vbias = 320v and RHF with L = 2 and 3.

scholarly journals The dynamic ergodic divertor in the TEXTOR tokamak: plasma response to dynamic helical magnetic field perturbations

2004 ◽  
Vol 46 (12B) ◽  
pp. B143-B155 ◽  
Author(s):  
K H Finken ◽  
S S Abdullaev ◽  
W Biel ◽  
M F M de Bock ◽  
C Busch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Tokamak Plasma ◽  
Plasma Response ◽  
Helical Magnetic Field

Modification of tokamak edge plasma turbulence and transport by biasing and resonant helical magnetic field

2013 ◽  
Vol 84 (5) ◽  
pp. 053504 ◽  
Author(s):  
Mansoureh Lafouti ◽  
Mahmood Ghoranneviss ◽  
Sakineh Meshkani ◽  
Ahmad Salar Elahi
Keyword(s):  
Magnetic Field ◽  
Plasma Turbulence ◽  
Edge Plasma ◽  
Tokamak Edge ◽  
Helical Magnetic Field

EXPERIMENTAL INVESTIGATION OF LANGMUIR PROBES

1967 ◽  
Vol 45 (10) ◽  
pp. 3199-3209 ◽  
Author(s):  
R. M. Clements ◽  
H. M. Skarsgard
Keyword(s):  
Magnetic Field ◽  
Microwave Radiometer ◽  
Resonant Cavity ◽  
Boltzmann Distribution ◽  
Probable Error ◽  
Langmuir Probes ◽  
Noticeable Effect ◽  
Probe Field ◽  
Probe Radius ◽  
Weakly Ionized

Electron temperatures and densities measured in a weakly ionized helium afterglow with cylindrical double probes are compared with measurements obtained using a gated microwave radiometer and a microwave resonant cavity. The pressure was varied from 0.1 to 8.5 Torr. At low pressure, magnetic fields up to 0.11 T were applied. Independent of the values of the electron Larmor radii or particle mean free paths relative to the probe radius, the probes correctly measured the electron temperatures within an estimated random probable error of ±4% and a systematic error not exceeding ±4%. This demonstrates the validity, for the range of conditions studied, of a fundamental assumption of probe theory—that electrons in a retarding probe field are in a Maxwell–Boltzmann distribution at a temperature unaffected by the presence of the probe. Towards higher pressure the measurements show an increasing depression of the plasma density near the probe, associated with the diffusion to it. The applied magnetic field had no noticeable effect on the densities measured with the probes as compared with the cavity measurements.

scholarly journals A Helical Magnetic Field in the Jet of 3C 273

2002 ◽  
Vol 54 (3) ◽  
pp. L39-L43 ◽  
Author(s):  
Keiichi Asada ◽  
Makoto Inoue ◽  
Yutaka Uchida ◽  
Seiji Kameno ◽  
Kenta Fujisawa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Helical Magnetic Field

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>

A Surprising Result: “Bulk” SiC Defects in the Negative Bias Instability in 4H-SiC MOSFETs

2016 ◽  
Vol 858 ◽  
pp. 513-517 ◽  
Author(s):  
Mark A. Anders ◽  
Patrick M. Lenahan ◽  
Aivars J. Lelis
Keyword(s):  
Magnetic Field ◽  
Elevated Temperature ◽  
Negative Bias ◽  
Surprising Result ◽  
Zero Crossing ◽  
Electrically Detected Magnetic Resonance ◽  
G Value ◽  
Bias Temperature Stress ◽  
Bias Instability ◽  
The Magnetic Field

We utilize electrically detected magnetic resonance and “on-the-fly” elevated temperature stressing to examine the effects of negative bias temperature stress on defects within the “bulk” SiC, that is, below the SiC/SiO2 interface. We observe generation of two temperature-dependent defects; one has a two (or three) line spectrum with lines separated by about 61 (30) Gauss when the SiC/SiO2 interface is perpendicular to the magnetic field and very slightly less, about 59 (30) Gauss when the SiC/SiO2 interface is parallel to the field. The second spectrum has a single line with zero-crossing g = 2.0118 when the magnetic field is nearly perpendicular to the SiC/SiO2 interface; the g-value drops to about 2.0016 with the field parallel to the SiC/SiO2 interface. We also observe strong evidence for hydrogen motion within the “bulk” SiC, as both spectra broaden significantly at elevated temperature, with broadening at both high and low fields and frequencies.

scholarly journals Particle Dynamics in the RMP Ergodic Layer under the Influence of Edge Plasma Turbulence

10.14311/1831 ◽  
2013 ◽  
Vol 53 (4) ◽  
Author(s):  
Matúš Kurian ◽  
Ladislav Krlín ◽  
Pavel Cahyna ◽  
Radomír Pánek
Keyword(s):  
Plasma Turbulence ◽  
Edge Plasma ◽  
Tokamak Plasma ◽  
Edge Region ◽  
Ion Dynamics ◽  
Plasma Dynamics ◽  
Complex Processes ◽  
Edge Localized Modes ◽  
Particle Simulations ◽  
Practical Implications

The complex processes in edge tokamak plasma are affected (among others) both by resonant magnetic perturbation (RMP) and by plasma turbulence. RMP is nowadays considered to be a candidate for the mitigation of the edge-localized modes (ELMs). The effect of plasma turbulence inthe edge region has not been studied yet. Since both RMP and plasma turbulence should influence plasma dynamics, studies of their simultaneous effect have potential practical implications. Using a simplified model of the turbulence and single-particle simulations, we discovered that its effect at realistic amplitudes changes the ion dynamics significantly. We expect that the turbulence has a similar effect on electrons, thus potentially influencing the ELM mitigation mechanism.

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