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Modification of plasma flows with gas puff in the scrape-off layer of ADITYA tokamak
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10.1063/1.4811476
/content/aip/journal/pop/20/6/10.1063/1.4811476
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/6/10.1063/1.4811476
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Projections of probe heads and the gas puff valve on one poloidal/azimuthal plane.

Image of FIG. 2.
FIG. 2.

(a) Schematic diagram of the probe head configuration, including pin probes and plate probes that are used for Mach number measurement. Probes 1, 2, and 3 are used for ion saturation current and 4, 5, and 7 are used for floating potential measurements. (b) Locations of the top probe, the radial probe and the gas puff valve with respect to the limiter. Directions of plasma current and toroidal magnetic field are also indicated.

Image of FIG. 3.
FIG. 3.

Examples of typical ADITYA discharge: (a) chord-averaged plasma density measured by W interferometer and voltage pulses on the gas-puff valve, (b) loop voltage, (c) plasma current, (d) radiated power along edge and core chords as measured by AXUV bolometer camera, (e) shows , C-III and voltage on the gas-puff valve during 40–65 ms into the discharge, (f) floating potential, (g) ion saturation current at probe pins (see Fig. 2 ) and (h) soft X-ray signal. The sharp dip in soft X-ray signal is may be ignored as pick up, and hence the soft X-ray signal increases during the gas puff.

Image of FIG. 4.
FIG. 4.

Radial profiles of (a) edge plasma density, (b) electron temperature, (c) floating potential, and (d) . The vertical shadow bands indicate separation of long connection length SOL from the short connection length SOL (limiter shadow) region. The dashed lines in Figs. 4(a) and 4(b) are the eye-fits. The errorbars on and represent 2σ (standard deviation) errors on their mean values, and those on represent 1σ errors.

Image of FIG. 5.
FIG. 5.

(a) Effect of gas puff on electron temperature measured by the triple probe; the maximum reduction in electron temperature is observed about 1.5 ms after the end of the voltage pulse on the gas puff valve, (b) the ratio of electron temperature during and before the gas-puff, , as a function of the duration of temperature reduction.

Image of FIG. 6.
FIG. 6.

Effect of gas puff on fluctuation of (a) ion saturation current and (b) floating potential. The fluctuation in ion saturation current is normalized but potential fluctuation is shown in the form of its rms value. The vertical shadow bands indicate separation of long connection length SOL from the short connection length SOL (limiter shadow) region.

Image of FIG. 7.
FIG. 7.

Radial profiles of (a) particle flux, , (b) toroidal Mach number M, and (c) variation of with M. The vertical shadow bands indicate separation of long connection length SOL from the short connection length SOL (limiter shadow) region. The dashed lines in Figs. 7(a) and 7(b) areeye-fits. The errorbars on represent 1σ errors and those on represent 8σ errors. The error in M is calculated by using the formula, , where and are errors in the upstream and downstream current density, respectively.

Image of FIG. 8.
FIG. 8.

(a) Ion saturation current on upstream and downstream probes before and during gas puff, after 2 ms smoothing, (b) Mach numbers measured before (M) and during gas-puff (M) in several discharges. The error bar indicates the scatter in the data.

Image of FIG. 9.
FIG. 9.

(a) Parallel Mach number measured at three poloidal locations and just behind the limiter, (b) slab model of the SOL showing probe positions and measured flow directions. The probe locations are shown by “T,” “R,” and “O” indicating Mach probes at the top, radial, and outboard mid-plane, respectively, “GP” indicates the location of gas puff valve. The solid and dashed arrows show the flow directions before/without and during gas puff. The dotted lines at the “GP” location indicate the flow directions because of local ionization source by gas puff.

Image of FIG. 10.
FIG. 10.

Radial profiles of (a) and (b) . The errorbars represent 8σ errors in the figure. The vertical shadow bands indicate separation of long connection length SOL from the short connection length SOL (limiter shadow) regions. The dashed lines show the eye-fits.

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/content/aip/journal/pop/20/6/10.1063/1.4811476
2013-06-20
2014-04-19
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Modification of plasma flows with gas puff in the scrape-off layer of ADITYA tokamak
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/6/10.1063/1.4811476
10.1063/1.4811476
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