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Fluctuations and intermittent poloidal transport in a simple toroidal plasma
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10.1063/1.4816947
/content/aip/journal/pop/20/7/10.1063/1.4816947
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/7/10.1063/1.4816947

Figures

Image of FIG. 1.
FIG. 1.

A schematic view of cross-section of BETA and diagnostics. Schematic discharge circuit is also shown. All the probe measurements are done close to the plane of the limiter and in the horizontal plane z = 0. The radial position indicated by in the rest of the plots is with respect to the minor axis. The toroidal field coils are not shown here. The negative corresponds to HFS.

Image of FIG. 2.
FIG. 2.

The fluctuation driven poloidal flux is shown for three values of magnetic field. The HFS values are relatively smaller. Measurements close to the minor axis are not shown here because of possible erroneous estimation due to limited spatial resolution of the probe. Reprinted with permission from T. S. Goud , Phys. Plasmas , 032307 (2012). Copyright (2012) American Institute of Physics.

Image of FIG. 3.
FIG. 3.

Time series plots for from the measurements at . The actual data records spread from 0 to ; however, a blow up of only is shown here for a better view of the flux events.

Image of FIG. 4.
FIG. 4.

PDF of fluctuation induced poloidal flux for . Distributions at different radial locations on LFS are shown. The time averaged flux is found to be maximum at .

Image of FIG. 5.
FIG. 5.

PDF of fluctuation induced poloidal flux for . Distributions at different radial locations on HFS are shown. The time averaged flux on HFS is usually found to be small compared to LFS.

Image of FIG. 6.
FIG. 6.

A comparison of the experimental PDFs for at with Gaussian distributions of similar mean and standard deviation for .

Image of FIG. 7.
FIG. 7.

Time series plots for fluctuations in density and poloidal velocity at , for . The actual data records spread from 0 to ; however, a blow up of only is shown here to indicate the fluctuation trend.

Image of FIG. 8.
FIG. 8.

PDF plots for fluctuations in density (first column), poloidal velocity (second column), and (third column) at for three values of . A comparison of the experimental PDFs (solid line) with Gaussian distribution of similar standard deviation (dashed line) is also shown.

Image of FIG. 9.
FIG. 9.

PDF plots for fluctuations in density (first column), poloidal velocity (second column), and (third column) at for three values of . A comparison of the experimental PDFs (solid line) with Gaussian distribution of similar standard deviation (dashed line) is also shown.

Image of FIG. 10.
FIG. 10.

Radial profile of skewness for , for three values of . For a Gaussian distribution,  = 0 (dotted line). To observe the relative spread in the skewness, it is estimated from multiple discharges at each location.

Image of FIG. 11.
FIG. 11.

Radial profile of kurtosis for , for three values of . For a Gaussian distribution,  = 3 (dotted line). To observe the relative spread in the kurtosis, it is estimated from multiple discharges at each location.

Image of FIG. 12.
FIG. 12.

Radial profile of skewness for , for three values of . For a Gaussian distribution,  = 0 (dotted line). Values of in the region are not estimated due to poor spatial resolution of the probe in this region.

Image of FIG. 13.
FIG. 13.

Radial profile of kurtosis for , for three values of . For a Gaussian distribution  = 3 (dotted line). Values of in the region are not estimated due to poor spatial resolution of the probe in this region.

Image of FIG. 14.
FIG. 14.

A plot quantifying the contribution from large flux events to the net fluctuation induced poloidal flux using Eq. (2) at , for . The intercept on the vertical axis indicates .

Image of FIG. 15.
FIG. 15.

A plot of cumulative probability versus cumulative flux fraction for , at . The intercept on the horizontal line with cumulative probability equal to 1 indicates . The advantage of this plot is that it is easy to visualize the fraction of flux events (starting from the highest flux value) and corresponding flux contribution.

Image of FIG. 16.
FIG. 16.

A comparison of the experimental PDF for at with the data points estimated theoretically using Eq. (3) .

Image of FIG. 17.
FIG. 17.

A comparison of the experimental PDFs (solid line) for at with the data points estimated theoretically using Eq. (3) . The comparison is done for three values.

Tables

Generic image for table
Table I.

A tabular summary of and values for various quantities at .

Generic image for table
Table II.

A tabular summary of and values for various quantities at .

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/content/aip/journal/pop/20/7/10.1063/1.4816947
2013-07-30
2014-04-25
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Fluctuations and intermittent poloidal transport in a simple toroidal plasma
http://aip.metastore.ingenta.com/content/aip/journal/pop/20/7/10.1063/1.4816947
10.1063/1.4816947
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