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Characterization of core and edge turbulence in - and enhanced -mode Alcator C-Mod plasmas
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10.1063/1.1899161
/content/aip/journal/pop/12/5/10.1063/1.1899161
http://aip.metastore.ingenta.com/content/aip/journal/pop/12/5/10.1063/1.1899161
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Discharge overview for shot 104 03 10 007 from top to bottom: Stored energy, line integrated density, ICRF power, and light vs time. The vertical dashed line marks the transition from to EDA mode.

Image of FIG. 2.
FIG. 2.

Discharge overview for shot 104 03 10 021 from top to bottom: Stored energy, line integrated density, ICRF power, and light vs time. The dotted trace in the bottom plot shows the neutron rate in arbitrary units. The vertical dashed line marks the transition from EDA to mode studied.

Image of FIG. 3.
FIG. 3.

(Color). Machine outline and equilibrium fit (EFIT) flux surfaces for shot 104 03 10 007 at 0.74 s. The diagnostic lines-of-sight are shown in red: The vertical lines are the PCI chords, the two lines meeting at are the reflectometer viewing geometries, the square is the position of the poloidal magnetic field measurement, and the cone expanding towards the inner wall is the -light diode view.

Image of FIG. 4.
FIG. 4.

The 2 ms time window where the 15 kHz sound burst is detected by the 32 PCI channels. The vertical markers are displaced using the sound speed, : Propagation towards channel 1 from channel 32 is clearly visible. The signal in channel 7 is small due to an electronics fault inside the detector.

Image of FIG. 5.
FIG. 5.

(Color). Two-dimensional Fourier transform spectra of the 15 kHz PCI sound-burst signals shown in Fig. 4, 1 kHz frequency resolution. A peak is observed at (and 15 kHz) corresponding to the sound wave and a line from (and 0 kHz) to that peak corresponds to the sound speed.

Image of FIG. 6.
FIG. 6.

(Color). Main plot: Spectrogram of a core PCI channel (17) vs time. The color scale is logarithmic, time resolution is 1 ms, and frequency resolution is 5 kHz. The vertical dashed line marks the transition from to EDA mode. Bottom plot: Traces of stored energy (black), ICRF power (red), and light (blue).

Image of FIG. 7.
FIG. 7.

Left: Autopower spectra of a PCI core channel (17) in mode (solid line) and EDA mode (dotted line). Right: Same spectra as in the left-hand plot, but the frequency scale of the -mode spectrum has been multiplied by a factor of two. The spectra are averaged over 10 ms and shown with a 5 kHz frequency resolution. The small spikes at 750 kHz and 3.3 MHz are due to electronic pickup.

Image of FIG. 8.
FIG. 8.

-mode scaling factor vs time; the time resolution is 10 ms. Diamonds are -mode points, triangles are EDA -mode points. The vertical dashed line marks the transition from to EDA mode.

Image of FIG. 9.
FIG. 9.

(Color). Two-dimensional Fourier transform spectra of mode (left-hand plot) and EDA mode (right-hand plot). The spectra are averaged over 10 ms and shown with a 5 kHz frequency resolution.

Image of FIG. 10.
FIG. 10.

Left: Autopower spectra at for mode (solid line) and EDA mode (dotted line). Right: Same spectra as in the left-hand plot, but the frequency scale of the -mode spectrum has been multiplied by a factor of two. The spectra are averaged over 10 ms and shown with a 5 kHz frequency resolution.

Image of FIG. 11.
FIG. 11.

Wave-number spectra for mode (diamonds) and EDA mode (triangles). The spectra are integrated from 20 kHz to 2 MHz and averaged over 10 ms.

Image of FIG. 12.
FIG. 12.

(Color). Tracking of the dominant QC-mode wave number and frequency vs time. In the top plot we display the frequency where the two-dimensional Fourier transform spectra have a maximum in the frequency interval shown. The frequency resolution is 5 kHz, time resolution 1 ms. In the second plot from the top we show the corresponding . For the two top plots, the red (black) traces are for negative (positive) . The third plot from the top shows the core toroidal velocity and the bottom plot shows wave forms of stored energy (black), ICRF power (red), and light (blue). The vertical dashed line marks the transition from to EDA mode.

Image of FIG. 13.
FIG. 13.

Flux surface angle vs for shot 104 03 10 007 at and 0.9 s. The vertical dashed line indicates the LCFS and the diamond marks a point beyond the bottom of the plasma, .

Image of FIG. 14.
FIG. 14.

(Color). Left: Cross correlation between light and density fluctuation band powers from PCI (channel 17) vs band central frequency and (units of 0.5 ms). Right: Cross correlation between the poloidal magnetic field and density fluctuation band powers from PCI vs band central frequency and (units of 0.5 ms). The cross correlations in both plots are calculated using a 100 ms time window centered on the transition from to EDA mode.

Image of FIG. 15.
FIG. 15.

(Color). Cross correlation between temperatures and density fluctuation band power from PCI (channel 17, integrated from 20 kHz to 2 MHz) vs the position of the temperature measurements and (units of 0.5 ms). The vertical line shows the position of the LCFS from EFIT. The cross correlations are calculated using a 100 ms time window centered on the transition from to EDA mode.

Image of FIG. 16.
FIG. 16.

Thomson scattering density profiles in mode (diamonds) and EDA mode (triangles). The two vertical lines indicate the magnetic axis (left) and the LCFS (right) from EFIT. The cutoff density for the 132 GHz reflectometer channel is shown as a dashed horizontal line.

Image of FIG. 17.
FIG. 17.

(Color). Bremsstrahlung profiles covering 25 ms at the transition from EDA to mode. The profiles are colorcoded so that red is the first time slice (EDA mode) and black the last ( mode). The two vertical lines indicate the magnetic axis (left) and the LCFS (right) from EFIT.

Image of FIG. 18.
FIG. 18.

(Color). Main plot: Spectrogram of the 132 GHz reflectometer channel vs time. The color scale is logarithmic, time resolution is 1 ms, and frequency resolution is 5 kHz. The vertical dashed line marks the transition from EDA to mode studied. Bottom plot: Traces of stored energy (black), ICRF power (red), and light (blue).

Image of FIG. 19.
FIG. 19.

(Color). Left: Cross correlation between light and density fluctuation band powers from the 132 GHz reflectometer channel vs band central frequency and (units of 0.5 ms). Right: Cross correlation between the poloidal magnetic field and density fluctuation band powers from the 132 GHz reflectometer channel vs band central frequency and (units of 0.5 ms). The cross correlations are calculated using a 20 ms time window centered on the transition from EDA to mode.

Image of FIG. 20.
FIG. 20.

(Color). Cross correlation between PCI band powers integrated from 20 kHz to 2 MHz and the amplitude of the 132 GHz reflectometer channel vs the major radius of the PCI chords and (units of 0.5 ms). The vertical line shows the position of the magnetic axis from EFIT. The reflectometer signal has been high pass filtered at 20 kHz. The cross correlations are calculated using a 20 ms time window centered on the transition from EDA to mode. The correlation for channel 7 was left out due to an electronics fault inside the detector.

Image of FIG. 21.
FIG. 21.

Left: Band power of a core PCI channel (17) vs time for shot 104 03 10 007. The band power has been normalized by the line integrated density squared. The frequency range is [20 kHz, 2 MHz] and the time resolution is 1 ms. The vertical dashed line marks the transition from to EDA mode. Right: Band power of the 132 GHz reflectometer channel vs time for shot 104 03 10 021. The frequency range is [20 kHz, 500 kHz] and the time resolution is 1 ms. The vertical dashed line marks the transition from EDA - to -mode studied.

Image of FIG. 22.
FIG. 22.

(Color). Left: Thomson scattering density profiles in mode (black diamonds) and EDA mode (red triangles). The two vertical lines indicate the magnetic axis (left) and the LCFS (right) from EFIT. The cutoff densities for the 88 and 132 GHz reflectometer channels are shown as dashed horizontal lines. Right: The main plot shows the spectrogram of the 88 GHz reflectometer channel vs time. The colorscale is logarithmic, time resolution 1 ms and frequency resolution 5 kHz. The vertical dashed line marks the transition from to EDA mode studied. The bottom plot displays traces of stored energy (black), ICRF power (red), and light (blue).

Image of FIG. 23.
FIG. 23.

Pitch angle vs for shot 104 03 10 007 at and 0.9 s. The vertical dashed line indicates the LCFS and the diamond marks a point beyond the bottom of the plasma, .

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/content/aip/journal/pop/12/5/10.1063/1.1899161
2005-05-05
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Characterization of core and edge turbulence in L- and enhanced DαH-mode Alcator C-Mod plasmas
http://aip.metastore.ingenta.com/content/aip/journal/pop/12/5/10.1063/1.1899161
10.1063/1.1899161
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