1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
The effect of off-axis neutral beam injection on sawtooth stability in ASDEX Upgrade and Mega-Ampere Spherical Tokamak
Rent:
Rent this article for
USD
10.1063/1.3187905
/content/aip/journal/pop/16/7/10.1063/1.3187905
http://aip.metastore.ingenta.com/content/aip/journal/pop/16/7/10.1063/1.3187905
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

The beam trajectories of the off-axis PINI in ASDEX Upgrade as the PINI is tilted on its support. Also shown for comparison is the approximate position of the surface.

Image of FIG. 2.
FIG. 2.

The soft x-ray emission in the three ASDEX Upgrade plasmas. The sawtooth period decreases as the beam is injected further off-axis. Discharge 24 006 represents the most on-axis NBI heating and shot 24 007 is the most off-axis.

Image of FIG. 3.
FIG. 3.

The last-closed flux surface and the surface for two MAST discharges, one at and one at , shown with respect to the approximate NBI shadow.

Image of FIG. 4.
FIG. 4.

The sawtooth period with respect to the vertical height of the magnetic axis in MAST plasmas with , , . The light gray (red online) and dark gray (blue online) points correspond to the plasma cross sections shown in Fig. 3 .

Image of FIG. 5.
FIG. 5.

The sawtooth period with respect to the vertical height of the magnetic axis in MAST plasmas with , , and .

Image of FIG. 6.
FIG. 6.

The toroidal rotation frequency in MAST discharges 20 604 , 20 603 , 20 601 , and 20 610 . Also shown is the position of the surface in each case (vertical solid lines).

Image of FIG. 7.
FIG. 7.

The current density profile for ASDEX Upgrade discharge 24 007 with respect to as calculated by . The neutral beam driven current is very broad and small compared to the plasma current (here magnified by an order of magnitude for clarity). The current density profiles before the off-axis PINI is applied (2.9 s) and after (3.1 s) are approximately the same.

Image of FIG. 8.
FIG. 8.

The fast ion density from ASDEX Upgrade discharge 24 007 at (averaged over 0.4 s) calculated by shown in the poloidal cross section. The fast ions from the on-axis PINI have higher density than the off-axis ions, and so dominate this plot, even though the off-axis passing ions have a strong effect on mode stability.

Image of FIG. 9.
FIG. 9.

The fast ion distribution function with respect to for ASDEX Upgrade discharges 24 005, 24 006, and 24 007, as calculated by . The inversion radii found from the soft x-ray emission are shown for comparison.

Image of FIG. 10.
FIG. 10.

The current density profile for MAST discharge 21 041 as a function of . The neutral beam driven current predicted by is also shown, and found to be very broad and unlikely to significantly change the magnetic shear at the surface.

Image of FIG. 11.
FIG. 11.

The -profiles in MAST discharges 21 040 and 21 041 as measured by the MSE diagnostic. The tick mark illustrates the position of the inversion radius from the soft x-ray emission.

Image of FIG. 12.
FIG. 12.

Beam fast ion distribution functions at 300 ms in MAST discharges 21 040 and 21 041 as calculated by . It is clear that the more vertically displaced plasma in shot 21 041 leads to a more off-axis fast ion population.

Image of FIG. 13.
FIG. 13.

The fast ion distribution function with respect to for MAST discharges 21 040 and 21 041, as calculated by . The location from the sawtooth inversion radius is shown for comparison.

Image of FIG. 14.
FIG. 14.

The change in the potential energy of the internal kink mode due to the presence of energetic passing ions in ASDEX Upgrade shots 24 005, 24 006, and 24 007 as calculated by the code. As the deposition location is moved further outside , the passing particles become more destabilizing. This is in qualitative agreement with the sawtooth period, also shown for comparison.

Image of FIG. 15.
FIG. 15.

The change in the potential energy of the internal kink mode due to the presence of energetic passing ions in MAST shots 21 040 , 20 602 , and 21 041 as calculated by the code. As the deposition location is moved further outside , the passing particles become more destabilizing. The increased trapped fraction results in enhanced trapped ion stabilization which is approximately balanced by increased instability drive due to reduction in elongation and triangularity.

Loading

Article metrics loading...

/content/aip/journal/pop/16/7/10.1063/1.3187905
2009-07-27
2014-04-23
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: The effect of off-axis neutral beam injection on sawtooth stability in ASDEX Upgrade and Mega-Ampere Spherical Tokamak
http://aip.metastore.ingenta.com/content/aip/journal/pop/16/7/10.1063/1.3187905
10.1063/1.3187905
SEARCH_EXPAND_ITEM