Abstract
A review of the recent progress in understanding the transport in fully non-inductive, high bootstrap fraction H-mode discharges, developed on the DIII-D tokamak, is given in this paper. Experiments have demonstrated improved energy confinement due to the formation of an internal transport barrier in high bootstrap fraction H-mode discharges. Gyrokinetic analysis, and quasi-linear predictive modeling, demonstrates that the observed transport barrier is due to the suppression of turbulence, primarily due to the large Shafranov shift. E × B velocity shear does not play a significant role in the transport barrier due to the high safety factor. The ion energy transport is reduced to neoclassical for DIII-D discharges and electron energy and particle transport is reduced, but still turbulent, within the barrier. Deeper into the plasma, high levels of electron transport are observed. The electron energy transport in DIII-D is found to be due to electromagnetically enhanced electron scale modes. A contribution from fast ion driven instabilities is also possible. The kinetic ballooning mode plays a strong role in the region between the internal and H-mode edge transport barriers with two types of self-organized pedestal states observed.
| Original language | English |
|---|---|
| Article number | 115001 |
| Journal | Nuclear Fusion |
| Volume | 58 |
| Issue number | 11 |
| DOIs | |
| State | Published - Sep 27 2018 |
| Externally published | Yes |
Funding
This work was supported by the US Department of Energy under DE-FG02-95ER54309 and DE-FC02-04ER54698. DIII-D data shown in this paper can be obtained in digital format by following the links at https://fusion.gat.com/global/ D3D_DMP. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
| Funders | Funder number |
|---|---|
| US Department of Energy | DE-FC02-04ER54698, DE-FG02-95ER54309 |
Keywords
- gyrokinetic transport
- high bootstrap fraction
- transport barrier
