Transport barriers in bootstrap-driven tokamaks
- General Atomics, San Diego, CA (United States)
- Chinese Academy of Sciences (CAS), Hefei (China). Inst. of Plasma Physics (IPP)
Experiments have demonstrated improved energy confinement due to the spontaneous formation of an internal transport barrier in high bootstrap fraction discharges. Gyro kinetic analysis, and quasilinear predictive modeling, demonstrates that the observed transport barrier is caused by the suppression of turbulence primarily from the large Shafranov shift. It is shown, that the Shafranov shift can produce a bifurcation to improved confinement in regions of positive magnetic shear or a continuous reduction in transport for weak or negative magnetic shear. Operation at high safety factor lowers the pressure gradient threshold for the Shafranov shift driven barrier formation. Two self-organized states of the internal and edge transport barrier are observed. It is further shown that these two states are controlled by the interaction of the bootstrap current with magnetic shear, and the kinetic ballooning mode instability boundary. Election scale energy transport is shown to be dominant in inner 60% of the profile. Energetic particle driven instabilities could also be playing a role in the thermal energy transport in this region.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- FC02-04ER54698; FG02-95ER54309
- OSTI ID:
- 1459670
- Alternate ID(s):
- OSTI ID: 1438969
- Journal Information:
- Physics of Plasmas, Vol. 25, Issue 5; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Progress of physics understanding for long pulse high-performance plasmas on EAST towards the steady-state operation of ITER and CFETR
|
journal | December 2019 |
Enhanced stiffness weakening and confinement improvement by the linear electromagnetic effect in relatively high- q and low magnetic-shear plasmas
|
journal | April 2019 |
Key effects on the confinement improvement of the ASDEX Upgrade hybrid scenario
|
journal | September 2019 |
The dominant micro-turbulence instabilities in the lower q 95 high β p plasmas on DIII-D and predict-first extrapolation
|
journal | November 2019 |
Similar Records
Theory of transport in high bootstrap fraction H-modes with internal transport barriers
Transport at high ${\beta_p}$ and development of candidate steady state scenarios for ITER