U.S. Department of EnergyOffice of Scientific and Technical Information
Symmetric spectrum current drive due to finite radial drift effects
Abstract
The drift surfaces of minority heated ions differ from flux surfaces due to finite poloidal gyroradius effects. As the minority poloidal gyroradius approaches radial scale lengths in the plasma the difference between drift and flux surfaces can modify the heating and lead to a symmetric spectrum minority counter-current being driven. In response, a corresponding overall net co-current of comparable size is driven. This beneficial symmetric spectrum current drive in a tokamak is due to the parallel velocity asymmetry in the drift departure from a flux surface. As this new source of driven current is a side effect of minority heating it comes without any additional economic cost to reactor power balance. The symmetric spectrum current driven for near Maxwellian minorities is evaluated by an adjoint method and found to be modest. However, minority heating typically results in strong non-Maxwellian features on minority distributions so it may be possible to drive significantly larger co-current. A related evaluation is performed for alpha particles in a deuterium minority heated plasma with a tritium majority. The low density of the alphas tends to keep this driven symmetric spectrum current small, but at very high heating levels a significant co-current might be driven. Other mechanismsmore »
- Authors:
-
- OSTI
- Publication Date:
- DOE Contract Number:
- FG02-91ER54109
- Research Org.:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
- OSTI Identifier:
- 1880300
- DOI:
- https://doi.org/10.7910/DVN/LWEJDP
Citation Formats
Catto, Peter J. Symmetric spectrum current drive due to finite radial drift effects. United States: N. p., 2018.
Web. doi:10.7910/DVN/LWEJDP.
Catto, Peter J. Symmetric spectrum current drive due to finite radial drift effects. United States. doi:https://doi.org/10.7910/DVN/LWEJDP
Catto, Peter J. 2018.
"Symmetric spectrum current drive due to finite radial drift effects". United States. doi:https://doi.org/10.7910/DVN/LWEJDP. https://www.osti.gov/servlets/purl/1880300. Pub date:Tue Nov 27 04:00:00 UTC 2018
@article{osti_1880300,
title = {Symmetric spectrum current drive due to finite radial drift effects},
author = {Catto, Peter J.},
abstractNote = {The drift surfaces of minority heated ions differ from flux surfaces due to finite poloidal gyroradius effects. As the minority poloidal gyroradius approaches radial scale lengths in the plasma the difference between drift and flux surfaces can modify the heating and lead to a symmetric spectrum minority counter-current being driven. In response, a corresponding overall net co-current of comparable size is driven. This beneficial symmetric spectrum current drive in a tokamak is due to the parallel velocity asymmetry in the drift departure from a flux surface. As this new source of driven current is a side effect of minority heating it comes without any additional economic cost to reactor power balance. The symmetric spectrum current driven for near Maxwellian minorities is evaluated by an adjoint method and found to be modest. However, minority heating typically results in strong non-Maxwellian features on minority distributions so it may be possible to drive significantly larger co-current. A related evaluation is performed for alpha particles in a deuterium minority heated plasma with a tritium majority. The low density of the alphas tends to keep this driven symmetric spectrum current small, but at very high heating levels a significant co-current might be driven. Other mechanisms to drive co-current with a symmetric spectrum are discussed and estimated, including asymmetric electron drag and focusing of the applied minority heating radio frequency fields.},
doi = {10.7910/DVN/LWEJDP},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 27 04:00:00 UTC 2018},
month = {Tue Nov 27 04:00:00 UTC 2018}
}