Back to Search
Start Over
Plasma Curent Start-up Experiment using Waves in the Lower Hybrid Frequency Range in TST-2.
- Source :
- AIP Conference Proceedings; 12/23/2011, Vol. 1406 Issue 1, p427-430, 4p
- Publication Year :
- 2011
-
Abstract
- Noninductive plasma current (I<subscript>p</subscript>) start-up experiments using RF power in the lower hybrid frequency range are being conducted on the TST-2 spherical tokamak. The lower hybrid wave (LHW) has demonstrated efficient current drive in conventional tokamaks. However, in spherical tokamak (ST) plasmas with very high dielectric constants (;[variant_greek_epsilon]∼ω<subscript>pe</subscript><superscript>2</superscript>/Ω<subscript>e</subscript><superscript>2</superscript>>1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that [variant_greek_epsilon]∼1) during I<subscript>p</subscript> ramp-up. Once I<subscript>p</subscript> reaches a level sufficiently high for neutral beam current drive, plasma can be densified and transformed into an advanced tokamak plasma dominated by the self-driven bootstrap current. Initial plasma start-up experiments were performed on TST-2 using a combline antenna which excites a traveling fast wave. After formation of toroidal flux surfaces, RF power and vertical field were ramped up to increase I<subscript>p</subscript>. Up to 12 kA of Ip has been obtained by this method. Soft X-ray measurements indicate that the electron temperature increases as I<subscript>p</subscript> increases, and hard X-ray spectroscopy indicates that energetic electrons build up as I<subscript>p</subscript> is ramped up. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0094243X
- Volume :
- 1406
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- AIP Conference Proceedings
- Publication Type :
- Conference
- Accession number :
- 70097083
- Full Text :
- https://doi.org/10.1063/1.3665007