TY - GEN
T1 - Plasma curent start-up experiment using waves in the lower hybrid frequency range in TST-2
AU - Takase, Y.
AU - Wakatsuki, T.
AU - Ejiri, A.
AU - Kakuda, H.
AU - Moeller, C. P.
AU - Ambo, T.
AU - Hanashima, K.
AU - Hiratsuka, J.
AU - Kasahara, H.
AU - Kumazawa, R.
AU - Nagashima, Y.
AU - Saito, K.
AU - Sakamoto, T.
AU - Seki, T.
AU - Shimpo, F.
AU - Shino, R.
AU - Sonehara, M.
AU - Watanabe, O.
AU - Yamaguchi, T.
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2011
Y1 - 2011
N2 - Noninductive plasma current (I p) 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 (ε∼ω pe 2/Ω| e 2≫1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that ε∼1) during I p ramp-up. Once I p 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 p. Up to 12 kA of Ip has been obtained by this method. Soft X-ray measurements indicate that the electron temperature increases as I p increases, and hard X-ray spectroscopy indicates that energetic electrons build up as I p is ramped up.
AB - Noninductive plasma current (I p) 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 (ε∼ω pe 2/Ω| e 2≫1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that ε∼1) during I p ramp-up. Once I p 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 p. Up to 12 kA of Ip has been obtained by this method. Soft X-ray measurements indicate that the electron temperature increases as I p increases, and hard X-ray spectroscopy indicates that energetic electrons build up as I p is ramped up.
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U2 - 10.1063/1.3665007
DO - 10.1063/1.3665007
M3 - Conference contribution
AN - SCOPUS:84857989690
SN - 9780735409781
T3 - AIP Conference Proceedings
SP - 427
EP - 430
BT - Radio Frequency Power in Plasmas - Proceedings of the 19th Topical Conference
T2 - 19th Topical Conference on Radio Frequency Power in Plasmas
Y2 - 1 June 2011 through 3 July 2011
ER -