TY - GEN

T1 - Current density calculation from particle orbit in RF-driven divertor plasma on QUEST

AU - Alam, Md Mahbub

AU - Nakamura, Kazuo

AU - Hasegawa, Makoto

AU - Tokunaga, Kazutoshi

AU - Araki, Kuniaki

AU - Zushi, Hideki

AU - Hanada, Kazuaki

AU - Fujisawa, Akihide

AU - Idei, Hiroshi

AU - Nagashima, Yoshihiko

AU - Kawasaki, Shoji

AU - Nakashima, Hisatoshi

AU - Higashijima, Aki

AU - Xia, Fan

AU - Mitarai, Osamu

PY - 2016/5/31

Y1 - 2016/5/31

N2 - We investigate and calculate particle orbits and the effect of particle orbits on plasma current density for nonrelativistic resonance condition in the present RF-driven divertor plasma on QUEST. We surveyed particle orbits for different values of parallel refractive index, particle initial positions and pitch angles on fundamental and second harmonic resonance conditions. We observed that for fundamental harmonic resonance condition when particle orbits are plotted on the poloidal cross-section for positive values of parallel refractive index, these orbits are started from the resonance surface and produced their orbits around the LCFS (Large Closed Flux Surface). These orbits carry positive current. When particle orbits are plotted for negative values of parallel refractive index, these orbits are started from resonance surface, but remained at the inside of the LCFS. These orbits carry negative current that reduced the overall plasma current. For second harmonic resonance condition when particle orbits are plotted on the poloidal cross-section most of the orbits remained in inside the LCFS and carry positive current. When we consider the value of parallel refractive index-0.4 and +0.4 some particle orbits arrived at the limiter and become lost particles. On the other hand, when we consider particle initial positions 0.16 m or more vertically far from the mid plane some banana orbits are produced. These banana orbits make the current density profile maximum at low field side region. From this calculation we got a hollow current density profile with current density peak at the low field side region outside of the LCFS. From this calculation we can infer that parabolic current density profile is possible, if we set the resonance surface outside of the magnetic axis by increasing the toroidal magnetic field coil current and make the plasma position inward by increasing vertical field coil current.

AB - We investigate and calculate particle orbits and the effect of particle orbits on plasma current density for nonrelativistic resonance condition in the present RF-driven divertor plasma on QUEST. We surveyed particle orbits for different values of parallel refractive index, particle initial positions and pitch angles on fundamental and second harmonic resonance conditions. We observed that for fundamental harmonic resonance condition when particle orbits are plotted on the poloidal cross-section for positive values of parallel refractive index, these orbits are started from the resonance surface and produced their orbits around the LCFS (Large Closed Flux Surface). These orbits carry positive current. When particle orbits are plotted for negative values of parallel refractive index, these orbits are started from resonance surface, but remained at the inside of the LCFS. These orbits carry negative current that reduced the overall plasma current. For second harmonic resonance condition when particle orbits are plotted on the poloidal cross-section most of the orbits remained in inside the LCFS and carry positive current. When we consider the value of parallel refractive index-0.4 and +0.4 some particle orbits arrived at the limiter and become lost particles. On the other hand, when we consider particle initial positions 0.16 m or more vertically far from the mid plane some banana orbits are produced. These banana orbits make the current density profile maximum at low field side region. From this calculation we got a hollow current density profile with current density peak at the low field side region outside of the LCFS. From this calculation we can infer that parabolic current density profile is possible, if we set the resonance surface outside of the magnetic axis by increasing the toroidal magnetic field coil current and make the plasma position inward by increasing vertical field coil current.

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U2 - 10.1109/SOFE.2015.7482308

DO - 10.1109/SOFE.2015.7482308

M3 - Conference contribution

AN - SCOPUS:84978891247

T3 - Proceedings - Symposium on Fusion Engineering

BT - 2015 IEEE 26th Symposium on Fusion Engineering, SOFE 2015

PB - Institute of Electrical and Electronics Engineers Inc.

T2 - 26th IEEE Symposium on Fusion Engineering, SOFE 2015

Y2 - 31 May 2015 through 4 June 2015

ER -