Speaker
Leonid Askinazi
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1084.pdf
Ion cyclotron emission properties in NBI-heated TUMAN-3M plasma
L.G. Askinazi, G.I.Abdullina, A.A. Belokurov, V.A. Kornev, S.V. Krikunov, S.V. Lebedev,
D.V. Razumenko, A.I. Smirnov, A.S. Tukachinsky, N.A. Zhubr
Ioffe Institute, St. Petersburg, Russian Federation
Ion cyclotron emission (ICE) in routinely registered in many tokamaks. It was recently
observed in the TUMAN-3M tokamak [1, 2] in ohmically and neutral beam injection (NBI)-
heated regimes in D and H plasma. This presentation describes some characteristic features of
NBI-induced ICE observed in TUMAN-3M, with emphasis on spectral structure of the
emission. In contrast to many other observations, ICE frequency ωICE in the TUMAN-3M
NBI scenario corresponds to a core location of a radiating body, close to the plasma center. In
NBI-heated plasma, ICE generation is usually explained by the presence of fast particles
(beam ions or fusion charged products) with high transversal kinetic energy. In the TUMAN-
3M, high energy charged fusion products are not confined due to the low toroidal field (BT=1
T) and small size (R/a = 0.55 m / 0.25 m) of the tokamak and could not effectively excite ICE.
NBI in the TUMAN-3M is performed in co-current tangential direction; as a result the fast
ions with high transversal energy are born predominantly in the plasma periphery and then
move to the core plasma along drift trajectories. Among these trajectories, a class of potato-
like ones features the strong deviation from magnetic surface. This kind of trajectories looks
beneficial for central ICE generation, as they have long vertical part located close to plasma
center; particle drifting along this vertical part spends a longer time in a region of constant
toroidal field, i.e. constant ωICE. Thus, these particles could be a possible candidate for central
NBI ICE excitation in the TUMAN-3M. This model reproduces qualitatively well other
important features of NBI ICE observed in the deuterium plasma in TUMAN-3M, such as
frequency line splitting (fine structure) and ICE frequency dependence on beam energy. The
former is explained by the presence of different energy components (1/2E0, 1/3E0 etc ) in the
beam, in addition to main energy E0; the latter ensues from (a weak) dependence of location
of vertical part of the trajectory on the fast ion’s energy.
Experimental study of the ICE was supported by Russian Science Foundation (Project
# 16-12-10285). Modeling of the fast ion trajectories was supported by Ioffe Institute.
References
1. Lebedev S.V. et al, EPJ Web of Conferences 149, 03010 (2017), https://doi.org/10.1051/epjconf/201714903010
2. L.G.Askinazi et al, 15th IAEA TM on Energetic Particles in Magnetic Confinement Systems, 5-8 Sept. 2017,
Princeton, P2. https://nucleus.iaea.org/sites/fusionportal/Shared%20Documents/EP%2017th/BoA.pdf
