Speaker
Shuhei Sumida
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1002.pdf
Study on ion cyclotron emission excited by DD fusion produced ions on JT-60U
S. Sumida1, K. Shinohara2, R. Ikezoe1, M. Ichimura1, M. Sakamoto1, M. Hirata1, S. Ide2
1
Plasma Research Center, University of Tsukuba, Tsukuba, Japan
2
National Institutes for Quantum and Radiological Science and Technology, Naka, Japan
On JT-60U, ion cyclotron emissions (ICEs) which are related to deuterium-deuterium (DD) fusion
produced fast 3He (ICE(3He)), T and H ions were detected [1]. The previous work shows that
toroidal wavenumber and frequency of the ICE(3He) observed in JT-60U are close to those based
on the dispersion model of the magneto-acoustic cyclotron instability [2]. In this study, to
understand its excitation mechanism, we have evaluated and compared the fast 3He ion velocity
distribution between the cases with and without the ICE(3He) in a similar condition by using fast
ion transport code OFMC [3]. To evaluate the velocity distribution of the beam-thermal fusion
produced ions properly, we take into account effects of scattering-angle dependence of the fusion
products on their birth energies and pitch angles. On JT-60U, the ICE(3He) tended to become weak
and disappear when negative-ion-sourced NB (N-NB) was injected [1]. Figure 1 shows evaluated
energy and pitch angle distributions of the fast 3He ions at the plasma edge on the low field side in
the cases (a) without and (b) with the N-NB injection. In the case without the N-NB injection, the
distribution has a bump-on tail structure in the energy direction. On the other hand, the distribution
does not have the structure in the case with the N-NB injection. Relatively low energy 3He ions that
can reach the plasma edge are produced due to the N-NB injection. As a result, they eliminate the
bump-on tail structure. Hence, the comparison implies that the ICE(3He) is excited by the bump-on
tail structure in the energy direction.
Fig.1. Energy and pitch angle distribution of fast 3He ions (a) without and (b) with N-NB injection in E45335.
[1] M. Ichimura et al., Nucl. Fusion, 48, 035012 (2008). [2] S. Sumida et al., J. Phys. Soc. Jpn., 86, 124501 (2017).
[3] K. Tani et al., J. Phys. Soc. Jpn., 50, 1726 (1981).
