04Aa10
プラズマフィラメント輸送ダイナミクスにおけるイオン質量効果
Ion Inertial Effects on Plasma Filament Transport Dynamics
長谷川 裕記1, 2, 石黒 静児1, 2
HASEGAWA Hiroki1, 2 and ISHIGURO Seiji1, 2
核融合研1, 総研大2
NIFS / NINS1, SOKENDAI2
The filamentary plasma structures called “blob”
or “hole” which have been observed in various
magnetic confinement devices are thought to play animportant role in the radial plasma transport inboundary layer region. Also, many theoretical andnumerical investigations regarding the filament
propagation dynamics have been conducted on thebasis of two-dimensional reduced fluid models [1, 2].
On the other hand, we have studied the kinetic
dynamics on such filament phenomena with thethree-dimensional (3D) electrostatic particle-in-cell(PIC) simulation codes called “p3bd” and “up3bd”
codes [3-5] which have been developed for theinvestigations of boundary layer plasmas. Using thep3bd and up3bd codes, we have revealed the selfconsistent current system in a blob [6], thetemperature structure in a blob [6], and the ion
temperature effect on the blob dynamics [7, 8] andhave studied the dynamics between a filament andimpurity ions [9, 10]. Furthermore, the influence ofion mass on the filament dynamics has been
investigated with the 3D-PIC simulation [11, 12].
In this study, we have revisited the influence ofion mass on the filament dynamics and evaluated thethree effects of ion mass, that is, the sheath, thepolarization drift, and the gyro motion effects, anew.
From the simple fluid model, the radial propagation
speed vf is thought to be proportional to -1 by thesheath effect, in which  is the normalized ion
acoustic flux. On the other hand, in filament
dynamics without the sheath effect, vf is proportionalto -1/2 by the polarization drift effect, in which  isthe normalized mass density. That is, vf in lighthydrogen (H) plasma becomes slower than those indeuterium (D) and tritium (T) plasmas by the sheatheffect, while vf in H plasma becomes faster thanthose in D and T plasmas by the polarization drift
effect. Figure 1 shows the relation between  and vf
which are observed in the 3D-PIC simulations. Here,the solid and broken lines represent -1-1/2 vfH. This
figure indicates that the observed relation almost

satisfies vf ∝ -1-1/2. In the presentation, we will
discuss the origin of the slight difference between theobserved speeds and the theoretical estimation andthe effect of the connection length on the influencesof ion mass.

Fig. 1. Relation between  and the radial propagation
speeds observed in the 3D-PIC simulations. Here, csH
is the ion acoustic speed.
[1] S. I. Krasheninnikov, D. A. D’Ippolito, and J. R. Myra,J. Plasma Phys. 74, 679 (2008) and references therein.
[2] D. A. D’Ippolito, J. R. Myra, and S. J. Zweben, Phys.
Plasmas 18, 060501 (2011) and references therein.
[3] S. Ishiguro and H. Hasegawa, J. Plasma Phys. 72, 1233
(2006), doi: 10.1017/S0022377806006003.
[4] H. Hasegawa and S. Ishiguro, Plasma Fusion Res. 7,2401060 (2012), doi: 10.1585/pfr.7.2401060.
[5] H. Hasegawa and S. Ishiguro, Plasma Fusion Res. 12,1401044 (2017), doi: 10.1585/pfr.12.1401044.
[6] H. Hasegawa and S. Ishiguro, Phys. Plasmas 22,102113 (2015), doi: 10.1063/1.4933359.
[7] H. Hasegawa and S. Ishiguro, Plasma 1, 61 (2018),
doi: 10.3390/plasma1010006.
[8] H. Hasegawa and S. Ishiguro, Phys. Plasmas 26,062104 (2019), doi: 10.1063/1.5093561.
[9] H. Hasegawa and S. Ishiguro, Nucl. Fusion 57, 116008(2017), doi: 10.1088/1741-4326/aa7700.
[10] H. Hasegawa and S. Ishiguro, Nucl. Mater. Energy
19, 473 (2019), doi: 10.1016/j.nme.2019.04.005.
[11] H. Hasegawa and S. Ishiguro, Preprints of 27th IAEA
Fusion Energy Conference, TH/P7-12 (2018).
[12] H. Hasegawa and S. Ishiguro, 28th International Toki
Conference, P1-73 (2019).