03aE58P
ヘリオトロンJにおけるICRF加熱で生成された高速イオン分布の配位依存性
Configuration dependence of fast ion distribution generated by ICRF heating inHeliotron J
岡田浩之1、 村上弘一郎2、小林進二1、 水内亨1、長崎百伸1、南貴司1、山本聡1、大島慎介2、武藤敬3、木島滋1、史楠1、臧臨閣2、沙夢雨2、剣持尚輝2、笠嶋慶純2、原田伴誉2、佐野匠2、大谷芳明2、丸山正人2、野口正樹2、中村祐司2、佐野史道1
OKADA Hiroyuki1, WATADA Hiroto2, MURAKAMI Koichirou2,
KOBAYASHI Shinji1, MIZUUCHI Tohru1, NAGASAKI Kazunobu1,
MINAMI Takashi1, YAMAMOTO Satoshi1, OHSHIMA Shinsuke2,
MUTOH Takashi3, KONOSHIMA Shigeru1, SHI Nan1, ZANG Ling2, SHA Meiyu2,
KENMOCHI Naoki2, KASASHIMA Keijun2, HARADA Tomotaka2, SANO Takumi2,
OTANI Yoshiaki2, MARUYAMA Masato2, NOGUCHI Naoki2, NAKAMURA Yuichi2,
HASHIMOTO Kouhei2, NAKAMURA Yuji2, SANO Fumimichi1
1

京大エネ理工研、2京大エネ科、3核融合科学研
1
IAE Kyoto Univ., 2GSES Kyoto Univ., 3NIFS

Fast ion confinement is a critical issue for helicaldevices, since magnetic field ripple is ordinarily large.
In Heliotron J, a low-shear helical-axis heliotron (R0 =1.2 m, a = 0.1-0.2 m, B0 ≤ 1.5 T), fast ion velocity
distribution in the low density region has been
investigated using fast protons generated by ICRF
minority heating with special emphasis on the effect of
the toroidal ripple of magnetic field strength(bumpiness) and heating position [1, 2]. The majority
is deuterium and the minority is hydrogen. The
minority ions are easily accelerated in this heatingmode.
The high bumpiness among three bumpiness
configurations was preferable for the fast ion
confinement in the pitch angle scan experiment of theCX-NPA under the on-axis heating condition. In
medium bumpiness, the two locations of cyclotron
resonance layer were examined. The effective
temperature, which is estimated from the slope of theenergy spectrum between 1 keV and 7 keV, of theminority proton in on-axis heating was higher than thatin the inner-side heating; however, the bulk deuterontemperature in on-axis heating was lower. It is notconsistent with the heating scheme since most rf input
power is absorbed by minority ions in our experimental
condition. Fast ion’s distribution is occasionallylocalized in real space and there is the loss region invelocity space in the high energy area. The result of
fast ion observation should be analyzed including such
effects and the configuration dependence of such
effects should be clarified.
The two dimensional CX-NPA scan for the line ofsight is performed for the three bumpiness
configurations in on-axis heating condition. The scanregion is from -2° to 12° for the horizontal angle andfrom -2° to 6° for the vertical angle. The toroidal
position of the line of sight is changed in the horizontal
angle scan as well as the pitch angle of the observed
fast ions. The position of the line of sight in the obliquecross section is changed in the vertical angle scan. For
the most angles, the effective temperature of fastminority ions and the bulk ion temperature in the highbumpiness are highest among three configurations. In
the high bumpiness case only, the minority effective
temperature profile is asymmetrical against themagnetic axis at -2° and 0° of horizontal angle. In thelarger horizontal angle, the profile is symmetricalagainst the magnetic axis as in other two bumpinesses.
For the bulk ion temperature profile, no asymmetry isobserved in all bumpinesses.
To understand the experimental results and to obtain
the distribution of the fast ions in a plasma, Monte
Carlo calculation is performed. The code used involves
orbit tracing, Coulomb collisions and acceleration by
the ICRF heating. In the calculation results, thegeneration of fast ions in the high bumpiness
configuration is largest among three configurations.
Calculated pitch angle dependence for the volume
averaged fast ions agrees with the experimental resultof the on-axis line of sight. The fast ions are populated
more near the toroidal angle of 0° in the highbumpiness and the inner-side heating of the medium
bumpiness. The analysis of the spatial distribution of
the fast ions is in progress by comparing experimental
data with simulation results.
[1] Okada H et al. 2007 Nucl. Fusion 47 1346.
[2] Okada H et al. 2011 J. Plasma and Fusion Res.
SERIES 6 2402063.