30E10P
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の解析
Analysis of Fast Ions Generated by the ICRF Heating in Helitoron J
岡田浩之1、和多田泰士2、村上弘一郎2、小林進二1、李炫庸2、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、杉本幸薫2、福島浩文2、荒井翔平2、沙夢雨2、剣持尚輝2、永榮蓉子2、笠嶋慶純2、原田伴誉2、中村雄一2、橋本絋平2、中村祐司2、佐野史道1
1
OKADA Hiroyuki , WATADA Hiroto2, MURAKAMI Koichirou2, KOBAYASHI Shinji1,
LEE Hyunyong2, et al.
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., 3NIFS0505

1010Exp.

Exp.

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1003

1002

1001

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1002

1010002468 10 12 14 16 18 20

E (keV)

(c)

0000

002

1010(b)(a)
10Cal.

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1010Cal.
fH(E) (arb.)

fH(E) (arb.)

Cal.

Exp.

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10fH(E) (arb.)

Low BumpinessMedium BumpinessHigh Bumpiness
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10101002468 10 12 14 16 18 20E (keV)02468 10 12 14 16 18 20

E (keV)

Fig. 1 The energy spectra from CX-NPA measurement(open symbols) in experiment and from Monte-Carlocalculation (solid symbols) for three bumpiness cases.
They are for the (a) high, (b) medium, and (c) low
bumpinesses, respectively.

symbols. The calculation reproduces the high-energy
tail up to 20 keV, which was measured only in the highbumpiness case (see Fig. 1(a)). No detectable data wasobtained in the charge exchange neutral analyzer(CX-NPA) measurements for energies above 6 and 8keV for the medium and low bumpinesses, respectively.
The measured and calculated energy spectra are also
identical for the medium and low bumpinesses. Thus,
the better production and confinement of fast ions inthe high bumpiness is probed in the Monte-Carlocalculation results.
0505

1010120
90

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10On-Axis Heating

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120
90

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10fH(E) (arb.)

Fast-ion confinement is one of most important issues
for helical devices since the alpha particle heating
efficiency in a fusion reactor depends on the loss cone
structure for fast ions in velocity space. The toroidal
ripple (bumpiness) of the magnetic field strength isone of key parameters for enhancing
confinement in the Heliotron J (R0 = 1.2 m, a =0.1-0.2 m, B0  1.5 T) configuration. The fast-ion
velocity distribution has been investigated using fast
protons generated by ion cyclotron range offrequencies (ICRF) proton-minority heating inHeliotron J with a special emphasis on the effect of thebumpiness and the heating position. Initial results forMonte-Carlo simulations of fast ions (protons)
obtained and the effects of the configuration had been
discussed, where the calculation was performed for theenergy spectra in relatively narrow region (< 10 keV).
In this paper, the energy spectra are extended up to 20keV by increasing the number of test particles.
Figures 1(a) to (c) show typical calculated energy
spectra for the three bumpinesses at the pitch angle of120°, where the fast ion flux is largest in theexperiment. In these figures, the vertical axis show thelogarithm of the ion counts in the bounded pitch angle
range from 115° to 125° in pitch angle. The
experimental values are also indicated by open

fH(E) (arb.)

103

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Inner-Side Heating

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1001

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1000

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1002468 10 12 14 16 18 20

Energy (keV)

1002468 10 12 14 16 18 20

Energy (keV)

Fig. 2 Calculated energy spectra of 90° and 120° in pitch
angle for the on-axis heating (a) and the inner-side
heating (b).

The position of ion cyclotron layer was shifted bychanging the injected wave frequency in the medium
bumpiness experiment. The fast ions were large in theon-axis case comparing with those in the inner-side
resonance case for centre chord measurement (110° inpitch angle) of the CX-NPA. The calculated energy
spectrum at the pitch angle of 90 in the on-axis
heating is slightly larger than that in the inner-side
heating case. However, the fast ions at 120 in theinner-side heating case are larger than those at 90. The
averaged energy of total fast ions in the calculation islarger in the inner-side case than in the on-axis case.
This result is consistent with the experimental fact thatthe bulk heating efficiency in the minority heating isbetter in the inner-side heating case.