22P128-P
Ion Energy Balance Analysis Using Charge-Exchange Neutral Particle
Analyzerin GAMMA10 Central-Cell
荷電交換中性粒子分析器を用いた GAMMA10 セントラル部におけるイオンエネルギーバランス解析
Takashi Ishii, Yousuke Nakashima, Katsuhiro Hosoi, Hisato Takeda, Kazuya Ichimura,
Hideaki Ueda, Shigehito Takahashi, Satoru Kigure, Satoru Hodaka, Tsuyoshi Imai
石井 貴、中嶋洋輔、細井克洋、武田寿人、市村和也、上田英明、高橋樹仁、木暮 諭、保高 暁、今井 剛
Plasma Research Center,University of Tsukuba,
1-1-1,Tennoudai, Tsukuba, Ibaraki 305-8577,Japan筑波大学プラズマ研究センター 〒305-8577 つくば市天王台 1-1-1
In the GAMMA 10 experiments using electron-cyclotron resonance heating (ECRH) with newlytransmission systems, the increase of charge-exchange neutral fluxes were observed by CX-NPA. The
electron temperature in the central-cell also increased from 22 eV to 53 eV by ECRH. In hot-ion mode that
hot ions are generated by ICRF, it was investigated that the loss by coulomb collision of ion and electron
occupied most of the ion-energy loss. In this estimation detailed analysis has been carried out inconsideration for the error of both Ti and Te.

1. Introduction
It is an important subject to investigate fast ion
behavior in order to discuss ion energy loss balance.
In GAMMA 10, a charge exchange neutral particle
analyzer (CX-NPA) has been installed perpendicularly to the magnetic axis to obtain hot ions in thecentral-cell. CX-NPA is a parallel-plate type energy
analyzer that analyzes neutral particle from theenergy of 0.2 keV to 30 keV. Recently thetransmission system of ECRH in the central-cell
was improved. Then plasma electron heating
experiment using ECRHc has been performed and asignificant increase of diamagnetism (DMcc) wasobserved in the period of ECRHc.
In this paper, the results of the neutral particle
fluxes using CX-NPA are reported and the detail ofion energy balance is discussed based on the resultsof ion energy-loss code.
2. Experimental Data
Figure 1 shows the temporal behavior of DMcc
and electron line density (NLcc). In this experiment,
ECRHc is injected from 105 ms to 125 ms. It is
obvious that DM immediately increased in theperiod of ECRHc. Figure 2 shows the radial profilesof plasma parameters in the central-cell: electrontemperature and ion temperature. The core iontemperature increased from 1.8 keV to 3.9 keV andthe core electron temperature increased from 22 eV
to 53 eV by ECHc.

Fig.1 Temporal behavior of DM and NL

(a)

(b)

Fig.2 Temporal behavior of plasma parameters in thecentral-cell ECRH experiment.
(a) electron temperature (b)ion temperature

3. Analysis of Ion Energy Loss Balance
In this study, we assumed four processes of ionenergy loss in order to clarify the detailed behaviorof fast ion.

(1) Loss by coulomb collision between ion andelectron.

ni ⋅ n e(Ti − Te )Te3 / 2(1)(2) Loss by electric charge exchange reaction
between ion and neutral hydrogen atom.

PCXH 0 ∝ ni ⋅ n H 0 (Ti − TH 0 )σ cxH 0 v(2)(3) Loss by electric charge exchange reaction
between ion and neutral hydrogen molecule.

Rcc<5.25

only RFECRHc+err
with ECRHc

Rcc<18.3

Pie ∝loss energy in RF and ECHc is much smaller thanmain area (Rcc<18.3 cm).

Qie
QcxH
QcxH2Qax

only RFECRHc+err
with ECRHc05101520253035

Total Loss Energy [kW]

PCXH 2 ∝ ni ⋅ nH 2 (Ti − TH 2 )σ cxH 2 v(3)

Fig.4 Total loss energy in the core and main area.
+err : in consideration for the error of bothTi(0) and Te(0)(4)

4. Summary
In the GAMMA 10 central-cell, plasma electron
heating experiment using ECRHc has been
performed. From the experimental results, thediamagnetic signal in the central-cell has increased
by ECRHc. The core ion temperature increased
from 1.8 keV to 3.9 keV and the core electrontemperature increased from 22 eV to 53 eV.
Recently investigation of the energy balance of
the ion started and the analysis of heating effects inECRHc has been performed for the first time in thecase of newly transmission system in ECRHc. From
the analysis, it was observed that loss by coulomb
collision of ion and electron is reduced by ECRHc.
The amount of Qie decreased from 30 kW (in theperiod of RF) to 15 kW. This decrease indicates thatthe relaxation of electron-drug due to hot-electron
produced by ECRHc. However, we can’t explain
this decrease in spite of consideration for the errorof ion and electron temperature. These results
indicate that other factors concern ion energy loss.

(4) Axial direction loss of ion.

Pax ∝ ni ⋅nihot⋅ (Ti ⊥ − Ti // ) / τ ii
nitotalThe result of analysis showed in Fig. 3. Qie (r)means the surface integral of the function Pie(r’)
over r’ from r’=0 to r’=r.
rQie (r ) = ∫ Pie (r ′)2πr ′dr ′(5)0Figure 3 shows that Qie decreased greatly when
ECHc was applied. Qie occupied about 90% of total
ion loss energy in the period of RF. This rate
decreased to 80% with rising electron temperaturein the ECRHc period. Another ion energy loss
slightly increased with rising ion temperature inECRHc. The total amount of loss energy also
decreased from 33 kW to 18 kW.

only RF1,2Qie
QcxH
QcxH2Qax
with ECRHc

0102030

Total Loss Energy (kW)40Rcc<18.3 cm

Fig.3 Total loss energy in the period of ECRH

When the energy balance of ions has been kept,
this decrease should not occur as far as input energy
to ions doesn’t depend on electron temperature. Inorder to investigate this difference of total energy,
we considered the error of ion and electrontemperature. Figure 4 shows the total loss energy inconsideration for the error of both Ti(0) and Te(0).
Total loss energy increased in consideration for theerror, but the difference still be existed. In the corearea (Rcc<5.25 cm) the difference between total

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[2] Y. Nakashima, Y. Hasegawa, et al. ,Rev. Sci. Instrum. 70 No.1 (1999) 849 .
[3] Y. Nakashima, M. Shoji, et al. ,Fusion Engineering and Design 34-35 (1997)
555 .