平成24年ダイバータおよびPWI合同研究会 日時: 平成24年7月23日(月) - 24日(火)
場所: 筑波大学内・筑波大学自然 B 棟 119 講義室
非接触プラズマ研究と課題
名古屋大学大学院工学研究科
エネルギー理工学専攻
大野 哲靖
高性能炉心プラズマの定常維持・制御に対する
周辺プラズマの役割
必要条件
- 炉壁の耐久性
- 燃料粒子，不純物粒子輸送制御
炉心プラズマの定常維持・制御の基
盤を与える
境界プラズマ
炉心
プラズマ
Ｘ点
課題
プラズマ対向壁への粒子・熱負荷制御 - 非接触プラズマの理解と制御
セパラトリクス
熱・粒子流
磁気ダイバータ
ダイバータ板
ダイバータコイル
2
JT-60SAでのダイバータ板への熱負荷評価
具体的な設計を行うと問題が顕在化
‒ 過酷な熱・粒子負荷
部分非接触プラズマの
定常維持を前提とした
設計
Shinji Sakurai and JT-60SA design team, Proc. of Int. Sympo. on EcoTopia Science 2007, ISETS07 (2007)
Japan Society of Plasma Science and Nuclear Fusion Research
非接触プラズマとは
（１）ダイバータ部あるいはSOL領域からの強い放射損失
（２）ダイバータ板近くのプラズマ温度の著しい低下
The Japan Society of Plasma Science and Nuclear Fusion Research
The Japan Society of Plasma Science and Nuclear Fusion Research
（３）ダイバータ領域における中性ガス密度の増大
（４）ダイバータ板へのプラズマ粒子束及び熱流束の著しい低下
（５）ダイバータ領域において磁力線に沿ったプラズマ圧力の低下
高村秀一：プラズマ核融合学会誌1996
非接触プラズマの構造
Radiation
Zone
Ionizaion
Front
Ⅰ
Hot Plasma
Ⅰ
Momentum
Loss
Region
+
e
N
N
N
N
→放射冷却による
N
電子温度の低下 +
Divertor
Plate
B
Wall
Plasma Pressure
ダイバータ領域の中性ガ
ス圧の増加
→低温高密度プラズマ
の生成
→体積再結合の発生
Plasma Temperature
→プラズマの消失
Plasma Density
→ダイバータ板への
Distance along the Magnetic Field
熱負荷の減少
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
非接触プラズマの生成と電子-イオン再結合過程
.
Attached Plasma
Detached Plasma
接触プラズマ
接触プラズマ
非接触プラズマ
Heat Flux (kW/m2)
200
プラズマの消失
ガスバッファ層の形成
50
0
5
テキスト
近紫外発光スペクトル
15
P (mTorr)
21S-61P
0.8
10
21S-71P
非接触プラズマ
100
0
Intensity [mW cm-2 sr-1 µm-1]
..
プラズマ対向
材への熱流の
著しい低減
150
14
15
16
0.4
Continuum emission
into 23P
18
電子-イオン体積
再結合によるプラ
ズマ消失の実証
350
23P-p3D
0
330
340
Wavelength [nm]
３体再結合に伴う
高励起準位からの
発光線
放射再結合に伴う
連続スペクトル
17
20
20
分子活性化再結合過程
分子活性化再結合 MAR：Molecular Activated Recomination
H2(v) + e → H- + H
H- + A+ → A + H
(荷電交換再結合)
H2(v) + A+ → (AH)+ + H
(AH)+ + e → A + H
(解離性再結合)
振動励起水素分子を起点とした一
種の化学反応-�大きな反応確率
粒子バランス
∂ne
+ ∇⋅Γ = <σv>ionnenn - <σv>EIRne2
∂t
- <σv>MARnenH2
水素分子密度も重要！
3/s]
Rate
Coefficient
[m3/s]
反応速度係数[m
.
10-15
分子活性
化再結合
5x1019m-3
5x1018m-3
MAR
10-16
電子-イオ
ン再結合
10-17
EIR
電離
Ionization
10-18
10-19
0
1
2
3
4
Te [eV]
電子温度
[eV]
5
分子活性化再結合過程の実験的検証
テキスト
ヘリウム
ガス導入
水素ガス
導入
イオン粒子束の減少
３体再結合線の消失
N.Ohno et al.,
PRL
81(1998)818
炭化水素分子活性化再結合の実証 CH4+H+(or He+) →
CH4+ + H (or He)
CH4+ + e → CH3 + H
ダイバ
増加
→放射
電子
→低温
の生
→体積
MAP-IIでの
実験的検証
→プラ
→ダイ
熱負
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
Te[eV]
B
P[mTorr]
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
almost constant. These results indicate that the
Axial Positlon: X ( m )
electron energy is effectively lost by the
FIG. 6 . Axial profiles of :(a) Te,T,.n. and plasma
charge exchange and elastic collision
pressure ; (b) ionization and charge exchange
processes due.to a strong coupling between
energy losses, energy transition by temperature
electrons and ions in such a high density
relaxation process and plasma energy flux in Fig. 4
NAGDIS, Nagoya Univ.
plasma. In fact, the energy balance is
342 高密度
estimated from Fig. 6(b): ionization energy
drops around X=0.9m. Ti is almost constant.
Electron and ion energy loss rates are shown
loss 22.8%of total energy input and charge
in Fig. 6(b). Electrons mainly lose their energy
exchange energy loss 73.6%. Please pay
by ionization process near the plasma source
attention that electrons have the energy more
the 80% of plasma energy at X=Om.
because T, is relatively high enough forthan
ionization process. Above X-0.35m, the In a lower density case as shown in Fig.
ionization energy loss becomes small due
7, to
corresponding to Fig. 5, the axial profile of
a decrease
in
T,
and
the
energy
loss
with
the
低密度
低密度
T, does not change so much because
the energy
高密度
charge exchange and elastic collision becomes
loss due to ionization process is small and the
dominant. It should be noted that the energy
relaxations mentioned above is
loss rate of electron by energy exchange temperature
with
also
of weak, so there is no way to lose the
ions -K(T,-T~)has the same value as that
electron energy. Therefore, Ti is found to be
ions by charge exchange and elastic collisions.
rapidly
decreasing to a value around the
is
This is the reason why the ion temperature
0
0.2
0.4
0.6
0.8
1
neutral gas temperature To 0.03eV,
almost constant. These results indicate
thatambient
the
低密度
A
x
l
d
Porttion:
X
(
rn
)
Axial Positlon: X ( m )
the ions can not gain the energy from
the
electron energy is effectively lost bybecause
FIG. 6 . Axial profiles of :(a) Te,T,.n. and plasma FIG. 7.Axial profiles of :(a)
T, and plasma
charge exchange and elastic collision
the electrons.
In this case, loss
the energy
lossexchange
due
gain
N. Ohno CPP1996
pressure ; (b) ionization
and chargeionization
1 collision is pressure ; (b) ionization and charge exchange energy
高密度
a strong coupling between
processes due.to
to chargeenergy
exchange
radiation
losses, energy
by temperature
e transition
losses, energy transition
by temperature relaxation
電子ｰイオン間のエ
3
electrons and ions in such a high density
relaxation for
process
and plasma
energy and
flux inno
Fig. 4 process and plasma energy flux in Fig. 5.
not SO effective
plasma
Cooling,
recombination
ネルギー緩和が重要
is
plasma. In fact, the energy balance
detached
plasma
appears.
Figure
6(b)
gives
energy relaxation
estimated from Fig. 6(b): ionization energy
N. Ezumi JNM1997
4
loss 22.8%of total energy input and charge
charge exchange 中性ガス温度がイオ
2
exchange energy
loss - 73.6%. Please pay
i
非接触プラズマ生成
ン温度を決める
elastic collision
3
attention that
electrons
have
the
energy
more
に密度の閾値が存在
recombination
非接触プラズマ中のエネルギーバランス
-
-
-
-
B~~
-
than 80% of plasma energy at X=Om.
In a lower density case as shown in Fig.
-
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
非接触プラズマと
ELM の相互作用
（トカマク実験）
•Two negative peaks
( negative ELM) appears
in Dα emission.
A. Loarte et al.
Nuclear Fusion 38(1998)331.
ELM熱負荷模擬実験
Divertor Test Region
(~2 m)
DC Discharge Region
(~ 0.5 m)
Cathode
Floating
Electrode
Anode
Baratron gauge
Scanning Probes
2.03m
Primary Gas
(He)
Target Probe
X=0m
RF Generator
f=13.56MHz
P=10kW
Matching
Box
1.06m
1.39m
1.72m
Spectrometer
PM
HeI
( 2p-nd; 3<n<9 )
Digital
Oscilloscope
Secondary Gas
(He)
Isolation
Amplifier
高周波加熱によりELM熱負荷を模擬
非接触プラズマへの熱パルス印加実験
Emission Intensity (arb. units)
100
1st negative peak
Time evolution
of Balmer series
spectra at P ~
9mtorr
2nd negative peak
2p-3d:T
10
2p-4d:T
1
2p-5d:T
0.1
2p-6d:T
2p-7d:T
2p-8d:T
Negative spikes
appear
2p-10d:T
0.01
0.001
rf pulse
0
0.5
1
1.5
Time (msec)
2
2.5
10 9
10
Recombining
Phase
Ionizing
Phase
(a)2p-3d;T
8
n e=5x10 19m-3
10 7
10 6
10 5
n e =1x1019m-3
10 4
ne =5x1018m-3
10 3
0
1
eq
Te
Te
2
3
4
5
Emission Intensity (arb. units.)
衝突輻射モデルによるNegative Spikeの解析
10 7
10
(b)2p-8d;T
6
10 5
10 4
10 3
10 2
10
0
Te (eV)
1
2
Te eq
3
4
Te (eV)
Te
Transition between the ionizing phase and recombining phase gives minimum points
5
1st Negative Spikeの詳細観測
1.5
0.6
1
0.4
Ion Flux
0.2
0
0.5
2p-5d:T
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Time (ms)
- Ion flux to the target
plate is substantially
increased near the 1st
negative spike.
5
-10
4
-15
3
-20
2
-25
-30
1
0
0 0.1 0.2 0.3 0.4 0.5 0.6
Time (ms)
Ion Flux into the Target (a.u.)
2p-3d:T(587.5 nm)
constant at 1st negative spike.
End Plate Floating Potential (V)
0.8
- Floating potential remains almost
Ion Flux to the Target (a.u.)
RF Pulse
1
Emission Intensity (a.u.)
P He =7.5 mtorr
P rf =1 kW
2
Pump
(b)
P [mTorr]
divertor
test region
Anode
discharge
region
(i)
Pump
Cathode
Gas
Pump
Gas
Close
a gate valve Pump
Te [eV]
(a)
Volume 4, 000 (2009)
Cathode
Gas
Gas
15
10
32 kHz
CS(f)
Fig. 1 Schematic illustration of the linear plasma divertor simulator NAGDIS-II. (a) attached and (b) detached
plasma conditions.
(a)
Phase difference [ ]
0
-90
(iii)
30
20
10
0
6
4
2
0
0
(a)
(b)
(c)
-5
8.5 kHz
Detached
(b)
12
8
4
0
16
8
0
-10
0.9
0.45
Attached
10
10
Fluctuation
level of ne
Vf [V]
Anode
(ii)
Vs [V] ne [1018m-3]
and Fusion Research: Rapid Communications
(d)
0
-170
-180
-270
-360
0
Attached
-18
-90
Transition
-180
-270 (c)
-360
-1
10
(e)
Detached
0
10
1
2
10
10
Frequency [kHz]
3
10
Okazaki PFR2012
R(τ)
-0.8
-0.4
0
0.4
) Cross spectrum, CS ( f ), of ne and Vf under the attached and detached
Frequency
Fig. 2conditions.
Experimental
resultsdependence
of triple probe measurement at the r = 15 mm. Time evolutions of the moving average
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
周辺プラズマ領域での非拡散的径方向プラズマ輸送
第一壁近傍に比較的プラズマ密度が高く平坦
化した領域(2nd SOL)が存在する
→ 第一壁でのリサイクリングの増加→ 不
純物発生の増加
2nd SOL
径方向拡散によるプラズマ輸送のみでは説明
が困難
dn
Γ⊥ = − D⊥
+ nV⊥ (r )
dr
磁力線を横切る対流的プラズマ輸送？
€
→
Plasma Blob輸送
プラズマの塊(Blobs)が最外殻磁気面付
近で生成され， 磁力線を横切って第一壁
に向かって飛行する現象
M. V. Umansky et al. Phys. Plasma 5, 3373(1998).
第一壁
ne
1st SOL
Blobs
2nd SOL
セパラトリクス
Plasma Blob
Plasma Blob
S.I. Krasheninnikov, Phys. Lett. A 283 (2001) 368.
Plasma Blob
E
B ExB
E
R
E
E
E
P
ITER
P
P
NAGDIS-II
NAGDIS-II
ne<1020m-3
Te~10eV
P=3.6mTorr
probe
plasma column
P=9.0mTorr
P=13.6mTorr
2
NAGDIS-II
Plasma Blob
P
P
2
N. Ohno et al., J. Plasma Fusion Res. (Rapid Communications) 80 (2004) 275.
128x256pixel (~54x108mm2)
Probe 30000fps
P=11mTorr
B=0.05T
ExB
Plasma column
B
ErxB direction
~20mm
f=4.1kHz, 8.2kHz
B=50mT
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
熱的不安定性-X点MARFE
非接触プラズマは不安定→容易にＸ点MARFEに移行
N. Asakura et al. PSI18
X点MARFEによるコアプラズマ閉じ
込め特性の劣化
ダイバータ配位およびダイバータ排
気量制御による非接触プラズマの定
常維持・制御の実証が必要（高性能
炉心プラズマとの両立性）
the Heaviside function H , which is unity for 0
L . The Braginski
fluid
equations
are the
Due to
the spatial
separation
of the fronts caused by
n
H
n
the combined ion and electron momentum balance equation
the temperature dependence
of di€erent atomic pro,
(21)
n ion rec
cesses, power balance in the SOL (involving the power
t
n ionization source and recombination sink
ion particle
continuity equation, with
coming into the SOL from the core, Q , impurity ra-
非接触プラズマの熱的不安定性(1次元解析）
…imp†
nm
2nT
2
nm
at
rec
t
the combined ion and electron momentum balance equation
n
n
t
nm
n
H
ion
,
rec
n
and the combined ion and electron energy balance equation
nm
nm
2nT nm 2
at
rec
t
the combined ion and electron momentum balance equation
t
1
nm
2
3nT
2
52
0T
1
nm
2
T
3
5nT
and the combined ion and electron energy balance equation
nm
2
nm
2nT nm
Q H
3
2
at
rec
n f z Lz t nT at nE ion
,
2
SOL
diation loss in the SOL, Qrad , and QH ) can be written as
…imp†
QH ˆ QSOL À Qrad . We will see that the e€ects of imNagoya Univ. impose repurity radiation
plasma recombination
(22) and NAGDIS,
strictions on the power sources, QSOL and QH , which are
needed to sustain a high recycling
(21) SOL plasma at a given
upstream plasma pressure, Pup . Both QSOL and QH must
exceed
values which
À critical
Á
À Á depend on Pup , QSOL >
^ rec Pup , and associated, respec^ imp Pup and QH > Q
Q
tively, with impurity radiation and plasma recombination. Of course, in (22)
experiments, the e€ects of impurity
radiation and plasma recombination in the recycling
region may be strongly coupled. However, to emphasize
the di€erences in the physics of these instabilities, our
theoretical model can treat them separately by, for example, turning o€ the impurity or plasma recombination
(23)
e€ects.
(22)
E
1
1
52 T
nm 2
nm 3 5nT
0T
2
2
t
and the combined ion and electron energy balance equation
3nT
3
nT at nE
2
1
3nT
nm 2
2
t
n 2 f z Lz
Q H
ion
(23)
,
E
5 38
2
0T
1
nm
2
T
3
5nT
2.2. I
(23)
n 2 f z Lz
3
nT
2
at
nE
Q H
ion
E
,
R(T)
TR so
Since
nR %
increa
Co
with
(y ˆ L
condi
q2div Š >
const
this is
cause
exam
dealin
tion (
Ref. [
(as a
Ho
heat t
is im
vertor
that
comp
the ra
lous h
[7]. T
crease
shape
ations
q
qR j
plasm
32 in a tokamak diFig. 1. Schematic view of di€erent regions
vertor.
He
the i
plasm
sults
rap (nv)div sin θ
+ nn,div,aux vn ,
(9)
ecycling rate, (nv)div is the plasma partiinr target, and nn,div,aux is the auxiliary
Volume 6, 2403098 (2011)
g.
gas
puffing,
near
the divertor
plate.
e
n
and
λ
are
the
values
of
n
and
λn at the mesh
n,
j
n,
j
n
eat and
,
θ
relevant
to
the
neutrals
are
η
j, respectively. At the divertortrap
target and
we adopt the
Volume 6, 2403098 (2011)
部分非接触ダイバータ構造による安定化
ma and Fusion Research: Regular Articles
the dess-field
wing condition:
plasma.
n,div vn = ηtrap (nv)div sin θ + nn,div,aux vn ,
alnResults
(9)
is the recycling
rate,
(nv)div is thewere
plasma partieis,
ηtrap
moveITER-like
plasma
parameters
ing
is the
auxiliary inux the
atparticle
divertorinputs
target, from
and nn,div,aux
and
the core
to the
Fig. 2
ematic
d neutrals, e.g.
gas puffing, near the divertor plate.
23 −1
ndflux
1.5 × 10 s , respectively. The surwo
t aparameters
relevant to the neutrals are η , θ and
∼par640 m2 and the SOL width ∆SOL istrap
exam.
,aux
erefore, the
cross-field
and
par- Articles
Plasma
and Fusionenergy
Research:
Regular
plasma,
Fig. 1region,
The schematic
pictureand
of the multi-layer
ein
outer
the SOL
Q⊥SOL
S ⊥SOL , 1D model.
widths
−3
−3 −1
and
1021 On
mparameters
, hand,were
be
2.67analysis,
MWm
count only
in the5.0
SOL×
region.
thes other
effects
plasma
In
our
ITER-like
plasma
of the
cross-field source
terms
in the
divertor
region, S ⊥div
equathe
detached
tube
width
tothe
the
.tratio
The of
power
and
particle
inputs
from
core
to the
and Q⊥div , on stability of the detachment front had not been
ansport
23 −1
/∆SOL
= studied
1/3.
The
distance
from
the The
Dare
s , we
respectively.
sur80 MW
and 1.5
× 10
so far.
Recently,
showed that Q
⊥div can des terms
zsarea
to crease
the
target
= front
L)
isupstream,
the
the detachment
is ∼divertor
640speed
m2 ofand
the(zSOL
width
∆SOL but
is in
ASOL
in=the0)
Q⊥div is given an assumed value uni−2
ube,
S ,point
e×X
is previous
set at zwork
= 80
m. As for
in- and parm; our
therefore,
the
cross-field
energy
10
formly in the divertor region [22].
sourcetoterms
in
SOL
region,
Qsimulation
andstudy;
S ⊥SOL
= 0.8
evant
the neutral
particles,
ηtrap
⊥SOL
We the
extended
our
previous
we ,an−3
21
−3
the attached
and and
detached
tubes
5.0
×de10simultaneously,
m s−1 ,
toalyzed
be
2.67
MWm
estimated
auxiliary
neutral
densities
in
the
(1)
andthe
Q⊥div
are modeled
as follows;
where
S ⊥divof
(det)
ectively.
The
ratio
detached
tube
width
= to the
d tubes
at
the
divertor
plate
is
n
(2)
n,div,aux
(det)
n
− n(att)from the
D⊥div distance
1/3.
width
(att) is ∆DD /∆SOL =
Γ⊥div
19
−3 The
dcxnn,div,aux = 3.5S×⊥div10≈ ∆m ≈ ,−respectively.
,
(4)
div divertor∆target
DD ∆Γ
nation point (z = 0) to the
(z = L) is
Numerical Results
(det)
Plasma and Fusion Research: Regular Articles
time dependent analysis of t
plasma. We employed the
PDD plasma one-dimension
field particle and heat trans
prevent the detachment fron
such cross-field transport c
of a PDD plasma. It is al
the detachment front in a st
ble against the neutral densi
Finally, we make quali
Snapshots of the spatial profiles of n and T in the attached
ulation results reported her
tions. In many tokamak exp
((a) and (b)) and detached ((c) and (d)) tubes in the case
accompanies a high radiati
(5).X point (for example [
of S ⊥div = 0 and the non-zero Q⊥div expressed in Eq. the
Fig. 4 Snapshots of the spatial profiles of n and T in the cases of
= 2403098
Q⊥div =shown
0 in Figs. 2 (e) and (f) a
The n and T theprofiles
in and
the
ofVolume
S ⊥div
(b))case
and the non-zero
S ⊥div 6,
((c)-(f))
zero S ⊥div ((a)
(2011)
(accompanying the radiation
in the detached tube. The time step of each curve is the
are also shown
((e) and (f)). The detachment fronts that
same as Fig. 2.
beyond the X point in the
time dependent
of the
detachment
fronts inThe
a PDD transport. Such
move upstream
in the analysis
detached
tube
are simulated.
cross-field
perimental
plasma.
the ML1D
model2.4
to (blue),
describe
a observations. O
time of each
curveWeis employed
at t = 0 (red),
1.2 (green),
in interpreting such ex
PDD
one-dimensionally.
We found that thethat
cross3.7
4.9plasma
(turquoise)
andprofiles
6.2 (yellow)
Fig.(pink),
2 Snapshots
of the spatial
of n ands.T in the attached
vertor detachment, it is imp
field particle and heat transport in the divertor region
can
transport
((a) and (b)) and detached ((c) and (d)) tubes in the
casein the divertor regi
(att)
χ⊥div
− T As for inq⊥div
100 m,
and the XQ point
is set
at
z n¯= T80 m.
≈
≈
−
.
(5)
the
cross-field
energy
transport
⊥div
∆divof
∆DD ∆q ofηn and=T 0.8
4 Snapshots
the spatial
profiles
in the cases of
arameters Fig.
relevant
to the
neutral
particles,
trap
p, we
⊥div
(b))on
andbethe non-zero S ⊥div ((c)-(f))
theeffects
zero S ⊥divof((a)Qand
(3) examined
◦
prevent the detachment fronts from moving upstream, i.e.
of
S ⊥div = 0 and the non-zero Q⊥div expressed in Eq. (5).
such
transport
cancase
hamper
instability
[1] M. Shimada et al., Nucl.
The ncross-field
and T profiles
in the
of S thermal
⊥div = Q⊥div = 0
[2] D.J.
of aalso
PDD
plasma.
It is(f)).
alsoThe
found
that the position
of Ward, Plasma Phy
are
shown
((e) and
detachment
fronts that
(2010).
the detachment
a steady tube
stateare
is thermally
unstaITER Physics Expert Gro
move
upstream front
in theindetached
simulated.[3]
The
2391
(1999).
ble against
neutral
at the1.2
divertor
plate.
time
of eachthe
curve
is atdensity
t = 0 (red),
(green),
2.4 (blue),
[4] L. Loarte et al., Nucl. Fu
Finally,4.9
we(turquoise)
make qualitative
K. Tobita et al., Nucl. Fu
3.7 (pink),
and 6.2comparison
(yellow) s. of the[5]sim[6]
H.
ulation results reported here with experimental observa-Kawashima et al., Nuc
[7] S.I. Krasheninnikov et a
tions. In many tokamak experiments divertor detachment
(1999).
[8]
D.E.
Post and R.V. Jense
accompanies a high
radiation
peak
which
stagnates
near
M. Nakamura PFR2011
397 (1977).
Fig. 5 Snapshots of the spacial profile of the cross field particle
the Xsource
point
[27]).
the other hand,
[9] E.as
Hinnov and J.G. Hirsh
in the divertor
region ofOn
the detached
term(for
S ⊥divexample
[10]front
Yu. Gordeev et al., Pisma
the2cross-field
particle
diffusion
coefficients
of
showntube
in with
Figs.
(e)
and
(f)
and
Fig.
4,
the
detachment
2 −1
2 −1
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
Stored energy (MJ)
ne,baar (1019m-3) S
2.1
1
0.8
0.6
0.4
0.2
0
6
Ne
Prad/PNBI
0.7
0.6
0.5
Pradd/PNBI
4
2
0.4
0.3
Prad (M
MW)
0
Prad,max
0.2
4
0.1
2
0
P
1
2
3
4
rad
before Ne puffing
5
6
19
ne,bar before Ne puffing (10 m )
ne, div (1019m-33)
0
0.6
Peterson et al., PFR 1 (2006) 045.
•
:
60
•
:
30
0.3
0
20
Tee, div (eV)
7
-3
10
0
3.4
3.6
3.8
4
4.2
time (s)
4.4
4.6
P rad, P NBI (MW
W)
Ar seeding
1
08
0.8
0.6
0.4
0.2
0
6
4
2
Ar
•
•
10
0
10
PNBI
5
Prad
0
8
n e (10 19 m -3)
W p (MJ)
2.2
4
4.5
Time (s)
•
30
•
10
10
to divertor plates
共鳴摂動磁場を用いた非接触プラズマの制御
Edge surface layers
0.6
w/o Island
5
(a)
0
10
1
Radiation (a.u.)
20
10
(b)
0
15
2
1/3~1/10
3.5
4.0
4.5
(d)
0
•
•
•
1
3400A
3000A
2500A
1900A
1500A (collapse)
0A (collapse)
Lower: with the n / m = 1 / 1 resonant magnetic perturbation field. The inner
part with long field lines ͑bright/white scale͒ is called stochastic region, the
1.500 s
2.000 s
outer part with mixture of2.900
long ͑bright/white
s Detach scale͒ and short ͑dark scale͒ is
3.800 s
called
edge
surface
layers.
The
perturbation
field creates remnant island in
4.300
s
3.966 s Collapse
the stochastic region with the O-point located at outboard side in this sec19 m-3)legs are stretched from the
tion. The
divertor
in- 19
and
out-board
sides toward
ne (10
m-3
)
ne (10
target plates, which are not shown.
3
Collapse
inside the island with Ͼ10 eV. LCFS is located around R = 4.55 m. The
͑a few eV͒ plasma
is formed outsideWITH
the LCFS.
dense ͑ϳ1020 m−3͒ and
III. cold
DETACHMENT
SUSTANMENT
N/M=1/1
͑No. 85946 for withISLAND
island and No. 85948 for without island.͒
Gas puff
(1021 H/s)
2
3
4
time (s)
5
6
7
Figure 3 shows the time traces of plasma parameters
the sustained
detachment
ted in Fig. 7. Inobtained
the case inwithout
the island
͓Figs. 7͑a͒shot
andwith the n / m
14
= 1 / 10perturbation
field ͑shot
number:
85946͒.
7͑b͔͒, the Te monotonically
decreases
at the
entire
edge The discharge
was initiated
t =21.3
s bythe
neutral
beamtoinjection
͑NBI͒
4theplasma
6goes
8
10
region as the density
is 0
raised,atand
finally
heating,
ramped
up by
gas
puff
graduradiative collapse
at the and
lossthe
of density
density was
control.
In19
the
case
n
(10
m-3T) current, Fig.
e other
ally. The
particle
flux
͓ion hand,
saturation
with the island ͓Figs.
7͑c͒divertor
and 7͑d͔͒,
on the
e
3͑b͔͒ measured
by the Langmuir
probe
as a sum of 39
all
continuously decreases
with increasing
density
at thearrays,
outerFIG. 11. ͑Color
online͒ Evolution
of radiation
intensity measured by the
probe
tips,
increases
linearly
with
respect
to
the
density
rise
most region, Rresistive
Ͼ 4.75 bolometer
m, untilasthe
detachment
a function
of line transition.
averaged density, for different
until
detachment
transition
without
exhibiting
high
circles=
3400 A,
openrecycircles
/ m =transition,
1the
/ 1 perturbation
Icoil: closed
However, after nthe
it iscurrent,
stabilized
around
a few
=cling
3000 regime
A, triangles=
2500
A, diamonds=with
1900the
A, square
squares=scaling
1500 A,asand
that
is
characterized
eV, while keeping almost same T at the inner region
M. Kobayashi PoP2010
FIG. 6. ͑Color online͒ Time traces of ͑a͒ line averaged density, ͑b͒ radiation
intensity measured by AXUVD, ͑c͒ divertor particle flux, and ͑d͒ gas puff
rate, respectively. Thin lines: sustained detach with n / m = 1 / 1 island; thick
lines: radiative collapse without the island. ͑No. 85946 for with island and
No. 85948 for without island.͒
18
5.0
tion length inside island. Since the island is embedded in the
stochastic
the separatrix is no longer clear. The
2 region,
(b) LCFS
(d) LCFS
1
X-point
of
the
island
is, therefore,
visible
4.4
4.5
4.6
4.7
4.8 Sustained
4.9
4.4
4.5
4.6
4.7 not4.8
4.9in the plot. By
R(m)
strict definition,detach
it may not R(m)
be called so. In the following,
however, we may keep the term “X-point” representing the
FIG. 7. ͑Color online͒
Radialwhere
profilesaof
Te and
ne at thewould
edge region
͑a͒
region
clear
X-point
havefor
existed
without the
and ͑b͒ without the island, where the plasma goes to radiative collapse at
stochastization,
or
just
poloidally
opposite
side
to the
t ϳ 4.0 s, ͓͑c͒ and ͑d͔͒ with the island, where the sustained detachment was
realized at t Ͼ 2.900 O-point.
s. The
1latter case is characterized by the Te flattening
(c)
2
0
10
Iis (A)
0.5
0
4
3.0
(c)
Te (eV)
Te (eV)
FIG. 2. ͑Color
online͒ Connection length ͑LC͒ distribution
in poloidal cross
Attach
section at horizontally elongated section. Upper: without perturbation field.
Radiation intensity (a.u.)
•
•
•
•
•
100 (a)
Xw/ Island
ne (1019 m-3)
10
14
Phys. Plasmas 17, 056111 ͑2010͒
R (m)
056111-8
Kobayashi
et al.detach
Radiative collapse
(w/o island)
Sustained
(w/ island)
15
10
q// (W/m2)
Magnetic island
O-point
0
-0.6
2.5
(b)
ne (m-3)
(c)
177
-0.2
Detachment stabilization with n / m = 1 / 1…
10
19
10
10
-0.4
056111-5
Inboa
0.2
6
10
5
10
20
(a.u.)
n/m=1/1
/ 1/1
n/m=1/1
perturbation
X point
0.2
divertor
NAGDIS, Nagoya Univ.0
Wp (kJ)
Z (m)
0.4
(a)
0
(d)
Radiation
(by AXUVD)
10
Phy
(e)
0 500
200
100
0
5
Te (eV)
LHD
5
0.4
0
Hγ / Hβ
3
Stochastic region
ne (1019
10
Iis (A)
10
to divertor plates
10
400
(f)
Radia
300
gas puff (102
(g)
200
0.1
(h)
100
0
0
1
2
3
4
LCFStime(s)
(without island)
0 online͒ Time traces of variou
FIG. 3. ͑Color
4.2 shot with4.4
sustained detachment
n / m = 1 / 1 islan
and ͑b͒ divertor particle flux at upper and inbo
R
separated toroidally by ϳ160°. ͑c͒ Electron
temperature ͑open squares͒ at the inboard div
FIG. 12. T profiles during attachment p
muir probe, ͑d͒e power flux to inboard divert
cation for three different configurations. T
Langmuir probe, ͑e͒ radiation intensity measu
theemission
configuration
islands.
͑broken the
line͒,
͑f͒ sto
andfor
line
of H␣ without
the each probe,
configuration
is indicated
withl
diamagnetic
͑g͒ net NBI
heating ͑solid
detachment
was of
realized
for the con
H␤ measured
by
line͒,
and ͑h͒ ratio
H␥ to only
circles.toroidal locations indicated by toro
different
detachment occurs at t ϳ 2.9 s and was sustain
terminated by stop of NBI heating ͑No. 85946
detachment case and nearly 200 e
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.
SlimCS
#
#
Ip=16.7MA, β_p=2.5, l_i=0.6
fsxd=0.99
SlimCS
(No.20, 21, 22)
6
先進ダイバータへの適用に関する課題
先進ダイバータでの安定な非接触プラズマの生成は可能か
＃熱不安定性
＃磁場構造（エルゴディック領域の影響）
＃中性ガス（温度）の影響
＃径方向輸送（特にblob輸送）
NSTX snowflake experiment
(V.A. Soukhanowski, USBPO E-News, #42, p. 3, 2010; V.A.
Soukhanowski et al, PSI poster P1-28, Monday 24 May 2010)
Heat flux reduction by a factor of ~3
Easier detachment (no need in gas puff)
Carbon content in the core down by a factor ~ 2
Radiation from the core down by a factor ~ 2
Radiation from divertor up by a factor of a few
No noticeable adverse effect on core plasma density and temperature
非接触プラズマにおける課題
（１）原子･分子過程
電子ーイオン再結合、分子活性化再結合（水素、炭化水素）
（2）非接触プラズマ計測 NAGDIS
プローブ計測の異常性 （門先生)
MAP-II
（３）非接触プラズマのエネルギーバランスの理解
TPD
中性ガス温度の影響、輻射輸送の影響
（４）非接触プラズマの動的応答
ELM様熱負荷への応答、接触-非接触-再接触遷移過程
（５）非接触プラズマ中の径方向輸送
Gamma10
非拡散的輸送現象（Plasma Blobs) (田中先生）
（６）非接触プラズマの安定性
LHD
熱的不安定性、2次元効果（部分非接触）
JT-60U(SA)
（７）金属壁での非接触プラズマ生成
適切な不純物ガスの選定ーコアプラズマとの共存 （８）非接触プラズマの制御手法の確立
Puff&Pump, エルゴディック磁場（磁気島）（増崎先生）
（９）先進ダイバータ配位への適用性 ーダイバータ幾何学構造への依存性
Super-X, Snow flake, Isolated divertor etc.