Dynamic retention characteristics in RF driven long ... › sites › fusionportal...VQUEST~12.8 m3...

1

K.Hanada1), N.Yoshida1), T.Honda2), A.Kuzmin1), H.Zushi1), I.Takagi3), T.Shibata4), A.Hatayama4), A.Fujisawa1), K.Nakamura1), H.Idei1), Y.Nagashima1), M.Hasegawa1), T.Onchi1), A.Higashijima1), S.Kawasaki1), H.Nakashima1), O. Watanabe1), O.Mitarai5), A.Fukuyama3), A.Ejiri6), and Y.Takase6)

1) Advanced Fusion Research Center, RIAM, Kyushu Univ., Japan.: 2) Interdisciplinary Graduate School of Engineering Sciences, Kyushu Univ., Japan.:

3) Graduate School of Engineering, Kyoto Univ.: 4) Keio Univ.: 5) School of Industrial Engineering, Tokai Univ.: 6) Graduate School of Frontier Science,

University of Tokyo.

Dynamic retention characteristics in RF driven long duration discharges on QUEST

Presented by K.HanadaRIAM

Kyushu University

What is dynamic retention?

Absor pt ion

Plasm a Induc ed-desor pt ion

Ref lec t ion

Di f fus ion

Desor pt ion

Plasm alayer

Bulklayer

Neut ra l Plasm a

TrappingDet rapping

Per m eat ion

Elementary step Image of diffusion-trap

Hydrogen isotope trapping in trap sites is likely to be long-tern retention and the other is desorbed via dynamic retention process during discharges. It is important to understand fuel circulation.

Permeation

SUS substrateDeposition layer

Trap site

Diffusion

Recombination

Potential

Distance

Desorption

( )( )

exp

exp

D B W

R B W

D E k T

k E k T

� −

� −

Dynamic retention can be monitored by outgassing just after plasma terminationA simple particle balance equation

When a dynamic retention plays a dominant role in fuel circulation, almost of injected fuel hydrogen will release just after plasma termination (~several hundreds second). Ratio between released and injected fuel hydrogen is a good index of how dynamic retention is dominantly working.

inΓnSN

inWΓin

WrΓoutWΓ

p pN τn iN τ

2

(1 )

in n W

in outW W W

in PW CX

P

outW W

nP P

P i

SN

r

N

kC

NdN N

dt

τ

τ τ

Γ = + Γ

Γ = − Γ − Γ

Γ = + Γ

Γ =

= − +

2

outn W

outW W

SN

kC

= Γ

Γ =

Par t ic leDeposi t ion, NW

Plasma particle, Np

NeutralParticle, Nn

Fueling, ΓinPumping, Sp

Ther m al desor p t ion, τW

Plasm a-induc eddesor pt ion, C1

Ref lec t ion , R

Par t ic le load , τp

Ion izat ion, τion

[nm]1000

0

1000

0

[nm

]

[nm]33.0

[nm]1000

0

1000

0

[nm

]

[nm]33.0

AFM

400 600 800 1000

1015

1016

1017

1018

Desorption Rate(/m2s)

Tem perature(K)

SUS316L unexposef SUS316L weak coloring SUS316L heavy coloring W 2012 S/S W-Equ

Particle fluxParticle Energy

Fuel recyclingRecombinationDefect density

Dynamic retention is working in fuel hydrogen circuit including core plasma

Dynamic retention is dominantly working during discharges on metal-dominant wall.

JET carbon wall JET ILW

Long-tern retention strongly depends on plasma-facing materials. Carbon is likely to retain hydrogen isotope chemically and difficult to release in low wall temperature such as 673K. While metal is easy to release it and dynamic retention is dominant in fuel circulation.

T. Loarer et al, Nucl. Fusion 47 (2007) 1112–1120

V. Philipps et al, J. Nucl. Matr. 438 (2013) S1067–1071

Most of stored fuel is desorbed during several tens seconds after the end of the

discharge.7

6

5

4

3

2

1

0

Stored H (x1020

)

76543210

Injected H (x1020

)

180 sec

Limiter IBnull ECR gas

300 sec

90 sec

T. Loarer et al, Nucl. Fusion 47 (2007) 1112–1120

QUEST ASDEX-U

These phenomena are common in devices with dynamic retention dominant wall.

CS

W blocks

Maintenance hole

Bt 0.25 T at R=0.64 m (CW)PF 4 pairsCS 3 coilsRF systems 2.45GHz 50 kW(CW) 8.2 GHz 400 kW(CW)

VQUEST~12.8 m3SQUEST~26.5 m2Spump~2.7 m3/s

W-PFCs (~ 30 %) in QUEST

Situation of QUEST PFCs until 2014SS

Since 2014 A/W, the hot wall made of W-plasma spray is installed to control wall temperature during discharges.

We successfully obtain long duration discharges with good repr

oducibility.50

40

30

20

10

0

TFC (kA)

4

3

2

1

0

PFC (kA)

3

0

ASDEX G

10

5

0

ASDEX_gauge01_V_ ASDEX_gauge02_V_ ASDEX_torr_ IG1_torr_ DiffPressure_V_ HighSpeedIG_V_

-20-10

01020

Ip_HE (kA)

543210

ne17 (m-3)

Ip_Hall_kA_ density_10^17_m-2_

1000

500-150

0

150 R_hall_mm_HE_ Z_hall_mm_HE

50

0

PC (kW)

1086420

PH (kW)

RFnet_kW_PC RFPH_INJ_kW_

0.25

0.006005004003002001000

Time (sec)

0.04

0.02

0.00

P250_2_V_ AXUV_V_

#27394-0 0 - 620 sec

TFC_kA_ PF17_kA_ PF26_kA_ PF35_1_kA_ PF35_2_kA_ PF4_kA_ MPP_CUR_SIG_kA_

50

40

30

20

10

0

TFC (kA)

4

3

2

1

0PFC (kA)

3

0ASDEX G

10

5

0

ASDEX_gauge01_V_ ASDEX_gauge02_V_ ASDEX_torr_ IG1_torr_ DiffPressure_V_ HighSpeedIG_V_

-20

0

20Ip_HE (kA)

543210

ne17 (m-3)

Ip_Hall_kA_ density_10^17_m-2_

1000

500-150

0

150 R_hall_mm_HE_ Z_hall_mm_HE

50

0

PC (kW)

1086420

PH (kW)

RFnet_kW_PC RFPH_INJ_kW_

0.25

0.006004002000

Time (sec)

0.040.020.00

P250_2_V_ AXUV_V_

#27395-0 0 - 750 sec

TFC_kA_ PF17_kA_ PF26_kA_ PF35_1_kA_ PF35_2_kA_ PF4_kA_ MPP_CUR_SIG_kA_

50

40

30

20

10

0

TFC (kA)

4

3

2

1

0

PFC (kA)

3

0

ASDEX G

10

5

0

ASDEX_gauge01_V_ ASDEX_gauge02_V_ ASDEX_torr_ IG1_torr_ DiffPressure_V_ HighSpeedIG_V_

-20

0

20

Ip_HE (kA)

543210

ne17 (m-3)

Ip_Hall_kA_ density_10^17_m-2_

1000

5000

R_hall_mm_HE_ Z_hall_mm_HE

50

0

PC (kW)

1086420

PH (kW)

RFnet_kW_PC RFPH_INJ_kW_

0.25

0.0010008006004002000

Time (sec)

0.04

0.02

0.00

P250_2_V_ AXUV_V_

#27396-0 0 - 1000 sec

TFC_kA_ PF17_kA_ PF26_kA_ PF35_1_kA_ PF35_2_kA_ PF4_kA_ MPP_CUR_SIG_kA_

#2739410min

#2739512min

#2739613min30s

• Hα signal level was feed-back controlled by regulation of gas fuelling and injected power was kept constant. Consequently plasma current and density could keep a certain level.

• Neutral pressure in rear side of divertor plate was gradually increasing and other signals seem not to change so much.

10

Heat load can be removed in SSO on QUEST

Rf power=40 kW

Particle recycling

Heat load on PFCs

3 min in IBN@ 40 kW with cooling the limiters and for 107 s @ 100 kW in SN-Lim. These were demonstrated without using recycling FB control.

Divertor Limiter

PFC Temp. is constant

Dynamic retention is dominant in QUEST exp. and required fuelling rate is gradually decreasing with plasma dura

tion.Inject H2

Evacuate H2

• 70% of injected hydrogen was retained in plasma facing wall just before the termination of the discharge and required fuelling rate is gradually decreasing and finally no fueling before the plasma termination (several 100 s) was observed.

• Outgassing just after plasma termination (~600s) indicates that dynamic retention is dominant.

(wall inventory)

Wall Saturation

Wall saturation was observed in higher wall temperature and was not decided by the number of wall retained hydr

ogen.

• Wall inventory is estimated by the difference between injected and evacuated hydrogen.

• A wall saturation was observed in only TW=373 K and lower TW could provide the higher number of wall retained hydrogen.

Wall temp. dependence of supplied hydrogen to keep the same Hα signal level.

Ha level:0.15

• Wall temp. has a significant impact in wall pumping rate.

• This clearly shows the property of dynamic retention is strongly affected by the wall temperature.

The Hα level has an impact to time-evolution of wall storing H.

Lower Hα level is likely to provide faster wall-saturation.

Many microscopic observations can support the model validation.2012AW-P16-WEMo(RC)

20nm

Substrate(Mo)

Deposition1

32

0.0 0.2 0.4 0.6 0.8 1.0

0.1

1

10

100

Intensity

Sputtering Tim e (s)

Fe Cr Ni C O W H M o Cu Si

2012AW

C

Fe Mo

Ni

CrO

W

Si

HCu

13 2

TEM Collaborated with Prof. Yoshida

Collaborated with Prof. Ohya

4x1020

3

2

1

0

Stored D (D/m2 )

300250200150100500

Time (min)

450

400

350

300

holder temperature (K)

Plasma irradiation

GD-OES

NRACollaborated with Prof. Takagi

1x1018

0

Desorption rate (m-2

s-1)

600550500450400350300

Temperature(K)

D2 Gauss Fitting peak_target Calculation

D2 ion implantation & TDS

QUEST wall model based on a simple diffusion-trap model.

Absor pt ion

Plasm a Induc ed-desor pt ion

Ref lec t ion

Di f fus ion

Desor pt ion

Plasm alayer

Bulklayer

Neut ra l Plasm a

TrappingDet rapping

Per m eat ion

To be published JNM.

( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )( ) ( ) ( ) ( ) ( )( ) ( ) ( ) ( ) ( )

( ) ( )

( )

( )max

2

2

0

0

, , , ,, , , , ,

,, , , ,

,, , , ,

,0,

,0

,

W W TA TBA TA B TB

TAA W A A TA

TBB W B B TB

WW

x

W

x x

C x t C x t C x t C x tD G x t k C x t G x t k C x t G x t

t x t tC x t

C x t F x t k C x t G x tt

C x tC x t F x t k C x t G x t

t

C x tkC t

x

C x t

x

G x t G e

β

β

=

=

−

� � � ��= + − − − −� � � � ��

��= −� ��

� �= −� ��

� �=� ��

��� =� ��

= ( ) 2 2

00

0

00

0

( , )1 ( , )

( , )

0 ( , )

( , )1 ( , )

( , )

0 ( , )

D Wx x x

TATA TA

TAA

TA TA

TBTB TB

TBB

TB TB

C x tC x t C

CF x t

C x t C

C x tC x t C

CF x t

C x t C

−

� − <�= �� ��� − <�= �� ��

QUEST wall model• All the model parameters except thickness of r

e-deposition layer are decided by D2+ ion implantation and TDS.

• Ion deposition profile is calculated by TRIM code using GD-OES component measurement.

• Recombination coefficient may be confirmed by the NRA experiment.

• Thickness of re-deposition layer will be decided with the colorimetric technique.

Need many measurements with microscopic observation.

It is difficult to apply plasma experiments in various devices.

To simplify the model, we assume

We try to propose a simple model to apply many of wall behaviors in various devices.

To confirm applicability of the model, we execute

Hα signal is roughly proportional to ionization rate in the wide range of Te and ne.

19

nH~1016m-3, nH2=1017m-3

Red line 10eV

Green line 50eV

ne dependence Te dependence

• Hα signal is a good index for monitoring ionization rate in the wide range of ne (1x1017-1019) and Te (5-50eV).

• Hα level control with a feedback manner could provide controlled ionization flux during long duration discharges.

Provided by Dr. Shibata in Keio Univ.

• In the CR model calculation, production rate of CX neutral is also proportional to intensity of Hα signal. This indicates that in-flux to the wall can be controlled by Hα level.

• The CX rate is approximately half of the ionization rate and plays important role in fuel circulation.

1. Hydrogen ions losing from the core plasma

2. Neutral Hydrogen atoms produced by CXIn steady state condition,

Ionization rate = loss rate of plasma ions

Te=50eV

Ionization rate ＝ Wall injected ion rate

IHα

The control of Hα signal in the QUEST plasmas gives constant in-flux to the plasma faci

ng wall.

inWΓ

nP P

P i

NdN N

dt τ τ= − +

Hα feedback level dependence of NW

Time-derivative NW

IHα[a.u.]

Wall temperature dependence can be reconstructed by the simple model with different k.

1.4x1021

1.2

1.0

0.8

0.6

0.4

0.2

0.0Wall-Stored H

600sec4002000Time (sec)

#27395@373K #26906@300K

1.0x1021

0.8

0.6

0.4

0.2

0.0

Injected H2

6004002000

Time (sec)

SN27395@373K SN26906@300K

Wall stored fuel

Evacuated fuel

Effect of trapping

• The same k is well-fitting.

• The estimated Γin are reasonable in the fitting.

• In the range of higher NW, effect of trapping appears.

k=1.6x10-23 Γin

The experimental data with various Γin can directly derive the simple model.

The effect of trapping reconstructs asymptotical behavior to wall-saturation

kt:Rate of trappingNtmax:The number of trap siteNt ＝ The number of trapping hydrgenIt should be noted that de-

trapping does not take into consideration.

Red:kt=0.001Blue:kt=0.002Htmax=2x1021

Nw+Ntd(

Nw

+N

t)/d

tWall-saturation

The estimated time constant in various devices.

• We assume the same value of recombination coeffcient, k0=1.6x10-37m4/s.

Device QUEST JET ITER DEMO

Thickness 0.1µm 1µm 10µm 100µm

Flux(m-2s-1)

3x1017 1x1020 1x1021 1x1021

Time(s) 150 250 800 8000

We have to measure the thickness of deposition layer and the recombination rate.

Summary

• Hydrogen (H) recycling and wall pumping properties during long duration discharges on a dynamic retention dominant wall are investigated on QUEST

• The H storing capability in the plasma-facing wall has a significant relation to intensity of Hα radiation and wall temperature experimentally, and is reconstructed well by a simple balance equation based on a surface-recombination limiting model applied to a re-deposition layer.

• A typical time constant representing wall saturation on dynamic retention dominant wall is provided by the balance equation, and is significantly longer than all the other global time constants such as energy confinement time and current diffusion time.

Plasma driven permeation probeMembrane= PdCuThickness = 20 micronTemp = 573K

Direct measurement of Retention flux Gas puff at every 40sec

GDP at 2Pa => Ku,Kd,DNumerical fitting NRA+PDP =>Ku,Kd

Where, K recombination coeff., D diffusion coef.

A.Kuzumin in this meeting

x

H2

),(),(

),0(),0(

2

2

0

2

2

tlxCKtlx

tCKx

CDtx

x

CD

t

C

Hrdpdp

Hrux

inc

HH

H

===Γ

+∂

∂−==Γ

∂∂=

∂∂

=

Global particle balance

A.Kuzumin in this meeting

Equations for particle balance expression

( ) ( )

( )

( ) ( )

( )

(1 ) 1 (1 ) 1

1 (1 ) 1

1 1

1

W W nW in out in g in out rec

ng rec

in

W Wout out

rec Win n

W nout rec

n n n

ion cx

NR r r R

NR r R

Rr r N

Nr R

N N N

τ

τ

τ

τ

τ τ τ

Γ = Γ − Γ = Γ − = − Γ − Γ = − −

− = − −Γ

Γ Γ= =− Γ −

Γ = −

= +

Can microscopic observations predict fuel circulation in plasma devises?

100nm

depo

t=70nm

100nm

depo

t=8nmCollaborated with Prof. Yoshida

Heavily colored region

Slightly colored region

SUS316L plate for fixing of

magnetic probe

400 600 800 1000

1015

1016

1017

1018

Desorption Rate(/m2s)

Tem perature(K)

SUS316L unexposef SUS316L weak coloring SUS316L heavy coloring W 2012 S/S W-Equ

＝＝＝＝＝＝＝＝＝＝＝＝＝ ( ＝＝＝＝ )＝＝ : ＝＝＝＝＝＝＝ Hα ＝＝＝＝＝＝＝＝ ( ＝＝＝＝＝＝＝＝ )

＝＝＝＝＝＝＝＝＝＝＝＝＝ ( ＝＝＝＝ )＝＝＝＝＝＝＝＝＝ : ＝＝＝＝＝

31

• Hα ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝• ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝• ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝ .

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝0.175:4x1018H/s,0.2:5.2x1018,0.25:7.6x1018k=1.6x10-23

Image of a diffusion and trap model

Move fast

SUS substrateDeposition layer

Trap site

Diffusion

Recombination

Potential

Distance

Deposition profile was decided by TRIM calculation based on TEM & GD-OES measurement

2012AW-P16-WEMo(RC)

20nm

Substrate(Mo)

Deposition1

32

0.0 0.2 0.4 0.6 0.8 1.0

0.1

1

10

100

Intensity

Sputtering Tim e (s)

Fe Cr Ni C O W H M o Cu Si

2012AW

C

Fe Mo

Ni

CrO

W

Si

HCu

13 2

TRIM CalculationTEM & GD-OES

500eV D

0 20 40 60 80 100

0

1x105

2x105

3x105

4x105

5x105

0.5keV-D 1.0keV-D 2.0keV-D

D Ions

Depth (nm)

Distribution of Injected D in Deposition of QUEST

Material: 31C-19O-33Fe-17W

( ) ( ) 2 2

0, D Wx x xG x t G e− −=

Hydrogen recycling can be reconstructed in long duration plasma on QUEST

5x1020

0

NH

2

1

0

Rg

2010

0

Ip (kA)

4003002001000Time (sec)

1

0H

α (a.u.)(b)

#24693 (a)

1.0

0.8

0.6

0.4

0.2

0.0

Rrec

300250200150100500

Time (sec)

1.0

0.8

0.6

0.4

Rrec

(#24693)20nm 50nm

100nm

8x1019

6

4

2

0

Stored H (H/m2 )

300250200150100500Time (sec)

1x1018

D/m2

5x1017

D/m2

2x1017

D/m2

1x1017

D/m2

JNM K.Hanada, et al. 2015

Global particle balance

Wall Stored H X 0.5

TMP, ＝＝＝＝＝＝＝(Spump=2.7m3/s)

＝＝＝＝＝ = ＝＝＝＝＝＝＝＝ + ＝＝＝＝＝＝＝＝＝＝

＝＝＝＝＝＝

Γfuel: ＝＝＝＝＝＝＝ Γab: ＝＝＝＝＝＝Γpump: ＝＝＝＝＝＝ Γrec: ＝＝＝＝＝＝＝Γwall ＝＝＝＝＝＝＝ ref: ＝＝＝

Simplified QUEST-wall model can reconstruct the particle flux depen

dence.

Simplified QUEST wall model

100 nm

80 nm

100 nm

100 nm

100 nm

80 nm

SOL plays an essential role in ionization. SOL model decides ionization rate from molecules a

nd atoms

1012

1014

1016

1018

1020

Number of Particles

0.60.40.20.0

Time[ms]

ne

nH

nH*

nH**

nH+

nH2

nH2+

nH3+

( )

2

2 2

2

2

2

20

20

1

2

1 11

2 2

1 1

2

p pHI H p

p

pHHI H p MH H p

p

H H pwW MH H p W in out

ab w p

Hp pw wW W

p ab w p

H Molecule

N NN N

t

NNN N N N r

t

N N NNkN N N CN

t N

NN NN NkN r CN

t N

N N

γτ

γ γτ

γτ τ

τ τ τ

�= − +

�

� = − + +�

� � �= − − − + + Γ − Γ� �� � �

� �� = − + − + − −� �� � �=

Hα ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

38

＝＝＝＝＝＝＝

Ip ＝＝＝

0.25 ＝＝＝＝＝＝＝＝＝＝＝＝＝＝ CX ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

Te:10eV

Te:50eV

Cross-section of the considering reactions for the CR model calculatio

n

39

The data file HYDHEL“Elementary Processes in Hydrogen-Helium Plasmas”

A calculated result with the CR model

tp=0.05sec,H2 ＝＝＝＝ 3 ＝ 1018 ＝＝＝＝＝＝＝＝＝＝ 5 ＝ 10-5

CR ＝＝＝＝＝＝＝ (0~0.002sec) CR ＝＝＝＝＝＝＝ (0~1sec)

Typical properties of particle balances in long duraion discharge

s

IAEA P?-?? A. Kuzmin, et al

＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

Sub Box

• ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝• ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝ Sub Box ＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝

inΓnSN

inWΓin

WrΓoutWΓ

p pN τn iN τ

inΓnSN

inWΓin

WrΓoutWΓ

p pN τn iN τ

outsub WΓ

Image of a diffusion and trap model

Permeation

SUS substrateDeposition layer

Trap site

Diffusion

Recombination

Potential

Distance

Desorption

Long-tern retention has an impact to fuel circulation in JET-class plasmas.

T. Loarer et al, Nucl. Fusion 47 (2007) 1112–1120

Many parameters make a complicated connection and lead to difficulties to promote international collaboration.

Fuel retention seems to depend on heating power, wall temperature, wall material and so on.

T. Loarer et al, Nucl. Fusion 47 (2007) 1112–1120

S. Brezinsek et al ＝ Nucl. Fusion 53 (2013) 083023

Calorimetric measurement was applied to investigate heat load distribution in various magnetic configuration

60

50

40

30

20

10

0

Power fraction (%)

Limiter IBnull Divertor

InnerLimiter

Divertor MovableLimiter

Vessel

Summary of heat load distribution on various magnetic configuration. Inner limiters locate on center stuck, and divertor limiters on divertor plates, and a movable limiter locates on outer vessel.

Measured Parameters:IP: -108499.797IPF17: 1077.304IPF26: 1241.405IPF35: -6.7895IPF42AB: -600.9293IextraPF: 0IHCUL: -1.3646

Fitted Parameters:IP: -108500.094IPF17: 1077.3015IPF26: 1241.3992IPF35: -6.7894IPF42AB: -600.9293IextraPF: 0IHCUL: -1.3646

CurR: 0.76CurZ: 1.04e-004MagR: 0.81MagZ: 1.05e-004

Fitted Parameters:β

p:0.41558β

t:2.9955li:1.011q95:4.811δ

up: 0.20597δ

down: 0.20597

κ: 1.0582Estor: 3736.2507JIP- : -108500.1 A

IP+: 0 A

R/m

Z/m

JRZ

shot:10760 Time: 1440ms

0.2 0.4 0.6 0.8 1 1.2 1.4-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

Hot wall is a control knob of fuel circulation.

47

Hot wall

Heater

Cooling panel

RadiationShield

Vacuum Vessel

ThermalIsolator

Some cooling channels will be installed on the vessel

Present Status of the hot wall. The hot wall is ready to operate.

Hot wall is expected to control H recycling during plasma dischar

ges. 1.0

0.8

0.6

0.4

0.2

0.0

Rrec

10008006004002000Time (sec)

373K

300K

373K 300K

Wall stored H Recycling ratio20x10

19

15

10

5

0

Stored H

10008006004002000Time (sec)

Summary

• Many of microscopic observations is well-collaborated in the QUEST wall model.

• Global wall behavior such as flux and wall temperature dependences can be expressed by QUEST wall model.

• Capability of the hot wall can be demonstrated by the QUEST wall model.

• International cooperated activities can support to obtain basic physical parameters and plasma induced phenomena such as co-deposition and defect production.

• For Integrated control to aim at SSO, SOL and plasma models should be established.

CS

W blocks

Maintenance hole

Bt 0.25 T at R=0.64 m (CW)PF 4 pairsCS 3 coilsRF systems 2.45GHz 50 kW(CW) 8.2 GHz 400 kW(CW)

VQUEST~12.8 m3SQUEST~26.5 m2Spump~2.7 m3/s

W-PFCs (~ 30 %) in QUEST

Present situation of QUEST PFCs

A model is proposed to handle what happened in the system.

( )

2

2 2

2

2

2

20

20

1

2

1 11

2 2

1 1

2

p pHI H p

p

pHHI H p MH H p

p

H H pwW MH H p W in out

ab w p

Hp pw wW W

p ab w p

H Molecule

N NN N

t

NNN N N N r

t

N N NNkN N N CN

t N

NN NN NkN r CN

t N

N N

γτ

γ γτ

γτ τ

τ τ τ

∂= − +

∂

∂ = − + +∂

∂ = − − − + + Γ − Γ ∂

∂ = − + − + − − ∂ =

8

6

4

2

0

n e (10

17m

-2)

403020100Time (sec)

460 sec

60sec

220sec

30

25

20

15

10

5

0Enhancement factor

50403020100Integrated Hα

#24692 50kW 5ms puff #24726 90kW 15ms puff #24727 90kW 10ms puff

＝＝＝＝＝＝＝＝＝

54

＝＝＝＝＝ (I.Takagi et al, Journal of Nuclear Materials 417(2011)564-567)