[PPT] - Introduction of HL-2M divertor design G.Y. Zheng 1 , X.R. Duan 1 , PowerPoint Presentation

SLIDE 1

HL HL-2A 2A G.Y. Zheng1, X.R. Duan1, X.Q. Xu2, D.D. Ryutov2, L.J. Cai1, X. Liu1, J.X. Li1, T.Y. Xia3, Y.Y Lian1, L. Xue1, Y.D. Pan1 and B. Li1

1Southwestern Institute of Physics, Chengdu, China 2Lawrence Livermore National Laboratory, Livermore, USA 3Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China

Introduction of HL-2M divertor design

Vienna, 29 September – 2 October 2015 The 1st IAEA Technical Meeting on Divertor Concepts

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HL HL-2A 2A

Content

1. Configuration design of HL-2M
2. Properties of divertor configurations
3. Divertor target geometry and simulation
4. Engineering design and X-point control
5. Plan and summary

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HL HL-2A 2A

R:

1.65 m

a:

0.40 m

Bt:

1.2~2.7 T

Configuration:

Limiter, LSN divertor

Ip:

150 ~ 480 kA

ne:

1.0 ~ 6.0 x 1019 m-3

Te:

1.5 ~ 5.0 keV

Ti:

0.5 ~ 2.8 keV Heating: ECRH/ECCD: 5 MW

(6 X 68 GHz/0.5MW/1s, 2 X 140 GHz/1W/1s)

NBI (tangential): 3 MW LHCD: 2 MW

(4/3.7 GHz/500 kW/2 s)

Diagnostics: over 30, e.g. CXRS, MSE, ECEI…

Fuelling system (H2/D2): Gas puffing (LFS, HFS,

divertor), Pellet injection (LFS, HFS), SMBI /CJI (LFS, HFS) LFS: f =1~80 Hz, pulse duration > 0.5 ms gas pressure < 3 MPa

HL-2A

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HL HL-2A 2A

Plasma current Ip = 2.5 (3) MA Major radius R = 1.78 m Minor radius a = 0.65 m Aspect ratio R/a = 2.8 Elongation Κ = 1.8-2 Triangularity δ > 0.5 Toroidal field BT = 2.2 (3) T Flux swing ΔΦ= 14Vs Heating power 25 MW

Main parameters

HL-2M (new tokamak, under construction)

HL-2M tokamak

Mission: high performance, high beta, and high bootstrap

current plasma; advanced divertor (snowflake, tripod), PWI.

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HL HL-2A 2A

 Test the engineering and physics issues relevant to to fusion reactor, such as ITER and CFETR.  Heat flux at target can be roughly compared, (total heating power is 25MW, λq less than 2mm with Ip = 3MA).

HL-2M

 Mitigation of heat flux at target to support HL-2M high performance operation.

High performance plasma and advanced divertor

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HL HL-2A 2A

CS and PF coil CS and PF coil parameters of HL parameters of HL-2M 2M

R(mm) R(mm) Z(mm) Z(mm) W(mm) W(mm) H(mm) H(mm) Ncoil Ncoil (Nr Nr×Nz Nz) Max(k Max(k A) A)

PF1

912 185 50.4 352.4 28(2×14) 14.5

PF2

912 586 50.4 352.4 28(2×14) 14.5

PF3

912 987 50.4 352.4 28(2×14) 14.5

PF4

912 1388 50.4 352.4 28(2×14) 14.5

PF5

1092 1753 183 220 28(5×6) 38

PF6

1501 1790 257 146 27(7×4) 39.41

PF7

2500 1200 183 220 28(5×6) 39

PF8

2760 480 183 220 28(5×6) 35.29

CS

748 116.75 3442.3 96(2×48) 110

HL-2M

CS and PF coil parameters of HL-2M

All of PF Coil current can be reversed for HL-2M

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HL HL-2A 2A

Standard divertor to advanced divertor

PF4/L and PF6/L as divertor coils to generate two separate X-points; PF5/L adjusts position of the two X-points to satisfy design requirements, such as snowflake divertor configuration.

Standard divertor

HL-2M Snowflake Tripod

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HL HL-2A 2A

Ip(MA) R (m) a (m) Κ δ up δ down li βp EFIT 1.2 1.71 0.56 1.698 0.265 0.735 1.17 0.645 CORSICA 1.2 1.71 0.55 1.694 0.255 0.745 1.17 0.64

EFIT CORSICA

Equilibrium benchmark by EFIT and CORSICA

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HL HL-2A 2A

Standard divertor Exact SF divertor SF divertor-plus SF divertor- minus

Ip(MA) R (m) a (m) Κ δ up δ down li βp 2.0 1.78 0.62 1.73 0.3 0.74 1.20 0.60

Snowflake configurations of HL-2M

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HL HL-2A 2A

Exact-SF

 When the plasma current reduces, the second X-point is fixed and first X point is forced to moved up by take advantage of poloidal field of CS coil:  When plasma current is 0.9MA, the distance between the X-points will be more than 50cm.

SF-minus Tripod Tripod

Snowflake divertor to Tripod dievrtor

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HL HL-2A 2A

Standard divertor

Weak Bp region of HL-2M SF divertor

Exact-SF Standard SF-plus SF-minus

D.D. Ryutov, et al., Contrib. Plasma Phys., 52, 539, 2012; PPCF, 54, 124050, 2012.

Fast convective heat transport around weak Bp can increase power sharing among the divertor legs and broaden the heat flux profile at target.

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HL HL-2A 2A

Weak Bp region of HL-2M SF/Tripod divertor

 When the distance between the two X-points becomes large, configuration loses features of snowflake divertor, becoming just two separate X-points;  Tripod configuration has a long divertor leg and three outgoing branches of the separatrix.

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HL HL-2A 2A

The local shear The integrated magnetic shear

Magnetic shear and curvature analysis of SF

 Same main parameters, R, a, Ip, k95, q95.  Same pressure and current profiles. (Local magnetic shear) Radius of curvature on outer mid-plane

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HL HL-2A 2A

The linear growth rate

Snowflake-minus improves P-B mode instability

The snowflake-minus has the closest X-point to the outer mid-plane is able to affect the property of ballooning modes. The second X-point improves the bad curvature in favor of the suppression of P-B modes.

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HL HL-2A 2A

SF SD

The TQ and the CQ phase

The hot vertical displacement phase

Configuration evolution during VDE

Parameters Ip (MA) R0 (m) a (m) κ95 βp li δ95 Bt (T) Value 1.00 1.71 0.55 1.65 0.60 1.06 0.25 2.20

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HL HL-2A 2A 30cm  The configurations (standard, snowflake and tripod) of HL-2M can be explored by optimizing the target geometry;  High cooling ability to support the high heat flux operation;  Flexible support structure, and well protection for cooling pipe system;  Easy installation, maintenance and update.

Divertor engineering design consideration

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HL HL-2A 2A

Standard divertor Exact snowflake Snowflake minus

Target plate geometry of HL-2M

Divertor target geometry is expected to be compatible with the configurations of HL-2M. Ip=2MA Ip=2MA

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HL HL-2A 2A

Bp / Bt value around target of HL-2M divertor

γmin ≈ Bp/Bt sinα., if γmin too small, the shadows and hot spots may appear on the plate; γmin is assumed to be 1/50 of a radian (roughly 1 degree).

Standard divertor Exact snowflake Snowflake minus

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HL HL-2A 2A

Connection length

If If λq=2mm of HL-2M, the plasma-wetted area: more than 1.5m2 of SF and about 0.3m2 of SD; P=12MW, 8MW/m2 of SF, 40MW/m2 of SD.

Standard divertor Snowflake minus

Mesh of SD and SF

0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.0 0.5 1.0 1.5 2.0 2.5

Ratio of connection length Distance from separatrix at outer middle plane (m)

Standard divertor Snowflake divertor

Surface expansion

0.00 0.01 0.02 0.03 0.04 20 40 60 80 100 120 140

Surface expansion Distance from separatrix at outer middle plane (m)

Standard divertor Snowflake divertor

Ip=2MA Ip=2MA

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HL HL-2A 2A

Simulation boundary conditions of SD and SF

 Cross field transport factor: D = 0.2m2/s, χe = χi = 0.5m2/s;  Power flows into SOL/Divertor regions: P = 12MW, Pi=Pe=6MW;  The density is fixed about 4cm inside the separatrix, and the upstream density ne,sep = 2.51019/m3;  The pumping gas speed S=50m3/s;  Carbon as impurity is included;  When Ip=2.0MA, the plasma density limit is about 1.51020/m3.

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HL HL-2A 2A

 2MW/m2 of SF, and about 5.8/m2 of SD.

Heat flux distribution of SD and SF

The heat flux distribution at outer target of standard divertor The heat flux distribution at outer target of snowflake minus

0.0 0.1 0.2 0.3 0.4 0.5 0.6 1x10

6

2x10

6

3x10

6

4x10

6

5x10

6

6x10

6

Heat flux W/m2

Distance from separatrix at outer target (m)

Standard divertor Snowflake divertor

Heat flux profiles at outer target

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HL HL-2A 2A

Electron density at outer target

Electron density at outer target of SD and SF

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.0 2.0x10

20

4.0x10

20

6.0x10

20

8.0x10

20

1.0x10

21

1.2x10

21

1.4x10

21

Density (/m3) Distance from separetirx at outer targte (m)

Standard divertor Snowflake divertor

Standard divertor Snowflake minus

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HL HL-2A 2A

Carbon ion density distribution of SD

C4+ C6+ C5+ C3+ C2+ C1+

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HL HL-2A 2A

C3+ C2+ C1+ C4+ C6+ C5+

Carbon ion density distribution of SF

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HL HL-2A 2A

Zeff distribution of SD and SF

20 40 60 80 100 1.0 1.5 2.0 2.5 3.0

Zeff From inner target along poloidal direction to ourter target

Standard divertor Snowflake divertor

Inner target Near X point Outer mid-plane Near X point Outer target

Standard divertor Snowflake minus

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HL HL-2A 2A

Peak heat flux at outer target of SF and SD

8 10 12 14 16 18 1x10

6

2x10

6

3x10

6

4x10

6

5x10

6

6x10

6

7x10

6

8x10

6

Heat flux (W/m

2)

Power flows into SOL/Divertor region (MW) Standards divertor Snowflake divertor 2.1x10

19

2.4x10

19

2.7x10

19

3.0x10

19

3.3x10

19

2.0x10

6

4.0x10

6

6.0x10

6

8.0x10

6

1.0x10

7

1.2x10

7

Standard divertor Snowflake divertor

Heat flux (W/m

2)

Electron density at outer mid-plane (m

3)

 The peak heat flux of SF is about 35% of SD (P=8-18MW);  ne,sep = 2.0*1019/m3，2.3MW/m2 of SF, 10.8MW/m2 of SF.

Peak heat flux at target with different power flows into SOL/Divertor region Peak heat flux at target with different Electron density at outer mid-plane

P=12MW

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HL HL-2A 2A

SF and Tripod divertor configurations, Ip = 0.5MA

Snowflake minus Tripod 2 Tripod 1

Ip = 0.5MA Ip = 0.5MA Ip = 0.5MA

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HL HL-2A 2A  D = 0.3m2/s, χe = χi = 1.0m2/s; P = 8MW, Pi = Pe = 4MW;  ne,sep = 1.4*1019/m3; Pumping speed is 50m3/s;  Carbon as impurity is included.

Mesh and boundary conditions of SD and SF

Snowflake minus Tripod Tripod

Ip = 0.5MA Ip = 0.5MA Ip = 0.5MA

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HL HL-2A 2A

0.00 0.01 0.02 0.03 0.04 0.05 10 20 30 40 50 60 70

Surface expansion Distance from separatrix at outer mid-plane (m)

Standard divertor Snowflake minus (YX-point = 120cm) Tripod 1 (YX-point = 110cm) Tripod 2 (YX-point = 100cm)

Connection length and surface expansion

Ratio of connection length of four kinds divertor configuration Surface expansion of four kinds divertor configuration

0.00 0.01 0.02 0.03 0.04 0.05 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Ratio of connection length Distance from separatrix at outer mid-plane (m)

Standard divertor Snowflake minus (YX-point = 120cm) Tripod (YX-point = 110cm) Tripod (YX-point = 100cm)

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HL HL-2A 2A

Heat flux distribution of SF and Tripod

0.0 0.1 0.2 0.3 0.4 0.5 0.6 1x10

6

2x10

6

3x10

6

4x10

6

5x10

6

Heat flux (W/m

2)

Distance from separatrix at outer target (m)

Standard divertor Snowflake minus (YX-point = 120cm) Tripod (YX-point = 110cm) Tripod (YX-point = 100cm)

Snowflake minus Tripod 2 Tripod 1 Standard divertor

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HL HL-2A 2A

Zeff distribution of different configurations

Snowflake minus Tripod 2 Tripod 1 Standard divertor

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HL HL-2A 2A

Carbon ion density distribution

C4+ C6+ C5+ C4+ C6+ C5+

Snowflake minus Tripod 2 Tripod 2 Tripod 2 Snowflake minus Snowflake minus

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HL HL-2A 2A

0.05

0.00 0.05 0.10 0.15 0.20 0.25

0.0 2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

5

1.0x10

6

1.2x10

6

1.4x10

6

1.6x10

6

1.8x10

6

Heat flux (W/m2) Distance from the separatrix (m)

Ip=1.2MA Ip=0.9MA Ip=0.7MA

0.05

0.00 0.05 0.10 0.15 0.20 0.25

0.0 2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

5

1.0x10

6

1.2x10

6

1.4x10

6

1.6x10

6

1.8x10

6

Heat flux (W/m

2)

Distance from the separatrix (m)

Ip=1.2MA Ip=0.9MA Ip=0.7MA

0.05

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

0.0 2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

5

1.0x10

6

1.2x10

6

1.4x10

6

1.6x10

6

1.8x10

6

Heat flux (W/m2)

Distance from the separatrix (m) Ip=1.2MA Ip=0.9MA Ip=0.7MA

0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45

0.0 2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

5

1.0x10

6

1.2x10

6

1.4x10

6

1.6x10

6

1.8x10

6

Heat flux (W/m2) Distance from the separatrix (m)

Ip=1.2MA Ip=0.9MA Ip=0.7MA

Ip = 0.7MA P =10MW ne= 1.5X1019/m3

Heat flux at targets of DN tripod divertor

Limit the power flows into inner divertor region. Handle most of heating power by outer divertor.

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HL HL-2A 2A

Vacuum Vessel First wall

Divertor

Divertor and first wall engineering design

First wall: Graphite; Target plate: CFC.

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HL HL-2A 2A

Divertor engineering design and fabrication

Cassette divertor structure of HL-2M

 CFC as the plasma facing material brazed on the copper alloy heat sink;  Cooling and baking channels are drilled inside the target copper plates to feed cooling water;  Channels are connected to pipes embedded inside the support frame;

Design of diveror structure: 80 sections, cassette, individual cooling, link structure for stress release

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HL HL-2A 2A

In-vessel and ex-vessel cooling circuits Feeding and collection pipes

Cooling design and analysis

Variation of highest CFC temperature with time

10MW/m2, 5s

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HL HL-2A 2A

Development of W coatings on graphite and CFC

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HL HL-2A 2A

Development of W coatings on graphite and CFC

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HL HL-2A 2A

P0 P1 P3 P2

X2

X1





exp exp

( , , ) C x y    Locally expand the Grad-Shafranov equation:

X-points Control methods

Find coefficients, Cexp, with the Br and Bz at points(P0-P3) from RTEFIT Control X1, X2, ρ and θ Created the relationship between the PF coils current and the X-point locations:

1

( )

T T PF

I A A A W B 



   

1 1 2 2

[ , , , , ]

iso T iso

G A X P G B x y x y               

whe here, e,

exp exp exp

1 1

r z PF r PF z PF

C C B B x x I C B I B I                         

X, P , G

2 2

r r r r z                 So So

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HL HL-2A 2A

Controlling the distance between two X-points

文件文件装置炮号时间模式迭代误差迭代次数运行模式平衡模式收敛与否已收敛位形位形中心位形中心小半径位形下单零上三角形变下三角形变截面积体积上拉长比下拉长比边界磁通磁轴磁通电流

Control two X-points

文件文件装置炮号时间模式迭代误差迭代次数运行模式平衡模式收敛与否已收敛位形位形中心位形中心小半径位形下单零上三角形变下三角形变截面积体积上拉长比下拉长比边界磁通磁轴磁通电流

1.5
1
0.5

0.5 1 1.5

5 10 15 20

800
600
400
200

200 400 sum__delt__Ipf(A) dIPF1U dIPF2U dIPF3U dIPF4U dIPF5U dIPF6U dIPF7U dIPF8U 5 10 15 20

1.5
1
0.5

0.5 1 1.5 x 10

4

sum__delt__Ipf(A) dIPF1L dIPF2L dIPF3L dIPF4L dIPF5L dIPF6L dIPF7L dIPF8L

PF5 PF3 PF2 PF6

2 4 6 8 10 12 14 16 18 20

50

50 100 150 200 R-Z(mm) The different of Xpoints' position from the target points dRX1 dZX1 dRX2 dZX2

dRX = RX-target - RX-cur dZX = ZX-target - ZX-cur

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HL HL-2A 2A

2 4 6 8 10 12 14 16 18 20

20

20 40 60 80 100 R-Z(mm) The different of Xpoints' position from the target points dRX1 dZX1 dRX2 dZX2

Controlling the second X-point

文件文件装置炮号时间模式迭代误差迭代次数运行模式平衡模式收敛与否已收敛位形位形中心位形中心小半径位形下单零上三角形变下三角形变截面积体积上拉长比下拉长比边界磁通磁轴磁通电流

dRX = RX-target - RX-cur dZX = ZX-target - ZX-cur

5 10 15 20

400
300
200
100

100 200 300 sum__delt__Ipf(A) dIPF1U dIPF2U dIPF3U dIPF4U dIPF5U dIPF6U dIPF7U dIPF8U 5 10 15 20

8000
6000
4000
2000

2000 4000 6000 8000 sum__delt__Ipf(A) dIPF1L dIPF2L dIPF3L dIPF4L dIPF5L dIPF6L dIPF7L dIPF8L

PF5 PF3 PF2 PF6

Control the second X-points

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HL HL-2A 2A

Phase I: no feedback control, plasma vertical position grows exponentially Phase II: feedback control of plasma vertical position start at the same time k95 1.53 1.56 1.58 Growth rate 169 177 186 k95 1.55 1.58 Growth rate 162 208

I I I

k95

95=1.58

I I I

k95

95=1.58

SF SF SD SD VDE control analysis of SF and SD divertor

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HL HL-2A 2A

Complicate configurations of HL-2M

More codes be involved in HL-2M divertor design and analysis, such as SOLPS-ITER, EMC3, SOLEDGE and so on. The affect of the second X-point will be investigated.

SLIDE 44

HL HL-2A 2A  According to the lower divertor operation results, the upper divertor will be designed and installed;  Based on the W coating technology developed at SWIP, the first wall and target plate with W coating will be carried out step by step;  The PWI researches based on HL-2M advanced divertor will be studied, as well as the compatibility with the high performance core plasma operation; The particle control ability of HL-2M will be enhanced.

Possible divertor engineering update

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HL HL-2A 2A

Summary

 Divertor configurations, properties analysis, target design, divertor simulation, engineering design and configuration control works are carried at SWIP for HL-2M divertor design.  Based on the design and analysis, standard and advanced divertors will be are explored in HL-2M experimental research project to study the divertor physics and mitigate heat flux for high heating power operation.  Advanced divertor is an important mission of HL-2M, the divertor physics, engineering design, code simulation and so on are challenges for us now.

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