Design Point Studiesfor next step device

National High-heat-flux Advanced Torus Experiment

NHTX

C Neumeyer

6/8/6

Outline

• Background• Method• Physics Assumptions and Plasma Shapes• Engineering Assumptions and Issues

- TF inner leg cooling- Heat removal from machine- Divertor heat removal- Power supply utilization

• Results• Conclusions

NSTX Center Stack Upgrade ~ 10s pulse

- adiabatic water cooled, sub-cooled, LN2- Paux= 10-20MW- full, partial inductive- OH coil, iron core

NSTX Center Stack Upgrade ~ 20-60s pulse

- active water cooled- retain VV, PF coils, TF outer legs

NSTX Upgrade ~ 60s pulse

- replace center stack, PF, TF outer legs- retain existing VV (kappa*a <=1.3m)

NSTX Replacement ~ 60s pulse

- all new machine

Background: Options Studied

Attractive mission:Ip ~ 4MABt ~ 1.5TPaux ~ 38MW

Attractive mission:Ip ~ 4MABt ~ 1.5TPaux ~ 38MW

Highlights of New Machine

High P/R- plasma should accept Paux = 32MW NBI + 6MW RF = 38MW

Non-Inductive Sustainment- solenoid sized for ramp-up flux only

Long Pulse- active water cooling, 60 second pulse

Full Use of PPPL/TFTR Infrastructure- full MG energy + grid power- full PS capacity- full NBI capacity

Some Incremental Infrastructure Required- water flow- 138kV substation

Methodology

• XL-based “systems code” using non-linear optimizer (‘Solver”)

• Jardin/Kessel physics algorithms used for NSST were starting point

• Continued evolution with Peng, Rutherford, Kessel for CTF studies

- See PPPL Report 4165 “Spherical Torus Design Point Studies”

• Engineering & physics algorithms tailored to subject situation

Physics Assumptions

A 1.5-2.0 100% flux surfaces

R0+a 1.473m10cm inboard of antenna guards on existing NSTX

R0 f(A, R0+a)kappa 3.674/SQRT(A) per RGdelta 0.6 Fixedqcyl 2.5 Fixedbeta_N <= limit 6.43-1.02*A per RGConfinement Ti=Te, HH98=1.3 Fixed

Solenoid Flux85% Hirshman-Neilson flux, ramp-up only

85% factor matches formula to Menard data

Paux <=4*8+6=38MW Beta limited

PF Currents Scaled from Menard equilibrium @ 3MA (A=1.8)

Solutions maximize Ip*Paux

NSTX & NSTX-U ShapesA=1.5-2.0

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

r(m)

z(m)

Z=1.3m~ limit of existing VV

Z=1.3m~ limit of existing VV

Range of Cross Sections

= 3.674/SQRT(A_100)=0.6= 3.674/SQRT(A_100)=0.6

€

R(θ ) = R0 + a∗cos(θ +δ ∗sin(θ ))

€

Z(θ ) = κ ∗a∗sin(θ )

R0+a=1.473R0+a=1.473

Simple limiter shape model:

NSTX & NSTX-U ShapesA=1.8

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

r(m)

z(m)

Limiter model vs. Divertor separatrix flux surface from J. Menard equilibria @ A=1.8

Engineering Assumptions

TF Inner Leg Heating Jcu_avg <= 5.75kA/cm^2

dz=f(kappa*a), packing fraction f(Jcu_avg,dZ) based on KCOOL, v=10m/s, Tcu_max=100C

TF Inner Leg Stress Radial stress <=138MPA Tracking insulation shear stressTF Outer Leg Heating Jcu_avg <= 1.5kA/cm^2 New outer leg <= 4*CSA of existingTF Outer Leg Stress Not ModeledOH Heating G-function adiabatic dz=f(kappa*a)OH Stress Hoop stress <=138MPA Need to include axial stress

PF Heating Jcu_avg <= 2.5kA/cm^2

KCOOL analysis assumes conductor area per turn 1.5*CSA of existing PF coils, 10 turns per cooling path, 15kA per turn

PF Stress Not Modeled

Center Stack Casing (VV) Heating and Radial Build

25% of Paux impinges on CS over dZ=2*kappa*a

Radial build based on heat flux, ferritic steel w/15% cooling fraction, 400C, 4MPa He cooling at 150m/s

PFC Heating Not ModeledPFC Stress Not ModeledTransrex Capacity 15kA/PSS, 3.25kA rms rms is limiting

MG TF/PF/OH Loads W<=4.5GJ,

CCV on during pulse

GridNBI/MG/BOP Loads

P<=200MW

Approved by PSE&G for TPX, requires local D-site substation and p.f. correction

Cooling Water Systems

Total flow requirement based on total energy dissipation, rep rate limited by 20MW

heat removal 60-10=50C rise typ. deltaT

TF Inner Leg Cooling

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Packing Fraction v. Javgv=10m/s, 4 holes,Tcu_max=100C

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

4.0 4.5 5.0 5.5 6.0

Javg (kA/cm^2)

fPacking

dZ=5.75mdz=7.5m

Temperatures at Outlet of TF Inner Leg

020406080

100120140160180200

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Time (sec)

Temp (C)

TW10

TC10

TCA

Typical T v. tTypical T v. tfPacking dependson J_avg and dZfPacking dependson J_avg and dZ

KCOOL model Possible x-section

CuCu

H20H20

AdiabaticAdiabatic

Machine Heat Removal

Wmg 4500 MGPgrid 200 MWtpulse 60 secWtotal 16500 MJPpulse 275 MWTmin water 10 degCTmax water 60 degCdelta T water 50 degCHeat removal rate 264 Watt/GPM-degCFlow 20833 GPMPcooling between pulse 20 MWTrep, min 825 secExisting water tank 33000 galHeat capacity 15846 J/gal-degCdelta T 32 degC

TFTR ratings (may not be available anymore TBD)…Water tank = 33000 gallons (adequate)Cooling power = 20MW (adequate)Component cooling = 3300 GPM (~ 1/6 of requirement)

Divertor Heat Removal

4” dia pipes are adequate for divertor supply/returnmanifolds (assume full power capacity on top and bottom)

Paux 38 MWfDiv 0.75 MWP_div_tot 28.5 MW#Sub-paths 2T_inlet 10 degCT_outlet 60 degCdT 50 degCHeat Transfer Rate 264 Watt/GPM-degCMass Flow 1080 GPM

6.81E-02 m^3/sFlow Velocity 10 m/sFlow Area 0.0068 m^2Hydraulic Dia 0.093 m

3.666 inReynolds Number 9.31E+05 N-sec/m^2Friction Factor 0.012Manifold Radius 0.5 mEff Path Length 0.79 mdP 0.72 psi

Power Supplies

Use PS at 15kA per PSS (continuous rating of SCRs)Rep rate limited to ~ 1200s min due to 3.25kA rms rating

FCPC Xfmr Thermal Response

35

45

55

65

75

85

95

0 5000 10000 15000 20000 25000 30000

Time (sec)

T (degC)

T_oil

T_winding

FCPC Cable Thermal Response

35

45

55

65

75

85

95

0 5000 10000 15000 20000 25000 30000

Time (sec)

T (degC)

Xfmrs OK(8 hrs)Xfmrs OK(8 hrs) 5 parallel 750MCM per PSS5 parallel 750MCM per PSS

~ 50 parallel 1000MCM cables req’d for 200kA-60s/1200s

Results (1)Ip [MA] vs. A

2.5

3.0

3.5

4.0

4.5

1.5 1.6 1.7 1.8 1.9 2.0

Ip [MA] vs. A

2.5

3.0

3.5

4.0

4.5

1.5 1.6 1.7 1.8 1.9 2.0

Bt [T] vs. A

0.5

1.0

1.5

2.0

2.5

1.5 1.6 1.7 1.8 1.9 2.0

Bt [T] vs. A

0.5

1.0

1.5

2.0

2.5

1.5 1.6 1.7 1.8 1.9 2.0

Paux [MW] vs. A

10

15

20

25

30

35

40

1.5 1.6 1.7 1.8 1.9 2.0

Paux [MW] vs. A

10

15

20

25

30

35

40

1.5 1.6 1.7 1.8 1.9 2.0

OH Flux [W] vs. A

1.0

1.2

1.4

1.6

1.8

2.0

2.2

1.5 1.6 1.7 1.8 1.9 2.0

OH Flux [W] vs. A

1.0

1.2

1.4

1.6

1.8

2.0

2.2

1.5 1.6 1.7 1.8 1.9 2.0

Results (2)Ip*Paux [MA*MW] vs. A

10

15

20

25

30

35

40

45

1.5 1.6 1.7 1.8 1.9 2.0

Ip*Paux [MA*MW] vs. A

10

15

20

25

30

35

40

45

1.5 1.6 1.7 1.8 1.9 2.0

Ip*A [MA] vs. A

4.0

5.0

6.0

7.0

8.0

1.5 1.6 1.7 1.8 1.9 2.0

Ip*A [MA] vs. A

4.0

5.0

6.0

7.0

8.0

1.5 1.6 1.7 1.8 1.9 2.0

P/R [MW/m] vs. A

10

15

20

25

30

35

40

45

1.5 1.6 1.7 1.8 1.9 2.0

P/R [MW/m] vs. A

10

15

20

25

30

35

40

45

1.5 1.6 1.7 1.8 1.9 2.0

ne*tau_E*T [10^19*keV/m^2] vs. A

0

2

4

6

8

10

1.5 1.6 1.7 1.8 1.9 2.0

ne*tau_E*T [10^19*keV/m^2] vs. A

0

2

4

6

8

10

1.5 1.6 1.7 1.8 1.9 2.0

Results (3) 1.50 1.60 1.65 1.70 1.75 1.80 1.90 2.00R0[m] 0.884 0.906 0.917 0.927 0.937 0.947 0.965 0.982A_100 1.500 1.600 1.650 1.700 1.750 1.800 1.900 2.000kappa 3.000 2.904 2.860 2.818 2.777 2.738 2.665 2.598delta 0.600 0.600 0.600 0.600 0.600 0.600 0.600 0.600qcyl 2.50 2.50 2.50 2.50 2.50 2.50 2.50 2.50Ip[MA] 3.022 3.675 3.902 4.038 4.119 4.150 3.986 3.708Bt[T] 0.838 1.194 1.367 1.523 1.669 1.801 1.977 2.087Router_TF 0.147 0.186 0.208 0.229 0.244 0.270 0.336 0.388drfw[m] 0.052 0.064 0.069 0.073 0.076 0.078 0.072 0.066Itf[Amp per turn] 102902 150351 174163 196193 217135 236932 264940 284622TF_packing 0.45 0.67 0.76 0.80 0.81 0.81 0.74 0.70J_TF_inner [A/m^2]1.23E+08 7.54E+07 6.10E+07 5.37E+07 5.20E+07 4.61E+07 3.66E+07 3.09E+07J_TF_outer [A/m^2]1.03E+07 1.50E+07 1.74E+07 1.96E+07 2.16E+07 2.38E+07 2.64E+07 2.84E+07Sigmax_TF [MPA] 32 43 47 49 53 51 42 36Taumax_TF [MPA] 73 77 75 72 74 66 44 31Flux_total 1.36 1.71 1.86 1.97 2.05 2.11 2.12 2.06Rinner_OH 0.162 0.200 0.223 0.244 0.258 0.285 0.351 0.403Router_OH 0.242 0.276 0.292 0.309 0.325 0.343 0.386 0.425J_OH[A/m^2] 1.16E+08 1.13E+08 1.14E+08 1.15E+08 1.11E+08 1.16E+08 1.43E+08 1.68E+08Sigmax_OH [MPA] 138 138 138 138 138 138 138 138Beta_N_thermal 3.00% 3.59% 3.53% 3.47% 3.41% 3.43% 3.55% 3.26%Beta_N_total 4.83% 4.73% 4.68% 4.63% 4.57% 4.52% 4.42% 4.32%Beta_N/Beta_N(A) 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0%Beta_T_alpha 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%Beta_T_nbi 11.7% 6.4% 6.1% 5.9% 5.5% 5.0% 3.6% 3.9%Beta_T_thermal 19.2% 20.3% 18.8% 17.5% 16.4% 15.6% 14.6% 12.2%Beta_T_total 30.9% 26.8% 25.0% 23.4% 21.9% 20.6% 18.2% 16.2%Beta_P 58.7% 74.9% 75.7% 76.6% 77.6% 80.1% 87.4% 84.4%xne[1/m^3] 4.04E+19 7.77E+19 8.24E+19 8.61E+19 8.97E+19 9.70E+19 1.18E+20 1.02E+20fGW 16.9% 24.8% 23.9% 23.3% 22.9% 23.8% 28.3% 24.7%fBS 36.8% 45.4% 45.3% 45.1% 45.1% 45.9% 48.8% 46.0%Tempavg[keV] 4.1 4.6 5.3 5.9 6.3 6.5 6.0 6.5HH98 (global) 1.30 1.30 1.30 1.30 1.30 1.30 1.30 1.30P_aux[MW] 12.0 22.5 27.4 31.5 35.0 37.8 38.0 36.8E_nbi[keV] 100 100 100 100 100 100 100 100Gamma_CD[10^20*A/W-m^2]0.059 0.066 0.075 0.083 0.089 0.091 0.1 0.1P_CD[MW] 11.99 22.08 22.10 22.07 22.14 23.46 28.51 23.00

Results (4)

NSTXNSTX NewNew

Conclusions

• Sweet spot ~ A=1.8 should be pursued

• Much work remains to - develop and prove out physics and engineering aspects of design- optimize water cooling aspects

• Highlighted challenges- TF bundle torsion and joint- large water flows- 200MW from grid- restoration of MG capability