MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

J.H. SchultzM.I.T. Plasma Science and Fusion Center

NSO PAC 2 Meeting

January 17-18, 2001

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

1. IPB98(y.2) Scaling

- reduced 2.0 m Wedged FIRE from Q=10 to Q=5 at 10 T

- parametric study explores bucked/wedged option for cost/mission improvements

2. Equalization of TF/CS "burn times"

- optimization of TF/CS interface

3. Scan of A, Bt for "Fixed Mission"

- Margin=2 and Margin=1

4. Detailed Cost vs. Ro Sensitivities

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

τ κEIPB p o t e avH y I R a B AMU n P980 93 1 39 0 58 0 15 0 78 0 19

200 41 0 690144 2= −. ( , ) . . . . . . . .d i

Physics EngineeringH(y,2)=1.1 Pw < 3 MW/m2

αN=0.2 Thot,TF < 373 K

βN =0.016 Thot,CS < 300 K

qlim = 3.104

τp∗/τΕ = 6

fGreenwald< 1

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

(1) TF/OH interface optimization

tburn,TF = tburn,OH (TF/OH interface optimum for fixed Ro

Subtract 3 s from TF flattop for heating

e.g. 24.5 s flattop = 24.5 s I flattop = 3 s heat + 21.5 s burn

No scaling of theat with plasma parameters

(2) Minimum Ro for "Mission Margin"

Mission: Long-pulse α-dominated plasmas

Margin=2: Q>=10; tflattop/max(τE, τp*, τJ) >= 2

Margin=1: Q>=5; tflattop/max(τE, τp*, τJ) >= 1

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Instead of fixing Ro and varying A

Vary Ro and A, while holding Margin=1,2

Margin=min(Pα/Pheat, tflattop/τJ)

3 Variations:

1) Minimum Ro(fixed A,B)with M=min(Pα/Pheat, tflattop/τJ)

2) Minimum Ro(fixed A, Bvariable @ low A); M=Const

3) Minimum Ro(fixed A,B, f(q) @ high B); M=Const

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Alpha margin=Time margin=2 at optimum A=2.0/0.525

Rapid rise in time margin and heating margin off optimum A

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Reduced Mission: M=1, Q=5,tburn/τJ=1

R o,min = 1.59 m at Bt=11.5 T & A=(2.0/0.525)=3.8095

Bt=11.5 T for A=3.8

Bt=10.5 T for A=3.6

R(low A) nonlinear, but not pathological

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Ro (m) grows pathologically at high

Bt and qlim=3.1

Well-behaved if M=2,Q=10,t/τJ=2

(qlim > 3.1 at Bt>Bt,opt)Romin=1.86 m, A=3.8

Romin (A=3.6) = 1.925 m

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Romin = 1.86 m@

Bt=11.5, A=3.8

Ro (m) pathological at

low A

Cured by lowering Bt;

Q=10, M=2

(no effect on Romin)

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

M2:Minimum Cost =$1.06 B @ Ro= 1.86 m, A=3.8, Bt=11.5 T

- M2 < $1 B, if phase auxiliary power

M1:Minimum Cost = $0.92 B @ Ro=1.59 m, A=3.8, Bt=11.5 T

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Vary Ro; Bt=11.5 T, A=3.8,

qL=3.1, not fixed mission

$/Ro Sensitivity = 1.01

$/Ro: Paux, I&C = 0

Magnets=1.64

Basic Machine=1.25

Buildings=1.14

MIT Plasma Science and Fusion CenterFusion Technology & Engineering Division

Ro can be reduced to 1.86 m and retain M=2 mission

Mission reduction x 2 allows reduction of Ro to 1.59 m (1st order!)

Margin=2 mission requires lowering B @ A<3.5 or q @ B>13 T

d$/dR = 1: Machine sensitivity ~ 1.25 + nearly fixed costs

Recommendation: Reduce Ro to 1.87 m, Day 1 RF = 10 MW

Achieve all cost/mission objectives: Q=10, τflat/τJ=2, Cost<$1 B

Historic first: A noncatastrophic reduction in NSO Ro