ARIES Systems Studies: ARIES-I and ARIES-AT type operating points C. Kessel Princeton Plasma Physics Laboratory ARIES Project Meeting, San Diego, December 15-16, 2009

Basic ARIES Design Point Matrix ARIES-I physics DCLL blanket ARIES-AT physics DCLL blanket ARIES-AT physics SiC blanket ARIES-I physics SiC blanket 1) Identify these operating points with systems code 2) Generate detailed physics and engineering analysis as necessary for each point 3) Refine systems code evaluations based on detailed analysis 4) Begin PMI, off-normal events, and other studies on these configurations

ARIES-I Final Report (original design had even higher B T ) Ip = 10.2 MA B T = 11.3 T (B T coil = 21 T) R = 6.75 a = 1.5 κ(95) = 1.8 (1.6) δ(95) = 0.7 (0.5) β N = 3.15 P(ICRF) = 100 MW P(LH) = 5 MW η CD = 0.33 f bs = 0.68 = 1.45x10 20 /m3 v,n = 20 keV f rad = 0.5 q(0) = 1.3 q 95 = 4.5 li = 0.74 b/a| n=0 = 0.6 Z eff = 1.7 f rad,cyc = 92% τ E = 2.5 s β p = 2.18 H 89P = 2.25 (τ E,89P = 1.11 s) H 98y2 = 1.45 (τ E,98y2 = 1.72 s) τ p * ~ 3-4 τ E

Starlite Study, Systems Code update of ARIES-I Ip = 12.6 MA B T = 9.0 T (B T c = 16 T) R = 8.0 a = 2.0 A = 4.0 (rather than 4.5) κ = 1.8 (1.6) δ = 0.7 (0.5) β N = 2.88 P CD = 236 MW η CD = 0.28 f bs = 0.57 = 1.45x10 20 /m3 q(0) = 1.3 b/a| n=0 = 0.6 τ E = 2.5 s H 89P = 1.7 H 98y2 = 1.23 τ p * ~ 10 τ E Starlite physics regimes was an attempt to get the 4 tokamak physics regimes on an equal footing to examine the COE versus fusion power density and recirculating power; 1) first stability,2) pulsed, 3) reversed shear, and 4) second stability B T c < 16 T f bs from same model τ p */τ E = 10 A (R/a) = 4.0 H 89P for all cases

In order to “reconstruct” an ARIES-I we need to make some decisions….. The very high field at the magnet facilitated high B T in the plasma, so that low β N could be accommodated  what is the maximum B T coil we want to assume We must also address the j SC, the new formula in the systems code fails for B t coil > 18 T for Nb3Sn – The curves in the systems code paper do not jive with the j SC formula in the code – What are we assuming for j SC vs B relative to short sample values, which are the highest values in the literature, versus j SC eff which is over the conductor pack, versus j total over the whole TF coil cross- section We need to revisit the likelihood of the ARIES-like SC magnet projections made 20 years ago – ITER TF coil (Nb3Sn) uses j total = 14 MA/m 2 at 11.3 T – ARIES algorithm gives j total = MA/m 2 at 11.3 T

J total versus B t coil from ARIES-I report, similar curves shown in ARIES-II/IV report J total is the current density over the whole coil, SC + stabilizer + insulator + coolant + structure ARIES-AT

Nb3Sn SC operating points ITER TF: (full size magnets) j SC = 650 MA/m 12 T and 4.2 K j eff = MA/m 12 T and 4.2 K j total = 14 MA/m 12T and 4.2 K Nb3Sn short samples? (accelerator development) j SC = 3000 MA/m 12.4 T and 4.2 K j eff = 1000 MA/m 12.4 T and 4.2 K Processed strand was 10 km long Gourlay et al, 2003 and Caspi et al 2005 Accelerator magnet development is targeting manufacturable coils with long strand lengths and low costs, BUT their coil geometry may affect their solutions and our ability to “lift” their results Should we be choosing HTSC as our basis?

New search for ARIES-I plasma operating points within engineering constraints 2.5 < β N < 3.3, first stability regime, no kink wall required 6.0 T < B T < 10 T, using new magnet algorithm with different j SC lim 3.5 < q 95 < < n/n Gr < 1.3, going above Greenwald density 10 < Q < < R < 9.0 A = 4.0  try others? f Argon = 0.15% κ = 1.8 & 2.2 δ = 0.7 (0.5) τ p */τ E = 5-10 η CD = 33%  use lower values η aux = 67% f rad,div = 0.75 & 0.90 Nb3Sn TF/PF coils  try HTSC? 2 blanket types: SiC and DCLL DCLL Δ FW = m Δ blkt = 0.50 m Δ VV = 0.31 m Δ shld/skel = xIn( /3.3) m η th ~ 42%, P pump ~ 0.04xP fusion SiC Δ FW = 0.0 m Δ blkt = 0.35 m Δ VV = 0.40 m Δ shld/skel = xIn( /3.3) m η th ~ 55%, P pump ~ 0.005xP fusion

Conservatism in searching for solutions for ARIES-I and AT design points We do NOT want to assume very optimistic parameters, but rather we want to find solutions that do not require extreme assumptions H 98 ~ 1.3 is better than 2.0 f div,rad ~ 75% is better than 95% q peak,div out < 8 MW/m2 is better than 15 MW/m2 B t coil < 13 T is better than 18 T n/n Gr < 1.0 is better than 1.4 An so on…….. Systems code solutions that follow: DCLL or SiC κ= 1.8 or 2.2 ARIES-I or ARIES-AT f div,rad = 0.75 or 0.90

Solutions for lowest R, κ= 1.8 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 200 MW, H 98 < 1.5, q div peak < 12 MW/m 2 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus κ= 1.8, SiC, η th ~ 0.55 No κ= 1.8 solutions for DCLL with f div,r = 0.75 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus κ= 1.8, DCLL, η th ~ 0.42

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 200 MW, H 98 < 1.5, q div peak < 12 MW/m 2 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus κ= 2.2, DCLL, η th ~ 0.42 Solutions for lowest R, κ= 2.2

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 200 MW, H 98 < 1.5, q div peak < 12 MW/m 2 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus κ= 2.2, SiC, η th ~ 0.55 Solutions for lowest R, κ= 2.2

Search for ARIES-AT plasma operating points within engineering constraints 4.0 < β N < 6.0, advanced stability regime, kink wall required 4.5 T < B T < 8.5 T, using new magnet algorithm with different j SC lim 3.2 < q 95 < < n/n Gr < 1.3, going above Greenwald density 15 < Q < < R < 8.0 A = 4.0 f Argon = 0.15% κ = 1.8 & 2.2 δ = 0.7 (0.5) τ p */τ E = 5-10 η CD = 33% η aux = 67% f rad,div = 0.75 & 0.90 Nb3Sn TF/PF coils 2 blanket types: SiC and DCLL DCLL Δ FW = m Δ blkt = 0.50 m Δ VV = 0.31 m Δ shld/skel = xIn( /3.3) m η th ~ 42%, P pump ~ 0.04xP fusion SiC Δ FW = 0.0 m Δ blkt = 0.35 m Δ VV = 0.40 m Δ shld/skel = xIn( /3.3) m η th ~ 55%, P pump ~ 0.005xP fusion

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 100 MW, H 98 < 1.8, q div peak < 12 MW/m 2 κ= 1.8, DCLL, η th ~ 0.42 One solution for f div,r = 0.75 Solutions for lowest R, κ= 1.8 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus κ= 1.8, DCLL, η th ~ 0.42

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 100 MW, H 98 < 1.8, q div peak < 12 MW/m 2 κ= 2.2, DCLL, η th ~ 0.42 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 100 MW, H 98 < 1.8, q div peak < 12 MW/m 2 κ= 1.8, SiC, η th ~ 0.55 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus

f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus P elec = 1000 MW, P aux < 100 MW, H 98 < 1.8, q div peak < 12 MW/m 2 κ= 2.2, SiC, η th ~ 0.55 f div,r RBtBt IpβNβN qn/n Gr QH 98 P aux f bs NwNw P fus

ARIES-Iκf div,r R, mB T, T DCLL SiC SiC DCLL DCLL SiC SiC ARIES-AT DCLL DCLL SiC SiC DCLL DCLL SiC SiC

Comparison of kappa = 1.8 and 2.2 for DCLL blanket and ARIES-AT plasma

ARIES-I plasmas, TF coil solutions, what is TF limit at the coil? At TF coil At plasma At TF coil

Results What should our magnet basis be, the same for all 4 designs or a near term and an aggressive solution? We can see the importance of radiated power in the divertor, but this could also be a change in the power scrape-off width which is also an uncertain parameter Higher plasma elongation can provide smaller devices, but more importantly it enlarges the operating space. This requires a stabilizer in the blanket, should we have a high and a low elongation? In all cases, the DCLL is inferior to the SiC blanket/shield approach, but the ferritic steel is near term and the SiC is long term, which seems like a good approach