29E42P
システムコードを用いた原型炉プラズマ設計領域のスコーピング研究	 
Scoping study of design windows of a tokamak DEMO reactor by using asystems code
中村 誠、飛田 健次、宇藤 裕康、坂本 宜照
Makoto NAKAMURA, Kenji TOBITA, Hiroyasu UTOH, Yoshiteru SAKAMOTO
原子力機構
JAEA
A current status of our scoping study of design
windows of a tokamak DEMO conducted under theBroader Approach is reported. One of highlights ofthe results is evaluation of an ‘inter-linked’ (IL)central solenoid (CS) [1] for inductive plasma
current Ip ramp-up in a tokamak reactor [2].
A CS function in a tokamak is inductive Ip
ramp-up. If the CS is designed to accomplish thisfunction, the CS size will be large to generate themagnetic flux swing sufficient for the inductive Ip
ramp-up. This leads to increase in the reactor sizeand construction cost. If non-inductive current drive
methods are employed, the CS and reactor sizes
will be reduced like the compact tokamak DEMO
SlimCS [1]. However, such methods have not been
demonstrated extensively in a tokamak plasma withthe medium or large aspect ratio and moderate
plasma performance.
A basic idea of the IL-CS concept is to wind aCS such that it is linked in toroidal field coils toachieve a larger amount of the magnetic flux swing
than of the conventional (C-) CS by increasing theCS cross section. The two CS configurations areshown in Fig. 1.
We made comparison of the magnetic flux
swings generated by the IL-CS and C-CS, ΦIL-CSand ΦC-CS, for the Ip ramp-up. We considered threecases characterized by the different reactor size. We
developed sets of design parameters of the C-CS
fusion reactors with the fusion power Pfus = 2 GWfor the three cases by using the systems code
TOPPER [3] and the TFC design code SCONE [4].
Sets of design parameters of the IL-CS reactors
were developed so that for each case (i) Rp, A, κ andq95 are equal to those of the corresponding C-CS
reactor and (ii) the IL-CS outer radius is equal to
RTF of the corresponding C-CS reactor. The sets ofthe reactor design parameters calculated aresummarized in Table 1. Superconducting strand
was Nb3Al, and the averaged magnetic fields andthicknesses of the C-CS and IL-CS, (BCS, ΔCS), were(12 T, 0.4 m) and (4 T, 0.2 m), respectively. We
have found, as shown in Table 1, that,• ΦIL-CS > ΦC-CS is expected for Rp < 8.0 m, and• ΦCS ≅ Φramp is expected for the IL-CS
configuration for Rp = 6.5 m while ΦCS < Φrampfor the C-CS configuration.
These results indicate that use the IL-CS
configuration can bring the Ip ramp-up only by theinductive way and the large amount of the flux
swing margin that can be used for Ohmic current
during the flat-top operation phase, compared to theC-CS.
[1]
[2]
[3]
[4]H. Utoh, et al., to be submitted elsewhere (2012).
M. Nakamura, et al., submitted to Plasma Fusion
Res. (2012).
K. Tobita et al., Fusion Eng. Des. 81, 1151
(2006).
H. Utoh, et al., J. Plasma Fusion Res. Ser. 9, 304(2010).
(a)CL

Conventional CS
TF coilVacuum vessel(b)Inter-linked CS

CLlarge RCS

small R CS

Fig.1 (a) Conventional and (b) inter-linked CS
configurations.
Table 1 Design parameters of three cases of C-CS andIL-CS fusion reactors.
Reactor case #12

3

Rcs,outer (m)Rtf (m)C-CS
1.702.90IL-CS
2.90
2.70

C-CS
2.20
3.94

IL-CS
3.94
3.74

C-CS
2.70
4.32

IL-CS
4.32
4.12

Bmax (T)Rp (m)
κAβN
q95
Bt (T)Ip (MA)
HHy2
Pfus (MW)

13.3
6.50
1.83
2.95
3.74
4.70
5.94
14.7
1.30
1888

<<<<<<5.53
13.7
1.21
1418

14.0
7.50
1.64
3.47
3.35
4.46
7.35
13.0
1.30
1921

<<<<<<6.98
12.3
1.23
1560

13.1
8.00
1.63
3.51
3.33
4.40
7.08
13.1
1.30
1881

<<<<<<6.75
12.48
1.24
1556

Φramp (Wb)

203

189

235

223

255

243

Φcs (Wb)

170

197

302

371

471

448

Φcs/Φramp

0.84

1.04

1.28

1.66

1.85

1.84