7th Asia-Paciﬁc Conference on Plasma Physics, 12-17 Nov. 2023 at Port Messe Nagoya

Density dependence of tokamak equilibria with consistent bootstrap current
and steady-state temperature proﬁle including burning and radiation loss
effects
Y. Masamoto1 , M. Furukawa1 , N. Aiba2 , M. Honda3
12Grad. Sch. Eng., Tottori University, Japan,
QST Naka, Japan
3
Grad. Sch. Eng., Kyoto University, Japan,
e-mail (speaker): d22t5006z@edu.tottori-u.ac.jp

The Te decreased as the ne was increased. The q proﬁle remained almost same, since the fractions of beam
driven and bootstrap currents to the total current weresmall. Figure 2 shows dependency of Pfus , βN and fBS
the central ne . Although Te decreased, Pfus , βN and fBS
increased as the central ne is increased almost linearly inthis density range.
1.4

121

100.6
0.4
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
ρ85
4.5
4
3.5
3q

0.8

0.2

AB
CAB
C

14Te/keV

ne/1020m-316A
B
C

1.2

2.56241.52100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
ρ

0.5Figure 1: Electoron dencity (left), electron temperatureand safety factor (right) proﬁles.
20.35

1.80.345

1.6

0.34

1.4

0.335

1.2

0.33

1

0.325

0.8
0.6

0.32

0.4

0.315

0.2

βN
fBS
Pfus

fBS

βN,Pfus/GW

ITER[1] construction has progressed and JT-60SA[2]device is now under integrated commissioning. Design
studies of DEMO have been conducted in Japan andoverseas. In Japan, JA DEMO concept was proposed in2014[3]. Its major radius is 8.5 m, the toroidal magnetic
ﬁeld is 5.94 T, the aspect ratio is 3.5, ellipticity is 1.65,
triangularity is 0.33, and the plasma current is 12.3 MA.
The target normalized beta βN = 3.4, the bootstrap current fraction fBS is around 60%, and the fusion power
Pfus is 1.5 GW level in steady-state operation.
In such design studies, the pressure proﬁle should beconsistent with steady-state density and temperature proﬁles of their transport equations, and the current density
should include bootstrap current consistent with the density and temperature proﬁles. Therefore we must comﬁrm, if such self-consistent equilibria with the parameters proposed in JA DEMO 2014 exist. However, transport properties of such burning plasmas is not fully understood. Therefore, our motivation in this paper is to ﬁnd
trends in the heat transport properties of burning plasmas.
Based on this motivation, we have utilized the integrated model GOTRESS+ code[4] that calculates an
MHD equilibrium of which the bootstrap current density
proﬁle consistent with temperature and density proﬁles,
where the temperature proﬁle satisﬁes steady-state transport equations of which transport coefﬁcients consistent
with the MHD equilibrium proﬁles. Therefore, we canobtain equilibria as consistent as possible for given density proﬁle, heating and current drive.
We plan to ﬁnd dependency and sensitivity of theconsistent equilibria and their ﬁgure of merits on limited number of controllable parameters by using theGOTRESS+ code. In the present study, the density dependence of the consistent temperature and safety-factor
proﬁles, Pfus , βN , and fBS is investigated. The electron
density ne was varied by 1.5×1019 m−3 at the center fora ﬁxed pedestal density proﬁle as shown in Fig. 1 (left).
The total current was given and ﬁxed to be Ip = 11.9
MA. The toroidal ﬁeld strength 5.95 T as well as thecross-sectional shape were ﬁxed. The heating input was
the neutral beam. If the sum of the beam driven and thebootstrap currents were less than the given total value,
an additional current with a given radial proﬁle was included. Note that the pedestal proﬁle was obtained by
the EPED1 model[5]. The Bohm/gyroBohm model wasused for the heat transport. The calculations were performed assuming dueterium, tritium, helium, and iron asion species. Consistently obtained electron temperature
Te and safety factor q proﬁles are shown in Fig. 1 (right).

1

1.1

1.2
1.3
ne0/1020m-3

0.31
1.4

Figure 2: Density dependence of fusion power, normalized beta and bootstrap current fraction.
Acknowledgement
M.F. and M.H. were supported by QST Research Collaboration for Fusion DEMO.
References[1] Y. Shimomura et al., NUCLEAR FUSION 39,1295 (1999), 17th IAEA Fusion Energy Conference,
YOKOHAMA, JAPAN, OCT 19-24, 1998.
[2] Y. Kamada et al., NUCLEAR FUSION 53, 104010(2013).
[3] Y. Sakamoto et al., in Proceedings of 25th IAEA
Fusion Energy Conference (St. Pertersburg, Russia,2014), FIP/3-4Rb.
[4] M. Honda, N. Aiba, H. Seto, E. Narita and N.
Hayashi, Nucl. Fusion 61 (2021) 116029 (13pp).
[5] P. B. Snyder et al., Phys. Plasmas 16, 056118 (2009).