24P111-P
Research on burn control of core plasma with the transport code
輸送コードを用いたコアプラズマ燃焼制御に関する研究
Yuya Miyoshi, Yuichi Ogawa, Makoto Nakamura
三善悠矢1, 小川雄一1，中村誠2
1

Graduate School ofFrontier Science, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8568, Japan
Japan Atomic Energy Agency, 2-166 Oaza-Obuchi-Aza-Omotedate, Rokkasyo, Kamikita, Aomori 039-3212
1
東大新領域 〒277-8568 千葉県柏市柏の葉5-1-52
日本原子力研究開発機構 〒039-3212 青森県上北郡六ヶ所村大字尾駮字表舘2-166

2For the fusion reactors or experimental devices, one will be required to control several plasma parameters,
like fusion power, heat flux, neutron flux, beta-value and so on. To control these parameters, many
diagnostics and actuators are needed, but in Demo reactors or commercial reactors, the attachable
diagnostics and actuators are limited because of the high heat or neutron flux. For these reasons, to realize
the fusion reactors, the construction of the reactor control logic is required. We are developing the burncontrol logic in the core plasma with a 1.5D transport code. In this article, we introduce the simulation
results on the control of the fusion power and the safety factor profile with the gas-puff and NBI.

1. Introduction
To operate the fusion reactors or fusion
experimental devices, controlling many plasma
parameters is required. One is required to keep
the plasma density, temperature, fusion power,presser, etc to the target value with taking many
constraints like the limitation of the heat flux intoaccount. For satisfying this requirement, thecombination of the diagnostics and actuators isvery important. It is, therefore, required toidentify the ideal combination of diagnostics andactuators and to construct the control logic[1-3].
In our research, the simulation of core plasma
control has been developed. The analysis of theplasma shape, position and vertical instability isshown in ref.4. In this article, we will introduce
the core plasma control simulation. Similar
analyses are done in some researchers; e.g., thecurrent drive simulation with the measurement ofcurrent profile peaking factor[5], the current driveand control simulation in ITER[6,7], the density
profile control analysis in ASDEX[8], and plasmaburn control simulation in JT-60U[9]. In most ofthese researches, they control one parameter with
one actuator. For the future reactors, however,controlling multiplex parameters with multiplex
actuators is needed. To do this, one must take theinteraction between the actuators into account. In
this article, we will show the control simulationof the fusion power and safety factor profile withgas-puff and NBI for the ITER like plasma,
aiming to achieve Q>5.
2. Fusion power control

The simulation is done with 1.5D transport code.
We control the fusion power with PID gas-puff
control. Here we adopt the ITER steady-state
operation mode. The main input parameters are asfollows:
Rp=6.3m, ap=1.75m,κ=1.8, δ=0.4
Ip=9MA, Bt=4.76T,
Pnbi=70MW, Enbi=1MeV,
where Rp, ap,κ,δ are the plasma major radius,
minor radius, elongation, triangularity, respectively,and Ip, Bt, Pnbi, Enbi are the plasma current, thetoroidal magnetic field, the power of NBI, theenergy of NBI, respectively. The transportcoefficients are below.
Dj=0.02/ne(1020m-3)
χj=0.08Te(kev)/ne(1020m-3)
The simulation result is shown in Fig. 1 and 2.

Fig 1. The blue, red and green solid lines arefusion power, gas-puff amount and NBI power
respectively, and green dashed line is target
fusion power.

Figure 1 shows the control of burning plasma withthe fusion power of about 350MW. Since the NBI
power is 70 MW, the achievement of Q > 5 plasma
is demonstrated. Figure 2 shows the minimum
q-value and its location. Since the location of theminimum q-value is in the region of r/a = 0.45, thereversed shear profile is observed. In addition, it isidentified that the safety factor becomes less than
1.5 between 60 sec and 180sec. It seems that somecurrent control is needed to avoid this instability.

Fig 2. The red line and blue line are minimum

q-value and r/a where q-value is minimum

3. Combination control
To avoid safety factor q<1.5, we increase NBI
power to 85MW, and decrease to 70MW slowly.
The simulation results are shown in Figs. 3 and 4.

Fig. 3. The blue, red and green solid lines arefusion power, gas-puff amount and NBI power
respectively, and green dashed line is target
fusion power.

Fig. 4. The red line and blue line are minimum

q-value and r/a where q-value is minimum

Figure 4 shows q>1.5 after 30 sec, and itmeans avoiding instability. At the same time,in Fig. 3, fusion power is maintained
constantly because gas-puff feedback isfaster than NBI decrease. Then, Q>5 isachieved without instability.
4. Summary and discussion
For the future reactors, the control of many
plasma parameters is indispensable. To
satisfy this requirement, the construction of
the ideal control logic with the combination of
the multiplex diagnostics and the multiplex
actuators is needed. In this article, we show
the example of the combination control
simulation. We control the fusion power andthe safety factor with gas-puff and NBI. The
fusion power is controlled by gas-puff with
the PID logic. Then, 85MW NBI is injected toavoid safety factor q<1.5 and controlled to70MW slowly, then we achieve Q>5. This
result shows the possibility that the large
NBI power is needed only in startup phase.
In this simulation, we assumed the ITER
steady-state operation mode. The analysis of
the Demo reactors or the commercial reactors
is future work. More detailed discussion of
the diagnostics is also needed. The
extrapolation of the diagnostics of theneutron will be available in demo orcommercial reactor, but plasma current orcurrent profile measurement will be difficult.
References[1] J.A.Snipes et al, Fusion Engineering andDesign 85 461-465 (2010)[2] B .Goncalves et al, Energy Conversion andManagement 51 1751-1757 (2010)[3] Y.Kamata, J. Plasma Fusion Res. Vol.86, No.9519-523 (2010) (in Japanese)[4] Y.Miyoshi et al, PFR. Vol6, 2405110 (2011)[5] H.Ouarit et al, Fusion Engineering and
Design 86 1018-1021 (2011)[6] J. Citrin et al, Nucl. Fusion 50 115007 (16pp)(2010)[7] R.V.Budny, PHYSICS OF PLASMAS 17042506 (2010)[8] A.Mlynek, et al, Nucl Fusion 51 043002 (10pp)(2011)[9] K.Shimomura et al, Fusion Engineering and
Design 82 953-960 (2007)