International West Lake Symposium on Fusion Plasma Physics 2011
New possible RFP project in China
Keda Torus eXperiment (KTX)
Jinlin Xie on behalf of KTX team
Dept. of Modern Physics, School of Physical Sciences
University of Science and Technology of China
Hefei, Anhui, China
Outline
 Motivation of the new RFP program in China
– Energy diversity: Fusion is necessary for China
– Fusion diversity: Toroidal Alternate Configuration
 The KTX program in USTC
– The emergence of KTX
– The KTX concept design
– The Goals and Scientific Issues for KTX
China Tops U.S. in Energy Use
“Asian Giant Emerges as No. 1 Consumer of Power, Reshaping Oil Markets,
Diplomacy.”
-The Wall Street Journal JULY 18, 2010
China’s energy consumption requirements





Coal: 70%
Oil: 20%
Hydroelectric sources: 6%
Natural gas: 3%
Nuclear power: 1%
We need an effort to
diversify our energy supplies!
Nuclear fusion — the process that powers the sun,
offers an environmentally benign, intrinsically safe
energy source with an abundant supply of low-cost
fuel.
Diversity during the early days in China fusion progam
(starting from 1958):
 Z pinch, Ө pinch, FRC, reversed field pinch
 Focus, mirror device
 Stellarator
 Tokamak
Stellarator “LinYun”: designed
in1965, capacitor bank energy: 800kJ
plus ICRF heating
An early stellarator in China
Tokamaks in China
Institute of Plasma Physics Chinese Academy of Sciences
EAST & HT-7 at ASIPP
SouthWestern Institute of Physics
HL-2A at SWIP
Huazhong University of Science & Tech
Joint-TEXT at HUST
Qinghua University
ST: SUNIST
University of Science and
Technology of China (USTC)
Current Fusion research platforms in China
Currently, four Tokamaks are running in ASIPP, SWIP
and HUST respectively. Fusion program in China is
focusing on Tokamak research. The tradition of
diversified fusion research has been lost!
China needs RFP research program
 It is not as yet clear which configuration will ultimately lead
to the most attractive fusion reactor
– Diversity is part of the nature, so is fusion research.
–
Ancient Chinese philosophy “Let a hundred schools of thought contend” (BC 770)
 Five scientific and technical research areas
–
–
–
–
Burning Plasmas in ITER
Creating Predictable, High-performance, Steady-State Plasmas
Taming the Plasma-Material Interface
Harnessing Fusion Power
– Optimizing the Magnetic configuration
 No related projects (issue 5th) have been launched in China
fusion program
Ref: Report of the Research Needs Workshop (ReNeW), Bethesda, Maryland – June 8-12, 2009;
Report of the FESAC toroidal alternates panel, November 26, 2008
Reversed Field Pinch: an important toroidal alternate concept
Three major configurations of MCF
 Stellarator: magnetic field is generated totally by the external coils
 Tokamak: magnetic field is generated primarily by the external coils
 RFP: magnetic field is generated primarily by the plasma current
RFP
Tokamak
Main advantages of RFP: Reversed Field Pinch

Small externally applied field:

the use of normal magnets, high engineering beta, high mass-power-density,
efficient assembly

The safety factor q<1, higher helical twist, enhanced magnetic shear

Large plasma current density: Ohmic heating for a burning plasma

Fascinating phenomena of magnetic self-organization and nonlinear plasma physics:

test bed for the understanding derived at high field, good platform to investigate the
transport, link between the fusion energy science and astrophysics
MST, John Sarff, 2010 USTC Hefei workshop
TITAN an RFP reactor 1990 VS. ITER
TITAN
ITER
TITAN ITER
Major radius(m)
3.9
6.2
Minor radius(m)
0.6
2.0
Plasma current(MA)
18
15
Toroidal field(T)
0.36
5.3
Energy-confinement time(s)
0.15
5.8
Poloidal Beta
23％
3%
Fusion Power(GW)
2.3
0.5
Neutron wall load(MW/m2)
18
0.5
Present RFP experiments

RFX-Mod @ Italy
•

RFX-Mod (Italy)
R/a = 2 m / 0.46 m
Extrap-T2R (Sweden)
R/a = 1.24 m / 0.18m
MST @ U.S.
•

MST (UW-Madison)
R/a = 1.5 m / 0.5m
RELAX (Japan)
R/a = 0.5 m / 0.25m
One of the four major MCF devices, plasma current
~0.8MA, current drive & confinement improvement
Extrap-T2R @ Sweden
•

Plasma current~2MA, the biggest RFP device,
Active feedback control, high current operation
Active feedback control of the MHD modes
Relax @ Japan
•
Smale aspect ratio R/a~2
MST: improved confinement achieved via
modification of the current profile
Recent achievements in RFP
RFX: self-organized Single Helical Axis
state come with electron transport barriers
The RFP proposal in USTC
Keda Torus eXperiment (KTX)
 In USTC, We have kept fusion research, small-scale but steadily
growing, for almost forty years
– Tokamak physics and diagnostic
– Fundamental research in small devices: magnetic reconnection experiment,
chaos, turbulence…
– Space plasma research: data analysis and numerical simulation of
reconnection phenomena…
– Theory and numerical simulation: tearing mode, kink mode
 RFP naturally fits our current status
– The diversity of Chinese fusion research
• KTX will not only address the relative important scientific issues of Tokamak,
but also improve the understanding of toroidal confinement in general
– The richness of physics: dynamo, magnetic self organization, RWM
– Training of fusion talents is the priority of university
• The easy operation, compared with Tokamak; daily running
The KTX project is a nature extension of China MCF program!
The former RFP research in China
 Construction from 1985
running from 1989
Shutdown in 1997
 R=0.48m, a=0.1m
air core
 Al shell: d=1cm
stainless steel liner:
d=0.4mm
 plasma pulse < 2ms,
Ip~150kA(max)
Te~100eV
The first RFP device in China :SWIP-RFP
Concept design of Keda Torus eXperiment
Major radius: 1.4 m
Minor radius: 0.4 m
Ohmic heating coils
Aspect ratio 3.5
6 mm (stainless steel)
Wall thickness: 1.5mm (copper shell)
Equilibrium coils
Toroidal coils
Plasma current: 0.5 MA / 1MA
10～30 ms
Plasma Pulse:
100ms (with feedback)
Loop Voltage: 10～50 V
Plasma inductance: ～4 μH
Poloidal flux: 5 V٠S
Te: 600～800 eV
Modular shell: Stainless steel for vacuum
chamber (6mm/2ms), plus one thin copper
layer (1.5mm /20ms)
Plasma density (1～2) 1019m-3
Active control configuration in KTX
 RWM control methods
– thick layer with good conductivity, act as an ideal conductive shell
– Rotation to suppress the RWM mode; need to control the plasma rotation or metal
wall rotation
– Active feedback with External coils: open loop & closed loop
poloidal direction
343.125˚
0˚
16.875˚
outboard
bottom
inboard
top
Br sensor coils
4 (poloidal) x 64 (toroidal) positions
full surface coverage (limited acquisition)
39.375˚
61.875˚
84.375˚
T2R Coil system(s)
toroidal direction
Active coils:
twice the width of the sensor coils
4 (poloidal) x 16 (toroidal) positions
50% surface coverage
The unique features of KTX
 The advanced RFP device
– Significant parameters
– advanced real-time feedback control
– Thin shell: close proximity to the plasma
• Linear stability for m=0 tearing could be critical (sensitive to wall proximity)
– Optimized aspect ratio for the realization of SHAs (single helical mode),
also good for the research of scaling of RFP confinement
– Optimized coil configuration for potential research of OFCD & PPCD
– Stainless steel inwall: good if accommodates advanced plasma-facing
materials, e.g., lithium
– Part of the Vacuum chamber can be moved out: to ensure the maximum
accessibility to interior
The Goals and Scientific Issues for KTX
 Fundamental issues in space & astrophysics
RWM control
High Beta
confinement
Dynamo
– Dynamo, magnetic resonnection, anomalous ion
heating, momentum transport
 ITER & Tokamak related
Magnetic
reconnection
RFP
research
Magnetic
helicity &
turbulence
– RWM in high Beta; stochastic magnetic
field & active MHD control; high beta
tokamak mode with low toroidal field
Current drive
Anomalous
ion heating
 Training talents for MCF program
Momentum
transport
Reconnection in space physics
– Rich physics of RFP, easy operation, daily
running, direct impression of MCF research
The disk momentum
transport problem
Ohmic coils: minimize stray field
Collaborated with EAST team
Gauss
R(m)
The distribution of the poloidal magnetic field (Green circle: the cross section a=0.4m
Blue dot circle: area occupied by plasma, with a radius of 0.3m )
Vacuum field of equilibrium coils (Bvertical)
Equilibrium Magnetic Surface
Ip
Li
betap Rmaxis Rout
Rgapi
Rgapo
500 kA
1.33
0.36
2.4
mm
6.2
mm
1.42 m
1.398
m
The milestones of KTX project
 We have tried to seek an appropriate experimental platform for high-temperature
plasma research for almost 10 years.
– Spherical Tokamak, Stellarater(CHS), FRC, RFP
 2009 Nov, Atalanta, U.S.
– discussion about the possibility of RFP with Piero and Weixing during the APS meeting
 2010 April, RFX, Padova, Italy
– the 14th Workshop of the International Energy Agency Implementing Agreement on RFP
– The concept design of KTX (thick shell)
– The first literation of USTC RFP project, with RFX group, John (MST), Sadao (Relax), James
(Extrap-T2R) and Weixing, Chijin.
 2010 August, MST, Madison, U.S.
– The name of USTC RFP project: KTX
– The second literation of USTC RFP project, with MST group, Weixing, Chijing and RFX members
(via video conference): change from thick shell to thin shell
 2010 October, USTC, Hefei, China
– USTC international RFP workshop, including MST, RFX, Relax members
 2011 June, USTC, Hefei, China: issues of
construction, with MST, Relax & EAST group
2010 April, Padova, Italy
the 14th Workshop of the IEA on RFP
The RFP family is growing and thus
welcomed a delegation from USTC, one of the
top Chinese universities, is planning to
construct a new RFP device. The new RFP will
contribute towards meeting the need for a
strong research program on alternate concepts,
which is considered essential for the success of
the Chinese domestic fusion programme in the
ITER era.
2010 August, MST, Madison, U.S
2010 Oct, Int RFP workshop, USTC
Future of KTX
 天时
– Right time, ITER era
 地利
– Right place, USTC, Hefei, close to other MCF facilities
 人和
– Human harmonic environment
– Support from international RFP community and
domestic MCF community
Conclusion: KTX must have a bright future
Thanks, and Welcome to USTC!