physics rationale and engineering design of keda torus
TRANSCRIPT
6th US-PRC Magnetic Fusion Collaboration WorkshopSan Diego, July 10-12, 2012
Wandong Liu, on behalf of KTX team
School of Physical Sciences University of Science and Technology of China
Physics Rationale and Engineering Design of Keda Torus eXperiment
– Institute of plasma physics – South western institute of physics– Huazhong University of Science and Technology
– University of Wisconsin at Madison, U.S.– Consorzio RFX, Padova, Italy– Kyoto Institute of Technology, Japan– University of California Los Angles, U.S.– University of Saskatchewan, Canada
Collaboration with:
A new RFP program started in China
The new reversed field pinch(RFP) program in China, Keda Torus eXperiment (KTX)officiallystarted by the Ministry of Science and Technology, in the framework of the ITER domestic program
The duration of the program is 3 years, starting from the end of last year for design and construction of the machine (2012-2014)
The University of Science and Technology of China (USTC) will provide a new building to accommodate KTX device
Reversed Field Pinch: an important alternate toroidal concept
Tokamak RFP
Three major configuration of MCFStellarator: 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
Main advantages of Reversed Field PinchSmall externally applied field:
the use of normal magnets, high engineering beta, high mass-power-density, efficient assembly
Large plasma current density: Ohmic heating for a burning plasma
Fascinating phenomena of 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
Diversified fusion research recovered
TokamakHL-2A @ SWIP
TokamakJ-TEXT@HUST
Spherical TokamakSUNIT @ THU
TokamakEAST & HT-7 @ IPP
ChengduWuhan
Beijing
4 tokamaks (EAST/HT-7/HL-2A/J-TEXT)a small spherical tokamak (SUNIST)a reversed field pinch (KTX)
RFP KTX @ USTC
Hefei
The former RFP research in China
Construction from 1985 running from 1989Shutdown in 1997
R=0.48m, a=0.1mair core
Al shell: d=1cmstainless steel liner: d=0.4mm
plasma pulse < 2ms, Ip~150kA(max)Te~100eV
The first RFP device in China :SWIP-RFP
Present RFP experiments
RFX-Mod (Italy)R/a = 2 m / 0.46 m
MST (UW-Madison)R/a = 1.5 m / 0.5m
Extrap-T2R (Sweden)R/a = 1.24 m / 0.18m
RELAX (Japan)R/a = 0.5 m / 0.25m
RFX-Mod @ Italy• plasma current~2MA, the biggest RFP device, active
feedback control, high current operationMST @ U.S.
• plasma current ~0.8MA, current drive & confinement improvement
Extrap-T2R @ Sweden• active feedback control of the MHD modes
Relax @ Japan • small aspect ratio R/a~2
MST: improved confinement achieved via modification of the current profile
RFX: self-organized Single Helical Axis state come with electron transport barriers
Recent achievements in RFP
Keda Torus eXperiment (KTX) in USTC
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!
Main parameters of KTX
Major radius 1.4 m
Minor radius 0.4 m
Thickness of vacuum shell (SS) 6 mm (τ ~ 2ms)
Thickness of conductive shell (copper) 1.5 mm (τ ~ 20ms)
Plasma current 0.5MA (Phase I), 1.0 MA (Phase II)
Pulse length 30 ms (Phase I), 100 ms (Phase II)
Loop voltage 10~50 V
Plasma inductance ~ 4 μH
Total magnetic flux 3 ~ 5 V٠S
Electron temperature 600 ~ 800 eV
Plasma density ~1019 m-3
Maximum toroidal field 7000 Gauss
Ohmic Coil
Equilibrium Coil
Toroidal Coil
The structure of KTX
KTX has modular shell structureThin simple modular shell structure: thin stainless steel shell(6mm thick, 2ms penetration time) and copper shell (1.5mm, 20ms)– close proximity to the plasma– available active controls, e.g., MHD or PPCD & OFCD – potential research for advanced plasma-facing materials, e.g., lithium
Double-C structure– ensure an excellent accessibility to the internal space
Copper shell
vertical gaps
horizontal gapStainless steel shell
vertical gaps
0 1J rB a
α
μ λ⎡ ⎤⎛ ⎞= = −⎢ ⎥⎜ ⎟
⎝ ⎠⎢ ⎥⎣ ⎦
The modeling of KTX performance
collaborated with Prof. John Sarff
500 kA ramped mode
Simplified electrical circuit model
z zW V I V I Pt θ θ Ω
∂= + −
∂
Current profile: Alpha model
Design for KTX Ohmic coils
Ohmic coils are grouped into 8 sections. The parameters of ohmic coils are optimized to minimize the stray field in the chamber.
contributed by Binjia Xiao & EAST team
The parameters of Ohmic coils
The mutual inductance of Ohmic coils
Design for equilibrium of KTX
Similar to the configuration of RFX, the equilibrium coils of KTX are divided into eight sections, which connect to the corresponding Ohmic coil sections in parallel.
contributed by Binjia Xiao & EAST team
The parameters of equilibrium coils
Design of power supplies (capacitor banks)
Power supply for the toroidal coils
The current waveforms
C1
40k V3m F
C2
15k V50u F
TFcoil_L12m H
TFcoil_R
150m Ohm
D1
TF Coil
C3
450 V1 F
TH1TH2
C1
50k V1.2m F
Loh18.4m H
M96u H
Lplasma3.4u H
Rplasma30u Ohm
D2 Roh9.2m Ohm
C26m F
25k V
TH1
D3
C3
5k V0.15 F
D1
Power supply for the Ohmic coils
contributed by Dr. Peng Fu & EAST team
Design of KTX machine
Fully design for KTX machine, global shape, vacuum chamber, supporting structure, assembly strategy, analysis…contributed by Dr. Yuntao Song & EAST team
KTX Schedule
Laboratory building and KTX hall
30×20×16m3
KTX is open for international collaboration
Madison, July 2010
2010 Oct, USTCRFX, April 2010
June 2011, USTC
SummaryThe features of KTX:– thin simple modular shell structure: good proximity, possible
plasma facing material research, easy active control, for PPCD & OFCD research; for single helicity mode research …
– double C structure for easy accessibility– capacity for tokamak operation (low toroidal B and q value)
The mission of KTX:– contribute to the development of the RFP fusion concept– contribute to fusion science and to explore the similarity (or
contrast) to the tokamak configuration– general plasma science (dynamo, reconnection, …)– education and training of fusion scientists
Future of KTX in USTC天时(right time)
– ITER era
地利(right place)
– USTC, Hefei, Center for MCF research in China
人和( harmonic human environment)
– Support from international RFP community and Chinese MCF community
Conclusion: KTX must have a bright future
Thanks, and Welcome to USTC!