International West Lake Symposium on Fusion Plasma Physics 2011

Jinlin Xie on behalf of KTX teamDept. of Modern Physics, School of Physical Sciences

University of Science and Technology of ChinaHefei, Anhui, China

New possible RFP project in China

Keda Torus eXperiment (KTX)

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

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.

China’s energy consumption requirements

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

An early stellarator in China

Stellarator “LinYun”: designed in1965, capacitor bank energy: 800kJ plus ICRF heating

Tokamaks in China

SouthWestern Institute of PhysicsHL-2A at SWIP

Huazhong University of Science & TechJoint-TEXT at HUST

Institute of Plasma Physics Chinese Academy of Sciences EAST & HT-7 at ASIPP

University of Science and Technology of China (USTC)

Qinghua University ST: SUNIST

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

Tokamak RFP

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

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. ITERTITAN ITER

TITAN

ITER

Major radius(m) 3.9 6.2Minor radius(m) 0.6 2.0

Plasma current(MA) 18 15Toroidal field(T) 0.36 5.3

Energy-confinement time(s) 0.15 5.8Poloidal Beta 23％ 3%

Fusion Power(GW) 2.3 0.5Neutron wall load(MW/m2) 18 0.5

Present RFP experiments

RFX-Mod (Italy)RFX-Mod (Italy)R/a = 2 m / 0.46 mR/a = 2 m / 0.46 m

MST (UW-Madison)MST (UW-Madison)R/a = 1.5 m / 0.5mR/a = 1.5 m / 0.5m

Extrap-T2R (Sweden)Extrap-T2R (Sweden)R/a = 1.24 m / 0.18mR/a = 1.24 m / 0.18m

RELAX (Japan)RELAX (Japan)R/a = 0.5 m / 0.25mR/a = 0.5 m / 0.25m

RFX-Mod @ Italy• Plasma current~2MA, the biggest RFP device,

Active feedback control, high current operation MST @ U.S.

• One of the four major MCF devices, plasma current ~0.8MA, current drive & confinement improvement

Extrap-T2R @ Sweden• 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

RFX: self-organized Single Helical Axis state come with electron transport barriers

Recent achievements in RFP

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 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

Concept design of Keda Torus eXperiment

Major radius: 1.4 mMinor radius: 0.4 m

Aspect ratio 3.5

Wall thickness: 6 mm (stainless steel)1.5mm (copper shell)

Plasma current: 0.5 MA / 1MA

Plasma Pulse: 10 ～ 30 ms 100ms (with feedback)

Loop Voltage: 10 ～ 50 VPlasma

inductance: ～ 4 μHPoloidal flux: 5 V٠S

Te: 600 ～ 800 eVPlasma density (1 ～ 2) 1019m-3

Ohmic heating coils

Toroidal coilsEquilibrium coils

Modular shell: Stainless steel for vacuum chamber (6mm/2ms), plus one thin copper layer (1.5mm /20ms)

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

T2R C

oil system(s)

toroidal direction

polo

idal

dir

ectio

n

Active coils: twice the width of the sensor coils 4 (poloidal) x 16 (toroidal) positions 50% surface coverage

top

inboard

outboard

bottom

Br sensor coils 4 (poloidal) x 64 (toroidal) positionsfull surface coverage (limited acquisition)

343.125˚ 0˚ 16.875˚ 39.375˚ 61.875˚ 84.375˚

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

Reconnection in space physicsThe disk momentum transport problem

ITER & Tokamak related– RWM in high Beta; stochastic magnetic

field & active MHD control; high beta tokamak mode with low toroidal field

Fundamental issues in space & astrophysics– Dynamo, magnetic resonnection, anomalous ion

heating, momentum transport

Training talents for MCF program– Rich physics of RFP, easy operation, daily

running, direct impression of MCF research

Ohmic coils: minimize stray field

R(m)

The distribution of the poloidal magnetic field (Green circle: the cross section a=0.4mBlue dot circle: area occupied by plasma, with a radius of 0.3m )

Gauss

Collaborated with EAST team

Vacuum field of equilibrium coils (Bvertical)Equilibrium Magnetic Surface

Ip Li betap

Rmaxis

Rout Rgapi Rgapo

500 kA

1.33 0.36 1.42 m

1.398 m

2.4 mm

6.2 mm

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

2010 Oct, Int RFP workshop, USTC

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

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!