Introduction of 6 th Steady State Operation ITPA Topical Group Meeting X.D. ZHANG

Introduction of6th Steady State Operation ITPA Topical Group Meeting

X.D. ZHANG

8-10 November, 2004IST, Lisbon, Portugal

66thth SSO ITPA Meeting SSO ITPA Meeting

Participants (28/10/04)

US

Tim Luce [email protected]

Peter Politzer [email protected]

Ron Prater [email protected]

Roger Raman [email protected] Wilson [email protected]

EU

Claude Gormezano [email protected]

Rob Akers [email protected]

Alain Becoulet [email protected]

Gerardo Giruzzi [email protected]

Didier Moreau [email protected]

JM Noterdaeme [email protected]

George Sips [email protected]

Angelo Tuccillo [email protected]

mailto:[email protected]








New membership

EU: A.Becoulet, C.Gormezano, A.C.C.Sips, A. Tuccillo

Japan: S.Ide, A.Fukuyama, K. Hanada, T.Suzuki, Y.Takase,

Y.Nakamura

RF: V.Kulygin,V.Vdovin, A.Zvonkov

US: C.Philips, P.Bonoli, C.Forest, W.Heidbrink, R.Prater China: X.Gong, X. Ding, X. Zhang, X.Song, J.Luo

Korea: K.I.You, Y.S.Na, J.M.Kwon

ITER: T.Oikawa

up to 9 November 2004

Chair&co-chair: C. Gormezano & S. Ide

after 9 November

Chair&co-chair: A.C.C. Sips & S. Ide


Participants (28/10/04)

Japan

Shun Ide [email protected]

Kazauaki Hanada [email protected]

Yukio Nakamura [email protected]

Hiroschi Idei [email protected]

Yuichi Takase [email protected]

Takahiro Suzuki [email protected]

Atsushi Fukuyama [email protected]

China

Xiaodong Zhang [email protected]

ITER

Toshihiro Oikawa [email protected]


Charter for the: Steady-State Operation Topical Group

Explore the potential for achieving integrated scenarios for steady state operation in a burning plasma experiment:

• Scenarios for steady-state operation and maximising fusion energy produced

• Control systems (NB, ICH, ECH, LH, fuelling, pumping, ……• Applicability, feasibility and compatibility of heating and current

drive, fuelling, particle exhaust and angular momentum injection systems, for integrated operation in ITER.

• Steady state burning plasma conditions and techniques for current profile, density, and performance control (beta, fusion power….).


S. Ide: IAEA Highlights on Steady State scenarios

T. Luce: IAEA Highlights on Hybrid scenarios

Joint meeting with Transport Group on Joint experiments

(SSOEP1 & SSOEP2): achieved results

JT-60U (S. Ide)

AUG (G. Sips)

DIII-D (T. Luce)

JET (X. Litaudon)

Joint meeting with Transport Group on Joint experiments

(SSOEP1 & SSOEP2): proposals for new experiments,

fill in the bullets


Heating & Current Drive

R. Prater: IAEA Highlights on Heating &CD

H. Idei: Initial results on ECCD hardware experiments on TRIAM-1M

R. Prater: Status report on ECCD code benchmarking

E Joffrin: IAEA Highlights on Control Issues

D. Moreau: Control of ITBs on JET

T. Suzuki: real time control of j(r) in JT-60U

Joint meeting with Pedestal Group

G. Sips: Pedestal issues in Steady state and hybrid scenarios


(distance between the two separatrices at the midplane of diverted plasmas) organised by R. Stambaugh

AUG L. Horton or A. Kallenbach

DIII-D E. Strait

JT-60U N. Asakura

C-MOD A. Hubbard

MAST H. Meyer

NSTX R. Maingi


Joint meeting with Modelling group: presentations

R. Budny: simulation of heating &CD in ITER

A. Becoulet: latest ITER current profile simulation for ITER with

CRONOS

A. Fukuyama: latest ITER current profile simulation for ITER with TASK

M. Murakami: latest current profile simulation for ITER with ONETWO

Joint meeting with Modelling group: Nuclear Fusion paper

Steady state operation

K. Hanada: Impurity accumulation and expulsion in a TRIAM-1M long

pulse discharge

P. Politzer: Is a “steady-state" plasma necessarily stationary?


From JT-60U:Integrated performance <=> the ITER steady state domain

ITER_SS(I)E44104_8.3s

Prad

/Pheat

ne/n

GW

HHy2

N

fBS

fCD

fuel purity

1.32.56

0.5

1

0.770.56

0.83

Shall we add items:PedestalImpurity accumulationDivertor compabilityOthers?

Integration: meaning?



J T - 6 0 U

C u r r e n t p r o f i l e c o n t r o l

O b j e c t i v e o f c u r r e n t p r o f i l e c o n t r o l

o b t a i n b e t t e r c u r r e n t p r o f i l e f o r h i g h e r s t a b i l i t y & c o n f i n e m e n t

m a i n t a i n j ( r ) r o b u s t t o p e r t u r b a t i o n

J T - 6 0 U s t a r t e d j ( r ) c o n t r o l e x p . i n 2 0 0 4 .

C o n t r o l b y o f f - a x i s c o - C D , i n c o m b i n a t i o n w i t h o n - a x i s O H c u r r e n t

U s e o f c o - C D c o m p a t i b l e t o i n c r e a s i n g f C D

N o t s t r o n g l y s p e c i f i c t o c u r r e n t d r i v e r

B a s i c i d e a i s t o d e c r e a s e t h e l a r g e s t r e s i d u a l i n q , n o t t o d e c r e a s e a n a v e r a g e d r e s i d u a l .


J T - 6 0 U

q p r o f i l e c o n t r o l ( q ( 0 ) ~ 1 1 . 3 ) w a s d e m o n s t r a t e d .

w a s c o n t r o l l e d .

q ( r ) a p p r o a c h e d t o t h e r e f e r e n c e a t t = 1 3 s , a n d w a s s u s t a i n e d f o r 3 s .

n e = 0 . 5 x 1 0 1 9 m - 3

C D ~ 1 x 1 0 1 9 A / W / m - 2

R e f l e c t i o n r a t e ~ 5 %







20

Experiments in 2004 at ASDEX-U

AIMS:

• q-profile evolution in Hybrids, and MHD.

• Operation at 600kA/1.4T and 1.2MA/2.8T.

• Variation in q95 (and density) in collaboration with DIII-D.

• ICRH heating with PICRH > PNBI

21

Physics:• Scaling of the confinement with and * and stability (*,MHD).• Document the edge of the plasma.• Scaling to ITER.• Operation at high density, small ELMs ?

Scenario development:• Use of ICRH, towards on RF only demonstration.• Use of ECCD for q-profile and MHD control.

• Demonstrate at q95 ~3 or lower.

• Assess operation at low density with increased W surface.

Integration:• ELM control techniques with improved confinement.• International collaboration.

Still to be done on ASDEX-U.....


Joint experiment 2005 Steady-State Operation

current profile

q profile

high bootstrap (fBS70%) fraction

ITBs at large radius

Te/Ti effect on confinement

q and density

compare effects of tearing mode, fishbones,

and sawteeth

compare profile control techniques for SSO

JET, JT-60U, ASDEX-U, DIII-D

ASIPP ASIPP HT-7 HT-7

Experiments of full non-inductivecurrent drive on HT-7

X.D. Zhang, Z.W. Wu, Z.Y. Chen, X.Z. Gong, H. WangD. Xu, Y. Huang, J. Luo, X. Gao, L. Hu, J. Zhao

B.N. Wan, J. Li and HT-7 Team

Institute of Plasma Physics, Chinese Academy of Science

Hefei, 230031, CHINA

E-mail: [email protected]

20th IAEA Fusion Energy Conference, 1-6 November, 2004, Vilamoura, Portugal

ASIPP ASIPP HT-7 HT-7 AbstractAbstract

• Steady-state operation is a main goal, three types of experiment are used to study long pulse discharge, steady-state operation and full non-inductive current drive on HT-7.

• The results show that the plasma current in the full non-inductive current drive case is instable due to no compensation of OH heating field or self-induction loop voltage, this instability of plasma current will increase the interaction of plasma with limiter and first surface and bring impurity.

• All discharges of full non-inductive current drive are terminated because of impurity spurting.

• To adjust the LHW power for control the loop voltage during long pulse discharge is the most effective method for steady-state operation on HT-7.

ASIPP ASIPP HT-7 HT-7 Long pulse operations on HT-7Long pulse operations on HT-7

HT-7 Superconducting Tokamak R=1.22m a=0.27m BTmax=2.2T Ipmax =250KA ne=1.0~5.0x1019

m-3 Temax = 4 KeV Timax = 1.5 KeV

Bottom, top and high field side toroidal limiters

LHW systemMulti-junction grill type, 3 rows and 4x4 columns of waveguid

es,Nll=1.25~3.45, fLHW=2.45GHz, PLHWmax=1.2MW

Parameters for long pulse operationIP=50~60KA BT=1.8~2.0T neo=1.0x1019m-3 Te=0.5KeV

PLHW =100~400KW fLHW=2.45GHz Nll=2.35

ASIPP ASIPP HT-7 HT-7 Long pulse operations on HT-7Long pulse operations on HT-7

Three types of long pulse operation on HT-7 tokamak

The first type: long pulse dischargePlasma current droved by LHW + a fraction of OH current

The second type: steady-state operationPlasma current droved by LHW + to control VL~ 0

The third type: full non-inductive current drivePlasma current droved by LHW + without OH heating field

ASIPP ASIPP HT-7 HT-7 Type I: Long pulse dischargeType I: Long pulse discharge

Plasma current droved by LHW + a fraction of OH current

1. A little of loop voltage supplies fraction plasma current in high performance long pulse discharge.

2. Because of the limit of volt-second, the discharge will be terminated when the magnetic flux in iron core saturate.

3. In this case, the pulse length is limited, so which cannot be called as steady state operation.

4. The effect of OH heating field determines the operation state in long pulse discharge.

ASIPP ASIPP HT-7 HT-7 Type II: Steady state operationType II: Steady state operation

Plasma current droved by LHW + to control VL~ 0

• It is difficult to keep VL close to zero with constant PLHW.

• In a high-performance tokamak for steady-state operation, a turbulence of plasma or LHW system is not unavoidable.

• Steady-state operation need to adjust PLHW during discharge.

• A feedback control system of PLHW based on DEF signal (volt-second) is developed on HT-7, which will be used to reduce the compensation of OH heating field.

• The OH heating field only in a short time supplies some compensation, after the PLHW is adjusted and which can sustain the plasma current, the OH heating field will return to the initial value.


A degraded driving effect due to small density fluctuation can be compensated by OH heating field and increase PLHW.

Shot: 71349 shot: 71513


The adjust value cannot be large, to the larger turbulence which is also powerless and

the discharge will be terminated quickly.

Shot: 71349 shot: 71513

ASIPP ASIPP HT-7 HT-7 Type III: Full non-inductive current driveType III: Full non-inductive current drive

Plasma current droved by LHW + without OH heating field

“Genuine” non-inductive current drive

There are two phases in this case, normally the current droved by LHW is larger than the plasma current.

Phase I: negative VP, reverse compensating plasma current supplied by OH heating field to keep a constant IP.

Phase II: “genuine” non-inductive current drive, VP ~ 0, IOH ~ 0, saturated magnetic flux, no multi and self-induction.


• From phase I to II, the IP increase quickly in a short time (~4s) due to without multi and self-induction, or reverse compensating plasma current.

• The HX profile shows a off-axis deposition of LHW power in phase I and on-axis deposition in phase II on HT-7.


in “genuine” non-inductive current phase

without OH heating field and self-induction loop voltage

fluctuation of plasma parameters and LHW power

instability of plasma current and profile

interaction of plasma with limiter and first wall bring impurity or plasma density rise

unfavorable for current drive


The impurity signal of CV shows that the CV radiation layer is consistent with the deposition region of LHW power and the C impurity

will accumulate gradually in phase II on HT-7 (shot: 61576).

4s 18s7x10-3 1.7x10 -2

38s 51s2.2x10-2 2.8x10 -1


Non-inductive current drive without OH heating fieldconstant IOH without OH heating field

self-induction VL can retard the change of plasma current Actually which supplies a fraction of compensating current

shot: 72245 shot: 70208

ASIPP ASIPP HT-7 HT-7 ConclusionConclusion

• On HT-7 the LHW power can be adjusted by means of feedback control system according to the change of DEF signal (Volt-Second) during discharge.

• Because of a small adjusting value, that is powerless for a larger fluctuation. The fluctuations on HT-7 are only impurity and plasma density in steady-state operation.

• The experiments of constant IOH show that the self-induction loop voltage cans also stabilize a larger fluctuation and retard a sudden change of plasma current in short time.

• To adjust the LHW power for control the loop voltage during long pulse discharge is the most effective method for steady-state operation on HT-7.

ASIPP ASIPP HT-7 HT-7 DiscussionDiscussion

• The “genuine” non-inductive current drive is instable due to without multi and self-induction.

• A fraction of compensating current in short time for steady-state operation is needed, whether the compensating fraction is supplied by OH heating field, or self-induction loop voltage.

• The OH heating field should be allowed to supply some compensating plasma current and keep the stability of discharge when a small plasma fluctuation appears during discharge, which will return to the initial value after fluctuation.

• “Full non-inductive current drive” in full space of time and “inductive one” in local space of time.

• The final goal of steady-state operation is how to sustain a stable discharge with high performances in long time and which will be suitable for operation mode of ITER.

Documents

Introduction of 6 th Steady State Operation ITPA Topical Group Meeting X.D. ZHANG