ECH/ECCD Experiment in Heliotron J - POSTECHpsl.postech.ac.kr/jws05/talks/...ECH_ECCD_experiment_in_Heliotron_J.pdf · ECH/ECCD Experiment in Heliotron J Presented by K. Nagasaki

ECH/ECCD Experiment in Heliotron J

Presented by K. Nagasaki

Institute of Advanced Energy, Kyoto University Graduate School of Energy Science, Kyoto University

Faculty of Engineering, Hiroshima UniversityNational Institute for Fusion Science

CIEMAT

Japan-Korea Workshop, October 24, 2005, POSTECH, Korea

F. Sano 1) , T. Mizuuchi 1) , K. Kondo 2) , K. Nagasaki 1) , H. Okada 1) , S. Kobayashi 1) , K. Hanatani 1) , Y. Nakamura 2) , S. Yamamoto 1) , Y. Torii 1) , Y. Suzuki 2), H. Shidara 2), H. Kawazome 2) , M. Kaneko 2) , H. Arimoto 2) , T. Azuma 2) , J. Arakawa 2) , K. Ohashi 2) , M. Kikutake 2) , N. Shimazaki 2) , T. Hamagami 2) , G. Motojima 2) , H. Yamazaki 2) , M. Yamada 2) , H. Kitagawa 2) , T. Tsuji 2) , H. Nakamura 2) , S. Watanabe 2) , S. Murakami 3) , N. Nishino 4) , M.Yokoyama 5) , Y. Ijiri 1) , T. Senju 1) , K. Yaguchi 1) , K. Sakamoto 1) , K. Tohshi 1) , M. Shibano 1) , V. Tribaldos 6) , V.V.Chechkin 7)

Contributors

1) Institute of Advanced Energy, Kyoto University, Gokashou, Uji, Japan2) Graduate School of Energy Science, Kyoto University, Kyoto, Japan 3) Graduate School of Engineering, Kyoto University, Kyoto, Japan 4) Graduate School of Engineering, Hiroshima University, Hiroshima, Japan5) National Institute for Fusion Science, Toki, Gifu, Japan6) Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, Spain7) Institute of Plasma Physics, NSC KIPT, 61108 Kharkov, Ukraine

Contents

• Heliotron J Device

• H-mode transition

• Electron Cyclotron Current Drive

• Electron Bernstein wave heating

Planned/Operating Spatial-Axis Helical Systems

Plasma Device(Laboratory)

H-1NF(ANU)

TJ-II(CIEMAT)

HSX(U. Wisconsin)

Heliotron J(Kyoto Univ.)

W7-X(MPI)

NCSX(PPPL)

Schedule 1993~ 1997~ 1999~ 1999~ 2005~ ?

Coil SystemM=3

HFC+CR+TFCM=4

HFC+CR+TFCM=4

Modular CoilM=4

HFC+TFCM=5 SC

Modular CoilM=4

?Major RadiusMinor Radius

Plasma VolumeMagnetic FieldPulse Length

1.0 m0.22 m0.96 m3

1.0 T1 sec

1.5 m0.1-0.25 m

1.43 m3

1.5 T0.5 sec

1.2 m0.15 m0.44 m3

1.37 T0.2 sec

1.2 m0.18 m0.82 m3

1.5 T0.5 sec

6.5 m0.65 m54 m3

3.0 T> 10 sec

1.5m0.42m

?1.2T

0.5sec

Heating SystemECH (0.2MW)

Helicon(~ 0.5MW )

ECH (0.6MW)NBI (4MW)

ECH (0.2MW)ECH (0.5MW)NBI (1.5MW)ICH (2.5MW)

ECH, ICHNBI

(20-30MW)

ECH (0.1MW)NBI (7MW)

FeaturesFlexible

configuration,High beta

High rotational transform,Low shear

Quasi-helical symmetry

Local quasi-isodynamicity

Quasi-isodynamicity

Quasi-omnigeneity

Schematic View

Heliotron J Device

Toroidal Coil AVertical Coil Toroidal Coil B

Vacuum Chamber

Device Parameters of Heliotron J

Coil SystemL=1/M=4 helical coil 0.96MATToroidal coil A 0.6MATToroidal coil B 0.218MATMain vertical coil 0.84MATInner vertical coil 0.48MAT

Major radius 1.2mMinor radius of helical coil 0.28mVacuum chamber 2.1m3

Aspect ratio 7Port 65Magnetic Field 1.5TPulse length 0.5secPitch modulation of helical coil

Inner Vertical Coil

Toroidal Coil A

Outer Vertical Coil

Toroidal Coil BHelical Coil

Plasma

Vacuum Chamber

sin( )

0.4

M ML L

θ π φ α φ

α

= + −

= −

Heating and Diagnostic System

70 GHz ECH

Steering Mirror

(Horizontal Port)

Equivalent current direction by Bθ

Pump/QMA/CAMERABT (CW)

ECE

Thomson

Probe

PHA/VUV

VUV/NPA

Ti Gettering

SX(Foil)

CAMERA

NBI

Fixed Probe

70 GHz ECH(Vertical Port)

Rogowski Coils

MP

DiamagneticLoops

SX Arrays

2.45GHz ECH

VisibleSpec.

Hα Gas Inlet

ECHBolometer

Microwave Interferometer

NBI

Magnetic Configuration

Corner section (φ=45 deg)Straight section (φ=0 deg)

ωce/ω=0.5ωce/ω=1.0

70GHz ECH/ECCD System for Heliotron J

Gyrotron

MOUPolarizer

Miter bend

Power Monitor

Corrugated waveguide for HE11 mode (<10-3 Torr)

Barrier window

Last Closed Flux Surface Steering

Plane mirror

Corrugated Waveguide for HE11 mode

Boron Nitride Barrier Window

Focusing Mirror

Injection Power 400kW max (one gyrotron)Pulse duration 0.2sec maxInjection mode Focused Gaussian beam

ECH Launcher• The spot size is much smaller than the plasma minor radius

at the perpendicular injection (22 mm << 170 mm).

0 500 1000 1500 20000

10

20

30

40

50

60

70

1/e2 p

ower

radi

us [m

m]

Distance from wavegaide exit [mm]

quasi-optical theory experiments

Barrier Window

Magneticaxis

Steering Plane Mirror

Focusing Mirror

-120 -90 -60 -30 0 30 60 90 1200.00

0.05

0.10

0.15

0.20

0.25Distribution in vertical direcion (+390mm)

Inte

nsity

[a.u

.]

Distance from center [mm]

1/e2 power radius: 44mm

0

0.1

0.1

0.2

0.3

0.3

0.4

0.4

0.5

Contents

• Heliotron J Device

• H-mode transition

• Electron Cyclotron current drive

• Electron Bernstein wave heating

H-mode Transition in ECH Plasmas

• The maximum increment in ∆Wpdiam/Wpdiam reaches 100%.

• This H-mode is transient in the time scale of τE

exp, but the HISS95-factor reaches ~1.8 during Phase II.

• This H-mode is terminated by a radiation collapse which is caused by the ECH-cutoff at densities ne > 2×1019m-3.

Radial Profiles of Edge Plasma Parameters at Transition Phase

-20 0 20 40 60 800.00

0.05

0.10

0.15

0.20

before after

I s(A

)

-20 0 20 40 60 80-5

0

5

10

15

20

25

Vf1(V

)-20 0 20 40 60 80

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

I~/I

∆R (mm)

-20 0 20 40 60 800

5

10

15

20

Γ~

⊥ (a.

u.)

∆R (mm)

ι(a)/2π=0.538 ECH+NBI #15369-#15377

増加

減少

ι(a)/2π=0.538

Iota dependence of peak HISS95-factor

τEexp = Wp

diam/PLOSS

PLOSS = Pabs - ∂Wpdiam/∂t

Pabs=ηabs(ECH) ·PECH + ηabs(NBI) ·PNBI

τEISS95=0.08 a2.2 R0.65 ne

0.51 PLOSS-0.59 B0.83 ι0.4

HISS95= τE

exp/τEISS95

The high-quality H-mode (1.3<HISS95<1.8) is achieved in the iota range slightly less than but not on the major natural resonances of n/m=4/8, 4/7 and 12/22.

Contents

• Heliotron J Device

• H-mode transition

• Electron cyclotron current drive

• Electron Bernstein wave heating

Toroidal current can be suppressed by ECCD

• Oblique ECH drives a toroidal current.

• The ECCD current is the same order of the bootstrap current, andcompensates the bootstrap current by controlling the injection angle.

-5 0 5 10 15 20 25Toroidal Injection Angle (degree)

-2.0

-1.5

-1.0

-0.5

0.0

I p (k

A)

Rev. B (CCW)

High Density

-5 0 5 10 15 20 25 30Toroidal Injection Angle (degree)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Toro

idal

Cur

rent

(kA

)

-5 0 5 10 15 20 25 30Toroidal Injection Angle (degree)

-0.6

-0.4

-0.2

0.0

0.2

0.4

I p (k

A)

-5 0 5 10 15 20 25 30Toroidal Injection Angle (degree)

-0.6

-0.4

-0.2

0.0

0.2

0.4

I p (k

A)

Rev. B (CCW)

Low Density

Density Dependence of EC Current

• 70GHz 2nd harmonic ECCD（300kW, 100msec) • Weak dependence on electron density

-20 -10 0 10 20 30Toroidal Angle (degree)

0.0

0.5

1.0

1.5

2.0

I p (k

A)

ECCD Experiment ( #10048-#10070 ) ( #8306-#8750 )

ne∼1x1019m-3ne<0.5x1019m-3

Comparison with Linear Theory

• The EC current experimentally measured is a few kA, and is weakly dependent on the electron density.

• This current is much less than the calculation results obtained by a ray tracing code based on a linear theory.

• Effect of weak single pass absorption or trapped electrons？

-5 0 5 10 15 20 25 30Toroidal Injection Angle (degree)

-0.6

-0.4

-0.2

0.0

0.2

0.4

I p (k

A)

B (CW)

-30 -20 -10 0 10 20 30 40-40

-30

-20

-10

0

10

20

30

40

0

20

40

60

80

100

Ip (kA)

I ECCD (kA

)

Toroidal Injection Angle (deg)

Pabs(%)

Contents

• Heliotron J Device

• H-mode transition

• Electron cyclotron current drive

• Electron Bernstein wave heating

Electron Bernstein Wave Heating

• Electromagnetic wave heating is not so efficient at high density in electron cyclotron heating (ECH).

– The appearance of cut-off layer– The power deposition becomes wide due to the strong

refraction.• In spherical tori, the conventional ECH is not applicable,

because the plasma is dielectric, ωpe>ωce.• The use of electron Bernstein waves (EBW) are a heating

method for high density plasmas.No cut-off densityVery high single pass power absorption even at low

temperatureThe mode conversion is required to excite the EBW.

High Density ECH Plasmas in Heliotron J

• Frequency: 53.2GHz• Injection Power:400kW max• Injection Mode: TE02• Three injection ports (outside of the torus)

Tangential view of ECH plasma160 180 200 220 240 2600.0

0.5

1.0

1.5

2.00.0

0.1

0.2

0.3

0.4

0.50

1

2

3

40.0

0.2

0.4

0.6

0.8

1.00.0

1.0

2.0

3.0

ne (1019m-3)

Hα (a.u.)

ECE 75GHz (a.u.)

OV (a.u.)

53GHz ECH (a.u.)

53GHz ECH #05516

Time (msec)

Non-Electromagnetic Resonant Heating in Heliotron J

• The efficient core heating has been observed at w0/w~0.7.

• There is no resonance for electromagnetic waves at the core region.

• The fundamental resonance is located at r/a>0.8.

0.6 0.8 1.0 1.2 1.40.0

0.2

0.4

0.6

0.8

1.00.4 0.5 0.6 0.7

Wp

(kJ)

B(0)φ*=0 (T)

000728-000929#1595-2505 2nd Harmonic

Resonance

ω0/ω

ωce/ω=0.5

ωce/ω=1.0

Slow X-B Heating in Heliotron J

• The waves can enter into the plasma as the X-mode through the edge window.

• Once the X-mode propagates in the plasma, it reaches the UHR layer, then is converted into the B-mode.

• The B-mode is fully absorbed in the plasma without escaping.

• Position of UHR layerr/a=0.0 at ne=1.4x1019m-3

r/a=0.5 at ne=1.9x1019m-3

r/a=1.0 at ne=2.2x1019m-3

UHR

ωc

• Experimental results related to ECH physics has been presented.

• The L-H transition has been observed in ECH, NBI and ECH+NBI plasmas.

– The high-quality H-mode (1.3<HISS95<1.8) is achieved in the specific iota range slightly less than the major natural resonances.

– The fluctuation-induced transport is reduced in the SOL region.

• Electron cyclotron current drive has been studied.– The EC current flows in the direction that the linear theory predicts.

– The EC current is comparable to the bootstrap current.

– The total current can be zero by controlling the EC injection angle.

• Electron Bernstein wave heating is possibly observed.– Effective core plasma heating has been observed in Heliotron J without

electromagnetic resonances in the core region.

– The slow X-B mode conversion process is a possible heating mechanism.

Summary