RF simulation at ASIPP

Bojiang DING

Institute of Plasma Physics, Chinese Academy of Sciences

Workshop on ITER Simulation, Beijing, May 15-19, 2006

ASIPP

OUTLINE

• LHW

• ICRF

• Synergy of LHW and ICRF/IBW

• Future Considerations

• Summary

ASIPP

• LHW

Coupling between LHW and Plasma

Ray tracing and current drive

Effect of LHCD on radial electric field

ASIPP

Coupling between LHW and Plasma

The launched spectrum from the LHW antenna can be calculated at a given plasma condition.

Effects of wave-guide phase difference and plasma condition on the power spectrum and the reflection

are obtained.

1.0 1.5 2.0 2.5 3.0 3.5 4.0-10

0

10

20

30

40

50

60

70

Po

we

r D

en

sity(a

.u.)

N//

=-90O

=-60O

=-30O

=0O

=30O

=60O

=90O

=120O

=150O

=180O

LHW Spectra at different LHW Spectra at different

Ray tracing and current drive

With combining a ray-tracing code and a 2-D Fokker-Planck equation, we can calculate ray-trace of wave beam, power deposition, driven plasma current profile.

The radial diffusion of fast electron is considered.

It is only valid for the circular cross section plasma.

It can be used to explain HT-7 experimental results effectively.

Ray trace of the wave beam （ N//

peak=2.95)

-1.0 -0.5 0.0 0.5 1.0-1.0

-0.5

0.0

0.5

1.0

r / a

r / a 0 5 10 15 20 25 30

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4Ne=1.5Te(0)=800eV)B

t=2.0T

N//

minor radiu (cm)

Power deposition and driven current vs

0 5 10 15 20 25 30

0.0

5.0x103

1.0x104

1.5x104

2.0x104

2.5x104

3.0x104

3.5x104

4.0x104

4.5x104

Bt=2.0TNe=1.5Te(0)=800eVIp=120kA

Prf=300kW

=1500

=1300

=1100

=900

Po

wer

dep

osi

tio

n d

ensi

ty (

a.u

.)

Minor radiu (cm)

0 5 10 15 20 25 300

200

400

600

800

1000

1200

1400

Bt=2.0Ne=1.5Te(0)=800eVIp=120kA

Prf=300kW

=1500, I

rf=94kA

=1300, I

rf=117kA

=1100, I

rf=80kA

=900, I

rf=65kA

Cu

rren

t d

ensi

ty (

Acm

-2)

Minor radiu (cm)

Power deposition and driven current vs BBtt

0 5 10 15 20 25 300.0

5.0x103

1.0x104

1.5x104

2.0x104

2.5x104

3.0x104

3.5x104

4.0x104

4.5x104

=1300

Ne=1.5Te(0)=800eVIp=120kA

Prf=300kW

Bt=1.7T Bt=2.0T

Pow

er d

epos

ition

den

sity

(a.u

)

Minor radiu (cm)

0 5 10 15 20 25 300

200

400

600

800

1000

1200

1400

=1300

Ne=1.5Te(0)=800eVIp=120kAP

rf=300kW

Bt=2.0T, I

rf=117kA

Bt=1.7T, I

rf=102kA

Cu

rren

t d

ensi

ty (

Acm

-2)

Minor radiu (cm)

Power deposition and driven current vs TTee

0 5 10 15 20 25 300

1x104

2x104

3x104

4x104

=1300

Bt=2.0TNe=1.5Ip=120ka

Prf=300kW

Te(0)=800eV Te(0)=1.2Kev

Pow

er d

epos

ition

den

sity

(a.u

.)

Minor radiu (cm)

0 5 10 15 20 25 300

200

400

600

800

1000

1200

1400

1600

1800

=1300

Bt=2.0TNe=1.5Ip=120ka

Prf=300kW

Te(0)=800eV, Irf=117kA

Te(0)=1.2keV, Irf=134kA

Cur

rent

den

sity

(Acm

-2)

Minor radiu (cm)

A typical waveform of LHCD experiments (#46693) ne=1.51019m-3 , Ip=220kA, BT=2.0T, , N//

peak=2.9 ,PLH =240kW.

050

100150200250

0.0

0.5

1.0

1.5

2.0

-0.50.00.51.01.52.02.53.0

-0.5

0.0

0.5

1.0

0.0 0.3 0.6 0.9 1.20

50100150200250300

0.0 0.3 0.6 0.9 1.2-0.50.00.51.01.52.0

Phase II(LHCD Phase)

Phase I(OH Phase)

Phase I(OH Phase)

Phase II(LHCD Phase)

I p(k

A)

ne(

101

9 m-3)

Vp(V

)

Inte

nsit

y o

f

so

ft x

-ray (

a.u

.)

LH

W p

ow

er

(kW

)

Time (s)

D(

a.u

.)

Time (s)

ASIPP

An ITB seems visible in the region around r/a ~ 0.55An ITB seems visible in the region around r/a ~ 0.55

Electron temperature profiles Ion temperature profiles

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0

0.2

0.4

0.6

0.8

1.0

1.2 ITB

OH phase LHCD phase

Ion

tem

pera

ture

(keV

)r / a

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2 ITB

OH phase LHCD phase

Ele

ctro

n t

emp

erat

ure

(ke

V)

r / a

ASIPP

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0

0.1

0.2

0.3

0.4

De

po

sit

ed

po

we

r d

en

sit

y (

Wc

m-3)

r / a

0.0 0.2 0.4 0.6 0.8 1.00

100

200

300

400

500

600

700

before LHCD (OH phase) after LHCD (LHCD phase)

Cur

rent

den

sity

(Acm

-2)

r / a

Power deposition and current density profile

ASIPP

0.0 0.2 0.4 0.6 0.8 1.00.0

0.5

1.0

1.5

2.0

2.5

3.0

q

r / a

after LHCD (LHCD phase) before LHCD (OH phase)

a low magnetic shear is possibly formed because of the hollow current profile inside the surface of q=2

(r/a~0.8). Experiments described in

early references show that a low magnetic shear inside the

q=2 surface is a favorable condition to form an ITB

ASIPP

Effect of LHCD on radial electric field

Based on electron’s radial force equilibrium and the LHCD simulation code, the effect of LHCD on radial electric field profile is calculated.

It possibly offers a tool for explaining LHCD to improve plasma confinement.

0.0 0.3 0.6 0.9 1.2 1.5 1.80.0

0.20

50

1000.3

0.60

1

0

1

0100200300

0100200300

0

1

0

1

0.3

0.6

(f)

D

(a.u

.)

Time (s)

(e)

S-x

-ra

y (a

.u.)

Te(0

)

(ke

V)

H-x

-ra

y (a

.u.)

PL

HW

(kW

)

I. R

. (a

.u.)

I. G

.(a

.u.)

(d)

(c)

n e

(101

9 m-3)

(b)

Vp

(V)

I p

(kA

) (a)

Typical waveforms of LHCD experiment with eITB

0 5 10 15 200.2

0.4

0.6

0.8

1.0

1.2

1.4T

e (k

eV)

Minor radius (cm)

OH (315ms) LHCD (525ms) LHCD(945ms) LHCD(1365ms)

Electron temperature profiles in OH and LHCD phase

Magnetic shear decreases during the LHCD plasma

Simulation results with the experimental parameters (a) power deposition profile (b)driven current profile and q profile

0 5 10 15 20 25 300

100

200

3000.0

0.5

1.0

1.5

2.0

2.5

0

1

2

3

4(b)

q(r) (OH) q(r) (LHCD)

j(r) (

Acm

-2)

Minor radius (cm)

j(r) (OH) j(r) (LHCD)

q(r)

Pow

er d

ensi

ty (W

cm-3

)

(a)

A notch structure in Er is formed near the layer with strong deposition

of LHW.

The largest Er (LHCD) gradient locates at the position of ~10cm, which i

s well consistent with the ITB region indicated by the Te profile.

Simulated profiles of (a) radial electric field and (b) its shear in OH and LHCD phase

0 5 10 15 20 25 30-2000

-1000

0

1000

2000-120

-80

-40

0

(b)

dE

r/d

r (k

Vm

-2)

Minor radius (cm)

OH LHCD

Er(

kVm

-1)

Er(OH)

Er(LHCD)

Er

(a)

• ICRF

Coupling between ICW and Plasma

Ray-tracing code for IC waves in tokamak plasma

ASIPP

Coupling between ICW and Plasma(ANT10 from Japan)

The coupling of the antenna is calculated in a slab geometry.

The model is three dimensional and includes the effect of connections to a transmission line.

The coupling code based on the variational principle can give the self-consistent current flowing in the antenna, the field excited inside the plasma, and the antenna impedance for circular shape plasma.

Impedance versus the distance

Ey distribution at the plasma surface (0,)

Ray-tracing code for IC waves in tokamak plasma

Ray trace of wave beam, power deposition profile in plasma are obtained.

ICRF wave propagation and deposition for a noncircular tokamak can also be studied.

Plasma temperature can be modified by the ICRF heating.

-0.4 -0.2 0.0 0.2 0.4-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

Y (m

)

X (m)

ray 1

Poloidal

=0.4,=1.8,f=55MHz,Bt =3.5T, Te(0)=2.0keV, Ti(0)=3.0keV,nH / nD =0.15,ne(0)=3.5x10 19 m –3 , nea=9.0x10 18 m –3

-3 -2 -1 0 1 2 3-3

-2

-1

0

1

2

3

Z(m

)

X (m)

ray 1

Toroidal

Ray tracing for EAST D(H) scenario

0.0 0.1 0.2 0.3 0.41E-4

1E-3

0.01

0.1

1

e H D

po

we

r d

ep

ositio

n p

rofile

(w

/A2)

(m)

e H D

Ti=1.4kevTe=1.6kev

Ti=3.0kevTe=1.5kev

Power deposition profiles for EAST D(H) scenarios at different temperatures

=0.4,=1.8,f=55MHz,Bt =3.5T,nH /nD =0.15,ne(0)=5x10 19 m–3 , nea=5x10 18 m–3

Synergy of LHW and ICRF/IBW

Synergy of LHW and IBW (From FTU, Italy)

Synergy of LHW and ICRF

Synergetic effects of LHW and IBW/ICRF are preliminarily simulated for HT-7 tokamak.

The electron distribution, LHW power deposition and driven current are affected by both IBW and fast wave.

The work is just a kick-off, further work is under process.

Electron distribution function with (a) LHW (b) LHW+IBW

LHW power deposition

0 3 6 9 12 15 18 21 24 27

0.0

8.0x103

1.6x104

2.4x104

3.2x104

4.0x104

Po

we

r D

ep

osi

tion

(W)

minor radius(cm)

LHWLHW+IBW(n

//=6)

LHW+IBW(n//=8)

LHW+IBW(n//=10)

LHW+IBW(n//=12)

0 3 6 9 12 15 18 21 24 270

200

400

600

800

1000

dri

ven

cu

rre

nt d

en

sity

(A/c

m2)

minor radius(cm)

LHWLHW+IBW(n

//=6)

LHW+IBW(n//=8)

LHW+IBW(n//=10)

LHW+IBW(n//=12)

Driven current profile

Profiles of LHW power deposition and driven current without fast wave

Profiles of LHW power deposition and driven current with fast wave

0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30

0

20

40

60

80

100

120

minor radius(m)

Po

we

r a

bso

rptio

n(W

)

0

10

20

30

40

50

60

Cu

rre

nt d

rive

n(A

)

0.00 0.05 0.10 0.15 0.20 0.25 0.30

0.0

5.0x105

1.0x106

1.5x106

2.0x106

2.5x106

minor radius(m)P

ow

er

ab

sorp

tion

(W)

-2.0x105

0.0

2.0x105

4.0x105

6.0x105

8.0x105

1.0x106

1.2x106

1.4x106

Cu

rre

nt d

rive

n(A

)

Future ConsiderationWe intend to develop the simulation of coupling, propagation, heating, current dr

ive for LHW and IBW/ICW, and the synergy of LHW and IBW/ICW for EAST tokamak, even for ITER. After that, we intend to couple the plasma transport to the above code with the co-operation of other divisions and laboratories.

1. The coupling of wave and plasma in the non-circular cross section

2. The propagation and absorption of LHW in the non-circular cross section

3. Full wave code for IC waves in tokamak for circular / noncircular plasmas (Toric, from Germany)

4. Synergetic simulation of LHW and IBW/ICRF

5. Combination of Transport and heating/drive simulation

.

.

.

SummaryThe coupling between wave and plasma in the slab geometry is

obtained, the more complicated geometries are under process.

The ray tracing and current drive of LHW in circular plasma are achieved, the extension to the non-circular case is possible.

The present ICRF code is based on the ray-tracing method, the full wave code (TORIC) is under development.

Synergetic simulation of LHW and IBW/ICRF is underway.

Combination of Transport and heating/drive simulation will be done next.

Thank you for your attention!