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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!
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