hl-2a heating & current driving by lhw and ecw study on hl-2a bai xingyu, hl-2a heating team
TRANSCRIPT
SW IP HL-2AHL-2A
Heating & Current Driving by LHW and ECW study on HL-2A
Bai Xingyu, HL-2A heating team
SW IP HL-2AHL-2AOutline
Introduction
EC experiments
ECCD experiments
ECRH experiments
Pre-ionization and Assisted Startup
LHCD experiments
LHCD &ECCD experiments
Summary
SW IP HL-2AHL-2AIntroduction
HL-2A is a normal
Tokamak device o
f China, located in
SWIP Chengdu Si
chuan Province. It
s main parameters:
Bt=2.7T, t=5s, R=1.65m, r=0.4m, Te=5keV, Ip=450kA,ne=6*1019m-3
HL-2M is on building
SW IP HL-2AHL-2AIntroduction
EC system:
68GHz :6*500kW gyrotrons2 antenna in 2 windowsRotatable mirror Duration 1s*4+1.5s*2
140GHz :2*1MW gyrotrons1 shared antennaRotatable mirrorDuration 3s
8 gyrotrons for ECRH
SW IP HL-2AHL-2AIntroduction
LH system:2*500kW klystrons2*12 antennan||=2.75
f=2.45GHz
SW IP HL-2AHL-2AOutline
Introduction
EC experiments
ECCD experiments
ECRH experiments
Pre-ionization and Assisted Startup
LHCD experiments
LHCD &ECCD experiments
Summary
SW IP HL-2AHL-2AEC experiments
EC antenna structure of HL-2A
EC antenna (new):
Rotatable in P direction:Lower 2 mirrors1MW/140GHz only
Rotatable in T direction:All mirrorsLeft for right & right for le
ft
SW IP HL-2AHL-2A
In ECRH condition, Ip=IOH+Ib+IEC
Where IOH=Vl / R
Vl is loop voltage
R is the plasma resistance
Ib≈cɛ1/2p Ip is Bootstrap current
c≈1/3 is proportionality constant
ɛ is the aspect radio
IEC is driving current
ECCD experiments
For the plasma is approximate constant,
R& p is constant
We know that IEC0=0 when EC is inject
ed in vertical direction
So the driving current in different direc
tion can be obtained by
IEC≈(1-cɛ1/2p)(Ip-Vl Ip0/Vl 0)
Where Ip0&Vl 0 are separately plasma c
urrent and loop voltage in vertical i
njection condition
SW IP HL-2AHL-2AECCD experiments Shot Φ
(degree)dIOH/dt (kA/
s)IEC(kA) EC(1019A
m-2W-1)
20104 -8 -10.534 -11.91 0.098
20105 -6 -11.402 -25.66 0.122
20106 -4 -10.149 -5.813 0.033
20107 0 -9.782 0 0
20108 -10 -10.51 -11.53 0.08
ECCD efficiency
has an optimized
inject angle
SW IP HL-2AHL-2AECRH experiments
H mode is obtained for the first time on H
L-2A in 2009 ( shot 11333)H mode can be obtained by ECRH and N
BI or only NBI on HL-2APEC=1.62MW, PNBI=0.26MW (22151)
NBI power is much less than the H mode threshold
(MIN NBI power is 570kW for L-H transition)
The output power of EC system (3MW/68GHz) can r
each 2.5MW
Can H mode be obtained only by ECRH ?
ECRHNBI
SW IP HL-2AHL-2AECRH experiments
ECRH-H modeW7-AS[V. Erckmann, PRL1993]0.45MW/140GHz/X2
DIII-D[J. Lohr, PRL1988]60GHz/0.9MW/X2 r/a - 0~0.3
ASDEX-U[F. Ryter, NF2009]140GHz/>1.3MW/X2 r/a=0~0.3
SW IP HL-2AHL-2AECRH experiments SMBI makes ne increase rapidly. limit cycle oscillation
(LCO) appears in the following ne-decrease section
Conditions:
• Siliconized wall
• Ne is controlled above 1.5 by SMBI
• Displacement and X point angle control
• Bt=1.34, inject point r/a=0.45
• ECRH power1.5MW
Long SMBI
SW IP HL-2AHL-2AECRH experiments
LCO phenomenon with ELMs feature 22909 NBI H-mode
23065
1kHz
Bt~1.31T, r/a~0.3, PECRH ~1.6MW
During ECRH, the displacement is c
ontrolled minus to avoid cutting off. Ne i
s feedback controlled 1.75 by SMBI.
LCO frequency is 2-3kHz. Once (700ms
~800ms) 1kHz component appears. And t
he oscillation waveform has ELMs featur
e
SW IP HL-2AHL-2AECRH experiments
Pump out phenomenon:
Ne decreases while ECRH
power increases and remain
stable at a certain value. In
the new profile, ne
decreases in core and
increases on the edge. Ne
profile is changed from
peaking to hollow
NBIECRH
In the ECRH H mode
experiments, pump out
phenomenon is a big
problem
ECRH Te↑
ne ↓
Power threshold ↑
electron-ion collision rate↓
Ti ↓
Harder L-H transition
SW IP HL-2AHL-2APre-ionization & Assisted Startup
On HL-2A, in order to build up scenarios for ECRH pre-ionization and assisted startup
to relax the conditions required to breakdown and startup plasma on HL-2M, and
to clarify the ITPA IOS2.3 open issue, ECRH pre-ionization and assisted startup experim
ents have been carried out during 2010, 2011 and 2012 experiment campaigns
SW IP HL-2AHL-2APre-ionization & Assisted Startup
Waveform for min ECRH power and pure ohmic start up
Min breakdown voltage : 0.5V Toroidal Electric field : 0.05V/m ( 1/6 ITER value)Tt is the smallest value ever obtained by TokamakMin breakdown voltage of ohmic: 3.4VThe minimum breakdown voltage was reduced much
SW IP HL-2AHL-2AITPA IOS2.3 open issue
The earlier application of loop voltage does not delay or hinder the av
alanche formation on HL-2A, and even better than that of later appli
cation of loop voltage. There is no problem for earlier application of l
oop voltage.
Why shorter delay times for earlier application? Loop voltage may accelerate t
he initial free electrons (about 0.03 eV) to a higher energy value close to subcri
tical energy, so the X2 mode absorption rate become higher, which causes the e
arlier breakdown.
SW IP HL-2AHL-2APre-ionization & Assisted Startup
Shot: 14444O1-modeP=200kWt=108ms, 117ms
Shot: 16289X2-modeP=600kWt=108ms, 117msangle 0°,
Shot: 16617X2-modeP=800kWt=126ms, 135msangle 20°
The minimum ECRH powers
O1- mode: 200kW
X2- mode: 300kW
Parameter influence
wall condition
prefilled gas pressure
field null structure
toroidal injection angle
SW IP HL-2AHL-2AOutline
Introduction
EC experiments
ECCD experiments
ECRH experiments
Pre-ionization and Assisted Startup
LHCD experiments
LHCD &ECCD experiments
Summary
SW IP HL-2AHL-2A
In LHCD condition, Ip=IOH+Ib+ILH
Where IOH=Vl / R
While without LHCD, Ip0=IOH0+ Ib0
For the plasma current is feed back controlled, Ip should be the same as that
without LHCD. Ib is considered to be constant and small (less than 10% Ip )
Ip = Ip0, Ib = Ib0 , Ip ≈ IOH=Vl / R,
So, ILH=IOH0-IOH
Which means
ILH ≈ Ip ΔVl /Vl
But the fact is a little more complex. Ip is not controlled completely.
LHCD experiments
SW IP HL-2AHL-2ALHCD experiments
ILH is formed by 2 components:
ILH =IΔVl + ΔIp
Where ΔIp can be read from data
Typical LHCD result on HL-2A
SW IP HL-2AHL-2ALHCD experiments
ShotLHCD power( kW)
LH
(1019Am-2W-1)
RC(%)
limiter( cm)
Ne
(1019m-3)
9751 57.5 0.085 30.6 39 1.1
9752 57 0.094 28.9 39 1.8
9763 89.8 0.013 15.5 38 0.9
9771 95.8 0.059 36.4 38 0.86
9772 95.1 0.062 35.8 38 0.92
9773 101.2 0.033 37 38 1.85
9778 123.1 0.032 23.2 38 0.84
9782 119.2 0.077 26.8 38 0.57
9788 92.5 0.155 29.8 38 1.45
9789 92.2 0.254 36.3 38 0.91
9790 95.1 0.171 36.3 38 0.82
9791 93.5 0.181 35.7 38 0.95
9964 48.4 0.01 20.3 38 0.56
9965 39.3 0.05 35.1 38 0.6
LHCD efficiency on HL-2A
SW IP HL-2AHL-2AOutline
Introduction
EC experiments
ECCD experiments
ECRH experiments
Pre-ionization and Assisted Startup
LHCD experiments
LHCD &ECCD experiments
Summary
SW IP HL-2AHL-2ALHCD &ECCD experiments
Full CD obtained by LHCD&ECCD
shot RC(%) With ECCD
9771 36.4 NO
9772 35.8 NO
9773 37 NO
9774 34.2 YES
9775 28.2 YES
9776 25.1 YES
9777 22.3 YES
9778 23.2 YES
9779 Ip disturb YES
9780 Ip disturb YES
9781 26.2 YES
9782 26.8 YES
ECCD improve absorption of LHW
Why ECCD can improve LHW absorption?Pump out phenomenon makes particle move out,
which increase edge density. That form a puffi
ng gas effect on the edge, which make LHW co
upling better.
SW IP HL-2AHL-2AOutline
Introduction
EC experiments
ECCD experiments
ECRH experiments
Pre-ionization and Assisted Startup
LHCD experiments
LHCD &ECCD experiments
Summary
SW IP HL-2AHL-2ASummary
EC experiments was carried out on HL-2AECCD efficiency was estimated and compared with theory
H mode experiments by ECRH only was tried. LCO phenomenon with ELMs f
eature was obtained
Pre-ionization and assisted startup experiment by ECW was carried out. The s
mallest Toroidal electric field ever in Tokamak is obtained. The result shows that
earlier application of loop voltage does not delay or hinder the avalanche formati
on, even better, which solves ITPA IOS2.3 open issue
LHCD experiments was carried out on HL-2ALHCD efficiency was estimated
LHCD &ECCD experiments was carried out alsoFull CD was observed
ECCD improve LHCD coupling phenomenon was achieved and analyzed
SW IP HL-2AHL-2A