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SUNIST- Sino UNIted Spherical Tokamak
Preliminary experiment of plasma current startup by ECR wave on SUNIST spherical tokamak
HE Yexi, ZHANG Liang, *FENG Chunhua, FU Hongjun, GAO Zhe, TAN Yi, WANG Wenhao, *WANG Long, *YANG Xuanzong, XIE Lifeng
[email protected], 86-10-62791874 (o), 86-10-62782658 (fax)
SUNIST United LaboratoryDepartment of Engineering Physics, Tsinghua University, Beijing 100084, P.R.China
*Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China
JSPS-CAS Core University Program, 2005
This work was supported by JSPS-CAS Core-University Program on Plasma and Nuclear Fusion, the National Nature and Science Fund of China (Grant numbers: 10275041 and 10375089) , and International Atomic Energy Agency (Research contract No. 12935/R0) .
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SUNIST spherical tokamak
Preliminary result
Remained questions
SUNIST United Laboratory
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SUNIST United Laboratory
founded in 2004, consists of Department of Engineering Physics, Tsinghus Unive
rsity (DEP) ; Institute of Physics, Chinese Academy of Science (IOP) and keeping
very close collaboration with Southwestern Institute of Physics (SWIP) and Instit
ute of Plasma Physics, Chinese Academy of Science (IPPAS).
Members of SUNIST LaboratoryHe, Yexi Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R.China, 86-10-6
2791874(lab), 86-10-62782658(fax), [email protected] (e-mail)Yang, Xuanzong Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China 86-1
0-82649132(office), [email protected] (e-mail)Wang, Long Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China 86-10-826
49137(office), [email protected] (e-mail)Feng, Chunhua Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China 86-10-
82649132(office), [email protected] (e-mail)Gao, Zhe Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R.China, 86-10-
62776446(lab), 86-10-62782658(fax), [email protected] (e-mail)Wang, Wenhao Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R.China,
86-10-62776446(lab), 86-10-62782658(fax), [email protected] (e-mail)Xie, Lifeng Department of Engineering Physics, Tsinghua University, Beijing 100084, P.R.China, 86-1
0-62776446(lab), 86-10-62782658(fax), [email protected] (e-mail)
SUNIST spherical tokamak
SUNIST spherical tokamak
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SUNIST main parameters:
major radius R 0.3m
minor radius a 0.23m
Aspect ratio A ~1.3
elongation κ ~1.6
toroidal field ( R0) BT 0.15T
plasma current IP 0.05MA
flux (double swing) ΔΦ 0.06Vs
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SUNIST spherical tokamak magnets and power supply
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coil turn L(H) R(m) ID(kA) VC(V) Capacitor(mF)
TF 24 508 4.72 9.4 200 2560(1280)
HF 236 519 17.8 13 3000 13.3/1280
EF 26 684 15 1.5 1200/120 1(2)/476(18.8)
Vacuum vessel and BV magnet assembling
toroidal magnet pre-assembling
Cross section and designed magnetic surface
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SUNIST spherical tokamak vacuum and vacuum vessel
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main parameters – vacuum vessel:outer diameter 1.2 m
inner diameter 0.13 m
height 1.2 m
volume ~ 1 m3
surface area ~ 2.3 m2
vacuum pumps: TMP (1000l//s)
Sputtering Ti pump (200l/s)
wall conditioning: baking: PTC( Curie point 160 0C) glowing discharge,
siliconization
background pressure: ~ 6×10-5 Pa
leaking rate on cross seal: ≯@2×10-7 Pam3/s
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SUNIST spherical tokamak diagnostics and data acquisition
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Diagnosticselectromagnetic probes: 2 Rogowski probes, 9 flux loops (4 inside vessel)
15 2-D minor probes (13 in one poloidal cross section)
electrostatic probes: sets of movable 4 probes for Isi, Φ, and Vtoroidal
Data acquisition: 48 channel ADC: 32ch new, 16ch used in CT-6B
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Typical Discharge
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SUNIST spherical tokamak
Preliminary result
Remained questions
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Typical discharge of ECR startup
Preliminary result
Microwave: Pout ~ 100kW, t pulse ~ 30 ms, f = 2.45 GHz
background pressure < 110-5 Pascalhydrogen pressure ~ 110-2 Pascal during discharge
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Discharge with a group of plasma current peaks
Preliminary result
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Dependence of plasma current on vertical field
Preliminary result
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Electrode arrangement
Preliminary result
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Typical discharge with electrode assistance
Preliminary result
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Plasma current counteracted by electrode current
Preliminary result
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One special discharge with electrode assistance
Preliminary result
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Special discharges in CT-6B in 1997
Preliminary result
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Performances of preliminary ECR current startup
Preliminary result
Plasma current is just a peak ~ hundred millisecond of bottom width.
The dependence of driven plasma current on vertical field
is consistent with the toroidal plasma current by vertical field drift effect in ECR pl
asma.
Plasma current could increase above 10% (Fig. 7) in co-direction
Plasma current would be counteracted more obviously (Fig
.8), in counter-direction
We obtained one special discharge that the current of plasma and elec
trode is cutoff with on density and Iisat limitation, and the s
ame time scale of injected wave
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SUNIST spherical tokamak
Preliminary result
Remained questions
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Remained questions
Remained questions
This kind of plasma current peak is impossible to
develop to typical ST plasma current.
We didn't consider the mode conversion to EBW
in microwave launch system, then we faced the density
cut off problem of ECR wave propagated in plasma.
That is an only way to modification the feeding
line & antenna according to the request of mode
conversion to electron Bernstein wave.
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Remained questions
Remained questions
The discharge shown in Fig. 9 suggests that
there is a discharge regime with no limitations of
density cut off on ECR current startup and Ii-sat with
electrode discharge assistance.
The questions are why this regime exists and
how to find it for developing it from occasional event
to reproducible discharge.
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Remained questions
Remained questions
In preliminary experiments, the background
pressure of vacuum vessel increased from less
than 110-5 Pascal up to a balanced value, ~ 310-5
Pascal.
Driven plasma current decreased with the
increase of background pressure just like to scan
fuelling gas to higher pressure.
It is necessary to control wall condition for
further experiments.
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SUNIST- Sino UNIted Spherical Tokamak
Preliminary experiment of plasma current startup by ECR wave on SUNIST spherical tokamak
THANKS
JSPS-CAS Core University Program, 2005
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Vertical field effect on driving toroidal current
Preliminary result
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Toroidal field and ECR layer
Preliminary result