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SUNISTSUNIST
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
The 3rd IAEA TCM on Spherical Torus and the 11th STW, St. Petersburg
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) .
OUTLINE
UNISTUNISTSUNISTSUNIST
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
SUNIST spherical tokamak
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
SUNIST spherical tokamak
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
SUNIST spherical tokamak
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
SUNIST spherical tokamak
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Typical Discharge
SUNIST spherical tokamak
OUTLINE
UNISTUNISTSUNISTSUNIST
SUNIST spherical tokamak
Preliminary result
Remained questions
SUNISTSUNIST
Typical discharge of ECR startup
Preliminary result
Microwave: Pout < 100kW, t pulse ~ 30 ms, f = 2.45 GHz
background pressure ~ 110-4 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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Performances of preliminary ECR current startup
Preliminary result
Plasma current is just spikes ~ hundreds millisecond of bottom width
when the plasma existed during wave injecting from the lightening signal.
The dependence of driven IP on vertical field is consistent with
the toroidal plasma current by vertical field drift effect in ECR plasma.
IP could increase above 10% (Fig. 7) in co-direction,
IP would be counteracted more obviously (Fig.8), in counter-
direction with electrode discharge assistance.
We obtained one special discharge that the currents of plasma and
electrode are cutoff and extended to wave timescale.
OUTLINE
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SUNIST spherical tokamak
Preliminary result
Remained questions
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Remained questions
Remained questions
This kind of plasma current spike is impossible
to develop to typical ST plasma current.
It is necessary to rearrange launch system of
microwave for better coupling to plasma.
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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 110-4 Pascal up to a balanced value, ~ 310-4
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.
SUNISTSUNIST
SUNIST- Sino UNIted Spherical Tokamak
Preliminary experiment of plasma current startup by ECR wave on SUNIST spherical tokamak
THANKS
The 3rd IAEA TCM on Spherical Torus and the 11th STW, St. Petersburg
SUNISTSUNIST
about central solenoid - Is it impossible to keep?
A questions
hard mode save mode
too high J CS,then stress,thermal load in high neutron
moderate J CS, just operating very short time
Impossible to keep ?
problem
operation mode
conclusion