preliminary experiment of plasma current startup by ecr wave on … · 2005. 10. 11. ·...

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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

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) .

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SUNIST spherical tokamak

Preliminary result

Remained questions

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SUNIST United Laboratoryfounded in 2004, consists of Department of Engineering Physics, Tsinghus University (DEP) ; Institute of Physics, Chinese Academy of Science (IOP) and keeping very close collaboration with Southwestern Institute of Physics (SWIP) and Institute 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-

62791874(lab), 86-10-62782658(fax), [email protected] (e-mail)Yang, Xuanzong Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China 86-10-

82649132(office), [email protected] (e-mail)Wang, Long Institute of Physics, Chinese Academy of Science, Beijing 100080, P.R.China 86-10-

82649137(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-

10-62776446(lab), 86-10-62782658(fax), [email protected] (e-mail)



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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 magnets and power supply


1(2)/476(18.8)1200/1201.51568426EF

13.3/128030001317.8519236HF

2560(1280)2009.44.7250824TF

Capacitor(mF)VC(V)ID(kA)R(mΩ)L(μH)turncoil

Vacuum vessel and BV magnet assembling

toroidal magnet pre-assembling

Cross section and designed magnetic surface


SUNIST spherical tokamak vacuum and vacuum vessel

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main parameters – vacuum vessel:outer diameter 1.2 m inner diameter 0.13 mheight 1.2 mvolume ~ 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 Paleaking rate on cross seal: ≯2×10-7 Pam3/s


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 VtoroidalData acquisition: 48 channel ADC: 32ch new, 16ch used in CT-6B


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Typical Discharge


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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 GHzbackground pressure ~ 1×10-4 Pascalhydrogen pressure ~ 1×10-2 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.

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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 1×10-4 Pascal up to a balanced value, ~ 3×10-4

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.

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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

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about central solenoid - Is it impossible to keep?

A questions

hard mode save modetoo high J CS,then stress,thermal load in high Φ neutronmoderate J CS, just operating very short time

Impossible to keep ?

problem

operation mode

conclusion

preliminary experiment of plasma current startup by ecr wave on … · 2005. 10. 11. ·...

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