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Internal electrostatic and magnetic measurement in SUNIST

The Second A3 Foresight Workshop on Spherical Torus , Jan . 6-8, 2014, Tsinghua University, Beijing, China. Internal electrostatic and magnetic measurement in SUNIST. S. Chai ， W. H. Wang. Department of Engineering Physics, Tsinghua University, Beijing, P. R. China .

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Internal electrostatic and magnetic measurement in SUNIST

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  1. The SecondA3 Foresight Workshop on Spherical Torus, Jan. 6-8, 2014, Tsinghua University, Beijing, China Internal electrostatic and magnetic measurement in SUNIST S. Chai，W. H. Wang Department of Engineering Physics, Tsinghua University, Beijing, P. R. China * E-mail: chaisong@sunist.org

  2. Layout of the Windows Top view of SUNIST Langmuir probes Toroidal magnetic probes array & flux loops Poloidal magnetic probes array Moveable inner Langmuir & magnetic probe Moveable multi-probes The magnetic probes

  3. Langmuir Probes(1) • Probe design --Total movable distance • ~13 cm ( 0.78a ~ 1.35a) --Tips configuration • 4 tips: 2 float, 2 connected for Isi • Material: Mo • Typical results -- ne, Te, fp, and ff -- Shot by shot scanning Tips configuration Picture of the probe Wang W. H., et al., PPCF 2005 Typical results

  4. Moveable Langmuir-magnetic Probe(2) • An integrated probe -- A magnetic probe -- A 4 tips Langmuir probe set • Purpose -- To get localplasma pressure and magnetic pressure simultaneously • Future plan -- Smaller size, more “local” 2013 Raw signals from the Langmuir-magnetic probe The moveable Langmuir-magnetic probe

  5. Moveable Multi-probes (3) 38*20*20mm Parameters of 4 tips Langmuir probe: L=3mm,d=1mm ,Ap=10.21mm2 Langmuir Probe Parameters of magnetic probe: N=310, d=10mmS=78.5mm2 NS=0.0243m2 Magnetic Probe Entrance slit: 5mm*0.4mm Mesh Aperture: 0.2mm Retarding-field Energy Analyzer（RFEA） Drawing of moveable multi-probes

  6. Retarding-field Energy Analyzer Volt-ampererelationship(2) Principle of the RFEA(1) The relationship between collected Isi and scan potential: -250V 300V 27V (1):Ion velocity distributions at the tokamak edge; R.A.Pitts; 31 May 1991 (2):W.H.Wang;

  7. Test Result a *20V b Vf1 *20V Vf2 Location of probe Bp10 A Experimental result of magnetic probe; b Experimental result of Langmuir probe; *100mA Isi

  8. Furtherwork RFEA: radial profile of Ti Magnetic Probe: radial profile of Bp Langmuir probe: radial profile of Ne,Te Bootstrap currentdensity: John Wesson,《TOKAMAK》, chapter 4.9 Moveable multi-probes Bootstrap current

  9. Summary Internal electrostatic and magnetic measurement in SUNISTincludes： A set of Langmuir probe: On one side of the vacuum chamber Toroidal and poloidal magnetic array & flux loops: EFIT, displacement, feedback control… A set of moveable magnetic & Langmuir probes: On the other sideofthe vacuum chamber A set of moveable multi-probes: Profile of Te, Ti, Ne, bootstrap current…

  10. Thankyouforyourattention!

  11. 技术难点 狭缝的尺寸：足够小，不大于2倍的鞘层厚度，6-8倍的德拜长度 SUNIST上的一些参数：Te=20eV，Ne=3*1018m-3 钨钼合金（绝缘、抗热震、高热材料，但难开缝，需用等体切割） 厚度0.5mm，切口长*宽 （3~5mm*0.1mm） 栅网孔径：要求离子通过时整个栅网等电位， ni’为分析器内部离子密度，由于分析器内密度远小于外部，所以这个条 件比较容易满足。材料为钼丝，网孔径200um 收集板：纯铜 电源：低频功率源 频率高于50kHz，功率在几十kw量级，扫描电压正负250V HA-405A 高压放大器 最高频率500kHz，扫描电压0~400V Entrance slit: 5mm*0.4mm Mesh Aperture: 0.2mm 聚四氟乙烯 Teflon Here, plasma potential outside the RFEA; niion density; Cs the ion-acoustic velocity; A is the slit window area; TT is the total transmission coefficient. So

  12. 磁探针测得的磁场变化情况 磁探针测得的磁场变化图像 T=47~52ms测得的Ne、Te和Bp的值

  13. j a k k e, f, h k k c d, g, i

  14. Progress of AW experiments Toroidal Field Coils Antenna 4 Plasma Torus Antenna 1 • Cryogenic Pump, Ion Sputtering Pump TMP Photodiodes, NaI Detector Fast Visible Camera 2.45 GHz Pre-ionizer Antenna 2 Antenna Strap Feedthrough BN Limiters Antenna 3 Piezo-valves CdZnTe Detector 94 GHz Interferometer Topview of SUNIST Antennas and the plasma torus

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