A Probe Head for Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma

In ASDEX Upgrade (AUG) electrostatic and magnetic fluctuations in the edge plasma region were measured simultaneously during ELMy H-mode (high confinement) plasmas and L-mode (low confinement) plasmas and during a transition between the two modes. A special probe was used containing six Langmuir probe pins of graphite of which one is protruding radially. In addition, 20 mm behind the front side a triple magnetic pick-up coil is mounted inside the probe head by which temporal variations of the magnetic field in all three directions of space can be detected. The probe pins are arranged in such a way that simultaneously the poloidal and radial electric field components, the ion saturation current and the current-voltage characteristic can be registered. During the AUG discharges of 7 s lengths the probe head is inserted two to three times for 100 ms each by the midplane manipulator into the scrape-off layer outside the last closed flux surface. The main emphasis is put on type I ELMs and from the results the radial turbulent particle flux and magnetic field variations are determined.

[1]  小倩,et al.  Fusion Rings for Degenerate Minimal Models , 2002 .

[2]  R. Schrittwieser,et al.  Application of emissive probes for plasma potential measurements in fusion devices , 2001 .

[3]  E. Wolfrum,et al.  The filamentary structure of ELMs in the scrape-off layer in ASDEX Upgrade , 2007 .

[4]  J. Allen.  A paradox re-examined , 1983 .

[5]  D. N. Hill,et al.  A review of ELMs in divertor tokamaks , 1997 .

[6]  V. Rohde,et al.  Direct measurements of the plasma potential in ELMy H-mode plasma with ball-pen probes on ASDEX Upgrade tokamak , 2009 .

[7]  T. Eich,et al.  Filament structures at the plasma edge on MAST , 2006 .

[8]  E. Powers.  Spectral techniques for experimental investigation of plasma diffusion due to polychromatic fluctuations , 1974 .

[9]  G. Matthews,et al.  The fine structure of ELMs in the scrape-off layer , 2005 .

[10]  S. Zweben.  Principles of Plasma Diagnostics , 1990 .

[11]  Guido Van Oost,et al.  Measurements with an emissive probe in the CASTOR tokamak , 2002 .

[12]  A. Loarte,et al.  Assessment of erosion of the ITER divertor targets during type I ELMs , 2003 .

[13]  Thomas Klinger,et al.  Laser-heated emissive plasma probe. , 2008, The Review of scientific instruments.

[14]  L. Horton,et al.  Survey of Type I ELM dynamics measurements , 2006 .

[15]  W. Fundamenski,et al.  Blob/hole formation and zonal-flow generation in the edge plasma of the JET tokamak , 2009 .

[16]  R. Schrittwieser,et al.  Turbulence and transport measurements with cold and emissive probes in ISTTOK , 2008 .

[17]  V. Rohde,et al.  Current filaments in turbulent magnetized plasmas , 2009 .

[18]  H. Zohm.  Edge localized modes (ELMs) , 1996 .

[19]  G. Oost,et al.  Comparative measurements of the plasma potential with the ball-pen and emissive probes on the CASTOR tokamak , 2005 .

[20]  R. Neu,et al.  Structure and dynamics of spontaneous and induced ELMs on ASDEX Upgrade , 2008 .

[21]  R. Lathe.  Phd by thesis , 1988, Nature.