Speaker
Dániel Imre Réfy
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1019.pdf
Atomic Beam Probe diagnostic for plasma edge current measurements at
COMPASS
D. I. Réfy1, P. Hacek2,3, S. Zoletnik1, D. Dunai1, G. Anda1, M. Lampert1, M. Aradi4, A.
Bencze1, M. Berta5, J. Krbec2,6, V. Weinzettl2, R. Panek2 and the COMPASS Team2
1
Wigner RCP, Budapest, Hungary, 2Institute of Plasma Physics of the CAS, Prague, Czech Republic, 3Faculty
of Mathematics and Physics, Charles University, Prague, Czech Republic, 4Graz University of Technology,
Fusion@ÖAW, Austria, 5Széchenyi István University, Győr, Hungary, 6Faculty of Nuclear Sciences and
Physical Engineering, CTU, Prague, Czech Republic
The measurement of the plasma edge current density distribution and temporal evolution
during the edge localized mode (ELM) cycle is of particular interest on the field of
magnetically confinement plasmas, since the theoretical models recognize it as a key element
for the trigger mechanism of the ELMs. The atomic beam probe (ABP [1]) is an extension of
the beam emission spectroscopy (BES) diagnostic [2]. The beam atoms are ionized due to the
collision with the plasma particles, deflected through a curved path due to the magnetic field
and may be detected close to the wall of the machine. The arrival location and intensity of the
ions carry information about the toroidal plasma current distribution, the density profile and
the electric potential in the plasma.
Detecting the few microampere ion current close to the plasma edge requires a special
detector. The measurements with a preliminary test detector head has been carried out, and a
final detector head design was proposed based on the results [3]. A new detector head for the
ABP was designed and tested in the lab. The new setup utilizes a shallow Faraday cup matrix,
produced with printed-circuit board technology, and double mask for secondary electron
suppression. Noise characterization, switching time, cross talk and fluctuation sensitivity test
results in the lab setup will be presented, along with the first measurement results with the
new setup at COMPASS tokamak [4].
[1] M. Berta et al., Development of atomic beam probe for tokamaks, Fus. Eng. Des. 88 (2013) 2875
[2] G. Anda et al., Lithium beam diagnostic system on the COMPASS tokamak. Fus. Eng. Des. 108 (2016)
[3] P. Hacek et al., Measurements with ABP Diagnostic on the COMPASS Tokamak, WDS'15 proceedeings (2015)
[4] R. Panek et al., Plasma Phys. Control. Fusion 58 014015 (2016)
