Speaker
Gregor Birkenmeier
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1020.pdf
Requirements for an Imaging Heavy Ion Beam Probe at ASDEX Upgrade
G. Birkenmeier1,2 , J. Galdon-Quiroga1,3 , J. F. Rivero-Rodriguez3 , M. Garcia-Munoz1,3 ,
M. Griener1 , G. Harrer4 , N. Leuthold1 , E. Wolfrum1 , U. Stroth1,2 , and the ASDEX Upgrade Team.
1 Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
2 Physik-Department E28, Technische Universität München, 85748 Garching, Germany
3 Department of Atomic, Molecular and Nuclear Physics, University of Seville, 41012 Seville,
Spain
4 Institute of Applied Physics, TU Wien, Vienna, Austria
We present a conceptual study and hardware investigations in preparation of an imaging
heavy ion beam probe (i-HIBP) for the ASDEX Upgrade tokamak [1]. The main feature of this
new type of a heavy ion beam probe (HIBP) is the imaging of the secondary beams by means of
an in-vessel scintillator screen in combination with a high speed camera. The spatio-temporal
pattern on the scintillator contains two-dimensional information about the plasma density, the
plasma potential and the poloidal magnetic field at the points of ionization of the primary beam,
where the secondaries are created. Due to the use of a neutral beam as primary beam and the
in-vessel imaging of the secondaries, the i-HIBP system is much more compact than a classical
HIBP [2] consisting of large accelerators and bulky electrostatic energy analyzers.
A numerical study for a neutral 80 keV cesium beam as primary beam has shown [1], that
information about the density, the plasma potential and the poloidal magnetic field from 10 cm
inside the last closed flux surface up to the far scrape-off layer can be obtained for a typi-
cal low-density ASDEX Upgrade plasma. The variation of the pattern on the scintillator has
shown to depend linearly on the perturbation amplitude of the measured quantities, and local-
ized measurements of plasma potential fluctuations down to 10 eV seem possible if certain
beam properties are fulfilled.
Laboratory tests with a neutral cesium beam and a scintillator material, which is typically
used in fast ion loss detectors [3], have shown that we can meet all necessary requirements for a
high measuring sensitivity of an i-HIBP at ASDEX Upgrade. We present details of the planned
technical implementation and show the capabilities of this new diagnostic for investigations of
plasma edge phenomena like edge localized modes, zonal flows, geodesic acoustic modes and
blob filaments.
References
[1] J. Galdon-Quiroga et al., Journal of Instrumentation 12, C08023 (2017)
[2] A.V. Melnikov et al., Nucl. Fusion 57, 072004 (2017)
[3] M. Garcia-Munoz et al., Rev. Sci. Instrum. 80, 053503 (2009)
