Speaker
Yongliang Li
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1109.pdf
Measurement of Neon impurity transport by ME-SXR diagnostic in the
EAST tokamak
Y. L. Li,1,2* G. S. Xu,1 K. Tritz,3 Y. Liang,1,2 X. Lin,1 H. Q. Liu,1 Q. Zang,1 T. Zhang,1 W.
Zhang,1 L. Wang,1 W. Feng,1 X. L. Li,1 and the EAST team
1
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China
Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung –
2
Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), 52425 Jülich, Germany
3
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland
21218, USA
*y.li@fz-juelich.de
The neon impurity transport has been analysed by multi-energy soft x-ray (ME-SXR)
diagnostic in the EAST tokamak. ME-SXR contains five arrays, of which one non-foil is
bolometric while four different foil filters (5 μm beryllium, Be, 15 μm Be, 25 μm Be and 50
μm Be foil) are used to measure the radiation spectrum of soft x-ray emitted by plasma. For
typical plasma temperature (~450 eV), the bolometer signal is dominated by L-shell emission,
while the 5, 15 and 25 μm Be filter arrays primarily measure K-shell lines and the 50 μm Be
array measures continuum emission from fully stripped neon. To study the neon transport, the
time derivative of the emissivity is introduced to describe the neon impurity transport. The
radial perturbation velocity of K-shell line emission emitted by neon impurity is measured about
40 m/s in H mode regime and is originally propagated near the separatrix along with forming
two perturbed emissivity peaks in the movement path. In contrast, the perturbation velocity of
continuum emission is much slower and is observed to begin to spread near the pedestal top.
The estimated electron pressure obtained by multiplying the electron density and electron
temperature, which is measured by POINT and ME-SXR respectively, shows that the pedestal
top pressure gradually decreases during the neon impurity propagating to the core plasma
region. The mitigation of edge localized modes is delayed for 20 ms after the neon injection,
after which the recovered ELM eruption time measured by the emissivity in 5 μm Be is twice
that in 50 μm Be array.
Reference
D J Clayton, et al., Plasma Phys. Control. Fusion 54 (2012) 105022
Y. L. Li, et al., Review of Scientific Instruments 86, 123512 (2015)
