Speaker
Antti Timo Olavi Snicker
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1067.pdf
Neutral beam ion shine-through calculations for the reduced field and
current plasmas in ITER
A. Snicker1 , K. Särkimäki1 , J. Varje1 , M. Schneider2 , A. Polevoi2
1 Aalto University Department of Engineering Physics, Otakaari 1, 02015, Espoo, Finland
2 ITER organization, Route de Vinon-sur-Verdon, CS90046, 13067 St Paul-lez-Durance,
France
ITER research plan includes Pre-fusion Power operation (PFPO) phases that plan an operation
with reduced fields and currents. The aim of the reduced field and current operation is to have
an H-mode access in H and He plasmas. This is important since the predictions of the threshold
power by extrapolating empirical scaling laws are uncertain and because only limited amount
of heating power will be available.
In the second phase of the PFPO, a neutral beam ion (NBI) operation is expected. The access
to H-mode favors operation in low electron density, on the other hand the NBI shine-through
poses a lower limit to electron density. Fortunately, the NBI system can be operated with lower
voltage (=lower injection energy). The aim of this contribution is to assess the limits of the
NBI system in the PFPO in terms of the shine-through. This is done by carrying out beamlet-
based NBI simulations and calculating the shine-through heat power load at the wall structures,
especially to the so called shielding block that locates under the first-wall panels and will get
significant heat load from gaps between the blanket modules and thus will be the first structure
exceeding engineering limits in terms of heat power load.
The injection energy of the NBI system cannot be changed arbitrarily due to beam perveancy
2.5 , where E
considerations. Namely, the power needs to be scaled according to PNBI ∝ Einj inj is
the injection energy and PNBI the NBI power. In the simulations with the hydrogen beams into
helium plasmas it was observed, however, that the shine-through power depends much stronger
3.9 , where P is the
on the injection energy than beam perveancy condition, namely PST ∝ Einj ST
shine-through power (or the power load at the critical shielding block element). This study will
be utilized to guide the operational window and maximum NBI pulse duration in the ITER
PFPO phase. The results will be compared against earlier studies such as [1].
References
[1] M.J. Singh et al., New J. Phys. 19, 055004 (2017)
