Speaker
Yury Gribov
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1075.pdf
Progress in simulation of ITER First Plasma operation
Y.Gribov1, A.A.Kavin2, V.E.Lukash3, K.M.Lobanov2, A.B.Mineev2,4,
M.L.Dubrov3, R.R.Khayrutdinov3, J. A. Snipes1, P.C. de Vries1
1
ITER Organization, CS 90 046, 13067 St. Paul-lez-Durance, France
2
Joint Stock Company “NIIEFA” Saint Petersburg, Russia
3
NRC Kurchatov Institute, Moscow, Russia
4
Saint Petersburg State University, Saint Petersburg, Russia
This paper presents a progress in simulation of ITER First Plasma operation since it was
reported in [1]. New 0D plasma transport study was performed assuming hydrogen gas and Fe
as a single impurity (stainless steel limiter), taking into account the Dreicer mechanism of
runaway electron generation and their avalanche multiplication. The Fe influx to the plasma
was described by physical sputtering of the limiter due to the wall bombardment by hydrogen
and Fe ions. It was shown that the gas pressure lower limit, ≈ 0.3 mPa, is defined by the
generation of runaway electrons. The gas pressure upper limit, ≈ 0.7 mPa (obtained using rather
optimistic assumption - the plasma minor radius ≈ 1.6 m), is defined by insufficient ionization
of the Fe impurity (“uncompleted burnthrough”). With the increase of the prefill gas pressure to
values higher than this upper limit (e.g. to 0.75 mPa), the maximum value of the plasma current
reduces very fast to less than 0.05 MA. The pressure upper limit reduces with reduction of the
plasma minor radius.
A set of the First Plasma scenarios were designed using the TRANSMAK code and
simulated with the DINA code (free boundary plasma equilibrium, 0D plasma transport with
steel limiters). Two scenarios were designed with the goal of formation at the gas breakdown a
large area with the magnetic field null. Such “wide null” magnetic configuration is preferable
for the Ohmic gas breakdown. In one scenario the center of the breakdown region was located
at R = 5.7 m, Z = 0. In another scenario, the center of the breakdown region was shifted
vertically by 1.5 m (R = 5.7 m, Z = 1.5 m). Another two scenarios of PF system operation were
designed to get at the gas breakdown in the breakdown region vertical magnetic field
Bz ≈ 1.5 mT and 2.5 mT corresponding to the “Shafranov” field of plasmas with the currents
0.03 MA and 0.05 MA, respectively. Such magnetic configurations may be preferable for
plasma initiation with ECRF assist. The simulations take into account the vertical magnetic
field produced by magnetized steel rebar of the Tokamak Complex producing at First plasma
operation about 10 mT of vertical magnetic field opposite to the direction of “Shafranov” field.
[1] A.B.Mineev, et al., Study of ITER First Plasma initiation using a 3D electromagnetic model, 25th IAEA Fusion
Energy Conference, St. Petersburg, Russia, 2014, PPC/P3-20.
