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Abstract. TRIAM-1M (
R0 = 0.8m,
a×b = 0.12m×0.18m and B = 8T) has the main mission to
study the route toward a high field compact steady state fusion reactor. We
have advanced steady state operation (SSO) programme in tokamaks, studied a
heating mechanism for the high ion temperature (HIT) mode with an internal
transport barrier, obtained an enhanced current drive (ECD) mode in an
extended (higher power and higher density) operation regime, performed
current density profile control experiments using multi-current drive
sys-tems and investigated effects of wall recycling, wall pumping and wall
saturation on particle control. In HIT mode a hysteresis relation between
Ti and
ne is found to be ascribed to different
timescales for
Ti and
ne to change. Excitation of
plasma waves corresponding to ion heating is studied by both measurements of
electromagnetic and electrostatic waves and their analysis. Achieved plasma
parameters in ECD are as follows;
ne is
4.3×1019m- 3 ,
ILHCD is
70kA,
Te and
Ti are 0.8 keV and 0.5 keV,
respectively, and the stored energy is 1.9 kJ. The energy confinement time
of 8-10 ms,
HITER89 - P
1.4, is
achieved and the current drive efficiency
=
ICDR0/PLH reaches
1×1019Am- 2/W at B = 7 T under the fully non-inductive
condition. Power threshold and hysteresis nature are studied.
Bi-directional current drive and superposed current drive experiments have
been carried out. In the former steady current reduction and peaking of j(r)
are observed, but it is noticed that self-organization of j(r) occurs above
a certain power ratio. In the latter broadening of j(r) can be obtained by
increasing superposed RF power, however, self-organization of j(r) also
occurs again at a certain power. Temporal behaviour of the recycling
coefficient with two different time constants (
3 s and
30 s)
is analysed. The wall pumping rates are evaluated to be
1.5×1016 atoms/s/
m2 for low
ne and
4×1017 atoms/s/
m2 for high
ne,
respectively. In the high power and high density experiments, the wall
saturation phenomenon affects the density control.
IAEA 2001