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Abstract. Significant progress in obtaining high performance discharges
for many energy confinement times in the DIII-D tokamak has been realized
since the previous IAEA meeting. In relation to previous discharges,
normalized performance 10 has been sustained for
> 5
with
qmin > 1.5. (The normalized performance is measured by the product
H89 indicating the proximity to the conventional
limits and energy confinement quality, respectively.) These H-mode
discharges have an ELMing edge and
5%. The limit to
increasing
is a resistive wall mode, rather than the tearing modes
previously observed. Confinement remains good despite the increase in q. The
global parameters were chosen to optimize the potential for fully
non-inductive current sustainment at high performance, which is a key
program goal for the DIII-D facility in the next two years. Measurement of
the current density and loop voltage profiles indicate
75% of the
current in the present discharges is sustained non-inductively. The
remaining ohmic current is localized near the half radius. The electron
cyclotron heating system is being upgraded to replace this remaining current
with ECCD. Density and
control, which are essential for operating
advanced tokamak discharges, were demonstrated in ELMing H-mode discharges
with
H89
7 for up to 6.3 s or
34
.
These discharges appear to be in resistive equilibrium with
qmin
1.05, in agreement with the current profile relaxation time of 1.8 s.
IAEA 2001