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Abstract. The TCV tokamak (
R = 0.88m,
a < 0.25m,
BT < 1.54T)
is equipped with six 0.5MW gyrotron sources operating at 82.7 GHz for
second harmonic X-mode ECH. By distributing the ECCD current sources over
the discharge cross section, fully driven stationary plasmas with
Ip = 210kA,
ne0 = 2×1019m- 3,
Te0 4keV,
were obtained for the full discharge duration of 2s. Highly peaked electron
temperature profiles with
Te0 up to 12keV were obtained in central
counter current drive scenarios with off-axis ECH. Absorption measurements
using a 118 GHz gyrotron have demonstrated the importance of suprathermal
electrons for third harmonic absorption. A coupled heat-particle transport
phenomenon known as ``density pumpout'', which leads to the expulsion of
particles from the plasma core, has been linked to the presence of m=1
modes, suggesting that it is due to the existence of locally trapped
particles associated with the loss of axisymmetry. Highly elongated
discharges have been developed with Ohmic heating (
< 2.8) and
off-axis ECH. The latter exhibit considerably improved vertical stability
due to current profile broadening. A ``gateway'' for Elmy H-modes has been
discovered, which allows stationary Ohmic ELMy H-mode operation in over
wide range of elongation, triangularity and density. Divertor detachment
experiments suggest the existence of recombination pathways other than
three-body or radiative processes.
IAEA 2001