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. 1.
Overview of TCV results
2001
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. 1.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
