Reflectometry with wavelengths in the centimetre to millimetre-wave range will be used in ITER to measure the density profile in the main plasma and divertor regions and to measure the plasma position and shape in order to provide a reference for the magnetic diagnostics in long pulses. In addition, it is expected to provide key information for the measurement of density fluctuations. A set of reflectometers to meet the relevant ITER measurement requirements has been included in its present outline as part of the ITER design since 2001 and is being adapted to the present ITER baseline and to accommodate progress with reflectometry techniques and measurement capabilities. It comprises low and high field side (HFS and LFS, respectively) ordinary (O-) mode systems for the measurement of the density profile in the gradient regions, a LFS extraordinary (X-) mode system for the detailed study of the edge profile, an HFS X-mode system operating in the left hand cutoff to measure the core profile, a dedicated O-mode system for plasma-wall gap measurement and a multi-band, multiple line of sight O-mode system to measure divertor density profiles. This paper describes the evolution of the design, in particular some recent improvements in the engineering implementation and improvements aimed at enhancing the measurement capability. It concludes with a brief assessment of the likely measurement performance against the ITER measurement requirements for the parameters of interest and the overall confidence that the technique will be implanted on ITER.

Results of the electron cyclotron current drive experiment at the second harmonic resonance on the T-10 tokamak are presented. High frequency (HF) power up to 1.2 MW was launched from the low field side. A maximum driven current of 35 kA and current drive efficiency ηCD = 0.05 A/W at an electron temperature Tc(O) = 4 keV and a density nc(0) = 1 × 1013 cm-3 were obtained. For low HF power, the current drive efficiency was less than predicted by the linear theory unless the effect of the elliptical polarization from non-perpendicular injection is considered, in which case the efficiency is close to the theoretical value. The experimental dependence of HF on the absorbed HF power indicated a strong increase of ηCD with power. Suppression of sawtooth oscillations and improvement of confinement during electron cyclotron heating has also been demonstrated

The present paper reports on the recent development of several oversized millimeter wave transmission line components for different applications. The studies include a circular TE 11 -to-Gaussian beam mode converting horn, a TM 01 -to-rotating TE 31 mode converter, a TE 11 -mode 90°bend, a series of different HE 11 -mode transmission line components, a notch filter and a fast laser controlled semiconductor microwave switch.

We describe the design and test results of the transmission line for liquid-state (LS) and solid-state (SS) DNP spectrometers with the second-harmonic 258.6 GHz gyrotron at the Institute of the Biophysical Chemistry Center of Goethe University (Frankfurt). The 13-meter line includes a mode converter, HE11 waveguides, 4 mitre bends, a variable polarizer-attenuator, directional couplers, a water-flow calorimeter and a mechanical switch. A microwave power of about 15 W was obtained in the pure HE11 mode at the spectrometer inputs.

No abstract