The ITER electron cyclotron heating (ECH) transmission lines (TLs) are 63.5-mm-diam corrugated waveguides that will each carry 1 MW of power at 170 GHz. The TL is defined here as the corrugated wav...

Loss estimate for iter ech transmission line including multimode propagation

Status and future development of Heating and Current Drive for the EU DEMO

Extension of steering angle in a square corrugated waveguide antenna

High power, long pulse millimeter (mm) wave experiments of the RF test stand (RFTS) of Japan Atomic Energy Agency (JAEA) were performed. The system consists of a 1 MW/170 GHz gyrotron, a long and short distance transmission line (TL), and an equatorial launcher (EL) mock-up. The RFTS has an ITER-relevant configuration, i.e., consisted by a 1 MW-170 GHz gyrotron, a mm wave TL, and an EL mock-up. The TL is composed of a matching optics unit, evacuated circular corrugated waveguides, 6-miter bends, an in-line waveguide switch, and an isolation valve. The EL-mock-up is fabricated according to the current design of the ITER launcher. The Gaussian-like beam radiation with the steering capability of 20°–40° from the EL mock-up was also successfully proved. The high power, long pulse power transmission test was conducted with the metallic load replaced by the EL mock-up, and the transmission of 1 MW/800 s and 0.5 MW/1000 s was successfully demonstrated with no arcing and no damages. The transmission efficiency of the TL was 96%. The results prove the feasibility of the ITER electron cyclotron heating and current drive system.

High power millimeter wave experiment of ITER relevant electron cyclotron heating and current drive system.

Electron cyclotron resonance heating (ECRH) is the main heating system for W7-X. A 10-MW ECRH plant with continuous wave (cw) capability is under construction to support the W7-X operation, which aims at demonstrating the steady-state capability of stellarators at reactor-relevant plasma parameters. The ECRH system consists often radio-frequency (rf) modules with 1 MW power each at 140 GHz. The rf beams of the individual gyrotrons are transmitted in common to the W7-X torus via open multibeam mirror lines. The losses of individual components of the transmission system were measured with both low- and high-power methods. Integrated full-power, cw measurements of the long-distance transmission losses are reported and compared to theoretical design estimates.

/pdf/ecrh-for-w7-x-transmission-losses-of-high-power-140-ghz-wave-39be2hq1h7.pdf

ECRH for W7-X: Transmission losses of high-power 140 GHz wave beams

For the upper ECW launcher on ITER, the use of a “remote steering antenna” based on the imaging properties of rectangular waveguides is planned. To characterise launchers of this type, low-power experiments on a 4-side corrugated square waveguide with a scanning mirror at the input of the waveguide were performed in the frequency range of 140 to 160 GHz. It is shown, that elliptical polarisation needed for ECCD can be transmitted without depolarisation. The usable steering range of the antenna is at least -10” < cp 5 +lo”. Experiments with the scanning plane in the diagonal of the square waveguide led to a negligible increase the scanning range, and lobes in the upward and downward direction are detected at larger scanning angles. Mitre bends can be integrated into the waveguide without prohibitive extra loss, which is demonstrated by far-field measurements. Detailed calorimetric measurements for this set up confirm this statement for the polarisation perpendicular to the scanning plane, whereas extra loss is measured for the parallel polarisation. Results are discussed and are compared to theory.

Performance of a remote steering antenna for ECRH/ECCD applications using 4-Wall corrugated square wave-guide

The transmission system for ECRH on the stellarator W7-X: design issues and tests of prototype components

For the future stellarator W7-X of IPP at Greifswald, a powerful electron cyclotron resonance heating facility is being built which will include 10 gyrotrons at 140 GHz with a CW power of 1 MW each plus 2 optional gyrotrons at 70 GHz. The millimetre wave power will be transmitted fully optically via two multiple-beam waveguides (MBWG) with a length of about 50 m. This paper presents calculations and low-power measurements of the transmission characteristics of a prototype MBWG, which promise a high transmission efficiency for the ECRH system under construction.

https://ieeexplore.ieee.org/iel5/7598/20722/00958851.pdf

Performance of the 140 GHz prototype transmission system for ECRH on the stellarator W7-X

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ECRH for W7-X: Transmission losses of high-power 140 GHz wave beams

Performance of a remote steering antenna for ECRH/ECCD applications using 4-Wall corrugated square wave-guide

The transmission system for ECRH on the stellarator W7-X: design issues and tests of prototype components

Performance of the 140 GHz prototype transmission system for ECRH on the stellarator W7-X