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The New Multifrequency Electron Cyclotron Resonance Heating System for ASDEX Upgrade

Dietmar Wagner, Fritz Leuterer, Adriano Manini, Francesco Monaco, Max Münich, François Ryter, Harald Schütz, Jörg Stober, Hartmut Zohm, Thomas Franke, Igor Danilov, Roland Heidinger, Manfred Thumm, Gerd Gantenbein, Walter Kasparek, Carsten Lechte, Alexander Litvak, Gregory Denisov, Evgeny Tai, Leonid Popov, Vadim Nichiporenko, Vadim Myasnikov, Elena Solyanova, Sergey Malygin, Fernando Meo, Paul Woskov

Fusion Science and Technology

Volume 52 / Number 2 / August 2007 / Pages 313-320


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A new multifrequency electron cyclotron resonance heating (ECRH) system is currently under construction at the ASDEX Upgrade tokamak experiment. This system will, for the first time in a fusion device, employ multifrequency gyrotrons, step-tunable in the range 105 to 140 GHz. In its final stage the system will consist of four gyrotrons with a total power of up to 4 MW and a pulse length of 10 s. The variable frequency will significantly extend the operating range of the ECRH system both for heating and current drive. The matching optics unit includes a set of phase-correcting mirrors for each frequency as well as a pair of broadband polarizer mirrors. The transmission line consists of nonevacuated corrugated HE11 waveguides with inner diameter of 87 mm and has a total length of ~70 m. A fast steerable launcher enables the steering of the beam over the whole plasma cross section poloidally. The first two-frequency gyrotron has been installed recently. It is equipped with a single-disk diamond window. The next gyrotrons will be step-tunable with two additional frequencies between 105 and 140 GHz. They will require a broadband output window, which will be either a Brewster or a double-disk window.

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