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Gantenbein G.,Institute for Pulsed Power and Microwave Technology IHM | Dammertz G.,Institute for Pulsed Power and Microwave Technology IHM | Jelonnek J.,Institute for Pulsed Power and Microwave Technology IHM | Losert M.,Institute for Pulsed Power and Microwave Technology IHM | And 7 more authors.
14th IEEE International Vacuum Electronics Conference, IVEC 2013 - Proceedings | Year: 2013

This paper reports on a diamond Brewster angle window which has been used as a vacuum barrier in a 140 GHz step-frequency tunable high power gyrotron. This configuration ensures operation of the gyrotron at different frequencies without reflection of the RF power and provides excellent material properties of CVD diamond in the mm wave range. © 2013 IEEE. Source


Zhang J.,Institute for Pulsed Power and Microwave Technology IHM | Illy S.,Institute for Pulsed Power and Microwave Technology IHM | Gr Pagonakis I.,Institute for Pulsed Power and Microwave Technology IHM | Avramidis K.A.,Institute for Pulsed Power and Microwave Technology IHM | And 4 more authors.
Nuclear Fusion | Year: 2015

Emitter surface roughness is one of the important factors of electron beam degradation in magnetron injection gun (MIG) and the decrease of gyrotron efficiency. This paper surveys the influence of emitter surface roughness on the operation of the EU 1 MW 170 GHz gyrotron for ITER for two different gun designs. The emitter surface roughness was taken into account using a simple model. The ESRAY code was used for gun simulation and the EURIDICE code for calculation of the RF interaction in the cavity. The degradation of the beam quality due to the surface roughness is quantitatively studied and, furthermore, the influence on the gyrotron efficiency and the mode competition are investigated. Some dramatic phenomena, such as the generation of magnetically trapped electrons, are predicted at a very high level of roughness. © 2016 IAEA, Vienna. Source


Schmid M.,Karlsruhe Institute of Technology | Schmid M.,Institute for Pulsed Power and Microwave Technology IHM | Choudhury A.R.,Karlsruhe Institute of Technology | Choudhury A.R.,Institute for Pulsed Power and Microwave Technology IHM | And 25 more authors.
Fusion Engineering and Design | Year: 2013

Parasitic beam tunnel oscillations have been hampering the series production of gyrotrons for W7-X. This problem has now been overcome thanks to the introduction of a specially corrugated beam tunnel. Two gyrotrons equipped with the new beam tunnel have fully passed the acceptance tests. Despite excellent power capability, the expected efficiency has not yet been achieved, possibly due to the presence of parasitic oscillations suspected to be dynamic after-cavity-oscillations (ACI's) or due to insufficient electron beam quality. Both theoretical and experimental investigations on these topics are ongoing. On previous W7-X gyrotrons collector fatigue has been observed, not (yet) leading to any failures so far. The plastic deformation occurring on the collector has now been eliminated due to the strict use (on all gyrotrons) of a sweeping method which combines the conventional 7 Hz solenoid sweeping technique with a 50 Hz transverse-field sweep system. Starting in 2013, the gyrotron test facility at KIT will be enhanced, chiefly with a new 10 MW DC modulator, capable of testing gyrotrons up to 4 MW CW output power with multi-stage-depressed collectors. © 2013 Karlsruhe Institute of Technology (KIT). Source


Jelonnek J.,Karlsruhe Institute of Technology | Jelonnek J.,Institute for Pulsed Power and Microwave Technology IHM | Alberti S.,EURATOM | Avramidis K.,National Technical University of Athens | And 27 more authors.
2012 IEEE 13th International Vacuum Electronics Conference, IVEC 2012 | Year: 2012

ECH & CD is widely used in fusion plasmas. Gyrotrons are applied as power sources as they offer continuous wave operation at MW power level. This contribution reports on the status and plans of major projects of KIT towards high power gyrotrons, i.e. results from series production of the W7-X gyrotron, the development of the EU pre-prototype coaxial-cavity gyrotron, the 2 MW, 170 GHz CW coaxial cavity gyrotron for ITER and a frequency step-tunable gyrotron. © 2012 IEEE. Source


Malygin A.,Karlsruhe Institute of Technology | Malygin A.,Institute for Pulsed Power and Microwave Technology IHM | Illy S.,Karlsruhe Institute of Technology | Illy S.,Institute for Pulsed Power and Microwave Technology IHM | And 13 more authors.
2012 IEEE 13th International Vacuum Electronics Conference, IVEC 2012 | Year: 2012

In this paper, the design of a 10kW/28GHz gyrotron tube with an emitter ring based on a controlled-porosity reservoir (CPR) cathode is presented. CPR emitters provide significantly higher current density (up to 50 A/cm 2), as well as, longer life time (10 5 hours) than conventional emitters. The main goals of this experimental tube are to evaluate the use of CPR emitters for gyrotron applications, as well as to study the effect of non-uniform emission on gyrotron operation. © 2012 IEEE. Source

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