Upgrade of a 30kV/10mA anode power supply for triode type gyrotron

• Published in: Fusion engineering and design Vol. 96-97; pp. 597 - 601
• Main Authors: Siravo, Ugo, Alberti, Stefano, Dubray, Jérémie, Fasel, Damien, Hogge, Jean-Philippe, Marlétaz, Blaise, Marmillod, Philippe, Perez, Albert, Silva, Miguel
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2015
• Subjects: Gyrotron; High voltage; Phase-shift modulation; Power supply; TCV; Power supply; High voltage; Phase-shift modulation; Gyrotron; TCV
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2015.06.117

•Triode type gyrotron is fed by 3 power supplies: the main, an anode PS(APS) and a heater.•This paper presents the upgrade of 3APS, supplied in 1999, that never fulfilled the specs.•The new working principle is very efficient, easy to implement, for a minimal cost.•Upgraded APS provides extended modulation capabilities, no overshoot and lowerripple.•This upgrade will allow exploring new operation regimes for the 3 TCV X3 gyrotrons.
The RF power of a gyrotron with a triode type magnetron-injection-gun (MIG) can be directly controlled via the voltage applied between its anode and its cathode. Hence, the performance of this type of gyrotron relies directly on the possibilities offered by the power supply controlling the anode to cathode voltage. For a system of gyrotrons connected to the same main high-voltage power supply, with a triode MIG one has the additional advantage of independently controlling each individual gyrotron.
This paper presents the modifications brought to the three existing 30kV/10mA anode power supplies connected to the 500kW/118GHz/2s X3 gyrotrons operated on the TCV Tokamak. The new working principle based on phase-shift modulation (PSM) is described in detail. Experimental results obtained on dummy load are compared to simulations performed during the design phase. With respect to the initial working principle, the modulation frequency capability has been increased by a factor 10 reaching more than 5kHz, whereas the output voltage ripple as well as the overshoot/undershoot have been significantly reduced.