29th Symposium on Fusion Technology (SOFT 2016)

P4.035 Development of wideband solid state power amplifier for ICH & CD RF source

8 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 35

Poster B. Plasma Heating and Current Drive P4 Poster session

Speaker

Manojkumar Patel (ICH&CD)

Description

ITER-India is developing Ion Cyclotron Heating & Current Drive (ICH&CD) RF source in the frequency of 35 to 65 MHz. Three cascaded amplifiers along with low power RF section, AC/DC power supplies and controls will be used for getting MW level RF power from one source. In the present configuration, two tube based tuned amplifiers, i.e. driver (~150 kW) and final (1.7MW) stage amplifiers are driven by a wideband solid state power amplifier (~ 10 kW). Development of such solid state power amplifier (SSPA) with required ±1.5 dB gain flatness in the above frequency range is very challenging, due to unique design of combiner and output matching circuit. This development is also aiming for achieving compact modular design, higher efficiency, usage of low voltage power supplies and better MTBF value compared with tube based amplifier of similar specification. Since 10 kW is needed as input power to the driver stage amplifier, the design goal for SSPA is to achieve power level of around 12 kW/CW. Considering losses in the combiner, total 16 pallet amplifier modules, each having capability of 1kW are to be combined using 16X1 wideband combiners. Each pallet amplifier module is designed using LDMOS transistors (MRFE6VP61K25H), which is capable to deliver 1250 W CW power in the required frequency range with adequate tune matching circuits. For input matching 9:1 ferrite based balun is used. For output circuit, 1:9 impedance transformation & balance to unbalance quarter wave transformer is used. For gate and drain supply voltages, adequate filters are designed and installed. In this paper, detail design and development of single pallet amplifier module as a part of wide band Solid State Power Amplifier will be discussed along with test results. Further, upcoming plan for integration of 16 such pallet modules with controls and monitoring system will be discussed.