Big Step in EAST NBI: First MW High-current Ion Source

The first powerful high-current positive ion source recently got through its vacuum test, insulation test, plasma generator’s power supply system test, and static high voltage loading test, obtaining the first plasma at arc current of 900A for two seconds. This is a big step forward in EAST neutral beam injection (NBI) auxiliary heating project, a four-year national large-scale scientific project.

　  The filament power supply system (6V, 2.2kA), arc power supply system (50V) and suppression power supply system (-4kV) were applied during the static high voltage loading test, with power output 50kV and pulse width 500ms.

　  NBI heating is one of the most important auxiliary heating methods on tokamaks. The powerful high-current ion source is one of the key components of NBI system. To prepare themselves for undertaking the EAST-NBI project, EAST NBI team began their research on the powerful high-current ion source and related issues three years ago.

　  During the development of high-current ion source, the team established a close cooperation relationship with many domestic and international institutes, including Southwestern Institute of Physics (SWIP), General Atomics (GA) in the United States, National Institute for Fusion Science (NIFS) and Japan Atomic Energy Agency (JAEA) in Japan, Max Planck Institute of Plasma Physics (IPP) in Germany, and Budker Institute of Nuclear Physics (BINP) in Russia.

　  Through the collaborations, NBI team constructed the precise parts of megawatts positive ion source and mastered advanced manufacturing technologies for ion source, including solder formulation, loading fixtures, vacuum furnace welding process, and quality testing technology. Meanwhile, power supply system for plasma generator, measurement and data acquisition system, high voltage power supply system, the snubber system have been also built. All these work has laid a good foundation for the development of the powerful neutral beam injection system for EAST.

　  "This is just a phase advance for EAST NBI", said Prof Chundong HU, head of NBI team modestly. "More challenges are ahead of us. We will brave them one by one as we are a very young, give-it-all team."  (Liu Ling reports)