Neutral beam injection (NBI) is one of the most effective tools of four auxiliary plasma heating methods for fusion plasma heating and current driven. Now, a next generation fusion device, China Fusion Engineering Test Reactor (CFETR) is under design, and a giant negative neutral beam injector (NNBI) will be developed is foreseen. In order to demonstrate the key technology and performance of negative ion source, a negative RF ion source test facility has been developed since 2017 in the Institute of Plasma Physics, Chinese Academy of Science (ASIPP).
A prototype single driver ion source with dimension of 200mm was developed and tested on the test facility to pre research the key technology of RF plasma generator. The driver equipped with a water-cooled Faraday shield to protect the alumina cylinder from the plasma and the plasma expands into the rectangular expansion chamber. The RF power of 50 kW with frequency of 1MHz is transferred to the RF driver by a matching unit. The characteristics of plasma discharge were studied with classical diagnostic tools, such as Langmuir probe, optical emission spectroscopy (OES) and water-flow calorimetry (WFC). Based on the plasma performance tests, high power of 50 kW plasma discharge with long pulse of 1000s was achieved. In this paper, the detail design of ion source, characteristics of plasma and future research plan will be presented.
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