100s Pulse of Neutral Beam Extracted on EAST-NBI

Recently, there was a new significant progress on the neutral beam injector of EAST auxiliary heating project (EAST-NBI), which is funded by the National Development and Reform Commission, in the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP).The hydrogen neutral beam in long pulse of 100 seconds was extracted on the EAST-NBI test bed, which verifies the ability of long pulse operating of the EAST-NBI preliminarily. The long pulse neutral beam was the first extracted in China, which indicates a new milestone in the development of neutral beam injection auxiliary heating project.

EAST-NBI system was completely and independently developed by China. The system involves many fields, such as current ion source, high vacuum, cryogenic engineering, high voltage and isolation technology, remote measurement and control, plasma and beam diagnosis. During the test, 9A beam current with 50keV beam energy was achieved. The beam pulse was up to 100s, and the ion beam power was about 0.3 MW. The test succeeds in examining the performance of mega-watt high current ion source. It demonstrates that all the sub-systems of EAST-NBI are capable of supporting long pulse of 100s. Moreover, it shows that the EAST-NBI project has achieved on schedule its milestone objective – development of the first long pulse high current ion source and experimental equipment.

The extraction of higher beam power in 100s pulse length will be tested and verified on EAST, considering the limits of the NBI test bed. The results, as an important milestone, marks the overcoming of the major technical difficulty. The success lays a sound foundation for the application of NBI in EAST experiments in 2013. (Liu Zhimin reports)