A large-area planar helicon plasma source with a multi-ring antenna on Linear Experimental Advanced Device (LEAD)

A planar helicon plasma source with a four-ring antenna has been developed on Linear Experimental Advanced Device (LEAD) in Southwestern Institute of Physics. The diameter of the largest antenna ring is 320 mm. This source is located outside of the vacuum chamber without any vacuum interface and injects radio frequency power into the chamber through a 340-mm-diameter quartz window. A low power threshold of 150 W for electromagnetic-mode to wave-mode transfer is experimentally confirmed. A large volume plasma with a density of over 1019 m−3 and a plasma generation efficiency (total number of electrons diveded by input power) of over 30× 1013 W−1 indicate the high performance of this large-area helicon plasma source, promising LEAD a suitable device for fundamental plasma physics and plasma material interaction research.