Extraction of a negative hydrogen ion beam from a microwave ion source

• Published in: Fusion engineering and design Vol. 26; no. 1; pp. 495 - 500
• Main Authors: Hashimoto, Kiyoshi, Asano, Shiro
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1995
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/0920-3796(94)00216-T

A microwave ion source has been developed for negative-ion-based neutral beam injection. The plasma generator of the test source is a 15 cm diameter, 16.5 cm long cylindrical chamber. Two ring-shaped permanent magnets are set around the chamber. The microwave power (2.45 GHz) is introduced into the chamber through a ceramic window and a rectangular waveguide, which are biased positively with reference to the chamber. The reflection power of the microwave is reduced effectively by biasing the waveguide and the window. A negative hydrogen ion beam with a current density of 3.4 mA cm −2 was extracted steadily at an operating pressure of 0.3 Pa without cesium seeding, with a net microwave power introduced into the chamber of 2.8 kW.