Experimental evidence of improved confinement in a high-beta field-reversed configuration plasma by neutral beam injection

Abstract

The first experimental result of high power (14 kV, 23 A) neutral beam (NB) injection into a high-beta field-reversed configuration (FRC) is demonstrated. The result makes it clear that the NB injection improves the plasma performance, increasing the configuration lifetime more than 200% in comparison with the ordinary FRC under similar conditions. A novel NB injection system is presented for application to FRC plasmas. A set of three concave electrodes for beam extraction is used to focus the beam enabling to pass through a narrow port. The target of beam injection is a large bore FRC plasma contained in a mirror field with a mirror ratio of 2–9.