Development of Multi-pulse Compact Toroid Injector System for C-2U

The C-2U [1] experiment aims at sustaining a dynamically formed field reversed configuration (FRC) for 5$+$ ms via injection of 10$+$MW of neutral beams. One of the systems currently used to refuel the C-2U plasma is a single pulse compact toroid injector (CTI) [2]. The CTI is a magnetized co-axial plasma gun, which generates a spheromak-like plasma that is injected into the core of the advanced beam-driven FRC of C-2U. In order to refuel the recent long-lived plasmas in C-2U, a multi-pulse CTI system, whose modular design allows for expandable burst numbers, is being designed. Details of the pulsed power systems used to energize the single pulse and the upgraded multi-pulse CTI will be discussed. Results of injector performance carried out on a dedicated test stand as well as some refueling data on C-2U will also be presented. \\[4pt] [1] M. Binderbauer et al., Physics of Plasmas, 22, 056110 (2015)\\[0pt] [2] T. Matsumoto et al., Bull. Am. Phys. Soc. 59, UP8.00008 (2014)