Neutral Beam Injection system with tunable beam energy for the C-2W experiment

Reproducible beam-driven Field-Reversed Configurations (FRCs), sustained by tangential neutral beam injection for times significantly longer than characteristic plasma decay times, have been demonstrated with steady magnetic fields in the C-2U experiment [1]. In order to demonstrate FRC ramp-up, the C-2W experimental device has been designed, built and commissioned.  It is equipped with a set of eight neutral beam injectors (NBI’s). Four out of the eight NBIs have a capability whereby the beam energy can be tuned during a shot from the initial 15 keV up to 40 keV at a constant beam current. Tunable beam energy allows optimization of the beam-plasma coupling during ramp-up of the magnetic field in the confinement section. This presentation provides an overview of the NBI system with tunable beam energy, including its design, layout of the power supply system, and initial operation results.

[1] M.W. Binderbauer et al., AIP Conf. Proc. 1721, 030003 (2016)