New capabilities and upgrade path for the DIII-D neutral beam heating system

•The DIII-D neutral beam system continues to evolve to provide new capabilities.•Internal beamline components are being upgraded for higher power, longer pulse.•One beamline being rebuilt to provide off-axis co- or counter-injection.•New low voltage capability and more versatile controls being developed.•MACE device built to investigate ion source operational issues in helium. As physics experiments on the DIII-D tokamak evolve to explore new regimes in fusion energy research, the capabilities of the Neutral Beam Injection (NBI) systems are being improved to help provide the necessary tools. Upgrades of beamline internal components and high voltage systems are currently being carried out to increase the injected power and pulse length. A new algorithm has been commissioned for feedback control that combines the variable beam energy (VBE) and variable beam perveance (VBP) capabilities. An extensive project is underway to modify a beamline for off-axis injection in either the co- or counter-plasma current direction. The MACE device (Miniature Arc Chamber Experiment) has recently been commissioned and is allowing investigation into the detrimental effects of operating ion sources in helium. Finally, exploration of the edge physics in tokamaks has benefited from a new capability to inject very low energy beams (15–20 kV). A description of these new capabilities and some results from experiments will be presented here.