Based on the image of the machine, this is a magnetic mirror with neutral beam injection. Mirrors were some of the first plasma confinement devices. An issue they have is that they lose charged particles out the ends in a way that depends on the ratio of perpendicular to parallel velocity and the magnetic field strength. It may be that they think they can use the neutral beam injectors to inject the fuel in such a way that it's well confined in the machine...

Never mind, another linked article says that the injectors are only used for ignition.