What is missed here is a potential military application. Since most of the neutrons are generated along the axis of a dpf device, esp. from d-t fusion, it could be used as a satellite killer. Building in enough shielding to protect electronics from a serious flux of high energy neutrons is very expensive, and if such a space weapon were demonstrated, a satellite proliferation race would result to counter it. Of course, blasting satellites to pieces also fills the sky with junk.
