Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have\nremained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication,\nremain central to almost all X-ray applications, there have been few fundamental technological advances. However, with\nthe emergence of ever more demanding medical and inspection techniques, including computed tomography\nand tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a\nconsiderable level of interest in the development of new fabrication methods. The use of conventional thermionic\nsources is limited by their slow temporal response and large physical size. In response, field electron emission has\nemerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined\ndistribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such\nsystems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in\ncarbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional\nadvantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped\ncathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of\nsome of the commercial progress made towards the realisation of an innovative and disruptive technology
Loading....