A field emission (FE) cathode for a vacuum electronic device (VED) includes a graphite substrate or framework in the shape of a hollow cylinder, and at least one continuous carbon nanotube (CNT) fiber in tension or compression around at least a portion of the graphite substrate. The at least one continuous CNT fiber can include a filament, yarn, braided yarn, film, fabric, or combination thereof. The at least one continuous CNT fiber is secured to the electrically conductive substrate by vacuum brazing or any other suitable means.