Effect of surface roughness of high current density nano-particle cathode for terahertz vacuum devices application

High current density dispenser cathode is critical need for used in high power terahertz devices. Recently scandate cathode using nanoparticle offers very high current density more than 100 A/cm2. Fabrication of this kind of cathode is challenging issue due to its nano dimension of the particle size. One of the critical parameter is surface roughness of the emission surface. We develop dispenser cathode using tungsten nano-particle of average particle diameter ∼50 nm, spherical morphology and uniform phase. In this paper we explain the effect of surface roughness on the emission current density of the dispenser cathode.