Comprehensive secondary electron emission modeling for simulating e-beam collection in MICHELLE

Summary form only given. Electron beam collection systems variously employed in O-type fast-wave and slow-wave devices such as gyrotrons, gyroklystrons, klystrons, and TWTs must often be carefully designed to avoid potentially undesirable consequences of secondary electron production at the electrode surface(s). An advanced, three-dimensional electron beam design tool, called MICHELLE, is currently undergoing development by a team lead by SAIC under ONR sponsorship. As part of this new effort, an algorithmic representation of a comprehensive model of secondary emission is being developed for this computational tool in order to achieve an accurate beam collection design capability. The secondary emission model separates the emission problem into two macroparticle species: (1) true secondary electrons (SSE) and (2) rediffused (or backscattered) primary electrons (BSE). Each emitted particle species is assigned empirically-based, discrete angular and energy distributions in normalized form, which in turn are dependent upon both the incident particle energy and angle of incidence. Also, provisions for material-specific surface roughness contributions are included in approximate fashion. Algorithms used to capture the secondary emission model will be detailed.