University of Maryland
Bruce Carlsten and Steven Russell, Los Alamos National Lab
Purpose and Audience
This course will provide a solid foundation for understanding how common microwave devices work, particularly those associated with driving accelerators. The course will be taught at a level suitable for a first-year graduate student.
A course in Electromagnetism and Calculus.
After the course, the student will understand the basic operating principles of common standing wave (klystron) and traveling-wave (TWT and FEL) microwave devices, particularly how electron beams exchange energy with rf fields. In principle, the student will be able to predict device gain and efficiency, and will understand basic beam dynamics and focusing in microwave tubes, as well as both longitudinal and transverse space-charge effects.
The course will consist of 25 hours of lectures during the morning and afternoon, focusing on the theoretical understanding of the course content, and will be complemented by afternoon 2-hour sessions in the computer lab in which students will have an opportunity to numerically simulate klystron performance. Daily homework will be given that lets the student review basic concepts introduced in class.
Three general topics will be covered - (1) beam physics important for microwave tubes, (2) standing-wave amplifiers, and (3) traveling-wave amplifiers. The beam physics material will include topics on magnetic focusing and space-charge forces, such as Busch's Theorem, solenoidal and PPM focusing, diamagnetic effects, potential depression, space-charge waves, balanced flow, confined flow, and Brillioun flow. A detailed analysis of how a klystron works will be used as an example of a standing-wave amplifier. A beam/cavity interaction model based on induced current will be presented. Students will have an opportunity to understand and use a simplified klystron simulation code (which neglects space-charge effects) in the computer lab. A Pierce-type traveling-wave tube analysis will also be presented, which will be used to describe a common helix traveling-wave tube and a free-electron laser. Selected unconventional sources and non accelerator applications will be surveyed.
Students will be evaluated based on performance: homework 30% of final grade, final exam 30% of final grade, and computer lab project 40% of final grade.