Microwave Sources

Sponsoring University:

Northern Illiniois University

Course Name:

Microwave Sources
This class is limited to 20 students

Instructors:

Bruce Carlsten, Steven Russell, Haoran Xu and Kip Bishofberger, Los Alamos National Lab

Purpose and Audience
This graduate-level 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.  The course will be of interest to graduate students, scientists and engineers interested in microwave sources for accelerator applications.

Prerequisites
Undergraduate level Mechanics with Special Relativity and Electromagnetism are required. Familiarity with accelerator physics at the level of the USPAS course "Fundamentals of Accelerator Physics and Technology with Simulations and Measurements Lab" is required.

It is the responsibility of the student to ensure that they meet the course prerequisites or have equivalent experience.

Objectives
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.  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.

Instructional Method
The course will consist of 45 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 using the community-standard klystron modeling code AJDisk.  Daily homework will be given that lets the student review basic concepts introduced in class.  Instructors will be available during evening homework sessions.

Course Content
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 permanent magnet 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 1-dimensional klystron simulation code in the computer lab.  A Pierce-type traveling-wave 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. 

Reading Requirements
(to be provided by the USPAS) “Klystrons, Traveling Wave Tubes, Magnetrons, Cross-Field Amplifiers, and Gyrotrons” by A. S. Gilmour Jr. (Artech House, 2011) and instructor-provided handouts.   

Credit Requirements
Students final grade will be evaluated based on performance: homework 30%, in-class in-class final exam 30%, and computer lab project 40%.

USPAS Computer Requirements
There will be no Computer Lab and all participants are required to bring their own portable computer to access online course notes and computer resources. This can be a laptop or a tablet with a sufficiently large screen and keyboard. Windows, Mac, and Linux-based systems that are wifi capable and have a standard web browser and mouse are all acceptable. You should have privileges for software installs. If you are unable to bring a computer, please contact uspas@fnal.gov ASAP to request a laptop loan. Very limited IT support and spare loaner laptops will be available during the session.

Northern Illinois University course number: PHYS 790D Special Topics in Physics - Beam Physics
Indiana University course number: Physics 571, Special Topics in Physics of Beams
Michigan State University course number: PHY 963, "U.S. Particle Accelerator School"
MIT course number: 8.790, Accelerator Physics