U.S. Particle Accelerator School

>RF Cavity and Component Design for Accelerators course

Sponsoring University:

University of Tennessee, Knoxville


RF Cavity and Component Design for Accelerators


Alireza Nassiri and Geoff Waldschmidt, Argonne National Laboratory

Purpose and Audience
The purpose of this course is to introduce the students to the design and modeling of rf cavities and components for accelerators. This course is suitable for senior and/or first year graduate students from the fields of physics, applied physics, and electrical engineering who are considering an accelerator physics or engineering career. This course provides an essential background and hands-on rf and microwave modeling for accelerator design.

Upper division undergraduate courses in electromagnetism (at the level of “Introduction to Electrodynamics” by David J. Griffiths), integral calculus, and differential equations (at the level of “Advanced Calculus” by Gerald B. Folland).

It is the responsibility of the student to ensure that he or she meets the course prerequisites or has equivalent experience.

The objectives of this course are: 1) to review fundamental rf and microwave engineering principles, 2) apply these principles to the design and analysis of rf cavities and components for accelerator applications, 3) learn and become proficient in numerical modeling and rf simulation, and 4) use modeling and simulation tools to design and analyze realistic rf components for accelerators. The students will also be exposed to limited hands-on rf measurement techniques and beam-cavity interaction topics. Upon completion of this course, students are expected to understand fundamental rf and microwave principles and to successfully design, model, and analyze accelerator components.

Instructional Method
This course combines lectures, computer laboratory, and (limited) hands-on rf measurements to accomplish its objectives. This includes a series of twenty lectures during morning sessions, followed by afternoon computer laboratory and rf measurements using a network analyzer. The purpose of the lectures is to teach students fundamental concepts through mathematical treatment and to apply these principles to numerical design and modeling and rf measurement of rf components. The instructors will help students get familiar with Microwave Studio - a popular electromagnetic simulation tool which incorporates fundamental beam interaction. This will be accomplished through interactive and hands-on activities. Ample examples will be provided to help students to develop their computer skills. For the computer laboratory sessions, students initially work in small groups and, as they gain experience and expertise, they will work on their own. In addition, the students will have an opportunity to use network analyzer (NWA) techniques to measure and characterize rf properties of a limited number of rf components. Students are expected to complete a set of laboratory assignments and rf measurements in addition to problem sets from the morning lectures. Students are expected to choose and complete a final design project assignment.

Course Content
Review of basic rf and microwave theory and properties, transmission lines, Smith chart, impedance matching, field analysis of transmission lines, waveguides, accelerating cavities, power couplers, and other resonant structures. Computer laboratory sessions will focus on understanding and using the design and simulation code Microwave Studio. Rf cavity measurements will be performed using NWA techniques. Fundamental topics will include Maxwell’s equations, Green’s functions, boundary conditions, wave propagation and plane waves, plane wave reflection from a media interface, and dielectric interface. Course topics will include transmission line theory, wave propagation, field analysis in resonant structures, generator and load mismatches, microwave network analysis, microwave resonators, physics of microwave tubes, dielectric and other lossy materials, time harmonic analysis, perturbation and variational techniques, microwave measurements, impedance, and noise factor. Acceleration by rf systems for linear accelerators and storage rings including beam / cavity interaction, beam-loading, higher-order mode (HOM) effects and mode damping will be explored. Numerical methods, including finite difference time domain, finite element, stability conditions, and absorbing boundary conditions will be discussed.

Reading Requirements
(to be provided by the USPAS) “Microwave Engineering,” Wiley (2012), 4th edition by David M. Pozar. Additional suggested reference not provided by the USPAS: R.E. Collin, “Foundation of Microwave Engineering,” McGraw-Hill 1994. Additional reading materials will be provided by the instructors.

Credit Requirements
Students will be evaluated based on performance: final exam (30% of final grade), computer lab assignments and rf measurement (35% of final grade), and homework assignments (35% of final grade).

IU/USPAS course number P571