Microwave Linear Accelerators

David Whittum, Varian Medical Systems and Eric Colby, Stanford Linear Accelerator Center

 

Purpose and Audience

This course will introduce microwave linear accelerators starting from Maxwell’s equations and the Lorentz force law. Students are typically senior undergraduates or graduate students in physics, applied physics, or electrical engineering. Auditors have included accelerator systems operators and technicians, mechanical and manufacturing engineers. Auditors should be completely comfortable with algebra, trigonometry, capacitance,  inductance and description of oscillatory motion via a 2nd order differential equation. Students who have had a course in intermediate electromagnetics should enroll for a grade.

 

Objectives

Students will learn how to describe the behavior of an accelerator in the time or frequency domain, and to explain the theory behind cold-test measurements, and observations with beam. They will use CAD tools to design a structure including the input coupler. They will become familiar with the practical design trade-offs and the manufacturing and operational aspects of normal conducting microwave accelerators. They will be able to analyze their accelerator application and describe it in conventional terms.

 

Instructional Method

There are two lectures each morning with a 20-minute break in between. After lunch there will be a computer lab, with a goal of one computer per student. After another 20-minute break there will be a homework review session or a special topic lecture. An important resource for this course is the (optional) evening homework and study session, where students usually work together on problems. Instructors will come by a couple of times during the evening to help with homeworks if needed. All homeworks and exams are open book, and collaboration is encouraged except for the final exam, where the honor system is in force.

 

Course Content

Structure modelling and design are developed from an elementary point of view, with CAD lab exercises for illustration.  Topics include quality factor, [R/Q], shunt impedance, loss factor, VSWR, Slater's theorem, external coupling, cell-to-cell coupling, Brillouin curve, tuning errors, tuning, tolerances, field-symmetry. The behavior of standing-wave and travelling-wave structures is analyzed on and off resonance, in cold test, and in operation with beam loading. Additional topics influencing linac design will be selected based on student interest and may include  rf systems, instrumentation, beam dynamics, wakefields. It is important for students to fill out the course questionnaire available on the web to express their particular interests and applications. Illustrations and exercises will be drawn from practical problems in industrial, medical and high energy physics applications.

 

Reading Requirements

References may be found at the course URL. Reading will consist of two sets of notes that will be distributed to enrolled students beforehand: Introduction to Electrodynamics for Microwave Linear Accelerators (slac-pub-7802) and  Introduction to Microwave Linacs (slac-pub-8026). The first chapter of  slac-pub-7802 should be read before the course. Lectures will proceed more along the intuitive lines of slac-pub-8026, albeit with mathematical forays as needed in the style of slac-pub-7802. The detailed lecture schedule is available at the course URL.

 

Credit Requirements

Credit is based on exercises given in seven homeworks, one midterm, and one final exam. Each part of each exercise carries a weight of at least one point, and more difficult exercises will carry up to 4 points. Points for the course usually total about 150, with typically 20 points each for midterm and final. Extra credit opportunities will appear frequently.

see also: http://home.earthlink.net/~whittum/vu/