U.S. Particle Accelerator School

Cathode Physics course

Sponsoring University:

University of Texas at Austin


Cathode Physics


John Smedley, Brookhaven National Lab and Matt Poelker, Jefferson Lab

Purpose and Audience
From x-ray free-electron lasers, to high-average-current Energy Recovery Linacs, to polarized electron sources for future colliders, accelerator physics begins at the cathode. This course is designed for graduate students in physics and materials science interested in understanding the fabrication, optimization and application of electron sources to accelerators, primarily photoemission sources that produce beams with small emittance.


Undergraduate mechanics and electricity/magnetism. Some familiarity with quantum mechanics and solid-state physics is desirable but not mandatory.

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

To introduce students to electron sources used at modern accelerators and to provide the basic understanding why one type of source is chosen over another. To describe the physics of electron emission from materials, and some of the technological challenges associated with different electron-emission mechanisms.

Instructional Method
This course includes a series of 8 lectures, a computer session and a presentation period.

Course Content
This course will provide an overview of the various cathode technologies used at accelerators, focusing primarily on photocathodes, but also including thermionic and field-emission sources. Issues related to the operation of cathodes in RF, SRF and DC guns will be covered, along with methods of choosing the optimum electron source for a given application. The theory of photoemission will be outlined, along with an overview of laser technology for photocathodes. To introduce modern materials science techniques, such as x-ray diffraction (XRD) and photoemission spectroscopy (UPS/XPS), which are relevant to the study of photocathodes.

Reading Requirements
(to be provided by the USPAS) Handouts. A textbook may be added at a later date.

Credit Requirements
Students will be evaluated based on performance on homework assignments and a presentation.

Students will be evaluated based on the following performances: homework assignments (50%) and final presentation (50%).

IU/USPAS course: Physics 671