U.S. Particle Accelerator School

Linear Accelerator Design for Free Electron Lasers course

Sponsoring University:

Rutgers University


Linear Accelerator Design for Free Electron Lasers


Simone Di Mitri, Elettra-Sincrotrone Trieste; Marco Venturini, Lawrence Berkeley National Laboratory

Purpose and Audience
This course will provide the fundamentals of linear accelerator (LINAC) design in applications to Vacuum Ultra-Violet (VUV) and X-ray Free Electron Lasers (FELs). The course is intended to cover primarily single-pass systems; recirculating LINACs will be treated briefly if time permits. The course will include computer sessions and will be taught at a level suitable for graduate students, post-graduate students and post-doctoral fellows.

Knowledge of classical mechanics, electrodynamics, and special relativity at the level of first-year graduate or advanced undergraduate school. Grasp of basic notions of accelerator physics (radio-frequency acceleration, magnetic focusing, beam optical parameters, transfer maps) is recommended. Familiarity with specialized topics (e.g. synchrotron radiation, FEL physics, photo-cathode injectors, electron beam diagnostics) is useful but is not required.

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

The emergence of FELs as radiation sources of unprecedented brilliance and coherence properties in the VUV and X-ray spectrum has been one of the most recognizable trends of the last decade. Some of these light sources have already come to line, others are under construction, and more are expected in the near future. The goal of the course is to present the challenges that have to be met by the LINAC drivers for these light sources; show how the FEL requirements and practical constraints affect the machine design, and guide the students into the process of designing a machine that meets those requirements. The FEL performance is strictly dependent on electron beam quality. As the LINAC design plays a crucial role in preserving beam quality as well as performing the beam manipulations required to enable the machine performance, various issues of single-particle and collective effect beam dynamics will be emphasized. Whenever possible we will use real-life examples to illustrate concepts, lattice, and machine design solutions.

Instructional Method
The course will consist of approximately 20 hours of lectures. In addition, there will be approximately 8 hours of computer labs intended to introduce the use of software tools for machine design and optimization, demonstrate concepts presented in the lectures, and perform particle tracking. Homework assignments for the evening will help the student to review and master the basic concepts introduced in class.

Course Content
The course will cover several aspects of the LINAC design for FELs, starting with the choice of the fundamental beam and machine parameters needed to meet the FELs performance specifications. We will discuss the acceleration requirements and basic technology options to achieve the desired beam energy and repetition rates. We will treat the relevant longitudinal and transverse aspects of beam dynamics (including single-particle and collective effects), and discuss in detail the special insertions needed for beam manipulations: magnetic compressors and higher frequency accelerating cavities primarily, laser heater, collimation systems and diagnostic insertions if time permits. We will present lattice design strategies to optimize beam transport while preserving the transverse and the longitudinal emittance. Aspects of photo-cathode injector and FEL physics that may inform the LINAC design will be recalled briefly but the students are encouraged to refer to dedicated USPAS courses on those subjects for more in-depth coverage. In the computer classes the students will learn to use established tracking codes to build a simplified machine model, study the beam dynamics through various sub-systems, and verify the impact of various LINAC design choices.

Reading Requirements
(to be provided by the USPAS) "Particle Accelerator Physics" - third edition (Springer 2007) by Helmut Wiedemann.
Instructor-provided course notes will also be distributed.
Recommended Reading: “Fifth General Accelerator Physics Course”, CERN 94-01, Vol. I (1994) (free download at http://cds.cern.ch/record/235242/files/).

Credit Requirements:
Students will be evaluated based on performance as follows: final exam (40% of final grade), homework assignments (30%) and computer class (30%).

Rutgers University course number 01:750:648 Linear Accelerator Design for Free Electron Lasers

IU/USPAS course number P671