U.S. Particle Accelerator School

Fourth Generation Light Sources II : ERLs and Thomson Scattering course

Sponsoring University:

Indiana University


Fourth Generation Light Sources II : ERLs and Thomson Scattering


Geoffrey Kraft, TJNAF and Ivan Bazarov, Cornell University

The next generation of synchrotron light sources may not be (only) an x-ray laser. Other ideas are presently under intense study to generate high-performance x-ray beams for applications in applied and basic sciences. The Energy Recovery Linac (ERL) tries to combine the desirable features of a linac beam - for example femtosecond bunches - with those of a storage ring to achieve femtosecond x-ray pulses. On a smaller scale, and therefore faster track, is the application of Thomson scattering to achieve femtosecond x-ray pulses. This course will give an introduction into the physics and technologies involved with the accelerator-based femtosecond x-ray sources.

The first part of this double course on Fourth Generation Light Sources concentrated on the production of X-rays from linac based Free Electron Lasers through the self-amplified spontaneous emission (SASE) process. Several other and complementary processes are under intense study to produce X-rays, specifically, accelerator based femtosecond X-ray pulses. Such pulses are of great interest in Chemistry and Biology to understand the dynamics of complex chemical processes, which occur on a time scale of less than a picosecond. Short-pulse X-rays may be produced by the use of incoherent emission processes already well known and studied in storage rings, in accelerating devices that are specially designed for the task. This course will present a unified description of existing and proposed short pulse sources: from Thompson/Compton scatter sources based on scattering laser light from relatively low energy electron beams, to higher energy, high average current energy recovery linacs, ERLs, recently garnering interest as the next development beyond present day storage rings light sources. These more recent developments provide challenging and demanding physical and technical problems and broad opportunities for creative ideas. Prerequisites: It will be assumed that students know the basics of relativity theory, classical electrodynamics and statistical mechanics. Previous courses in general Accelerator Physics and in Collective Effects and Beam Instabilities are strongly recommended.