The term light source is used to describe the collection of photon-generating devices. This chapter examines photon light sources and focuses on synchrotron radiation sources, free-electron lasers (FELs), and selected photon-generating approaches including Compton backscatter, laser ion acceleration (LIA), wake-field acceleration, laser accelerators, X-ray induced isomeric transitions, and gamma-ray lasers (GRA-SERs). The application of these devices is expected to enter a number of new areas in the twenty-first century.
Light source applications continue to expand as the brightness and range of wavelengths increase. These applications occur in a wide array of fields including biology, chemistry, condensed matter physics, geology, material science, medicine, and solid-state physics. Light sources probe the structure of matter over a broad frequency range. Specific applications of light sources include the research and development of pharmaceuticals, computer chips, motor oils, new materials, and manufacturing techniques. Given the range of practical applications, light source use and application will expand and require additional health physics attention as the twenty-first century progresses.
Both synchrotron light sources and free-electron lasers are based on the concept that an accelerated charge radiates photons. The output from these photon sources is quite intense and presents an external radiation hazard that must be carefully managed.
This chapter examines the nature of radiation from synchrotron light sources, freeelectron lasers, and other photon-generating approaches and addresses their health physics implications. Prior to reviewing these sources of radiation, the concepts of bremsstrahlung and synchrotron radiation, and the physics underlying these radiation processes are addressed.