Oscillator-Amplifier Free Electron Lasers an Outlook to Their Feasibility and Performances

<p>This reprint is aimed at presenting strategic and design elements for the development of low-cost low-size Free Electron Lasers.</p><p>Different points of view are considered here attempting to consider technologies and design conceptions that are fairly mature and may be viable solutions in the near or midterm future.</p><p>The design conceptions proposed here are based on the so-called hybrid (or broader-approach) technologies which put together e.g. combinations of oscillator and amplifier configurations.</p><p>These solutions although developed almost thirty years ago appear nowadays within the present technological capabilities.</p><p>Other possibilities offered for example by the recirculated wave undulator FELs represent border line technologies which are worth carefully studying as the architecture of the mid-term future. Finally the reprint addresses both theoretical and design considerations regarding proposals for the enhancement of coherent emission on higher harmonics.</p>