{'fraction_non_alphanumeric': 0.018537590113285273, 'fraction_numerical': 0.012358393408856848, 'mean_word_length': 5.075, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

Advances in superconducting linac technology offer the possibility of an upgrade of the Jefferson Lab Free Electron Laser (JLab FEL) facility to an oscillator-based VUV-FEL that would produce 6 × 1012 coherent 100 eV photons per pulse at multi-MHz repetition rates in the fundamental. In this paper we present novel designs that are verified by model calculations which have themselves been validated by comparison with experimental performance measurements using oscillator-based continuous-wave free electron lasers (FELs) operating in the IR and UV, with sub-picosecond pulses up to 75 MHz and producing harmonics upwards of 10 eV. The accelerator uses an energy recovered linac design for efficiency of operation, and high gain per pass in the oscillator. The fully coherent nature of the source results in peak and average brightness values that are several orders of magnitude higher than storage rings.