Development of Diamond Field-Emitter Arrays for Free-Electron Lasers

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DFEAs can be conditioned for highly-uniform emission: Investigated several conditioning methods: 1. Selective gas exposure • no improvement thus far 2. Vacuum Thermal Electric Conditioning (VTEC) • High field annealing of tightly adsorbed species • Greatly improved temporal stability 3. Sustained moderate/high current operation • Morphology changes by thermal-assisted field evaporation CVD diamond cathode Quartz capillary Glass/Y 2 O 3 :Eu/Ni (5nm) + HV A Mo substrate
High current conditioning most successful thus far: • Evaporation of nanotips is self limiting, leading to highly uniform emission. • Similar to pulsed conditioning of Spindt cathodes. • During conditioning studies, microtips achieved per-tip currents exceeding 15µA. Scales to 100A/cm 2 DC for highest densities • Studies limited by anode destruction (a) (b) (c) (d) (e) (a) (b) (c) (d) (e) unconditioned After 0.5hr at ~20nA/tip After 0.5hr at ~100nA/tip After 0.5hr at ~500nA/tip After 1hr at ~ 1.5µΑ/tip ~200°C VTEC
Page 1 and 2: Jonathan D. Jarvis, Heather L. Andr
Page 3 and 4: DFEAs have several advantages over
Page 5: DFEAs are fabricated by a mold-tran
Page 9 and 10: Measured emittance agrees well with
Page 11 and 12: Estimated resolution is better than
Page 13: Conclusions: • DFEAs are very rug

Development of Diamond Field-Emitter Arrays for Free-Electron Lasers

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