Field emission studies on technical niobium surfaces

The performance of superconducting accelerating cavities are limited by the spurious field emission of electrons. Various vacuum surface treatments have been investigated in a UHV system to reduce this emission. On baked niobium samples, the application of an electrical field leads to a gradual decrease of the field emitted currents; after treatment in an argon glow discharge, the currents are high and stable. An argon/oxygen discharge reduces markedly the field-emitted currents and could be an interesting treatment for superconducting cavities.<
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