A new atomic beam source: The “candlestick”

The design of a novel-type of atomic beam source which provides for long term, stable operation at high emission rates is reported. The heart of the design is the “candlestick” where liquid source material is transported by capillary action to a localized hot emission region. A surrounding cavity kept at the melting point for the source material shields the vacuum chamber walls from this region. The atomic beam escaping from the source is collimated, and uncollimated atoms are transported back to the liquid reservoir at the bottom of the “candlestick” by capillary action. This design has advantages over traditional oven designs: localized heating provides for large emission rates under high vacuum conditions, collimation is combined with recycling and conservation of source material, and the use of capillarity allows any orientation of the beam source. The source has been tested with sodium, and we believe that the design is useful for a broad range of applications including thin-film evaporation, molecular beam epitaxy, and semiconductor surface doping. With the low thermal mass of the emission section, the source could be optimized for pulsed mode operation. Furthermore, it is anticipated that the design ideas presented here could form the basis for a supersonic source with very high Mach numbers. 8 1994 American Institute of Physics.