用于交叉碰撞实验的金属毛细管式中性原子源

Metallic capillary atom source for cross beam collision study

基于金属材料的加热蒸发机制,在钽舟的基础上设计了一套结构简易的中性原子源。该原子源的源仓和加热体均采用金属毛细管形式,保证了原子源具有耗能小、加热温度高的特点;提供的中性原子流具有发散度小、密度大、稳定性好的优点。采用加热蒸发铥样品的方法对其性能做了详细的检验,结果它在低耗能的情况下,温度能够顺利升高到2 600 K;可以连续8 h提供强度为8.5×1016/s的中性Tm原子流,且束流的稳定性好于±5%。充分证实了该套原子源应用于电子、离子和光子与中性原子流交叉碰撞实验的可靠性。

A metallic capillary atom beam source of simple and compact design is described. As the first test, thulium is evaporated and the cations which are mainly due to the thermal ionization are measured. The strongpoint of small power and high temperature of atom sourceis proved by temperature approaching 2 300 K corresponding to only 180 W power. The stability of thulium atom beam for two hours is better than 5 %. An atom beam density of about 8×10^-12cm^-3 in the region at a distance 35 mm beyond the source exit is easily attained and can be sustained for about 8 hours. The test has testified that the metallic capillary atom beam source is suitable for crossed beam study of collision processes involving electrons, ions or photons where the colli- sion products may be studied by methods based on mass spectrometry or optical spectroscopy.