Alkali metal source tablet for vapor cells of atomic magnetometers

An array system of optically pumped atomic magnetometers (OPAMs) that uses potassium vapor cells requires the quantity of potassium enclosed in the cells to be uniform. We describe a tablet-shaped potassium source, which generates a fixed amount of potassium, for fabricating homogeneous vapor cells. The tablet consists of a tiny microstructured plate covered with a layer of raw materials. Two sets of raw materials were chosen: one was a mixture of KCl and BaN₆, and the other was KN₃. The efficiency of potassium generation depended on the shape and size of the microstructure for each raw material, and a maximum potassium yield of 65% was observed for KN₃ tablets. The source tablets containing KCl and BaN₆ were used to build vapor cells by a microfabrication technique, and the source tablets containing KN₃ were used to introduce potassium into glass cells, which were confirmed to work in highly sensitive OPAMs.