The vaporisation behaviour of americium dioxide by use of mass spectrometry

The vaporisation behaviour of americium dioxide in vacuum at high temperatures up to 2400 K has been studied. A Knudsen cell coupled with a mass spectrometer was used to perform vapour pressure measurements. The ionisation efficiency curves of Am+, AmO+ and AmO2+ were simultaneously recorded. Appearance potentials of the key molecular species were determined by varying the energy of the ionising electrons at constant temperature. The partial and total vapour pressures above the americium oxide samples measured as a function of the temperature. The results on the vapour pressure of the pure americium dioxide samples were discussed together with the available literature data on plutonium dioxide containing small amounts of americium. Additional measurements have been performed on a mixed dioxide sample of plutonium containing 6.1 wt.% americium.