Speaker
Description
We are presenting the simulation results of the hot tungsten filament behavior in a Freeman ions source installed in the LANL electro-magnetic isotope separator (EMIS). The Freeman source enables us to ionize and extract high intensity single-charge ion beams from different gases as well as from various solid materials in order to purify the content of a selected isotope [1].
We have modified and adopted the LANSCE H$^{-}$ Ion Source Filament Model [2] to calculate the ion source working parameters during a beam production cycle and estimate the ion source filament lifetime. Two main mass erosion processes of the hot cathode in a Freeman ion source are included: thermal evaporation and plasma sputtering. The working temperature of source filament was estimated to be in range of 2400 to 2500 K. The filament model shows that the plasma sputtering rate is several magnitude of order higher than the thermal evaporation rate.
The results of ion source modeling were compared with recorded data (LABVIEW) taken during two EMIS beam production runs using krypton noble gas.
References
[1] D. J. Chivers, “Freeman Ions Source: An overview” Rev. Sci. Instrum. 63, 2501 (1992).
[2] I. N. Draganic, J. F. O’Hara and L. J. Rybarcyk, “Different Approaches to Modeling the LANSCE H$^{-}$ Ion Source Filament Performance” Rev. Sci. Instrum. 87, 02B112 (2016).
