  Compact and robust ion traps for thorium are enabling technology for the next
generation of atomic clocks based on a low-energy isomeric transition in the
thorium-229 nucleus. We aim at a laser ablation loading of single triply
ionized thorium in a radio-frequency electromagnetic linear Paul trap.
Detection of ions is based on a modified mass spectrometer and a channeltron
with single-ion sensitivity. In this study, we successfully created and
detected 232Th+ and 232Th2+ ions from plasma plumes, studied their yield
evolution, and compared the loading to a quadrupole ion trap with Yb. We
explore the feasibility of laser ablation loading for future low-cost 229Th3+
trapping. The thorium ablation yield shows a strong depletion, suggesting that
we have ablated oxide layers from the surface and the ions were a result of the
plasma plume evolution and collisions. Our results are in good agreement with
similar experiments for other elements and their oxides.
