Loading of large ion Coulomb crystals into a linear Paul trap incorporating an optical cavity for cavity QED studies

We report on the loading of large ion Coulomb crystals into a linear Paul trap incorporating a high-Finesse optical cavity (F~3200). We show that, even though the 3-mm diameter dielectric cavity mirrors are placed between the trap electrodes and separated by only 12 mm, it is possible to produce in situ ion Coulomb crystals containing more than 100.000 calcium ions of various isotopes and with lengths of up to several millimeters along the cavity axis. We show that the number of ions inside the cavity mode is in principle high enough to achieve strong collective coupling between the ion Coulomb crystal and the cavity field. The results thus represent an important step towards ion trap based Cavity Quantum ElectroDynamics (CQED) experiments using cold ion Coulomb crystals.