Temperature Measurements of Laser-Cooled Ions in a Penning Trap

摘要

Between 10~4 and 10~6 ~9Be~+ ions are trapped in a Penning trap. The ions are laser-cooled to ～millikelvin temperatures, where they form ion crystals. This system is an example of a strongly coupled one-component plasma. By means of Doppler laser spectroscopy we have measured the temperature and heating rate of the plasma. Initially the heating rate is low, 60 +-40 mK/s, but after about 100 ms the plasma heats up rapidly to a few kelvin. The onset of the rapid heating coincides with the solid-liquid phase transition.