External Control of Electron Temperature in Ultra-Cold Plasmas

We discuss our progress towards achieving external control of the electron temperature and the Coulomb coupling parameter of ultra‐cold plasmas. Using a Littman dye laser, we create the plasma by partially photoionizing a dense, cold sample of rubidium atoms in a magneto‐optical trap (MOT). At a controllable time delay, we excite neutral atoms in the plasma to a specific Rydberg state using a narrow bandwidth pulsed laser. We have made very qualitative measurements of the electron temperature as a function of delay from the exciting laser pulses. Some of our results suggest that the plasma is stabilized by the presence of the Rydberg atoms, with a longer lifetime and slower expansion rate than a plasma that evolves directly from a dense Rydberg sample.