Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.

March 15, 2007
12:30 PM

C.E. Simien,
Rice University

Early Dynamics of an Ultrasound Neutral Plasma

Abstract

Ultracold neutral plasmas [1], formed by photoionizing laser-cooled atoms near the ionization threshold, stretch the boundaries of traditional neutral plasma physics. The electron temperature in these plasmas is from 1-1000K and the ion temperature is around 1 K. The density can be as high as 1010 cm-3. Fundamental interest stems from the possibility of creating strongly-coupled plasmas, but recombination, collective modes, and thermalization in these systems have also been studied.

The ultracold plasma group at Rice University recently demonstrated optical absorption imaging of a strontium plasma [2] using the Sr+ 2S1/2 - 2P1/2 transition at 422 nm. Images depict the density profile of the plasma, and probe kinetics on a 50 ns time-scale. The Doppler-broadened ion absorption spectrum measures the ion velocity distribution, which gives an accurate measure of the ion dynamics in the first few hundred nanoseconds after photoionization.

We studied equilibration of strongly coupled ions in an ultracold neutral plasma. By varying the electron temperature, we show that electron screening modifies the equilibrium ion temperature. Also, we observed damped kinetic energy oscillations of the ion kinetic energy, which is a unique feature of equilibration [3].

Current work focuses on laser cooling the plasma. This work is supported by the Department of Energy, National Science Foundation, Alfred P. Sloan Foundation, Research Corporation, and David and Lucille Packard Foundation.