Electrostatic electron oscillations and damping in an ultracold plasma

Jacob Roberts, Wei‐Ting Chen, Craig Witte

Wei‐Ting Chen, Craig Witte, Jacob Roberts

Wei‐Ting Chen, Jacob Roberts

Kevin A. Twedt, S. L. Rolston

Wei-Ting Chen, Craig Witte, Jacob Roberts

Applying a short electric field pulse to an ultracold plasma induces an electron plasma oscillation. This manifests itself as an oscillation of the electron center of mass around the ion center of mass in the ultracold plasma. In general, the oscillation can damp due to either collisionless or collisional mechanisms, or a combination of the both. To investigate the nature of oscillation damping in ultracold plasmas, we developed a molecular dynamics model of the ultracold plasma electrons. Through this model, we found that depending on the neutrality of the ultracold plasma and the size of an applied DC electric field, there are some parameter ranges where the damping is primarily collisional and some primarily collisionless. We conducted experiments to compare the measured damping rate with theory predictions and found them to be in good agreement. Extension of our measurements to different parameter ranges should enable studies for strong-coupling influence on electron-ion collision rates.

Jacob Roberts

tion of the electrons. This oscillation will damp after the application of the electric eld pulse. We have found that under certain achievable experimental conditions, this damping can be dominated by the electron-ion collision rate. We have measured this damping rate experimentally under these conditions and thus can compare it to theoretical predictions. We will present our measurement technique and results. In addition, we will discuss extensions of this technique to measurements of electron temperature, to investigating strong-coupling physics in the electron component of an ultracold plasma, and to measuring the electron-ion collision rate when the electrons are highly magnetized.