Electronic detection of collective modes of an ultracold plasma

TL;DR

This paper introduces a novel electronic detection method to measure plasma oscillations in ultracold plasmas, revealing how charge imbalance influences resonant frequencies and confirming theoretical predictions about edge modes.

Contribution

It presents a new technique for directly detecting plasma oscillations that avoids heating effects and tests the impact of plasma neutrality on collective modes.

Findings

Charge imbalance significantly affects resonant frequency

Electronic detection avoids heating and evaporation effects

Results agree with predictions of edge mode coupling

Abstract

Using a new technique to directly detect current induced on a nearby electrode, we measure plasma oscillations in ultracold plasmas, which are influenced by the inhomogeneous and time-varying density and changing neutrality. Electronic detection avoids heating and evaporation dynamics associated with previous measurements and allows us to test the importance of the plasma neutrality. We apply dc and pulsed electric fields to control the electron loss rate and find that the charge imbalance of the plasma has a significant effect on the resonant frequency, in excellent agreement with recent predictions suggesting coupling to an edge mode.