Fluid-solid phase transitions in 3D complex plasmas under microgravity conditions

TL;DR

This study investigates phase transitions in 3D complex plasmas under microgravity, revealing pressure-induced melting and differences from 2D plasma behaviors, with implications for understanding plasma phase diagrams.

Contribution

It provides the first detailed analysis of phase behavior in 3D complex plasmas under microgravity, including structural analysis and phase diagram placement.

Findings

Complex plasmas can melt by increasing gas pressure.

Structural properties indicate phase changes under microgravity.

Differences between 3D microgravity and 2D ground experiments are significant.

Abstract

Phase behavior of large three-dimensional complex plasma systems under microgravity conditions onboard the International Space Station is investigated. The neutral gas pressure is used as a control parameter to trigger phase changes. Detailed analysis of structural properties and evaluation of three different melting/freezing indicators reveal that complex plasmas can exhibit melting by increasing the gas pressure. Theoretical estimates of complex plasma parameters allow us to identify main factors responsible for the observed behavior. The location of phase states of the investigated systems on a relevant equilibrium phase diagram is estimated. Important differences between the melting process of 3D complex plasmas under microgravity conditions and that of flat 2D complex plasma crystals in ground based experiments are discussed.