Ice Particles Trapped by Temperature Gradients at mbar Pressure

TL;DR

This study demonstrates that ice particles in a low-pressure environment can be trapped and levitated using temperature gradients created by different reservoirs, enabling detailed experimental investigation.

Contribution

It introduces a novel method for trapping ice particles using temperature gradients at mbar pressure, combining experimental observations with modeling of thermophoretic and photophoretic forces.

Findings

Ice particles are stably trapped by temperature gradients.

Particles can be held for minutes for further study.

The trapping mechanism involves thermophoresis, photophoresis, and gravity.

Abstract

In laboratory experiments we observe that ice particles (\leq100 \mu m) entrained in a low pressure atmosphere (~1 mbar) get trapped by temperature gradients between three reservoirs at different tempertature. Confining elements are a peltier element at 250 K (bottom), a liquid nitrogen reservoir at 77 K (top) and the surrounding vacuum chamber at 293 K. Particle levitation and trapping is modeled by an interplay of thermophoresis, photophoresis and gravity. A number of ice particles are trapped simultaneously in close spatial distance to each other at least up to minutes and are accessible for further experiments.