Thermal self-oscillations in radiative heat exchange

TL;DR

This paper demonstrates that two parallel plates of SiO₂ and VO₂ can exhibit self-induced temperature oscillations due to radiative heat exchange, driven by VO₂'s phase transition, with potential applications in thermal management.

Contribution

It introduces a novel mechanism of thermal self-oscillations caused by phase transition in VO₂ during radiative heat exchange, analyzed via fluctuational electrodynamics.

Findings

Temperature oscillations occur around VO₂'s phase transition point.

Oscillation period is approximately 2 seconds at 500 nm vacuum gap.

Amplitude of oscillations is about 4 Kelvin.

Abstract

We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO$_2$ and VO$_2$ which exchange heat by thermal radiation in vacuum. The non-linear feedback in the self-oscillating system is provided by metal-insulator transition in VO$_2$. Using the method of fluctuational electrodynamics we show that under the action of an external laser of a constant power, the temperature of VO$_2$ plate oscillates around its phase transition value. The period and amplitude of oscillations depend on the geometry of the structure. We found that at 500\,nm vacuum gap separating bulk SiO$_2$ plate and 50 nm thick VO$_2$ plate, the period of self-oscillations is 2 s and the amplitude is 4 K which is determined by phase switching at threshold temperatures of phase transition.