Investigation of spatiotemporal output beam profile instabilities from differentially pumped capillaries

TL;DR

This paper investigates how pressure gradients in differentially pumped capillaries can induce spatiotemporal beam profile instabilities, with experimental and numerical analysis revealing the transition from laminar to turbulent flow.

Contribution

It provides new insights into the conditions causing beam instabilities in pressure-gradient capillaries and offers predictive guidelines based on combined experimental and numerical data.

Findings

Instabilities occur with a sudden onset during flow transition from laminar to turbulent.

High pressure gradients and gas throughput are key factors in instability development.

Guidelines for predicting instability onset are derived from experimental and numerical results.

Abstract

Differentially pumped capillaries, i.e., capillaries operated in a pressure gradient environment, are widely used for nonlinear pulse compression. In this work, we show that strong pressure gradients and high gas throughputs can cause spatiotemporal instabilities of the output beam profile. The instabilities occur with a sudden onset as the flow evolves from laminar to turbulent. Based on the experimental and numerical results, we derive guidelines to predict the onset of those instabilities and discuss possible applications in the context of nonlinear flow dynamics.