Ion-motion-driven enhancement of energy coupling and stability in relativistic laser-microchannel interaction

TL;DR

This paper introduces a new self-organized regime in laser-driven microchannels where ion motion enhances energy coupling and stability, demonstrated through 3D simulations and similarity parameters.

Contribution

It reveals how ion motion can be harnessed to improve energy transfer and stability in laser-microchannel interactions, expanding understanding of plasma behavior.

Findings

Ion motion facilitates stronger peak fields and higher charge conversion.

Similarity parameters govern the interaction regime, linking pulse and channel scales.

Lower-intensity experiments can inform high-intensity facility designs.

Abstract

For sufficiently short relativistic-intensity laser pulses, the disparity in time scales for electron and ion motion causes ions to behave as a fixed, neutralizing background. As the pulse duration or intensity is increased, ion motion becomes important, leading to instability in uniform plasmas but more complex, and potentially desirable behavior in structured targets. In this work, we introduce a new self-organized regime in laser-driven microchannels wherein ion motion facilitates stronger peak fields and high charge and photon conversion efficiency. 3-D particle-in-cell simulations demonstrate that the qualitative laser-microchannel interaction regime is governed by similarity parameters relating the pulse duration, spot size, and intensity to channel scales. The observed similarity suggests that lower-intensity experiments can inform designs for next-generation facilities, where the high-field, highly-radiative properties of the self-organized regime are especially desirable.