Hybrid simulation of Alfv\'en wave parametric decay instability in a laboratory relevant plasma

TL;DR

This paper presents a novel hybrid simulation approach to study the parametric decay of large-amplitude Alfvén waves in a laboratory plasma, identifying thresholds for instability and providing insights for future experiments.

Contribution

It introduces a hybrid simulation method with realistic parameters to analyze Alfvén wave decay, bridging the gap between theory and laboratory observation.

Findings

Identified threshold amplitudes and frequencies for instability.

Validated threshold behaviors with simple theoretical models.

Demonstrated the simulation's potential for guiding laboratory experiments.

Abstract

Large-amplitude Alfv\'en waves are subject to parametric decays which can have important consequences in space, astrophysical, and fusion plasmas. Though the Alfv\'en wave parametric decay instability was predicted decades ago, observational evidence is limited, stimulating considerable interest in laboratory demonstration of the instability and associated numerical modeling. Here, we report novel hybrid simulation of the Alfv\'en wave parametric decay instability in a laboratory relevant plasma (based on the Large Plasma Device), using realistic wave injection and wave-plasma parameters. Considering only collisionless damping, we identify the threshold Alfv\'en wave amplitudes and frequencies required for triggering the instability in the bounded plasma. These threshold behaviors are corroborated by simple theoretical considerations. Other effects not included in the present model such as finite transverse scale and ion-neutral collision are briefly discussed. These hybrid simulations demonstrate a promising tool for investigating laboratory Alfv\'en wave dynamics that can provide guidance for future laboratory demonstration of the parametric decay instability.