Theoretical Analysis of Chirped Pulse Effects on Plasma Formation in Water Liquid Jet

TL;DR

This theoretical study investigates how linear chirp influences plasma density in water jets, revealing that negative chirp enhances plasma formation and that dispersion effects can reverse this trend, providing insights for future experimental control.

Contribution

The paper introduces a two-stage theoretical framework that isolates chirp effects on plasma formation in water, separating spectral-phase influences from bandwidth and intensity.

Findings

Negative chirp enhances plasma density compared to positive chirp.

Normal dispersion reduces plasma density as chirp increases.

Longer FTL pulses experience stronger dispersion-induced suppression.

Abstract

We present a theoretical study of how linear chirp controls plasma density in a water jet using a two-stage framework. Stage I solves carrier-population and current equations at a single point, driven by a chirped super-Gaussian pulse. By fixing bandwidth and normalizing for intensity, we isolate a chirp-only response of plasma density, which exceeds unity and shows a consistent advantage for negative over positive chirp. Stage II propagates the field in water via the angular-spectrum method and applies the same equations across space. Normal dispersion reverses the trend: the chirp-only plasma density decreases as chirp grows, negative chirp remains less detrimental, and suppression is strongest for longer FTL pulses (e.g., 80 fs) due to dispersion-induced temporal spreading and spatio-temporal desynchronization. This study separates spectral-phase effects from bandwidth and intensity, yields testable predictions for water jets, and provides a foundation for future experiments and self-consistent propagation models.