Synchronized Catastrophic Collapse and Extreme Intensity Amplification of Ultra-Intense Pulses in Near-Resonance Magnetized Plasma

Abstract

Ultra-high field intensities are essential for developing high-energy-density physics and compact plasma accelerators, but they are essentially constrained by the limitations of focusing distance and nonlinear efficiency. We present a theoretical model for extreme laser energy concentration in under-dense plasma that shows a highly effective, magnetically supported pathway. We demonstrate a fundamental, nonlinear enhancement of the relativistic self-focusing (RSF) mechanism by adjusting an external magnetic field close to the cyclotron resonance (Ce=0.7). Over a remarkably short distance of 1.25 Rayleigh lengths, the pulse is driven into a catastrophic, coupled collapse by this magnetic enhancement. Significant temporal self-compression (0.60) and simultaneous spatial confinement (0.05) are the outcomes of the dynamics. Importantly, this combined confinement results in a localized peak intensity amplification factor greater than 103 compared to the initial state. This work offers a clear, practical blueprint for upcoming laser-plasma experiments and validates a reliable and compact technique for producing petawatt-scale power densities.