Optimization of power compression and stability of relativistic and ponderomotive self-channeling of 248 nm laser pulses in underdense plasmas

The controlled formation in an underdense plasma of stable multi-PW relativistic micrometer-scale channels, which conduct a confined power at 248 nm exceeding 104 critical powers and establish a peak channel intensity of ∼1023 W/cm2, can be achieved with the use of an appropriate gradient in the electron density in the initial launching phase of the confined propagation. This mode of channel formation optimizes both the power compression and the stability by smoothing the transition from the incident spatial profile to that associated with the lowest channel eigenmode, the dynamically robust structure that governs the confined propagation. A chief outcome is the ability to stably conduct coherent energy at fluences greater than 109 J/cm2