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Felipe Veloso

Publications and source records attributed to Felipe Veloso.

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Influence of Conical Wire Array Geometry on Flow and Temperature Profiles Measured via Thomson Scattering and Optical Techniques

Conical wire arrays with different opening angles are used as load of a 400kA, 1kA/ns generator. The differences in opening angle allow the study of the influence of the array geometry on the jet properties. The characterization of the jets is performed using a combination of advanced diagnostic techniques, including moir\'e schlieren deflectometry, visible self-emission spectroscopy, and optical Thomson scattering. The results reveal that, under the experimental conditions, the plasma jets exhibit electron temperatures ranging from $8$ to $17$ eV, increasing along the axial direction. In contrast, the ion temperature decreases from approximately $35$ eV near the base of the jet to about $20$ eV at higher axial positions. The electron density profile peaks at $\sim 4 \times 10^{18}$ cm$^{-3}$ in the central lower region of the jet and decreases with height exponentially with a characteristic lenght $L_n = $2.86 mm. This behavior is reproducible and independent of the conical array geometry. However, the cone opening angle significantly affect the jet propagation velocity, with larger opening angles producing higher axial velocities ($V_{\phi=40^\circ} \approx 125\pm3$ km/s, $V_{\phi=20^\circ} \approx 98\pm5$ km/s), demonstrating that the cone geometry provides effective control over the jet propagation velocity.

physics.plasm-ph

Laser-Driven Annular Shock Waves as Laboratory Analogues of $w$CDM Cosmologies and Cosmological Gravitational Waves

We demonstrate that the experimental evolution of an annular, laser-driven plasma shock wave, expanding over time and undergoing self-interaction gives rise to multiple shock structures that evolve analogously to a multicomponent cosmological universe. Different propagation trajectories along the shock surface correspond to various forms of $w$CDM cosmologies, enabling the study of scenarios ranging from simple radiation- or matter-dominated universes to those including dark energy. We further show that the dynamics of the Mach stems approximately follows a Hubble-like law. Additionally, perturbations in the shock fronts serve as experimental analogues of cosmological gravitational perturbations in a matter-dominated universe. This work opens a new experimental pathway for classically simulating complex cosmological models and gravitational waves at macroscopic scales in the laboratory.

physics.plasm-ph