Simultaneous observation of ultrafast electron and proton beams in TNSA

Abstract

The interaction of ultra-intense high-power lasers with solid-state targets has been largely studied for the past 20 years as a future compact proton and ion source. Indeed, the huge potential established on the target surface by the escaping electrons provides accelerating gradients of TV/m. This process, called target normal sheath acceleration, involves a large number of phenomena and is very difficult to study because of the picosecond scale dynamics. At the SPARC_LAB Test Facility, the high-power laser FLAME is employed in experiments with solid targets, aiming to study possible correlations between ballistic fast electrons and accelerated protons. In detail, we have installed in the interaction chamber two different diagnostics, each one devoted to characterizing one beam. The first relies on electro-optic sampling, and it has been adopted to completely characterize the ultrafast electron components. On the other hand, a time-of-flight detector, based on chemical-vapour-deposited diamond, has allowed us to retrieve the proton energy spectrum. In this work, we report preliminary studies about simultaneous temporal resolved measurements of both the first forerunner escaping electrons and the accelerated protons for different laser parameters.

Real-Time Electron Solvation Induced by Bursts of Laser-Accelerated Protons in Liquid Water

“…For our experimental parameters the TNSA bunches have been shown to be few ps in duration following drift to the sample under investigation [16]. Considering this, and that the temporal resolution of our detection system is 1.12 ps, proton energies > 4 MeV can be considered to be emitted simultaneously with the prompt x-ray burst [32]. Thus the maximum proton energy can be estimated by their time of flight.…”

Spatial and temporal evolution of electromagnetic pulses from solid target irradiated with multi-hundred-terawatt laser pulse inside target chamber

“…When the high-power laser interacts with solid targets, a large number of escaped hot electrons are generated based on different absorbing and heating mechanisms, such as resonance absorption [1], vacuum heating [2], heating [3], inverse bremsstrahlung [4], and the anomalous skin effect [5]. Some energetic electrons are ejected into the vacuum from the front target surface, and some are accelerated in the backward direction, which creates a separation field called the sheath field behind the target and the accelerating gradient can reach TV m −1 [6].…”

Enhanced polarized proton acceleration driven by femtosecond laser pulses irradiating a micro-structured solid–gas target

“…Currently, the processes [1]. With the advent of laser-plasma accelerators, proton beams with energies of up to 100 MeV have been experimentally produced [5] via hybrid schemes involving radiation pressure acceleration [6] and target normal sheath acceleration (TNSA) [7][8][9]. Meanwhile, other mechanisms of laserproton acceleration, such as the breakout afterburner [10,11] and collision-less shock acceleration (CSA) [12][13][14], have also been studied.…”