Proton imaging: a diagnostic for inertial confinement fusion/fast ignitor studies

Abstract

Proton imaging is a recently proposed technique for diagnosis of dense plasmas, which favourably exploits the properties of protons produced by high-intensity laser-matter interaction. The technique allows the distribution of electric fields in plasmas and around laser-irradiated targets to be explored for the first time with high temporal and spatial resolution. This leads to the possibility of investigating as yet unexplored physical issues. In particular we will present measurements of transient electric fields in laser-plasmas and around laserirradiated targets under various interaction conditions. Complex electric field structures have been observed in long-scale laser-produced plasmas, while global target charge-up and growth of electromagnetic instabilities have been detected following ultraintense interactions with solid targets.

Collisionless electrostatic shock generation using high-energy laser systems

“…A main laser pulse (1064 nm, 470 ps, intensity I ∼ 10 15 W/cm 2 ) was focused onto a metal foil (25 µm thick Tungsten or aluminum foil), and a high-density ablation plasma (∼10 18 cm −3 ) interacted with a low-density ambient plasma (∼10 15 cm −3 ) produced via photoionization (mainly driven by the thermal radiation from the target) of the residual gas (∼10 −3 mbar) in the target chamber. The electric field distribution and the shocks' structures have been reconstructed by proton imaging technique [66,102]. A second laser beam (1064 nm, 300 fs, I ∼ 10 18 W/cm 2 ) was focused onto a thin Tungsten target to generate a proton beam.…”

“…We have conducted the Weibel-instability mediated collisionless EM shock experiments with Omega and Omega EP laser systems (Rochester U., U.S.A), and measured plasma parameters such as electron and ion temperatures, electron density, and flow velocity of counter-streaming plasmas [60][61][62] with collective Thomson scattering (CTS) [63], and filamentary structure produced by the Weibel instability [62,64,65] with proton radiography [66,67]. Now the NIF experiment is going on.…”

Numerical simulation of laser ion acceleration at ultra high intensity

“…Laser applications are used in proton radiography [1], fast ignition [2], hadrontherapy [3], [4], radioisotope production [5] and laboratory astrophysics [6]. During the laser-target interaction, ions are accelerated by different physical processes, depending on the region of the target.…”

Novel diagnostic of low-Z shock compressed material

“…The particular properties of laser-driven protons beam (small source, high degree of collimation, short duration) make them of great interest for radiographic applications [6]. The proton profile in the beam should undergo due to collisional stopping power the density profile in the crossed matter leading to the determination of the density in the shock.…”