Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmas

Abstract

Time-gated, monoenergetic-proton radiography provides unique measurements of the electric (E) and magnetic (B) fields associated with laser-foil interactions, imploded inertial-confinement-fusion capsules, and laser-irradiated hohlraums. These experiments resulted in the first observations of several new and important features previously unrealized: first, observations of the generation, decay dynamics, instabilities and topology change of megagauss B fields on laser-driven planar plastic foil; second, the observation of radial E fields inside the imploding capsule which are initially directed inward, reverse direction near deceleration onset, and are likely related to the evolution of the electron pressure gradient; third, the observation of many radial filaments with complex electromagnetic field striations, permeating the entire field of view, and fourth, the observation of dynamic E field associated with laser-irradiated gold hohlraums. The physics behind and implications of such observed fields are discussed.

Using intense lasers to simulate aspects of accretion discs and outflows in astrophysics

“…For the disc of the radius of 0.3-1 mm, the embedded magnetic field can be detected by the proton deflectometry, with the probing proton beams generated either by the electrostatic ion acceleration from a thin foil (e.g., Snavely et al 2000) or by imploding an auxiliary fusion capsule (Li et al 2009). In the latter case, the use of a larger-scale laser facility (like Omega) is needed.…”

Modeling hydrodynamics, magnetic fields, and synthetic radiographs for high-energy-density plasma flows in shock-shear targets

“…The plots in the second row are overlaid with magenta contours for the density of the wall material equal to 0.5g/cc. action with a solid target [9,10,12,13]. The plume is continuously launched by the flow inside the shock tube and expands in all directions, with the density gradient to point towards the dense part of the plume, as shown in Fig.…”

“…The Biermann battery effect [8] is known to generate seed magnetic fields in laser driven plasma flows and has been studied extensively in high-energy-density (HED) laser-driven experiments [9][10][11][12][13][14][15][16], but the strength and importance of these fields in the close to or higher than solid density plasmas such as an ICF implosion are not well known. Three-dimensional extendedmagnetohydrodynamic (extended-MHD) simulations of the stagnation phase of ICF including Biermann battery term [8], Nernst term [17] and anisotropic heat conduction in the magnetic field, indicate that self-generated magnetic fields can reach over 10 4 Tesla and can affect the electron heat flow [18].…”

Development of an interpretive simulation tool for the proton radiography technique

“…The latter role of simulating the proton radiograph, given the sampling proton properties and the configuration of plasma and electromagnetic field, can be filled using either a 'ray trace' or Monte-Carlo code. 8,10,11,15,18,25,[33][34][35][36][37][38]40,[58][59][60][61] In the ray trace simulation model, a number of straight-line trajectories (rays) are created at the source some distance from the detector, connecting to the detector. The electromagnetic fields along a given ray are path-integrated and a corresponding net Lorentz deflection is applied to that ray's final position.…”