Electron density measurement of a colliding plasma using soft-x-ray laser interferometry

Abstract

The understanding of the collision and subsequent interaction of counter-streaming high-density plasmas is important for the design of indirectly-driven inertial confinement fusion (ICF) hohlraums. We have employed a soft x-ray Mach-Zehnder interferometer. using a Ne-like Y xray laser at 155 A as the probe source, to study interpenetration and stagnation of two colliding plasmas. We observed a peaked density profile at the symmetry axis with a wide stagnation region with width of order 100 pm. We compare the measured density profile with density profiles calculated by the radiation hydrodynamic code LASNEX and a multi-specie fluid code which allows for interpenetration. The measured density profile falls in between the calculated profiles using collisionless and fluid approximations. By using different target materials and irndiation configurations, we can vary the collisionality of the plasma. We hope to use the soft x-ray laser interferometry as a mechanism to validate and benchmark our numerical codes used for the design and analysis of high-energy-density physics experiments.

XUV diagnostics of colliding laser-produced magnesium plasmas

“…These may be of collisionless type in which case collective plasma effects occur or they are collision dominated. Depending upon collisionality of the plasmas, which in turn depends on temperature, density and ionic charge, varying amounts of interpenetration are predicted [19]. In this paper we report the characteristics of colliding laser-produced magnesium plasmas studied using XUV photography and XUV spectroscopy.…”

“…Despite considerable experimental and theoretical progress in the dynamics of single laser-produced plasmas, little attention has been paid to the study of the nature and of the dynamics of laser-produced colliding plasmas. Moreover, most of the colliding plasma experiments were carried out employing high-intensity lasers (>10 13 W cm −2 ) [19,24]. However, experiments with low-intensity lasers are extremely valuable for elucidating underlying science.…”

“…Laser-produced colliding plasmas find potentially attractive applications in the field of x-ray lasers, in stimulated Raman scattering experiments, and they are of relevance for the design of inertial confinement fusion (ICF) hohlraums [17][18][19]. In addition to these applications, the interpenetration of two plasmas occurs also in astrophysical systems, for example after a super nova explosion ejects plasma into the interstellar medium, when releasing barium into the solar wind, or in the interaction of comets with the solar wind [20,21].…”

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

“…Related studies include counter-streaming laser-produced plasmas supporting hohlraum design for indirect-drive inertial confinement fusion [17][18][19] and for studying astrophysically relevant shocks, [20][21][22][23][24] colliding plasmas using wire-array Z pinches, 25,26 and applications such as pulsed laser deposition 27 and laser-induced breakdown spectroscopy. 28 Primary issues of interest in these studies include the identification of shock formation, the formation of a stagnation layer [29][30][31] between colliding plasmas, and the possible role of two-fluid and kinetic effects on plasma interpenetration.…”

Extremely compact soft X-ray lasers based on capillary discharges

“…The elongated gold-coated mirrors redirect the beam towards the second grating where they are recombined and the interference pattern is generated. Advantages of the DGI scheme over other amplitude-division soft X-ray interferometers based on thin-film beam splitters [10,14] include a higher throughput (B6% percent per arm) and a significantly increased resistance of the beam splitters to plasma debris. A Si/Sc multilayers optics system was used to image the plasma onto a CCD/MCP detector setup with 51.2 Â magnification.…”