Design of Experiments Relevant to Accreting Stream-Disk Impact in ...

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Florida State University, 400 Dirac Science Library, Tallahasse FL, 32306. Background on ... National Laser User Facility Program in NNSA-DS and by the. Predictive ... X-ray radiography – morphology, mass density. Streaked Optical ...
Design of Experiments Relevant to Accreting Stream-Disk Impact in Interacting Binaries CM Krauland1, RP Drake1, CC Kuranz1, RP Young1, MJ Grosskopf1, DC Marion1, T Plewa2 1. University of Michigan, 2455 Hayward St. Ann Arbor, MI, 48109 2. Florida State University, 400 Dirac Science Library, Tallahasse FL, 32306 Background on Cataclysmic Binary systems Cataclysmic Binaries (CBs) generally comprise of a white dwarf (WD) and a companion low mass main-sequence star. The nature of CBs depends primarily on the gas flow from the cool secondary star to the white dwarf. •  Gas streams towards WD but is diverted around it with excess angular momentum •  The stream produces a ring in lowest energy state

Experimental Primary Diagnostics

Abstract In many Cataclysmic Binary systems, mass transfer via Roche lobe overflow onto an accretion disk occurs. This produces a hot spot from the heating created by the supersonic impact of the infalling flow with the rotating accretion disk, which can produce a radiative reverse shock in the infalling flow. This collision region has many ambiguities as a radiation hydrodynamic system. Depending upon conditions, it has been argued (Armitgae & Livio, ApJ 493, 898) that the shocked region may be optically thin, thick, or intermediate, which has the potential to significantly alter its structure and emissions. Laboratory experiments have yet to produce colliding flows that create a radiative reverse shock or to produce obliquely incident colliding flows, both of which are aspects of these binary systems. We have undertaken the design of such an experiment, aimed at the Omega-60 laser facility. The design elements include the production of postshock flows within a dense material layer or ejecta flows by release of material from a shocked layer. Obtaining a radiative reverse shock in the laboratory requires producing a sufficiently fast flow (> 100 km/s) within a material whose opacity is large enough to produce energetically significant emission from experimentally achievable layers. In this poster we will discuss the astrophysical context, the experimental design work we have done, and the challenges of implementing and diagnosing an actual experiment.

Long-term Experimental Question: In colliding winds where a less dense stream impacts a denser stream, how do the morphology and light curves vary as the optical depth of the shocked layer changes from thin to thick?

•  The accretion disc becomes fully formed

Primary Experimental Goal: After a plasma stream impacts a wall, how does the reverse radiative shock morphology appear and what does its spectrum look like?

The supersonic gas stream that continues to flow, now impacts the outer edge of the accretion disc, forming a hot spot or bright spot, evidenced in spectral data

Artist rendition – M. Garlick

Optical depth vs. structure and emission In the collision of the stream and disc, two shocks become established, Ws and Wd The reverse shock in the stream, Ws can be quite radiative, contributing to the name hot spot

Simulations using different EOS’s to distinguish these systems, show very different structure in the hot spot region Isothermal EOS

www.PosterPresentations.com

general design of streak camera

SOP image of radiative shock in H traveling down tube

PRIMARY DIAGNOSTICS – Laser conditions:

Grid for spatial fiducial

•  10 beams •  ~400 J/beam

to diagnostics

•  1 ns square pulse

X-ray radiography – morphology, mass density Streaked Optical Pyrometer (SOP) – position vs. time thermal self emission, characterized for temperature Dante – time-resolved x-ray spectrometer for light curve

Stalk to target positioner

•  1015 W/cm2

Dante Diagnostic View

Issues: enough signal?, resolution Kuranz, Dec 2009

Future Work These experiments will be carried out in August 2010 on Omega Provided we can produce and diagnose a reverse radiative shock, later experiments for this platform include:

SECONDARY DIAGNOSTICS – HENWAY – time-integrated x-ray spectrometer for backlighter foil X-ray Framing Camera – for beam spot on backlighter

preheat Laser drive beams

Diagnostic Design Geometry SOP Diagnostic View Stalk

quartz

Orthogonal to tube SOP for propagation of stream and shock

Ungated X-ray Radiograhy Diagnostic View J. Smak 1985

top view Laser drive beams

Stalk

diagnostic slit, streaked relative to longer dimension

Orthogonal to tube radiography for side view of shock

Hamamatsu 2008

On OMEGA, SOP data recorded on CCD

Target in OMEGA-60 chamber

side view

Armitgae & Livio 1998

Streaked Optical Pyrometer

Radiative ion temp spike

Simulations suggest design produces a radiative reverse shock that persists for ~10 ns, averages ~50-100 um thick by the end of its radiative phase

Acrylic body

disc

Issues: contrast, resolution, timing

Reverse shock

disc

Adiabatic EOS (optically thick)

POSTER TEMPLATE BY:

Adiabatic EOS

stream

- hot bulge extending along rim of the disc -  some overflowing but not coherent stream -  even in the absence of radiative cooling, the temperature declines rapidly stream downstream of impact

Film image of laserdriven radiative Doss, Oct 2008 shock

Transmitted shock

BASIC DESIGN – Laser produced Sn plasma streamed into vacuum incident on thick quartz or Al wall

Optical depth of shocked regions can be linked to the mass accretion rate such that: -  Low accretion rate systems  optically thin to intermediate - High accretion rate systems  optically thick

- stream flows over disc - region downstream of collision possesses significant inward velocity

Point Projection Radiography

Proof of Principle Experiment

•  Viscous processes and continued conservation of momentum cause ring to spread

Isothermal EOS (optically thin)

Experiment at point of diagnosing (~20 ns after beams turn off

Acrylic body

Au shielding Laser drive beams

•  colliding plasma stream with another denser stream •  changing scale heights of colliding streams to diagnose difference in interaction •  changing materials for different optical depths

diagnostic window for x-rays

Acknowledgements

Au shielding from laser drive beams and plasma plume at ablation for ungated film

This work is funded by the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, by the National Laser User Facility Program in NNSA-DS and by the Predictive Sciences Academic Alliances Program in NNSA-ASC. The corresponding grant numbers are DE-FG52-09NA29548, DE-FG52-09NA29034, and DE-FC52-08NA28616.