Non-LTE Modeling for Laser-Driven Systems
Date | Do, 13.09.2012 | |
Time | 10.15 | |
Speaker | Dr. Howard Scott, Lawrence Livermore National Laboratory, Livermore, CA, USA | |
Location | Universität Bern, Institut für Angewandte Physik, Gebäude exakte Wissenschaften, Hörsaal B116, Sidlerstrasse 5, 3012 Bern | |
Program | The capability to accurately model the properties of matter under non-local thermodynamic equilibrium (non-LTE) conditions is critical to the ability to understand a wide variety of laboratory and astrophysical plasmas. Non-LTE simulations have been used as a tool to understand laser-produced plasmas for several decades. Numerous projects now depend on non-LTE modeling as a design tool. Accordingly, considerable effort has gone into developing this capability, but significant challenges remain. Experiments in laser-driven inertial confinement fusion at the National Ignition Facility (NIF) have recently demonstrated plasma conditions approaching those required for ignition. Non-LTE modeling is a key part of the simulation effort, affecting several aspects of experimental design and diagnostics [1]. The X-rays that drive the capsule arise from high-Z material ablated off the hohlraum wall. Mid-Z dopants in the ablator provide shielding and diagnostic possibilities, but potentially impact the energy balance of the capsule [2]. Looking beyond the NIF, a proposed design for a fusion reactor chamber depends on low-density high-Z gas absorbing X-rays and particles to protect the first wall [3]. X-ray free electron lasers provide some unique capabilities in high energy density physics. The extremely intense pulses can produce plasmas on short enough timescales to retain solid densities [4]. The high intensity and fast timescales also allow for highresolution imaging of biological systems before the structure is destroyed [5]. On more modest scales, laser-driven systems are being developed to provide EUV radiation for lithography to produce the next generation of integrated circuits, and system designers are turning to simulation to understand and optimize these systems. These situations encompass a large range of temperatures, densities and spatial scales. They each emphasize different aspects of atomic physics and present a variety of challenges for non-LTE modeling. We discuss the relevant issues and summarize the current state of the modeling effort for these applications. [1] M.D. Rosen et al, HEDP 7, 180- 190 (2011). [2] B.A. Hammel, et al, Phys. Plasmas 18, 056310 (2011). [3] J.F. Latkowski, et al, Fusion Science and Technology, 60, p. 54-60 (2011). [4] S. Vinko, et al, Nature 482, 59-63 (2012) [5] A. Barty, et al, Nature Photonics 6, 35–40 (2012) This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. |
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Link | www.iap.unibe.ch |