11.19 LLE Meeting Results

Adam,

Three people have expressed some interest in AstroBEAR: Riccardo, Radha and Suxing. The main issue is whether anybody would have time to work with a new code. That might be influenced by the level of support that you can supply and if we can find a student willing to work on these problems.

Riccardo would want to try a variation of the problem that you were originally looking at (presumably with a corrected treatment of the boundary conditions). Apparently no additional physics modules would be required. His comments were:

I am interested in this code if I can find at least one problem that is very well defined, doesn't require upgrades to the code and for which our codes cannot provide an answer. I think I may have found it, 3D ablative RT in a slab with gravity. That could tell us if there is a major differentce in 3D multimode ablative RT with respect to 2D. It uses the same input I already gave to Adam years ago.

Radha and Suxing might be interested to use AstroBEAR to look at other problems that would require developing some additional physics modules. A description of these is in the attachment.

Possible physics issues that can be addressed with AstroBEAR Nov 9, 2012

  1. B. Radha and S. X. Hu

Problem classes fall under either short wavelength studies or 3D studies. Problems requiring some form of laser energy deposition, such as study of imprint or evolution of target defects are not listed below.

  1. Short wavelength mixing at plastic (CH) gas (deuterium or deuterium/tritium etc.) interfaces for different Atwood numbers and materials with different atomic numbers, during the deceleration phase of implosion and hot-spot formation.

Physics issue: How significant is the classical interface for determining target performance (fusion yields)? Physics needed:

  1. Implicit heat conduction – Can we get away with explicit if we limit time steps (probably not)
  2. Multigroup diffusive radiation transport – Radiation plays an important role in setting up the density profile and the growth of Rayleigh –Taylor at the related unstable interface influences the growth at the material interface.

Scope:

  1. This problem is not accessible by HYDRA.
  2. While radiation is not critical to initial studies, they need to be added eventually to realistically model plastic shell implosions.
  3. How do we know that numerical noise is not overwhelming the problem?
  1. 3D assembly of hotspot

Physics issue: How does 3D physics influence the assembly of the hotspot in cryogenic DT-implosions? Physics needed:

  1. Implicit heat conduction – Can we get away with explicit if we limit time steps (probably not)
  2. Alpha transport

Scope:

  1. This problem can be tackled by HYDRA though the effort at Livermore seems to be more toward modeling the integrated implosions as opposed to trying to understand the basis of the physics.
  2. Where will the computational resources come from?
  1. The effect of magnetic fields in implosions (3D problem)

Physics issue: Do magnetic fields influence heat conduction in the compressed core – particularly for Polar Drive implosions where we see significant variations in the symmetry of the hot spot in OMEGA implosions.

Physics needed:

  1. Implicit heat conduction – Can we get away with explicit if we limit time steps (probably not)
  2. Self-generated magnetic fields.
  3. Effect of magnetic fields on heat conduction coefficients.

Scope:

  1. This problem is likely unique to LLE and Polar Drive.
  2. Where will the computational resources come from?
  1. Studying the magnetic field reconnection in laboratory astrophysics NLUF experiments on OMEGA (this could be a possible application in not-so-near future)

Physics issue: How magnetic field reconnection starts and how magnetic energy is released as kinetic energy of particles?

Physics needed:

  1. Self-generated and/or external B-field evolution
  2. Multigroup diffusive radiation transport

Scope:

  1. This is one of the grand challenges in astrophysics and is unrelated to ICF. It belongs to the basic science category. However, it may relate to LLE through reconnection experiments being conducted on EP.
  2. The 3D nature might be crucial.

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