A Model for Magnetic Flux Generation in ICF Hot-Spots
ORAL
Abstract
Self-generated magnetic fields are expected to be generated in excess of 10,000T in ICF hot-spots [1]. A model for magnetic flux generation is presented, showing that more flux is expected around large amplitude and high mode perturbations. The model compares favorably with Gorgon extended-MHD simulations, allowing for greater understanding of which target designs will be susceptible to MHD effects. For example, the model can be used to ascertain when most magnetic flux is expected to be generated. If generation is weighted more towards early times, then more high-mode magnetic field loops will be generated; even if the high-mode perturbations are ablatively stabilized at later times, the high mode magnetic field will still be present.
Hot-spot heat-flow can become significantly magnetized, resulting in enhanced energy loss through Righi-Leduc heat-flow [1]. Simulations suggest that ignoring MHD leads to under-estimates of hot-spot perturbation growth, with differences greater than 5μm observed across a wide range of mode numbers and amplitudes. The sensitivity of these results to transport coefficients will also be presented, advocating for a move to newer formulations [2,3] over those suggested by Epperlein & Haines [4].
[1]- Walsh et al. PRL (2017)
[2]- Sadler, Walsh, Li, PRL (2021)
[3]- Davies, Wen, Ji, Held, PoP (2021)
[4]- Epperlein & Haines , PoF (1986)
Hot-spot heat-flow can become significantly magnetized, resulting in enhanced energy loss through Righi-Leduc heat-flow [1]. Simulations suggest that ignoring MHD leads to under-estimates of hot-spot perturbation growth, with differences greater than 5μm observed across a wide range of mode numbers and amplitudes. The sensitivity of these results to transport coefficients will also be presented, advocating for a move to newer formulations [2,3] over those suggested by Epperlein & Haines [4].
[1]- Walsh et al. PRL (2017)
[2]- Sadler, Walsh, Li, PRL (2021)
[3]- Davies, Wen, Ji, Held, PoP (2021)
[4]- Epperlein & Haines , PoF (1986)
*This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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Publication: Walsh & Clark, "Biermann Battery Magnetic Fields in ICF Capsules: Total Magnetic Flux Generation" (submitted 2021)
Walsh, Sadler, Davies, "Updated Magnetized Transport Coefficients: Impact on Laser-Plasmas with Self-Generated or Applied Magnetic Fields" (submitted 2021)
Presenters
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Chris A Walsh
- Lawrence Livermore National Laboratory
- Lawrence Livermore Natl Lab
- Lawrence Livermore National Lab