skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Design of a new turbulent dynamo experiment on the OMEGA-EP

Abstract

Turbulent dynamos that exponentially amplify initially small, seed magnetic fields are crucial in magnetizing the Galaxy and beyond. Until now, the ideal environment for turbulent dynamos to grow has been difficult to recreate. In a new approach, we leverage the long pulse capability of the OMEGA-EP laser to recreate the highly conductive and inviscid ( Re m ~ 5500 , Pr m 1 ) growth environment of the turbulent dynamo within the magnetized plasma jet ablated from a simple cone target of CH plastic. In 3-D FLASH simulations of our scheme, we find that the ideal dynamo environment is a typically ~1 mm 3, 1.5 keV hot spot where the laser beams intersect to produce maximum direct heating of the jet plasma. The dynamo environment is maintained from the onset of steady flows through the ~10 ns length of the laser pulse. For a plasma vorticity of 0.3–3.0 ns –1 and a dynamo active over ~5 ns, the magnetic energy increases on an exponential trajectory by more than a decade. Fourier analysis reveals that the dynamo progressively saturates up to E B / E K ~ 20 % from small scales k 30 cm -1 to large in the time it is sustained. We find robust agreement between the evolution of magnetic energy spectra extracted from the FLASH physics simulation and that derived from synthetic sheath-accelerated proton deflectometry images, thereby demonstrating that the dynamo activity can be quantified in a real experiment.

Authors:
 [1];  [1];  [1]; ORCiD logo [1];  [1];  [1];  [1];  [2];  [3]; ORCiD logo [3];  [3];  [4]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Michigan, Ann Arbor, MI (United States). Climate and Space Sciences and Engineering Dept.
  3. Univ. of Michigan, Ann Arbor, MI (United States). Climate and Space Sciences and Engineering Dept.
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); LANL Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1503193
Report Number(s):
LA-UR-18-30966
Journal ID: ISSN 1070-664X
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 3; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 79 ASTRONOMY AND ASTROPHYSICS; turbulence; turbulent dynamo; computational fluid dynamics; magnetohydrodynamics; laboratory astrophysics; OMEGA-EP

Citation Formats

Liao, Andy Sha, Li, Shengtai, Li, Hui, Flippo, Kirk, Barnak, Daniel, Kelso, Kwyntero Van, Fiedler Kawaguchi, Codie, Rasmus, Alexander, Klein, Sallee, Levesque, Joseph, Kuranz, Carolyn, and Li, Chikang. Design of a new turbulent dynamo experiment on the OMEGA-EP. United States: N. p., 2019. Web. doi:10.1063/1.5081062.
Liao, Andy Sha, Li, Shengtai, Li, Hui, Flippo, Kirk, Barnak, Daniel, Kelso, Kwyntero Van, Fiedler Kawaguchi, Codie, Rasmus, Alexander, Klein, Sallee, Levesque, Joseph, Kuranz, Carolyn, & Li, Chikang. Design of a new turbulent dynamo experiment on the OMEGA-EP. United States. doi:10.1063/1.5081062.
Liao, Andy Sha, Li, Shengtai, Li, Hui, Flippo, Kirk, Barnak, Daniel, Kelso, Kwyntero Van, Fiedler Kawaguchi, Codie, Rasmus, Alexander, Klein, Sallee, Levesque, Joseph, Kuranz, Carolyn, and Li, Chikang. Thu . "Design of a new turbulent dynamo experiment on the OMEGA-EP". United States. doi:10.1063/1.5081062. https://www.osti.gov/servlets/purl/1503193.
@article{osti_1503193,
title = {Design of a new turbulent dynamo experiment on the OMEGA-EP},
author = {Liao, Andy Sha and Li, Shengtai and Li, Hui and Flippo, Kirk and Barnak, Daniel and Kelso, Kwyntero Van and Fiedler Kawaguchi, Codie and Rasmus, Alexander and Klein, Sallee and Levesque, Joseph and Kuranz, Carolyn and Li, Chikang},
abstractNote = {Turbulent dynamos that exponentially amplify initially small, seed magnetic fields are crucial in magnetizing the Galaxy and beyond. Until now, the ideal environment for turbulent dynamos to grow has been difficult to recreate. In a new approach, we leverage the long pulse capability of the OMEGA-EP laser to recreate the highly conductive and inviscid (Rem~5500, Prm≳1) growth environment of the turbulent dynamo within the magnetized plasma jet ablated from a simple cone target of CH plastic. In 3-D FLASH simulations of our scheme, we find that the ideal dynamo environment is a typically ~1 mm3, ≳1.5 keV hot spot where the laser beams intersect to produce maximum direct heating of the jet plasma. The dynamo environment is maintained from the onset of steady flows through the ~10 ns length of the laser pulse. For a plasma vorticity of 0.3–3.0 ns–1 and a dynamo active over ~5 ns, the magnetic energy increases on an exponential trajectory by more than a decade. Fourier analysis reveals that the dynamo progressively saturates up to EB/EK~20% from small scales k≳30 cm-1 to large in the time it is sustained. We find robust agreement between the evolution of magnetic energy spectra extracted from the FLASH physics simulation and that derived from synthetic sheath-accelerated proton deflectometry images, thereby demonstrating that the dynamo activity can be quantified in a real experiment.},
doi = {10.1063/1.5081062},
journal = {Physics of Plasmas},
number = 3,
volume = 26,
place = {United States},
year = {2019},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share: