Title: Enhanced collisionless laser absorption in strongly magnetized plasmas

Abstract

We report that strongly magnetizing a plasma adds a range of waves that do not exist in unmagnetized plasmas and enlarges the laser-plasma interaction (LPI) landscape. In this paper, we use particle-in-cell simulations to investigate strongly magnetized LPI in one dimension under conditions relevant for magneto-inertial fusion experiments, focusing on a regime where the electron-cyclotron frequency is greater than the plasma frequency and the magnetic field is at an oblique angle with respect to the wave vectors. We show that when electron-cyclotron-like hybrid wave frequency is about half the laser frequency, the laser light resonantly decays to magnetized plasma waves via primary and secondary instabilities with large growth rates. These distinct magnetic-field-controlled instabilities, which we collectively call two-magnon decays, are analogous to two-plasmon decays in unmagnetized plasmas. Since additional phase mixing mechanisms are introduced by the oblique magnetic field, collisionless damping of large-amplitude magnetized waves substantially broadens the electron distribution function, especially along the direction of the magnetic field. During this process, energy is transferred efficiently from the laser to plasma waves and then to electrons, leading to a large overall absorptivity when strong resonances are present. The enhanced laser energy absorption may explain hotter-than-expected temperatures observed in magnetized lasermore » implosion experiments and may also be exploited to develop more efficient laser-driven x-ray sources.« less

Authors:

Manzo, Lili  ^[1];

• Search DOE PAGES for author "Manzo, Lili"
• Search DOE PAGES for ORCID "0000-0003-4935-4910"

Edwards, Matthew R.  ^[2];

• Search DOE PAGES for author "Edwards, Matthew R."
• Search DOE PAGES for ORCID "0000-0002-9701-0736"

Shi, Yuan  ^[1]

• Search DOE PAGES for author "Shi, Yuan"
• Search DOE PAGES for ORCID "0000-0002-3284-4449"

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+ Show Author Affiliations

1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
2. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Stanford University, CA (United States)

Publication Date:

Fri Nov 04 00:00:00 EDT 2022

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program

OSTI Identifier:

1897356

Alternate Identifier(s):

OSTI ID: 1897247

Report Number(s):

LLNL-JRNL-834357
Journal ID: ISSN 1070-664X; 1052712; TRN: US2310784

Grant/Contract Number:  

AC52-07NA27344; 19-ERD-038; 20-ERD-057

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Plasmas

Additional Journal Information:

Journal Volume: 29; Journal Issue: 11; 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; wave particle interactions; cyclotron response; forward scattering; particle-in-cell method; plasmas; lasers; magnons