Publication

Nonstandard Collapse of Strong Langmuir Turbulence: Constraints on Its Occurrence and Observation in the Solar Corona

2025

Abstract

We present fully kinetic simulations of strong Langmuir turbulence (SLT) excited by electron beams with solar coronal conditions. We study two different collapsing processes within the parameter regimes of classical modulational instability (MI) and electron MI (EMI). For the first time, we simulated the EMI-induced collapse of moving multiple packets that is referred to as the non-Zakharov (or nonstandard) process here. We also simulated the classical Zakharov collapse of SLT induced by MI. During the early stage of the nonstandard collapse, the propagating packets get localized to form density cavities with depths of less than 0.1 n0 (the background electron density) that are too shallow to trap the packets. As a result, a majority of the packet energy runs away, undergoes a secondary collapse, and generates stationary packets with cavities. During the damping stage, the packets accelerate the background electrons to form numerous bidirectional propagating jets that distribute asymmetrically. This study reveals novel features of SLT collapse under coronal conditions.

Official source

https://infoscience.epfl.ch/entities/publication/5da53828-ef3a-43d2-9ff4-4bcf31691a36

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2025

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/5da53828-ef3a-43d2-9ff4-4bcf31691a36

About this result

Related concepts (32)

Stellar corona

A corona ( coronas or coronae) is the outermost layer of a star's atmosphere. It consists of plasma. The Sun's corona lies above the chromosphere and extends millions of kilometres into outer space. It is most easily seen during a total solar eclipse, but it is also observable with a coronagraph. Spectroscopic measurements indicate strong ionization in the corona and a plasma temperature in excess of 1 000 000 kelvins, much hotter than the surface of the Sun, known as the photosphere. Corona is, in turn, derived .

Solar wind

The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between 0.5keV. The composition of the solar wind plasma also includes a mixture of materials found in the solar plasma: trace amounts of heavy ions and atomic nuclei of elements such as C, N, O, Ne, Mg, Si, S, and Fe. There are also rarer traces of some other nuclei and isotopes such as P, Ti, Cr, 54Fe and 56Fe, and 58Ni, 60Ni, and 62Ni.

Coronal mass ejection

A coronal mass ejection (CME) is a significant ejection of magnetic field and accompanying plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established. If a CME enters interplanetary space, it is referred to as an interplanetary coronal mass ejection (ICME).