RUDN University scientist suggested a simple model of dense plasma spectral properties

October 08, 2020

A scientist from RUDN University suggested a new physical model to describe the optical properties of dense plasma. The model was tested on available experimental data and does not require complex calculations. The work was published in the Annals of Physics journal.

Plasma is the fourth state of matter, along with solid matter, liquid, and gas. High-density (up to ~1 g/cm3) plasma is used in many technical and experimental installations such as heavy-current electrical discharge devices, control fusion targets, or laser targets that are used to study the properties of matter under extreme pressure.

An important feature of plasma is its light absorptance coefficient. Its value is to a great extent dependent on the photo effect (the transfer of energy from the photons to the electrons of a substance) and light absorptance in optical lines. Both of these processes, in turn, are due to the so-called microfield--an electric field inside plasma produced by the chaotic thermal movement of ions and free electrons. This field can fluctuate from its average value in time and space, and knowing its characteristics is important for solving numerous scientific and technical tasks.

"We have analyzed all models described in scientific literature and identified their disadvantages. Namely, these models provide for the infinite density of the electric field energy in an atomic cell which contradicts the laws of physics. The only model that doesn't have these disadvantages is the Quasi Independent Particle model or QUIP. We developed a generalized version of this model that takes into account the inhomogeneity of plasma microfield. This helped us extrapolate the model to high-density plasma for which homogeneous microfield approximations cannot be used. The generalized QUIP model is very simple and does not require complex calculations, because all formulas are presented in an explicit manner," said Alexander Belov, a Candidate of Physics and Mathematics and a senior lecturer at the Department of Applied Informatics and Probability Theory, RUDN University.

To confirm a theoretical model, one has to test it against experimental results. For this purpose, the team chose experiments on the fluorescence of laser-based plasma that have been going on since the 1980s. In these experiments, tiny glass bubbles were filled with a mix of deuterium, argon, krypton, neon, and other gases, covered with aluminum coating and then heated with a powerful multi-beam laser system. As a result, plasma with high temperature and density was formed inside the bubbles and emitted a series of lines in the X-ray range.

"The number of observable spectral lines can be theoretically predicted by a model. In the majority of works, this parameter was neither calculated nor compared to experimental data. Our analysis shows that all models except for QUIP gave wrong predictions that did not match experimental results. Therefore, our model is better at describing the experiment. This test is a convincing proof of the advantage that the generalized QUIP model has over other known models," added Alexander Belov.

Description of heterogeneous plasma microfield and optical properties of plasma by the QUIP model

RUDN University

Related Plasma Articles from Brightsurf:

Plasma treatments quickly kill coronavirus on surfaces
Researchers from UCLA believe using plasma could promise a significant breakthrough in the fight against the spread of COVID-19.

Fighting pandemics with plasma
Scientists have long known that ionized gases can kill pathogenic bacteria, viruses, and some fungi.

Topological waves may help in understanding plasma systems
A research team has predicted the presence of 'topologically protected' electromagnetic waves that propagate on the surface of plasmas, which may help in designing new plasma systems like fusion reactors.

Plasma electrons can be used to produce metallic films
Computers, mobile phones and all other electronic devices contain thousands of transistors, linked together by thin films of metal.

Plasma-driven biocatalysis
Compared with traditional chemical methods, enzyme catalysis has numerous advantages.

How bacteria protect themselves from plasma treatment
Considering the ever-growing percentage of bacteria that are resistant to antibiotics, interest in medical use of plasma is increasing.

A breakthrough in the study of laser/plasma interactions
Researchers from Lawrence Berkeley National Laboratory and CEA Saclay have developed a particle-in-cell simulation tool that is enabling cutting-edge simulations of laser/plasma coupling mechanisms.

Researchers turn liquid metal into a plasma
For the first time, researchers at the University of Rochester's Laboratory for Laser Energetics (LLE) have found a way to turn a liquid metal into a plasma and to observe the temperature where a liquid under high-density conditions crosses over to a plasma state.

How black holes power plasma jets
Cosmic robbery powers the jets streaming from a black hole, new simulations reveal.

Give it the plasma treatment: strong adhesion without adhesives
A Japanese research team at Osaka University used plasma treatment to make fluoropolymers and silicone resin adhere without any adhesives.

Read More: Plasma News and Plasma Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to