Reconstruction of plasma density profiles by measuring spectra of radiation emitted from oscillating plasma dipoles

Abstract

We suggest a new method for characterising non-uniform density distributions of plasma by measuring the spectra of radiation emitted from a localised plasma dipole oscillator excited by colliding electromagnetic pulses. The density distribution can be determined by scanning the collision point in space. Two-dimensional particle-in-cell simulations demonstrate the reconstruction of linear and nonlinear density profiles corresponding to laser-produced plasma. The method can be applied to a wide range of plasma, including fusion and low temperature plasmas. It overcomes many of the disadvantages of existing methods that only yield average densities along the path of probe pulses, such as interferometry and spectroscopy.

Exact analytical calculation and numerical modelling by finite-difference time-domain method of the transient transmission of electromagnetic waves through cold plasmas

“…Of course, thermal effects and collisions are very important for the processes near ω pl . However, sometimes they can be left in the background (Kylychbekov et al 2020). Here, the transient propagation at ω = ω pl is studied as a limit case of the developed cold collisionless model.…”

“…Here the second term describes a Langmuir oscillation (or plasma oscillation) (Krall & Trivelpiece 1973, § 4.2), (Chen 2012, § 4.3) with zero wavenumber in the limit t → ∞ and the third term corrects it at intermediate time. Usually a Langmuir oscillation with zero wavenumber is called a plasma dipole oscillation (Kylychbekov et al 2020) because there is no fluctuation of the plasma density in this case. But it is an electrostatic oscillation since there is no fluctuating magnetic field.…”