A New Technique for Investigating Dust Charging in the PMSE Source Region

Abstract

A new technique for investigating dust charging in the PMSE (polar mesospheric summer echoes) source region is proposed and discussed in this paper. The first high-frequency (HF) modulation of the PMSE with varying pump power was employed during a recent experimental campaign at EISCAT (European Incoherent Scatter Scientific Association). Two experiment setups including HF pump power stepping as well as quasi-continuous power sweeping were used. The experiment was designed based on a computational model capable of simulation of PMSE evolution during HF pump modulation in order to develop a new approach for studying the dust charging process in the PMSE source region. The charge state of dust particles along with background dusty plasma parameters is estimated using the experimental and computational results. A detailed future experimental design based on background dusty-plasma parameters is proposed. where irreg , K, T i , m i , in , Z d0 , n d0 , n e0 , r d , v te0 , , and r h denote electron density fluctuation wavelength, Boltzmann constant, ion temperature, ion mass, ion neutral collision frequency, dust charge number, dust number density, electron number density, dust radius, electron thermal velocity, equilibrium normalized dust floating potential, and heating ratio (T e /T i), respectively. As shown in Equations 1 and 2, both processes depend on electron temperature (T e); therefore, radio modulation of PMSE will modify the two processes (Scales & Mahmoudian, 2016). Background dusty plasma parameters also play a role in the diffusion and charging timescales. The diffusion process is proportional to RESEARCH LETTER

Global Simulations of Multi‐Frequency HF Signal Absorption for Direct Observation of Middle Atmosphere Temperature and Composition

“…Heating of the ionospheric plasma by modulated HF waves leads to physical processes with a wide range of scales due to an elevated T e / T i (electron to ion temperature). Artificial modulation of the D‐region plasma to diagnose dusty plasma associated with polar mesospheric summer echoes has been an area of research over the past two decades (Havnes, 2004; Mahmoudian et al., 2020; Scales, 2004; Scales & Mahmoudian, 2016). Polar mesospheric summer echoes (PMSE) are strong radar echoes associated with polar mesospheric clouds, which are natural ice/dust layers in the polar region in the altitude range of 80–90 km and are widely believed to be a direct manifestation of global warming.…”

“…past two decades (Havnes, 2004;Mahmoudian et al, 2020;Scales, 2004;Scales & Mahmoudian, 2016). Polar mesospheric summer echoes (PMSE) are strong radar echoes associated with polar mesospheric clouds, which are natural ice/dust layers in the polar region in the altitude range of 80-90 km and are widely believed to be a direct manifestation of global warming.…”