Large-scale ion generation for precipitation of atmospheric aerosols

Shaoxiang Ma,Kostya Ostrikov,Maoyuan Xu,He Cheng,Dawei Liu,Jiacheng Li

doi:10.5194/acp-20-11717-2020

Abstract

Abstract. Artificial rain is explored as a remedy for climate change caused farmland drought and bushfires. Increasing the ion density in the open air is an efficient way to generate charged nuclei from atmospheric aerosols and induce precipitation or eliminate fog. Here we report on the development of a large commercial-installation-scale atmospheric ion generator based on corona plasma discharges, experimental monitoring, and numerical modeling of the parameters and range of the atmospheric ions, as well as the application of the generated ions to produce charged aerosols and induce precipitation at the scale of a large cloud chamber. The coverage area of the ions generated by the large corona discharge installation with the 7.2 km long wire electrode and applied voltage of −90 kV is studied under prevailing weather conditions including wind direction and speed. By synergizing over 300 000 localized corona discharge points, we demonstrate a substantial decrease in the decay of ions compared to a single corona discharge point in the open air, leading to large-scale (30 m ×23 m ×90 m) ion coverage. Once aerosols combine with the generated ions, charged nuclei are produced. Higher wind speed has led to larger areas covered by the plasma-generated ions. The cloud chamber experiments (relative humidity 130±10 %) suggest that charged aerosols generated by ions with a density of ∼104 cm−3 can accelerate the settlement of moisture by 38 %. These results are promising for the development of large-scale installations for the effective localized control of atmospheric phenomena.

Highlights

The water cycle and rainfall on the Earth are affected by climate change, causing widespread droughts around the world (Dai, 2013; Trenberth et al, 2014)
A large-scale corona plasma discharge system was installed to analyze the production and coverage area of negative ions that are capable of inducing the precipitation of atmospheric aerosols in the downwind direction
The coverage area of the ions was dramatically improved by using over 300 000 corona discharge points, which reduced the common destructive interference leading to the decay of ion concentrations in the open air, thereby dramatically increasing the outward ion transport capacity of the large-scale corona plasma discharge installation

Summary

Introduction

The water cycle and rainfall on the Earth are affected by climate change, causing widespread droughts around the world (Dai, 2013; Trenberth et al, 2014). Nielsen et al (2011) found that charged nuclei could remain in the condensation phase even when the relative humidity is less than 100 % (Nielsen et al, 2011). This is why plasmaand laser-based techniques have been employed to generate charged nuclei in the open air to try to realize rain enhancement or, alternatively, fog elimination (Henin et al, 2009; Khain et al, 2004; Tan et al, 2016)

Methods

Results

Conclusion