Large-scale ion generation for precipitation of atmospheric aerosols

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.

Deposition of charged aerosols by E × B enhanced low‐temperature plasma jet array

“…The measurement by aerosol spectrometer suggested the total aerosol density (diameter: 0.25–10 μm) was 1.5 × 10 9 /m 3 at the humidity of 50%, which was much lower than the ion density (15.8 × 10 12 –1.5 × 10 12 /m 3 ) shown in Figure 8, therefore, aerosols had ample opportunities to be charged. [ 15,19,35 ] The diffusion of ions to aerosols’ surface facilitated the charging of aerosols, so lots of aerosols were charged through the diffusion charging mechanism. Different from the neutral aerosols, which can only collide with each other through the thermophoretic and diffusionphoretic forces, the charged aerosols can induce the image charges in adjacent neutral aerosols, and the consequent image charge forces were the short‐range attractive and long‐range repulsive charge.…”

“…More ions generated by E × B enhancement (Figure 8）and the subsequent higher collision rate between charged aerosols and neutral aerosols resulted in a faster increase in aerosol density (larger than 1 μm), as shown in Figure 10d. [ 8,15,36,37 ]…”

“…Once aerosols passed through this volume, lots of charged aerosols were produced. [ 15 ] The cost of system hardware of this large‐scale corona system was 0.3 million CNY, and the operating cost was only 5 CNY/h. [ 15 ] However, the budget for the implementation of artificial rainfall enhancement in Shanghai, China, suggests that the implementation of artificial rainfall enhancement required 4.7 million CNY, of which 0.4 million CNY was required for AgI catalysts that directly act on clouds.…”

“…[ 15 ] The cost of system hardware of this large‐scale corona system was 0.3 million CNY, and the operating cost was only 5 CNY/h. [ 15 ] However, the budget for the implementation of artificial rainfall enhancement in Shanghai, China, suggests that the implementation of artificial rainfall enhancement required 4.7 million CNY, of which 0.4 million CNY was required for AgI catalysts that directly act on clouds. [ 16 ] A rainfall enhancement trial based on a ground‐based corona discharge system was conducted on the Hajar Mountains for 170 days in 2013.…”

Enhanced transmembrane transport of reactive oxygen species by electroporation effect of plasma

“…Plasma sources can generate electric fields, with the intensity ranging from a few to 100 kV/cm, [ 8–15 ] which play an important role in the interactions between plasma and cells. [ 16–19 ] Electroporation happened when cells are exposed to the strong electric field of plasma, leading to the increase in cell membrane permeability and the appearance of hydrophilic pores.…”