Electrical Conductivity Analysis of Volcanic Ash and Particle Shape data

In part, this study seeks to understand the influence of particle shape on the electrical conductivity of volcanic ash. Grain conductivity values were calculated by applying spherical, oblate (flattened spheroids), and prolate (elongated spheroids) ellipsoidal morphological parameters within a general effective media (GEM) equation to understand the impact of particle shape on the calculated grain conductivity. These equations require an average aspect ratio value for the eight volcanic ash samples analyzed in the study. This dataset contains the measured aspect ratio values of the milled samples and Alaska samples of 1000 randomly selected grains that presented a flat face optimal for shape and size measurements to get a representative sampling. Values were determined from backscatter electron images (BSE) from a scanning electron microscope (SEM). Shapes were analyzed using images freeware. This dataset also contains grain conductivity calculations for the three morphological parameters using an averaged aspect ratio value. Results show that values remain within the same order of magnitude between the morphological equations. However, the volume conductivity values are all lower than the grain conductivities using a spherical, prolate, and oblate shape assumption. It was determined that particle shape have a limited effect on grain conductivities. However, aspect ratio is not a very sensitive parameter to quantify grain shapes, so more analysis is needed to fully understand the relationship between electrical conductivity of volcanic ash and particle shape.本研究部分旨在探究颗粒形貌对火山灰电导率的影响。研究中，将球形、扁球形（压扁椭球）与长球形（伸长椭球）的椭球形貌参数代入广义有效介质（GEM）方程，计算得到颗粒电导率数值，以此分析颗粒形貌对计算所得颗粒电导率的影响。上述方程需采用本研究中分析的8个火山灰样品的平均长径比数值。本数据集包含研磨样品与阿拉斯加样品的实测长径比数据，共选取1000颗具有平整表面、适宜形貌与尺寸测量的颗粒以保证采样的代表性。相关数值通过扫描电子显微镜（SEM）的背散射电子图像（BSE）测得，形貌分析采用免费图像软件完成。本数据集还包含基于平均长径比，针对三种形貌参数计算得到的颗粒电导率结果。研究结果显示，不同形貌方程计算得到的电导率数值处于同一数量级。然而，基于球形、长球形与扁球形假设得到的体积电导率，均低于颗粒电导率。研究表明，颗粒形貌对颗粒电导率的影响有限。但由于长径比并非量化颗粒形貌的灵敏参数，因此需开展更多分析以全面厘清火山灰电导率与颗粒形貌之间的关联。