Microphysical Effects of Water Content and Temperature on the Triboelectrification of Volcanic Ash on Long Time Scales
Microphysical Effects of Water Content and Temperature on the Triboelectrification of Volcanic Ash on Long Time Scales
复制标题
DOI：
10.1029/2019jd031498
复制
发表时间：
2019-08
期刊：
影响因子：
--
通讯作者：
Joshua Méndez Harper-Joshua-Méndez Harper-2126679743;L. Courtland;J. Dufek;J. McAdams
中科院分区：
文献类型：
--
作者：
Joshua Méndez Harper-Joshua-Méndez Harper-2126679743;L. Courtland;J. Dufek;J. McAdams
水和温度对颗粒材料摩擦起电的影响已被许多作者报道，但尚未在火山羽流的背景下进行有力的研究。在这里，我们提出了一组实验的结果，旨在阐明环境条件如何调制对流柱上部区域的火山灰的摩擦电特性。我们发现，少量的水可以减少亚毫米大小的灰粒收集的电荷高达一个数量级。在恒定的相对湿度下增加温度似乎也会减少颗粒获得的电荷量。对我们数据的分析表明，如果粒子在潮湿环境中在分钟长的时间尺度下进行低能、低频碰撞，电荷耗散将超过电荷积累。因此，我们的工作表明，摩擦带电可能是气体推力区域之外的一种低效的起电机制，在该区域中，碰撞能量和速率很高，停留时间很短。
The effects of water and temperature on the triboelectrification of granular materials have been reported by numerous authors, but have not been studied robustly in the context of volcanic plumes. Here, we present the results of a set of experiments designed to elucidate how environmental conditions modulate the triboelectric characteristics of volcanic ash in the upper region of the convective column. We find that small amounts of water can reduce the charge collected by submillimeter‐sized ash grains by up to an order of magnitude. Increasing temperature at a constant relative humidity also appears to decrease the amount of charge gained by particles. Analysis of our data shows that if particles undergo low‐energy, low‐frequency collisions in humid environments under minute‐long time scales, charge dissipation dominates over charge accumulation. Thus, our work suggests that triboelectric charging may be an inefficient electrification mechanism outside of the gas‐thrust region where collision energies and rates are high and residence times are low.