氩气中铝丝电爆炸空间形态不均匀现象及其抑制方法

Spatial Inhomogeneities of Electrically Exploding Aluminum Wires in Argon Gas and Its Suppression Methods

铝丝电爆炸法制备纳米粉体具有低成本、高效率、产物纯度高且粒度分布可控等优势,其扩散阶段空间形态均匀性是影响纳米铝粉品质的关键因素。为此设计并搭建了铝丝电爆炸实验系统,可实现包括激光成像、分幅成像与辐射光谱分析的超快光学诊断。观测到铝丝电爆炸扩散阶段出现的等离子体晕层、“纺锤形”结构、“拉链状”结构、分层结构、局部热点、缺口、残留丝核等空间形态不均匀现象,并揭示了其产生原因包括氛围气体放电、径向非均匀汽化、热力学不稳定性、磁流体力学不稳定性。建立了基于自辐射图像的空间形态均匀性量化表征方法与判别准则。研究获得了气压与电流参数对阻性阶段及沉积能量特性的影响规律,并提出了空间形态不均匀性的抑制方法——增加气压与提高电流上升率,最终确定了可实现均匀电爆炸的参数选取方法。

Electrically exploding wires(EEW)for nanoparticle preparation has advantages of being low cost,high efficiency,providing high purity,and allowing for controllable size distribution.However,spatial homogeneities in the EEW diffusion stage is a critical influence factor of the quality of nanoparticles.In this paper,an experimental system was designed and constructed to investigate EEW,and the ultrafast optical diagnoses,including laser imaging,multi-frame photography,and emission spectrum analysis,could be realized.Various spatial inhomogeneities,including coronal plasma,spindle structures,zipper-like structures,stratification structures,local hot spots,gaps,and residual cores,were observed.The causes of these inhomogeneities were summarized as follows:atmospheric discharge,radial inhomogeneous vaporization,thermal instability,and magnetohydrodynamic instability.A quantification method and the criteria of spatial homogeneity were established based on photographs.The effects of ambient pressure and current parameter on resistive stage and energy deposition were obtained.Moreover,the suppression methods of spatial inhomogeneities were proposed,including increasing ambient pressure and current rise rate.Ultimately,the parameter selection method for homogeneous EEW was determined.