Understanding the nanoparticle formation during electrical wire explosion using a modified moment model

Electrical explosion of wires (EEW) was carried out in an argon atmosphere for the preparation of nanoparticles. Aluminium wires with 0.1 mm diameter and 13 cm length (low mass) and 0.4 mm diameter and 11 cm length (high mass) were used, for which the vaporization energy of the wire was, respectively, far below and comparable to the initial stored energy of the power-supply capacitors. A numerical model was used to study the nanoparticle formation within the exploding wire plasmas. The model is based on a moment method and was modified according to the specific requirements of EEW—rapid expansion of the exploding wire and a high concentration of monomers—to take into consideration the quenching due to mechanical work on the surrounding medium, the energy release during the vapour–liquid phase transition, and the coagulation of liquid particles. The calculation took initial and boundary values from the experimental results and predicted average particle diameters of 36 nm and 116 nm for the low mass and high mass wire respectively, which are in qualitative agreement with the experimental values of 33 nm and 103 nm obtained from SEM images. The nucleation mechanisms including homogeneous nucleation and ion-induced nucleation are discussed in detail; the importance of including the phase transition and coagulation is demonstrated. (paper)