For metallized film capacitors (MFCs), the pulsed current would lead to the electrode fracture, the process might be accelerated under the repetitive pulsed current, and finally leading to the failure of MFCs. In order to study the mechanism of electrode fracture and its influencing factors, an experiment platform based on metallized film is established to observe electrode fracture by using a microscope. The experimental results show that for electrode fracture of metallized film, the threshold current density (TCD) is $2.20 \times 10^{10}$ A/m² when the period is 310 $\mu \text{s}$ and the reverse factor is 10%. Theoretical results are also derived based on the analysis of electromagnetic force and Joule heat. The results indicate that, the fracture development is caused by the melting process of the electrode, together with the liquid metal flow driving by the electromagnetic force under the effect of multiple current pulses. Neither the electromagnetic force individually nor the direct vaporization would cause the fracture to develop. With respect to current distortion and heat conversion efficiency, the calculated peak current density is $j_{\mathrm {max}} = 2.17 \times 10^{10}$ A/m², which agrees with the TCD in the experiment. Thinner electrode has a larger TCD, when $d_{m}$ decreases from 20 to 4 nm; TCD increases from $1.07 \times 10^{10}$ to $2.25 \times 10^{10}$ A/m².

中文翻译：

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多脉冲电流下金属化薄膜的阈值电流密度

对于金属化薄膜电容器（MFC），脉冲电流会导致电极断裂，在重复脉冲电流的作用下，该过程可能会加速，最终导致 MFC 失效。为研究电极断裂的机理及其影响因素，建立了基于金属化薄膜的实验平台，利用显微镜观察电极断裂。实验结果表明，对于金属化薄膜的电极断裂，阈值电流密度（TCD）为 $2.20 \times 10^{10}$ 周期为 310 时的A/m ² $\mu \text{s}$ 反向系数为 10%。理论结果也是基于对电磁力和焦耳热的分析得出的。结果表明，断裂的发展是由电极的熔化过程以及在多个电流脉冲的作用下由电磁力驱动的液态金属流动引起的。单独的电磁力和直接汽化都不会导致裂缝发展。关于电流畸变和热转换效率，计算的峰值电流密度为 $j_{\mathrm {max}} = 2.17 \times 10^{10}$ A/m ²，与实验中的TCD一致。较薄的电极具有较大的 TCD，当 $d_{m}$ 从 20 纳米减少到 4 纳米；TCD 从 $1.07 \times 10^{10}$ 至 $2.25 \times 10^{10}$ A/米²。