Arc-surface discharge testing and electrothermal modeling for the electrostatic threshold of energetic materials

Electrostatic discharge (ESD) sensitivity serves as the primary measure for evaluating the electrostatic hazards of energetic materials. While needle electrodes are commonly employed in standard sensitivity testing, sharp tips are deliberately avoided in practical production settings. This study utilizes an ESD test system configured with two metal arc-surface electrodes. The minimum ignition energy (MIE) values obtained for RDX, HMX, and AP under arc-surface discharge range from 744 to 1089 mJ, which are significantly greater than for needle electrodes (55–300 mJ). This finding confirms that eliminating sharp protrusions effectively reduces the risks associated with electrostatic discharge. Current simulation approaches for electrostatic spark development typically apply an electrostatic field model to determine discharge occurrence and a thermal model to assess material ignition under heating. These methods, however, are incapable of predicting the MIE or capturing the evolution of dielectric properties during the breakdown process. To address this limitation, an electrothermal field model is established that reproduces the complete sequence from applied voltage to material ignition. The model integrates the phase-field method to simulate spark propagation and the variation of air dielectric properties during breakdown, incorporates Joule heating to convert electrostatic energy into a thermal source, and employs the Arrhenius equation to evaluate the onset of chemical reactions. Simulated results for ESD voltage, ESD heat, and ignition voltage exhibit good agreement with experimental measurements, thereby validating the reliability of the model. Moreover, the framework can be extended to analyze sensitivity under diverse conditions by adjusting external parameters such as electrode gap and intrinsic material properties including relative permittivity.