Influence of barrel diameter on exploding foil initiators

Exploding foil initiators (EFIs) offer several safety and timing advantages over other means of initiating high explosives. In order to increase the knowledge about the barrel diameter on sensitivity of HNS-IV, several samples with different barrel diameter were investigated. Mean threshold voltage, and flyer velocity were measured and compared. Meanwhile, we present the flyer images with restricted condition of EFIs during flight by X-ray phase contrast imaging system at the 45 TW laser facility at China Academy of Engineering Physics. The barrel diameter has a related to mean threshold voltage of EFIs. The lowest mean threshold voltage is 2830 V with 0.4 mm barrel diameter. The mean threshold voltage is increased by about 54 % as the barrel diameter decreases from 0.4 mm to 0.2 mm. But the decreased barrel diameter significantly increased the flyer velocity. The dynamic flyer image gives the evidence to prove that the impacting width of flyer is the key parameter of EFIs. The impacting width of flyer is related to barrel diameter. Meanwhile, the curvature of the flyer is related to barrel diameter and exploding foil width. This fundamental understanding has led to increased knowledge on the mechanism of EFIs and has allowed us to improve our predictive capability through modeling.