Abstract:

Abstract:

Abstract:Since it is important to judge the metal bridge wire completely detonated whether or not in the metal bridge wire explosion experiment, a method was proposed to judge the detonation state of the bridge wire by the electromagnetic pulse radiation effect. The electromagnetic pulse signal of the metal bridge wire during the detonation process was measured by the antenna, while the measured electromagnetic pulse signal was analyzed to judge the bridge wire detonation status. The electromagnetic pulse signal shows that the electromagnetic pulse generated by the complete detonation and the incomplete detonation state, has a significant difference in duration and radiation spectrum. When the bridge wire is completely detonated, the electromagnetic signal duration in the intrinsic explosion phase is short, and the electromagnetic signal generated in the plasma phase lasts long. The electromagnetic pulse signal includes high frequency electromagnetic radiation of 90 MHz to 100 MHz. When the bridge wire is not completely detonated, the electromagnetic signal generated during the intrinsic explosion phase lasts for a long time, while the electromagnetic signal generated during the plasma phase has a short duration. The frequency of the electromagnetic pulse signal is mainly concentrated in the low frequency region below 40 MHz.

Abstract:Electrical explosion of the thin golden wire is fundamental for the EBW detonator. In this paper, the expansion process of plasma generated in 0.04 mm wire explosion was captured using interferometry diagnostic. Moreover, the transient current during the electrical explosion was also measured in order to establish the connection between current and plasma expansion in time domain using a photoelectric transducer. 3D dynamic simulation of plasma expansion was conducted, in which JWL equation of state containing energy term was selected to describe the dynamic behavior of plasma. The results shows the simulation result was in good agreement with experimental results. And under the condition of 0.22 μF capacitor and 3900 V charging voltage, the expansion velocity of plasma reaches 8913 m·s^-1,and then 3000-4000 m·s^-1 after travelling for 1.63 mm. The pressure of plasma is higher than 2.4 GPa. The satisfactory agreement between simulation and experiment indicates that the JWL equation of state is suitable for plasma generated in electrical explosion. The simulation results show that the change of the pressure and density of plasma with travelling distance could be described using polynomial function. The result in this paper was able to give more insight of the mechanism of EBW detonator and thus provide suggestions for the design of the EBW detonator.

Abstract:Using microelectromechanical system (MEMS) technologies including magnetron sputtering, ultraviolet lithography and chemical vapor deposition, two kinds of high-voltage switches based on Schottky diode and p-n diode were designed and fabricated. Electrical characterizations were performed to investigate their performances under no-load condition, which showed that the current peaks of the two switches reached up to about 2000 A at 0.22 μF/1500 V and 0.22 μF/1200 V, respectively. The influence of trigger capacitor, trigger voltage, main voltage, dielectric film thickness and bi-diode structure on the conduction performance of single shot switch was studied. It is revealed that the minimum trigger voltage decreased gradually with the increase of capacitance. Reducing the thickness of dielectric film, increasing the trigger voltage and main voltage are all beneficial to improve the current peak. Besides, bi-diode structure can also improve the current peak. Finally, according to the electrical curves of single shot switch, its action process can be divided into three stages, namely the electro-explosion of diode, the breakdown of dielectric film and the rise of pulse current. The conduction mechanism and resistance model of single shot switch were also established. The results indicate that the resistance of single shot switch is very low, almost negligible.

Abstract:To explore the exploding mechanism of composite multilayers, the properties of Ni/Cu multilayer exploding foil were studied. Ni/Cu composite multilayers (modulation period 200 nm/300 nm and 300 nm/400 nm, respectively), pure Cu and Ni films with the same thickness were prepared by electrochemical deposition. The plasma emission spectroscopy was measured. Under different discharge current conditions, the electron temperature of electrically exploded plasma of Ni/Cu composite multilayers with different structures, pure Cu and Ni films was calculated, respectively. After matching barrels and flyers with exploding foils, the velocity of flyer driven by different exploding foils was measured by PDV method. The performance of the exploding foils driving flyer under different discharge current conditions were obtained. The results show the plasma emission spectroscopy intensity and electron temperature of (Ni₂₀₀Cu₃₀₀)₈ and (Ni₃₀₀Cu₄₀₀)₅Ni₃₀₀ is higher than pure Cu and Ni at discharge current of 2.5 kA, indicating the Ni/Cu composites have higher electrically exploding energy density at the same condition. The Ni in Ni/Cu composites promotes the plasma to push flyer forward, resulting in the accelerating time and final velocity of flyer driven by (Ni₂₀₀Cu₃₀₀)₈ and (Ni₃₀₀Cu₄₀₀)₅Ni₃₀₀ are both higher than those of flyer driven by pure Cu.

Abstract:Low⁃temperature co⁃fired ceramic (LTCC) technology was employed to realize the integrated fabrication of exploding foil initiation chip. 5 μm thick Au bridge foil (300 μm×300 μm) was prepared by screen printing,using raw porcelain sheets of 25 μm and 50 μm thickness as the flyers for the chip. Two kinds of chips with the barrel shape of circular (Φ=400 μm) and square (L×W=300 μm×300 μm) were obtained. The electrical explosion characteristics of Au bridge foil were studied under the discharge of 0.22 μF capacitor. The velocity characteristics of the ceramic flyer and its morphology in motion process were analyzed by photon Doppler velocimetry. Results show that the maximum energy utilization rate of Au bridge foil at 1.8 kV, and the final speed of flyer increases with the increase of the firing voltage. Besides, the outlet velocity of flyer in square barrel is 106-313 m·s^-1,which is higher than that in circular barrel at the same firing condition. In addition, the thicker of the ceramic flyer, the more complete it will be during the course of flying. The exploding foil initiation chip prepared by the LTCC technology can successfully detonate the HNS explosive and ignite the BPN ignition powder. The minimum detonation voltage and minimum ignition voltage of LTCC exploding foil initiation chip (50 μm thick ceramic flyer, circular barrel) are 2.5 kV and 1.4 kV, respectively.