RESEARCH ON ELECTROMAGNETIC RADIATION DURING THE EXPLOSION PROGRESS OF COMPOSITION B EXPLOSIVES$^{bf 1)}$

The electromagnetic radiation interference, which can be obviously observed during the explosives process, has attracted attention in many fields. However, the corresponding generation mechanism and theoretical model are still immature, experiments are still the key approach to study this phenomenon. This paper designs experiments to collect the electromagnetic radiation signals, generated by different charges of composition B explosives (Comp B), and uses the wavelet transform method to obtain these signals time-frequency characteristics, namely the main spectrum distribution is in the range of 0$sim$50 kHz. Furthermore, the self-developed EXPOSION-3D software is used to simulate the experimental conditions to obtain the characteristics of the flow field during the explosion. By comparing the experimental results with the numerical simulations, series of conclusions are given in the following. The first pulse signal is the electromagnetic pulse directly generated by the high-temperature and high-pressure plasma generated by the detonation of Comp B; the second pulse signal is an electromagnetic pulse generated by the plasma formed at the air shock wave front which is caught up by the reflected shock wave from the ground; the third pulse signal is an invalid signal caused by the shock wave hitting the measurement coils. The amplitude of the first electromagnetic pulse has a linear relationship with the 1/3 power of the charge, and its arrival time is not sensitive to the charge of explosive. The time of the second electromagnetic pulse is in an exponential relationship with the charge of explosive. Overall, this paper put forward the characteristics of the explosion wave flow field when the shock wave reflection forms the electromagnetic wave signal, which provides verification data for the subsequent theoretical research.