A new approach to enhance the output power of an HMFCG

Abstract

Helical magnetic flux compression generators (HMFCG) driven by high explosive are widely used in a variety of high- energy and high current applications, especially in a single shot at remote location applications. General principles of HMFCG are reasonably well documented, R&D of an HMFCG has been got a great achievement. However the desire to design an HMFCG with a higher efficiency is still being remained by most of research groups even now. As it is well known, the performance of a high gain HMFCG is dependent on the balance between magnetic pressure and detonation pressure, while the detonation pressure is decreased with the flux compression process. In order to utilize the finite detonation pressure, it is proposed that a object with proper position and weight is placed at the rear part inside the armature to reflect the detonation wave and to enhance the effective detonation pressure in the radial direction. In this paper firstly it is analyzed that whether the reflection boundary (or fixed-wall) can be used in an real HMFCG device with a special barrier object, then the influence of a fixed wall object on the process of magnetic flux compression in a flux trapping two staged HMFCG is analyzed systematically by using code MFCG-IV, which is a two-dimensional magnetic hydrodynamic (MHD) code used to model the dynamic behavior of magnetic flux compression generators with helically wound coils. Simulation results show that output power of an HMFCG can be enhanced from the reflection of the detonation wave by the proper designed 'fixed wall' object in the end part of the armature. A series of models have been simulated and analyzed. It is found that the amplitude and its time variation of the output current are affected by the location of the fixed wall objects, generally over 20% output power of an HMFCG can be enhanced by using this approach.