Experimental And Theoretical Study Of Pulse Generator Based On Shock Wave Demagnetization Of Nd₂Fe₁₄B

Phenomenon of shock wave demagnetization and principle of electromagneticinduction have been used to design demagnetization generator. Because of advantages ofsmall volume, high output, simple design and so on, demagnetization generator hasextensive application prospect in the weapon system. In this thesis, combining theoreticalmethod, experimental method and numerical simulation method, Nd2Fe14B magnetdemagnetization rule at low shock wave pressure, induced electromotive force and currentsof demagnetization generator were analyzed.The shock wavedemagnetization generator was designed by light gas gun driven flyer.Induced electromotive forces of demagnetization generator were tested. Magnetdemagnetization rate curve of change over time were calculated. The results showed thatwith the increase of the speed of flyer, induced electromotive force peak will also increase,the higher the speed of flyer, the smaller the gains; When speed of copper flyer increasedfrom200m/s to410m/s, Nd2Fe14B magnet demagnetization rate will also increase from0.358to0.918.Changes of magnet internal shock wave pressure with the time were numericallycalculated by LS-DYNA. The results showed that, in the process of loading of flyer, strongsparse wave also affected magnet after high pressure shock wave; The critical pressure ofserious demagnetization of Nd2Fe14B should be between4~7GPa.Cylindrical Nd2Fe14B magnet space magnetic field was equivalently replaced bytubular circular current space magnetic field. Induced electromotive force ofdemagnetization generator was calculated. Current output of demagnetization generatorcalculation formula was deduced. The currents output under different loads were calculated.The influences of the coil number of turns on the current output were analyzed. The resultsshowed that the tubular circular current space magnetic field can replace cylindricalNd2Fe14B magnet space magnetic field equivalently.