Investigation Of Electromagnetic Pulse Radiation From Electro-explosive Opening Switches

Electro-explosive opening switch (EEOS) is one of the most common utilized switches for high-voltage pulse accelerators. Until now it has still been widespread in the field of high-power microwave due to some properties, such as the low cost, simple structure, easy to fabricate, quite short time for switching off, and controllable conduction time depending on conduction materials, conduction dimensions, and ambient dielectics. However, when the current in a circuit reaches its maximum value an EEOS is switched off and, simultaneously, intense electromagnetic pulse radiation appears, which often destroys electronic components in some distance. Recent researches are focused on the high-voltage resistance and fast switch of EEOSes, however, such intense radiation from EEOS is neglected. This thesis presented experimental investigations and discussed the nature behind this phenomenon.The experimental investigations on the EEOS were conducted with the Tomachantest bed. A whip antenna and an annular antenna were, respectively, utilized to measureelectromagnetic pulse radiation. It was found that the radiation frequency varied in therange of 30～150 MHz, i.e., low frequency electromagnetic pulse radiation with a widespectrum was emitted from the EEOS. The phenomena do not only exist in EEOScavity filled with SF₆ ,but also exist when the ambient gas is changed to N₂. It is acharacter from EEOSes. In coaxial cable experiments, the waveforms for the radiationfield in space and the current on the cable were identical to each other. Additionally, themaximum current reached 217 mA and the maximum field intensity close to the cablewas 1740 V/m, indicating an electromagnetic pulse radiation with a large field intensity.The mechanism of generating electromagnetic pulse radiation was discussed basedon the physical process of EEOS switch. According to the experimental curves forEEOS and electrodynamic formulas, the electromagnetic pulse radiation from EEOSwas theorectically analysed and the corresponding conclusions are listed as follows.Electromagnetic pulse radiation occurred as the current hopped, that is, the simultaneityof Electromagnetic pulse radiation and current hopping was observed. Furthermore, theElectromagnetic pulse radiation intensity was proportional to the changing ratio ofEEOS current And frequencies of the radiation field and the changing ratio of EEOScurrent should be identical to each other. Generally, the process of EEOS switchinggoes with the formation of plasma. We qualitatively anafysed the current fluctuation asthe EEOS switched off based on the Z-pinch principle and, just due to such the currentfluctuation, the electromagnetic pulse radiation occurred.In light of the radiation frequency as a critical parameter for electromagnetic pulse radiation, in a separate chapter we analysed the radiation field and the changing ratio of EEOS current by time-frequency method, respectively. These results show that electromagnetic radiation largely stemed from the fluctuation of EEOS current. The radiation is more intensive if the fluctuation of EEOS current is rapider, and its power is larger in all the frequency component. The spectrum for the current changing ratio was identical to that of the radiation field and, thus, the theoretical and experimental results were confirmed each other.