Lanterna Rally

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Published: 1998

Total Pages: 6

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High explosive pulsed power (HEPP) is a specialized subset among pulsed power endeavors which takes advantage of the very high energy density available in both magnetic fields and high explosives (HE). To introduce basic concepts, the author divides HEPP components into generators (magnetic field (B) or current (I)) and switches. Magnetic field and current generators start with magnetic field trapped in a conducting volume. Magnetic flux can be expressed as either LI or BA, where L and A (inductance and cross sectional area) are both geometry dependent circuit properties. In a purely inductive circuit, flux is conserved, so L1I1=L2I2 or B1A1=B2A2. In the technique, HE is used to propel circuit elements that perform work against the trapped magnetic field as L or A is reduced, yielding increased I or B. Throughout this paper, the author uses the term flux compression generator (FCG) for these devices, although the reader will find a variety of acronyms in the literature. A good primer on FCG's is by Fowler et al. HE is also used to provide opening and closing switches for HEPP circuits. Closing switches do not require great sophistication, and they don't discuss them here. Opening switches typically use the energy of HE to rapidly reduce the current carrying cross section of a particular circuit element, and often require sophisticated detonation systems to match the contour of that element (e. g. cylindrical). This may either cause a direct increase in resistance or create the circumstance in which the remainder of the material fuses due to ohmic effects. Many good papers on explosive-driven opening switches can be found in previous Megagauss conference proceedings, and these are also a good source for information regarding HEPP endeavors outside the US, which is beyond the scope of this paper.