Evaluation of pulsed power architectures for active detection

Intense pulsed active detection (IPAD, [1]; also see presentations at this conference by B.V. Weber, et al., D.P Murphy et al., S.B. Swanekamp et al. and J.C. Zier, et al.) has been proposed as a means of detecting contraband fissile material from a distance. In this approach, an intense bremsstrahlung pulse is used to induce photo fission, the products of which are detected. In this work, we report on an initial effort to evaluate the applicability of various pulsed-power architectures to this approach. The electron energy is 12 MeV with an effective electron charge at 12 MeV of 3 mC to 5 mC delivered in <; 100 ms, in either a single pulse or a burst. The eventual goals for the accelerator are compactness, especially short length; relatively light weight; transportability; and ease of setup and operation in the field. We first consider designs that could be constructed in a few years with minimum development. We compare induction voltage adders (IVA), ferrite-core linear induction accelerators (LIA), and linear transformer drivers (LTD). Conceptual point-designs are developed for each approach using essentially demonstrated technology, though the LTD assumes scaling and repackaging. The IVA design was considered for further design development [2]. We then sought approaches that are not demonstrated technology but have promise for achieving substantially less weight and volume. We considered recirculating LI As, auto-accelerators, air-core LI As, dielectric wall accelerators, and vacuum inductive stores with plasma opening switches. A partial pre-conceptual design of a 100 kA, single-pulse air-core LIA suggested that this might be a promising advanced candidate, and it is described here. An evaluation of the other advanced concepts will be published elsewhere [3].