Field-containing inductors are required in certain simulator applications e.g., elements of pulse shaping networks, terminators for transmission lines etc. Typical coils such as solenoids have a large magnetic dipole moment resulting in excessive interfering magnetic fields. An improved design based on the traditional toroidal coil windings is presented. This new design consisting of two windings is capable of higher voltage operation. Optimal shapes, energy and forces exerted are also discussed. The normalized plots of attainable inductance for varying geometrical parameters presented in this note should prove useful in future designs and applications.

Design studies for a full threat siimulator to drive PRS implosions to around 50 MA in 250 ns showed the importance of Fast Marx Generators (FMG's) with intrinsic discharge times (LC)'" significantly less than the present state-of-the-art in large machines (e.g. 2 500 ns in the SNL "Z'). Energy, size, complexity, and therefore cost are significantly reduced, and the need for intermediate stages of power gain are eliminated as FMG discharge time approaches an optimum (around 125 ns for 250 ns implosions) [l]. We describe designs for 175 ns and 300 ns FMGs and specific components that are being developed for use in large systems.This FMG technology development builds in !part on that of systems built by the USA DoD in the 1970s and 198O's, which are also summarized. This technology can be applied to either of the fast Marxes and to the LTD 'described in Ref. 1 and to upgrades of existing systems such as the Z refurbishment. Basis of Marx RequirementsThe study in [ 11 addressed pulse power systems that drive 250 ns Z pinches intended to produce 400 kJ of krypton K-line x-rays, either a single > 50 MA module or four > 30 MA modules with separate pinches. Present-day Marxes with (LC)'" times > 500 ns, coupled to the Zpinch via water transfer capacitors were found compatible with single module design but could not be fitted together to drive four close-spaced Z-pinches. If the Marx (LC)'" time was reduced to 300 ns, water peaking circuits could be used; the one-and four-module designs were both feasible, the single module using 96 parallel Marxes, and the water volume and intermediate switching difficulties were much reduced. Marxes with (LC)In = 175 ns could drive the Z-pinch directly without needing water, the single module now needing 256 Marxes in parallel. Marx voltages were in the 6-10 MV range. Using 200 kV pulsers in LTD stages to achieve: (Le)'" = 125 ns was also considered, e.g. using 448 pidsers in parallel and 45 independent sets of these in series. *Work sponsored by rhe Defense Threat Reduction Agency.Ref. 1 compares the system designs based on transfer, peaking, Marx direct drive and LTDs. Here we consider possible designs for the Marxes with (LC)ln = 300 ns and 175 ns that Ref. 1 showed to be desirable. We show the relation between these and systems built by the US DoD in the 1970s and early 1980s. We describe how the earlier designs achieved performances at or beyond those now postulated even for LTDs. Marx DesignsThe capacitor designs for the (LC)'" = 175 ns and the (LC)In = 300 ns Marxes are illustrated in Figure 1. Both consist of rectangular plastic-cased capacitors with two parallel bar output connectors on one 60 cm wide end face. These electrodes connect to rail spark gaps that switch one capacitor to the next adjacent stage. The (LC)'" = 175 ns Marx (Figure la) uses 600 nF, 100 kV (k 50 kV) capacitors 60 cm wide, 6.5 cm thick, and 50 cm long. It has approximately 94 stages when used in a 400 kJ source or 62 stages when used in a 100 kJ source. The internal capacitor construction is illustrated ...

Abstract-We have used Stark broadening measurements of the HO emission line to determine the temporally and spatially resolved electron density in laser-triggered hydrogen sparks. In this paper the results of this work are presented and compared with earlier work on conventional overvolted sparks.

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