Predicting the threshold for onset of internal electric breakdown in helical flux compression generators using CAGEN and CALE

Abstract

The objective of this work is to provide predictability for the threshold of the onset of internal electrical breakdown for helical magnetic flux compression generators (HFCG) to enable higher performance and higher voltage designs and reduce the cost of relying on empirical design methods. The Care'n LLC has used the code CAGEN [1] in conjunction with CALE [2] to investigate the phenomenon of internal electrical breakdown in these devices. The CAGEN was modified to compute the peak electric field strength between the armature and the stator as well as between adjacent wires of the stator. Shock compressed gas within the HFCG plays an essential role so the 2-D hydro-code CALE was necessary in order to get a full prediction of the thresholds. An overview of the modeling and the comparison of experiment are presented. An issue is the role bifurcations play in the electric field breakdown. A new code BSBIF [3] models some of the effects. In order to confirm the modeling, a set of very special HFCGs were fabricated and then fired by Hyperspectral Sciences, Inc. The fabrication details [4], the experimental set-up, and the measurements [5] were entirely the work of HSI.