Coordinated Diagnostics for a Hydro Experiment Driver

Hydrodynamic testing constitutes a large part of the Stockpile Stewardship program. The increasingly complex modeling of hydro phenomena requires precise information on the pulsed-power mechanisms propelling the imploding driver shell. For Atlas, a large pulsed-power machine, this means accurately recording the current waveform delivered to the target. Bechtel Nevada and Los Alamos National Laboratory diagnostic personnel have continued to improve the diagnostic suite that provides this vital information for Atlas experiments. Recent efforts to refine the accuracy and expand the dynamic range of magnetic and electric field sensors used to monitor Atlas performance are described in this paper. An optical loop for a Faraday rotation diagnostic records the total current delivered to the load with greater accuracy and less sensitivity to electromagnetic interference than the B-dot sensors. Rogowski loops provide information on relative output from individual pulsed power units. Optical switch monitors provide high- resolution simultaneity measurements. A variety of inductive loop sensors (B-dots) are used to assess current symmetry and simultaneity at varying distances from and within the central load assembly. B-dots placed in the transmission lines reveal simultaneity problems by picking up current reversal down a late-firing line, and can be used to identify the physical location of breakdowns. Load B-dots are better able to record local current transients that are blurred by the spatially averaging Faraday sensor. Techniques used to reduce spurious signals in the typically hostile pulsed-power environment are discussed and examples of results presented.