Water-line design and performance of Z [pulsed power supply]

A new set of bi-plate transmission lines have been designed and installed in the water-section of PBFA-lI for the Z-pinch experiments. Thirty-six aluminum flat-plate transmission lines submerged in a water dielectric deliver a timed electrical pulse from coaxial tube sections to a ring stack section. Each of the lines are electrically isolated from each other by transit-time effects. The water-lines are configured radially at four vertical levels. Each level has nine sets of bi-plates, with a transition section that is unique to that level. Mechanically, the bi-plate sections are designed to carry both static and dynamic loads. Electrically, the lines are designed to transport electrical pulses that average 200 nanoseconds with peak voltage of 2.5 to 3.0 MV. The peak fields exceed 200 kV/cm. All line sections are a series of chromate coated aluminum plates, broken down into short, light weight sections. The design of the plates was meticulously developed using the Electro code for voltage breakdown, and NISA for mechanical analysis. Electrical losses associated with impedance mismatching and voltage breakdown were carefully reviewed. Changes in the bi-plate gap, surface shapes and electrical path discontinuities (mechanical joints) were precisely calculated to achieve maximum electrical performance and reliability. Several iterations of surface shapes and line gaps were reviewed to achieve the most desirable characteristics possible. Additional criteria required that minimal time and effort be required to remove and install the water-lines. Special hardware was developed to help meet this requirement.