ZR Marx Capacitor Life Test and Production Statistics

Following an extensive vendor evaluation¹ process, Sandia National Laboratories (SNL) chose General Atomics Electronic Systems to supply 2500 units of 2.6 uF 100 kV Marx Generator capacitors necessary for the refurbishment of the "Z-machine". The new capacitors replace the 1.3 uF 100 kV capacitors originally installed in this large pulse power machine, doubling the energy within the same volume, and permitting the use of existing Marx hardware. Low inductance (< 30 nH), high peak current (170 kA nominal rating), and reliable lifetimes were basic requirements that eliminated alternative technologies. The selected production capacitor, GA-ESI Part Number 32896 and a similar GA-ESI design, P/N 32897, were both life tested at 100 kV and the 32896 at 110 kV ². Manufacture of the production capacitor design began in the spring of 2003 and was completed in early 2005 with a yield greater than 98%. This paper will review the life data and compare the Weibull distribution of P/N 32896 with one derived from combining the life data from the two similar designs. The production acceptance test failure modes will be discussed and quantified.