Protrusions on the surfaces of electrodes used in high voltage spark gaps lead to local field enhancements, which lower the self-breakdown voltage of the spark gap. Stainless steel, brass, and copper-tungsten electrodes have been tested in a 5-30 kV, 4-25 kA, .1.6 Caul/shot, unipolar, pulsed spark gap with N2 gas or air. The heights and bases of variously shaped protrusions on the surfaces of t...

Electromagnetic localization and existence of gap solitons in nonlinear metamaterials, which exhibit a stop band in their linear spectral response, is theoretically investigated. For a self-focusing Kerr nonlinearity, the equation for the electric field envelope with carrier frequency in the stop band where the magnetic permeability μ(ω) is positive and the dielectric permittivity ǫ(ω) is negat...

A spark gap at pressures from 100 kPa to 7 MPa with various gases is fired by overvolting the electodes. The recovery of the gap is studied using a second identical pulse to test the voltage holdoff during the recovery period. A TV camera, interferometer and a spinning mirror camera are also used to record arc locations and density profiles. The gas is stationary during the recovery. Breakdown ...

The erosion rates for hemispherical electrodes, 2.5 em in diameter, made of graphite, copper-graphite, brass, two types of copper-tungsten, and three types of stainless steel have been examined in a spark gap filled with air or nitrogen at one atmosphere. The electrodes were subjected to 50,000 unipolar pulses (25 )ls, 4-25 kA, 5-30 kV, 0.1-0.6 Coul/shot) at repetition rates ranging from 0.5 to...

Apache Spark has become a key platform for Big Data Analytics, yet it lacks complete support for debugging analytics programs. As a result, the development of a new analytical toolkit can be a painstakingly long process [7, 2, 4]. To fill this gap, we are developing Spark-BDD (Big Data Debugger), which brings a traditional interactive debugger experience to the Spark platform. Analytic programm...

During these last years, the evolution of the machining speed of the EDM processes has become a key challenge for this technology. The recent progress made on the spark generators leads to a higher production speed in all processes such wire EDM, die-sinking, drilling, milling, etc. Nevertheless, if the electrical process is developing fast, many limiting factors still remain under investigatio...