[en] An efficient PFN/Marx generator was constructed for generating high average power electron beams. The generator consists of ten 100 kV PFN stages connected in a Marx configuration. The Marx generator employs purged gas switches. This paper discusses the Marx charging power conditioning and the operation of the generator into resistive and electron beam loads

[en] The erosion characteristics of a spark gap with parallel-plane electrodes are determined at atmospheric and vacuum pressures. Erosion as a loss of electrode material is measured in a range from 200 to 1000 amperes. The severity of electrode erosion is found to be related to spot formation, switching rates, melting point of the electrode, pressure, and gap length. Erosion values for a pulsed current are given for aluminum, brass, and carbon

[en] A multistage, 4 MV, low jitter, command triggered gas switch is being developed for use on large pulse power devices. Experiments to date have shown that the performance and operational life of the switch are severely limited by mechanical and electrical failure of the insulating housing. Estimates of the internal overpressure produced during switch closure have been made which indicate the severity of the blast containment problem; this information has led to the development of a mechanically stronger switch design. Surface analyses performed on both switch electrode and insulator surfaces were used to investigate observed electrical failure of the insulators. A layer of closely spaced metal particles were found imbedded in the insulator walls

[en] Line-type pulsers operating at rep-rates greater than a few kilohertz require special circuits to insure proper operation of the switch. Specifically, thyratrons and other closing switches require a grace period of several microseconds or more before anode voltage is reapplied; this delay allows recovery and prevents reclosure of the thyratron. One method of achieving the required delay time is by using a slightly mismatched PFN and slower-than-resonant charging. However, repetition rates of line-type modulators are limited by the characteristics of resonant charging. In order to increase rep-rates, these characteristics may be modified by using a saturable reactor as a charging inductor. This paper describes design considerations and laboratory performance of saturable inductors used to resonately charge an energy storage network up to 25 kV with a delay as much as 16.5 microseconds

[en] The behavior of surface discharge switches at high pressures operating into laser and resistive loads has been studied. The experiments utilized the spark gap as a transfer switch between a pulse-charged ethylene glycol transmission line, (30 ns, 1.4 Ω) and a 17-Ω low-inductance load resistor, as well as a multiatmosphere rare-gas halide laser. The behavior of the spark gap breakdown voltage and number of channels upon charging voltage and gas pressure in the spark gap was studied in detail. The spark gap operation under laser and resistive load conditions will be compared and related to a first-order model of the gap breakdown. Scalability to higher voltages will be discussed in the context of this model

[en] Recent advances in direct lightning strike testing have been in lightning attachment test techniques and generator development using a very large Tesla Coil (51 feet wide). Breakthroughs in simulated lightning attachment to small scale replica aircraft models which can be adapted to full size operational aircraft have been made in the past year. New high voltage long arc generator developments have succeeded in producing voltages in excess of 15 million volts and arc lengths in excess of 40 feet. The shortest path from the discharge arc electrode to the model extremity using the long arc does not govern the attachment points to the test specimen as it does when a short arc is used to conduct simulated lightning testing. The system just described may also have application as an ultra-high mega-volt source for particle beam weaponry

[en] Electro-optical measurements of the electric fields along insulator surfaces have been made to determine the mechanisms associated with fast insulator flashover. Data will be presented that show the temporal and spatial performance of the surface fields prior to and at flashover for insulator surfaces oriented at 0⁰ and 45⁰ with respect to the applied field. Results show that the surface field near the cathode is enhanced and the field near the anode is reduced during the excitation. The results further show a temporal reduction in the field non-uniformity as flashover is approached. The field collapse associated with flashover occurs very rapidly for 0⁰ surfaces. The field collapse for 45⁰ surfaces begins at the anode and propagates at 0.83 cm/ns towards the cathode. Mechanisms consistent with these experimental measurements will be postulated

[en] The results of experiments designed to measure electron densities from measurements of Stark broadened spectral profiles in laser-triggered discharges in hydrogen are reported. Temporally and spatially resolved data have been obtained both during and after the arc for discharges in hydrogen. Evidence of a shockwave is presented, consistent with the observations of other investigators

[en] The TEXT Tokamak required the development of a special contact for pulsed high currents for the split coils of the poloidal system at a location which is highly inaccessible. A solution was found in the form of a special plug contact. A prototype was tested to the failure point using the discharge of a homopolar machine. Design, test setup and test results are described and the results are evaluated in view of other uses such as larger contacts and switches

[en] Inductance and resistance characteristics of single-site untriggered water switch arc-channels have been investigated by measurement of their effects on frequency and voltage gain in a water capacitor transfer circuit. Data are presented for two distinct switch configurations covering a voltage range from 3 to 6 MV, gaps from 7 to 35 cm, and mean switching fields from 150 to 350 kV/cm. A simple lumped circuit model is postulated with switch L and R varying linearly with gap spacing under low voltage conditions. Extrapolation of this zero-order model to higher voltage conditions compares favorably with measured circuit characteristics. Energy loss in the water switch is observed to be approximately a factor of two in excess of maximum losses predicted from previous estimates