Traditionally, the 1.6-MV Marx generator offered by APELC operates at a charge voltage of 40 kV, an erected voltage of 1.6 MV, a stored energy of 260 J, and an output pulse rise time between 6-8 ns. APELC has developed a pulse conditioning system (PCS) that can be retrofitted into the existing MV Marx generator housing to improve output pulse rise time at a minimal cost of stored energy. The performance characteristics of the newly developed PCS driven by a slightly modified version of APELC's MV Marx generator will be provided. APELC has also retrofitted its staple 15-stage, 33-J, Marx generator with a scaled version of the same PCS. Preliminary results of the scaled version of the PCS are presented as well.

Compact Marx generators modified for fast risetime

APELC has developed an Impulse Radiating Antenna (IRA) that consists of a TEM-horn-fed parabolic reflector that is directly driven by a 22-J, 400-kV Marx generator. The system is based on standard Marx generator designs offered by APELC. The Marx generator output couples directly to the TEM horn via a transition from a coaxial geometry that approximates a standard coaxial-to-parallel plate transition. Primary design considerations that facilitate achievement of high instantaneous radiated power include appropriate Marx generator rise time, transition design, and TEM horn focal point positioning. Data collected over the course of the system design is presented.

A Marx generator driven impulse radiating antenna

Drilling is a part of our everyday life. The present drilling technologies are reaching their efficiency limits, therefore some novel alternatives are needed. A promising method is plasma channel drilling (PCD), where a rock is fragmented with high voltage pulses. Due to the specifics of the process, PCD operations require an isolating medium, usually water, around the electrodes (drill bit). When a very fast rising high voltage pulse is applied to the rock surface the electrical strength of the rock is lower than that of the surrounding water. Thereafter, the electrical breakdown creates an arc in the rock, which by thermal expansion causes mechanical fragmentation. So far, the main research has been done with large scale Marx generators with drill bit sizes of more than 10 cm. Additionally, only high energy pulses have been applied to the rock. Therefore, in this thesis the focus is on studying the lower limits of PCD, designing suitable compact modulators and experimentally finding optimum energy levels. In order to define specifications for the pulse generator, a literature review was conducted. For water, several scientific sources were

Compact Pulse Modulator for Plasma Channel Drilling

Applied Physical Electronics, L. C., (APELC) offers many Marx generators with stored energies ranging from 5 mJ to 1.8 kJ. The line of Marx generators offered by APELC can be used in a variety of applications including flash x-ray, high-power RF, high-power microwave, test and evaluation, triggering, and material studies. The MG15-3C-940PF (MG15), in particular, has seen wide use and integration into many systems over the past several years. The MG15 is a 33-J, 50-Ohm source and is capable of limited duty at 150 Hz at a maximum output voltage of 300 kV on to a matched load. The range of capabilities and custom configurations achieved by the MG15 as well as a sampling of the applications featuring the use of the MG15 will be presented. Recent additions to the capabilities of the MG15 include sub-ns rise time, jitter of less than 2 ns, and an energy density approaching 3.2 mJ/cm3 (90 J/ft3).

A versatile Marx generator for use in directed energy and effects testing applications

Applied Physical Electronics, L. C., (APELC) has developed a suite of high-power, wideband, dipole antennas targeted for use by the test and evaluation and the directed energy communities. Four dipoles spanning the frequency range of 50 to 500 MHz have been developed, manufactured, and used to support testing for various customers. The suite of dipoles was developed to address the new MIL-STD 464 C and all of the dipoles can be sourced by the APELC MG15-3C-940PF Marx generator. The dipoles feature corner reflectors to increase their directivity, which act to reduce side lobe levels. Additionally, a common, proprietary connector is implemented into the design of each dipole to facilitate the interchange of dipoles during deployment or testing scenarios. The dipoles manufactured to date vary in size from 20 cm in diameter and 245 cm in height to 17 cm in diameter and 37 cm in height for the 60-MHz and 400-MHz dipoles, respectively. The average amplitude of the peak electric field measured 110 kV/m and 200 kV/m for the 60-MHz and 400-MHz dipoles, respectively (electric field strengths normalized to 1 meter from source). Temporal and spectral data will be presented for each dipole offered and methods for obtaining higher peak electric field amplitudes will be discussed.

Modular, high-power, wideband transmitters for electromagnetic environmental effects (E3) testing

The compact, wave-erection, GW-class Marx generator has been previously reported for use in 5 ns to sub-ns risetime pulsed power applications. This generator topology has recently been adapted for high Pulse Repetition Frequency (PRF) applications and is the basis for a new high-PRF pulsed power system. The 33-J generator is capable of delivering a 300-kV pulse into a matched 50-Ohm load, or 600 kV into an open circuit. The high-PRF system includes an 8 kJ/sec TDK-Lambda high-voltage power supply and an APELC trigger and control unit. The APELC trigger unit contains a 150-mJ thyratron-based pulser and facilitates the synchronous pulse charging of the Marx generator. Additionally, the trigger unit provides analog output signals of the thyratron and Marx charging signals and features LED diagnostics and fault indicators on the front panel. Applications of the high-PRF system include sourcing of High Power Antennas. Design considerations, system architecture, and experimental results of the high-PRF pulsed power system are presented in this paper.

Compact 200-Hz pulse repetition GW Marx generator system

Some modern pulsed-power applications benefit from a fast-rising trigger pulse which can minimize temporal jitter or ensure a desired mode (e.g. multi-channel spark gap) of breakdown ensues. Applied Physical Electronics, L. C., (APELC) has developed a low-cost 400-ps rise time Marx generator for low-energy triggering applications. The low-cost Marx is designed into a printed circuit board (pcb) geometry and uses inexpensive, off-the-shelf components. In a typical configuration, the Marx has an erected voltage of 10 kV, a stored energy of 5 mJ, and a risetime near 400 ps. The Marx has been operated at a pulse repetition frequency of 250 Hz. Other potential uses include sourcing compact antennas, driving laser diodes, and biological plasma applications.

T. R. Smith

Papers

Compact 200-Hz pulse repetition GW Marx generator system

Low cost 400-ps rise-time circuit-board Marx generator