J. R. Mayes

Marx generators for high-power RF and microwave applications

Recent technological advancements in the field of directed energy have led to increased demand for sources capable of driving high-power RF and high-power microwave (HPM) radiators. APELCs line of Marx generators are uniquely qualified for use in various directed energy applications. Extensive testing performed on a 33-J Marx generator, which has been used as a source to drive various RF loads, will be summarized. Testing included characterizing the thermal behavior of the Marx generator during operation at various pulse repetition frequencies as well as monitoring output pulse characteristics and reproducibility. Pulse characteristics for nine other Marx generators varying from 10 mJ to 1.8 kJ in output energy will also be provided. In addition, measured RF and HPM data from various radiators sourced by APELCs Marx generators will be presented.

A compact high power wideband system

A number of recent efforts have been made to develop high power wideband sources for test and evaluation and general electronic disruption. Applied Physical Electronics, L.C. has developed technology covering 100 MHz to 400 MHz, and is continually working to broaden this area of coverage. The system is based on a single compact pulse power source, capable of delivering 1.7 GW peak power with repetition rates up to 200 Hz. Interchangeable dipole antennas are connected to the pulse power source via high voltage cabling, and are capable of radiating electric field strengths of several hundred kV/m. This paper presents the basic characteristics of the system, followed by experimental data.

Compact HV-Capcitor Charger

Summary form given only. We are reporting on a compact high power charger which is integrated into compact Marx Generators for rep. rated High Power Microwave generators and other Pulsed Power Applications. The charger uses rectified AC mains input voltages of 120V single Phase or 208V three phase and produces output voltages of up to 50 kV with HV output power levels of 10 kW. The rep. rate capability is up to 100 Hz. Major advancements over previous designs are current mode control of the main inverter, improved efficiency through advanced transformer design and improved feedback control.

Modular interchangeable high power helical antennas

Helical antennas are very appealing for their conformal and relatively small geometries. Moreover, helical antennas can be impulse excited, producing several cycles of resonant energy at a designed frequency, or resonantly-driven by a frequency matched resonator. Applied Physical Electronics, L.C. has previously reported results from impulse excited helical antennas. Those efforts have been continued to result in a family of interchangeable antennas sourced by a common compact pulse power source. This paper describes the system, including the pulse power and the helical antenna loads, supported by simulations and experimental results.

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

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).

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

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.

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

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.

Compact, DC-powered 100Hz, 600kv pulsed power source

A DC-powered, compact source capable of delivering in excess of 300 kV into a matched load is realized driving a 16-stage Marx generator with a 10 kJ/s rapid capacitor charger. The system is capable of delivering 100 J per pulse at a maximum pulse repetition frequency of 100 Hz. The Marx generator and capacitor charger are housed in a cylindrical package with approximate dimensions of 12”X60”. The pair are powered from a 300VDC bus. The unit is controlled remotely via a fiber-optically isolated micro-controller which provides the gate drive signals and user interface for the rapid capacitor charger. Performance data for the Marx generator and the capacitor charger is presented in this paper.

Compact HV-Capacitor Charger

We are reporting on a compact high power charger which is integrated into compact Marx generators for rep. rated high power microwave generators and other pulsed power applications. The charger uses rectified AC mains input voltages of 120 V single phase or 208 V three phase and produces output voltages of up to tens of kV with HV output power levels of 10 kW. The rep. rate capability is up to 100 Hz. Major advancements over previous designs are current mode control of the main inverter and improved voltage feedback control.

Computer-controlled RS-105 test system for 1-M EUTS

Test procedure RS-105, within MIL-STD-461F, prescribes the use of a transverse electromagnetic (TEM) cell, or parallel plate transmission line to test equipment and subsystem enclosures against a non-classified form of the E1 nuclear electromagnetic pulse (NEMP) waveform [2]. A system is described which is capable of exposing a 1-meter cubed piece of equipment under test (EUT) to the 50 kV/m double-exponential waveform outlined in the standard. A Marx generator and peaking circuit are used to drive a TEM structure which has been optimized for performance in the metrics of waveform fidelity, mechanical strength, and reduced cost. The computer control, data acquisition, and reporting system are also discussed.