Technical Publications

Design and Performance of a 4 MV, 14KJ Marx Generator, J. R. Mayes, C. Hatfield, J. Byman, D. Kohlenberg and P. Flores, IEEE Pulsed Power Conference, Orlando, FL, 2019.

Abstract

Applied Physical Electronics, L.C. (APELC) has designed, built, and characterized a large Marx generator capable of a maximum erected voltage of 4 MV and a maximum pulse energy of 14.5 kJ. The generator is charged using a dual polarity charging topology, which helps reduce the source impedance to approximately 70 Ohms. When driving a matched resistive load, a peak power of 230 GW is delivered, with an approximate rise time of 100 ns and a pulse width of approximately 300 ns. The generator is uniquely designed to be generally insulated with transformer oil, but switched in a dry air medium. The 42 spark gap switches are uniquely grouped in sets of six, bringing in the advantages of UV coupling, and gap pre-ionization, to better switching performance.

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A versatile Marx generator for use in directed energy and effects testing applications, T. A. Holt, J. R. Mayes, M. B. Lara, C. Nunnally, J. M. Byman, and C. W. Hatfield, Pulsed Power Conference, 2011.

Abstract

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).

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LOW COST 400-PS RISE TIME CIRCUIT-BOARD MARX GENERATOR, C. NUNNALLY, Matthew B. LARA, T. R. SMITH, J. R. MAYES, CONFERENCE OF RECORD, 19TH IEEE INTERNATIONAL PULSED POWER CONFERENCE, CHICAGO, IL 2011.

Abstract 

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.

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Experimental Results of a 10-Element, Gatling-Styled Marx Generator System, J.R. Mayes and W.J. Carey, Conference Record for the 29th International Power Modulator Symposium, Atlanta, GA, 2010.

Abstract

A Gatling Marx generator system has been previously presented. This effort focused on the summation of high voltage pulses, delivered by multiple unique Marx generators, by a common adder element. More recent efforts have focused on understanding the system’s functionality and uniqueness. This paper discusses the
experimental results of a ten-element Gatling system, with discussions and demonstrations illustrating the functionality of the Gatling system. Topics include
demonstrating the ability to achieve extreme repetition rates in a burst mode, pulse coding techniques and wave shape synthesis. The Marx generators, for this effort, were supported by a common trigger source and a common charge voltage source configured for discrete voltage pickoffs. Theoretical considerations are made and supported by experimental results.

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Development of a Dual Polarity Marx Generator Designed for Pulse Charging a Dipole Antenna, J.R. Mayes, C.W. Hatfield and J.D. Dowden, Conference Record for the 29th International Power Modulator Symposium, Atlanta, GA, 2010.

Abstract

Dipole antennas have recently seen a lot of use for the generation of high-power, wideband RF. Typically, a single-ended pulse generator, such as a Marx generator or a Vector Inversion Generator (VIG) pulse charges a dipole, which has an integrated resonator. Once charged, the resonator switches and the cyclic energy is dissipated by the dipole geometry. There is a desire to increase the radiated field strengths of these devices, which requires larger pulse charge voltages.

Applied Physical Electronics, L.C. (APELC) has been developing a dual-polarity Marx generator for pulse charging the dipole with a double ended, or a balanced source, hoping to achieve greater efficiencies in the radiated electric field. The APELC generator is capable of delivering +/- 300 kV pulses onto 50-Ohm coaxial cables, with low temporal jitter. This paper discusses the design of the generator, as well as experimental results. Included, is a comparison of the dipole radiation when sourced by a single ended charge versus a double ended charge.

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Marx generators for high-power RF and microwave applications, Thomas Holt, Jon Mayes, Clay Nunnally, Matt Lara, Mark Mayes, Chris Hatfield, and Jeremy Byman. 2010 Power Modulator and High Voltage Conference.

Abstract

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. APELC’s 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 APELC’s Marx generators will be presented.

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Compact Marx Generators Modified for Fast Risetime, T.A. Holt, M.B. Lara, C. Nunnally and J.R. Mayes, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

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.

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Design and Performance of an Ultra-Compact 1.8-KJ, 600-KV Pulsed Power System, C. Nunnally, J. R. Mayes, C. W. Hatfield, J. D. Dowden, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

A new, high-energy-density Marx generator has been developed for High Power Microwave (HPM) applications. The generator (P/N: MG30-3C-100NF) has been shown to deliver 5 GW to a 25 Ohm load with a peak pulse voltage of 300 kV. A modular close-packing geometry combined with mica-film capacitor technology results in a 1.8 kJ energy storage capacity in a 20 in. diameter x 45 in. cylindrical vessel. The compact architecture accomplishes a high energy per pulse, but also facilitates a relatively low inductance of the system which is characterized by a 90 ns voltage risetime when discharged into a matched resistive load. The system includes an EMI-hardened power electronics suite which includes a solid-state trigger generator, compact HVPS, and a digital pressure regulator. The system requires only pressurized dry air for insulation, operates on an internal prime-power battery pack and is controlled via a fiberoptic remote for ease of use on remote platforms. The system design and pulse characteristics are presented in this paper.

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Compact 200-Hz Pulse Repetition GW Marx Generator System,W. C. Nunnally., J. R. Mayes, T. A. Holt, C. W. Hatfield, M. B. Lara, T. R. Smith, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

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 it 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.

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Development of a Sequentially Switched Marx Generator for HPM Loads, J.R. Mayes and C.W. Hatfield, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

Relativistic Magentrons prefer trapezoidal-shaped, high voltage pulses, as opposed to the double exponential waveshape characteristic of a Marx generator. Traditional approaches use intermediate Pulse Forming Lines (PFNs) or stacked Blumleins to create the desired pulse shape. Marx generator-driven PFNs are unacceptable, due to their size and additional overhead. Stacked Blumleins are very difficult to switch, when a large number of lines are required, which results in small line impedances. Applied Physical Electronics L.C. is developing a novel Marx generator topology that results in a rectangular waveshape, without additional pulse conditioning hardware. The topology is based on a multi-generator design. Each generator is sequentially switched to the common load, so as to simulate a rectangular waveshape. In essence, the desired rectangular pulse shape is built temporally, and the capacitance of the load can be designed to reduce the ripple in the load waveform. Each generator can be uniquely charged and triggered, resulting in a programmable, high voltage waveform generator. The generator is described for its geometry. Simulation and experimental results are provided.

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Compact, DC-Powered 100Hz, 600kV Pulsed Power Source, M.B. Lara, J.R. Mayes, W.C. Nunnally, T.A. Holt, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

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 fiberoptically 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.

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A Marx Generator Driven Impulse Radiating Antenna, T.A. Holt, M.G. Mayes, M.B. Lara, J.R. Mayes, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

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.

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Dual Polarity MV Marx Generator System, J. R. Mayes, E. Eubank, M. Lara and M. G. Mayes, Conference Record for the 27th International Power Modulator Symposium, Washington, DC, 2006.

Abstract

Two compact MV Marx generators are arranged to fire into a common spark gap and designed to deliver pulsed voltages in excess of 3 MV. Each generator is
characterized by 40 stages of 8.1 nF capacitance and a charge voltage from 20 – 40 kV, which results in an erected voltage of up to 1.6 MV and pulse energies of
more than 250 J. Each generator has an integrated controllable power supply and pressure control, and is battery powered. The two generators are charged with
opposite polarity voltages, which can result in a differential pulsed magnitude of 3.2 MV. A central thyratron trigger source is remotely located and is designed for delivering two simultaneous high voltage trigger pulses to each generator. Design considerations are presented, as well as experimental results.

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A Moderate Energy, High Repetition Rate Marx Generator System for Pulse Charging Wide Band Antenna Structures, J. R. Mayes, E. Eubank, M Lara and M. G. Mayes, Conference Record for the 27th International Power Modulator Symposium, Washington, DC, 2006.

Abstract

An ultra compact Marx generator system is fabricated for driving a wideband antenna structure with high repetition rates. The generator is designed to deliver 100 J per pulse, with an erected voltage of 640 kV. The generator employs an inductive element charging topology, which allows the 16 stages to be rapidly charged to a maximum voltage of 40 kV. The generator also integrates a 10 kW rapid capacitor charging power supply, which compactly mates to the end of the Marx generator. Design considerations are presented, as well as experimental results.

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Compact Flash X-Ray For Radiographic Applications, J.R. Mayes, SPIE Defense and Security Conference, Orlando, FL 2006.

Abstract

Compact Marx generators based on the wave-erection principle are ideal drivers for flash x-ray systems. Traditional Marx generator design techniques lead to slow rising voltage pulses, marked by high impedances, large temporal jitter values and inefficient transfer of energy. As a result, larger pulse generators are fabricated to overcome these shortcomings, which results in excessive volumes and weights. Applied Physical Electronics, L.C. has been developing Marx generators for many years based on the wave-erection principle. As a result, generators with relatively low source impedances, high impulse voltages and compact geometries are making their way into use as portable flash xray drivers. More recently, APELC is extending their compact designs into complete flash x-ray systems, including the diode load. This paper discusses two generator systems that have been developed, basic diode geometries that will be incorporated, and a new novel system designed to generate up to an x-ray energy of 3.2 MeV.

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An Enhanced MV Marx Generator for RF and Flash X-ray Systems, J.R. Mayes, M.B. Lara, M.G. Mayes and C.W. Hatfield, 15th IEEE International Pulsed Power Conference, Monterey, CA 2005.

Abstract

A compact MV Marx generator has been previously presented for its basic performance[1]. This generator is based on a 40-stage design and has been demonstrated to deliver more than 850 kV onto a 50 Ω cable. Work has continued on this generator to improve its performance, namely with charging efficiency and control, and new efforts are aimed at developing integrated and modular loads. This paper discusses improvements made with the system, as well as its ability to drive a wide variety of loads including a flash x-ray load. Experimental results and discussion conclude this paper.

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A Novel Marx Generator Topology Design for Low Source Impedance, J.R, Mayes, M.G. Mayes, and M.B. Lara, 15th IEEE International Pulsed Power Conference, Monterey, CA 2005.

Abstract

The typical Marx generator designs employ a single stage switch, which usually results in a high source inductance, and ultimately high source impedance, relegating the Marx generator to the role of a high voltage pulse charging source. A low impedance Marx generator may be used to directly source low impedance loads, such as High Power Microwave loads. Applied Physical Electronics, L.C. (APELC) has developed a new Marx topology based on distributed stage capacitance and parallel stage switches that has been demonstrated to reduce the generator’s series inductance. The erected Marx voltage is 1 MV, with a source impedance of 18 Ω. This paper discusses the Marx topology, with demonstrations made to illustrate the topology’s effectiveness for the APELC MG20-24C-2000PF

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A Modular Compact Marx Generator Design for the Gatling Marx Generator System, J.R. Mayes, M.B. Lara, M.G. Mayes and C.W. Hatfield, The 15th IEEE International Pulsed Power Conference, Monterey, CA 2005.

Abstract

The Gatling Marx generator system has been previously discussed for its ability to deliver energy from multiple generators into a single cable with demonstrations of the Gatling Marx in [1]. New efforts with the system bring the need for a modular and compact design, high repetition rate capability, and enhanced controller capabilities, including control over the charge voltage, pressure regulator, and trigger. Control over each component via an embedded microcontroller is necessary to meet the system’s promised performance. Design considerations are presented, as well as preliminary results with the ancillary components and loads.

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A Compact MV Marx Generator, J.R. Mayes, M.G. Mayes and M.B. Lara, Conference Record of the 26th International Power Modulator Conference, San Francisco, CA 2004.

Abstract

A compact MV Marx generator is presented. The generator employs a modular geometry designed for decreased volume, enhanced performance ease of maintenance. The generator is very well suited for the direct generation of Narrow Band and Ultra Wide Band energy, as a high voltage trigger generator or as a flash X-ray source. The characteristics of the generator are discussed.

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Compact Pulsed Power Sources, J.R. Mayes and W.J. Carey, SAE Aerospace Power Systems Conference, 2002.

Abstract

Marx generators have been traditionally relegated as pulse-charging supplies for a variety of applications including the generation of High Power Microwaves, or RF energy. Compact models have served as suitable trigger generators for larger systems. However, recent work has demonstrated the compact Marx generators for directly generating RF energy.

This paper discusses two compact Marx generators developed for RF applications. General performance characteristics for each generator are discussed, as well as efforts to minimize the temporal jitter of these systems so as to make them viable sources for radar transmitters. The Gatling Marx generator is presented as a multiple generator RF source for weapons and radar transmitters. Finally, the generation of RF and microwave energy is discussed.

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The Gatling Marx Generator System, J.R. Mayes, W.J. Carey, W.C. Nunnally and L. Altgilbers, The 13th IEEE International Pulsed Power Conference, 2001.

Abstract

Traditional multi-pulse systems require multiple uncoupled sources, each driving a unique load. A phased array system, for example, may use multiple sources, each
with its own antenna element, to radiate multiple pulses or a steered single pulse to a target. However, the Injection Wave Generator (IWG) has brought the concept of
coupling multiple sources with a single load transmission line. Thus, multiple sources may be used to drive a single load element.

In the case of a radar source, the overall volume of the system may be drastically reduced with only one antenna. This paper discusses a Marx generator-based IWG system designed to deliver multiple high voltage pulses to a single load. The pulse magnitudes are on the order of several hundred kV, and with a pulse separation of 10’s of nanoseconds. The system is described with an emphasis on the results of the experimental system. Radiation results, with the Gatling system driving a single TEM horn antenna are presented and discussed.

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Sub-Nanosecond Jitter Operation of Marx Generators, J.R. Mayes, W.J. Carey, W.C. Nunnally, and L. Altgilbers, The 13th IEEE International Pulsed Power Conference, 2001.

Abstract

Low energy, high peak power Marx generators are finding applications in Ultra Wideband radar and high power microwave systems. In many cases, these systems require very precise control over the delivery of the pulse from the generator. For example, unique systems might be used for bi-static radar, and excessive temporal jitter between the generators may add ambiguity to the measurement. A 17 stage Marx generator was fabricated to study techniques for reducing the jitter in a multi-spark gap system. This paper presents the results of a jitter study.

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Compact Marx Generators for the Generation of High Power Microwaves, J.R. Mayes, W.J. Carey, W.C. Nunnally, L. Altgilbers and M. Kristiansen, High Power Microwave Conference, 2001.

Abstract

Traditional Marx generators have been primarily reserved for energy storage and pulse-charging sources. However, recent work has demonstrated the Marx generator’s effectiveness in delivering ultra-short impulses at very intense power levels. This paper discusses two very compact Marx generators capable of delivering voltage pulses of several hundred kV, durations of several nano-seconds to 10’s of nanoseconds, and risetimes as fast as 200 ps. Performance of these generators will be discussed as well as radiation results with the generator directly driving a TEM horn antenna. Further discussion will be made toward the application of the Marx generator driving various microwave devices including the Backward Wave Oscillator.

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A compact 700-kV erected pulse forming network for HPM applications, C. Nunnally, Pulsed Power Conference, 2011.

Abstract

Increased interest in deployable High Power Microwave systems has led to demand for compact pulsed power drivers for HPM loads, such as magnetrons, that are sensitive to pulse shape. APELC has developed a 600-J, erected pulsed-forming network capable of delivering a 200-ns square pulse to HPM loads. The generator consists of eight, erected pulse-forming sections charged from a common supply. The resonant sections combine to produce a Fourier-approximated square pulse at the load. Pulse characteristics include a FWHM of 200-ns, risetime of 25 ns, and a decay time of 60 ns. The generator is housed in an 18” diameter by 60” long pressure vessel and uses only compressed dry air for insulation. The generator is capable of 50-Hz pulse repetition frequency and features soft-failure modes for continued operation in the event of component failure.

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EMP Footlocker: A Portable High-Power Electromagnetic Source For Mobile Platforms, Clay Nunnally, J. Byman, M. Lara, W.C. Nunnally, D. Kohlenberg, and C. Hatfield, IEEE Pulsed Power Conference, 2015.

Abstract

International interest in electronic-warfare tools which can deliver scalable, non-lethal effects on potential targets, such as drones, has led to the development of portable high-power electromagnetic sources. Subsequent testing has indicated that
such sources can be useful for studying effects on critical infrastructure, asymmetric threat hardware, and electronic systems. One particular application and has led Applied Physical Electronics LC to develop a mobile, high-power, electromagnetic pulse generator which uses a wideband antenna and an integral reflector to meet the unique needs of its intended task. This paper discusses APELC’s development of the “EMP Footlocker”, its mechanical characteristics, control scheme, and electromagnetic signature.

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Modular Interchangeable High Power Helical Antennas, M.B. Lara, M.G. Mayes, W.C. Nunnally, T.A. Holt and J.R. Mayes, Pulsed Power Conference 2011.

Abstract

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.

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Modular, high-power, wideband transmitters for electromagnetic environmental effects (E3) testing, T.A. Holt, M.B. Lara, C. Nunnally, C.W. Hatfield, J.R. Mayes, Pulsed Power Conference, 2011.

Abstract

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.

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A Compact High Power Wideband System, J.R. Mayes, C.W. Hatfield, M.G. Mayes, W.C. Nunnally, M.B. Lara, T.A. Holt, and W.C. Nunnally, Conference Record for the 29th International Power Modulator Symposium, Atlanta, GA, 2010.

Abstract

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.

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Helical Antennas for High Powered RF, J.R. Mayes, M.G. Mayes, W.C. Nunnally and C.W. Hatfield, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

Radiating high power RF below 1 GHz can be difficult. Large structures are preferred for high voltage operation; however, large structures are difficult to deploy. Conversely, small geometries are more easily deployed, but insulating the high voltage can be difficult. Dipole structures have made their way into use due to the relatively simple and compact implementation; however, their radiation pattern is not desirable, since they radiate in a donut pattern, which can disrupt, or even destroy one’s own electronic controls. Impulse Radiating Antennas have been configured for wideband operation; however, their large geometry is very difficult to deploy. Helical antennas offer many advantages over other methods. The helical antenna is relatively compact, with its cylindrical geometry. The antenna’s geometry is wavelength dependent, but is acceptable from several hundred MHz and higher, with the upper limit being dominated by the high voltage operation. It offers a good gain factor and can be operated as a narrow band, or wide band device. Applied Physical Electronics, L.C. has been developing high voltage helical antennas for narrow band and wide band applications. This paper describes the fundamental operation of a 400 MHz helical antenna driven by Marx generators. Simulation and experimental results are provided.

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High Power Ultra Wideband Source, J.R. Mayes and M.G. Mayes, IEEE International Conference on Ultra-Wideband, September 24 – 26, 2007, Singapore.

Abstract

Ultra Wide Band (UWB) sources provide valuable diagnostic tools for Electro Magnetic Compatibility (EMC) and Electro Magnetic Interference (EMI) design and analysis. By radiating electronic devices or systems with UWB energy, localized resonances can be determined for a better understanding of RF coupling mechanisms, and ultimately, the vulnerabilities of the device or system. Applied Physical Electronics reports the development of an UWB system for EMI/EMC testing in both laboratory and nonlaboratory environments. The system is designed to deliver field strengths exceeding 600 kV/m at 1 m, with a spectrum of 125 MHz to 1.5 GHz. The antenna portion of the system has been tested with a low-power Marx generator source to demonstrate electric field strength of approximately 60 kV/m at 3 m. Development efforts continue to advance the system to the targeted field strength of 600 kV/m at 1 m, while compacting the system footprint for portability.

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High Voltage Properties of Insulating Materials Measured in the Ultra Wide Band, M.G. Mayes, J.R. Mayes, M.B. Lara, and L.L. Altgilbers, 15th IEEE International Pulsed Power Conference, Monterey, CA 2005.

Abstract

Numerous dielectrics have been developed for various high-voltage high-power microwave applications. The primary goals for HPM insulation are to provide adequate insulation over the lifetime of the device, provide high dielectric strength at low volume and weight, and function with minimal maintenance and ancillary components. Current testing methods for dielectric materials are antiquated processes developed around the 60 Hz machine world and prove inadequate for high-voltage high-frequencies pulses. We report the development of an insulation processing and testing system for engineering and verifying solid and resin/epoxy dielectric insulators for high-voltage radar systems in the pulse regime. The system tests material properties at high voltages over a frequency range of 100 MHz to 10 GHz. A second procedure characterizes breakdown and partial discharge thresholds. The system targets in-situ inspection of the dielectric liner within an HPM generator housing to verify insulator integrity prior to deployment.

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The Direct Generation of High Power Microwaves with Compact Marx Generators, Jon R. Mayes and William J. Carey, 14th International Conference on High-Power Particle Beams, 2002.

Abstract

High Power Microwave energy may be directly generated with ultra-fast voltage pulses driving an antenna. Recent efforts with the wave erection Marx generator have seen the production of voltage pulses in excess of several hundred kV, with rise times as fast as 200 ps. This generator has been used to source Ultra Wideband antennas as well as Narrow Band antennas, each resulting in high electric field strengths. This paper describes the Marx generator and explores its use for generating UWB and NB energy. Experimental results are presented.

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The Generation of High Electric Field Strength RF Energy Using Marx Generators, J.R. Mayes and W.J. Carey, Conference Record for the 25th International Power Modulator Symposium, 2002.

Abstract

The Wave Erection Marx Generator is proving to be an excellent high voltage source for the direct generation of RF energy. Unfortunately, effectively radiating the impulse energy is challenging, both in efficiency and high voltage-holdoff capability. Successful efforts have been made to generate RF energy in both the Narrow Band and Ultra Wideband realm, with field strengths in excess of 1 kV/m at 100 m achieved. This paper briefly describes the impulse generator and explores its use for generating Narrow Band RF energy as well as Ultra Wideband energy. Experimental results will be presented.

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The Marx Generator as an Ultra Wideband Source, J.R. Mayes, W.J. Carey, W.C. Nunnally, and L. Altgilbers, The 13th IEEE International Pulsed Power Conference, 2001.

Abstract

Traditional uses of the Marx generator have been limited to energy storage and delivery systems, such as charging capacitors or pulse forming lines. However, low energy, high peak power Marx generators are finding applications in Ultra Wideband radar and high power microwave systems. This paper discusses the compact generator as well as an assortment of impulse antennas. Experimental results, including those of the Marx generator and antenna range measurements are presented and discussed.

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Design and Performance of a 6 GHZ Analog Optical Link, M. Lara, J. R. Mayes, IEEE Pulsed Power Conference, Orlando, FL, 2019.

Abstract

Applied Physical Electronics, L.C. (APELC) has designed and constructed an analog optical link with a bandwidth of 250 kHz to 6 GHz. The system is controlled from a LabVIEW-based remote platform that provides the user with control and monitoring of the system standby function, battery charge, temperature, and attenuation. The internal step attenuator provides 60 dB of dynamic range in 1 dB increments. Internal temperature compensation allows the system to operate without recalibrations in environments where the temperature fluctuates over a wide range in one day. The link is housed in a rugged and shielded enclosure for use in external environments with extremely high field strengths. This paper describes design considerations and performance of the system.

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Design and Performance of a 2M EUT MIL STD 461(RS-105) Test System , J. R. Mayes, M. Lara, C. Hatfield, W. C. Nunnally, J. Byman, E. Perry, D. Kohlenberg, P. Flores, T. Henke and S. Del Rosario, IEEE Pulsed Power Conference, Orlando, FL, 2019.

Abstract

Applied Physical Electronics, L.C. (APELC) has built a moderate scaled test system to meet MIL-STD 461, under the RS-105 test configuration. The system is designed to test objects of up to 2 m x 2 m x 2m, with peak electric fields of up to 60 kV/m. This system uniquely uses a coaxial Marx generator, coupled with a planar peaking circuit to produce the MIL-STD waveform, which is characterized by a 1.8 – 2.8 ns rise time, and a pulse width of approximately 23 ns. This paper will describe the pulsed power source, as well as the nuances of driving a guided wave structure.

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Computer-Controlled RS-105 Test Systems for 1-M EUTS, M.B. Lara, J.R. Mayes, C. Nunnally, W.C. Nunnally, J.M. Byman, D. Kohlenberg, IEEE Pulsed Power Conference, 2015.

Abstract

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.

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A Portable MIL-STD-188-125 E1 Test System, M. B. Lara, J. R. Mayes, C. Nunnally, D. Kohlenberg, C. Hatfield, IEEE Pulsed Power Conference 2015.

Abstract

MIL-STD-188-125 establishes requirements and design objectives for high-altitude electromagnetic pulse (HEMP) hardening of both fixed and transportable systems [2,3]. A pulsed current injection (PCI) system is presented which produces a >1 kA peak current waveform suitable for compliance testing many of the systems outlined within the MIL-STD. A novel, planar Marx generator topology is utilized as the 60-Ohm Norton-equivalent source in a suitcase-style package capable of being carried by one person. Pulse characteristics, and coupling methods for wire-to-ground, shield-to-ground, and bulk cable common-mode testing are also discussed.

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An Ultra Portable Marx Generator-Based Solution for MIL-STD 461 E/F RS-105 Testing, J.R. Mayes, M.B. Lara, W.C. Nunnally, M.G. Mayes, and J. Dowden, The 16th IEEE International Pulsed Power Conference, Washington, DC, 2009.

Abstract

A parallel-plate test cell is designed and implemented for EMP testing covered under MIL STD 461E/F, testing standard RS-105. The device is constructed to give a maximum crated footprint of approximately 4ft.x 8 ft., while being two-man portable, and set-up in less than one hour. The system is driven by a Marx generator and pulseforming circuit which are designed for minimal maintenance, and maximum shot life. An integrated power electronics module contains an electronic pressure regulator, trigger module, dual-polarity high-voltage supplies, and battery, making the operation of the system safe and user-friendly by providing complete high-voltage isolation of the user via a fiber-optic hand-held remote control. Design and operational data from the tester are presented in this paper.

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Analytical Modeling of a Linear GaAS Photoconductive Switch for Short Pulse Excitation, J.R. Mayes and W.C. Nunnally, IEEE Pulsed Power Conference, 1999.

Abstract

The carrier density for a photoconductive switch is described by a single linear rate equation that is dependent on the time-varying incidental optical source. Typical solutions to this equation assume the optical source as a square pulse with instantaneous rising and falling edges; thus simplifying the solution to the problem. This paper presents an analytical solution to the rate equation with a short, gaussian optical profile. This solution leads to a PSpice model for the photoconductive switch using a time-varying resistor model. The time­ dependent conduction profile is numerically generated by the analytical solution and placed in a table definition for the time-varying resistor model. This paper discusses the analytical aspects of the solution and presents the PSpice model results, Analytical and experimental results are compared.

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Spark Gap Triggering with Photoconductive Switches, J.R. Mayes, W.J. Carey and W.C. Nunnally, The 11th IEEE International Pulsed Power Conference, 1999.

Abstract

Photoconductive switches are well suited for triggering spark gaps since the triggering event is short and requires very little energy. Photoswitches offer fast-rising pulses of short duration with voltage levels of several 10’s of kV and 10’s of ps jitter and can be very simple in design, whereas typical trigger sources require multiple stages to generate 10’s of kV needed to effectively trigger a spark gap of the same potential and usually suffer from slow risetimes. This paper presents methods aimed at triggering spark gaps with photoswitches. Both linear and non-linear photoswitches are discussed and their associated problems are presented.

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Photoswitch Material Recombination Effects on the Injection Wave Generator, J.R. Mayes and W.C. Nunnally, Conference Record for the 23rd International Power Modulator Symposium, 1998.

Abstract

The photoswitched Injection Wave Generator (IWG) is an alternate method of
generating multiple cycles of microwave energy using parallel switches in a transmission line geometry that overcomes the limitations of the traditional and present day microwave sources. The photoswitches isolate initially charged
transmission line segments from the output transmission line; with the simultaneous closure of the switches, the energy from the charged transmission line segments is released onto the output line in the form of pulses at spatial halfwavelength locations.

The generator is limited by the switches used to generate the injected pulses. As
neighboring pulses begin to overlap, the efficiency of the generator decreases and energy is shifted to the lower harmonics. This work studies the effect of switch material recombination time on the performance of the IWG. Four levels of Chromium-doped GaAs have been used for the switches, providing four unique recombination times. The generator has been tested at three operational frequencies for each material switch set.

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High-Current Arc Discharge (HCAD) Test System for Aeronautic Power, Clay Nunnally, Patrick Williams, Matt Lara, Eric Perry, Jeremy Byman, Paul Flores, Power Modulator Conference, 2016.

Abstract

High-potential DC power distribution systems such as those found in aeronautics are at risk to failures different from AC and low-voltage DC systems. Detection and mitigation of such failures are important in aerospace and other technology fields. In collaboration with the Air Force Research Laboratory, APELC has developed a high-current arc-discharge (HCAD) system for test and research applications.

The HCAD system is an instantly reconfigurable arc-discharge source capable of driving 60-Amps continuously or >1-kA in pulsed-discharge mode. The system can be configured for unipolar or bipolar power up to 600 VDC in both pulsed and continuous modes. The system employs 28 F of capacitance for pulsed discharge and uses high-current IGBTs to energize and de-energize the load. HCADS features internal current limiting resistors, a hand-held fiber optic remote, calibration fixture, and voltage and current diagnostics. This paper presents the design of the HCAD system.

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Experimental Multiple Frequency Injection-Wave Generator, J.R. Mayes, W.J. Carey and W.C. Nunnally, Conference Record for the 22nd International Power Modulator Symposium, 1996.

Abstract

The design of an optically activated multiple frequency injection-wave generator is presented. This generator naturally lends itself as a suitable microwave source for large phased arrays. The system consists of an output transmission line and static energy storage segments spatially placed with half wavelength separation. Each segment is isolated from the output line by a bulk GaAs switch. The injection-wave generator is initiated when the switches simultaneously are closed. The static electrical energy is then injected into the output transmission line, as defined by the spatial arrangement. The system is driven by a single 35 ps laser source whose output is divided by a fiber bundle for delivery to the individual switches. The versatility of the generator is demonstrated by the production of multiple frequencies. Experimental results are compared with simulation models.

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STATEMENT OF CURRENT CAPABILITIES IN FLASH X-RAY TECHNOLOGY

Abstract

Applied Physical Electronics L.C. was founded in 1998 as a pulsed power company specializing in the design, construction, and application of compact Marx generators based upon the wave-erection principle pioneered by David Platts of LANL [1]. Because of their compact form-factor, fast rise-time, low-jitter and relatively low source impedance, this style of Marx generator has become very popular as a source for flash x-ray diodes. Over the past 25 years, APELC has matured the design of these Marx generators into robust, low-maintenance, commercially available sources. Paired with APELC accessories, such as power and control racks, diagnostics, and calibration loads, these Marx generators are available as user-friendly, turn-key systems.

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