Theory of intense electromagnetic pulse propagation through the atmosphere

Yee, Jick H.; Alvarez, Rodrigo; Mayhall, D.J.; Byrne, D. P.; DeGroot, J. S.

doi:10.1063/1.865872

Cited by 84 publications

(30 citation statements)

References 11 publications

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“…Numerous microwave breakdown studies have utilized alpha radiation as a pre-ionization source for CW and pulsed investigations with volume breakdown [8,9,10]. It might be possible, at least conceptually, to detect the time an α-particle produces an ionization trace in the critical volume and trigger the microwave discharge accordingly, at least at low pressures with a high enough lifetime of free electrons.…”

Section: Cw Uv Illuminationmentioning

confidence: 99%

High power microwave surface flashover seed electron production methods

Thomas

Foster

Krompholz

et al. 2010

2010 IEEE International Power Modulator and High Voltage Conference

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Surface flashover imposes a fundamental limitation to the magnitude of high power microwaves which can be radiated from the vacuum environment of the source into atmospheric conditions. Providing seed electrons through various methods allows for initiatory conditions to be more closely controlled and the delay time variations to be reduced so that developmental mechanisms can be more closely examined. The experiment uses a coaxial magnetron capable of producing a ~4.5 MW, 3 µs pulse, at 2.85 GHz propagating in the TE 10 mode. The pulse rise time measured at the window is reduced using a spark gap pulse steepening technique. The fast rise time pulse propagates through the dielectric into an atmospheric test chamber where various conditions such as gas pressure, type of gas, UV illumination, and charged particle creation by radioactive sources can be controlled. Previous research has shown the significant impacts of UV radiation on the delay time averages and statistical distributions. Surface distributed seeding sources and volume distributed sources will be discussed while the primary focus of this paper will address use of alpha radiation as an ionizing agent. Thus far, a reduction in average delay time by as much as 60% has been achieved at sub-microsecond time scales, which also significantly affected the width of the statistical distributions of the delay time. Alpha particles have a short penetration distance in air which makes them a good candidate for study since the number of electron-ion pars created along the path is large. Analysis of the alpha particles influences will be discussed along with a statistical analysis of breakdown delay in the presence of ionization.

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Section: Cw Uv Illuminationmentioning

confidence: 99%

High power microwave surface flashover seed electron production methods

Thomas

Foster

Krompholz

et al. 2010

2010 IEEE International Power Modulator and High Voltage Conference

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“…The recombination rates are too small to matter over the time dii- (6) ration of the 160-ns pulse; therefore one finds for this example that: dn -di-nqjvn = 1"ie (8) Because the collision frequency is much less than the carrier frequency, the mean energy of the free electrons is close to the quiver energy of 62 eV, and the electron velocity is given by Vim/si 6X105(C[eV))"2 4.7x 106.…”

Section: Quiver Energymentioning

confidence: 99%

<title>Designing a high-power array for a target in the upper atmosphere</title>

Myers

1993

SPIE Proceedings

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High-power microwave pulses can destroy electronics of targets at altitudes of 100 km or higher, and preliminary designs of microwave antennas driven by Relativistic Klystron Ampiffiers have been sketched.1 This paper discusses the susceptibility of the atmosphere to microwave breakdown, and the constraint on the design of a microwave weapon imposed by the need to avoid breakdown. The discussion consists of two parts.Part I outlines some relevant mechanisms of breakdown and ofthe knowledge base on which their description rests. For the interesting case of the first pulse of a train of L-band pulses, with a pulse duration of 160 ns, the condition to avoid breakdown is summarized by a bound on the energy flux of the pulse as it propagates upward across a layer at an altitude near 50 km. Subsequent pulses are subject to a more stringent bound, not yet determined.Part II presents a general model for a converging coherent microwave beam that concentrates energy flux on a target at or above 100 km while maintaining flux at 50 km below a bound expressed as a parameter. For the value of the 50-km flux bound worked out in Part I for a first L-band pulse, it is shown that, for a Gaussian current distribution with a cutoff to be described, to deliver 1 mJ/cm2 to a target at 100 km, the minimum array diameter is 730 m. This array is dense, not sparse. The minimum array diameter is achieved for a converging beam focused narrowly on the target, so that the radius of the spot of intense radiation is 20 m for this case. If a larger spot is required, then in order to avoid breakdown, the antenna array must also be larger. Other cases are calculated.Precise criteria by which to optimize current distributions for the array are not yet determined. The Gaussian current distribution is not optimal by any standard, and a better distribution would permit a smaller diameter array without atmospheric breakdown. How much improvement is possible awaits further investigation.PART I: INTERACTION BETWEEN MICROWAVES AND THE ATMOSPHERE 1. OVERVIEW At sufficiently high power, microwave pulses propagating through the atmosphere shake the free electrons enough to ionize the surrounding air, making more free electrons, so that a plasma is created. If the ionization rate multiplied by the pulse duration is much greater than 1, the density of free electrons increases greatly during a single pulse. Equivalently, the plasma frequency increases. Depending on the density of neutral species and other factors to be discussed, this increase threatens severe attenuation of the microwave pulse, even with the plasma frequency below the carrier frequency. If the plasma frequency exceeds the carrier frequency, the latter part of the microwave pulse cannot propagate at all; it is reflected. Additional newly found features that will not be discussed here are mentioned by Goldstein.2 In addition to these effects, a target entering the atmosphere at high velocity can induce a plasma frequency above the carrier frequency, excluding the microwave beam from part or a...

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“…Yee, et al, established a fluid model and developed a set of self-consistent equations to study the HPM propagation problems in the atmosphere. [11][12][13] Liao et al, introduced a modified electron energy distribution function (EEDF) into the fluid model that improved the accuracy of the model. 14,25 In this paper, we extend the fluid model with a modified EEDF to a 3-D model in order to simulate a simplified plasma limiter prototype.…”

Section: Introductionmentioning

confidence: 99%

A fluid model simulation of a simplified plasma limiter based on spectral-element time-domain method

et al. 2015

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A simplified plasma limiter prototype is proposed and the fluid model coupled with Maxwell's equations is established to describe the operating mechanism of plasma limiter. A three-dimensional (3-D) simplified sandwich structure plasma limiter model is analyzed with the spectral-element timedomain (SETD) method. The field breakdown threshold of air and argon at different frequency is predicted and compared with the experimental data and there is a good agreement between them for gas microwave breakdown discharge problems. Numerical results demonstrate that the two-layer plasma limiter (plasma-slab-plasma) has better protective characteristics than a one-layer plasma limiter (slab-plasma-slab) with the same length of gas chamber. V C 2015 AIP Publishing LLC.

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Theory of intense electromagnetic pulse propagation through the atmosphere

Cited by 84 publications

References 11 publications

High power microwave surface flashover seed electron production methods

High power microwave surface flashover seed electron production methods

<title>Designing a high-power array for a target in the upper atmosphere</title>

A fluid model simulation of a simplified plasma limiter based on spectral-element time-domain method

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