High Altitude Nuclear Burst Research Articles

FDTD propagation of VLF-LF waves in the presence of ions in the earth-ionosphere waveguide

The finite-difference time-domain (FDTD) method has been used for a long time to compute the propagation of very low frequency (VLF) and low frequency (LF) radio waves in the Earth-Ionosphere waveguide. In previously published FDTD schemes, only the electronic density of the ionosphere was accounted for, since in usual natural conditions the effect of the ion density can be neglected. In the present paper, the FDTD scheme is extended to the case where one or several ion species must be accounted for, which may occur in special natural conditions or in such artificial conditions as after high altitude nuclear bursts. The conditions that must hold for the effect of the ions not to be negligible are discussed, the FDTD scheme with ions is derived, and numerical experiments are provided to show that the effect of the ions may be significant when the ionosphere is disturbed by incident flows of γ or β rays.

Conservative media sustain alarm about a possible electromagnetic-pulse catastrophe

<xhtml:span xmlns:xhtml="http://www.w3.org/1999/xhtml" xml:lang="en"><em>National Review</em> and others emphasize an “existential threat” in an EMP from a high-altitude nuclear burst—but solar activity stirs the fear too.</xhtml:span>

고고도핵폭발 전자기펄스 피해 분석을 위한 전산모사 연구

This paper describes computer simulation program of high-altitude electromagnetic pulse (HEMP). The HEMP is produced by the gamma rays form high-altitude nuclear explosion. The gamma rays generate a current of compton electron that leads to the production of electromagnetic fields. In case of high altitude nuclear burst, the electrical fields at the earth's surface are strong enough to be damaged for electrical and electronic device over a very much larger area. Therefore, national infrastructure will be serious damage such as power grid and communication network. In this paper introduce simulation program for calculation of HEMP and present to simulation study results of high altitude nuclear explosion experiment from U.S. and U.S.S.R.

Numerical simulation of the ionization effects of low-and high-altitude nuclear explosions

Low-altitude and high-altitude nuclear explosions are sources of intensive additional ionization in ionosphere. In this paper, in terms of the ionization equilibrium equation system and the equation of energy deposition of radiation in atmosphere, and considering the influence of atmosphere, the temporal and spacial distribution of ionization effects caused by atmospheric nuclear detonation are investigated. The calculated results show that the maximum of additional free electron density produced by low-altitude nuclear explosion is greater than that by the high-altitude nuclear burst. As to the influence of instant nuclear radiation, there is obvious difference between the low-altitude and the high-altitude explosions. The influence range and the continuance time caused by delayed nuclear radiation is less for the low-altitude nuclear detonation than that for the high-altitude one.

NUCLEAR MAGNETOHYDRODYNAMIC EMP, SOLAR STORMS, AND SUBSTORMS

In addition to a fast electromagnetic pulse (EMP), a high altitude nuclear burst produces a relatively slow magnetohydrodynamic EMP (MHD EMP), whose effects are like those from solar storm geomagnetically induced currents (SS-GIC). The MHD EMP electric field E≲10−1 V/m and lasts ≲102 sec , whereas for solar storms E≳10−2 V/m and lasts ≳103 sec . Although the solar storm electric field is lower than MHD EMP, the solar storm effects are generally greater due to their much longer duration. Substorms produce much smaller effects than SS-GIC, but occur much more frequently. This paper describes the physics of such geomagnetic disturbances and analyzes their effects.

Electromagnetic signal processing An estimation/identification application

The response of an object subjected to high energy, transient electromagnetic fields sometimes called an electromagnetic pulse (EMP) is an important issue in the survivability of electronic systems (e.g. aircraft, computer systems, etc.), especially when the field has been generated by a high-altitude nuclear burst. The characterization of transient response information is a matter of national concern. In this paper, estimation and identification techniques are applied to: (1) improve signal processing at a test facility, and (2) parameterize a particular object response. First, the application of identification-based signal processing techniques to improve signal levels at the Lawrence Livermore National Laboratory (LLNL) Electromagnetic Test Facility is discussed. Models of test equipment are identified and then utilized in processing schemes to enhance or recover the desired signals. Parametric models of objects under test are identified from the enhanced data in order to extrapolate responses to threat levels.

Effect of the Fast Nuclear Electromagnetic Pulse on the Electric Power Grid Nationwide: A Different View

This paper primarily considers the potential effects of a single high-altitude nuclear burst on the U.S. power grid. A comparison is made between EMP and natural phenomena such as lightning. This paper concludes that EMP is no more harmful to the power grid than its counterparts in natuire. An upper limit of the electric field of the very fast, high-amplitude EMP is derived from first principles. The resulting values are significantly lower than the commonly presented values. Additional calculations show that the ionization produced by a nuclear burst severely attenuates the EMP.

Identification of Electromagnetic Object Response From Noisy Transient Measurements

The response of an object subjected to high energy, transient electromagnetic (EM) fields called an electromagnetic pulse (EMP) is an important issue in the survivability of electronic systems (e.g., aircraft), especially when the field has been generated by a high altitude nuclear burst. The characterization of transient reponse information is a matter of national concern. In this paper we apply identification techniques to : (i) improve signal processing at a test facility, and (ii) parameterize a particular object response.First, we discuss the application of identification-based signal processing techniques to improve signal levels at the Lawrence Livermore National Laboratory (LLNL) Electromagnetic Test Facility. We identify models of test equipment and then use these models to deconvolve the input/output sequences from the noisy measurements for the object under test. A parametric model of the object is then identified from this data. The model is then used to extrapolate the response to the threat level EMP.

Geomagnetically trapped radiation

T magnetic field of the earth is similar to that of a dipole and can contain large numbers of trapped charged particles in its magnetic bottlelike configuration. This had been recognized for some time (see, e.g., Singer) before the discovery was made in 1958 by Explorers I and III of naturally occurring trapped particles, subsequently called Van Alien radiation. Since then, additions to the natural population of the trapped particle region have been made in the form of energetic electrons released by high-altitude nuclear bursts.' A major objective of this report is to provide a comprehensive description of the trapped charged-particle environment that can be used to find the radiation doses to which a vehicle will be exposed. The second and third sections contain a description of the trapped radiation environment, including a discussion of the sources and loss mechanisms and the dynamics of the particle motions, a description of the sources of the data and the compilation techniques, and graphic displays of the fluxes. The fourth section presents the fluxes and energy spectra integrated over sample trajectories.

A model for the generation of magnetohydrodynamic waves by high-altitude nuclear bursts

A model for the debris motion promptly following a high-altitude nuclear detonation is taken to be a perfectly conducting sphere expanding at constant velocity into a magnetoplasma, pushing the magnetic field aside, and then abruptly stopping. Representing the electromagnetic properties of the magnetoplasma by a dielectric sensor, Maxwell's equations can be written as two coupled equations for the isotropic and anisotropic modes of propagation. Using a perturbation expansion, these equations can be solved for the two modes as a function of the debris expansion velocity, which can in turn be related to the yield-to-mass ratio of the bomb. The analyses permit evaluation of the amplitude, the spatial and temporal dependence, and the frequency content of the hydromagnetic signal generated by the explosion. The model also yields a physical interpretation of that portion of the hydromagnetic yield that does not appear as radiation and allows evaluation of the efficiency of the system as a radiator of hydromagnetic waves.

Geomagnetic fluctuations due to impulse sources with applications to high-altitude nuclear bursts

The response of the ionosphere-exosphere system to a bomb-like hydromagnetic source and the resultant time-dependent ground-level magnetic fluctuations are examined theoretically in this paper, with emphasis placed upon gaining an understanding of the time behavior of the ground-level signal. The methods of calculation are also applicable to certain magnetic fluctuations of natural origin. An analytic treatment is used, whereby the problem is reduced essentially to finding the poles and residues of previously derived hydromagnetic transmission coefficients. Conditions corresponding to high magnetic latitudes are used, but some conclusions corresponding to more general conditions are drawn. Bomb-induced ground-level magnetic fluctuations are interpreted in terms of a broadband excitation of ionospheric and exospheric resonant oscillations. Even for broadband sources, which excite all of the many resonances, the signal rapidly becomes dominated by the lowest characteristic frequencies. Thus, for a wide range of source functions, the frequency content of the transmitted signal would be determined largely by the resonant properties of the propagation medium. Two examples of this are the magnetic fluctuations measured after the Argus and Starfish high-altitude nuclear tests. For hypothetical high-latitude bursts detonated in or above the lower ionosphere, the ground-level signal is predicted to be nearly left-hand circularly polarized in the daytime and to exhibit nearly the polarization of the source at night. For many situations of practical interest, the enhancement of the lower ionospheric ionization density by bomb X rays is a very important consideration.

VLF phase perturbations produced by the Soviet high-altitude nuclear explosion of November 1, 1962

The Soviet high-altitude nuclear burst of 0912 UT on November 1, 1962, produced delayed perturbations of the VLF transmissions monitored at APL/JHU over five paths remote from the burst region. The burst-related VLF effects varied from 6 to 55% and averaged 32% of the normal diurnal variation. It is suggested that the VLF phase perturbations are produced by particles from the burst that drift to the remote regions and produce an ionization enhancement in the lower ionosphere in their first, and sometimes in their second, global orbit. The temporal histories of the VLF phase perturbations are compatible with a model wherein it is assumed that the trapped particles are electrons from the radio-active decay of neutrons, the artificial belt extending from an outer shell of L ≈ 3.4 to at least L = 1.9. Satellite particle data do not show an artificial belt of electrons from the decay of neutrons, a belt which in this case may have been obscured by the background flux of electrons from the natural Van Allen belt and from the artificial belts from the earlier Soviet explosions. Satellite data do, however, show a narrow belt of fission electrons ≳1 Mev with maximum flux at L ≈ 1.77 and a lower boundary at L = 1.73. These fission electrons did not affect the VLF paths intercepted by these shells. The VLF and satellite data agree that fission electrons ≳1 Mev were not present on shells above L ≈ 1.9.

Geomagnetically Trapped Radiation

T magnetic field of the earth is similar to that of a dipole and can contain large numbers of trapped charged particles in its magnetic bottlelike configuration. This had been recognized for some time (see, e.g., Singer) before the discovery was made in 1958 by Explorers I and III of naturally occurring trapped particles, subsequently called Van Alien radiation. Since then, additions to the natural population of the trapped particle region have been made in the form of energetic electrons released by high-altitude nuclear bursts.' A major objective of this report is to provide a comprehensive description of the trapped charged-particle environment that can be used to find the radiation doses to which a vehicle will be exposed. The second and third sections contain a description of the trapped radiation environment, including a discussion of the sources and loss mechanisms and the dynamics of the particle motions, a description of the sources of the data and the compilation techniques, and graphic displays of the fluxes. The fourth section presents the fluxes and energy spectra integrated over sample trajectories.

Very low frequency phase perturbations and the Soviet high-altitude nuclear bursts of October 22 and 28, 1962: 2. Comparison with satellite particle data

Energy and spatial characteristics of artificial radiation belts were deduced in part 1, where we examined the temporal histories of the VLF phase perturbations produced by the two Soviet high-altitude nuclear bursts of October 1962. For both bursts the trapped electrons have energies ≲4 Mev, the electron spectrum ≲0.78 Mev resembling that from the radioactive decay of neutrons. This dichotomy of fission and neutron-decay β particles in the electron spectrum has not been achieved in the satellite particle data so far analyzed, where the energy ranges are either too broad or above 0.78 Mev. For the burst of October 22, the VLF characteristic that electrons ≲4 Mev are trapped in the region encompassing at least 1.75 ≲ L ≲ 3.76 is compatible with the trapped particle flux observed by Explorer 14, Alouette, and Telstar 1. For the burst of October 28, the VLF shows that fission β particles ≳0.78 Mev are not present in L > 2.32 and are confined on shells 1.6 Mev or the Explorer 15 results for electrons >1.9 Mev. The Alouette results also show that the energy spectrum extends to about 10 Mev, but that there is a rapid decrease in flux for E > 4 Mev. For the burst of October 28, the VLF shows that neutron-decay β particles have an outer trapping boundary at 2.32 ≤ L 230 kev but not with the Telstar data for E > 390 kev, where the outer boundary extends to L ∼ 4. The VLF result that protons 2.3 500 kev at L = 2.8 and 3.2. The characteristics of protons from nuclear explosions are reviewed, and the electron results are consolidated to form at least a model for additional investigations of the artificial radiation belts formed by the Soviet bursts of October 22 and 28, 1962.

Very low frequency phase perturbations and the soviet high-altitude nuclear bursts of October 22 and 28, 1962: 1. Observations and inferred radiation belts

On October 22 and 28, 1962, nuclear explosions over central Asia produced ionospheric D-layer perturbations as monitored on various VLF paths in the northern hemisphere. Delayed VLF effects due to trapped particles averaged 53% of the normal diurnal change for the burst of October 22, and 29% for the burst of October 28. The types of particles and their energies were the same for both detonations, but differences existed in the spatial extent of the radiation belts producing the VLF phase perturbations. The trapped particles were electrons with E ≲ 4 Mev and protons in the range 2.3 to 4.6 Mev. The electron spectrum is composed of fission and neutron-decay β particles, the latter predominating for E < 0.78 Mev. Protons <2.3 Mev may have also been present, but those with E < 1 Mev cannot penetrate into the D region and are of no direct VLF interest. With the dipole field approximation, for the detonation of October 22, fission and neutron-decay β particles were trapped in a region bounded by field lines intersecting the earth's surface in a range extending at least from 36.5° to 56° geomagnetic (for the real field the shells are 1.75 ≤ L ≤ 3.76). For October 28, fission β particles were confined to areas <49°N (L < 2.32) and probably to field lines around that passing through the burst point (at 36.5°N and L = 1.75); this type of confinement also existed for 2.3- to 4.6-Mev protons after both nuclear bursts. For October 28, effects due to neutron-decay β particles were found at 49°–51°N (2.32 ≤ L ≤ 2.79), a region which formed the outer boundary for these trapped particles. For the burst of October 22, a prompt effect was observed on the GBR to APL transmission.

A note on persisting radio propagation effects after high altitude nuclear bursts

In 1958 the United States detonated two megaton-range nuclear devices, one (Teak) at 252,000 feet and the other (Orange) at 141,000 feet over the vicinity of Johnston Island [U.S. Government Printing Office, 1962]. For several days after each burst anomalous propagation effects were observed in the general area. Samson [1960] has pointed out that radio noise data obtained in Hawaii showed that the LF and VLF regions were particularly affected. The greatest effect was a reduction in the nighttime noise intensity for several nights following the detonations.

An analog method for determining neutron shadow-cone geometry for high-altitude nuclear tests

The purpose of this letter is to describe an analog method for studying neutron shadowcone geometry associated with high-altitude nuclear tests and to demonstrate some of the results obtained using this technique. As early as 1958, it was observed that high-altitude nuclear bursts are capable of producing sudden changes in VLF and HF propagation even along radio paths which are well beyond the line of sight range to the detonation point.

Another possible explanation of sudden atmospheric lonization in regions shadowed from high-altitude nuclear bursts

Sudden changes in VLF propagation characteristics, presumably due to increased D-layer ionization, have been observed to occur along VLF paths whose nearest points lie thousands of kilometers away from a high-altitude nuclear burst. It is proposed that this ionization may be caused by neutrons that have been transported by multiple scatterings around the earth and well into the shadow zone where they deposit part of their kinetic energy through collisions with nitrogen nuclei. Numerical results are presented which, though based on a highly simplified model problem, encourage further detailed calculations. The possibility of observationally distinguishing between the transport mechanism and the neutron decay mechanism is also discussed.

Satellite measurements of the decay of the artificial electron belt

Measurements of the radiation environment have been made with dosimetry films and activation materials flown on a series of low-altitude satellites. In orbits with about 400-km apogee, the electrons injected by the high-altitude nuclear burst of July 9, 1962, increased the average daily radiation dose by a factor of 1000 over the normal 0.01 rad from cosmic rays. The apparent half-life for disappearance of the artificial electron belt in the lower regions of the South American anomaly was initially less than 10 days and lengthened to more than 100 days in the first 9 months after the burst. Evidence confirming the identification of the radiation type was provided by depth-dose curves, obtained with Al, Pb, and other absorbers, which were similar to theoretical curves derived for fission electrons. The observation that zenith-side doses were 2 to 5 times greater than earth-side doses is consistent with the expected direction of approach of trapped electrons to the satellite in the region of the South American anomaly. No activation caused by space protons or neutrons was observed in any of the activation materials.

On geomagnetic fluctuations in regions remote from high-altitude nuclear bursts

It is the purpose of this letter to suggest that ionospheric ionization caused by β particles resulting from the decay of detonation-produced neutrons is capable of causing an artificial geomagnetic solar-flare effect [McNish, 1937] in regions several thousands of kilometers from a high-altitude nuclear burst. Although geomagnetic fluctuations due to a bomb-produced solarflare effect were noted in the Pacific after the Hardtack detonations [McNish, 1959], we refer here to smaller disturbances occurring much farther from the bursts. The concepts advanced in a paper by Crain and Tamarkin [1961], which should be consulted for an explanation of much of what follows, are used to make estimates about the characteristics of this effect. Comparisons with some experimental results are also made.