Electromagnetic Pulse Environment Research Articles

Development of gated fiber detectors for laser-induced strong electromagnetic pulse environments

With the development of laser technologies, nuclear reactions can happen in high-temperature plasma environments induced by lasers and have attracted a lot of attention from different physical disciplines. However, studies on nuclear reactions in plasma are still limited by detecting technologies. This is mainly due to the fact that extremely high electromagnetic pulses (EMPs) can also be induced when high-intensity lasers hit targets to induce plasma, and then cause dysfunction of many types of traditional detectors. Therefore, new particle detecting technologies are highly needed. In this paper, we report a recently developed gated fiber detector which can be used in harsh EMP environments. In this prototype detector, scintillating photons are coupled by fiber and then transferred to a gated photomultiplier tube which is located far away from the EMP source and shielded well. With those measures, the EMPs can be avoided which may result that the device has the capability to identify a single event of nuclear reaction products generated in laser-induced plasma from noise EMP backgrounds. This new type of detector can be widely used as a time-of-flight (TOF) detector in high-intensity laser nuclear physics experiments for detecting neutrons, photons, and other charged particles.

Design of a Shielded Core Current

Aiming at the problem that the signal noise ratio (SNR) can’t meet the requirement due to electromagnetic interference in the measurement of coupling current of transmission cable core line in electromagnetic pulse environment, a shielded core line pulse current probe is designed and developed. This paper introduces the measuring principle of the probe, the structure characteristics and development situation, given the characteristics of the probe sensitivity and parameters, such as spectrum method and the calibration parameters, and analyzes its usage in the experimental results show that the design of shielded conductor pulse current probe based on the structure of the original transmission has a better ability to resist electromagnetic interference and pulse signal measurement capability.

Experiment research on electromagnetic pulse effects of typical nuclear security system

High-altitude electromagnetic pulse(HEMP) is a kind of transient electromagnetic wave which can be coupled into various electronic and electrical equipments through field lines or holes. To ensure that the security system of key departments can work normally under the electromagnetic pulse environment, it is necessary to carry out the electromagnetic pulse effect test against the security system, and analyze the weak link and survival ability of this kind of system under the electromagnetic pulse environment. According to the topology of nuclear security system, the electromagnetic pulse radiation test and pulse current injection test platform are set up, and the threshold and effect phenomena of the key components of the nuclear security system are obtained through the test. Furthermore, the failure mechanism of key components is analyzed based on the circuit principle of each component, and the weak link of typical nuclear security system is summarized, which provide data support for the protection and reinforcement design of the follow-up security system.

激光惯性约束聚变装置靶室内电磁脉冲环境的理论研究

激光惯性约束聚变装置靶室内电磁脉冲环境的理论研究

CCD成像设备在强电磁脉冲环境下的效应实验研究

CCD成像设备在强电磁脉冲环境下的效应实验研究

美军有关核电磁脉冲研究的指令、指示、标准及试验操作规程

核环境中武器装备的生存能力研究是美军的一项重要工作，抗核电磁脉冲防护是其中一项重要内容。美军很早就在这一领域开展了相关研究，并取得了丰富的成果。为了指导相关工作开展，美军颁布了较为系统的指导性、技术性文件。本文主要介绍了美军有关核电磁脉冲的指令性文件、环境与效应要求、加固/防护标准、试验标准、电磁脉冲环境下武器系统生存能力试验操作规程。 Research on arms and equipment survivability in nuclear environment is an important work of the U.S. military, and nuclear electromagnetic pulse protection is a main part of this work. The U.S. military started studying these problems since many years ago, and made a great progress. In order to guide this research, the U.S. military issued series of documents about electromagnetic pulse, just like DoD Directives, DoD Instructions, environment & effects requirements, hardening/protect standard, test standard, arms and equipment survivability test operations procedure in nuclear electromagnetic pulse environment. They are all introduced in this article.

Early-time high-altitude electromagnetic pulse environment (E1) simulation with a bicone-cage antenna

The simulation of the early-time High-altitude Electromagnetic Pulse (HEMP) environment (E1) with bicone-cage antenna in free space requires utilization of the spherical wave to reproduce the boundless plane wave. The transient radiation of the antenna above the lossy ground is computed using the Finite-Difference Time-Domain (FDTD) method. The determining factors of the field waveform are explored and analysed on the basis of the physical evolution process of the transient radiation. The typical waveform of the electric field and the field distribution characteristics, both of which are important for HEMP simulator design and the effect tests, are presented. The study indicates that the simulation should be analysed from the perspective of both environment building and simulator applications.

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10(8) DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10(4) per shot and up to 10(11) neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields (∼10(11)). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6×10(-4) was used. The combined use of all three detectors allowed for a detection range of 10(4) to 10(11) neutrons per shot.

Electromagnetic pulse environment of cloud-to-ground lightning for EMC studies

The characteristics of lightning electromagnetic pulse (LEMP) from individual processes in lightning such as return strokes, preliminary breakdown pulses, pulses associated with the leader process, K-changes and M-changes, the isolated narrow bipolar pulses, and the pulse bursts have been known. However, there is a need for a combined characterization of the total LEMP environment created during the entire duration of lightning. An attempt is made to provide such a description that gives the distribution of the LEMP characteristics, which is important in its ability to interfere with electronic systems, such as peak amplitude, peak time derivative, pulse duration, number of pulses, and time interval between pulses, during the entire duration of a cloud-to-ground lightning. Separate electromagnetic environment characterizations for negative cloud-to-ground lightning and positive cloud-to-ground lightning are proposed, including all the significant LEMP sources. Based on the LEMP characterization, models for negative and positive cloud-to-ground lightning flashes, that could be used in electromagnetic compatibility (EMC) studies are proposed. The electromagnetic environment models for cloud-to-ground lightning can be coupled to the locations of lightning given by the lightning location system to give comprehensive information about the electromagnetic environment at a desired geographical location.

Impacts of a nominal nuclear electromagnetic pulse on electric power systems: a probabilistic approach

Since 1983, the US Department of Energy has been actively pursuing a research program to assess the potential effects of one or more electromagnetic pulse (EMP) events on the nation's electric energy supply. A nominal EMP environment suitable for assessing geographically large systems has been used to provide an indication of EMP effects on electric power systems. It was found that a single high-altitude burst, significantly disturbs the geomagnetic field, could cause significant load and generation loss, but permanent damage would be isolated. Multiple bursts would increase the disturbance. Nevertheless, based on the effects of a nominal EMP environment, a long-term blackout is not expected since major components such as power transformers are not likely to be damaged.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Theoretical considerations for optimal positioning of peaking capacitor arms about a Marx generator parallel to a ground plane

The authors develop theoretical considerations useful in determining the electromagnetically optimal positions for a specified number of peaking-capacitor arms about a Marx generator parallel to a ground plane. It is shown that this can be determined by a conformal transformation. A parameter is defined and computed that is indicative of the effectiveness of the peaking-capacitor arms in shielding the Marx from the ground plane. The results of interest in connection with determining the hardness of systems to a nuclear electromagnetic pulse environment. >

Development of a New High Altitude Electromagnetic Pulse (Hemp) Environment and Resulting Overhead Line Responses

Being able to accurately determine the response of an electrical system which is excited by a high altitude nuclear electromagnetic pulse (EMP) requires a knowledge of the time history of the incident EMP field strength, as well as its angle of incidence and polarization. A commonly used, unclassified, description of this environment is provided by the ''Bell Laboratory waveform.'' Recent studies have shown, however, that this EMP waveform tends to overestimate the response of an above-ground transmission line by more than an order of magnitude. As a result, other unclassified high altitude EMP environments have been developed. This presentation discusses the development of two alternate unclassified EMP environment descriptions: one arising from a simple radiating dipole moment model, and the other resulting from curve-fitting the calculated fields from a computer code named CHAP. For both of these EMP models, the electric field at two earth observation points are compared. These fields are then coupled to an above-ground line and the resulting open-circuit voltage responses are compared. Using the CHAP EMP environment, a limited parametric study of the peak positive and negative open-circuit voltage is then performed and surface plots of these peak voltages are presented. 8 refs., 21 figs., 1more » tab.« less