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, abbreviated
EMP transient with the essential property in a very short time to a certain maximum value to rise and then fall off relatively slowly to the steady resting level.
is usually on the importance of the concept of electrical systems relevant pulse spectra reduced, ie wavelengths between 10 mm and 10 km.
/ /
definition is pulse in this context present in the concept of
physical [ Edit
]The term
confused in the field of mechanics
T continuously repeated, it is called a . a physical characteristic such as field strength, voltage or pressure represented. If a pulse with the period
Mathematics is a pulse as a one-time
function f (t) f = 1 / T
. This definition mirrors the concept of German literature, is particularly directed to on Electromagnetic Theory by Karl
Küpfmüller. (See literature source)
harmonic vibrations. For a pulse requires a continuous superposition of harmonic Schwingungen.
Quellen elektromagnetischer Impulse und ihre Auswirkungen
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[ , welche zu einer massiven elektromagnetischen Beeinflussung nicht nur im Bereich des Blitzkanals und des Einschlagpunktes führen, sondern auch in weit davon entfernten elektrischen Leitungen und Geräten. Der durch Influenz und Magnetfelder ausgelöste elektromagnetische Impuls wird auch LEMP (engl. Lightning Electromagnetic Pulse) genannt. Weitere Informationen finden sich im Artikel Blitz .
Magnetohydrodynamischer EMP
Dieser Impuls mit einer vergleichsweise langen Dauer, im Bereich von Sekunden bis zu einigen Minuten, wird durch natürliche thermische Ausgleichsvorgänge in der Erdatmosphäre ausgelöst. Ursache ist eine Wechselwirkung zwischen dem Erdmagnetfeld und ionisierten Gasmassen in der Erdatmosphäre.
This impulse can occur for inductive coupling of low frequency currents in spatially extended over a large area power supply networks, which can lead for example to saturation in power transformers. This could result in power outages
.[edit ] When spark discharge electrostatically charged body resulting transient voltages and currents associated with transient electric and magnetic fields, which produce an electromagnetic pulse. the operations and counter-measures are grouped under the term ESD . By such discharges, it may come to damage or destroy electronic components.
For testing purposes, such operations can discharge human by high-voltage capacitors
body model). Depending on the coupling network and size of the capacitor can vary strong pulses or waveforms are generated for testing purposes. be generated. For this, a capacitor charged to the test voltage and then a defined resistance in the tested component or discharged. It simulates the operation of a component by an electrostatically charged person (Switched inductors [ Edit
]Due to high current pulses in the coil can generate powerful electromagnetic pulses. Examples are magnetic coils to study the effect of high magnetic fields on matter that can be reused in fields up to about 100 Tesla
be destroyed at higher fields, however. For mechanical protection and magnetic shielding, appropriate Labore in dicken Eisenbetongebäuden untergebracht. Die durch Kondensatorentladung erzeugten Stromimpulse erreichen einige 100 Kiloampere, die Dauer liegt im Bereich von Millisekunden.In Railguns und Wirbelstrombeschleunigern liegen ähnliche Verhältnisse vor.
Durch Impuls-Teslatransformatoren werden hohe elektromagnetische Felder im Mittelwellenbereich erzeugt. Auch das Abschalten von Induktivitäten führt zu elektromagnetischen Impulsen. Durch das Bestreben des elektrischen Stromes, beim Ausschaltvorgang weiter durch die Induktivität fließen zu wollen, entstehen an der Spule very high voltages, which can lead to arcing. The glitches spread out on lines, causing signal interference and may have similar effects such as electrostatic discharges. Such pulses occur for example during the switching of electric motors , shooters and other inductive components on. A common source of interference of this kind is the ignition system of petrol engines, in which the effect of voltage rise, however, is like a
induction coil used.nuclear electromagnetic pulse (NEMP) [ Edit
]A nuclear electromagnetic pulse, abbreviated
NEMP (English Nuclear Electromagnetic Pulse) is indirectly as a result of intense gamma radiation in some 100 km above the Earth's atmosphere in connection with the Earth's magnetic field in the atmosphere through the so-called Compton effect triggered. Such a strong transient gamma-ray source is produced only by a nuclear explosion to .
By ban aboveground nuclear weapons tests such explosions took place and actually damaged or destroyed in the affected Areas networks and ships, when nuclear weapons test
Starfish Prime above the Pacific on 9 July 1962. comes through high-energy gamma rays in the range of a few MeV
up there at themolecules the top layers of the atmosphere to a sudden ionization: These are ejected from the molecule electrons so-called primary electrons, of which a large share retains the original direction of gamma quantum and the direction of denser layers of the atmosphere is moving. A portion of these free electrons caused due to high energy as a result more
impact ionization and thereby releases more so-called secondary electrons. The flying towards the earth negative electrons and the remaining positive air ions form a transient electric dipole. Due to the deflection of the moving charge carriers in the Earth's magnetic field as a result of the Lorentz force it creates a transient magnetic dipole.
This temporally and spatially rapidly varying charge and current distribution of the dipoles generated in the upper atmosphere, a broadband, transient wave field, which only gives the actual electromagnetic pulse for impairment of electronic devices und elektrischen Anlagen verantwortlich ist. Ein NEMP ist im Unterschied zum LEMP durch die besonders steile Anstiegsgeschwindigkeit und somit Breitbandigkeit gekennzeichnet. Bereits nach 4 ns werden 90 % des Maximalwerts erreicht.
Der genormte NEMP, wie er in Prüflaboratorien zum Prüfen von Abschirmungen verwendet wird, weist als Maximalwert eine elektrische Feldstärke von 50 kV/m und eine magnetische Feldstärke von 133 A/m auf.
Ähnliche Effekte treten auch bei nuklearen Explosionen in Bodennähe auf. Dort ist die Wirkung des NEMP allerdings auf einen kleineren räumlichen Bereich beschränkt und durch die thermischen und mechanischen Effekte nuclear explosion superimposed.An effect similar to a NEMP can also be triggered by strong gamma-ray bursts of natural origin, for example by pulsars or gamma-ray bursts when the earth are close enough and their gamma-ray light cone coincidentally meets the earth, so that the intensity of gamma radiation is strong enough. The probability is very low, because the time is not sufficiently close pulsar known, and gamma-ray bursts are indeed quite commonly observed, however, connect to the entire observed universe to spread and thus are extremely within the solar neighborhood rare. Also exists in the immediate solar neighborhood does not object, as that by today's standards as a source of a gamma-ray burst may be considered.
[Edit ] electromagnetic pulses, electrical and destroy mainly electronic components in the effective range and therefore the military and in the form of ground-based EMP weapons used (see also: electronic warfare
,E-bomb , induction ). As a radiation source for this is, for example, the microwave radiation directed of relativistic magnetron which, fed by supply capacitors, excellence in Terawattbereich .
laser radiation [edit ]
too strong laser pulses trigger in the interaction with matter, an EMP. Laboratories for research purposes with laser radiation powers up to the Petawattbereich therefore have a radiation protection and other appropriate measures to protect communications networks.
Protection against EMP is the encapsulation of the devices in a Faraday cageand appropriate protection circuits ( Isolation , surge suppressors) are available on all electric supply lines. In radio equipment, the shielding can be achieved, however imperfectly, as their antennas can not be shielded and direct the electromagnetic fields inside.
spatially wide-spread electrical conductors, such as energy supply and copper telecommunications networks, sind vor allem durch LEMP bzw. NEMP gefährdet. Metallene Rohrleitungen sind auch durch NEMP gefährdet. Während Energieversorgungsnetze kaum geschützt werden können, kann man in Kommunikationsleitungen Trennübertrager oder -verstärker einbauen oder sie durch Glasfasernetze ersetzen. Rohrleitungen kann man zum Schutz stellenweise oder ganz aus isolierenden Werkstoffen herstellen.Hausinstallationen (Energie und Kommunikation) lassen sich mit einigem Aufwand durch geeignete Erdung und Überspannungsableiter schützen.
Der elektromagnetische Puls kann als
Waffe oder für Anschläge benutzt werden und dann auch außergewöhnlich schwere Folgen have (see: third risk report
Protection Commission to the Federal Minister of the Interior, Bonn 2006, p. 30-32, 86, 90).
literature ]Adolf J. Schwab: Electromagnetic Compatibility, 4 Edition, Springer Verlag, ISBN 3-540-60787-0
Karl Küpfmüller: Theoretical Electrical and Electronics 14 Edition, Springer Verlag, ISBN 3-540-56500-0 Johannes Wilhelm ea: nuclear electro-magnetic pulse (NEMP): origin, safeguard measures, measurement , Volume 110, expert-Verlag, ISBN 3-88508-929-7
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