What is BIEFELD-BROWN EFFECT? What does BIEFELD-BROWN EFFECT mean? BIEFELD-BROWN EFFECT meaning
What is BIEFELD-BROWN EFFECT? What does BIEFELD-BROWN EFFECT mean? BIEFELD-BROWN EFFECT meaning - BIEFELD-BROWN EFFECT definition - BIEFELD-BROWN EFFECT explanation.
Source: Wikipedia.org article, adapted under https://creativecommons.org/licenses/by-sa/3.0/ license.
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The Biefeld–Brown effect is an electrical effect that produces an ionic wind that transfers its momentum to surrounding neutral particles. The effect was named by inventor Thomas Townsend Brown who claimed that he did a series of experiments with professor of astronomy Paul Alfred Biefeld, a former teacher of Brown who Brown claimed was his mentor and co-experimenter at Denison University in Ohio. The phenomenon was also given the name "electrogravitics" by Brown based on his belief this was an electricity/gravity phenomenon. The effect is more widely referred to as electrohydrodynamics (EHD) or sometimes electro-fluid-dynamics, a counterpart to the well-known magnetohydrodynamics. Extensive research was performed during the 1950s and 1960s on the use of this electric propulsion effect during the publicized era of the United States gravity control propulsion research (1955–1974).
There is renewed focus on the Biefield–Brown effect with the spread in interest in high-voltage powered experimental flying devices known as ionocraft or lifters.
The effect is generally believed to rely on corona discharge, which allows air molecules to become ionized near sharp points and edges. Usually, two electrodes are used with a high voltage between them, ranging from a few kilovolts and up to megavolt levels, where one electrode is small or sharp, and the other larger and smoother. The most effective distance between electrodes occurs at an electric potential gradient of about 10 kV/cm, which is just below the nominal breakdown voltage of air between two sharp points, at a current density level usually referred to as the saturated corona current condition. This creates a high field gradient around the smaller, positively charged electrode. Around this electrode, ionization occurs, that is, electrons are stripped from the atoms in the surrounding medium; they are literally pulled right off by the electrode's charge.
This leaves a cloud of positively charged ions in the medium, which are attracted to the negative smooth electrode by Coulomb's Law, where they are neutralized again. This produces an equally scaled opposing force in the lower electrode. This effect can be used for propulsion (see EHD thruster), fluid pumps and recently also in EHD cooling systems. The velocity achievable by such setups is limited by the momentum achievable by the ionized air, which is reduced by ion impact with neutral air. A theoretical derivation of this force has been proposed (see the external links below).
However, this effect works using either polarity for the electrodes: the small or thin electrode can be either positive or negative, and the larger electrode must have the opposite polarity. On many experimental sites it is reported that the thrust effect of a lifter is actually a bit stronger when the small electrode is the positive one. This is possibly an effect of the differences between the ionization energy and electron affinity energy of the constituent parts of air; thus the ease of which ions are created at the 'sharp' electrode.
As air pressure is removed from the system, several effects combine to reduce the force and momentum available to the system. The number of air molecules around the ionizing electrode is reduced, decreasing the quantity of ionized particles. At the same time, the number of impacts between ionized and neutral particles is reduced. Whether this increases or decreases the maximum momentum of the ionized air is not typically measured, although the force acting upon the electrodes reduces, until the glow discharge region is entered. The reduction in force is also a product of the reducing breakdown voltage of air, as a lower potential must be applied between the electrodes, thereby reducing the force dictated by Coulomb's Law.