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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Biefeld–Brown effect | 1/2 | https://en.wikipedia.org/wiki/Biefeld–Brown_effect | reference | science, encyclopedia | 2026-05-05T10:54:39.546162+00:00 | kb-cron |
The Biefeld–Brown effect () is an electrical phenomenon, first noticed by inventor Thomas Townsend Brown in the 1920s, where high voltage applied to the electrodes of an asymmetric capacitor causes a net propulsive force toward the smaller electrode. Brown believed this effect was an anti-gravity force, and referred to it as electrogravitics based on it being an electricity/gravity phenomenon. Detailed studies in vacuum chambers failed to replicate Brown's observations and follow-up studies attribute the force measure to corona wind from electrical discharge.
== Overview == It is generally assumed that the Biefeld–Brown effect produces an ionic wind that transfers its momentum to surrounding neutral particles. It describes a force observed on an asymmetric capacitor when high voltage is applied to the capacitor's electrodes. Once suitably charged up to high DC potentials, a thrust at the negative terminal, pushing it away from the positive terminal, is generated. The use of an asymmetric capacitor, with the negative electrode being larger than the positive electrode, allowed for more thrust to be produced in the direction from the low-flux to the high-flux region compared to a conventional capacitor. These asymmetric capacitors became known as Asymmetrical Capacitor Thrusters (ACT). These devices can be observed in ionocrafts and lifters, which utilize the effect to produce thrust in the air using electrical power without requiring any combustion or moving parts.
== History ==
The "Biefeld–Brown effect" was the name given to a phenomenon observed by Thomas Townsend Brown while he was experimenting with X-ray tubes during the 1920s while he was still in high school. When he applied a high voltage electrical charge to a Coolidge tube that he placed on a scale, Brown noticed a difference in the tube's mass depending on orientation, implying some kind of net force. This discovery caused him to assume that he had somehow influenced gravity electronically and led him to design a propulsion system based on this phenomenon. On 15 April 1927, he applied for a patent, entitled "Method of Producing Force or Motion," that described his invention as an electrical-based method that could control gravity to produce linear force or motion. In 1929, Brown published an article for the popular American magazine Science and Invention, which detailed his work. The article also mentioned the "gravitator," an invention by Brown which produced motion without the use of electromagnetism, gears, propellers, or wheels, but instead using the principles of what he called "electro-gravitation." He also claimed that the asymmetric capacitors were capable of generating mysterious fields that interacted with the Earth's gravitational pull and envisioned a future where gravitators would propel ocean liners and even space cars. At some point this effect also gained the moniker "Biefeld–Brown effect", probably coined by Brown to claim Denison University professor of physics and astronomy Paul Alfred Biefeld as his mentor and co-experimenter. Brown attended Denison in Ohio for a year before he dropped out and records of him even having an association with Biefeld are sketchy at best. Brown claimed that he did a series of experiments with professor of astronomy Biefeld, a former teacher of Brown whom Brown claimed was his mentor and co-experimenter at Denison University. As of 2004, Denison University claims they have no record of any such experiments, or of any association between Brown and Biefeld. In his 1960 patent titled "Electrokinetic Apparatus," Brown refers to electrokinesis to describe the Biefeld–Brown effect, linking the phenomenon to the field of electrohydrodynamics (EHD). Brown also believed the Biefeld–Brown effect could produce an anti-gravity force, referred to as "electrogravitics" based on it being an electricity/gravity phenomenon. However, there is little evidence that supports Brown's claim on the effect's anti-gravity properties. In 1965, Brown filed a patent that claimed that a net force on the asymmetric capacitor can exist even in a vacuum. However, there is little experimental evidence that serves to validate his claims. In 1988, R. L. Talley measured no thrust from electrodes similar to those proposed by Brown operating in 10−6 torr vacuum under direct current potentials. He did find a force during electrical breakdown when current was flowing. In 2004, Tajmar enclosed the electrode apparatus in a box suspended on wires which would exclude any effect of corona wind. No linear thrust was observed indicating that the Biefeld–Brown effect was the well-studied corona wind.
== Effect analysis ==