Plasma speakers or ionophones are a form of loudspeaker which varies air pressure via an electrical plasma instead of a solid diaphragm . The plasma arc heats the surrounding air causing it to expand. Varying the electrical signal that drives the plasma and connected to the output of an audio amplifier , the plasma size varies which in turn varies the expansion of the surrounding air creating sound waves.
19-403: Plasmatronics is a company, founded by former Air Force Weapons Laboratory (now Phillips Laboratory) scientist Dr. Alan E. Hill , which produced a plasma speaker design. This was first demonstrated at the 1978 Winter Consumer Electronics Show . The product used a conventional dynamic loudspeaker with an integrated amplifier for low frequencies. For a tweeter it used a plasma speaker as
38-425: A New York-based company, both offered their own variant of the plasma speaker as a DIY kit. The ExcelPhysics variant used a flyback transformer to step up voltage, a 555 timing chip to provide modulation and a 44 kHz carrier signal , and an audio amplifier. The kit is no longer marketed. A flame speaker uses a modulated flame for the driver and could be considered related to the plasma loudspeaker. This
57-611: A commercial plasma speaker that used a helium tank to provide the ionization gas. In 1978 Alan E. Hill of the Air Force Weapons Laboratory in Albuquerque, NM, designed the Plasmatronics Hill Type I , a commercial helium-plasma tweeter. This avoided the ozone and nitrogen oxides produced by radio frequency decomposition of air in earlier generations of plasma tweeters. But the operation of such speakers requires
76-624: A continuous supply of helium. In the 1950s, the pioneering DuKane Corporation produced the air-ionizing Ionovac , marketed in the UK as the Ionophone . Currently there remain manufacturers in Germany who use this design, as well as many do-it-yourself designs available on the Internet. To make the plasma speaker a more widely available product, ExcelPhysics, a Seattle-based company, and Images Scientific Instruments,
95-452: A massless radiating element. The technique is a much later development of physics principles demonstrated by William Duddell 's "singing arc" of 1900, and Hermann Theodor Simon published the same phenomenon in 1898. The term ionophone was used by Dr. Siegfried Klein who developed a plasma tweeter that was licensed for commercial production by DuKane with the Ionovac and Fane Acoustics with
114-415: A near-massless driver . Uniquely, to prevent ozone and NOx emissions it sourced helium from a tank in the back of the unit. While praised for accurate sound reproduction at demonstrations, the system had a number of disadvantages, including high cost and periodic handling of heavy compressed helium cylinders. Plasma speaker The plasma is typically in the form of a glow discharge and acts as
133-547: A nearly ideal reproduction of the sound source when the electric or magnetic field is modulated with the audio signal. Conventional loudspeaker transducer designs use the input electrical audio frequency signal to vibrate a significant mass: In a dynamic loudspeaker this driver is coupled to a stiff speaker cone —a diaphragm which pushes air at audio frequencies. But the inertia inherent in its mass resists acceleration —and all changes in cone position. Additionally, speaker cones will eventually suffer tensile fatigue from
152-476: A plasma speaker, as member of the family of massless speakers, these limitations do not exist. The low-inertia driver has exceptional transient response compared to other designs. The result is an even output, accurate even at higher frequencies beyond the human audible range. Such speakers are notable for accuracy and clarity, but not lower frequencies because plasma is composed of tiny molecules and with such low mass are unable to move large volumes of air unless
171-480: The microwave range. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves , so they are used in radio technology, among other uses. Different sources specify different upper and lower bounds for the frequency range. Electric currents that oscillate at radio frequencies ( RF currents ) have special properties not shared by direct current or lower audio frequency alternating current , such as
190-430: The "flame". Radio frequency Radio frequency ( RF ) is the oscillation rate of an alternating electric current or voltage or of a magnetic , electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz . This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies, and also encompasses
209-504: The 50 or 60 Hz current used in electrical power distribution . The radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunication Union (ITU): Frequencies of 1 GHz and above are conventionally called microwave , while frequencies of 30 GHz and above are designated millimeter wave . More detailed band designations are given by
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#1733085903078228-455: The Ionofane in the late 1940s and 1950s. The effect takes advantage of several physical principles: First, ionization of a gas creates a highly conductive plasma, which responds to alternating electric and magnetic fields . Second, this low- density plasma has a negligibly small mass. Thus, the air remains mechanically coupled with the essentially massless plasma, allowing it to radiate
247-522: The current proliferation of radio frequency wireless telecommunications devices such as cellphones . Medical applications of radio frequency (RF) energy, in the form of electromagnetic waves ( radio waves ) or electrical currents, have existed for over 125 years, and now include diathermy , hyperthermy treatment of cancer, electrosurgery scalpels used to cut and cauterize in operations, and radiofrequency ablation . Magnetic resonance imaging (MRI) uses radio frequency fields to generate images of
266-413: The human body. Radio Frequency or RF energy is also being used in devices that are being advertised for weight loss and fat removal. The possible effects RF might have on the body and whether RF can lead to fat reduction needs further study. Currently, there are devices such as trusculpt ID , Venus Bliss and many others utilizing this type of energy alongside heat to target fat pockets in certain areas of
285-410: The plasma are in large number. So these designs are more effective as tweeters . Plasma speaker designs ionize ambient air which contains the gases nitrogen and oxygen . In an intense electrical field these gases can produce reactive by-products, and in closed rooms these can reach a hazardous level. The two predominant gases produced are ozone and nitrogen dioxide . Plasmatronics produced
304-416: The repeated shaking of sonic vibration. Thus conventional speaker output, or the fidelity of the device, is distorted by physical limitations inherent in its design. These distortions have long been the limiting factor in commercial reproduction of strong high frequencies. To a lesser extent square wave characteristics are also problematic; the reproduction of square waves most stress a speaker cone. In
323-465: The standard IEEE letter- band frequency designations and the EU/NATO frequency designations. Radio frequencies are used in communication devices such as transmitters , receivers , computers , televisions , and mobile phones , to name a few. Radio frequencies are also applied in carrier current systems including telephony and control circuits. The MOS integrated circuit is the technology behind
342-402: The transmitting antenna, where voltages in the tens of thousands volts are involved. The ionized air is heated in direct relationship to the modulating signal with surprisingly high fidelity over a wide area. Due to the destructive effects of the (self-sustaining) discharge this cannot be permitted to persist, and automatic systems momentarily shut down transmission within a few seconds to quench
361-423: Was explored using the combustion of natural gas or candles to produce a plasma through which current is then passed. These combustion designs do not require high voltages to generate a plasma field, but there has been no commercial products using them. A similar effect is occasionally observed in the vicinity of high-power amplitude-modulated radio transmitters when a corona discharge (inadvertently) occurs from
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