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Thread: Force Fields and 'Plasma' Shields Get Closer to Reality

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    Default Force Fields and 'Plasma' Shields Get Closer to Reality

    Force Fields and 'Plasma' Shields Get Closer to Reality
    By James Schultz
    Special to SPACE.com
    posted: 07:00 am ET
    25 July 2000

    Space-borne protective energy systems, like the deflector shields on the fictional starship U.S.S. Voyager, are on the drawing board of real-world scientists.

    These "cold plasmas" -- analogs to the sophisticated defensive grids envisioned by Star Trek's creators -- are ambient-temperature, ionized gases related to those found deep within the sunís core.

    Such plasmas are capable of shielding satellites and other spacecraft, making them invisible to radars, or both. Nor will they fry electronics or melt metal.

    Plasma: What is it?
    Plasma is the fourth state of matter, prevalent in the interstellar medium and in stars. Want to learn more?

    On Earth, cold plasmas should permit rapid, room-temperature sterilization of food, medical equipment and contaminated civilian and military gear. Low-temperature plasmas could one day also make possible an entire new generation of miniature lasers and ultra-low-energy fluorescent light tubes.

    While scientists have known of low-temperature plasmas since at least the end of the 19th century, only within the past several years have techniques emerged to make cold plasma generation practical.



    ďThis Star Wars stuff is coming .... A good cold plasma could really help out by reflecting or absorbing energy from a microwave war weapon.Ē


    Vaulting to the first ranks of cold-plasma research in the last three years has been soft-spoken, unassuming Tunisian native Mounir Laroussi, an electrical and computer engineer at Old Dominion University in Norfolk, Virginia. Research groups at Stanford, Princeton, Ohio State, Wisconsin and New York Polytechnic also are conducting their own plasma-research programs.

    Side view of a cold plasma inside a Pyrex glass container. Cold plasmas can cloak satellites and spacecraft from radar view and shield them against attack from certain kinds of energy weapons.

    Laroussi has literally put plasma on the table: devising an apparatus that creates a mini-plasma inside a Plexiglas cube by passing an electric current through helium gas via specially calibrated electrodes.

    ~

    Laroussiís process, specified in pending patent applications, is scalable; cold-plasma containers of virtually any size are feasible. No vacuum pumps are required, since the plasma is generated at normal atmospheric pressure.

    "Mounir is on the forefront. Heís one of the pioneers," said Igor Alexeff, president of the Institute of Electrical and Electronics Engineers' Nuclear and Plasma Sciences Society and professor emeritus of electrical engineering at the University of Tennessee in Knoxville. "Heís pushing very hard to develop a variety of practical plasmas. His work is pretty impressive."

    Invulnerable and invisible

    The U.S. Air Force allocates some $10 million a year for research geared toward satellite protection. Of that amount, $2 million is dedicated to low-temperature plasma studies.

    Robert Barker, program manager for plasma physics in the Air Forceís Office of Scientific Research in Arlington, Virginia is so taken with Laroussiís approach that he thus far has funneled $250,000 into Laroussiís research since his arrival at Old Dominion from the University of Tennessee a little over a year ago. The Air Force has supported Laroussiís work since 1996.

    Barker is drawn not just by Laroussiís plasma-creating prowess, but his ability to make low-temperature plasma inexpensively, in bulk and without the need for hulking equipment.

    "Whatís intriguing about Mounirís work is the large volumes of plasma heís been able to generate," Barker said. "Heís making very good progress in keeping costs and weight low. His approach gives the best power figures for practical, large-volume generation of cold plasma we have to date."

    Power-hungry plasmas

    Poke a finger inside Laroussiís tabletop plasma-generating apparatus and all youíll get from the bluish, pilot-light-like ionized gas is a slight tingle. But the harmless sensation is misleading, since it doesnít give a complete picture of plasmaís power. Depending on how a plasma is "tuned," or how it is made more dense by increasing its frequency, it could ward off microwave bursts and discharges from ground-based, energized sources of potential damage and disruption.

    Swirling in and around one another, a plasmaís charged particles interact constantly, giving rise to localized attractions or repulsions. External energy splashing against the plasma --- say, from a potentially disabling, concentrated burst of microwaves, or perhaps even from certain varieties of particle-beam weapons fired from military bases on Earth -- could be caught up within the plasmaís complex electromagnetic fields to be dissipated completely or deflected into space.

    Hotter plasmas, while dense, donít appear immediately practical as a defensive shield because of destructive temperatures and high power requirements. In theory, cold plasmas can be made denser, but like their hotter kin will demand more power. Energy availability and weight --- the larger the required wattage, the heavier the equipment --- would remain thorny issues.

    "In theory, a plasma could deflect a particle beam or laser attack," Laroussi says. "It depends on what youíre shooting at it and how high you can tune the plasma frequency. That doesnít mean itís easy or practically achievable, particularly with a cold plasma. Itís a tough requirement to meet at present."

    Cloaking mirrors

    A nearer-term application is cloaking. With the proper adjustments, a plasma can be made into a kind of energy mirror, reflecting back or away incoming electromagnetic waves, such as those emitted from ground-based radars. In essence, any spacecraft outfitted with this kind of plasma field would be completely cloaked from the probing attentions of radar operators.

    "The idea is to deflect or absorb the energy completely," Laroussi said. "If you absorb the energy --- completely dissipating it within the plasma --- the radar doesnít see anything. Nothing reflects back."

    Light but potent

    Lofting payloads into space must currently observe one of the Space Ageís key commandants: Make nothing so heavy that it must cost much to launch.

    Any on-board plasma-generation equipment would therefore have to be small and lightweight. Laroussiís gear seems to fit the bill -- compact enough to save on weight, yet powerful enough to produce the necessary plasma volume.

    But donít expect completely impervious shields anytime soon. Any number of technical issues remains to be solved, not the least of which is exactly how to make cold plasmas dense enough to withstand attack. The ultimate --- protection against projectiles or lasers --- is likely decades away, at best.

    "Ablative shields made of solid material might work," said the Air Forceís Barker. "A portion of the solid would be converted to plasma [when hit]. But In a strict sense, I donít consider that plasma shielding."

    The Star Wars stuff

    Less immediately space-like, but no less practical, are biological applications. Cold plasmas allow for rapid decontamination of clothing, equipment or personal gear. In disrupting the integrity of cell membranes, the plasmas appear to offer a rapid, simple and inexpensive means of destroying even the hardiest bacterial spores. At present, sterilization time can run hours; use of a cold plasma could sanitize in mere minutes.

    End-on view of a cold plasma inside a glass cylinder. This particular variety can be used to break down toxic gases into harmless constituents. The apparent "steering wheel" is an optical by-product of the cylinder's shape and the way the plasma is generated.

    Should this application pan out, it could offer to hospitals and armies alike a safe and reliable way to counteract potential health hazards, either those posed by disease or in combat. Likewise, exobiologists might rest easy knowing that cold plasmas could remove the potential threat of contamination from collected interplanetary samples returned to Earthís surface.

    Still, itís hard to vanquish all the Sci-Fi combat scenarios. Plasmas may be one of the best defensive options as offensive capabilities continue a rapid and relentless advance.

    "This Star Wars stuff is coming," said Igor Alexeff. "Laser and high-power microwave weapons are on the way; theyíre almost here. Lasers are fierce weapons. To protect against them, youíd need a very dense plasma, almost a solid. But a good cold plasma could really help out by reflecting or absorbing energy from a microwave-powered war weapon."
    Libertatem Prius!


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    Default Re: Force Fields and 'Plasma' Shields Get Closer to Reality

    Cold Plasma Ignites Hot Applications

    By James Schultz

    If somehow it were possible to scratch the surface of the sun without incinerating, Old Dominion research assistant professor of electrical and computer engineering Mounir Laroussi might give it a go. For now, Laroussi has settled for a quick and literal touch of a bluish, pilot-light-like ionized gas in his laboratory — otherwise known as plasma, and often described as a fourth state of matter.

    Fortunately, when Laroussi pokes a finger inside, no skin chars; no damage is done. He’s also tested paper, plastics, glass, rubber, even a small hair brush, with no ill effect. Unlike solar plasmas, which can reach many millions of degrees Fahrenheit, this discharge remains at room temperature. Still, Laroussi’s cool tabletop plasma has much in common with the sun’s fusion reactions that produce the heat and light that bathe Earth and make it habitable.

    “If you put a finger inside a cold-plasma plume it gives you a little tinge. It’s nothing much,” Laroussi asserts. “But you wouldn’t want to leave it there unless you wanted to sterilize your skin.”

    Sterilization of food, medical equipment, and contaminated civilian and military gear is just one potential major application of so-called “cold” plasmas. These ambient-air-temperature ionized gases could also be used as a Star Trek-like protective shield around sensitive electronics-bearing devices, such as satellites; as cloaking technology for military aircraft, as a means of absorbing radar waves in order to remain hidden on enemy screens; and as components of a new generation of miniature lasers and in advanced, low-energy-consumption flourescent light tubes.

    “It’s easy to make plasmas at low pressures, like the near-vacuum of space. It’s much harder to initiate and maintain them at low temperature and at atmospheric pressure,” Laroussi says. “What my co-workers and I have managed to do is to figure out a cost-effective way to make plasma, keep it cold and generate it in volume. We probably produce more total cold plasma than anyone else in the world, and at a relatively low level of input power.

    “The beauty of this is that it’s relatively inexpensive. The device we’re using costs less than $1,000. Compare that to a fusion reactor, which costs millions, or other, smaller devices that start at tens or hundreds of thousands of dollars. Ours is very practical.”

    Cooking The Cosmic Soup

    Interest in plasma physics initially developed because of radio communications and the effect of Earth’s ionosphere on radio-wave transmission. Because the ionosphere is essentially a plasma, ranging from approximately 50 to 600 miles above the planet’s surface, radio waves are partly absorbed by ionized air and in part refracted, or bent downward. The bending effect makes possible reception at distances much greater than for signals sent in a straight line, ones that could not follow the curvature of the globe.

    Plasmas, a kind of cosmic soup comprised of molecules, atoms, electrons and ions, comprise 99 percent of the known universe. The three other known states of matter — solids, liquids and gases — make up a mere 1 percent. Plasmas are most commonly found in interstellar space, where residual hydrogen is ionized by radiation, and in stars whose energy-generating efficiencies earthbound scientists have long desired to emulate.

    In stars, for hydrogen nuclei to fuse into heavier nuclei, they must be fast enough to overcome a mutual electric repulsion when the hydrogen ionizes into a plasma. Very hot plasmas overcome these limitations when their constituent particles collide with one another, acquiring sufficient energy to fuse, releasing enormous energy. Such reactions are at the literal heart of the sun’s core and, for the next four or so billion years, a ready and abundant source of solar heat.

    If the same kind of forces that have kept the sun’s nuclear furnace burning thus far could somehow be efficiently replicated terrestrially, power would be abundant and inexpensive, even in the world’s remotest regions. Unlike nuclear fission, fusion poses little significant environmental threat. However, despite researchers’ best efforts, technical problems have so far derailed efforts to produce practical fusion-based power.

    An Explosion of Interest

    Laroussi is not seeking to build a miniature fusion generator in his laboratory at the Applied Research Center in Newport News. Although his cold-plasma approach involves the excitation of helium gas inside a plexiglass cube (inside a star, hydrogen is converted into helium), the key is the way in which electric current flows in and through the gas via specially calibrated electrodes. The formula, specified in pending patent applications, is scalable; cold-plasma containers of virtually any size are feasible.

    That’s especially good news when it comes to rapid decontamination of clothing, equipment or personal gear. In disrupting the integrity of cell membranes, cold plasmas appear to offer a rapid, simple and inexpensive means of destroying even the hardiest bacterial spores. Time required for sterilization would nosedive, from many hours to mere minutes. Should this application pan out, it could offer to hospitals and armies alike a safe and reliable way to counteract potential health hazards, either those posed by disease or in combat.

    To elucidate the agents and molecular sites of plasma-induced cell damage, Laroussi has teamed with Fred Dobbs, an associate professor in Old Dominion’s Department of Ocean, Earth and Atmospheric Sciences. Laroussi remains cautious in assessing cold plasma’s decontamination potential. “We have our work cut out for us,” he says. “I’ll be more gratified when we really understand the biochemical and biophysical details of the phenomenon that are occurring.”

    Other defense-related, cold-plasma applications, such as electronics shielding and radar-absorbing cloaking, have so intrigued the Air Force Office of Scientific Research that it has underwritten Laroussi’s work to the tune of $300,000 over the last five years, with a separate, additional grant of $167,000 awarded just this year. Given Laroussi’s technological achievement and clear progress, further funding from private and public sources may be forthcoming. More patents are pending, as are additional uses.

    In recognition of his achievements in plasma science, this spring Laroussi was slated to receive the Millennium Graduate of the Last Decade (GOLD) Award from the Institute of Electrical and Electronics Engineers, one of the largest professional societies in the world. “There is interest everywhere now in plasma science,” he says. “The military is interested. The scientific community is interested. The general public is interested.

    “This is a field that will only grow. We at Old Dominion will be on the forefront. We’ll be one of the leaders.”
    Libertatem Prius!


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