Scientists achieve breakthrough in fuel-cell technology

Embargoed for Release at 11 a.m. PST, Wednesday, April 18, 2001

PASADENA, Calif.—Gasoline averaging $3 per gallon? Oil drilling in an Alaskan wildlife reserve? A need to relax air quality standards? It seems the long-term future of fossil fuels is bleak. One promising solution scientists have been studying is fuel cells, but they've had limitations too. Now, in the April 19 issue of the science journal Nature, the California Institute of Technology's Sossina M. Haile reports on a new type of fuel cell that may resolve these problems.

Unlike the engines in our cars, where a fuel is burned and expanding gases do the work, a fuel cell converts chemical energy directly into electrical energy. Fuel cells are pollution free, and silent. The most common type now being developed for portable power—the type used in today's fuel-cell-powered prototype cars—is a polymer electrolyte fuel cell. An electrolyte is a chemical that can conduct electricity, and is at the heart of the fuel cell. Polymer electrolytes must be humidified in order for the fuel cell to function, can only operate over a limited temperature range, and are permeable. As a consequence, polymer electrolyte fuel cell systems require many auxiliary components and are less efficient than other types of fuel cells.

Haile, an assistant professor of materials science, has taken a completely different tack, developing an alternative type of fuel cell that is not a hydrated polymer, but is instead based on a so-called "solid acid." Solid acids are chemical compounds, such as KHSO4 (potassium hydrogen sulfate). Their properties are intermediate between those of a normal acid, such as H2SO4 (sulfuric acid), and a normal salt, such as K2SO4 (potassium sulfate). Solid acids can conduct electricity at similar values to polymers, they don't need to be hydrated, and they can function at high temperatures, up to 250 degrees Centigrade. Solid acids are also typically inexpensive compounds that are easy to manufacture.

But until now such solid acids have not been examined as fuel-cell electrolytes because they dissolve in water and can lose their shape at even slightly elevated temperatures. To solve these problems, Haile and her graduate students Dane Boysen, Calum Chisholm and Ryan Merle, operated the fuel cell at a temperature above the boiling point of water, and used a solid acid, CsHSO4, that is not very prone to shape changes.

The next challenge, says Haile, is to reduce the electrolyte thickness, improve the catalyst performance, and, most importantly, prevent the reactions that can occur upon prolonged exposure to hydrogen. Still, she says, solid acid fuel cells are a promising development.

"The system simplifications that come about (in comparison to polymer electrolyte fuel cells) by operating under essentially dry and mildly heated conditions are tremendous. While there is a great deal of development work that needs to be done before solid acid based fuel cells can be commercially viable, the potential payoff is enormous."

The Department of Energy, as part of its promotion of energy-efficient science research, recently awarded Haile an estimated $400,000 to continue her research in fuel cells. She also recently received the J.B. Wagner Award of the Electrochemical Society (High Temperature Materials Division). She is the recipient of the 2001 Coble Award from the American Ceramics Society, and was awarded the 1997 TMS Robert Lansing Hardy Award. Haile has received the National Science Foundation's National Young Investigator Award (1994–99), Humboldt Fellowship (1992–93), Fulbright Fellowship (1991–92), and AT&T Cooperative Research Fellowship (1986–92).


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Impact of Caltech's Computer Science OptionCelebrated with 25th Anniversary Symposium

PASADENA, Calif.- Computer technology pioneers and today's leading innovators in the field will gather at Caltech on April 9 and 10 for a symposium in honor of the 25th anniversary of the California Institute of Technology computer science option. The event is free and open to the public. Presentations by Caltech alumni, former and current faculty, and distinguished colleagues will take place in Beckman Institute auditorium and in the Jorgensen Laboratory of Information Science.

The computer science option at Caltech has had an indelible impact on the computing world and continues with a strong research program in the fundamentals of computing, including investigations into such future possibilities as quantum computing and DNA computing. Scores of major developments in computer science have had their start in the labs and in the minds of faculty and students on the Caltech campus. The computer science option at Caltech has played a major role in the development of semiconductor (VLSI) chip design, internet-related technologies, massively parallel supercomputers, neural networks, and computer graphics, such as advanced animation techniques used widely in the film industry.

The symposium will recognize those who blazed new trails in computing when the option started in 1976, those who forever changed the way computing has been incorporated into our culture in the 1980s and 1990s, as well as those who are developing futuristic technologies today.

On April 9, the program begins with a discussion of chips and VLSI, and the speakers include the father of VLSI — and continuing technology innovator — Carver Mead, the Gordon and Betty Moore Professor of Engineering and Applied Science, Emeritus, at Caltech and the founder of Foveon, a digital camera manufacturing company. He will be followed by Ivan Sutherland, a vice president and fellow at Sun Microsystems and one of the founders of the Caltech computer science option.

Additional topics to be addressed during the symposium are graphics, architecture, distributed systems, and learning systems. The graphics portion of the event will include Pixar Animation Studios president and recent Oscar recipient Ed Catmull. Also speaking is Jim Kajiya, assistant director, Microsoft Research, who was honored with an Academy of Motion Picture Arts and Sciences Technical Achievement Award in 1996. Current Caltech faculty member Erik Winfree, recipient of a MacArthur Foundation "genius" fellowship last year, will speak about future technologies under the topic "Beyond Silicon." A full list of speakers may be found on the symposium website at

The symposium also includes a panel discussion on entrepreneurship and computer science, moderated by the chairman of the Caltech board of trustees, Ben Rosen, chairman emeritus of Compaq. Panelists include William Davidow of Mohr, Davidow Ventures; Lounette Dyer, Silk Road Technology; Bill Gross, idealab!; Carver Mead, Foveon; and Phil Neches, founder, Teradata. This panel discussion will take place at 3 p.m. April 9.

For questions regarding the symposuim, contact Marionne Epalle, (626) 395-8093, or e-mail her at

The symposium schedule follows.

Monday, April 9, Beckman Institute auditorium 7:30 a.m. - Continental breakfast 8 a.m. - Greetings and introduction, Professor Richard Murray, chair, Division of Engineering and Applied Science

Chips/VLSI 8:30 a.m. - Carver Mead, Caltech, Foveon 9 a.m. - Ivan Sutherland, Sun Microsystems 9:30 a.m. - William Dally, Stanford University 10 a.m. - Break 10:30 a.m. - Alain Martin, Caltech

Graphics 11 a.m. - Ed Catmull, Pixar 11:30 a.m. - Jim Kajiya, Microsoft Noon - Lunch in Beckman Institute courtyard 1:30 P.M. - Peter Schröder, Caltech

Learning Systems 2 p.m. - Yaser Abu-Mostafa, Caltech 2:30 p.m. - Break

3 –5 p.m. - Panel on Entrepreneurship and Computer Science. Moderator, Ben Rosen, Chairman Emeritus of Compaq and current chair of the Caltech board of trustees. Panelists: William Davidow of Mohr, Davidow Ventures; Lounette Dyer, chair of Silk Route Technology; Carver Mead, chair of Foveon; Phil Neches, consultant and founder of Teradata; and Bill Gross, chair of idealab!.

Tuesday, April 10, Beckman Institute auditorium 7:45 a.m. - Continental breakfast

Architecture and Distributed Systems 8:30 a.m. - Chuck Seitz, Myricom 9 a.m. - Mani Chandy, Caltech 9:30 a.m. - Rajiv Gupta, Hewlett-Packard 10 a.m. - Break 10:30 a.m. - Thomas Sterling, JPL/CACR

Beyond Silicon 11 a.m. - Erik Winfree, Caltech 11:30 - André Dehon, Caltech Noon - Leonard Schulman, Caltech 12:30 p.m. - Lunch, poster session, open house at Jorgensen Laboratory of Information Science ### Contact: Jill Perry, media relations director (626) 395-3226

Visit the Caltech media relations website:


Caltech's annual machine competition to be held Nov. 30

PASADENA—Caltech engineering students will put their freshly built robotic rovers through their paces when they compete for top honors at the 16th annual ME72 Engineering Design Contest at 2 p.m. Thursday, November 30, in Beckman Auditorium.

The celebrated contest lets undergraduate students match wits and design acumen to see whose machine is best at performing a contrived task. The media are invited to attend and cover the event, which should last about 90 minutes.

At the beginning of the 2000 fall term, the 18 students registering for Mechanical Engineering 72 were given a design task, a "bag of junk," and a limited number of weeks to build a machine they judged capable of performing the assigned feat during a public contest. The students, paired up in nine teams, will by November 30 have finished designing, prototyping, fabricating, assembling, testing, debugging, and tuning their machines, preparing to see whose device is tops in the final contest.

In this year's contest the machines will compete in a large box rather than on a horizontal game table as in previous years, said Erik Antonsson, a professor of mechanical engineering at Caltech, longtime instructor of ME72, and originator of the design contest.

"The task this year is to attach small cubes and cylinders to the magnetic back wall of a 16-foot by 5-foot by 4-foot Plexiglass box," Antonsson said. "Also, we've gone wireless this year, so students will be liberated from their electrical umbilical cords." The annual contest has become a highlight of the Caltech academic year for students and faculty alike. Though the contest itself is entertaining for onlookers, Antonsson said the real motivation is to teach students how to design and build engineered devices that can hold up—and perhaps even perform superlatively—in the real world.

"Engineering is primarily the process of creating new things to solve problems," Antonsson said. "This course and contest is one attempt to provide students with a real-world opportunity to learn about the design of new things and the solution of open-ended, ill-defined problems."

The event is sponsored by Schlumberger, Honeywell/AlliedSignal, Northrop Grumman Corp., Ford Motor Company, General Motors, Biosense Webster, Boeing Satellite Communications, idealab!, the San Diego Foundation, Dr. David and Mrs. Barbara Groce, GE Energy and Environmental Research Corporation, Hewlett-Packard, Novak Electronics, TORO, and Valeo, Inc.

MEDIA ACCESS: The contest is open to the news media and Caltech community. Media will have special seating in the front two rows on the right side of the auditorium, and in the center of the front row. To ensure that the hundreds of students, faculty, and staff have a clear view of the contest, we ask that the press not stand on or in front of the stage.

Jill Perry

NSF awards $9.6 million for materials research center at Caltech

The National Science Foundation today awarded $9.6 million in start-up funding for the Center for the Science and Engineering of Materials (CSEM) at the California Institute of Technology. The new center pioneers a number of exotic and futuristic materials and applications such as "liquid" metals, responsive gels, and tiny medical sensors.

The CSEM will be one of four new National Science Foundation-funded centers in the Materials Research Science and Engineering Center (MRSEC) program. Each of the four new centers will be in keeping with the MRSEC's mission "to undertake materials research of scope and complexity that would not be feasible under traditional funding of individual research projects."

The Caltech center will focus on four areas of research that are already emerging as unique, high-impact activities on campus, says Julia Kornfield, associate professor of chemical engineering at Caltech and director of the center.

"We've chosen four major areas of scientific interest that will help solve critical societal needs of the twenty-first century," says Kornfield. "We'll have strong ties to industrial and other laboratories, and we'll provide a substantial educational program for public schools and other institutions."

The four major areas will be biological synthesis and assembly of macromolecular materials, bulk metallic glasses and composites, mesophotonic materials, and ferroelectric thin films.

The biosynthesis initiative of the center will be led by David Tirrell, chair of Caltech's Division of Chemistry and Chemical Engineering. Research efforts will include the use of artificial proteins to make polymers with exquisite control of properties, and responsive polymers and gels for biomedical and industrial applications, including materials for entrapment of cells in tissue engineering or biosensors.

"This new technology takes advantage of traditional materials properties and biological functions such as signaling and information transfer," Tirrell says.

The team investigating glassy metallic alloys will be led by Bill Johnson, a professor of materials science at Caltech. This group will pursue basic science and new engineering strategies that will lead to custom-designed materials with desirable characteristics such as ultrahigh strength, exceptional elasticity, and ease of fabrication into complex parts.

The effort toward mesophotonics will be led by Harry Atwater of the Caltech applied physics faculty. Mesophotonic devices are optical components and devices at or below the wavelength of light. Future applications include engineered optical probes for biology and medicine, and photonic devices that could replace certain electrical devices in telecommunications and computing.

Kaushik Bhattacharya, professor of applied mechanics and mechanical engineering, will lead research to enable microactuators based on high strain ferroelectrics. The team's integrated simulation and experimental approach promises to reveal the microscopic basis of large strain behavior in this class of materials.

The new center will be interdisciplinary, not only because researchers >from varied backgrounds will work in each area, but also because the areas themselves overlap, Kornfield says. The self-assembly of nanostructured materials is applicable to the mesophotonics area as well as to the biological synthesis area, she says.

"Caltech provides an excellent setting for this ambitious center due to the extensive investments that the Institute has made over the past decade, building the campus-wide activities and facilities in materials research. And strong institutional commitments to technology transfer and educational outreach will ensure that the impact of this center is felt far beyond the Caltech campus," says Kornfield.

Outreach programs will enrich educational opportunities in science and engineering for underrepresented minority students at the undergraduate, middle school and high school levels. The center will establish a materials pPartnership between Caltech and nearby California State University, Los Angeles, that will involve CSULA students and faculty in CSEM research, and foster materials research and curriculum on the CSULA campus.

The center will also establish an extensive network of research collaborations in the private sector with companies such as Lucent, Exxon, Dow, Procter and Gamble, 3M, and General Motors, and with government laboratories such as JPL and Brookhaven.

Robert Tindol
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NSF funds new Institute for Quantum Information at Caltech

The National Science Foundation has awarded a five-year, $5 million grant to the California Institute of Technology to create an institute devoted to quantum information science—a new field that could ultimately lead to devices such as quantum computers.

The announcement was part of a $90 million information technology research initiative the NSF announced today in Washington. The awards are aimed at seeding fundamental research in innovative applications of information technology.

Caltech's new Institute for Quantum Information will draw on several fields, including quantum physics, theoretical computer science, mathematics, and control and dynamical systems engineering, says founding director John Preskill, a professor of theoretical physics at Caltech.

"The goal of the institute will be to understand ways in which the principles of quantum physics can be exploited to enhance the performance of tasks involving the transmission, processing, and acquisition of information," says Preskill, who has worked on quantum computation algorithms for the last five years.

"The most potentially exciting aspect of the field is the promise of a quantum computer," he says. "If you could process quantum states instead of classical information, there are problems you could solve that could never be solved with classical technology."

Quantum computers would be more efficient than conventional computers because they would greatly reduce the number of steps the computer would have to jump through to solve many problems. For example, the encryption used to protect credit cards relies on the fact that it would take huge amounts of time for a conventional computer to break down a large number into its factors (the numbers one multiplies together that will equal this number).

It now takes the best computers several months to find the factors of a 130-digit number, and it would take 10 billion years to factor a 400-digit number—nearly the entire age of the universe. But a quantum computer with the same clock speed could factor the 400-digit number in about a minute, according to the figures Preskill has worked out.

At the same time, quantum information would provide a new means to thoroughly protect information from any intruder, Preskill says.

"By using quantum information, it's possible to make unbreakable codes, and this security is founded on fundamental physical laws," he says.

Also, the work of the new institute will advance research in the further miniaturization of classical electronic components. Quantum effects are becoming increasingly important for microelectronics as devices continue to shrink toward atomic dimensions.

In addition to Preskill, the Institute for Quantum Information will be led by two co-principal investigators who, in consultation with other Caltech researchers, will guide and supervise scientific activities. The initial co-principal investigators will be Jeff Kimble, an experimental physicist who has done groundbreaking work in the transmission of quantum information, and John Doyle, a professor of electrical engineering who is interested in control issues of quantum systems.

Other investigators at the institute will include Michelle Effros, Hideo Mabuchi, Michael Roukes, Axel Scherer, and Leonard Schulman, all Caltech faculty members. The institute will develop a substantial visitors' program and will aim at hiring postdoctoral researchers and graduate students who wish to enter the field of quantum information systems.

Contact: Robert Tindol (626) 395-3631


Two Caltech faculty named MacArthur Fellows

PASADENA—The California Institute of Technology has two new faculty geniuses, and each has been awarded $500,000 from the John D. and Catherine T. MacArthur Foundation to prove it.

Erik Winfree, an assistant professor of computer science and computation and neural systems, and Hideo Mabuchi, an assistant professor of physics, both received word last week that they are among the 25 new MacArthur Fellows in the program often referred to as the "Genius Grants." The awards are presented each year to individuals chosen for their exceptional creativity, accomplishments, and potential—no strings attached.

Mabuchi, a specialist in quantum optics, says he was surprised by the phone call and is not yet sure exactly what he'll do with the money.

"I may try to incorporate creativity into the type of science education we normally do at Caltech," he said. "Physics usually builds technical skills, so I would like to see if something could be done to encourage creative skills."

Mabuchi's research primarily explores the details of how microscopic quantum systems interact with macroscopic measurement and control devices used in the lab. This is an important avenue of work for future electronic devices, because as those devices become increasingly smaller, designers will find it more necessary to take quantum effects into consideration.

"Microelectronic devices are coming down to the size where you have to understand the physics very carefully," he said.

Winfree said he felt a "sense of freedom" when he received word of the award. Winfree's research emphasis is the emerging field of biomolecular computing, and he has been especially interested in DNA computing.

"I might, if I am lucky, be able to augment our understanding and imagination of computation in the molecular world," he said of his goals as a scientist. "The understanding of algorithms will serve as a key to understanding the behavior of complex systems such as the biological cell. The question is how to make this transfer of concepts concrete and useful.

"Thus, if my brief moment in the limelight is good for anything, I would like to champion—as others have before me—the notion that computer science is not just about computers. It is the study of processes that generate organization, wherever you find them: algorithms are a fundamental part of nature."

Winfree and Mabuchi, along with the other 23 winners this year, were nominated by an anonymous panel and then selected by a 13-member committee, also serving anonymously. The Fellows are required neither to submit specific projects to the foundation, nor to report on how the money is used.

An important underpinning of the program is the foundation's confidence that the Fellows are best able to decide how to use the money in furthering their work.





Caltech Professor Honored with Guggenheim Medal

PASADENA—California Institute of Technology professor emeritus Frank E. Marble was selected to receive the Daniel Guggenheim Medal and Certificate, which was presented on May 12 at the American Institute of Aeronautics and Astronautics' Global Air and Space 2000 International Business Forum and Exhibition, in Arlington, Virginia.

The honor is for Marble's "major fundamental, theoretical and experimental contributions to the fields of internal aerodynamics, combustion, and propulsion especially with respect to gas turbines and rockets, and educating generations of leaders in industry and academia," stated the announcement.

Marble received his bachelor's and master's degrees from the Case Institute of Technology in 1940 and 1942, respectively, and his engineer's degree and PhD from Caltech in 1947 and 1948. He is Caltech's Richard L. and Dorothy M. Hayman Professor of Mechanical Engineering and Professor of Jet Propulsion, Emeritus, and has also held visiting positions at Cornell, Cambridge, MIT, the Chinese Academy of Science, and the Chatenay-Malabry in France.

Marble's awards include the AIAA Propellants and Combustion Award and the Wright Brothers Medal, and he is a member of the National Academy of Engineering and the National Academy of Sciences.

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Caltech scientists develop first microscopic system of pumps and valves made from soft materials

PASADENA—Researchers at the California Institute of Technology have developed a pump that is less than one-half the width of a human hair. The device is a breakthrough in the 3-D microfabrication of soft materials and could be applied to revolutionize and simplify many technologies, including drug discovery and delivery, according to Caltech applied physics professor Stephen R. Quake and his colleagues, who report their findings in the April 7 issue of Science.

Unlike the silicon-based micromachining techniques used for computer chips, this team has developed a technique called multilayer soft lithography, which is essentially an intricate casting of soft rubber. The work is an extension of soft lithography casting, originally developed by George Whitesides at Harvard University.

"Basically, it's plumbing on a very small scale," says Quake. "We are trying to show that it is useful to make microdevices out of soft rubber for certain applications, rather than the hard materials like glass or silicon used in traditional micromachining. In order to make a valve, one needs to figure out how to make it seal, which is usually done with a rubber washer. We made the entire valve out of the sealing material."

The pump is made possible because of the material's softness and pliability. Embedded in a small clear rubber chip the size of a postage stamp, the pump is actually a series of tiny, multilayer channels that each measure 50 by 30 by 10 microns. By contrast, a human hair is about 100 microns wide.

Operation of the pump is similar to the peristaltic motions that make human digestion possible. By applying pressure in one of the channels, another channel above it or below it in the 3-D matrix can be closed off, thereby allowing the channel to act either as a pump or as a valve.

While the research is basic and mainly aimed at demonstrating the feasibility of the technique, Quake says the pump could have a number of practical applications, including drug delivery, one day possibly enabling doctors to implant a biocompatible device about the size of a postage stamp into a patient's body to deliver drugs for chronic disorders such as allergies, pain, diabetes and cancer.

The device may allow the drug to be delivered in a time-released manner customized for each patient. In addition to delivering the drug, the device could also contain a microsized component that would enable regular monitoring of the patient's condition.

Quake's own lab intends to use the microfabricated valves and pumps in two devices: a DNA sizer, which is a replacement for the current technique known as gel electrophoresis; and a cell sorter, a machine that physically separates microscopic materials such as bacteria or viruses. Both devices originated from research in Quake's lab. Caltech has licensed this technology to Mycometrix Corporation of South San Francisco, which will apply it to develop a variety of commercial products.

In addition to Quake, the others involved in the research are Axel Scherer, a professor of electrical engineering, applied physics, and physics at Caltech; Marc Unger, a postdoctoral scholar in applied physics; Hou-Pu Chou, a graduate student in electrical engineering; and Todd Thorsen, a graduate student in biochemistry.

Robert Tindol

Caltech Professor Yaser Abu-Mostafa Awarded Kuwait State Award

PASADENA-The California Institute of Technology's Yaser Abu-Mostafa, professor of electrical engineering and computer science, received the Kuwait State Award in Applied Science on November 29.

The $50,000 award includes a gold medal, and recognizes original and fundamental research in a designated area of applied science. This year's area was information science and technology. Abu-Mostafa's work on neural networks, learning from hints, and computational finance was cited as the pioneering contribution that merited the award.

Abu-Mostafa is the youngest person to receive this award since its establishment in 1979. The awards ceremony was televised live in a number of countries. A reception by the Emir of Kuwait at the Royal Palace followed.

Abu-Mostafa received a BSc from Cairo University in 1979, an MSEE from the Georgia Institute of Technology in 1981, and a PhD from Caltech in 1983. At Caltech he won the Clauser Prize for the most original doctoral thesis. He has been teaching at Caltech since 1983, and was recognized in 1996 with the Richard P. Feynman Award for Excellence in Teaching.

Sue Pitts McHugh

New physics research shows how twisted plasmas can suddenly generate unstable magnetic waves

PASADENA-Plasma physicists have long wondered why the geometric shape, or topology, of magnetic fields immersed in plasma sometimes changes very suddenly, when according to the laws of magnetohydrodynamics the magnetic topology should change only very slowly or not at all.

For example, according to magnetohydrodynamics, the arched twisted shapes of the beautiful prominences protruding from the sun's surface should stay unchanged for years. Yet it is observed that after a quiescent period of days or weeks, a solar prominence can erupt in a matter of minutes, change its shape drastically, and produce a burst of high-energy particles.

The answer is likely in the details, and new research from California Institute of Technology applied physics professor Paul Bellan provides a possible explanation for why seemingly steady magnetized plasma configurations can suddenly become unstable and change their overall shape. The research appears in the December 6 issue of Physical Review Letters.

"The basic prediction of magnetohydrodynamics has been that magnetic fields embedded in plasma tend to be frozen or glued to the plasma because plasma is a very good electrical conductor," says Bellan. "Thus, if the magnetic field moves, the plasma moves in such a way that magnetic field lines cannot slide across the plasma.

"This means that the topology is not supposed to change unless the plasma is a less-than-perfect conductor. Yet, in reality, many situations are observed where the magnetic field suddenly becomes unglued, even though the plasma is essentially a perfect conductor."

For plasmas immersed in strong magnetic fields, electric currents tend to flow along the magnetic field lines, which act like wires guiding the current. The field-aligned current creates its own magnetic field, and, when added to the original magnetic field, results in a twisted or helical magnetic field.

If two such helical magnetic fields happen to be beside each other, like two barber poles lying side by side, there is a sudden change in magnetic field angle at the interface, just like the sudden change in stripe direction in going from one barber pole to its neighbor.

"People have worried for many years about what happens in such a situation," Bellan says. "The answer seems to be that the sharp change in magnetic field angle as one moves from one twisted configuration to its similarly twisted neighbor forces a large sheetlike electric current in the interface between the two configurations.

"This current sheet consists of electrons moving along the magnetic field. The more abrupt the jump in magnetic field angle, the thinner the current sheet and the faster the electrons move."

If the jump in magnetic field angle is big enough, the electrons stream at a speed equal to the propagation velocity of a well-known magnetic plasma wave called the Alfven wave. When the electrons move in sync with the wave, they resonantly interact with the wave and cause it to grow unstably, carrying energy away from the current sheet and so altering the current sheet.

"This is interesting because it can rapidly change the magnetic field topology," he says. "So if you push together these two innocent-looking twisted structures, you create an unstable gain mechanism that suddenly generates magnetic waves and so causes a quick, violent change of the magnetic field."

In certain situations these waves could also accelerate ions to high energy, a behavior often observed to be associated with sudden changes in magnetic field geometry, but not well understood.

Bellan's model could provide improved understanding of such diverse phenomena as solar prominence eruptions; the aurora borealis and aurora australis; and plasma behavior in spheromaks, laboratory devices in which magnetic vortices suddenly break off like smoke rings from specially designed magnetized plasma sources.

In short, the new research is a microscopic theory that explains certain puzzling plasma phenomena observed at macroscopic levels.

"My theory is a stab at explaining this," Bellan says. "It's not the end answer, but certainly a new twist."

Robert Tindol


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