News & Events


Observations Reshape Basic Plasma Wave Physics


Paul M. Bellan, Professor of Applied Physics , and colleagues have discovered a new way to determine the wavelength of energy flowing through plasma in space—a method that was recently applied during a NASA mission that yielded the first solid evidence of how energy sloshes back and forth in a magnetic wave that moves through the plasma surrounding the earth. [Caltech story]

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Using Applied Physics to Explain How Accretion Disks Drive Astrophysical Jets


Paul M. Bellan, Professor of Applied Physics, has developed a new model explaining why astrophysical jets always originate from stars having accretion disks, the progenitors of planets. The relationship between jets and accretion disks has eluded scientists for many years and what happens to the angular momentum of accreting particles has also long been a mystery. Professor Bellan’s model explains how the disks power the jets as well as how angular momentum is removed from accreting material in the disks. The model involves peculiar inward spiraling trajectories of clumps of charged and neutral particles, and shows that the disk and jets together form an electric circuit where the disk is the battery and the jet is the load. [Read the Paper]

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Senior Spotlight


Electrical Engineering Senior Raymond Jimenez was first introduced to Caltech as a high school student when he worked in the laboratory of Paul Bellan. As a Caltech undergraduate his favorite class was APh/EE 9, Solid-State Electronics for Integrated Circuits—a course then taught by Oskar Painter. He also worked on a Summer Undergraduate Research Fellowship (SURF) project with Axel Scherer, who describes Jimenez as "one of the most capable undergraduates whom I have had the pleasure of working with over my past 20 years at Caltech," adding that he has "extraordinary" abilities. "Raymond brought tremendous enthusiasm, talent, and insight to our neural probe project," Scherer says. "It was fun working with him on our research projects, and I think of him more as a scientific collaborator than as a student." Raymond and his peers will be honored at Caltech's 119th Commencement on June 14 at 10 a.m. [Caltech Spotlight]

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Solar Loops and Space Weather


Paul M. Bellan, Professor of Applied Physics, and colleagues have reproduced plasma loops in the laboratory to help understand solar physics. "We're studying how these solar loops work, which contributes to the knowledge of space weather," says Professor Bellan, who compares the research to studying hurricanes. For example, you can't predict a hurricane unless you know more about the events that precede it, like high-pressure and low-pressure fronts. The same is true for solar flares. "It takes some time for the plasma to get to Earth from the sun, so it's possible that with more research, we could have up to a two-day warning period for massive solar flares." [Caltech Release] [E&S Article]

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Plasmas Torn Apart


Using high-speed cameras to look at jets of plasma in the lab, Paul M. Bellan, Professor of Applied Physics, and colleagues have made a discovery that may be important in understanding phenomena like solar flares and in developing nuclear fusion as a future energy source. "Trying to understand nature by using engineering techniques is indeed a hallmark of the Division of Engineering and Applied Science at Caltech," says Ares Rosakis, Chair of the Engineering and Applied Science Division. [Caltech release] [Plasma movie]

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Paul Bellan Gives Explanation for a Strange Property of Night-shining Clouds


An explanation for a strange property of night-shining clouds has been proposed by Paul Bellan, Professor of Applied Physics. Noctilucent clouds - thin, wispy electric blue clouds clouds hovering at 85 km altitude - are highly reflective to radar. Ice grains in noctilucent clouds are coated with a thin film of metal, made of sodium and iron. The metal film causes radar waves to reflect off ripples in the cloud in a manner analogous to how x-rays reflect from a crystal lattice. [Caltech Press Release]

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Department of Applied Physics and Materials Science