James F. Drake | |
---|---|
Born | |
Nationality | American |
Education | University of California, Los Angeles (B.S., M.S., Ph.D.) |
Known for | Fast magnetic reconnection |
Awards | |
Scientific career | |
Fields | Plasma physics |
Institutions | University of Maryland |
Website | terpconnect |
James F. Drake (born June 26, 1947) is an American theoretical physicist who specializes in plasma physics. [1] He is known for his studies on plasma instabilities [2] [3] and magnetic reconnection [4] [5] for which he was awarded the 2010 James Clerk Maxwell Prize for Plasma Physics by the American Physical Society. [6]
Drake studied at the University of California, Los Angeles (UCLA), where he received his bachelor's degree in 1969 and received his doctorate in 1975. In 1977, he went to the University of Maryland, where he has been a professor since 1987.
He dealt with laser-plasma interaction and plasma turbulence. [7] He is known for explaining the mechanisms of the rapid reconnection of magnetic field lines and the resulting particle accelerations in astrophysical plasmas (for example on the sun). [8] In computer simulations with Amitava Bhattacharjee and Michael Hesse (NASA), he was able to demonstrate the explosive nature of the dynamics of the magnetic fields, for example in solar flares. [9]
In 1986, Drake was elected a fellow of the American Physical Society. [10] He was subsequently awarded the 2010 James Clerk Maxwell Prize for Plasma Physics for "pioneering investigations of plasma instabilities in magnetically-confined, astrophysical and laser-driven plasmas; in particular, explication of the fundamental mechanism of fast reconnection of magnetic fields in plasmas; and leadership in promoting plasma science". [6]
He also received a Senior US Research Scientist Award from the Alexander von Humboldt Foundation.[ citation needed ]
A coronal mass ejection (CME) is a significant ejection of magnetic field and accompanying plasma mass from the Sun's corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established.
Magnetic reconnection is a physical process occurring in electrically conducting plasmas, in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle acceleration. Magnetic reconnection involves plasma flows at a substantial fraction of the Alfvén wave speed, which is the fundamental speed for mechanical information flow in a magnetized plasma.
Adolfo Figueroa-Viñas is the first Puerto Rican astrophysicist at the National Aeronautics and Space Administration (NASA) and is an expert in solar and space plasma physics at the Heliophysics Science Division. As a staff scientist his research interests include studying plasma kinetic physics and magnetohydrodynamics of the solar wind, heliosphere, shock waves, MHD and kinetic simulation of plasma instabilities, and turbulent processes associated with space, solar and astrophysical plasmas.
Liu Chen is an American theoretical physicist who has made original contributions to many aspects of plasma physics. He is known for the discoveries of kinetic Alfven waves, toroidal Alfven eigenmodes, and energetic particle modes; the theories of geomagnetic pulsations, Alfven wave heating, and fishbone oscillations, and the first formulation of nonlinear gyrokinetic equations. Chen retired from University of California, Irvine (UCI) in 2012, assuming the title professor emeritus of physics and astronomy.
A nanoflare is a very small episodic heating event which happens in the corona, the external atmosphere of the Sun.
John Bryan Taylor is a British physicist known for his contributions to plasma physics and their application in the field of fusion energy. Notable among these is the development of the "Taylor state", describing a minimum-energy configuration that conserves magnetic helicity. Another development was his work on the ballooning transformation, which describes the motion of plasma in toroidal (donut) configurations, which are used in the fusion field. Taylor has also made contributions to the theory of the Earth's Dynamo, including the Taylor constraint.
The ballooning instability is a type of internal pressure-driven plasma instability usually seen in tokamak fusion power reactors or in space plasmas. It is important in fusion research as it determines a set of criteria for the maximum achievable plasma beta. The name refers to the shape and action of the instability, which acts like the elongations formed in a long balloon when it is squeezed. In literature, the structure of these elongations are commonly referred to as 'fingers'.
The Spitzer resistivity is an expression describing the electrical resistance in a plasma, which was first formulated by Lyman Spitzer in 1950. The Spitzer resistivity of a plasma decreases in proportion to the electron temperature as .
Supra-arcade downflows (SADs) are sunward-traveling plasma voids that are sometimes observed in the Sun's outer atmosphere, or corona, during solar flares. In solar physics, arcade refers to a bundle of coronal loops, and the prefix supra indicates that the downflows appear above flare arcades. They were first described in 1999 using the Soft X-ray Telescope (SXT) on board the Yohkoh satellite. SADs are byproducts of the magnetic reconnection process that drives solar flares, but their precise cause remains unknown.
A sawtooth is a relaxation that is commonly observed in the core of tokamak plasmas, first reported in 1974. The relaxations occur quasi-periodically and cause a sudden drop in the temperature and density in the center of the plasma. A soft-xray pinhole camera pointed toward the plasma core during sawtooth activity will produce a sawtooth-like signal. Sawteeth effectively limit the amplitude of the central current density. The Kadomtsev model of sawteeth is a classic example of magnetic reconnection. Other repeated relaxation oscillations occurring in tokamaks include the edge localized mode (ELM) which effectively limits the pressure gradient at the plasma edge and the fishbone instability which effectively limits the density and pressure of fast particles.
Dmitri Dmitriyevich Ryutov is a Russian theoretical plasma physicist.
Ravindra Nath Sudan was an Indian-American electrical engineer and physicist who specialized in plasma physics. He was known for independently discovering the whistler instability in 1963, an instability which causes audible low-frequency radio waves to be emitted in the magnetosphere in the form of whistler waves. He also pioneered the study of the generation and propagation of intense ion beams, and contributed to theories of plasma instabilities and plasma turbulence.
Masaaki Yamada is a Japanese plasma physicist known for his studies on magnetic reconnection.
William Henry Matthaeus is an American astrophysicist and plasma physicist. He is known for his research on turbulence in magnetohydrodynamics (MHD) and astrophysical plasmas, for which he was awarded the 2019 James Clerk Maxwell Prize for Plasma Physics.
Toshiki Tajima is a Japanese theoretical plasma physicist known for pioneering the laser wakefield acceleration technique with John M. Dawson in 1979. The technique is used to accelerate particles in a plasma and was experimentally realized in 1994, for which Tajima received several awards such as the Nishina Memorial Prize (2006), the Enrico Fermi Prize (2015), the Robert R. Wilson Prize (2019), the Hannes Alfvén Prize (2019) and the Charles Hard Townes Award (2020).
Solar radio emission refers to radio waves that are naturally produced by the Sun, primarily from the lower and upper layers of the atmosphere called the chromosphere and corona, respectively. The Sun produces radio emissions through four known mechanisms, each of which operates primarily by converting the energy of moving electrons into electromagnetic radiation. The four emission mechanisms are thermal bremsstrahlung (braking) emission, gyromagnetic emission, plasma emission, and electron-cyclotron maser emission. The first two are incoherent mechanisms, which means that they are the summation of radiation generated independently by many individual particles. These mechanisms are primarily responsible for the persistent "background" emissions that slowly vary as structures in the atmosphere evolve. The latter two processes are coherent mechanisms, which refers to special cases where radiation is efficiently produced at a particular set of frequencies. Coherent mechanisms can produce much larger brightness temperatures (intensities) and are primarily responsible for the intense spikes of radiation called solar radio bursts, which are byproducts of the same processes that lead to other forms of solar activity like solar flares and coronal mass ejections.
Merav Opher is a professor of astronomy at Boston University known for her work on the heliosphere, the cocoon formed by the wind emanated from the Sun as it travels in the Galaxy. In 2021 she was named a William Bentinck-Smith Fellow at the Harvard Radcliffe Institute.
Cynthia Cattell is space plasma physicist known her research on solar flares and radiation belts.
Amitava Bhattacharjee is a theoretical plasma physicist and a professor at Princeton University. He was awarded the 2022 James Clerk Maxwell Prize for Plasma Physics for his work on dusty plasmas and fundamental plasma processes such as magnetic reconnection, magnetohydrodynamic turbulence and dynamo actions, as well as his contributions in connecting laboratory plasmas to astrophysical plasmas.
Gordon Dean Holman is an emeritus research astrophysicist at the National Aeronautics and Space Administration's (NASA’s) Goddard Space Flight Center in Greenbelt, Maryland. His research mostly focused on obtaining an understanding of high-energy radiation from astronomical objects. This radiation cannot be observed from Earth's surface, but is observed with instruments on satellites launched to orbits above Earth's atmosphere. It is primarily emitted by high-energy electrons interacting with ions. These electrons also emit radiation at radio frequencies which is observed from Earth's surface. Consequently, these observations from space and radio telescopes provide a view of hot gas and energetic particles in the Universe that could not otherwise be obtained. Holman has specialized in the interpretation of these observed emissions to determine the origin and evolution of this hot gas and energetic particles. He has been described as "not just a theorist, he also looks at the data".