634 research outputs found
Magnetic Field Generation from Self-Consistent Collective Neutrino-Plasma Interactions
A new Lagrangian formalism for self-consistent collective neutrino-plasma
interactions is presented in which each neutrino species is described as a
classical ideal fluid. The neutrino-plasma fluid equations are derived from a
covariant relativistic variational principle in which finite-temperature
effects are retained. This new formalism is then used to investigate the
generation of magnetic fields and the production of magnetic helicity as a
result of collective neutrino-plasma interactions.Comment: 23 page
A wide bandwidth free-electron laser with mode locking using current modulation
A new scheme for mode locking a free-electron laser (FEL) amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept (Thompson and McNeil 2008 Phys. Rev. Lett. 100 203901), based on the energy modulation of electrons, are improved, including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked FEL and a self-amplified spontaneous emission FEL. Illustrative examples using a hypothetical mode-locked FEL amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated
Phase-locking transition in a chirped superconducting Josephson resonator
By coupling a harmonic oscillator to a quantum system it is possible to
perform a dispersive measurement that is quantum non-demolition (QND), with
minimal backaction. A non-linear oscillator has the advantage of measurement
gain, but what is the backaction? Experiments on superconducting quantum bits
(qubits) coupled to a non-linear Josephson oscillator have thus far utilized
the switching of the oscillator near a dynamical bifurcation for sensitivity,
and have demonstrated partial QND measurement. The detailed backaction
associated with the switching process is complex, and may ultimately limit the
degree to which such a measurement can be QND. Here we demonstrate a new
dynamical effect in Josephson oscillators by which the bifurcation can be
accessed without switching. When energized with a frequency chirped drive with
an amplitude close to a sharp, phase-locking threshold, the oscillator evolves
smoothly in one of two diverging trajectories - a pointer for the state of a
qubit. The observed critical behavior agrees well with theory and suggests a
new modality for quantum state measurement.Comment: 5 pages, 4 figure
Transparency of Magnetized Plasma at Cyclotron Frequency
Electromagnetic radiation is strongly absorbed by the magnetized plasma if its frequency equals the cyclotron frequency of plasma electrons. It is demonstrated that absorption can be completely canceled in the presence of a second radiation beam, or even a magnetostatic field of an undulator, resulting in plasma transparency at the cyclotron frequency. This effect is reminiscent of the electromagnetically-induced transparency (EIT) of the three-level atomic systems, except that it occurs in a completely {\it classical} plasma. Also, because of the complexity of the classical plasma, index of refraction at cyclotron frequency differs from unity. Potential applications of the EIT in plasma include selective plasma heating, electromagnetic control of the index of refraction, and electron/ion acceleration
Meta!Blast computer game: a pipeline from science to 3D art to education
Meta!Blast (http://www.metablast.org) is designed to address the challenges students often encounter in understanding cell and metabolic biology. Developed by faculty and students in biology, biochemistry, computer science, game design, pedagogy, art and story, Meta!Blast is being created using Maya (http://usa.autodesk.com/maya/) and the Unity 3D (http://unity3d.com/) game engine, for Macs and PCs in classrooms; it has also been exhibited in an immersive environment. Here, we describe the pipeline from protein structural data and holographic information to art to the threedimensional (3D) environment to the game engine, by which we provide a publicly-available interactive 3D cellular world that mimics a photosynthetic plant cell
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