A relativistic plasma shutter technique is proposed and tested to remove the sub-100 ps pedestal of a high-intensity laser pulse. The shutter is an ultrathin foil placed before the target of interest. As the leading edge of the laser ionizes the shutter material it will expand into a relativistically underdense plasma allowing for the peak pulse to propagate through while rejecting the low intensity pedestal. An increase in the laser temporal contrast is demonstrated by measuring characteristic signatures in the accelerated proton spectra and directionality from the interaction of 30 TW pulses with ultrathin foils along with supporting hydrodynamic and particle-in-cell simulations.
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http://dx.doi.org/10.1063/1.3139860 | DOI Listing |
Nat Commun
January 2025
NASA Goddard Space Flight Center, Heliophysics Science Division, Greenbelt, MD, USA.
Shock waves, the interface of supersonic and subsonic plasma flows, are the primary region for charged particle acceleration in multiple space plasma systems, including Earth's bow shock, which is readily accessible for in-situ measurements. Spacecraft frequently observe relativistic electron populations within this region, characterized by energy levels surpassing those of solar wind electrons by a factor of 10,000 or more. However, mechanisms of such strong acceleration remain elusive.
View Article and Find Full Text PDFWe report on continuous high-harmonic generation (HHG) at 1 kHz repetition rate from a liquid-sheet plasma mirror driven by relativistic-intensity near-single-cycle light transients. Through precise control of both the surface plasma density gradient and the driving light waveform, we can produce highly stable and reproducible extreme ultraviolet spectral quasi-continua, expected to correspond to the generation of stable kHz-trains of isolated attosecond pulses in the time domain. This confirms the exciting potential of liquid-sheet targets as one of the building blocks of future high-power attosecond lasers.
View Article and Find Full Text PDFPhys Rev E
November 2024
Department of Physics "A. Pontremoli," University of Milan, via Celoria 16, 20133 Milan, Italy and Institute of Theoretical Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
The shear viscosity is a fundamental transport property of matter. Here we derive a general theory of the viscosity of gases based on the relativistic Langevin equation (deduced from a relativistic Lagrangian) and nonaffine linear response theory. The proposed relativistic theory is able to recover the viscosity of nonrelativistic classical gases, with all its key dependencies on mass, temperature, particle diameter, and Boltzmann constant, in the limit of Lorentz factor γ=1.
View Article and Find Full Text PDFRev Mod Plasma Phys
December 2024
Institut für Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany.
The concept of electromotive field appears in various applications in space and astrophysical plasmas. A review is given on the electromotive field highlighting our current understanding of the theoretical picture and the spacecraft observations in interplanetary space. The electromotive field is a key concept to successfully close the set of turbulent magnetohydrodynamic equations and also to construct a more complete picture of space plasma turbulence.
View Article and Find Full Text PDFHuman activity influence Earth's environment, including the space environment hundreds to thousands of kilometers above the Earth. One direct evidence is that the 19.8 kHz electromagnetic signals launched by the North West Cape (NWC) transmitter station in Australia produce a wisp-like energy distribution of precipitating energetic electrons in Earth's inner radiation belt, observed by many Low Earth Orbiting satellites.
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