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A novel type of particle "cooling", called Ionization Cooling, is applicable to slow (v of the order of 0.1c) ions stored in a small ring. The many traversals through a thin foil enhance the nuclear reaction probability, in a steady…

High Energy Physics - Phenomenology · Physics 2011-05-18 C. Rubbia , A. Ferrari , Y. Kadi , V. Vlachoudis

Turbulence is a predominant process for energizing electrons and ions in collisionless astrophysical plasmas, and thus is responsible for shaping their radiative signatures (luminosity, spectra, and variability). To better understand the…

High Energy Astrophysical Phenomena · Physics 2021-02-24 Vladimir Zhdankin , Dmitri A. Uzdensky , Matthew W. Kunz

Using high-resolution numerical simulations we investigate the plasma heating driven by periodic two-fluid acoustic waves that originate at the bottom of the photosphere and propagate into the gravitationally stratified and partially…

Solar and Stellar Astrophysics · Physics 2019-06-26 B. Kuźma , D. Wójcik , K. Murawski

We report on an X-ray flare detected on the active binary system II~Pegasi with the Swift telescope. The trigger had a 10-200 keV luminosity of 2.2$\times10^{32}$ erg s$^{-1}$-- a superflare, by comparison with energies of typical stellar…

Astrophysics · Physics 2008-11-26 R. A. Osten , S. Drake , J. Tueller , J. Cummings , M. Perri , A. Moretti , S. Covino

The steep power-law dependence of element abundance enhancements on the mass-to-charge ratios [A/Q] of the ions in impulsive solar energetic-particle (SEP) events causes these enhancements to reflect the temperature-dependent pattern of Q…

Solar and Stellar Astrophysics · Physics 2015-10-05 Donald V. Reames , Edward W. Cliver , Stephen W. Kahler

A flux rope eruption on September 10, 2017 provides unique observations of the plasma sheet beneath the rising flux rope. The plasma sheet is likely in a nonequilibrium state in terms of both ionization and the electron distribution…

Solar and Stellar Astrophysics · Physics 2026-04-03 Jin-Yi Lee , John C. Raymond , Katharine K. Reeves , Chengcai Shen , Stephen Kahler , Yong-Jae Moon , Yeon-Han Kim

This work follows Lykins et al. discussion of classic plasma cooling function at low density and solar metallicity. Here we focus on how the cooling function changes over a wide range of density (n_H<10^12 cm^(-3)) and metallicity (Z<30Z…

Instrumentation and Methods for Astrophysics · Physics 2014-05-12 Ye Wang , G. J. Ferland , M. L. Lykins , R. L. Porter , P. A. M. van Hoof , R. J. R. Williams

We study the long-time evolution of the ion temperature in an expanding ultracold neutral plasma using spatially resolved, laser-induced-fluorescence spectroscopy. Adiabatic cooling reduces the ion temperature by an order of magnitude…

Plasma Physics · Physics 2015-06-23 P. McQuillen , T. Strickler , T. Langin , T. C. Killian

High-energy-density flows through dense matter are needed for effective progress in the production of laser-driven intense sources of energetic particles and radiation, in driving matter to extreme temperatures creating state regimes…

Direct laser acceleration (DLA) of electrons in a plasma of near critical electron density (NCD) and associated synchrotron-like radiation are discussed for moderate relativistic laser intensity (the normalized laser amplitude $a_0$ $\leq$…

Scattering relativistic electrons with optical lasers can result in a significant frequency upshift for the photons, potentially producing $\gamma$-rays. This is what linear Compton scattering taught us. Ultra-intense lasers offer nowadays…

Plasma Physics · Physics 2019-06-05 Marija Vranic , Thomas Grismayer , Sebastian Meuren , Ricardo A. Fonseca , Luis O. Silva

The extreme ultraviolet (XUV) emission from dense plasmas generated with sub-10-fs laser pulses with varying peak intensities up to 3*10^16 W/cm^2 is investigated for different target materials. K shell spectra are obtained from low Z…

Plasma Physics · Physics 2009-11-13 J. Osterholz , F. Brandl , M. Cerchez , T. Fischer , D. Hemmers , B. Hidding , A. Pipahl , G. Pretzler , S. J. Rose , O. Willi

The ultrafast laser-induced solid-liquid phase transition in metals is still not clearly understood and its accurate quantitative description remains a challenge. Here we systematically investigated, both experimentally and theoretically,…

It is generally accepted that densities of quiet sun and active region plasma are sufficiently low to justify the optically thin approximation, and it is commonly used in the analysis of line emissions from plasma in the solar corona.…

Solar and Stellar Astrophysics · Physics 2018-02-14 Edward Thiemann , Phillip Chamberlin , Francis Eparvier , Luke Epp

We compute the hard X-ray spectra from a hot plasma pervaded by small cold dense clouds. The main cooling mechanism of the plasma is Compton cooling by the soft thermal emission from the clouds. We compute numerically the equilibrium…

Astrophysics · Physics 2009-11-07 Julien Malzac , Annalisa Celotti

The properties of high energy density plasma are under increasing scrutiny in recent years due to their importance to our understanding of stellar interiors, the cores of giant planets$^{1}$, and the properties of hot plasma in inertial…

In simulations of a 10PW laser striking a solid we demonstrate the possibility of producing a pure electron-positron plasma by the same processes as those thought to operate in high-energy astrophysical environments. A maximum positron…

We discuss recent improvements in the calculation of the radiative cooling in both collisionally and photo ionized plasmas. We are extending the spectral simulation code Cloudy so that as much as possible of the underlying atomic data is…

High Energy Astrophysical Phenomena · Physics 2015-06-12 M. L. Lykins , G. J. Ferland , Ryan L. Porter , Peter A. M. van Hoof , R. J. R. Williams , Orly Gnat

We demonstrate the potential of X-ray free-electron lasers (XFEL) to advancethe understanding of complex plasma dynamics by allowing for the first time nanometer and femtosecond resolution at the same time in plasma diagnostics. Plasma…

The study of the localized plasma conditions before the impulsive phase of a solar flare can help us understand the physical processes that occur leading up to the main flare energy release. Here, we present evidence of a hot X-ray onset…

Solar and Stellar Astrophysics · Physics 2020-12-02 Hugh S. Hudson , Paulo J. A. Simoes , Lyndsay Fletcher , Laura A. Hayes , Iain G. Hannah