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We study high order harmonics generation (HHG) in crystalline silicon and diamond subjected to near and mid-infrared laser pulses. We employ time-dependent density functional theory and solve the time-dependent Kohn-Sham equation in the…

Materials Science · Physics 2022-08-31 David Freeman , Shunsuke Yamada , Atsushi Yamada , Kazuhiro Yabana , Anatoli Kheifets

The understanding of the physics of lasermatter interactions in the strongly relativistic regime is of fundamental importance. In this article, a new mechanism of fast electron generation at the vacuum-solid boundary of intense laser pulse…

Plasma Physics · Physics 2010-09-07 T. Baeva , S. Gordienko , A. P. L. Robinson , P. A. Norreys

Plasmas with anisotropic electron velocity distribution functions are needed for the controlled study of kinetic plasma instabilities in the laboratory. We demonstrate that such plasma can be produced using ultrashort laser pulses via…

Plasma Physics · Physics 2020-05-14 C. K. Huang , C. J. Zhang , K. A. Marsh , C. E. Clayton , C. Joshi

Recent X-ray observations by the space mission Chandra confirmed the astonishing evidence for a diffuse, hot, thermal plasma at a temperature of 9. $10^7$ K (8 keV) found by previous surveys to extend over a few hundred parsecs in the…

Astrophysics · Physics 2009-11-11 R. Belmont , M. Tagger , M. Muno , M. Morris , S. Cowley

Terahertz pulse generation by ultra-intense two-color laser fields ionizing gases with near- to far-infrared carrier wavelength is studied from particle-in-cell (PIC) simulations. For long wavelength ($10.6\ \mu$m) promoting a large ratio…

Plasma Physics · Physics 2020-01-01 J. Déchard , X. Davoine , L. Bergé

Very hot plasmas with ion temperature exceeding $10^{10}$ K can be formed in certain astrophysical environments. The distinct radiation signature of such plasmas is the $\gamma$-ray emission dominated by the prompt de-excitation nuclear…

High Energy Astrophysical Phenomena · Physics 2019-03-29 Ervin Kafexhiu , Felix Aharonian , Maxim Barkov

Plasmas generated using energetic electron beams are well known for their low electron temperature ($T_{e}$) and plasma potential, which makes them attractive for atomic-precision plasma processing applications such as atomic layer etch and…

Plasma Physics · Physics 2023-06-07 Shahid Rauf , D. Sydorenko , S. Jubin , W. Villafana , S. Ethier , A. Khrabrov , I. Kaganovich

A new effect of electromagnetic radiation generated by heat flow in superfluid helium has been detected experimentally. The generating heat flow was produced using hydrodynamic thermal guns. Electromagnetic radiation was registered with a…

Other Condensed Matter · Physics 2008-11-20 A. S. Rybalko , S. P. Rubets , E. Ya. Rudavskii , V. A. Tikhiy , R. Golovachenko , V. N. Derkach , S. I. Tarapov

We report the results of a search for molecular oxygen (O2) toward the Orion Bar, a prominent photodissociation region at the southern edge of the HII region created by the luminous Trapezium stars. We observed the spectral region around…

Sub-femtosecond x-ray burst is powerful tool for probing and imaging electronic and concomitant atomic motion in attosecond physics. For years, x-ray source (above 2 keV) had mainly been obtained from X-ray free electron laser (XFEL) or…

We demonstrate through experiments and numerical simulations that low-density, low-loss, meter-scale plasma channels can be generated by employing a conditioning laser pulse to ionize the neutral gas collar surrounding a hydrodynamic…

An influence of a high-voltage (3-17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1-10 Pa) capacitively-coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic…

Methods: The microscopic equations of H2-formation and protonation are integrated numerically over time in such a manner that the overall structures evolve self-consistently under benign conditions. Results: The equilibrium H2 formation…

Astrophysics of Galaxies · Physics 2009-11-13 H. S. Liszt

We report on the discovery of compact, narrow OH line emission from the hydroxl molecule at 1720 MHz toward the extended TeV source J1834-087. The origin of this high energy emission is unknown; it could be powered by one or more candidate…

High Energy Astrophysical Phenomena · Physics 2015-06-16 D. A. Frail , M. J. Claussen , J. Mehault

A 13.56 MHz RF discharge in hydrogen was studied within the pressure range of 1-17 10 Pa, and at power range of 400-1000 W. The electron energy distribution function and 18 electron density were measured by a Langmuir probe. The gas…

Plasma Physics · Physics 2019-11-11 J Krištof , A Annušová , M Anguš , P. Veis , X Yang , T Angot , P. Roubin , G. Cartry

OH is a cornerstone molecule in the chemistry of interstellar and circumstellar media and is ubiquitously detected in warm gas thanks to its infrared rotational lines. However, the excitation processes of OH remain poorly characterized. We…

The mixing of N2 with H2 leads to very different plasmas from pure N2 and H2 plasma discharges. Numerous issues are therefore raised involving the processes leading to ammonia (NH3) formation. The aim of this work is to better characterize…

We demonstrate unexpectedly strong second harmonic generation (SHG) in Argon gas by use of spatiotemporally focused (SF) femtosecond laser pulses. The resulting SHG by the SF scheme at a 75 cm distance shows a significantly enhanced…

We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the…

Astrophysics · Physics 2009-11-13 S. Viti , T. W. Hartquist , P. C. Myers

To maximize the charge of a high-energy electron beam accelerated by an ultra-intense laser pulse propagating in a subcritical plasma, the pulse length should be longer than both the plasma wavelength and the laser pulse width, which is…

Plasma Physics · Physics 2020-01-08 V. Yu. Bychenkov , M. G. Lobok , V. F. Kovalev , A. V. Brantov