scholarly journals The role of photo-ionization in extreme ultraviolet ablation interactions

2021 ◽  
Author(s):  
James A. Lolley ◽  
Greg J. Tallents
Keyword(s):  
Extreme Ultraviolet ◽  
Photo Ionization

scholarly journals Theoretical Implications of Diffuse Non-Thermal Emission from Clusters of Galaxies

2002 ◽  
Vol 199 ◽  
pp. 141-148
Author(s):  
T.A. Enßlin
Keyword(s):  
Thermal Emission ◽  
Extreme Ultraviolet ◽  
Short Review ◽  
Radio Galaxies ◽  
High Energy ◽  
Clusters Of Galaxies ◽  
Thermal Electron ◽  
Electron Population ◽  
X Ray

A short review on theoretical implications of non-thermal emission (radio, extreme ultraviolet, high energy X-ray) from the intra-cluster medium is given. The origin of cluster radio halos and cluster radio relics is discussed within the framework of a network of processes producing a non-thermal electron population. Emphasis is given to the role of old, remnant, presently invisible relativistic plasma released by former radio galaxies.

scholarly journals Calcium and Potassium Spectra in the EUV

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 73
Author(s):  
Elmar Träbert
Keyword(s):  
Survey Data ◽  
Extreme Ultraviolet ◽  
Single Element ◽  
Data Bases ◽  
Online Data ◽  
Solar Observations ◽  
Multiply Charged ◽  
Ca Ions ◽  
Beam Foil

In online data bases, the entries on extreme ultraviolet (EUV) spectra of Ca are much more sparse than those of neighbouring elements such as Ar, K, Sc and Ti. This may be a result of experimental problems with Ca in the laboratory as well as of the limited role of multiply charged Ca ions in solar observations. Beam-foil EUV spectra of Ca and K are presented that provide survey data of a single element each.

scholarly journals The Composition and Structure of White Dwarf Atmospheres Revealed by Extreme Ultraviolet Spectroscopy

1996 ◽  
Vol 152 ◽  
pp. 203-210
Author(s):  
Martin A. Barstow ◽  
Ivan Hubeny ◽  
Thierry Lanz ◽  
Jay B. Holberg ◽  
Edward M. Sion
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Extreme Ultraviolet ◽  
Important Change ◽  
Heavy Elements ◽  
Composition And Structure ◽  
Crucial Test ◽  
Central Stars ◽  
Quantitative Consideration

The ROSAT and EUVE all-sky surveys have resulted in an important change in our understanding of the general composition of hydrogen-rich DA white dwarf atmospheres, with the photospheric opacity dominated by heavy elements rather than helium in the hottest stars (T > 40, 000 K). Most stars cooler than 40,000 K have more or less pure H atmospheres. However, one question, which has not been resolved, concerned the specific nature of the heavy elements and the role of helium in the hottest white dwarfs. One view of white dwarf evolution requires that H-rich DA stars form by gravitational settling of He from either DAO or He-rich central stars of planetary nebulae. In this case, the youngest (hottest) DA white dwarfs may still contain visible traces of He. Spectroscopic observations now available with EUVE provide a crucial test of these ideas. Analysis of data from the EUVE Guest Observer programme and EUVE public archive allows quantitative consideration of the sources of EUV opacity and places limits on the abundance of He which may be present.

scholarly journals The Role of Electron Trajectories in XUV-Initiated High-Harmonic Generation

2019 ◽  
Vol 9 (3) ◽  
pp. 378 ◽  
Author(s):  
Michael Krüger ◽  
Doron Azoury ◽  
Barry Bruner ◽  
Nirit Dudovich
Keyword(s):  
Harmonic Generation ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Generation Process ◽  
Electron Trajectories ◽  
Tunneling Ionization ◽  
Spectral Frequency ◽  
And Control

High-harmonic generation spectroscopy is a powerful tool for ultrafast spectroscopy with intrinsic attosecond time resolution. Its major limitation—the fact that a strong infrared driving pulse is governing the entire generation process—is lifted by extreme ultraviolet (XUV)-initiated high-harmonic generation (HHG). Tunneling ionization is replaced by XUV photoionization, which decouples ionization from recollision. Here we probe the intensity dependence of XUV-initiated HHG and observe strong spectral frequency shifts of the high harmonics. We are able to tune the shift by controlling the instantaneous intensity of the infrared field. We directly access the reciprocal intensity parameter associated with the electron trajectories and identify short and long trajectories. Our findings are supported and analyzed by ab initio calculations and a semiclassical trajectory model. The ability to isolate and control long trajectories in XUV-initiated HHG increases the range of the intrinsic attosecond clock for spectroscopic applications.

Role of Current and Magnetic Field Structure at Directed Extreme Ultraviolet Generation in Plasma Discharge for Nano-Lithography

2010 ◽  
Author(s):  
V. I. Maslov ◽  
N. A. Azarenkov ◽  
A. Hassanein ◽  
D. V. Riabchikov ◽  
O. M. Svistun ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Plasma Discharge ◽  
Field Structure ◽  
Magnetic Field Structure

scholarly journals First Year of Observations with SOHO/EIT of the “Quiet” Sun Corona

1998 ◽  
Vol 167 ◽  
pp. 41-44
Author(s):  
F. Portier-Fozzani ◽  
A.J. Maucherat ◽  
EIT Team
Keyword(s):  
Extreme Ultraviolet ◽  
Coronal Holes ◽  
Active Regions ◽  
Emission Lines ◽  
Magnetic Interactions ◽  
First Year ◽  
Wide Field ◽  
Morphology Evolution ◽  
Magnetic Structures

AbstractSince January 1996 (EIT first light) the Extreme Ultraviolet Telescope aboard SOHO has produced about 20,000 wide-field images of the corona and transition regions. Four different emission lines (He II, Fe IX/X, Fe XII, Fe XV) were selected to detail morphologies of magnetic structures in the corona. They show the different structures present in the corona with information about their topologies (Neupert et al. 1998). They provide the global temperature distribution in the quiet corona in the range 0.5 to 3 × 106 K.The evolution of the corona during the first year of the SOHO mission revealed its nonuniform aspect and the nonregularity of the appearance of new active regions. Changes observed in active regions and coronal holes (e.g., August–September 1996) showed the complex role of magnetic fields including magnetic interactions and possible reconnections needed to explain some loop morphology evolution.

scholarly journals Active Late-Type Stellar Coronae: Hints for Flare Heating?

2000 ◽  
Vol 195 ◽  
pp. 377-378 ◽  
Author(s):  
M. Audard ◽  
M. Güdel ◽  
J. J. Drake ◽  
V. Kashyap ◽  
E. F. Guinan
Keyword(s):  
Thermal Energy ◽  
Spectral Type ◽  
Extreme Ultraviolet ◽  
Coronal Heating ◽  
Data Archive ◽  
Late Type ◽  
Energy Distributions ◽  
X Ray ◽  
Type Classification

The Extreme Ultraviolet Explorer data archive has been used to study flare energy distributions and infer the role of flares in coronal heating. We have constructed flare number distributions as a function of observed EUV and X-ray emitted thermal energy. We find cumulative flare distributions of the form N(> E) ∝ E−α+1 with α ≍ 1.5–2.6. We present results in the context of spectral type classification.

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