On the Ability of an Extreme-Ultraviolet Multilayer Normal-Incidence Telescope to Provide Temperature Information for Solar Plasmas

1999 ◽  
Vol 511 (1) ◽  
pp. L61-L64 ◽  
Author(s):  
U. Feldman ◽  
J. M. Laming ◽  
G. A. Doschek ◽  
H. P. Warren ◽  
L. Golub
Keyword(s):  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Solar Plasmas

scholarly journals Experiment to Determine the Temperature Structure in the Solar Chromosphere and Corona

1972 ◽  
Vol 14 ◽  
pp. 668-669
Author(s):  
C. R. Negus
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Research Unit ◽  
Emission Lines ◽  
Solar Chromosphere ◽  
Temperature Structure ◽  
Ultraviolet Emission ◽  
Ionization Temperature ◽  
Intensity Ratios

An experiment is in course of preparation at the Astrophysics Research Unit at Culham for flight on a Sun-pointing rocket. It is designed to determine the ionization temperature and electron density as a function of height in the temperature range of about 8 × 104 K to 3 × 106 K by measuring limb to disk intensity ratios of extreme ultraviolet emission lines in the 170 to 850 Å region. The work is an extension of current experiments in which normal-incidence spectrographs are used to determine the structure lower in the chromosphere-corona transition region.

Normal-incidence efficiencies of multilayer-coated laminar gratings for the Extreme-Ultraviolet Imaging Spectrometer on the Solar-B mission

2004 ◽  
Vol 43 (7) ◽  
pp. 1463 ◽  
Author(s):  
John F. Seely ◽  
Charles M. Brown ◽  
David L. Windt ◽  
Soizik Donguy ◽  
Benjawan Kjornrattanawanich
Keyword(s):  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Imaging Spectrometer

Near-normal-incidence extreme-ultraviolet efficiency of a flat crystalline anisotropically etched blazed grating

2006 ◽  
Vol 45 (8) ◽  
pp. 1676 ◽  
Author(s):  
Michael P. Kowalski ◽  
Ralf K. Heilmann ◽  
Mark L. Schattenburg ◽  
Chih-Hao Chang ◽  
Frederick B. Berendse ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Blazed Grating

Normal Incidence Multilayer Mirrors For Extreme Ultraviolet Astronomy

1984 ◽  
Author(s):  
Robert A. Stern ◽  
Bernhard M. Haisch ◽  
George Joki ◽  
Richard C. Catura
Keyword(s):  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Multilayer Mirrors ◽  
Ultraviolet Astronomy

scholarly journals Far and Extreme Ultraviolet Astronomy with Orfeus

1990 ◽  
Vol 123 ◽  
pp. 177-184
Author(s):  
G. Krämer ◽  
J. Barnstedt ◽  
N. Eberhard ◽  
M. Grewing ◽  
W. Gringel ◽  
...  
Keyword(s):  
Spectral Range ◽  
White Dwarf ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Ultraviolet Astronomy ◽  
Range Resolution ◽  
Spectroscopic Investigations ◽  
Ultraviolet Spectrometer

AbstractORFEUS (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer) is a 1 m normal incidence telescope for spectroscopic investigations of cosmic sources in the far and extreme ultraviolet spectral range. The instrument will be integrated into the freeflyer platform ASTRO-SPAS. ORFEUS-SPAS is scheduled with STS ENDEAVOUR in September 1992. We describe the telescope with its two spectrometers and their capabilities i.e. spectral range, resolution and overall sensitivity. The main classes of objects to be observed with the instrument are discussed and two examples of simulated spectra for the white dwarf HZ43 and an O9-star in the LMC are shown.

scholarly journals The Solar EUV-Emitting Plasma

1972 ◽  
Vol 14 ◽  
pp. 612-637
Author(s):  
R. W. Noyes ◽  
G. L. Withbroe
Keyword(s):  
Acoustic Waves ◽  
Energy Transport ◽  
Extreme Ultraviolet ◽  
Magnetic Energy ◽  
Solar Spectrum ◽  
Visible Spectrum ◽  
Normal Incidence ◽  
Complex Situation ◽  
Physical Conditions ◽  
Energy Balances

The extreme ultraviolet (EUV) solar spectrum is considered in this review to cover a decade in wavelength from about 300 Å to about 3000 Å. The lower end is close to the practical limit of normal-incidence optics, and the upper end is the approximate limit of visibility from Earth’s surface. The solar plasma that gives rise to emission within this interval is very complex and covers a huge range of physical conditions. Temperatures range from about 4 × 103 K (the temperature minimum in the low chromosphere, observed in the 1600 Å continuum) to about 4 × 106 K. (corresponding to emission of the FeXVI doublet at 335 and 361 Å). The density of the emitting plasma ranges from 1015 cm-3 in the upper photosphere to 108 cm-3 in the quiet corona. Major types of energy transport and deposition within the plasma include not only radiation, but also acoustic waves, magnetohydrodynamic waves, thermal conduction, and convective flow. Magnetic energy often completely controls detailed structure and energy balances within the plasma. Inhomogeneities are not a small perturbation on the overall structure of the plasma, but rather may completely dominate that structure. Extreme departures from local thermodynamic equilibrium (LTE) are the rule rather than the exception. (It is interesting to contrast this complex situation with that seen in the next wavelength decade, from 3000 Å to 3 μ, which includes the visible spectrum. With the exception of a few strong chromospheric lines, this radiation emerges from a comparatively isothermal (5000 K<T<6000 K), horizontally homogeneous, atmosphere in hydrostatic and radiative equilibrium, in which LTE is the rule rather than the exception.)

scholarly journals Vacuum Ultraviolet Absorption of Dense Plasmas with Resonance Series of Be, B, C, N, Mg, Al and Si

1972 ◽  
Vol 14 ◽  
pp. 531-531
Author(s):  
G. Mehlman-Balloffet ◽  
J. M. Esteva
Keyword(s):  
Vacuum Ultraviolet ◽  
Extreme Ultraviolet ◽  
Light Element ◽  
Numerical Data ◽  
Normal Incidence ◽  
Electron Excitation ◽  
Rydberg Series ◽  
Dense Plasmas ◽  
Continuous Background ◽  
Ionization Limit

AbstractAbsorption spectra of light elements were observed in the vacuum ultraviolet with an original technique described in an earlier paper (Mehlman-Balloffet and Esteva, 1969). The method utilizes a two-vacuum spark mounting: one of the sparks is emitting the continuous background, the other one generates the absorbing plasma. Several light element have been successsively introduced in the spark anode. For all of them new autoionizing levels have been observed in Rydberg series of resonances exhibiting the asymmetric ‘Beutler-Fano’ profile.In the beryllium and magnesium spectra three new series corresponding to two-electron excitation process have been identified while for boron, carbon, nitrogen, aluminium and silicon the resonances observed correspond to single subshell electron excitation such as: 2s22p2P0 → 2s2p(3P0)np2De for the case of boron.All these series lie in the photoionization continuum of the absorbing atomic species and usually between the first and second ionization limit. This means that they were observed with a normal incidence grating spectrograph in the spectral range 500–1500 Å. In the extreme ultraviolet some other transitions involving inner-shell electron excitation were observed. In the beryllium spectra a series lying between 100 and 110 Å was identified while, the magnesium spectra exhibited only isolated resonances in the 220-265 Å range together with an inner-shell 2p electron photoioniation continuum.A complete description of experimental results with numerical data is being submitted for publication (Esteva and Mehlman-Balloffet, 1972).

scholarly journals Solar EUV Photoelectric Observations from Skylab

1974 ◽  
Vol 57 ◽  
pp. 497-500
Author(s):  
E. M. Reeves ◽  
P. V. Foukal ◽  
M. C. E. Huber ◽  
R. W. Noyes ◽  
E. J. Schmahl ◽  
...  
Keyword(s):  
Solar Atmosphere ◽  
Extreme Ultraviolet ◽  
Three Dimensional ◽  
Active Regions ◽  
Normal Incidence ◽  
Ionic Species ◽  
Ultraviolet Region ◽  
Spatial Image ◽  
Lyman Continuum ◽  
Solar Blind

Most of the atomic species originating in the solar atmosphere between the upper chromosphere and the corona have their strong characteristic wavelengths in the extreme ultraviolet region of the spectrum. A simple normal-incidence spectrometer system with solar blind detectors such as the Harvard instrument operating between approximately 250 Å and 1350 Å is ideally suited for observing in this most interesting range of the solar atmosphere where the temperature rises outward from 104 to 3 × 106 K. The temperature range represented by the various atomic and ionic species in the extreme ultraviolet is associated with many types of solar structure, prominences and filaments, the supergranulation cells and network, active regions and their associated loop structures and other features. Simultaneous observations in lines of different characteristic temperatures provide a three-dimensional probe of the solar atmosphere. In the instrument, the principal polychromatic position observes the Lyman continuum, Lα, C II, C III, O IV, O VI, and Mg x with seven detectors simultaneously from the same spatial image element, 5″ in size. Approximately 60 additional polychromatic positions are used routinely to carry out specific observing programs, for example, covering several lines of a given stage of ionization, observing lines or continuum from specific species of interest such as helium in prominences, comparing combinations of lines from a given ionic species such as O v where the relative intensities give a rather direct measurement of the density at a given temperature, or measuring differing positions in the Lyman continuum providing intensity measurements which can be interpreted in terms of the departure from ionization equilibrium.

Enhancement of multilayer-coated normal incidence gratings in the extreme ultraviolet using a CN x smoothing layer

2003 ◽  
Author(s):  
Robert A. Stern ◽  
Lawrence Shing ◽  
Yip-Wah Chung ◽  
Murat U. Guruz
Keyword(s):  
Extreme Ultraviolet ◽  
Normal Incidence
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