scholarly journals Time-Resolved Spectra in the 5–330 Å Region Emitted from the PLT and TFTR Tokamak Plasmas

1984 ◽  
Vol 86 ◽  
pp. 171-174
Author(s):  
J.L. Schwob ◽  
A.W. Wouters ◽  
S. Suckewer ◽  
F.P. Boody ◽  
M. Finkenthal
Keyword(s):  
Particle Transport ◽  
Spectral Lines ◽  
Tokamak Plasmas ◽  
Time Resolved ◽  
X Ray ◽  
Radiation Losses ◽  
Transport Studies ◽  
Resonance Transitions ◽  
Metallic Impurities ◽  
Multichannel Spectrometer

The analysis of impurity radiation from Tokamak plasmas is one of the most important diagnostics, allowing the measurement of the impurity concentrations, radiation losses and particle transport studies. This study requires simultaneous time-resolved observation of spectral lines from many ionization states for each element. The most intense and important lines are the He and H-like resonance transitions of Oxygen and Carbon and Δn = 0, 1 transitions of highly ionized metallic impurities. These emmissions have been recorded on PLT and TFTR tokamaks by means of a soft X-ray multichannel spectrometer (SOXMOS).

scholarly journals Investigations concerning plasma parameters and population inversion in laser-produced counterstreaming plasmas

1991 ◽  
Vol 9 (2) ◽  
pp. 501-515 ◽  
Author(s):  
P. Glas ◽  
M. Schnürer
Keyword(s):  
Computational Analysis ◽  
Nuclear Charge ◽  
Gain Coefficient ◽  
Spectral Lines ◽  
Interaction Zone ◽  
Electron Number ◽  
Plasma Parameters ◽  
X Ray ◽  
Spatial Intensity Distribution ◽  
Resonance Transitions

We investigated the case where two laser-produced plasmas collide nearly head on. Special attention was devoted to the fundamentals necessary to realize a coherent X-ray source. A gas-dynamic computational analysis was performed to understand the evolution of the density, the temperature, and the velocity of merging plasmas. The spatial intensity distribution of selected spectral lines reveals that the interaction of plasmas of different nuclear charge and charge state is not strictly collision dominated. Using spectral line intensity ratios, we determined electron temperatures and electron number densities, as well as the intensity inversion on the 4–1 to 3–1 resonance transitions of [He]-like Al. Inversion occurs in the vicinity of the targets if identical materials are used (Al–Al) and is possibly indicated in the interaction zone for different ones (Al–Cu), too. The inversion factors (and the gain coefficient) for the 4–3 transition of [He]-like Al at about 130 Å were estimated.

Temperature and impurity transport studies of heated tokamak plasmas by means of a collisional-radiative model of x-ray emission fromMo30+toMo39+

2000 ◽  
Vol 61 (5) ◽  
pp. 5701-5709 ◽  
Author(s):  
D. Pacella ◽  
K. B. Fournier ◽  
M. Zerbini ◽  
M. Finkenthal ◽  
M. Mattioli ◽  
...  
Keyword(s):  
Tokamak Plasmas ◽  
X Ray ◽  
Transport Studies ◽  
Impurity Transport ◽  
Collisional Radiative Model ◽  
Radiative Model

scholarly journals Photoionized plasmas induced in molecular gases by extreme ultraviolet and X-ray pulses

2018 ◽  
Vol 167 ◽  
pp. 03003
Author(s):  
Andrzej Bartnik ◽  
Wojciech Skrzeczanowski ◽  
Henryk Fiedorowicz ◽  
Przemysław Wachulak ◽  
Tomasz Fok ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Molecular Ions ◽  
Spectral Lines ◽  
Molecular Spectra ◽  
Boltzmann Plot ◽  
Time Resolved ◽  
X Ray ◽  
Molecular Gases ◽  
Low Temperature Plasmas ◽  
Photoionized Plasmas

In this work a laser-produced plasma (LPP) source was used to create low temperature plasmas. An extreme ultraviolet and soft X-ray (EUV/SXR) radiation pulse was used for ionization of molecular gases, injected into a vacuum chamber synchronously with the EUV/SXR pulse. Energies of photons exceeding 100 eV were sufficient for dissociative ionization, ionization of atoms or even ions. The resulting photoelectrons had also enough energy for further ionizations or excitations. Time resolved UV/VIS spectra, corresponding to single charged ions, molecules and molecular ions, were recorded. For spectral lines, corresponding to radiative transitions in F II and S II ions, electron temperature was calculated based on a Boltzmann plot method. Numerical simulations of the molecular spectra were fitted to the experimental spectra allowing for determination of vibrational and rotational temperatures.

scholarly journals X-Ray Spectroscopy of Laser-Produced Plasmas

1984 ◽  
Vol 86 ◽  
pp. 229-233
Author(s):  
Robert L. Kauffman
Keyword(s):  
High Energy ◽  
Spectroscopic Studies ◽  
Spectral Lines ◽  
High Energy Density ◽  
Stark Broadening ◽  
Density Region ◽  
Time Resolved ◽  
X Ray ◽  
Relative Line ◽  
Time Histories

Laser-produced plasmas have some of the highest temperatures and densities obtainable in the laboratory. This offers the opportunity to perform spectroscopic studies in new temperature and density regimes under controlled laboratory conditions. Temperatures can range from greater than 1 keV to less than 1 eV, while densities range from less than 1020e−/cm3 to greater than 1023e−/cm3. X-ray spectroscopy has been an important tool in diagnosing these large ranges of temperature and density. Relative line intensities of resonance and satellite lines can be used to diagnose the lower densities and higher temperatures. (Galanti and Peacock 1975, Boilo et al. 1979) For the denser plasmas Stark broadening is a good density diagnostic. (Yaakobi et al. 1977) Absorption spectroscopy measuring edge shifts had recently been used to probe the low temperature, high density region. These plasmas, with their high-energy density, are transient with total time scales ranging from 100 psec to greater than 1 nsec, depending on the laser driver pulse. In order to make detailed measurements from these plasmas, sensitive, time-resolved spectrographs have been developed. (Lewis et al. 1980, Kauffman et al. 1983) These spectrographs can measure time histories of spectral lines with resolving powers of 300 or greater and with time-resolutions of 20 psec. By using such instruments, studies of the dynamics of the plasma can be made.

scholarly journals The large-scale magnetic field of the eccentric pre-main-sequence binary system V1878 Ori

2020 ◽  
Vol 497 (1) ◽  
pp. 632-642
Author(s):  
A Lavail ◽  
O Kochukhov ◽  
G A J Hussain ◽  
C Argiroffi ◽  
E Alecian ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Mean Field ◽  
Spectral Lines ◽  
Doppler Imaging ◽  
Time Resolved ◽  
X Ray ◽  
T Tauri ◽  
Global Magnetic Field ◽  
Spectrum Synthesis

ABSTRACT We report time-resolved, high-resolution optical spectropolarimetric observations of the young double-lined spectroscopic binary V1878 Ori. Our observations were collected with the ESPaDOnS spectropolarimeter at the Canada–France–Hawaii Telescope through the BinaMIcS large programme. V1878 Ori A and B are partially convective intermediate mass weak-line T Tauri stars on an eccentric and asynchronous orbit. We also acquired X-ray observations at periastron and outside periastron. Using the least-squares deconvolution technique (LSD) to combine information from many spectral lines, we clearly detected circular polarization signals in both components throughout the orbit. We refined the orbital solution for the system and obtained disentangled spectra for the primary and secondary components. The disentangled spectra were then employed to determine atmospheric parameters of the two components using spectrum synthesis. Applying our Zeeman Doppler imaging code to composite Stokes IV LSD profiles, we reconstructed brightness maps and the global magnetic field topologies of the two components. We find that V1878 Ori A and B have strikingly different global magnetic field topologies and mean field strengths. The global magnetic field of the primary is predominantly poloidal and non-axisymmetric (with a mean field strength of 180 G). While the secondary has a mostly toroidal and axisymmetric global field (mean strength of 310 G). These findings confirm that stars with very similar parameters can exhibit radically different global magnetic field characteristics. The analysis of the X-ray data shows no sign of enhanced activity at periastron, suggesting the lack of strong magnetospheric interaction at this epoch.

Microtubule nucleation sequence studied by time-resolved x-ray scattering and electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 766-767
Author(s):  
Eva-Maria Mandelkow ◽  
Eckhard Mandelkow ◽  
Joan Bordas
Keyword(s):  
Electron Microscopy ◽  
Dynamic Equilibrium ◽  
Time Resolved ◽  
X Ray ◽  
Additional Information ◽  
X Ray Scattering ◽  
Low Concentrations ◽  
Microtubule Growth ◽  
Ray Patterns ◽  
Ray Scattering

When a solution of microtubule protein is changed from non-polymerising to polymerising conditions (e.g. by temperature jump or mixing with GTP) there is a series of structural transitions preceding microtubule growth. These have been detected by time-resolved X-ray scattering using synchrotron radiation, and they may be classified into pre-nucleation and nucleation events. X-ray patterns are good indicators for the average behavior of the particles in solution, but they are difficult to interpret unless additional information on their structure is available. We therefore studied the assembly process by electron microscopy under conditions approaching those of the X-ray experiment. There are two difficulties in the EM approach: One is that the particles important for assembly are usually small and not very regular and therefore tend to be overlooked. Secondly EM specimens require low concentrations which favor disassembly of the particles one wants to observe since there is a dynamic equilibrium between polymers and subunits.

Current Status of Solid-State X-Ray Systems

1985 ◽  
Vol 43 ◽  
pp. 158-161
Author(s):  
Martin Peckerar ◽  
Anastasios Tousimis
Keyword(s):  
Solid State ◽  
Electric Fields ◽  
Spectral Lines ◽  
Current Status ◽  
Mobile Charge ◽  
Electron Hole ◽  
X Ray ◽  
Sensing Systems ◽  
Transmission Electron ◽  
Electron Microscopes

Solid state x-ray sensing systems have been used for many years in conjunction with scanning and transmission electron microscopes. Such systems conveniently provide users with elemental area maps and quantitative chemical analyses of samples. Improvements on these tools are currently sought in the following areas: sensitivity at longer and shorter x-ray wavelengths and minimization of noise-broadening of spectral lines. In this paper, we review basic limitations and recent advances in each of these areas. Throughout the review, we emphasize the systems nature of the problem. That is. limitations exist not only in the sensor elements but also in the preamplifier/amplifier chain and in the interfaces between these components.Solid state x-ray sensors usually function by way of incident photons creating electron-hole pairs in semiconductor material. This radiation-produced mobile charge is swept into external circuitry by electric fields in the semiconductor bulk.

Electron probe x-ray microanalysis and electron microscopy of amino acid absorption and transport by the small intestine: inhibition by chemical poisons and correlation to the elemental composition of the epithelial cells

1986 ◽  
Vol 44 ◽  
pp. 134-135
Author(s):  
A. J. Tousimis
Keyword(s):  
Small Intestine ◽  
Amino Acid ◽  
Epithelial Cells ◽  
Elemental Composition ◽  
Isotope Labeling ◽  
Structural Components ◽  
X Ray ◽  
Human Small Intestine ◽  
Transport Studies

The elemental composition of amino acids is similar to that of the major structural components of the epithelial cells of the small intestine and other tissues. Therefore, their subcellular localization and concentration measurements are not possible by x-ray microanalysis. Radioactive isotope labeling: I131-tyrosine, Se75-methionine and S35-methionine have been successfully employed in numerous absorption and transport studies. The latter two have been utilized both in vitro and vivo, with similar results in the hamster and human small intestine. Non-radioactive Selenomethionine, since its absorption/transport behavior is assumed to be the same as that of Se75- methionine and S75-methionine could serve as a compound tracer for this amino acid.

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