Smooth transition from spectral lines to a continuum in dense hydrogen plasma

2016 ◽  
Vol 54 (1) ◽  
pp. 5-10 ◽  
Author(s):  
L. G. D’yachkov
2014 ◽  
Vol 5 ◽  
pp. 1186-1192 ◽  
Author(s):  
Peter Feng ◽  
Muhammad Sajjad ◽  
Eric Yiming Li ◽  
Hongxin Zhang ◽  
Jin Chu ◽  
...  

We report studies of the surface fringe structures and tunable bandgap width of atomic-thin boron nitride nanosheets (BNNSs). BNNSs are synthesized by using digitally controlled pulse deposition techniques. The nanoscale morphologies of BNNSs are characterized by using scanning electron microscope (SEM), and transmission electron microscopy (TEM). In general, the BNNSs appear microscopically flat in the case of low temperature synthesis, whereas at high temperature conditions, it yields various curved structures. Experimental data reveal the evolutions of fringe structures. Functionalization of the BNNSs is completed with hydrogen plasma beam source in order to efficiently control bandgap width. The characterizations are based on Raman scattering spectroscopy, X-ray diffraction (XRD), and FTIR transmittance spectra. Red shifts of spectral lines are clearly visible after the functionalization, indicating the bandgap width of the BNNSs has been changed. However, simple treatments with hydrogen gas do not affect the bandgap width of the BNNSs.


1976 ◽  
Vol 30 (1) ◽  
pp. 34-38 ◽  
Author(s):  
K. Visser ◽  
F. M. Hamm ◽  
P. B. Zeeman

Simultaneous relative radiances of the Hβ, Hγ, and Hδ spectral lines of hydrogen were measured sequentially at various lateral positions in an inductively coupled rf argon-hydrogen plasma operated at atmospheric pressure (12 kW, 9 MHz). Measurements to take self-absorption into account were also performed. By applying an Abel integral inversion, a radial radiance profile for each line was obtained. With the two-line temperature method, simultaneous temperature profiles were obtained from each of the three line-pairs. The difference between these three sets of values and the negative values obtained for the Hγ, Hδ pair indicates that thermal equilibrium does not exist in this plasma.


2013 ◽  
Vol 774-776 ◽  
pp. 471-478
Author(s):  
Song Bai Wang ◽  
Guang Jiu Lei ◽  
Ming Li ◽  
Li Ming Yu ◽  
Ying Nan Bu ◽  
...  

In high-power RF ion source, three different regions of the Hβand Hγintensities in the Balmer series of spectral lines for atomic hydrogen plasma were investigated. Three different regions of the Hβand Hγintensities were detected by the increase of input power (0-6 kW) at ICP. In hydrogen plasma spectrum, the Hβand Hγintensities showed three processes: slowly increase, quickly increase and stable saturation. The Stark effect in strong electrical field plays a crucial role in dominating the Balmer Hβand Hγemissions from high-density RF plasma.


2021 ◽  
Vol 5 (4) ◽  
pp. 198-210
Author(s):  
M. K. Dosbolayev ◽  
A. B. Tazhen ◽  
T. S. Ramazanov

This paper presents the experimental results on electron, ion temperatures and densities in a pulsed plasma accelerator. The values of electron densities and temperatures were computed using the methods of relative intensities of Hα and Hβ lines, Hβ Stark broadening, and the technique is based on Faraday cup beam current measurements. In this work, a linear optical spectrometer S-100 was used to acquire the emission spectra of hydrogen and air plasmas. In this spectrum, there are some lines due to Fe, Cu, N2, O2, and H2. The series of visible lines in the hydrogen atom spectrum are named the Balmer series. The spectral emissions of iron and copper occur throughout the gas breakdown and ignition of an arc discharge, during the erosion and sputtering of materials. The vacuum chamber and coaxial electrodes were made. The electron temperatures and densities in a pulsed plasma accelerator, measured via relative intensities of spectral lines and Stark broadening, at a charging voltage of a capacitor bank of 3 kV and a working gas pressure in a vacuum chamber of 40 mTorr, were 2.6 eV and 1.66 · 1016 cm−3 for hydrogen plasma. These results were compared with the Faraday cup beam current measurements. However, no match was found. Considering and analyzing this distinction, we concluded that the spectral method of plasma diagnostics provides more accurate results than electrical measurement. The theory of probe measurements can give approximate results in a moving plasma.


1977 ◽  
Vol 36 ◽  
pp. 191-215
Author(s):  
G.B. Rybicki

Observations of the shapes and intensities of spectral lines provide a bounty of information about the outer layers of the sun. In order to utilize this information, however, one is faced with a seemingly monumental task. The sun’s chromosphere and corona are extremely complex, and the underlying physical phenomena are far from being understood. Velocity fields, magnetic fields, Inhomogeneous structure, hydromagnetic phenomena – these are some of the complications that must be faced. Other uncertainties involve the atomic physics upon which all of the deductions depend.


Author(s):  
Martin Peckerar ◽  
Anastasios Tousimis

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.


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