Experimental Study of Ion Dynamic Effects in Overlapping Helium Lines at Low Densities

1983 ◽  
Vol 38 (1) ◽  
pp. 37-46 ◽  
Author(s):  
A. Piel ◽  
H. Richter
Keyword(s):  
Experimental Study ◽  
High Purity ◽  
Line Shape ◽  
Plasma Source ◽  
Line Profiles ◽  
Dynamic Effects ◽  
Electron Densities ◽  
Plasma Parameters ◽  
Critical Comparison

Abstract The line profiles of the overlapping helium lines 447.1 nm and 492.2 nm have been investigated in an improved plasma source of high purity at electron densities of 1 × 1021 m−3 and 3 × 1021 m−3 . The plasma parameters Ne, Te and T0 were determined carefully by independent diagnostics, which enables a critical comparison with existing theories (BCS II and MMM). We observed ion dynamic effects which considerably modify the line shape of the forbidden components. Our experiments extend the existing observations towards higher ion temperatures. Systematic trends observed earlier are critically discussed.

Experimental Study of the Stark Broadened Helium Ion Lines Hell 121.5, 164.0 and 468.6 nm

1984 ◽  
Vol 39 (11) ◽  
pp. 1041-1048 ◽  
Author(s):  
A. Piel ◽  
J. Slupek
Keyword(s):  
Experimental Study ◽  
Fine Structure ◽  
High Purity ◽  
Laser Interferometer ◽  
Plasma Parameters ◽  
Line Shapes ◽  
Helium Ion ◽  
Balmer Lines ◽  
Theoretical Line ◽  
Coupled Cavity

Using a pulsed linear discharge of high purity, Stark broadened profiles of the first two Balmer lines and the Paschen-α line of HeII have been investigated. The electron density (Ne = 5.5 · 1022 m-3) was measured with a coupled cavity He-Ne laser interferometer. The intensity ratio of the HeII 468.6 nm and the HeI 471.3 nm line was employed to determine the electron temperature (Te = 3.8 eV). At these plasma parameters the measured ion lines are unaffected by self absorption. This enables direct comparison with existing theories. Discrepancies between experimental and theoretical line shapes are critically discussed. Fine structure effects, usually neglected in theories, turn out to be important for the Balmer-α line.

scholarly journals Broadening of the Neutral Helium 492 nm Line in a Corona Discharge: Code Comparisons and Data Fitting

2018 ◽  
Author(s):  
Roshin Raj Sheeba ◽  
Mohammed Koubiti ◽  
Nelly Bonifaci ◽  
Franck Gilleron ◽  
Jean-Christophe Pain ◽  
...  
Keyword(s):  
Emission Line ◽  
Corona Discharge ◽  
Line Shape ◽  
Diagnostic Technique ◽  
Parameter Determination ◽  
Line Profiles ◽  
Plasma Parameters ◽  
Line Shapes ◽  
Physical Effects

Passive plasma spectroscopy is a well-established non-intrusive diagnostic technique. Depending on the emitter and its environment which determine the dominant interactions and effects governing emission line shapes, passive spectroscopy allows the determination of electron densities, emitter and perturber temperatures as well as other quantities like abundances. However, using spectroscopy needs appropriate line shape codes retaining all the physical effects governing the emission line profiles. This requires for line shape code developers to continuously correct or improve them to increase their accuracy when applied for diagnostics. This is exactly the aim expected from code-code and code-data comparisons. In this context, the He I 492 nm emitted in a helium corona discharge at room temperature represents an ideal case since its profile results from several broadening mechanisms: Stark, Doppler, resonance and van der Waals. The importance of each broadening mechanism depends on the plasma parameters. Here the profiles of the He I 492 nm in a helium plasma computed by various codes are compared for a selected set of plasma parameters. In addition, preliminary results related to plasma parameter determination using experimental spectra from a helium corona discharge at low pressure 1- 2 bars, are presented.

Long-pulse plasma source for SMOLA helical mirror

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Ivan A. Ivanov ◽  
V. O. Ustyuzhanin ◽  
A. V. Sudnikov ◽  
A. Inzhevatkina
Keyword(s):  
Magnetic Field ◽  
Gas Flow ◽  
Supply Voltage ◽  
Hydrogen Plasma ◽  
Plasma Source ◽  
Lanthanum Hexaboride ◽  
Plasma Stream ◽  
Plasma Parameters ◽  
Plasma Properties ◽  
Plasma Gun

A plasma gun for forming a plasma stream in the open magnetic mirror trap with additional helicoidal field SMOLA is described. The plasma gun is an axisymmetric system with a planar circular hot cathode based on lanthanum hexaboride and a hollow copper anode. The two planar coils are located around the plasma source and create a magnetic field of up to 200 mT. The magnetic field forms the magnetron configuration of the discharge and provides a radial electric insulation. The source typically operates with a discharge current of up to 350 A in hydrogen. Plasma parameters in the SMOLA device are Ti ~ 5 eV, Te ~ 5–40 eV and ni ~ (0.1–1)  × 1019 m−3. Helium plasma can also be created. The plasma properties depend on the whole group of initial technical parameters: the cathode temperature, the feeding gas flow, the anode-cathode supply voltage and the magnitude of the cathode magnetic insulation.

The experimental study of plasma parameters in MAGO chamber

2002 ◽  
Author(s):  
V.K. Chernyshev ◽  
A.N. Demin ◽  
Yu.N. Dolin ◽  
V.I. Dudin ◽  
V.P. Korchagin ◽  
...  
Keyword(s):  
Experimental Study ◽  
Plasma Parameters

scholarly journals Zodiacal Light - Scattered Fraunhofer Line Profiles

1996 ◽  
Vol 150 ◽  
pp. 337-340
Author(s):  
David Clarke
Keyword(s):  
Line Shape ◽  
Brightness Variation ◽  
Line Profiles ◽  
Scattering Function ◽  
Zodiacal Light ◽  
Successful Model ◽  
Fraunhofer Line ◽  
Shape Changes

AbstractThe scattering function of Hong's successful model for the brightness variation with elongation, B(ε), of the Zodiacal Light has been used to calculate profiles of Doppler shifted Fraunhofer lines. Substantial line shape changes with ε are predicted with an indication of a bifurcation at ε < 30°, so offering an explanation for reported F corona observations.

Experimental study of a radial plasma source

2009 ◽  
Vol 16 (4) ◽  
pp. 043507 ◽  
Author(s):  
G. Makrinich ◽  
A. Fruchtman
Keyword(s):  
Experimental Study ◽  
Plasma Source

The impact theory of spectral line shapes: a paradigm shift

2013 ◽  
Vol 91 (11) ◽  
pp. 879-895 ◽  
Author(s):  
A.D. May ◽  
W.-K. Liu ◽  
F.R.W. McCourt ◽  
R. Ciuryło ◽  
J. Sanchez-Fortún Stoker ◽  
...  
Keyword(s):  
Spectral Line ◽  
Line Shape ◽  
Paradigm Shift ◽  
Wigner Distribution ◽  
Kinetic Equations ◽  
Line Profiles ◽  
Line Shapes ◽  
Experimental Line ◽  
Impact Theory ◽  
The Impact

An overview of the binary collision impact theory of spectral line shapes has been given to provide a unified statistical mechanical approach to line-shape theory, laser theory, nonlinear optics, and transport phenomena in dilute gases. The computation of spectral line profiles corresponding to those obtained from ultra-high-resolution spectral line-shape measurements requires numerical ab initio calculation of scattering amplitudes directly from the underlying dynamics of collisions between radiatively active molecules and their perturbers. The Wigner distribution function–density matrix is utilized to describe the kinetic theory of spectral line shapes and to discuss the various collisional processes that contribute to the kernel of kinetic equations. The influence of features of the potential energy surface on spectral parameters is also discussed, and the importance of comparing experimental line profiles directly with numerically computed line shapes obtained from reliable interaction potentials is emphasized. This contrasts sharply with the universal practice of comparing experimental line widths and shifts using some average or approximate theoretical scattering cross-sections and it contrasts sharply with fitting experimental profiles to some convenient analytical line-shape model; hence the phrase “a paradigm shift” in the title of this work.

Sign in / Sign up

Export Citation Format

Share Document