scholarly journals New Data from Laser Interrogation of Electron-Atom Collisions Experiments

1996 ◽  
Vol 49 (2) ◽  
pp. 499
Author(s):  
AT Masters ◽  
RT Sang ◽  
WR MacGillivray ◽  
MC Standage
Keyword(s):  
Laser Radiation ◽  
Optical Pumping ◽  
Single Mode ◽  
Ground Level ◽  
Stokes Parameters ◽  
Scattered Electron ◽  
Electron Atom ◽  
Level Data ◽  
Superelastic Scattering ◽  
Upper Level

Recent data from two methods in which high resolution laser radiation is used to assist in determining electron-atom collision parameters are presented. The electron superelastic method has yielded the first measurement of Stokes parameters for electron de-excitation of the 32D5/2–32P3/2,1/2 transition of atomic Na, the upper level having been optically prepared by resonant, stepwise excitation from the 32S1/2 ground level via the 32P3/2 level using two single mode lasers. As well, we report on the development of a model to determine the optical pumping parameters for superelastic scattering from the 32P3/2 level when it is prepared by two lasers exciting from the F = 1 and F = 2 states respectively of the 32S1/ 2 ground level. Data are also presented for collision parameters for the excitation of the 61So–61 PI transition of the I = 0 isotope of Hg by electrons of 50 eV incident energy. The technique employed for these measurements is the stepwise electron–laser excitation coincidence method, in which the electron excited atom is further excited by resonant laser radiation, and fluorescence photons emitted by relaxation from the laser excited state are detected in coincidence with the scattered electron.

scholarly journals Инверсия вклада изотопа малой относительной концентрации в суммарный коэффициент поглощения смеси изотопов неона на переходе 3s-=SUB=-2-=/SUB=--2p-=SUB=-4-=/SUB=-

2019 ◽  
Vol 127 (8) ◽  
pp. 179
Author(s):  
Э.Г. Сапрыкин
Keyword(s):  
Numerical Modeling ◽  
Laser Radiation ◽  
Ground State ◽  
Optical Pumping ◽  
Discharge Plasma ◽  
Relative Concentration ◽  
Probe Laser ◽  
Decay Channels ◽  
Gas Discharge Plasma ◽  
Upper Level

AbstractAbsorption of probe laser radiation by a mixture of even isotopes of neon in a gas discharge plasma is investigated by the method of magnetic scanning of 3 s _2–2 p _4 transition. The contours of absorption lines of isotopes are resolved by means of numerical modeling. It is discovered that, upon decrease in relative concentration of one of the isotopes, its contribution to absorption is replaced by gain. The effect is found to be caused by radiative transfer of excitation energy between atoms of different kinds in the absence of a difference in level energies (the process known as optical pumping). The effect of this mechanism turned out to be substantial for the upper level transitions from which to the ground state are allowed while being absent for the lower level of the transition from which such transitions are forbidden although other decay channels are available.

Electron superelastic scattering from states of atomic sodium and rubidium

1996 ◽  
Vol 74 (11-12) ◽  
pp. 977-983 ◽  
Author(s):  
B. V. Hall ◽  
R. T. Sang ◽  
M. Shurgalin ◽  
W. R. MacGillivray ◽  
M. C. Standage ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Optical Pumping ◽  
Optical Excitation ◽  
Ground Level ◽  
Excitation Process ◽  
Atomic Sodium ◽  
Laser Modes ◽  
Superelastic Scattering ◽  
Nonzero Spin ◽  
Full Quantum

This paper reports on the extension of the electron superelastic scattering technique to three new situations. The first considers scattering from the 32P3/2 level of Na that has been excited by two laser modes tuned, respectively, to the transitions from the two hyperfine states of the 32S1/2 ground level. Both coherent and noncoherent modes are treated in a full quantum electrodynamic model of the laser excitation. Under certain conditions, the time-averaged probability of finding an atom in the 32P3/2 level exceeds 0.5. The second situation is electron superelastic scattering from the 32D5/2 level of Na that has been resonantly excited from the ground level via a resonant intermediate level. With the first observation of superelastically scattered electrons from this higher lying level recently recorded, this paper considers the extension of the quantum electrodynamics (QED) model to describe the optical excitation process. Application of superelastic scattering to the 52S1/2–52P3/2 transition of Rb is the third situation considered. The superelastic scattering formalism is extended to allow for a nonzero spin flip cross section for this transition. The resulting optical pumping terms are calculated using the QED model and the method of their determination for the superelastic scattering experiment described. The experimental design necessary to measure all of the collision parameters for this transition is discussed.

scholarly journals Wind Energy Meteorology: Insight into Wind Properties in the Turbine-Rotor Layer of the Atmosphere from High-Resolution Doppler Lidar

2013 ◽  
Vol 94 (6) ◽  
pp. 883-902 ◽  
Author(s):  
Robert M. Banta ◽  
Yelena L. Pichugina ◽  
Neil D. Kelley ◽  
R. Michael Hardesty ◽  
W. Alan Brewer
Keyword(s):  
Wind Energy ◽  
Ground Level ◽  
Turbine Rotor ◽  
Energy Industry ◽  
Doppler Lidar ◽  
Near Surface ◽  
Surface Measurements ◽  
Wind Measurements ◽  
Upper Level ◽  
Insight Into

Addressing the need for high-quality wind information aloft in the layer occupied by turbine rotors (~30–150 m above ground level) is one of many significant challenges facing the wind energy industry. Without wind measurements at heights within the rotor sweep of the turbines, characteristics of the flow in this layer are unknown for wind energy and modeling purposes. Since flow in this layer is often decoupled from the surface, near-surface measurements are prone to errant extrapolation to these heights, and the behavior of the near-surface winds may not reflect that of the upper-level flow.

Magnetic resonance of cesium atoms in the case of optical pumping by radiation from a single-mode injection laser

1983 ◽  
Vol 13 (3) ◽  
pp. 380-382 ◽  
Author(s):  
L S Kornienko ◽  
A L Kotkin ◽  
V I Malakhova ◽  
V V Maĭorshin ◽  
R M Umarkhodzhaev ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Optical Pumping ◽  
Single Mode ◽  
Injection Laser ◽  
Cesium Atoms

Complete experiments in electron–atom impact excitation: present status and future prospects

1996 ◽  
Vol 74 (11-12) ◽  
pp. 929-943
Author(s):  
Nils Andersen ◽  
Klaus Bartschat
Keyword(s):  
Review Paper ◽  
Stokes Parameters ◽  
Impact Excitation ◽  
Future Prospects ◽  
Electron Atom ◽  
Scattering Experiment ◽  
Spin Polarized ◽  
Common Framework ◽  
Theoretical Results ◽  
Present Understanding

An overview is given of the present understanding of excitation in electron–atom collisions, with particular emphasis on the extent to which a "perfect scattering experiment" in the Bederson sense has been achieved. Recent experimental and theoretical results are put into a common framework, generalizing the ideas and systematics, presented in a review paper, of the case of excitation by spin-polarized electron beams. For various levels of complexity, complete sets of coherence parameters are suggested, and their relationships to generalized Stokes parameters and generalized STU parameters are pointed out.

Direct excitation of potassium diffuse bands by single mode laser radiation

1986 ◽  
Vol 2 (3) ◽  
pp. 233-238 ◽  
Author(s):  
?. Vadla ◽  
K. Niemax ◽  
G. Pichler
Keyword(s):  
Laser Radiation ◽  
Single Mode ◽  
Mode Laser ◽  
Single Mode Laser ◽  
Direct Excitation

Mathematical Entities without Objects. On Realism in Mathematics and a Possible Mathematization of (Non)Platonism: Does Platonism Dissolve in Mathematics?

2020 ◽  
pp. 1-21
Author(s):  
Thierry Paul
Keyword(s):  
Dynamical Systems ◽  
Real World ◽  
Ground Level ◽  
Ground Floor ◽  
Mathematical Platonism ◽  
Levels Of Reality ◽  
Upper Level ◽  
The One

By looking at three significant examples in analysis, geometry and dynamical systems, I propose the possibility of having two levels of realism in mathematics: the upper one, the one of entities; and a subordinated ground one, the one of objects. The upper level (entities) is more the one of ‘operations’, of mathematics in action, of the dynamics of mathematics, whereas the ground floor (objects) is more dedicated to culturally well-defined objects inherited from our perception of the physical or real world. I will show that the upper level is wider than the ground level, therefore foregrounding the possibility of having in mathematics entities without underlying objects. In the three examples treated in this article, this splitting of levels of reality is created directly by the willingness to preserve different symmetries, which take the form of identities or equivalences. Finally, it is proposed that mathematical Platonism is – in fine – a true branch of mathematics in order for mathematicians to avoid the temptation of falling into the Platonist alternative ‘everything is real’/‘nothing is real’.

scholarly journals Improving and testing the empirical equatorial electrojet model with CHAMP satellite data

2004 ◽  
Vol 22 (9) ◽  
pp. 3323-3333 ◽  
Author(s):  
V. Doumouya ◽  
Y. Cohen
Keyword(s):  
Equatorial Electrojet ◽  
Ground Level ◽  
Longitudinal Variation ◽  
Equatorial Station ◽  
Champ Satellite ◽  
Magnetic Effects ◽  
Level Data ◽  
The Pacific ◽  
Magnetic Signatures ◽  
Data Points

Abstract. The longitudinal variation of the Equatorial Electrojet (EEJ) intensity has been revised including data from the equatorial station of Baclieu (Vietnam), where an unexpected enhancement of the EEJ magnetic effects is observed. The features of this longitudinal variation were also obtained with the CHAMP satellite, except in the Pacific and Atlantic Oceans, where no ground level data points were available.The EEJ magnetic signatures recorded on board the CHAMP satellite have been isolated for 325 passes in different longitude sectors around local noon. The results have been compared with the EEJ magnetic effects computed using the Empirical Equatorial Electrojet Model (3EM) proposed by Doumouya et al. (2003). The modeled EEJ magnetic effects are generally in good agreement with CHAMP observed EEJ magnetic signatures.

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