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Articles 1 - 11 of 11
Full-Text Articles in Physics
Transition Probabilities In Kr Ii And Kr Iii Spectra, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic
Transition Probabilities In Kr Ii And Kr Iii Spectra, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic
Articles
On the basis of the relative line intensity ratio (RLIR) method, transition probability values of the spontaneous emission (Einstein's A values) of 14 transitions in the singly (Kr II) and 7 transitions in doubly (Kr III) ionized krypton spectra have been obtained relatively to the reference A values related to the 435.548 nm Kr II and 324.569 nm Kr III, the most intensive transitions in the Kr II and Kr III spectra. Our Kr III transition probability values are the first data obtained experimentally using the RLIR method. A linear, low–pressure, pulsed arc operated in krypton discharge was used as …
Astrophysical Plasma Diagnostics Through Analysis Of Ar Iine Shape Characteristics, Vladimir Milosavljevic, Stevan Djenize
Astrophysical Plasma Diagnostics Through Analysis Of Ar Iine Shape Characteristics, Vladimir Milosavljevic, Stevan Djenize
Articles
On the basis of five accurately recorded neutral argon ( ) line shapes (in the 4s-5p transition) we have recovered the basic plasma parameters i.e. electron temperature ( T) and electron density ( N) using our new line deconvolution procedure in the case of three different plasmas created in a linear, low-pressure, pulsed arc discharge. The mentioned plasma parameters have also been measured using independent experimental diagnostic techniques. An excellent agreement has been found among the two sets of obtained parameters. This recommends our deconvolution procedure for plasma diagnostic purposes, especially in astrophysics where direct measurements of the …
Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic
Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic
Articles
On the basis of the precisely recorded 20 neutral krypton (Kr I) line shapes (in the 5s−5p and 5s−6p transitions), we have obtained the basic plasma parameters, i.e., electron temperature (T) and electron density (N) using our line deconvolution procedure in a plasma created in a linear, low-pressure, pulsed arc discharge operated in krypton. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends our deconvolution procedure for plasma diagnostical purposes, especially in astrophysics where direct measurements of the …
Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic
Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic
Articles
We do not agree with the authors of the preceding Comment [X. Nikolic, X. Ojurovic, and X. Mijatovic, Phys. Rev. E, 67, 058401, 2003]. Our numerical procedure for the deconvolution of the theoretical asymmetric convolution integral of a Gaussian and a plasma broadened spectral line profile jA,R(λ) for spectral lines enables the determination of all broadening parameters. All broadening parameters can be determined directly from the recorded line profile of a single line, with minimal assumptions or prior knowledge. Additional experimental diagnostics are not required.
Spacecraft Charging At Geosynchronous Altitudes: Current Balance And Critical Temperature In A Non-Maxwellian Plasma, Jose T. Harris
Spacecraft Charging At Geosynchronous Altitudes: Current Balance And Critical Temperature In A Non-Maxwellian Plasma, Jose T. Harris
Theses and Dissertations
Spacecraft charging threatens to disable spacecraft components and adversely impact any satellite function. Electrostatic charge, and especially discharge, can hinder the proper operation of, or destroy, spacecraft components, thereby rendering the spacecraft ineffective or inoperative. The level of charging is dependent on the particle energy (speed) distribution. Current spacecraft design and material provide limited protection against the dangers of electrostatic discharge, and active measures such as beam emission are also employed.
Single-Mode Raman Fiber Laser In A Multimode Fiber, Matthew B. Crookston
Single-Mode Raman Fiber Laser In A Multimode Fiber, Matthew B. Crookston
Theses and Dissertations
The feasibility of a transverse single-mode Raman fiber laser using a multimode fiber has been investigated. The Raman fiber laser operates in low-order transverse modes despite the fact the fiber supports multimode beam propagation. The performance characteristics of the Raman fiber laser are compared with those of the single-pass SRS beam.
Building Blocks For Time-Resolved Laser Emission In Mid-Infrared Quantum Well Lasers, Gabriel D. Mounce
Building Blocks For Time-Resolved Laser Emission In Mid-Infrared Quantum Well Lasers, Gabriel D. Mounce
Theses and Dissertations
The objective of this research is to improve the performance of mid-infrared semiconductor quantum-well lasers. Lasers operating in the mid-infrared are useful for many Air Force applications which include infrared (IR) countermeasures in particular. Countermeasure applications require lasers that are compact, and able to emit at high powers while operating at room temperature. Limits to power increases are seen in the transverse modal development of laser oscillation. These modes typically form in the waveguiding active region contributing to the laser output. However, competing modes outside of this region also develop when the confining structural layers have the right characteristics. These …
Optical Characterization Of Antimony-Based, Types-I And Ii, Multiple Quantum-Well Semiconductor Structures For Mid-Infrared Laser Applications, Edward G. Ferguson
Optical Characterization Of Antimony-Based, Types-I And Ii, Multiple Quantum-Well Semiconductor Structures For Mid-Infrared Laser Applications, Edward G. Ferguson
Theses and Dissertations
This experiment characterizes antimony-based, multiple quantum-well, types-I and -II, semiconductor samples designed for laser applications. The samples emit light in the 3-5-micron range to exploit an atmospheric transmission window, making them ideal for infrared (IR)-seeking missile countermeasures. Photoluminescence (PL) spectra were collected and yielded bandgap (E(sub g)) dependence-on-temperature relationships. The type-I sample was found to follow the Varshni equation, while the type-II samples showed a rise with temperature in a portion of the curve that should be linear according to the Varshni equation. The type-II samples followed the Varshni equation well at higher temperature. The PL study indicated that the …
An Optical Trap For Relativistic Plasma, Ping Zhang, Ned Saleh, Shouyuan Chen, Zhengming Sheng, Donald Umstadter
An Optical Trap For Relativistic Plasma, Ping Zhang, Ned Saleh, Shouyuan Chen, Zhengming Sheng, Donald Umstadter
Donald Umstadter Publications
The first optical trap capable of confining relativistic electrons, with kinetic energy <350 keV was created by the interference of spatially and temporally overlapping terawatt power, 400 fs duration laser pulses (<2.4x1018 W/cm2) in plasma. Analysis and computer simulation predicted that the plasma density was greatly modulated, reaching a peak density up to 10 times the background density (ne /n0;10) at the interference minima. Associated with this charge displacement, a direct-current electrostatic field of strength of ~2 x 1011 eV/m was excited. These predictions were confirmed experimentally by Thomson and Raman scattering diagnostics. Also confirmed were predictions that the electron density grating acted as a multi-layer mirror to transfer energy between the crossed laser beams, resulting …350>
Electron Bernstein Wave-X-O Mode Conversion And Electron Cyclotron Emission In Mast, Josef Preinhaelter, Pavol Pavlo, Vladimir Shevchenko, Martin Valovic, Linda L. Vahala, George Vahala
Electron Bernstein Wave-X-O Mode Conversion And Electron Cyclotron Emission In Mast, Josef Preinhaelter, Pavol Pavlo, Vladimir Shevchenko, Martin Valovic, Linda L. Vahala, George Vahala
Electrical & Computer Engineering Faculty Publications
Electron cyclotron emission (ECE) from overdense plasmas can only occur due to electron Bernstein waves (EBW) mode converting near the upper hybrid region to an electromagnetic wave. Experimental data of ECE observations on MAST are studied and compared with EBW-X-O mode conversion modeling results.
Magnetohydrodynamic Turbulence: The Development Of Lattice Boltzmann Methods For Dissipative Systems, Angus Ian Duncan Macnab
Magnetohydrodynamic Turbulence: The Development Of Lattice Boltzmann Methods For Dissipative Systems, Angus Ian Duncan Macnab
Dissertations, Theses, and Masters Projects
Computer simulations of complex phenomena have become an invaluable tool for scientists in all disciplines. These simulations serve as a tool both for theorists attempting to test the validity of new theories and for experimentalists wishing to obtain a framework for the design of new experiments. Lattice Boltzmann Methods (LBM) provide a kinetic simulation technique for solving systems governed by non-linear conservation equations. Direct LBMs use the linearized single time relaxation form of the Boltzmann equation to temporally evolve particle distribution functions on a discrete spatial lattice. We will begin with a development of LBMs from basic kinetic theory and …