Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Selected Works

2014

Discipline
Keyword
Publication
File Type

Articles 1 - 30 of 255

Full-Text Articles in Physics

Identification Of Hyperhalogens In Agn(Bo2)M (N = 1–3, M = 1–2) Clusters: Anion Photoelectron Spectroscopy And Density Functional Calculations, Xiang-Yu Kong, Hong-Guang Xu, Pratik Koirala, Wei-Jun Zheng, Anil K. Kandalam, Puru Jena Dec 2014

Identification Of Hyperhalogens In Agn(Bo2)M (N = 1–3, M = 1–2) Clusters: Anion Photoelectron Spectroscopy And Density Functional Calculations, Xiang-Yu Kong, Hong-Guang Xu, Pratik Koirala, Wei-Jun Zheng, Anil K. Kandalam, Puru Jena

Anil K. Kandalam

No abstract provided.


Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle Dec 2014

Hiv-1 Tat Membrane Interactions Probed Using X-Ray And Neutron Scattering, Cd Spectroscopy And Md Simulations., Kiyotaka Akabori, Kun Huang, Bradley Treece, Michael Jablin, Brian Maranville, Arthur Woll, John Nagle, Angel Garcia, Stephanie Tristram-Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

We report the effect on lipid bilayers of the Tat peptide Y47GRKKRRQRRR57 from the HIV-1 virus transactivator of translation (Tat) protein. Synergistic use of low-angle X-ray scattering (LAXS) and atomistic molecular dynamic simulations (MD) indicate Tat peptide binding to neutral dioleoylphosphocholine (DOPC) lipid headgroups. This binding induced the local lipid phosphate groups to move 3Å closer to the center of the bilayer. Many of the positively charged guanidinium components of the arginines were as close to the center of the bilayer as the locally thinned lipid phosphate groups. LAXS data for DOPC, DOPC/dioleoylphosphoethanolamine (DOPE), DOPC/dioleoylphosphoserine (DOPS), and a ...


What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori Dec 2014

What Are The True Values Of The Bending Modulus Of Simple Lipid Bilayers?, John Nagle, Michael Jablin, Stephanie Tristram-Nagle, Kiyotaka Akabori

Prof. Stephanie Tristram-Nagle Ph.D.

Values of the bending modulus KC are reviewed, and possible causes for the considerable differences are discussed. One possible cause is the use of glucose and sucrose in the classical micromechanical manipulation and shape analysis methods. New data, using the more recent low angle X-ray method, are presented that do not support an effect of glucose or sucrose on KC. Another possible cause is using an incomplete theory to interpret the data. Adding a tilt term to the theory clearly does not affect the value obtained from the shape analysis method. It is shown that a tilt term, using a ...


Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith Dec 2014

Suncircles: A Prose/Poem 12/18/2014, Charles Kay Smith

Charles Kay Smith

A current project is writing a book of poetry. The different kind of poetry I’m trying to write melds science, humanities, and aesthetic aims of clarity and a polished plain style with social consciousness. I’m uploading one of the poems in the collection as an example of the kind of poetry I’m trying to compose.


Active And Passive Imaging In The Thz Spectral Region: Phenomenology, Dynamic Range, Modes, And Illumination, Douglas T. Petkie, Corey Casto, Frank C. De Lucia, Steven R. Murrill, Brian Redman, Richard L. Espinola, Charmaine C. Franck, Eddie L. Jacobs, Steven T. Griffin, Carl E. Halford, Joe Reynolds, Sean O'Brien, David Tofsted Dec 2014

Active And Passive Imaging In The Thz Spectral Region: Phenomenology, Dynamic Range, Modes, And Illumination, Douglas T. Petkie, Corey Casto, Frank C. De Lucia, Steven R. Murrill, Brian Redman, Richard L. Espinola, Charmaine C. Franck, Eddie L. Jacobs, Steven T. Griffin, Carl E. Halford, Joe Reynolds, Sean O'Brien, David Tofsted

Douglas T. Petkie

The useful compromise between resolution and penetration power of the submillimeter or terahertz (THz) spectral region has long made it attractive for a variety of imaging applications. However, many of the demonstrations of imaging in this spectral region have used strategically oriented targets, especially favorable concealment materials, proximate imaging geometries, etc. This paper reports the results of studies aimed at better understanding the phenomenology of targets, the impact of this phenomenology on various active and passive imaging strategies, and most importantly, the development of imaging strategies that do not require the aforementioned special circumstances. Particular attention is paid to the ...


The Rotational Spectra Of The 61, 71, 81, 91 And 51/92 Vibrational States Of H15No3, Douglas T. Petkie, Mark Kipling, Ashley Jones, Paul Helminger, Ivan Medvedev, Atsuko Maeda, Markus Behnke, Brian J. Drouin, Charles E. Miller Dec 2014

The Rotational Spectra Of The 61, 71, 81, 91 And 51/92 Vibrational States Of H15No3, Douglas T. Petkie, Mark Kipling, Ashley Jones, Paul Helminger, Ivan Medvedev, Atsuko Maeda, Markus Behnke, Brian J. Drouin, Charles E. Miller

Douglas T. Petkie

The high-resolution rotational spectrum of H15NO3 has been recorded in the range between 74 and 850 GHz and used to complete an extensive analysis of the six vibrational states below 1000 cm−1 that include the isolated 81 and 91 states along with the weakly interacting 61 and 71 states and strongly interacting 51 and 92dyad. The 61 and 71 states couple via a weak Coriolis interaction while the 51 and 91 states couple through strong Fermi and weaker Coriolis interactions. The Hamiltonian models account for the observed torsional splitting in the 91 and 92 states of 2.4 and ...


Infrared Simulations Derived From Submillimeter Wave Analyses, Douglas T. Petkie, Rebecca A. H. Butler, Paul Helminger, Zbigniew Kisiel, Kenneth W. Jucks, Brenda P. Winnewisser, Manfred Winnewisser, Frank C. De Lucia Dec 2014

Infrared Simulations Derived From Submillimeter Wave Analyses, Douglas T. Petkie, Rebecca A. H. Butler, Paul Helminger, Zbigniew Kisiel, Kenneth W. Jucks, Brenda P. Winnewisser, Manfred Winnewisser, Frank C. De Lucia

Douglas T. Petkie

No abstract provided.


The Rotational Spectrum Of Chlorine Nitrate (Ciono2) In The Four Lowest Nv9 Polyads, Zbigniew Kisiel, Ewa Bialkowska Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Ivan Medvedev, Frank C. De Lucia Dec 2014

The Rotational Spectrum Of Chlorine Nitrate (Ciono2) In The Four Lowest Nv9 Polyads, Zbigniew Kisiel, Ewa Bialkowska Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Ivan Medvedev, Frank C. De Lucia

Douglas T. Petkie

The analysis of the recently recorded 78–378 GHz broadband spectrum of ClONO2 has been extended to cover rotational transitions in all 14 excited vibrational states up to 650 cm−1 above the ground state. We report new measurements and analysis of the 2ν9 and 3ν9 dyads, and first assignment and analysis for the 4ν9 and 5ν9 triads. The polyad fits encompass a total of over 20 000 newly measured transition frequencies and spectroscopic constants are reported for 10 vibrationally excited states in each of 35ClONO2 and37ClONO2. All polyads were fitted with a new coupling scheme between the perturbing states ...


Terahertz Imaging System Performance Model For Concealed-Weapon Identification, Steven R. Murrill, Eddie L. Jacobs, Steven K. Moyer, Carl E. Halford, Steven T. Griffin, Frank C. De Lucia, Douglas T. Petkie, Charmaine C. Franck Dec 2014

Terahertz Imaging System Performance Model For Concealed-Weapon Identification, Steven R. Murrill, Eddie L. Jacobs, Steven K. Moyer, Carl E. Halford, Steven T. Griffin, Frank C. De Lucia, Douglas T. Petkie, Charmaine C. Franck

Douglas T. Petkie

The U.S. Army Night Vision and Electronic Sensors Directorate (NVESD) and the U.S. Army Research Laboratory have developed a terahertz (THz) -band imaging system performance model for detection and identification of concealed weaponry. The MATLAB-based model accounts for the effects of all critical sensor and display components and for the effects of atmospheric attenuation, concealment material attenuation, and active illumination. The model is based on recent U.S. Army NVESD sensor performance modeling technology that couples system design parameters to observer–sensor field performance by using the acquire methodology for weapon identification performance predictions. This THz model has ...


A Fast Scan Submillimeter Spectroscopic Technique, Douglas T. Petkie, Thomas M. Goyette, Ryan P. A. Bettens, Sergei P. Belov, Sieghard Albert, Paul Helminger, Frank C. De Lucia Dec 2014

A Fast Scan Submillimeter Spectroscopic Technique, Douglas T. Petkie, Thomas M. Goyette, Ryan P. A. Bettens, Sergei P. Belov, Sieghard Albert, Paul Helminger, Frank C. De Lucia

Douglas T. Petkie

A new fast scan submillimeter spectroscopic technique (FASSST) has been developed which uses a voltage tunable backward wave oscillator (BWO) as a primary source of radiation, but which uses fast scan (~105 Doppler limited resolution elements/s) and optical calibration methods rather than the more traditional phase or frequency lock techniques. Among its attributes are (1) absolute frequency calibration to ~1/10 of a Doppler limited gaseous absorption linewidth (<0.1 MHz, 0.000 003 cm-1), (2) high sensitivity, and (3) the ability to measure many thousands of lines/s. Key elements which make this system possible include the excellent ...


A Mems Photoacoustic Detector Of Terahertz Radiation For Chemical Sensing, Nathan E. Glauvitz, S. Blazevic, Ronald A. Coutu Jr., Michael N. Kistler, Ivan Medvedev, Douglas T. Petkie Dec 2014

A Mems Photoacoustic Detector Of Terahertz Radiation For Chemical Sensing, Nathan E. Glauvitz, S. Blazevic, Ronald A. Coutu Jr., Michael N. Kistler, Ivan Medvedev, Douglas T. Petkie

Douglas T. Petkie

A piezoelectric Microelectromechanical system (MEMS) cantilever pressure sensor was designed, modeled, fabricated, and tested for sensing the photoacoustic response of gases to terahertz (THz) radiation. The sensing layers were comprised of three thin films; a lead zirconate titanate (PZT) piezoelectric layer sandwiched between two metal contact layers. The sensor materials were deposited on the silicon device layer of a silicon-on-insulator (SOI) wafer, which formed the physical structure of the cantilever. To release the cantilever, a hole was etched through the backside of the wafer and the buried oxide was removed with hydrofluoric acid. Devices were then tested in a custom ...


The Rotational Spectrum Of Chlorine Nitrate (Ciono2): V6 And The V5/V6V9 Dyad, Zbigniew Kisiel, Ewa Bialkowska-Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Frank C. De Lucia Dec 2014

The Rotational Spectrum Of Chlorine Nitrate (Ciono2): V6 And The V5/V6V9 Dyad, Zbigniew Kisiel, Ewa Bialkowska-Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Frank C. De Lucia

Douglas T. Petkie

No abstract provided.


A Comparative Analysis Of Numerical Approaches To The Mechanics Of Elastic Sheets, Michael Taylor, Benny Davidovitch, Zhanlong Qiu, Katia Bertoldi Nov 2014

A Comparative Analysis Of Numerical Approaches To The Mechanics Of Elastic Sheets, Michael Taylor, Benny Davidovitch, Zhanlong Qiu, Katia Bertoldi

Benny Davidovitch

No abstract provided.


Stilling Basin Performance Analysis By Adv, Seyed Sobhan Aleyasin, Nima Fathi, Peter Vorobieff Nov 2014

Stilling Basin Performance Analysis By Adv, Seyed Sobhan Aleyasin, Nima Fathi, Peter Vorobieff

Nima Fathi

The outlet flow from dams, channels, and pipes, as well as the river flow, can cause damage to the bed of the river or channel and cause scouring of structures such as the saddles of bridges, because of the huge amount of the kinetic energy carried by the flow. One of the ways to dissipate this energy is via the use of stilling basins, which are structures that calm the flow. Here we present a study of one type of stilling basins for pipe outlets based on a widely used standard1. During the study, splitters and cellular baffles were placed ...


A Sheet On Deformable Sphere: "Wrinklogami" Patterns Suppress Curvature-Induced Delamination, Evan Hohlfeld, Benny Davidovitch Nov 2014

A Sheet On Deformable Sphere: "Wrinklogami" Patterns Suppress Curvature-Induced Delamination, Evan Hohlfeld, Benny Davidovitch

Benny Davidovitch

No abstract provided.


Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen Nov 2014

Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen

David Kastor

We extend standard results for vacuum asymptotically locally AdS (AlAdS) spacetimes, showing that such spacetimes can be constructed as foliations where the induced metric on each hypersurface satisfies Einstein's equation with stress-energy. By an appropriate choice of stress-energy on the hypersurfaces, the resulting AlAdS spacetime satisfies Einstein's equation with a negative cosmological constant and physical stress tensor. We use this construction to obtain AlAdS solutions whose boundaries are FRW cosmologies sourced by a massless scalar field or by a perfect fluid obeying the strong energy condition. We focus on FRW universes that approach Minkowski spacetime at late times ...


Mesospheric Density Climatologies Determined At Midlatitudes Using Rayleigh Lidar, David L. Barton, Vincent B. Wickwar, Leda Sox, Joshua P. Herron Nov 2014

Mesospheric Density Climatologies Determined At Midlatitudes Using Rayleigh Lidar, David L. Barton, Vincent B. Wickwar, Leda Sox, Joshua P. Herron

Leda Sox

The original Rayleigh-scatter lidar that operated at the Atmospheric Lidar Observatory (ALO; 41.7°N, 111.8°W) in the Center for Atmospheric and Space Sciences (CASS) on the campus of Utah State University (USU), collected 11 years of data between 1993 and 2004. From Rayleigh lidar photon-count returns, relative densities throughout the mesosphere, from 45 to 90 km, were determined. Using these relative densities, three climatologies are derived, each using a different density normalization method at 45 km: the first method normalized the relative densities to a constant; the second normalized them to the NRLMSISe00 empirical model; and the ...


Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson Nov 2014

Kinetic Competition During The Transcription Cycle Results In Stochastic Rna Processing, Antoine Coulon, Matthew L. Ferguson, Valeria De Turris, Murali Palangat, Carson C. Chow, Daniel R. Larson

Matthew L. Ferguson

Synthesis of mRNA in eukaryotes involves the coordinated action of many enzymatic processes, including initiation, elongation, splicing, and cleavage. Kinetic competition between these processes has been proposed to determine RNA fate, yet such coupling has never been observed in vivo on single transcripts. In this study, we use dual-color single-molecule RNA imaging in living human cells to construct a complete kinetic profile of transcription and splicing of the β-globin gene. We find that kinetic competition results in multiple competing pathways for pre-mRNA splicing. Splicing of the terminal intron occurs stochastically both before and after transcript release, indicating there is not ...


Paul Ion Trap As A Diagnostic For Plasma Focus, S.M. Kiai, .. ., Ahmad Talaei, Et Al. Nov 2014

Paul Ion Trap As A Diagnostic For Plasma Focus, S.M. Kiai, .. ., Ahmad Talaei, Et Al.

Ahmad Talaei

The plasma discharge contamination by high and low Z Impurities affect the rate of nuclear fusion reaction products, specially when light particles have to be confined. These impurities should be analyzed and can be fairly controlled. This paper reports on the development of a Paul ion trap with ion sources by impact electron ionization as a diagnostic for the 10 kJ Iranian sunshine plasma focus device. Preliminary results of the residual gas are analyzed and presented.


Preliminary Results Of Is Plasma Focus As A Breeder Of Short-Lived Radioisotopes 12c(D,N)13n, S.M. Kiai, . ., Ahmad Talaei, Et Al. Nov 2014

Preliminary Results Of Is Plasma Focus As A Breeder Of Short-Lived Radioisotopes 12c(D,N)13n, S.M. Kiai, . ., Ahmad Talaei, Et Al.

Ahmad Talaei

Modified IS (Iranian Sun) plasma focus (10 kJ,15 kV, 94 μF, 0.1 Hz) has been used to produce the short-lived radioisotope 13N (half-life of 9.97 min) through 12C(d,n)13N nuclear reaction. The filling gas was 1.5–3 torr of hydrogen (60%) deuterium (40%) mixture. The target was solid nuclear grade graphite with 5 mm thick, 9 cm width and 13 in length. The activations of the exogenous target on average of 20 shots (only one-third acceptable) through 10–13 kV produced the 511 keV gamma rays. Another peak found at the 570 keV gamma ...


Kinematic Effects In Large Transport Aircraft, Shem Malmquist, Dennis Vincenzi, Dahai Liu Nov 2014

Kinematic Effects In Large Transport Aircraft, Shem Malmquist, Dennis Vincenzi, Dahai Liu

Dahai Liu

The control of an aircraft relies on sensory feedback. It follows that any aspect that could create a situation where that feedback is faulty can lead to unintended outcomes. The size of very large jet aircraft can result in kinematic effects that impact the perceptions of the flight crew. Due to the large amount of inertia involved, coupled with aerodynamic factors, when the aircraft pitch (θ) is initially changed, the short term actual motion of the aircraft, as viewed from the center of gravity, remains relatively unchanged. As a consequence of aircraft design, this results in the flight deck changing ...


Weak Decays Of Λ4He, J. D. Parker, M. J. Athanas, P. D. Barnes, G. Diebold, Gregg Franklin, Brian Quinn, F. Rozon, Reinhard A. Schumacher, I. Sukaton, V. J. Zeps Nov 2014

Weak Decays Of Λ4He, J. D. Parker, M. J. Athanas, P. D. Barnes, G. Diebold, Gregg Franklin, Brian Quinn, F. Rozon, Reinhard A. Schumacher, I. Sukaton, V. J. Zeps

Reinhard A Schumacher

We measured the lifetime and the mesonic and nonmesonic decay rates of the Λ4He hypernucleus. The hypernuclei were created using a 750 MeV/c momentum K- beam on a liquid 4He target by the reaction 4He (K-,π-)Λ4He. The Λ4He lifetime was directly measured using protons from Λp→np nonmesonic decay (also referred to as proton-stimulated decay) and was found to have a value of τ=245±24 ps. The mesonic decay rates were determined from the observed numbers of π-'s and π○'s as Γπ-/Γtot=0.270±0.024 and Γπ○/Γtot=0.564±0.036 ...


Plasma Focus Device As A Breeder Of 14.66 Mev Protons To Produce Short-Lived Radioisotopes, A. Zaeem, S.M. Kaia, M. Sedaghatizadeh, Ahmad Talaei Oct 2014

Plasma Focus Device As A Breeder Of 14.66 Mev Protons To Produce Short-Lived Radioisotopes, A. Zaeem, S.M. Kaia, M. Sedaghatizadeh, Ahmad Talaei

Ahmad Talaei

In plasma focus devices filled deuterium gas with low pressure admixture gas, 3He, the deuterium creates high energy protons of 14.66 MeV through the 3He(d, p) 4He(Q = 18.35 MeV) fusion reaction. This reaction takes place due to the thermal and non-thermal (beam-target) mechanisms. The proton yield production for deuterium filling gas is determined by using the beam-target character of the pinched plasma and moving boiler model. If we use a low pressure admixture gas like 11B, these high energy protons in turn, could generate short-lived radioisotopes like 11C (used in positron emission tomography) via the 11B ...


Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia Oct 2014

Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

In this article, considering the most important interactions between the ionized admixture particles and the working plasma ones, we have analyzed the effect of added gas on the current and confinement time of the pinched plasma in plasma focus devices. Moreover, we demonstrate how heating and cooling the pinched plasma can be controlled by the increase and decrease on the percentage of the added particles and by this way the rise in the rate of D–D nuclear reactions is calculated.


Theoretical Study Of The Endogenous Production Of N-13 In 115 Kj Plasma Focus Device Using Methane Gas, Saeedeh Haghani, A. Sadighzadeh, Ahmad Talaei, A. Zeem, S.M. Kiai, A. Heydarnia, V. Damideh Oct 2014

Theoretical Study Of The Endogenous Production Of N-13 In 115 Kj Plasma Focus Device Using Methane Gas, Saeedeh Haghani, A. Sadighzadeh, Ahmad Talaei, A. Zeem, S.M. Kiai, A. Heydarnia, V. Damideh

Ahmad Talaei

Mather type plasma focus device with the bank energy of 115 kJ (40 kV, 144μF) was studied for induced activity of N-13; a short-lived radioisotope β+ emitter with 511 keV of gamma rays and has a half-life of t1/2 = 9.93 min through 12C (d, n)13N nuclear reaction. N-13 radioisotope is used in Positron Emission Tomography (PET) for imaging and treatment. In this paper endogenous production of 13N is considered. It is shown by adding 3–4 % CH4 to the chamber, the induced activity of N-13 has increased about 4 %. Our study is representative of producing 106 − 109 ...


Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al. Oct 2014

Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al.

Ahmad Talaei

The output characteristics of a Filippove-Type plasma focus “Dena” (288 μF, 25 kV, 90 kJ) is numerically investigated by considering the voltage, current, current derivative, and maximum current as a function of capacitor bank energy in the constant Argon gas pressure and compared to the experiment. It is shown that increase on the bank energy leads to the increment on the maximum current and decrement on the pinch time.


Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem Oct 2014

Effects Of Admixture Gas On The Production Of 18f Radioisotope In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia, A. Zeem

Ahmad Talaei

In this article, the effect of admixture gas on the heating and cooling of pinched plasma directly related to the enhancement or reduction of 18F production through the 16O(3He, p)18F is considered in the plasma focus devices. It is shown that by controlling the velocity of added Oxygen particles mixed with the working helium gas into the plasma focus chamber, one can increase the current and decrease the confinement time (plasma heating) or vice verse (plasma cooling). The highest level of nuclear activities of 18F was found around 16% of the Oxygen admixture ...


Study The Influence Of The Bank Energy On The Dynamical Pinch In Plasma Focus, Ahmad Talaei, S.M. Kaia Oct 2014

Study The Influence Of The Bank Energy On The Dynamical Pinch In Plasma Focus, Ahmad Talaei, S.M. Kaia

Ahmad Talaei

The plasma focus discharge can generate, accelerate and pinch the plasma up to high density and temperature in a pulsed mode manner. Applications aspects of discharge require high efficiency of the fusion products. This situation acquires optimized operational parameters for the proper discharge. In this article, we have studied the plasma parameters and neutron performance dependency on bank energy. First, analytical expressions are derived from the equation of motion for the plasma particles in the radial phase. Then, the related fusion neutrons, both thermal and non-thermal, together with the discharge anisotropy in the low pressure regimes for the ‘Dena’ plasma ...


Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar Oct 2014

Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar

Ahmad Talaei

A characteristic feature of physical processes occurring in pinched plasma is their tendency to generate thermal and nonthermal emissions. In this case, the roles played by plasma compression dynamics such as pinch formation, pinch disruption, expansion, etc., are predominant. In this paper, first, we present some of the experimental results concerning the thermal and nonthermal neutron emissions. Then, a new approach based on some theoretical assumptions and the experimental data for which the pinched plasma density evolution was studied are introduced. In the new approach, the compression dynamics are divided into two phases: plasma compression (thermal) and plasma expansion (nonthermal ...


Development Of Practical Method Using A Monte Carlo Code For Evaluation Of Optimum Fuel Pitch In A Typical Vver-1000 Core, Navid Taheranpoura, Ahmad Talaei Oct 2014

Development Of Practical Method Using A Monte Carlo Code For Evaluation Of Optimum Fuel Pitch In A Typical Vver-1000 Core, Navid Taheranpoura, Ahmad Talaei

Ahmad Talaei

In this work, we developed a practical method to evaluate the optimum moderator-to-fuel ratio of a typical VVER reactor using a Monte Carlo code. To reach this aim, by analyzing the curves of the infinite multiplication factor (k) versus moderator-to-fuel ratio, the optimum fuel pitch is determined for different fuel diameters of the proposed fuel elements using the MCNPX code. Optimum moderator-to-fuel ratio and fuel pitch were determined from the curves where the value of k is maximum for cold conditions and is located in an under-moderated region for hot conditions. Also, the void reactivity coefficient must be negative and ...