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Articles 1 - 8 of 8
Full-Text Articles in Physics
Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran
Abrupt Change In Neon Discharge Plasma Detected Through Optogalvanic Effects, Xianming Han, Michael Blosser, Prabhakar Misra, Haridass Chandran
Xianming Han
When a laser is tuned between two excited energy levels of a gas in a Direct Current discharge lamp, the discharge current will experience a temporary disturbance lasting tens or hundreds of microseconds known as the optogalvanic effect. We have carried out extensive studies of optogalvanic effects in neon discharge plasmas for transitions at 621.7 nm, 630.5 nm, 638.3 nm, 650.7 nm and 659.9 nm. A nonlinear least-squares Monte Carlo technique has been used to determine the relevant amplitude coefficients, decay rates and the instrumental time constant. We discovered an abrupt change in the neon discharge plasma at a discharge …
Collisional Ionization Of Excited State Neon In A Gas Discharge Plasma, Xianming Han, Verl Wiseheart, Scott Conner, Meng-Chih Su, David Monts
Collisional Ionization Of Excited State Neon In A Gas Discharge Plasma, Xianming Han, Verl Wiseheart, Scott Conner, Meng-Chih Su, David Monts
Xianming Han
We report the first case where it is possible to clearly identify and quantitatively characterize the dominant physical processes contributing to production of the optogalvanic effect (OGE) signal in a discharge plasma. This work concentrates on the simplest case where only two states are involved in the optical transition. The theoretical model with only four parameters is in excellent agreement with the experimentally obtained time-resolved OGE waveforms. The collisional ionization rate in the upper state is twice as fast as that in the lower state although the two states are only separated by 1.94 eV. We conclude that the optogalvanic …
Influence Of Admixture Gas On The Enhancement Of Neutron Production In Plasma Focus Devices, Ahmad Talaei, S.M. Kaia
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.
Study The Output Characteristics Of A 90 Kj Filippove-Type Plasma Focus, S.M. Kiai, Ahmad Talaei, Et Al.
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
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 …
Pinched Plasma Study In A Filippov-Type Plasma Focus “Dena”, Ahmad Talaei, S. Kaia, S. Adlparvar
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). …
Scientists At Cern Are Wrong About Faster Than Light Particles, Or They Are Being Misrepresented, Hontas Farmer
Scientists At Cern Are Wrong About Faster Than Light Particles, Or They Are Being Misrepresented, Hontas Farmer
Hontas F Farmer
The postulate of special relativity, which in common terms means that no particle can travel faster than the speed of light, has been tested and shown to be correct in literally billions of measurements. So the scientists at CERN who report measuring neutrino's moving faster than light are either WRONG or are being grossly misrepresented in many media outlets. Every other time a packet of particles collided with another packet of particles special relativity has been borne out. The experiment reported in many outlets, conducted at CERN, has been reported as "showing Einstein was wrong". I don't think so.
Simulation Of Ultrashort Laser Pulse Propagation And Plasma Generation In Nonlinear Media. Dissertation, Jeremy Gulley
Simulation Of Ultrashort Laser Pulse Propagation And Plasma Generation In Nonlinear Media. Dissertation, Jeremy Gulley
Jeremy R. Gulley
In this dissertation, a modified nonlinear Schrödinger equation is derived, which describes the propagation of ultrashort laser pulses through nonlinear materials in which plasma generation and laser-induced damage can occur. Differences between this model and models currently used in the literature are investigated and analyzed by numerical simulations. Ultrafast laser-induced material modification is investigated using this method by simulating the propagation of fully 3+1D (3 spatial plus 1 time dimension) laser pulses, which are numerically constructed from experimentally measured beam profiles and pulse shape data. The latest of these investigations reveals that standard rate-equation models for the free-electron plasma generation …