Ivanov V.V.,University of Nevada, Reno |
Altemara S.D.,University of Nevada, Reno |
Astanovitskiy A.A.,University of Nevada, Reno |
Sarkisov G.S.,Ktech Corporation |
And 3 more authors.
IEEE Transactions on Plasma Science | Year: 2010
Laser probing diagnostics at the wavelength of 266 nm were developed for investigation of the 1-MA z-pinch plasmas. The absorption and refraction in plasma are significantly smaller at 266 nm than at the regular wavelength of 532 nm. These features allow observation of fine details in the z-pinch plasma at the ablation, implosion, and stagnation phases. Two-color shadowgraphy at 532/266 nm presents a structure of ablating wires and implosion bubbles in wire arrays. Plasma distribution and dynamics in compact cylindrical, star, and planar wire arrays can be studied at the wavelength of 266 nm. An electron density Ne > 5 • 1019 cm-3 was reconstructed with interferometry at 266 nm in the stagnated z-pinch. Further development of laser probing diagnostics of the z-pinch plasmas is discussed. © 2010 IEEE.
Lerner E.J.,Lawrenceville Plasma Physics Inc. |
Falomo R.,National institute for astrophysics |
Scarpa R.,Institute of Astrophysics of Canarias
International Journal of Modern Physics D | Year: 2014
The Tolman test for surface brightness (SB) dimming was originally proposed as a test for the expansion of the universe. The test, which is independent of the details of the assumed cosmology, is based on comparisons of the SB of identical objects at different cosmological distances. Claims have been made that the Tolman test provides compelling evidence against a static model for the universe. In this paper we reconsider this subject by adopting a static Euclidean universe (SEU) with a linear Hubble relation at all z (which is not the standard Einstein-de Sitter model), resulting in a relation between flux and luminosity that is virtually indistinguishable from the one used for ΛCDM models. Based on the analysis of the UV SB of luminous disk galaxies from HUDF and GALEX datasets, reaching from the local universe to z ∼ 5, we show that the SB remains constant as expected in a static universe. A re-analysis of previously published data used for the Tolman test at lower redshift, when treated within the same framework, confirms the results of the present analysis by extending our claim to elliptical galaxies. We conclude that available observations of galactic SB are consistent with a SEU model. We do not claim that the consistency of the adopted model with SB data is sufficient by itself to confirm what would be a radical transformation in our understanding of the cosmos. However, we believe this result is more than sufficient reason to examine this combination of hypotheses further. © 2014 World Scientific Publishing Company.
Murali S.K.,Lawrenceville Plasma Physics Inc. |
Emmert G.A.,University of Wisconsin - Madison |
Santarius J.F.,University of Wisconsin - Madison |
Kulcinski G.L.,University of Wisconsin - Madison
Physics of Plasmas | Year: 2010
Inertial electrostatic confinement fusion devices are compact sources of neutrons, protons, electrons, and x rays. Such sources have many applications. Improving the efficiency of the device also increases the applications of this device. Hence a thorough understanding of the operation of this device is needed. In this paper, we study the effect of chamber pressure on the temperature of the cathode. Experimentally, the grid temperature decreases as the chamber pressure increases; numerical simulations suggest that this is caused by the reduction of the hot ion current to the cathode as the pressure increases for constant power supply current. Such an understanding further supports the conclusion that the asymmetric heating of the cathode can be decreased by homogenizing the ion flow around the cathode. © 2010 American Institute of Physics.
Krupakar Murali S.,Lawrenceville Plasma Physics Inc. |
Blake A.M.,Lawrenceville Plasma Physics Inc. |
Haboub A.,Lawrenceville Plasma Physics Inc.
Journal of Fusion Energy | Year: 2011
To gain insight into the synchronization, simultaneity, and switching behavior of the individual switch, two TIA-525 Optical/Electrical converters have been recently introduced to DPF experiments at Lawrenceville Plasma Physics (LPP). These electronic devices, attached to two spark gap switches through optical fibers, detect light sampled from the switch firing and convert it to amplified voltage signals. We observed that in terms of simultaneity and synchronization, the firing behavior and quality of the pair of switches monitored are not the same. Some switches, among the twelve that are being used, fired at the trigger voltage within few tens of ns while the others fired much later (after ~1-2 μs) and are triggered at or after the pinch voltage rise. The results from the present work show evidence of pinch voltage triggering the switches. Since the pinch voltage is over three times the voltage of the capacitors, this voltage triggers those capacitors that do not fire during the regular high voltage trigger pulse. This, we suggest, could affect the efficiency of the device as it simply drains the reserved energy in the system. We present results of an empirical study of spark gap switch firing as well as the total current that is followed using the Rogowski coil. © 2011 Springer Science+Business Media, LLC.