Speed of light demonstration using Doppler beat

From an apparatus previously designed for measuring the Doppler shift using a rotating mirror, an improved, versatile version was developed for speed of light demonstrations in a classroom or a teaching laboratory. By adding a second detector and adequate beam-splitter and mirrors, three different configurations are easily assembled. One configuration is used for time-of-flight measurements between a near and a far detector, allowing one to measure the speed of light provided that the path length between detectors is known. Another variation is the interferometric method obtained by superposing the far and near signals in such a way that a minimum of the combined signal is obtained when the time delay makes the signals arrive out of phase by π radians. Finally, the standard Doppler configuration allows the measurement of the frequency beat as a function of the rotation frequency. The main advantages of the apparatus are (a) the experimental setup is simple and completely accessible to undergraduate students, (b) the light is visible, students can see the rays, which, with the use of appropriate screens, can be blocked at any point along their paths, (c) the experiment can take place entirely within the teaching laboratory or demonstration room (using the interferometric method, the shortest distance to the far mirror was as small as 0.5 m), and (d) different configurations can be built, including some economical setups within the budget of teaching laboratories.Fil: Bernal, Luis. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

First experimental values for the light penetration depth of platinum and iron gases at 532 nm

Light penetration depth is a fundamental property that has been researched extensively with a large amount of materials. Among those studies, different planetary atmospheres and material phases, like plasmas, had been previously addressed, both theoretically and experimentally. However, no experimental data are available for platinum and iron gases due to the difficulties for the creation of gas state from a solid metal material. This work present experimental penetration depths at 532 nm laser light for iron and platinum gases produced by a carefully tuned exploding wire system in atmospheric air. Iron presents a larger dispersion on the data than platinum, which is explained because of its large magnetic permeability value, that generates a less homogeneous gas than in the platinum case.Fil: Prieto, Gonzalo Rodríguez. Universidad de Castilla-La Mancha; EspañaFil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

Experimental determination of the resistivity limits for platinum and iron metal gases using an exploding wire

Transport properties of metals in solid, liquid, gas or plasma phases are an open area of research, both theoretically and experimentally. Concretely, there are no measurements available for the resistivity of gas phase of metals. In the latter case, the use of exploding wire systems allows one to reach states from solid to plasma that are not accessible with other experimental methods. In this work, following a measurement method previously used with copper, experimental resistivity limits of iron and platinum metal gases are presented based on measurements performed on the metal gas expansion phase.Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Rodríguez Prieto, Gonzalo. Universidad de Castilla-La Mancha; Españ

Obtención de espectros usando un smartphone en la clase de Física

Este artículo presenta los fundamentos para convertir un teléfono inteligente (o smartphone) en un espectrómetro casero. Utilizando un Compact Disc Digital Audio y una ranura ubicada adecuadamente se puede observar, entre otros, el espectro de emisión de una lámpara fluorescente compacta. Además, en este trabajo se incluyen los pasos metodológicos para medir las líneas de Fraunhofer del Sol de mayor ancho espectral. La propuesta está pensada para llevar adelante una clase práctica de espectros lumínicos tanto en instituciones de educación media como así también en cursos introductorios de física universitaria.This article presents the basics for converting a smartphone as a home spectrometer. Using a Compact Disc Digital Audio and a properly located slot, the emission spectrum of a compact fluorescent lamp and other sources can be observed. This work includes the methodological steps to measure the Fraunhofer's lines of the sun with the greatest spectral width. The proposal is designed to carry out a practical class of light spectra both from institutions of secondary education as well as in introductory courses in university physics.Fil: Szigety, Esteban Guillermo. Universidad Nacional de Mar del Plata; ArgentinaFil: Bernal, Luis Jaime. Universidad Nacional de Mar del Plata; ArgentinaFil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Pérez, Gabriel Horacio. Universidad Nacional de Mar del Plata; Argentin

Large amplitude perturbations and waves at the duskside LLBL of the magnetopause generated by an interplanetary tangential discontinuity on December 7, 2000

On December 7, 2000 a joint current sheet and vorticity layer hit the magnetopause (MP) generating large amplitude oscillations, and wave-like perturbations observed by CLUSTER at the near dusk flank. Linear stability theory and MHD numerical simulations support the hypothesis that the waves were due to the Kelvin-Helmholtz (KH) instability. The simulation brings into light novel dynamical properties of the boundary layer under the KH excitation.Fil: Gratton, Fausto Tulio Livio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Farrugia, C. J.. University of New Hampshire at Manchester; Estados UnidosFil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Gnavi, Graciela Delia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Lund, E. J.. University of New Hampshire at Manchester; Estados Unido

Computational Plasmadynamics applied to parametric studies

A Three-Dimensional Finite Volume Arbitrary Lagrangian-Eulerian simulation code was developed to study different plasma physics problems in 3D+t. The code is based on a complex multi-component species program with transport and radiation terms written and applied to plasma and fusion physics problems. The integration domain is represented with a structured irregular mesh, with fixed connectivity made of hexahedral cells. Coordinates and velocities are assigned to cell vertices. After each calculation cycle, mesh vertices are moved arbitrary over the fluid. The adaptive method consists of shifting mesh vertices over the fluid in order to keep a reasonable mesh structure and increase the spatial resolution where the physical solution demands. The code was a valuable tool for parametric study of different physical problems, mainly optimization of Plasma Focus Machine, detonation and propagation of thermonuclear reactions, and Kelvin-Helmholtz instabilities in the boundary layer of the terrestrial magnetopause. © 2009 IOP Publishing Ltd.Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

A Three-Dimensional Finite Volume Arbitrary Lagrangian-Eulerian code for plasma simulations

A Three-Dimensional Finite Volume Arbitrary Lagrangian-Eulerian simulation code was developed to study different plasma physics problems in 3D+t. The code is based on a complex multi-component species program with transport and radiation terms written and applied to plasma and fusion physics problems. Three different examples are shown: double-base chemical propellant combustion, ignition and propagation of a thermonuclear detonation wave, and, the development of the Kelvin-Helmholtz (KH) instability in local plane slab models of the magnetopause, showing the response of a background equilibrium to the excitation by finite amplitude perturbations generated upstream.A Three-Dimensional Finite Volume Arbitrary Lagrangian-Eulerian simulation code was developed to study different plasma physics problems in 3D+t. The code is based on a complex multi-component species program with transport and radiation terms written and applied to plasma and fusion physics problems. Three different examples are shown: double-base chemical propellant combustion, ignition and propagation of a thermonuclear detonation wave, and, the development of the Kelvin-Helmholtz (KH) instability in local plane slab models of the magnetopause, showing the response of a background equilibrium to the excitation by finite amplitude perturbations generated upstream.Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

Earth rotation via doppler shifts?

Stedman cites many successfully experiments regarding the measurement of the Earth’s rotation via the Sagnac effect. He addresses the important fact that Sagnac measurements can be interpreted as a Doppler effect. In a rotating interferometer all optical components are moving, and therefore each one produces a Doppler shift. Accounting for the total contribution of all the mirrors, the standard Sagnac formula is recovered. We want to clarify the fact that we referred to the value of the Earth’s rotational rate as an example of what we call low rotational speed rather than a proposal to measure the Earth’s rotation by means of our apparatus. As suggested by a reviewer, one could mount the mirror on a motorized rotation stage and move it very slowly. Our apparatus may be used to show students how to detect very low rotational speeds.Fil: Bernal, Luis. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin

Dense magnetized plasma numerical simulations

The scope for developing the present numerical method was to perform parametric studies for optimization of several configurations in magnetized plasmas. Nowadays there exist several efficient numerical codes in the subject. However, the construction of one's own computational codes brings the following important advantages: (a) to get a deeper knowledge of the physical processes involved and the numerical methods used to simulate them and (b) more flexibility to adapt the code to particular situations in a more efficient way than would be possible for a closed general code. The code includes ion viscosity, thermal conduction (electrons and ions), magnetic diffusion, thermonuclear or chemical reaction, Bremsstrahlung radiation, and equation of state (from the ideal gas to the degenerate electron gas). After each calculation cycle, mesh vertices are moved arbitrarily over the fluid. The adaptive method consists of shifting mesh vertices over the fluid in order to keep a reasonable mesh structure and increase the spatial resolution where the physical solution demands. The code was a valuable tool for parametric study of different physical problems, mainly optimization of plasma focus machine, detonation and propagation of thermonuclear reactions and Kelvin-Helmholtz instabilities in the boundary layer of the terrestrial magnetopause. © 2010 IOP Publishing Ltd.Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Bernal, L.. Universidad Nacional de Mar del Plata; Argentin

Measurement and interpretation of electrical signals in transient electrical discharges

Electrical discharges in experiments like Exploding Wire, Plasma Focus, or Z-pinch, involve regions where strong transient electrical currents generates magnetic flux variations within the limits of experiment and diagnostics regions. Due to different experimental conditions, time duration of the transient phase may vary from negligible to play an important role in the explanation of the measured signal of the experiment, in which case Faraday's law of induction cannot be neglected when analyzing the electrical signals. In this work the effects of circuit modeling taking into account Faraday's law will be discussed for the exploding wire experiment in a more detailed way than previous works.Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Rodríguez Prieto, Gonzalo. Universidad de Castilla-La Mancha; Españ