J Torres

An easy way to determine simultaneously the electron density and temperature in high-pressure plasmas by using Stark broadening

This paper discusses the possibility of determining, at the same time, both the electron density and temperature in a discharge produced at atmospheric pressure using the Stark broadening of lines spontaneously emitted by a plasma. This direct method allows us to obtain experimental results that are in good agreement with others previously obtained for the same type of discharge. Its advantages and disadvantages compared to other direct methods of diagnostics, namely Thomson scattering, are also discussed.

How do numbers begin? (The first digit law)

In this letter, a brief historical review of the first digit law, discovered first by Newcomb and later by Benford, is presented. This law gives information about the frequency of the appearance of each number as the first significant digit in a surprisingly large number of different data sets. Some of the main theoretical advances and useful applications of the law are described. In addition, graphical examples of different kinds are discussed.

Multiple diagnostics in a high-pressure hydrogen microwave plasma torch

We present an experimental study of a hydrogen plasma produced by a microwave axial injection torch, launching the plasma in a helium-filled chamber. Three different diagnostic methods have been used to obtain the electron density and temperature as follows: The Stark intersection method of Balmer spectral lines (already tested in argon and helium plasmas); the modified Boltzmann-plot showing that the plasma is far from the local thermodynamic equilibrium but ruled by the excitation-saturation balance; and a study by the disturbed bilateral relations theory. All of these diagnostic techniques show a good agreement.

Characterization of a high-pressure hydrogen microwave plasma torch using the method of dBR

A hydrogen plasma flame produced by an axial injection torch powered at the microwave frequency of 2.45 GHz is studied using the method of disturbed Bilateral Relations (dBR). The application of this method which relates the influence of equilibrium disturbing, as produced by transport, to equilibrium restoring processes, reveals that the most dominant excitation balance is the Excitation Saturation Balance. Moreover, a global discharge model leads to an electron density of ne = 4.1020m?3 and an electron temperature of Te = 0.86 eV. The gas temperature was estimated to be Th = 0.3 eV. The values of ne and Te were found to be in good agreement with the value obtained with the modified Boltzmann-plot and the crossing method of Stark broadening. The dBR method points out that the first level in partial local Saha equilibrium will be the level with principal quantum number p = 10 which is in fair agreement with experimental results.

Experimental characterization of the Hβ-line profiles in microwave-produced plasmas at atmospheric pressure

An experimental study on the asymmetry of the Balmer Hβprofile in plasmas produced by microwaves at atmospheric pressure is presented. The study is based on the definition of several functions and parameters that quantify the asymmetry and different shape aspects of the profile. The study shows the experimental dependence of these characteristics on the electron density and control parameters such as the gas flow and the hydrogen admixture ratio. The possible use of these newly introduced profile characteristics to plasma diagnosis is discussed.

Balmer-β Line Asymmetry Characteristics in a High Pressure, Microwave-Produced Argon Plasma

This paper presents a study on the asymmetry of the Balmer Hβ profile in plasmas produced by microwaves at high pressure with the help of some functions of asymmetry for the whole profile, as well as by means of some specific parameters characterizing only its central dip. The study shows how this asymmetry—very low in our case—depends on the electron density and flux of gases and how the existence of inhomogeneities in the plasma can affect the shape and symmetry of this line. Also, limitations on the determination of the asymmetry are pointed out and the use of this profile for plasma diagnosis is discussed.

Experimental characterization of the asymmetry and the dip form of the Hβ-line profiles in microwave-produced plasmas at atmospheric pressure

An experimental study on the asymmetry of the Balmer Hβ profile in plasmas produced by microwaves at atmospheric pressure is presented. The asymmetry of the whole profile is studied with the help of one function that quantified this characteristic. The asymmetry and shape of the central valley is also studied with the definition of several parameters. The study shows the presence of the Stark asymmetry in plasmas with electron density of the order of 1021m−3.