Study of Argon Afterglow with the Air Addition

The reaction kinetics in argon flowing afterglow (post-discharge) with the air addition was studied by optical emission spectroscopy. The optical emission spectra were measured along the~post-discharge flow tube. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows to calculate the time dependencies of particle concentrations

Generation of Silver Nanoparticles by the Pin-Hole DC Plasma Source with and without Gas Bubbling

Silver nanoparticles were produced using the pin-hole discharge generated by dc non-pulsing high voltage directly in silver nitrate solutions. Sodium nitrate was alternatively added to increase solution conductivity and decrease input energy for the discharge breakdown. Argon or oxygen was bubbled through the discharge region. Comparative experiments were evaluated by UV-VIS spectrometry. Formation of silver nanoparticles with the average size of 100 nm was confirmed by SEM/EDS analysis

Diagnostics of Nitrogen-methane Atmospheric Glow Discharge Used for a Mimic of Prebiotic Atmosphere

The exploration of planetary atmosphere is being advanced by the exciting results of the Cassin-Huygens mission to Titan. The complex chemistry revealed in such atmospheres leading to the synthesis of bigger molecules is providing new insights into our understanding of how life on Earth developed. This work extends our previous investigation of nitrogen-methane (N2-CH4) atmospheric glow discharge for simulation chemical processes in prebiotic atmospheres. In presented experiments 2 % of water vapor were addet to nitrogen-methane gas mixture. Exhaust products of discharge in this gas mixture were in-situ analysed by Fourier Transform Infra Red spectroscopy (FTIR). The major products identified in spectra were: hydrogen cyanide, acetylene and acetonitrile

SAMPLE TEMPERATURE DURING CORROSION REMOVAL BY LOW PRESSURE LOW-TEMPERATURE HYDROGEN RF PLASMA

Abstract. The plasma chemical reduction of corrosion layers from archaeological metallic objects is developing since the late 70 th . Contemporary, it is used in some museums, but the optimal treatment conditions are not fully known yet. Treated object temperature is one of the most critical points because metallographic changes can be initiated by elevated temperatures and thus the unique historical information can be lost. Temperature increases due to the direct inductive heating in the discharge as well as by the interaction of the surface with plasma active particles. In the case of samples prepared in acidic corrosion environment, the maximal temperature of the samples with the incrustation was lower than of samples without incrustation treated under the same conditions because the incrustation layers decrease the direct interaction of plasma active particles with the corrosion layers. In contrary, in the case of brass samples prepared in the ammonia atmosphere, the incrustation had an opposite effect due to intense heating of the sample during the reaction with oxygen presented in the outer corrosion layers. The maximal sample temperature was directly proportional to the linear size (or the third root of weight) of the treated sample

Intenzita záření a teplota vyhasínajícího stejnosměrného výboje v směsi dusík-kyslík

This contribution focuses on the oxygen influence to the pure nitrogen post-discharge. The DC flowing afterglow in Pyrex tube at discharge current of 150 mA and pressure of 1000 Pa was studied by optical emission spectroscopy at decay times in the range of 3 – 45 ms. Band head intensities of 1st and 2nd positive and 1st negative nitrogen spectral systems were observed as a function of oxygen admixture ( 0-5000 ppm). The nitrogen pink afterglow effect was observed in all cases. Temperature during the afterglow was determined by two different ways. The first one was the direct calculation of the rotational temperature of nitrogen 1st positive 2-0 band using numeric simulation. The second way was the strongly temperature-sensitive ratio of band head intensities originating from 11 and 12 vibrational levels of N2 (B 3g) state because these levels were populated during the afterglow mainly by the atomic nitrogen recombination

Pink afterglow in nitrogen-argon mixtures

The nitrogen pink afterglow was studied by optical emission spectroscopy in the DC flowing regime at a total gas pressure of 700 Pa and at the discharge current of 120 mA. The discharge was created in a Pyrex tube of 13 mm i.d. using nitrogen and argon of 99.999% purity with additional purification by Oxiclear columns and liquid nitrogen traps. The area ±3 cm around the observation point had to be cooled down to liquid nitrogen wall temperature in order to allow the study of the reactor wall temperature effect on the post-discharge. The maximum pink afterglow emission in pure nitrogen at ambient wall temperature was observed at a decay time of 6 ms. When the argon percentage in the gas mixture was increased the pink emission maximum was shifted to the later decay times. Simultaneously, the intensity of the pink afterglow decreased and at a 1:1 nitrogen-argon ratio the effect disappeared. Similar effects were also observed when the discharge tube wall around the observation point was cooled down to liquid nitrogen temperature. The argon atomic lines were only observed during the post-discharge at the highest argon concentration at a low wall temperature. The kinetic model showed that the pink afterglow quenching was connected to the decrease of the $v\!\!-\!\!v$ and pooling processes efficiency