Influence of plasma chemistry on oxygen triplets

The plasma chemistry of fluorocarbon-oxygen-argon discharges and its influence on prominent oxygen triplets are studied. The oxygen 777 triplet is very important for the measurement of atomic oxygen in low pressure plasmas, since the 777.417 nm spectral line is frequently used for actinometry. In this paper we identify changes in the individual 777 triplet lines arising from cascade effects from higher energy levels of oxygen, and from resonant energy transfer from energetic carbon atoms in carbon-rich plasmas. The lower energy levels of three oxygen triplets (544 nm, 616 nm, 645 nm) are the upper states of the 777 triplet. Increased emission intensity from the 544, 616, and 645 triplets result in changes to the relative intensity of the individual lines of the 777 triplet, and this can lead to errors in using the 777 triplet, e.g. for actinometry. Also, in operational conditions with strong carbon emission (around 601 nm), the relative intensity of the individual oxygen 777 lines is affected. The upper energy levels of these carbon lines is close to the oxygen 777 upper energy levels, suggesting that resonant energy transfer between the carbon and the oxygen is occurring. The experiments are performed in a commercial semiconductor dielectric etcher operating with dual rf frequencies of 2 MHz and 27 MHz. Pressure (13-19 Pa), rf power (200-1200 W), and gas mixtures (argon with addmixtures of 5-13% oxygen and C4F8) are typical in application to dielectric etching

On the Stark Broadening Parameters of the Two NII Spectral Lines of the 3d-4f Transition

Stark parameters (width and shift) of two singly ionized nitrogen spectral lines, that belong to 3d-4f transition have been measured in a linear pulsed, low pressure, arc discharge in the nitrogen-oxygen plasma at a 54000 K electron temperature and at a 2.8×10 23 m−3 electron density. The measured values have been compared to the existing experimental and calculated dat

Stark Width and Shift of the Neutral Argon 425.9 nm Spectral Line

The Stark parameters, the width (W) and the shift (d), of the neutral argon (Ar I) 425.9 nm spectral line have been studied in a linear, low-pressure, optically thin pulsed arc discharge. The line shapes are measured in three different plasmas at about 16,000 K electron temperature (T) and about 7.0×1022 m−3 electron density (N). The separate electron and ion contributions to the total Stark width (Wt), i.e. We and Wi, as well as to the total Stark shift (dt), i.e. de and di, have also been obtained and represent new experimental data in this field. On the basis of the observed asymmetry of the Stark broadened line profile we have deduced the ion broadening parameters, which describe the influence of the ion static (A) and the ion-dynamical effect on the width (D) and on the shift (E) of the line shape. Stronger influence of the ion contribution on the 425.9 nm Ar I line shape than is the one predicted by current theory has been evidenced. On the basis of the accurately recorded 425.9 nm Ar I line shape (in the 4s′–5p′ transition), the basic plasma parameters, i.e. electron temperature (T) and electron density (N) have been recovered. This has been achieved by applying the recently developed line deconvolution procedure. The plasma parameters (T and N) have also been measured using independent diagnostics techniques

Experimental and Calculated Stark Widths Within the Kr I Spectrum

On the basis of the precisely recorded 20 neutral krypton (Kr I) line shapes (in the 5s−5p and 5s−6p transitions), we have obtained the basic plasma parameters, i.e., electron temperature (T) and electron density (N) using our line deconvolution procedure in a plasma created in a linear, low-pressure, pulsed arc discharge operated in krypton. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends our deconvolution procedure for plasma diagnostical purposes, especially in astrophysics where direct measurements of the main plasma parameters (T and N) are not possible. On the basis of the observed asymmetry of the Stark broadened line profile, we have obtained not only its ion broadening parameter (A) which is caused by influence of the ion-microfield over the line broadening mechanism but also the influence of the ion-dynamic effect (D) over the line shape. The separate electron (We) and ion (Wi) contributions to the total Stark width, which have not been measured so far, have also been obtained. Stark widths are calculated using the semiclassical perturbation formalism for electrons, protons, and helium ions as perturbers

Surface and Underground Water Level Monitoring Using Wireless Sensor Node with Energy Harvesting Support

In this paper development and testing of a wireless sensor node that is powered by solar energy harvesting is described. Implemented wireless sensor node is characterized by low cost and consumption, long mean time between maintenance, simplicity, flexibility, modularity and miniature design in applications for monitoring of environmental parameters. As a replacement for relatively expensive battery supply and in order to minimize maintenance costs, energy harvesting solution that uses a miniature solar panel and supercapacitor is tested. This node is used for measurements of water levels of surface and underground waters for application in agriculture. For this purpose the node is expanded with a capacitive sensor for measurement of water levels, which is particularly discussed in this paper as simple and innovative solution

Evaluation of the Effect of Plasma Treatment Frequency on the Activation of Polymer Particles

This study investigates the influence of treatment frequency (1–150 kHz) on the atmospheric plasma activation of both silicone and polyethylene terephthalate (PET) particles. These polymer particles with diameters in the range 3–5 mm, were treated using either helium or helium/oxygen gas mixtures, in a barrel atmospheric plasma system. The level of polymer particles activation was monitored using water contact angle measurements. The effect of plasma treatment frequency on barrel heating was monitored using an infrared thermographic camera, the maximum barrel temperature after 15 min treatment was found to be 98 °C at a frequency of 130 kHz. Optical emission spectroscopy was used as a diagnostic tool to monitor changes in atomic and molecular species spectral intensity with experimental conditions, as well as a change in electron energy distribution function. Electrical characterisation studies demonstrated an increase in plasma power with increasing frequency, in the range investigated. X-ray photoelectron spectroscopy analysis indicate an increase of oxygen content on polymer surfaces after plasma treatment. For silicone particles, the minimum polymer water contact angle was obtained by using a frequency of 130 kHz. After 15 min treatment time, the water contact angle decreased from 141° to 11°. While for PET particles the optimum treatment frequency was found to be 70 kHz, resulting in a water contact angle decreased from 94° to 32°. This lower frequency was used due to the partial melting of the PET (Tg of 80 °C), when treated at the higher frequency

Diagnostics of an O2–He RF Atmospheric Plasma Discharge by Spectral Emission

In this paper optical emission spectroscopy (OES) is used as a Diagnostic technique for the measurement of atomic and molecular spectral emissions generated using a helium rf industrial atmospheric plasma jet system. The OES of neutral atomic spectral lines and molecular bands are investigated over a range of plasma process parameters.Wavelength resolve optical emission profiles suggest that the emission of helium’s spectral lines shows that the high energy electrons have a larger influence than helium metastables on the overall spectral emission. Furthermore, the experimental data indicates that the use of high helium flow rates, in any confined open air plasma discharge, limits thesignificance of air impurities, e.g., nitrogen, for the creation and sustainability of plasma discharges in helium–oxygen gas chemistry

Impact of atmospheric pressure nonequilibrium plasma discharge on polymer surface metrology

Due to the attraction of plasma technologies as a clean and efficient means of surface modification, significant research has gone into the physical and chemical aspects of polymer functionalization. In this study, it was shown that the use of an atmospheric plasma jet can efficiently modify the surface of polyethylene terephthalate samples and change their hydrophobic properties to more hydrophilic characteristics. The dependence on the changes with respect to time, distance, and atomic oxygen (O I) intensity were considered as factors. It was found that with closer proximity to the plasma source (without causing thermal degradation) and with increasing levels of O I, that the changes of water contact angle and surface free energy can be maximized. It was also observed that the electron energy distribution function, for a given chemistry, significantly differed with changes in distance from the jet nozzle. This shows that for this type of plasma jet system, the bulk of the chemical reactions occur in the nozzle of the jet and not in the surrounding atmosphere. Therefore, this leads to more efficient energy transfer, higher gas temperatures, and better surface activation of samples when compared to systems that produce external chemical reactions due to more diffusion in the surrounding atmosphere and loss of reactive species to other atoms and molecules that are present

Evaluation of a reel-to-reel atmospheric plasma system for the treatment of polymers

Plasma treatments are widely used to enhance the surface energy of polymers prior to bonding or the application of functional coatings. This study investigates the performance of a linear atmospheric pressure plasma source for the reel-to-reel treatment of polymer webs. The continuous argon plasma treatments were carried out on 15 cm diameter polyethylene terephthalate (PET) web substrates using the linear plasma source (Plamax), operating at 13.56 MHz. The study investigated how the processing parameters influenced the effectiveness of the plasma treatment in enhancing both the polymer web\u27s water contact angle (WCA) and surface energy (SE). Based on these measurements the plasma treatment was found to yield a homogeneous level of activation across the 15 cm web, using a treatment speed of 0.9 m/min. The plasma discharge was monitored using both thermal imaging and optical emission spectroscopy (OES). The latter demonstrated how the oxygen species which diffuse into the argon plasma due to air ingress, were directly correlated with the level of polymer activation

Significance of a Non-Thermal Plasma Treatment on LDPE Biodegradation with Pseudomonas Aeruginosa

The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of 4% CO2, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface. It was, however, found that the use of this slight addition of CO2 aided in the biodegradation of the LDPE samples more than with solely ambient air as the carbon bonds measured from Raman spectroscopy were seen to decrease even more with this change in gas composition and chemistry. The results show that the largest increase of polymer degradation occurs when a voltage of 32 kV is applied over 300 s and with a mixture of ambient air and CO2 in the ratio 25:1