Diagnostics of Hybrid Water/Argon Thermal Plasma Jet with Water, Ethanol and Their Mixture Injection to Plasma

A plasma torch with the water/argon stabilization of an arc is characterized by extremely hot and high velocity plasma together with the relatively low flow rate of plasma, therefore, the torch might be properly used for plasma suspension spraying. Enthalpy probe and emission spectroscopy measurements were carried out at constant arc power with the combination of the injection of water, ethanol or their mixture to the plasma jet to diagnose the changes in temperature, heat flux and other characteristics

Impact of the oxide scale on spray cooling intensity

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Heat treatment of steel is attended by oxide scales growth with various physical properties. The most common and most dominant impact of the oxide scale layers is on the surface quality and mechanical properties of steel. This paper is focused on study of influence of the oxide scale on cooling intensity. Spray cooling is a typical technique used in heat treatment and other metallurgical processes where controlled temperature regimes are required. Cooling intensity is primarily affected by spray parameters as pressure and coolant impingement density. It is not frequently reported but even thin layers of oxides can significantly modify the cooling intensity. This effect is dominant in the cooling of steel surfaces at high surface temperatures. Study of the influence of the oxide scale layers on cooling intensity was carried out by experimental measurements and numerical analysis. Experimental measurements compare the cooling of scale-free surfaces and oxidized surfaces. Experimental investigations show a difference in the cooling intensity. Numerical analyses were prepared to simulate cooling of the samples with different oxide scale layers and different thermal conductivity of scales. Even a scale layer of several microns can significantly modify the cooling intensity. A low thermal conductivity of the oxides can make the cooling more intensive. The paper provides experimental evidence of this fact and numerical study of the oxide scale layer thickness and thermal conductivity on the influence on the spray cooling with boiling. The Leidenfrost phenomenon and change in surface temperature provides key to the explanation why the hot surface covered by the oxides is sometimes cooled more intensively than the clean surface.cf201

Electric field effects on magnetotransport properties of multiferroic Py/YMnO3/Pt heterostructures

We report on the exchange bias between antiferromagnetic and ferroelectric hexagonal YMnO3 epitaxial thin films sandwiched between a metallic electrode (Pt) and a soft ferromagnetic layer (Py). Anisotropic magnetoresistance measurements are performed to monitor the presence of an exchange bias field. When the heteroestructure is biased by an electric field, it turns out that the exchange bias field is suppressed. We discuss the dependence of the observed effect on the amplitude and polarity of the electric field. Particular attention is devoted to the role of current leakage across the ferroelectric layer.Comment: Accepted for publication in Philosophical Magazine Letters (Special issue on multiferroics

Detection of ultra-high energy cosmic ray showers with a single-pixel fluorescence telescope

We present a concept for large-area, low-cost detection of ultra-high energy cosmic rays (UHECRs) with a Fluorescence detector Array of Single-pixel Telescopes (FAST), addressing the requirements for the next generation of UHECR experiments. In the FAST design, a large field of view is covered by a few pixels at the focal plane of a mirror or Fresnel lens. We report first results of a FAST prototype installed at the Telescope Array site, consisting of a single 200 mm photomultiplier tube at the focal plane of a 1 m$^2$ Fresnel lens system taken from the prototype of the JEM-EUSO experiment. The FAST prototype took data for 19 nights, demonstrating remarkable operational stability. We detected laser shots at distances of several kilometres as well as 16 highly significant UHECR shower candidates.Comment: Accepted for publication in Astroparticle Physic

Novel project on total plasma based treatment of waste

An experimental plasmachemical reactor has been started at IPP Prague for the innovative and environmerntally friendly total plasma treatment of waste streams, biomass and low grade fuels, with a view to their sustainable energetic and chemical valorisation and to a reduction of the emission of greenhouse gases. Existing incineration and biological waste elimination processes cannot always fulfil the objectives of sustainable development, i.e. maximum recovery of energy and materials from the waste streams in an environmentally friendly manner. Moreover, these processes often generate residues which are concentrates of hazardous material and need to be landfilled. Plasmas offer an alternative and superior solution for the treatment of waste streams. Plasma torches have the unique capability of increasing the energy of the process gas compared with conventional combustion equipment. They therefore offer several distinct advantages over traditional methods where the energy content of the waste is used as the heat source. Since the process energy is provided by direct heat transfer from an electric arc, gases of widely varying chemical composition may be used; use of electrical energy also reduces the gas flow needs and on-site off-gas production, and offers control over the chemistry. The very high heat conditions in a plasma reactor trigger a dual, simultaneous reaction process: organic materials are converted into synthesis gas (syngas) without formation of toxic products such as dioxins and furans, while inorganic materials are converted into a non-leaching, vitrified, inert slag which has industrial applications. The quality of the syngas can be controlled by non-thermal plasmas, using new generations of gas cleaning corona plasma technologies. A plasmachemical experimental reactor has been commissioned in Prague in August-September 2004, using the novel IPP-CAS hybrid gas-water stabilized torch (160 kW).В ІФП в Празі був запущений експериментальний плазмохімічний реактор з використанням найновіших екологічно чистих технологій для повної плазмової обробки відходів, біомаси та низькосортного палива з урахуванням збереження їх енергетичної і хімічної цінності і зниження викидів парникових газів. Існуючі процеси знищення відходів засобом спалювання та біологічної обробки не завжди забезпечують максимальне відновлення енергії і матеріалів з відходів без завдання шкоди навколишньому середовищу. Крім того, ці процеси часто призводять до створення залишків, що містять небезпечні речовини і підлягають похованню. Плазмові технології пропонують альтернативне и краще рішення задачі переробки рідких відходів. Порівняно зі звичайним обладнанням для спалювання, плазмові факели мають унікальну здібність підвищувати енергію газу, що виділяється під час переробки. Тому вони дають деякі явні переваги над традиційними методами, де енергозміст відходів використовується як джерело тепла. Оскільки процес виділення енергії забезпечується прямим передаванням тепла від електричної дуги, можливе використання газів різноманітного хімічного складу. Використання електричної енергії дозволяє зменшити витрати газу та його супровідне виділення і здійснити хімічний контроль. Сильний нагрів в плазмовому реакторі ініціює два одночасних процеса - перетворення органічних речовин у синтетичний газ (сингаз) без створення токсичних продуктів, таких як діоксини та фурани, а неорганічних речовин – у невилужений склоподібний інертний шлак, що має промислове застосування. Якість сингазу можна контролювати за допомогою нетеплової плазмы за новими плазмовими технологіями очищення газів з вживанням плазмової корони. Плазмохімічний експериментальний реактор з використанням нового гібридного газоводяного стабілізованого факела IPP-CAS (160 квт) прийнятий в експлуатацію в Празі в серпні-вересні 2004 р.В ИФП в Праге запущен экспериментальный плазмохимический реактор с использованием новейших экологически чистых технологий для полной плазменной обработки отходов, биомассы и низкосортного топлива с учётом сохранения их энергетической и химической ценности и снижения выбросов парниковых газов. Существующие процессы уничтожения отходов путём сжигания и биологической обработки не всегда обеспечивают максимальное восстановление энергии и материалов из отходов без ущерба для окружающей среды. Кроме того, эти процессы часто приводят к образованию остатков, содержащих опасные вещества и подлежащих захоронению. Плазменные технологии предлагают альтернативное и лучшее решение задачи переработки отходов. По сравнению с обычным оборудованием для сжигания плазменные факелы обладают уникальной способностью повышать энергию газа, выделяющегося при переработке. Поэтому они дают некоторые явные преимущества над традиционными методами, в которых энергия, содержащаяся в отходах, используется как источник тепла. Так как процесс выделения энергии обеспечивается прямой передачей тепла от электрической дуги, можно использовать газы разнообразного химического состава. Использование электрической энергии позволяет уменьшить потребление газа и его сопутствующее выделение и осуществить химический контроль. Сильный нагрев в плазменном реакторе запускает два одновременных процесса - превращение органических веществ в синтетический газ (сингаз) без образования токсических продуктов, таких как диоксины и фураны, а неорганических веществ – в невыщелоченный стекловидный инертный шлак, имеющий промышленное применение. Качество сингаза можно контролировать с помощью нетепловой плазмы по новым плазменным технологиям очистки газов с использованием плазменной короны. Плазмохимический экспериментальный реактор с использованием нового гибридного газоводяного стабилизированного факела IPP-CAS (160 кВт) принят в эксплуатацию в Праге в августе-сентябре 2004 г

Optical, magneto-optical properties and fiber-drawing ability of tellurite glasses in the TeO2-ZnO-BaO ternary system

The presented work is focused on the optical and magneto-optical characterization of TeO2-ZnO-BaO (TZB) tellurite glasses. We investigated the refractive index and extinction coefficient dispersion by spectroscopic ellipsometry from ultraviolet, 0.193 um, up to mid infrared, 25 um spectral region. Studied glasses exhibited large values of linear (n632 = 1.91-2.09) and non-linear refractive index (n2 = 1.20-2.67x10-11 esu), Verdet constant (V632 = 22-33 radT-1m-1) and optical band gap energy (Eg = 3.7-4.1 eV). The materials characterization revealed that BaO substitution by ZnO leads (at constant content of TeO2) to an increase in linear and nonlinear refractive index as well as Verdet constant while the optical band gap energy decreases. Fiber drawing ability of TeO2-ZnO-BaO glassy system has been demonstrated on 60TeO2-20ZnO-20BaO glass with presented mid infrared attenuation coefficient. Specific parameters such as dispersion and single oscillator energy, Abbe number, and first-/ third-order optical susceptibility are enclosed together with the values of magneto-optic anomaly derived from the calculation of measured dispersion of the refractive index

Temperature and Humidity Dependence of Air Fluorescence Yield measured by AIRFLY

The fluorescence detection of ultra high energy cosmic rays requires a detailed knowledge of the fluorescence light emission from nitrogen molecules over a wide range of atmospheric parameters, corresponding to altitudes typical of the cosmic ray shower development in the atmosphere. We have studied the temperature and humidity dependence of the fluorescence light spectrum excited by MeV electrons in air. Results for the 313.6 nm, 337.1 nm, 353.7 nm and 391.4 nm bands are reported in this paper. We found that the temperature and humidity dependence of the quenching process changes the fluorescence yield by a sizeable amount (up to 20%) and its effect must be included for a precise estimation of the energy of ultra high energy cosmic rays.Comment: presented at the 5th Fluorescence Workshop, El Escorial - Madrid, Spain, 16 - 20 September 2007, to appear in Nuclear Instruments and Methods

A novel method for the absolute fluorescence yield measurement by AIRFLY

One of the goals of the AIRFLY (AIR FLuorescence Yield) experiment is to measure the absolute fluorescence yield induced by electrons in air to better than 10% precision. We introduce a new technique for measurement of the absolute fluorescence yield of the 337 nm line that has the advantage of reducing the systematic uncertainty due to the detector calibration. The principle is to compare the measured fluorescence yield to a well known process - the Cerenkov emission. Preliminary measurements taken in the BFT (Beam Test Facility) in Frascati, Italy with 350 MeV electrons are presented. Beam tests in the Argonne Wakefield Accelerator at the Argonne National Laboratory, USA with 14 MeV electrons have also shown that this technique can be applied at lower energies.Comment: presented at the 5th Fluorescence Workshop, El Escorial - Madrid, Spain, 16 - 20 September 200

Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a number of major breakthroughs. Among these we discuss the energy spectrum and the searches for large-scale anisotropies. We present analyses of our X$_{max}$ data and show how it can be interpreted in terms of mass composition. We also describe some new analyses that extract mass sensitive parameters from the 100% duty cycle SD data. A coherent interpretation of all these recent results opens new directions. The consequences regarding the cosmic ray composition and the properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray Conference, Rio de Janeiro 201