Experimental Study of Effects of the Internal Inductance on the Energy Confinement Time in IR-T1 Tokamak

In this paper we present an experimental study of effects of the internal inductance on the energy confinement time, in IR-T1 tokamak. For this purpose, four magnetic pickup coils were designed, constructed, and installed on the outer surface of the IR-T1, and Then Shafranov parameter (asymmetry factor) is obtained from them. On the other hand, also diamagnetic loop were constructed and installed on IR-T1, and poloidal Beta is determined from it. Therefore, the internal inductance obtained. Also, energy confinement time is obtained using diamagnetic loop. Experimental Results show that maximum energy confinement time (which correspond to minimum collisions, minimum microinstabilities, and minimum transport) in IR-T1, relate to the low values of internal inductance (\( 0.61 \, < \, li \, < \, 0.72 \)). This is agreement with theoretical approach.     

Theoretical and Experimental Approach in Poloidal Beta and Internal Inductance Measurement on IR-T1 Tokamak

Measurements of poloidal beta β _p and internal inductance l _i are essential in tokamak plasma research. Much more plasma parameters such as the plasma current density profile, magnetohydrodynamics instability, and plasma energy confinement time are determined by using these parameters. Discrete poloidal magnetic probes along with the diamagnetic loop can be utilized in measurement of the plasma poloidal beta β _p and internal inductance l _i . In this paper, theoretical and experimental results in determining β _p and l _i are presented and discussed.     

Effects of Resonant Helical Field on Plasma Internal Inductance in IR-T1 Tokamak

Measurement of plasma internal inductance is important in tokamak plasma experiments (plasma internal inductance relates to the plasma current profile). In this paper we present an experimental investigation of effects of Resonant Helical Field (RHF) on the plasma internal inductance in IR-T1 tokamak. For this purpose, four magnetic probes and also a diamagnetic loop with its compensation coil were constructed and installed on outer surface of the IR-T1 tokamak, and Shafranov parameter, poloidal Beta, and then the internal inductance determined. In order to investigate the effects of RHF on internal inductance, we measured it in presence and also in absence of different modes of the RHF (L = 2, L = 3, L = 2&3). Experimental results show that L = 3 mode can flat the plasma current and increase the plasma internal inductance.     

Low Dissipation with Normalized Flux Surfaces in 2-Dimensional Coordinate for IR-T1 Tokamak Using Grad–Shafranov Equation Solution

Together with the problem of confinement, plasma–wall interactions present the major constraints toward a magnetic fusion reactor. The solutions of Grad–Shafranov equation (GSE) analytically can be used for theoretical studies of plasma equilibrium, transport and magneto-hydrodynamic stability. Here we introduce specific choices for source functions, kinetic pressure and poloidal plasma current, to be quadratic in poloidal magnetic flux and derive an analytical solution for GS equation. With applying this solution to IR-T1 tokamak, we have calculated the poloidal magnetic flux, toroidal current density and normalized pressure profiles for this tokamak. Toroidal and poloidal flows can considerably change the equilibrium parameters of tokamak. These effects on the equilibrium of tokamak plasmas are numerically investigated using a code FLOW. As a comparative approach to equilibrium problem, the code is used to model equilibrium of IR-T1 tokamak for case pure toroidal flow.     

The Effects of Percent and Position of Nitrogen Atoms on Electronic and Thermoelectric Properties of Graphene Nanoribbons

Graphene-based nanostructures exhibit electronic properties that are not present in extended graphene. Graphene nanoribbons (GNRs) are expected to display extraordinary properties in the form of nanostructures. The effect of percent and position of nitrogen atoms on electronic and thermoelectric properties of a GNR is studied using Landauer approach and density functional theory. For this purpose the density of States, electronic current and thermal current have been calculated. Moreover, an analytical model for the thermo-conductance of the nanosized junction in two-dimensional graphene nanosystems developed. The results show that increasing of nitrogen atoms, increases the splitting of p-orbitals as well as band gap at Fermi level. Also the presence of nitrogen impurities is shown to yield resonant backscattering, whose features are strongly dependent on the position of the dopants. It is demonstrated that increasing N concentration decrease the thermal conductivity due to multi-scattering. In addition I–V characteristics exhibit robust nonlinear behaviors, which are strongly dependent on the position and theconcentration of the nitrogen atoms.     

Energieeffiziente Wärmebehandlung der Gusslegierungen AlSi7Mg0,3 und AlSi9Cu3(Fe)

In this research work, a modified energy efficient T6 heat treatment was performed on AlSi7Mg0.3 and AlSi9Cu3(Fe) castings produced on pilot scale, where a part of the heat from the casting process was used during solution annealing. Calculations of the possible energy savings showed that the novel energy saving heat treatment can gain up to 260 kJ of thermal energy per kilogram of casting compared to conventional methods. To produce samples of the energy efficient heat treatment, the castings were ejected from the squeeze casting machine at 300?°C and immediately transferred to the annealing furnace and subsequently water quenched and artificially aged.     

Efficient and Thermally Stable Wide Bandgap Perovskite Solar Cells by Dual-Source Vacuum Deposition

Wide bandgap perovskites are being widely studied in view of their potential applications in tandem devices and other semitransparent photovoltaics. Vacuum deposition of perovskite thin films is advantageous as it allows the fabrication of multilayer devices, fine control over thickness and purity, and it can be upscaled to meet production needs. However, the vacuum processing of multicomponent perovskites (typically used to achieve wide bandgaps) is not straightforward, because one needs to simultaneously control several thermal sources during the deposition. Here a simplified dual-source vacuum deposition method to obtain wide bandgap perovskite films is shown. The solar cells obtained with these materials have similar or even larger efficiency as those including multiple A-cations, but are much more thermally stable, up to 3500 h at 85 °C for a perovskite with a bandgap of 1.64 eV. With optimized thickness, record efficiency of >19% and semitransparent devices with stabilized power output in excess of 17% are achieved.     

Growth and Characterization of Tungsten Oxide Thin Films using the Reactive Magnetron Sputtering System

WO₃ thin film is one of the most important and applied metal oxide semiconductors that have attracted the scientist’s attention in recent decades. WO₃ thin films by two different methods: reactive and non-reactive RF magnetron sputtering deposited on soda lime glass. The effect of presence and absence of oxygen gas in system and RF power on structural, morphological and optical properties of thin films were investigated. The XRD analysis of the films shows the amorphous structure. Spectrophotometer analysis and calculation show that the optical properties of reactive sputtered layers were better than the non-reactive sputtered thin films. By changing deposition parameters, over 70 % transmission achieved for WO₃ films. The results showed that reactive sputtering method improved the optical properties of layers and increased band gap up to 3.49 eV and on the other hand reduced roughness of thin films. On the whole, presence of oxygen in the chamber during sputtering improved properties of WO₃ thin films.     

Suction-enhanced siphon valves for centrifugal microfluidic platforms

In traditional centrifugal microfluidic platforms pumping is restricted to outward fluid flow, resulting in potential real estate issues for embedding complex microsystems. To overcome the limitation, researchers utilize hydrophilic channels to force liquids short distances back toward the disk center. However, most polymers used for CD fabrication are natively hydrophobic, and creating hydrophilic conditions requires surface treatments/specialized materials that pose unique challenges to manufacturing and use. This work describes a novel technology that enjoys the advantages of hydrophilic fluidics on a hydrophobic disk device constructed from untreated polycarbonate plastic. The method, termed suction-enhanced siphoning, is based on exploiting the non-linear hydrostatic pressure profile and related pressure drop created along the length of a rotating microchannel. Theoretical analysis as well as experimental validation of the system is provided. In addition, we demonstrate the use of the hydrostatic pressure pump as a new method for priming hydrophobic-based siphon structures. The development of such techniques for hydrophobic fluidics advances the capabilities of the centrifugal microfluidic platform while remaining true to the goal of creating disposable polymer devices using feasible manufacturing schemes.     

RETRACTED ARTICLE: A Review on Nanoporous Gallium Nitride (NPGaN) Formation on P-Type Silicon Substrate with the Mather-type Plasma Focus Device (MPFD)

A Mather-type plasma focus device (MPFD) was unitized to fabricated porous gallium nitride (GaN) on p-type silicon (Si) substrate with a <100> crystal orientation for the first time in a deposition process. GaN was deposited on Si with four and seven shots. The samples went through a three phase annealing procedure. First, the semiconductors were annealed in the PFD with nitrogen plasma shots after their deposition, second, a thermal chemical vapor deposition (TCVD) annealed the samples for 1 at 1050?°C by nitrogen gas at 1 Pa pressure. Finally, an electric furnace annealed the samples for 1 h at 1150?°C with continues flow of nitrogen. Porous GaN structures were observed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). Furthermore, X-ray diffraction (XRD) analyze was carried out to determine the crystallinity of GaN after the samples were annealed. Energy-dispersive X-ray spectroscopy (EDX) indicated the amount of gallium, nitrogen, and oxygen due to self-oxidation of the samples. Photoluminescence (PL) spectroscopy revealed emissions at 2.94 and 3.39 eV which shows hexagonal wurtzite crystal structures was formed.