Pulsed Gas Injection Research Articles

Pulse gas injection into the separation zone of hypersonic MHD flow over a rotation body

Pulse gas injection into the separation zone of hypersonic MHD flow over a rotation body

Pulse gas injection into the separation zone of hypersonic MHD flow over a rotation body

Pulse gas injection into the separation zone of hypersonic MHD flow over a rotation body

Electron stripping of Bi ions using a modified 1.4 MeV/u gas stripper with pulsed gas injection

The GSI UNILAC will serve as an injector system for the future Facility for Antiproton and Ion Research (FAIR) facility. To meet the high demands for high-intensity heavy-ion beams, an upgrade of the existing 1.4 MeV/u gas stripper is envisaged with the aim of increasing the stripping efficiency for the required charge state. For this, an increase of the stripping gas density is pursued. Since FAIR will use pulsed beams with a very small duty cycle, a new stripper setup with a pulsed gas injection was implemented to minimize the gas load and thereby enables an increase of the gas pressure. The setup was tested using a bismuth ion beam with a nitrogen gas target. The performance is compared with that of the existing nitrogen gas-jet stripper. The charge stripping of bismuth ions into the same average charge state (26+) was achieved.

Characterization of pulsed capillary channel gas puff target using EUV shadowgraphy

Characterization measurements of a pulsed capillary channel gas puff target, developed for applications in laser-matter interaction experiments, are presented. The target is produced by pulsed injection of gas through a slit-shaped nozzle into a capillary channel and has been characterized by EUV radiography at 13.5nm wavelength. Time dependent gas flow effects and flow shaping by capillary walls were visualized. Density measurements for argon were performed on axis for variable timing conditions and variable backing pressures. This target, due to its advantages, might be an interesting alternative for lower repetition rate and higher energy laser-matter interaction experiments.

Experimental Studies of an Ultrahigh-Speed Plasma Flow

In 1991, Turchi et al. reported evidence for a 2000 km/s aluminum plasma that originated from the upstream boundary of a wire array armature in a plasma flow switch (PFS). The 2008 article by Turchi et al. posits that if such high $Z$ plasma could instead be composed of deuterium or a deuterium–tritium mixture, then the resultant multi-keV plasma would make an effective target for magnetized plasma compression to fusion conditions. This report documents several experiments executed in an effort to achieve an ultrahigh-speed flow in a deuterium plasma. The first phase of this research concentrated on extension of the earlier work to a lower current system that would emulate the PFS used in series with an imploding liner load. The apparatus was also modified to permit pulsed injection of deuterium gas along the insulated coaxial electrodes between the PFS armature and the vacuum power feed. The experiments met with limited success, exhibiting evidence of a 550 km/s plasma flow which convected a small fraction of the total magnetic field. Two subsequent tests were conducted using foam armatures. In both cases, current prematurely shunted upstream in the vacuum feed. Several possible causes were explored for the shunting of the current. Among the modifications implemented, the gas injection system was altered to increase both the quantity of gas adjacent to the armature while facilitating an increased pressure gradient between the armature and the current feed. A series of low-energy shots were conducted to examine the impact of several proposed design modifications on current delivery to the armature. These experiments demonstrated that the hardware assembled for this investigation was unlikely to forestall breakdown in the injected gas as required by Turchi et al. Nevertheless, two experiments were conducted to evaluate performance with foam armatures. Both experiments exhibited good current delivery to the armature, behaving initially like the low-energy experiments. The magnetic flux convected downstream was greater than in any of the prior experiments, though significant work remains to demonstrate the ultrahigh-speed plasma flow concept.

Extreme ultraviolet tomography of multi-jet gas puff target for high-order harmonic generation

A volume, tomographic reconstruction of a novel, multi-jet gas puff target, developed for possible applications in high-order harmonic generation (HHG), is presented. The target, produced by pulsed injection of argon gas through nozzle in a form of linearly oriented small orifices, has been characterized in the extreme ultraviolet at 13.5 nm wavelength. Target density estimations were performed, and 3-D representation of pulsed gaseous target has been obtained by combining 2-D shadowgram images, recorded at various rotation angles. More detailed information about higher-order jets, formed as a result of collisions of primary jets, was obtained. Tomographic studies of such type of targets dedicated for HHG have been obtained to our knowledge for the first time.

The Injection Pattern of Immiscible Nitrogen Displacement After Water Flooding in an Ultra-low Permeability Reservoir

With the nature ultra-low permeable cores from Changqing Oilfield, the simulated experiments of nitrogen drive after water flooding have been accomplished for the ultra–low-permeability reservoir. The injection pattern of nitrogen includes direct gas injection, water/gas alternating injection and pulse gas injection. The results show that direct injection could not develop the ability that nitrogen enters into the local tight area to improve the microsweep efficiency, because the good mobility generates gas channeling in some local high-permeable zone. Subsequent direct nitrogen injection after water drive only enhances the oil recovery ratio by 3.65%. The dispersion degree of oil, water, and gas is much higher for water/gas alternating injection after water injection, and the capillary force is the main resistance to suppress the rapid gas flow validly in local high-permeable zone. Nitrogen is enforced to drive the residual oil in local tight area or micro pore system. Water/gas alternating injection after water flooding enhances oil recovery ratio by 16.37%. Pulsing injection can take advantage of the elastic energy of the high-pressure nitrogen and pressure disturbance effect, which makes pressure redistribution and fluid deallocation between local high-permeability zone and local compact area. With pulse injection, oil in local tight region also can be driven by nitrogen, and the recovery ratio is enhanced by 15.94%.

Investigation of Tungsten Nitride Deposition Using Tungsten Hexafluoride Precursor for Via and Plug Metallization

We investigated a tungsten nitride (WN)-based diffusion barrier layer (DBL) on a Cu metal layer by atomic layer deposition (ALD) using three different treatments, namely, ammonia (NH3) plasma treatment, ammonia (NH3) pulsed plasma treatment, and diborane (B2H6) pulsed gas injection treatment. In an experimental result of a method with B2H6 pulsed gas injection, the fluorine (F) concentration was below 3% in the WN films, and optimum growth conditions, including a linear deposition rate, a few incubation cycles, good thermal stability, and an excellent step coverage of approximately 100%, were observed for the DBL application. These results suggest that the B2H6 pulsed gas injection is a useful method for obtaining high-quality WN films for use as a DBL on a Cu contact via a 15 nm node.

Focus on semiconductors and software

Focus on semiconductors and software

Transmission of N-Atoms Produced by N<sub>2</sub> Flowing Microwave Afterglows through Hollow Tubes

Transmission of N-atoms (T N ) through small diameters tubes (1.5 and 3 mm internal diameter (i.d) and 9, 50 and 80 cm length for silicone tubes, 1.5 mm i.d and 6.5 cm length for stainless steel tubes) has been measured in late N2 and Ar-N2 flowing afterglows of microwave plasmas in continuous and pulsed gas injection at a flow rate of 1 and 3 Standard liter by minute (Slm), a gas pressure from 2 to 4 Torr for N2 and 20 Torr for Ar-1%N2 and a plasma power from 150 to 300 Watt. From the experimental TN values, it is deduced the γ-destruction probability inside the tube walls as being y = (1-1.6)×10-3 for the silicon tubes and y = (1.6-2)×10-2 for the stainless steel tubes.

パルス高速噴射によるセラミック膜形成

Coating techniques utilizing the collision and adhesion of microparticles on a substrate have recently been attracting attention. However, the bonding between particles deposited on the substrate at room temperature and atmospheric pressure is weak because the kinetic energy of particles during their collision with a substrate is small. The aim of this study is to form ceramic films under these conditions, which is considered difficult. Concretely, the pressurized gas at the surface of the workpiece to be processed is released by the pulsed injection of helium gas using alumina microparticles to form coatings, while preventing the collision speed of the alumina microparticles from decreasing. By pulsed gas injection for 5 min, we succeeded in forming 10-µm-thick alumina ceramic films with a hardness of approximately 40% of that of a sintered alumina body. The results of a friction wear experiment indicated that the coefficient of friction of the films was stable and low (0.15). In addition, the quenched steel balls used in the experiment were worn out, demonstrating that the formed films have good abrasion resistance and adhesion.

Reducing the central porosity of continuous-cast billet by modification of the solidification process

The quality of continuous-cast billet is considered. Means of improving billet solidification are developed, with the pulsed injection of inert gas into the metal in the mold and shear-enhanced mild compression of the billet in the secondary-cooling zone of the continuous-casting machine. These measures are found to shrink the columnar-crystal zone and reduce the central porosity.

Characterization of multi-jet gas puff targets for high-order harmonic generation using EUV shadowgraphy

Characterization measurements of multi-jet gas puff targets, developed for investigations on high-order harmonic generation (HHG) by a focused laser beam in a gas medium of modulated density, are presented. The targets produced by pulsed injection of gas through a nozzle in a form of a chain of small orifices have been characterized by EUV backlighting at 13.5nm wavelength. Measurements were performed for nozzles with 5, 7 and 9 orifices of 0.5mm in diameter each. Density profiles for argon targets have been obtained for the first time.

Study on Long-Core Experiment of Gas Driving in Dual-Media Reservoir

Reservoir X is a fractured-porous dual-media reservoir. According to the geological conditions and exploration and development statuses of reservoir X, this paper designs a long-core experiment and then carries it on. As a result, the diffeSubscript textrent enhance displacement efficiency effects under different driving methods (water flooding, gas flooding, WAG, pulsed gas injection, gas slug flooding) and different driving media (flue gas, CO2) are obtained. The results show that among all those driving methods, water alternating CO2 injection (WAG) reaches the best effect. WAG has an injection rate of 0.8HCPV and enhances displacement efficiency by 26.93% on the basis of water flooding. The injection rate of gas slug/water flooding after CO2 slug flooding is 0.3HCPV and these two methods have similar good results, 13.66% and 13.95% respectively. So considering the economic factor, we draw a conclusion that water flooding after CO2 slug flooding is the optimum choice.

A pulsed injection parahydrogen generator and techniques for quantifying enrichment

A device is presented for efficiently enriching parahydrogen by pulsed injection of ambient hydrogen gas. Hydrogen input to the generator is pulsed at high pressure to a catalyst chamber making thermal contact with the cold head of a closed-cycle cryocooler maintained between 15 and 20 K. The system enables fast production (0.9 standard liters per minute) and allows for a wide range of production targets. Production rates can be systematically adjusted by varying the actuation sequence of high-pressure solenoid valves, which are controlled via an open source microcontroller to sample all combinations between fast and thorough enrichment by varying duration of hydrogen contact in the catalyst chamber. The entire enrichment cycle from optimization to quantification and storage kinetics are also described. Conversion of the para spin-isomer to orthohydrogen in borosilicate tubes was measured at 8 min intervals over a period of 64 h with a 12 T NMR spectrometer. These relaxation curves were then used to extract initial enrichment by exploiting the known equilibrium (relaxed) distribution of spin isomers with linear least squares fitting to a single exponential decay curve with an estimated error less than or equal to 1%. This procedure is time-consuming, but requires only one sample pressurized to atmosphere. Given that tedious matching to external references are unnecessary with this procedure, we find it to be useful for periodic inspection of generator performance. The equipment and procedures offer a variation in generator design that eliminate the need to meter flow while enabling access to increased rates of production. These tools for enriching and quantifying parahydrogen have been in steady use for 3 years and should be helpful as a template or as reference material for building and operating a parahydrogen production facility.

Optical Observation of Nitrogen Propagation in Argon Plasma

While the gas flow patterns in reactors can be visualized using models, it has proven that it is difficult to measure them. This paper shows that the gas flow pattern for pulsed injection of nitrogen gas into argon plasma can be readily seen in the optical emission intensity. As N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> enters the Ar plasma, N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> molecules cause increased optical emission intensity by the Penning effect. This allows one to measure the N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> propagation. In this paper, we present the pictures with the measurement details and analysis.

Analysis of a pulsed discharge within single bubbles in water under synchronized conditions

Synchronized generation of single bubbles and an underwater discharge in the bubbles was performed using pulsed injection of feed gas with a piezoelectric valve. The differences in the discharge appearance and the after-effect on the bubble were systematically studied with different kinds of gases. In molecular gases such as N2 and O2, surface discharge along the inner bubble surface predominated and the disturbance caused wrinkles on the bubble surface, while in rare gases, such as He, Ne and Ar, a large hump formed on the smooth surface due to a rather volumetric discharge. When the input power was increased, the discharge sometimes caused the collapse of a single bubble, producing smaller bubbles. It was observed by emission spectra that excited species of OH, H and O radicals were produced in the discharge plasma. The emission intensity ratio of the Hα line to the OH band was larger in He and Ne gases than in other gases, suggesting differences in the dissociation channels.

The Present State of Investigations on Stellarators in Kharkov

At present, two stellarator type fusion devices, Uragan-2 M and Uragan-3 M, are in operation in Kharkov. At the Uragan-3 M machine, investigations of the low-density low-collisional plasma are continued. L-H-mode-like transition is studied with particular attention to the mechanisms of its formation and impact on divertor flow behaviour. For a higher density plasma, a scenario of the RF Alfven resonance heating in high k|| regime is realized both with continuous and pulsed gas injection. On Uragan-2 M the studies of RF wall conditioning are in progress. A new wall conditioning scheme which uses the high frequency slow wave is implemented.

Optimization of the Stockholm R-EBIT for production and extraction of highly charged ions

We describe a refrigerated EBIT (R-EBIT) commissioned at the AlbaNova Research Center at Stockholm University. As an innovative solution, the superconducting magnet and the trapping drift tubes of the R-EBIT are cooled to a temperature of 4 K by a set of two cooling heads connected to helium compressors. This dry, i.e. liquid helium and liquid nitrogen free, system is easily operated and creates highly charged ions at a fraction of the cost of traditional liquid-cooled systems. A pulsed and continuous gas injection system was developed to feed neutral particles into the electron beam in the trap region. This improves significantly the highly charged ion production and R-EBIT performance. Fast extraction of ions from the R-EBIT yields very short ( < 100 ns), charge-separated ion bunches which can be either analysed using a straight time-of-flight section or sent to experimental beam lines following selection in a bending magnet. An emittance meter was used to measure the emittance of the ions extracted from the R-EBIT. The extracted ions were also re-trapped in a cylindrical Penning trap and properties of the re-trapped ions have been measured using the emittance meter. Results of these measurements are reported in this publication.

Properties of TiN coatings deposited by the modified IPD method

The paper describes the very first observations of the effect of pulsed gas injection to the coaxial accelerator during impulse plasma deposition (IPD) on the structure and properties of deposited material. As a test material a TiN coating deposited on high-speed steel substrates was chosen. The morphology and wear-resistance properties were determined. The structure obtained with modified IPD method is characterized by a crystalline structure built of rectangular nanograins (with size a few tens of nm) in contrast to the nanocrystalline structure based on three-dimensional (3D) agglomerates of nanoparticles typical for the standard IPD synthesis. The wear-resistance of the TiN coatings deposited in the modified IPD apparatus demonstrate very good properties with the best results more than ten times better compared with the uncoated steel substrates.