Pulsed Injector Research Articles

Particulate removal characteristics of commercial-scale DeNOx catalyst cartridge coupled filter bags

The commercial-scale DeNOx catalyst cartridge coupled with filter bag have been developed for the removal of fine particulate matter and nitrogen oxides (NOx) in flue gases. The DeNOx catalyst cartridge coupled filter bag is made up of a microporous PTFE (polytetrafluoroethylene) membrane/impregnated polyimide fiber needle-punched pleated filter bag designed for the removal of ultrafine particulates, along with a pellet selective catalytic reduction catalyst-filled cartridge for the removal of NOx. V2O5-MoO3/TiO2 catalyst was used as the DeNOx catalyst. The distribution of cleaning air velocity inside the DeNOx catalyst cartridge-coupled filter bag, which is injected with compressed air from the high-volume low-pressure (HVLP) pulse injector to remove the deposited dust cake from the surface of the filter bags during pulse-jet cleaning, was confirmed using computational fluid dynamics (CFD). The particulate removal and dust cake dislodgement characteristics of the DeNOx catalyst cartridge coupled filter bag were tested in a commercial-scale filter bag test unit under conditions simulating fossil fuel combustion flue gas. The commercial-scale DeNOx catalyst cartridge coupled filter bag was 165 mm in diameter, 2000 mm in total length, and contained approximately 12 kg of DeNOx catalyst- filled cartridges. Nine commercial-scale DeNOx catalyst cartridge coupled filter bags were installed in the commercial-scale filter test unit. The experimental conditions were as follows: flue gas temperature 200 °C, flue gas flow rate 3000Nm3/h, NO, SO2, and particulate concentration in inflow flue gas 200 ppm, 7 ppm, and 5000 mg/Nm3 respectively, resulting in different values of filtration velocities. The efficiency of bag cleaning and intervals, overall collection efficiency, fractional efficiency, and filter quality were investigated. The average bag cleaning efficiency and overall collection efficiency were 95.5%, 91.5%, and 83.3% at filtration velocities of 0.8, 1.0 and 1.2 m/min, respectively. The corresponding values for overall collection efficiency were 99.9%, 99.5%, and 98.2%. So, both bag cleaning efficiency and overall collection efficiency decreased with increased filtration velocity. The present study confirmed that DeNOx catalyst cartridge coupled filter bags have relatively higher bag cleaning efficiency, collection efficiency, and filter quality for challenging fossil fuel combustion flue gas. Particularly, the fractional efficiency for micron-sized particles was considerably higher at lower filtration velocities.

Observation of Monoenergetic Electrons from Two-Pulse Ionization Injection in Quasilinear Laser Wakefields

The generation of low emittance electron beams from laser-driven wakefields is crucial for the development of compact x-ray sources. Here, we show new results for the injection and acceleration of quasimonoenergetic electron beams in low amplitude wakefields experimentally and using simulations. This is achieved by using two laser pulses decoupling the wakefield generation from the electron trapping via ionization injection. The injection duration, which affects the beam charge and energy spread, is found to be tunable by adjusting the relative pulse delay. By changing the polarization of the injector pulse, reducing the ionization volume, the electron spectra of the accelerated electron bunches are improved.

Thrombectomy approach for access maintenance in the end stage renal disease population: a narrative review.

This article reviews current practices and outcomes in endovascular thrombectomy techniques for the treatment of thrombosed arteriovenous grafts (AVGs) and fistulas (AVFs). Arteriovenous (AV) access allows patients with end-stage renal disease (ESRD) to receive hemodialysis. Thrombosis of AV access can lead to delay in hemodialysis or abandonment of access requiring dialysis catheter placement. Endovascular approach has become the preferred treatment option for thrombosed access over surgery. Interventions include removal of thrombus from the AV circuit and treatment of the underlying anatomical abnormality, such as an anastomotic stenosis. Thrombolysis, or the act of dissolving thrombus, is performed by using infusion catheters or pulse injector devices for the administration of fibrinolytic agents. Thrombectomy, or the mechanical removal of thrombus, is performed by using embolectomy balloon catheters, rotating baskets or wires, rheolytic and aspiration mechanisms. Adjunctive methods such as cutting balloon angioplasty, drug-coated balloon (DCB) angioplasty, and stent placement are also used to treat stenoses in the AV circuit. Complications of these procedures include vessel rupture, arterial embolism, pulmonary embolism (PE), and paradoxical embolism to the brain. This narrative review article was written based on literature search from electronic databases, including PubMed and Google Scholar. The understanding of thrombectomy techniques and their potential complications is essential in the management of patients with thrombosed AV access.

Electron beam acceleration using Colliding pulses injection in parabolic plasma channel

optical injection of electrons in laser wakefield accelerator scheme has been shown using the PIC simulation of colliding pulse injection method. Parameter scans like laser polarization, colliding angle, delay and injector pulse intensity have been carried out, to get the optimum values for the injection. To guide the laser pulse over many Rayleigh lengths a parabolic plasma channel is used. For a 45 fs laser pulse of intensity 9 × 1018 W/cm2 focused to spot size of 6 µm inside a plasma of density 4.0 × 1018 cm−3, a highly mono-energetic electron beam with 2.1 pC charge at 337 MeV was obtained.

Subfemtosecond Wakefield Injector and Accelerator Based on an Undulating Plasma Bubble Controlled by a Laser Phase.

We demonstrate that a long-propagating plasma bubble executing undulatory motion can be produced in the wake of two copropagating laser pulses: a near-single-cycle injector and a multicycle driver. When the undulation amplitude exceeds the analytically derived threshold, highly localized injections of plasma electrons into the bubble are followed by their long-distance acceleration. While the locations of the injection regions are controlled by the carrier-envelope phase (CEP) of the injector pulse, the monoenergetic spectrum of the accelerated subfemtosecond high-charge electron bunches is shown to be nearly CEP independent.

DEKA VII Multipoint Fuel Injector Characteristics Study

A saturated injector driver is a power transistor driver circuit that turns fully on, and electrically saturates for the entire duration of the injector pulse width. This type of driver is better used with injectors having high resistance coils (12~16 Ohm). The advantage of this type of injector driver is that electrically generated heat is dissipated through the injector and not through the power transistor of the driver circuit. The circuitry is simplified compared to a peakand-hold type driver (which requires heat sinks to dissipate the electrical load).

Study The Responsory And Quantum Efficiency of Silicon P-N Junction by Using Pulse Plasma

In this work we have used plasma pulsed injector to prepare a P-N junction. Antimony was deposited on P-type silicon wafer and Indium was deposited on N-type silicon wafer. They were considered as thin film which was bombarded with accelerated hydrogen-ions from the pulsed plasma injector. Optical tests were conducted for the both junctions to evaluate their performance as optical detectors. These include the spectral response quantum efficiency and detectivity. They showed high response and efficiency for the long wavelength in the near IR region. It showed a relatively higher detectivity which increased with the number of discharges. For antimony and indium implanted samples we have noticed an increase in the response time of the detector with the number of discharges. These findings allow the possibility to use them in the near IR-detector and semiconductor lasers in the wavelength range 850-950nm as well as in the applications of optical communication systems. This work also revealed the possibility of using the pulsed plasma injection to modify the material surfaces as well as the ultering the semiconductor surfaces.

Measurement and verification of transient injection flow rate of high pressure natural gas pulse injector

A high-pressure natural gas direct injection engine can achieve lean combustion and diffusion combustion of natural gas, which can reduce the emission level and improve power performance. However, the transient gas injection rate of the injector directly affects the combustion rate. In order to optimize engine performance, it is essential to focus on the technology used to measure the transient injection rate. Therefore, in this study, a method is developed to measure the transient flow rate of a high-pressure natural gas pulse injector. First, experiments were conducted to locate the optimum position for sensor installation, thereby ensuring the quality of the signal. Subsequently, a mass flow meter and schlieren imaging method was used to verify the injection mass and injection start/end timing. Finally, the common working conditions of a certain type of injector are measured. Results indicated that the test error of the cycle injection mass and injection start/end timing did not exceed 4% and 2.1%, respectively. As the injector energizing time increased, the injection rate curve changed from triangle to trapezoid. As the injection pressure increased, the injection start delay time decreased and end delay time increased. Measurement of the main and post injection strategy indicates that the main injection has a significant impact on the injection mass and injection rate curve for post injection. When the interval between the two injections is short, the injection rate curves merge. This increases the injection duration. The total injection mass of the main injection and post injection mass is found to be significantly higher than the sum of the two independent injections.

Numerical simulation of heavy fuel oil atomization using a pulsed pressure-swirl injector

It is known that increasing the injection pressure reduces the breakup length and the droplet size. Adding pulses, on the other hand, helps to atomize the liquid into finer droplets, similar to air-assisted injectors but without altering the air-to-fuel concentration. To further reduce the droplet size and breakup length, a novel injector type, called “Pulsed Pressure-Swirl” (PPS), is introduced in this work, which is a combination of pressure-swirl and ultrasonic pulsed injectors. A pressure-swirl atomizer was designed and fabricated specifically for Mazut HFO (Heavy Fuel Oil). The droplet formation process and droplet size distribution have been studied experimentally (by shadowgraphy high speed imaging) and numerically (with the open-source Volume-of-Fluid code Gerris ). Changing liquid injection pressure effect on the spray angle and film thickness has been quantified. These simulations have been used to study the primary breakup process and quantify the droplet size distributions, using different injection pulse frequencies and pressures. The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length, especially when applying high pulse frequencies, with no significant changes in the spray angle.

“Dancing Droplets”: Partial Coalescence on Superhydrophobic Surfaces

Abstract Droplet coalescence has received significant attention due to its significant role in fluid mixing, microfluidics, coalescence-induced droplet jumping, and heat and mass transfer applications. Coalescence of droplets has been extensively investigated from the perspectives of hydrodynamics and energy transfer. However, the study of coalescence characteristics of size-mismatched droplets on superhydrophobic surfaces remains a challenge due to visualization difficulty, limited droplet size control, and poor droplet manipulation. Here, in order to study coalescence dynamics of droplets with arbitrary initial sizes, a droplet dispensing and visualization system was developed. To control the size of droplets, monodispersed droplets with radii of ≈20 μm were dispensed using a frequency-controlled piezoelectric pulse injector onto a superhydrophobic surface, enabling the target droplets to accumulate in volume and grow in radii. The coalescence process of droplets having radii of ≈270 and ≈780 μm was imaged at a magnification of ≈25X and capture rate of 13000 fps. Surprisingly instead of completely merging together, the size-mismatched droplets underwent partial coalescence with the development of an additional satellite droplet. Specifically, the smaller droplet gave 'birth' to a secondary satellite droplet upon coalescence with the larger primary droplet due to liquid-bridge pinch-off dynamics, after which the satellite droplet bounced off upon collision with the primary droplet due to the presence of an air cushion that blocked contact between the two droplets. Meanwhile, the primary droplet continued to oscillate while the bouncing satellite droplet returned to the surface and eventually bounced off (moving direction is identified with arrows). Our work not only presents a powerful platform capable of both controlling and visualizing droplet coalescence hydrodynamics, but also provides insights into the flow hydrodynamics of droplets undergoing partial coalescence.

Plasma Injectors for Quasi-Stationary High-Power Plasmodynamic Systems

Pulsed plasma injectors, that is, an “input ionization chamber” (IIC), an “anode ionization chamber” (AIC), and a high-pressure plasma injector, are described. Plasma injectors are designed to generate primary plasma in quasi-stationary high-power plasmodynamic systems, in particular, in the KSPU Kh-50 quasi-stationary high-current plasma accelerator. The results of studies of the main characteristics of plasma pulsed injectors are presented. The following charge currents in plasma were obtained: 23.5 kA for the AIC injector at a voltage of 3 kV, 90 kA for the IIC injector at a voltage of 0.65 kV, and 96 kA for the high-pressure plasma injector at a voltage of 3 kV.

Arc initiation in plasma installations

The paper is devoted to a research of electric arc ignition devices in plasma torch of alternating and direct current. High-voltage alternating current plasma is used as one of ignition devices. Its power is 5–10 kW, the plasma-forming gas flowrate is 2–5 g/s. The plasma flow with electron concentration of 1014–1016 cm−3 sufficient for main arc ignition is set in a zone of the minimum distance between the main electrodes of a plasma torch by injector operation. The second method uses a construction series of the direct current plasma torches. They were designed to transfer ac plasma torches with rail electrodes into a class of electrical installations with a supply voltage less than 1000 V. Their current-voltage characteristics and life tests are received. The cathode erosion is about 10−6 g/C, the anode erosion is 10−7 g/C. The pulse erosion injector is developed for an arc ignition in a direct current plasma torch. The pulsed injector is supplied from the capacitive storage.

A Novel Time Alignment Technique for Online PD Location in Covered Conductors

This letter presents a double-side measuring method for online partial-discharge (PD) detection and location in covered conductor (CC) lines. To synchronize both PD sampling units mounted on two separate sides, a novel time alignment technique is proposed and implemented using the combination of a pulse injector and a pulse detector. A laboratory experiment on a 10-kV CC line was conducted to verify the feasibility of this technique.

High power microwaves generation from intense relativistic electron beam using Kali-1000 pulse power system

Intense relativistic electron beam (IREB) is generated using Kali-1000 (Kilo Ampere Linear Injector) pulse power system, providing input electric power of 4 GW and stored energy of 1000 J. IREB is used for generating Non Ionizing (High Power Microwaves, HPM) and Ionizing (Flash X-rays) radiation. The present manuscript discusses generation of HPM by Kali-1000 system using an axial Virtual cathode oscillator. Kali-1000 pulse power system is a low impedance (~4 Ω) high voltage generator, consisting of Radial Tesla transformer to step up the voltage from 28 to 300 kV in 5 μs, which energizes the line, pulse discharged by a self triggered pressurized SF6 closing switch across a Relativistic Electron Beam (REB) diode load. The typical electron beam parameters are 300 kV, 15 kA and 100 ns with a current density of 3–4 hundreds of amperes per square centimeter. Experiments are carried with a REB diode consisting of graphite cathode and SS anode mesh. Measured pulse duration of HPM pulse (FWHM) varies from 70 to 110 ns on shot-to-shot basis. The major operating output frequencies have been measured to be 5.8 and 6.2 GHz within a range of 4.8–6.7 GHz using B-dot magnetic field sensor coupled to high frequency digital oscilloscope. Microwave output power from the virtual cathode oscillator has been measured to be 50 MW using double ridged waveguide horn antenna coupled with Schottky detector diode. The estimated beam to microwave power conversion efficiency is thereby found to be 1.1%. Particle-in-Cell (PIC) simulation has been performed for a set of Vircator experiments being driven by the Kali-1000 system. Experimentally measured cathode current, dominant output frequency, radiation pattern, etc., have been compared with simulation results and are in good agreement. The dominant emission mode from the virtual cathode oscillator is shown to be the TE01 mode based on the emission pattern of microwave induced air breakdown in this experiment.

Experimental research on the influence of the pulse injector control parameters on its flow rate

The paper presents the results of the impact of the control parameters on the fuel mass flow from the injector. The control parameters examined in the paper were: frequency and pulse width modulation of the modulated control signal (the second part of the injector control signal). The analysis covers 6 injector types of different design of the valve element and the coil. The experiments have shown that the frequency of the signal does not affect the injector performance, contrary to pulse modulation affecting the injector performance significantly.

SU-E-T-127: Detailed Analysis of TomoTherapy Quality Assurance (TQA) Before and After Dose Control System Upgrade (DCS) - 3 Year Collected Data

Purpose: Detailed data analysis, reliability comparison between the three years of collected data using TomoTherapy quality assurance (TQA) tool and software and standard manual QA test procedures. The analysis convers output, energy, magnetron arcs, noise, couch movement and overall performance of TomoTherapy unit. The analyses were performed on the data collected before and after dose control system (DCS) upgrade. Methods: Daily, weekly and monthly QAs were performed using two different methods, basic dosimetry, step wedge and solid water slabs using two ion chambers as specified by the manufacturer. Data from TQA software and standard QAs were analyzed. Results: The maximum variations between the TQA and standard QA were found not to exceed 2% before DCS upgrade and within 1% after DCS upgrade. Close agreement in case of magnetron replacement and magnetron voltage adjustment by about 1.0%. The amplitude of the arcs are smaller when DCS is installed. Conclusion: Based on the results, author believes TomoTherapy Quality Assurance (TQA) is a very useful tool available to the site physicist as well as to the TomoTherapy field service engineer. It is fast and provides in-depth information about, output, energy, magnetron performance, couch movement and many more. Hence it makes a very valuable tool. Since dose control system (DCS) adjusts injector current and pulse amplitude control (PAC) in order to maintain the output and dose rate variations, the arcs amplitudes are smaller compared to when DCS was not installed. It is a very handy tool when one is subjected to magnetron replacement or the prediction for the need of replacement and output adjustment as well. It is a reliable tool that provides valuable information about the performance of the machine and most of its component including couch movement, magnetron, noise, arcs, output, energy, jaws, linac and so on.

Use of an Accelerometer and a Microphone as Gas Detectors in the Online Quantitative Detection of Hydrogen Released from Ammonia Borane by Gas Chromatography

The use of an accelerometer as a gas detector in gas chromatography (GC) is described for the first time. A milli-whistle was connected to the outlet of the GC capillary. When the eluted and GC carrier gases pass through the capillary and milli-whistle, a sound is produced. After a fast Fourier transform (FFT), the sound wave generated from the milli-whistle is picked up by a microphone and the resulting vibration of the milli-whistle body can be recorded by an accelerometer. The release of hydrogen gas, as the result of thermal energy, from ammonia borane (NH3BH3), which has been suggested as a storage medium for hydrogen, was selected as the model sample. The findings show that the frequencies generated, either by sound or by the vibration from the whistle body, were identical. The concentration levels of the released hydrogen gas can be determined online, based on the frequency changes. Ammonia borane was placed in a brass reservoir, heated continually, and the released hydrogen gas was directly injected into the GC inlet at 0.5 min intervals, using a home-built electromagnetic pulse injector. The concentration of hydrogen for each injection can be calculated immediately. When the ammonia borane was encapsulated within a polycarbonate (PC) microtube array membrane, the temperature required for the release of hydrogen can be decreased, which would make such a material more convenient for use. The findings indicate that 1.0 mg of ammonia borane can produce hydrogen in the range of 1.0-1.25 mL, in the temperature range of 85-115 °C.

Real Time Monitoring of Diesel Engine Injector Waveforms for Accurate Fuel Metering and Control

This paper presents the development, experimentation, and validation of a reliable and robust system to monitor the injector pulse generated by an engine control module (ECM) which can easily be calibrated for different engine platforms and then feedback the corresponding fueling quantity to the real-time computer in a closed-loop controller in the loop (CIL) bench in order to achieve optimal fueling. This research utilizes field programmable gate arrays (FPGA) and direct memory access (DMA) transfer capability to achieve high speed data acquisition and delivery. This work is conducted in two stages: the first stage is to study the variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and inductor load cells, and over different operating conditions. Different thresholds have been used to find out the best start of injection (SOI) threshold and the end of injection (EOI) threshold that capture the injector “on-time” with best reliability and accuracy. Second stage involves development of a system that interprets the injector pulse into fueling quantity. The system can easily be calibrated for various platforms. Finally, the use of resulting correction table has been observed to capture the fueling quantity with highest accuracy.

Design of a Pulse Injector for DME Propellant

Recently, a pulsed plasma thruster (PPT), which has advantages such as smallness, lightweight and low power consumption, has attracted attention again for the application to small satellites. Liquid propellant like water or alcohol provides higher specific impulse in comparison with conventional Teflon propellant. Nevertheless, water and alcohol propellants have problems: higher freezing point or contamination to satellites by the exhaust gas. In this study, we propose to apply DME (Di-methyl ether) to the PPT's propellant. DME can be stored as liquid, and requires no pressurant because DME has a vapor pressure of 0.6 MPa at 298 K. DME would also be potentially usable as heat transfer media, coolant, working fluid of heat pipe etc. We have designed and tested a prototyped pulse injector supplying liquid DME to discharge channels of the PPTs. Experimental results showed that the pulse injector successfully injected liquefied DME of 1.16 mg/shot, which is equivalent to the mass shot of a high power class PPT. The shape of injected liquid was dependent on the duration of the gating-pulse applied to the injector; a group of droplets were provided with a 20 ms gating-pulse duration, and a single stream with 25 ms or longer gating-pulse duration.

Plans for Warm Dense Matter and IFE Target Experiments on NDCX-II

The Heavy Ion Fusion Science Virtual National Laboratory (HIFS-VNL) is currently developing design concepts for NDCX-II, the second phase of the Neutralized Drift Compression Experiment, which will use ion beams to explore Warm Dense Matter (WDM) and Inertial Fusion Energy (IFE) target hydrodynamics. The ion induction accelerator will consist of a new short pulse injector and induction cells from the decommissioned Advanced Test Accelerator (ATA) at Lawrence Livermore National Laboratory (LLNL). To fit within an existing building and to meet the energy and temporal requirements of various target experiments, an aggressive beam compression and acceleration schedule is planned. WDM physics and ion-driven direct drive hydrodynamics will initially be explored with 30 nC of lithium ions in experiments involving ion deposition, ablation, acceleration and stability of planar targets. Other ion sources which may deliver higher charge per bunch will be explored. A test stand has been built at Lawrence Berkeley National Laboratory (LBNL) to test refurbished ATA induction cells and pulsed power hardware for voltage holding and ability to produce various compression and acceleration waveforms. Another test stand is being used to develop and characterize lithium-doped aluminosilicate ion sources. The first experiments will include heating metallic targets to 10,000 K and hydrodynamics studies with cryogenic hydrogen targets.