Pump Energy Research Articles

5 kHz, 4.2mJ, 900 ps end-pumped Nd:YVO4 MOPA laser system.

A 5 kHz sub-nanosecond master oscillator power amplifier (MOPA) laser system was reported in this paper. The master oscillator was an electro-optically Q-switched Nd:YVO4 laser directly pumped at 879 nm, yielding a pulse energy of 520 µJ and a pulse width of 900 ps at 5 kHz. With two Nd:YVO4 amplifiers directly pumped at 914 nm, the pulse energy was further scaled up. Under the absorbed pump energy of 11.0 mJ, the pulse energy was amplified to 4.2 mJ, corresponding to a peak power of 4.7 MW. The optical-to-optical efficiency of the amplifiers reached 33.5%.

LED-pumped solid-state lasers with an improved optical pump system

An optical pump system for LED-pumped solid-state lasers is introduced to effectively couple the energy of pump sources to the active medium. The optical system is based on the coupling of optical rays from light-emitting diode sources to laser rod using high reflecting surfaces. Three different configurations with four, five, and six segments have been designed and their geometry is optimized with the 3D Monte-Carlo ray-tracing method to obtain the best performance. Moreover, a geometrical model is developed to describe the general behavior of the pump system. The pump systems have been fabricated and successfully applied to pump 3 mm diameter Ce:Nd:YAG laser rods with available white spectrum LEDs. The performance of the pump system is experimentally compared with the closed-coupled pumping configuration and white spectrum LEDs under equal pump energy and an identical optical resonator. The improved five and six segments pump systems when Epump>350mJ having more than 170 percent higher conversion efficiency than the closed-coupled configuration. Using six segments configuration and 500 mJ optical pump energy, the LED-pumped Ce:Nd:YAG laser oscillator produced laser spikes with a multi-mode beam structure and more than 700 μJ laser energy at 10 Hz repetition rate. A compact, high repetition rate >10 Hz, multi-milli joules LED-pumped solid-state lasers are possible by using the improved optical pump system and infrared LEDs.

Plasmonic distributed feedback lasing in an anodic aluminum oxide/silver/polymer hybrid membrane.

A hybrid membrane is employed as a high-order plasmonic distributed feedback (DFB) cavity to reduce the lasing threshold of polymer lasers. The hybrid membrane consists of an anodic aluminum oxide (AAO) membrane, a 25 nm thick silver layer and a free-standing polymer membrane. The AAO membrane is fabricated by a low-cost, single chemical etching method. Then, a layer of silver with a thickness of 25 nm is sputtered on the surface of the AAO. Subsequently, a polymer membrane is directly attached to the silver-plated AAO membrane, forming an AAO/silver/polymer hybrid membrane. Under optical pumping conditions, low-threshold, three-order DFB lasing is observed. The proposed laser device exhibited a dual-threshold characteristic because of the evolution from amplified spontaneous emission to DFB lasing. And a significant shift from omnidirectional emission to directional emission lasing can be observed while the pump energy density is beyond the second threshold. Furthermore, the plasmonic enhancement sourced from silver corrugation reveals important improvement effects to the DFB lasing of AAO/silver/polymer hybrid membrane for decreasing threshold, narrowing full width at half maximum (FWHM), and an increasing Q factor. This work may promote the design and production of low-cost and large-area high-order plasmonic DFB polymer lasers.

Analysis of a novel double-effect split mechanical vapor recompression systems for wastewater concentration

A novel double-effect split mechanical vapor recompression (MVR) system is proposed in this paper to reduce the system operation cost together with the technical requirements for the steam compressor. Theoretical models of the novel double-effect split MVR system together with the double-stage MVR system and double-effect downstream MVR system are established by the simulation software of Aspen Plus. Performances of the three systems for the concentration of calcium chloride solution with a mass flow rate of 1000 kg/h are simulated. For a better evaluation, analysis of the energy consumption, operation cost, compressor operating parameters and gained output ratio are carried out with the simulation results. It is concluded that an optimal steam ratio exists for the smallest compressor power consumption of the double-effect split MVR system which is 0.3 for the simulated conditions. The operation cost beneficial of the novel system increases with the rise of electricity price and final mass fraction of the solute. The maximal suction volume flow and pressure ratio of the steam compressor in the novel system are both the smallest among the three MVR systems. The pressure ratio ranges from 1.2 to 1.7 which can be easily realized by mature roots compressor or centrifugal compressor. Exergy efficiency of the novel system is also the highest. Development and application of heat pump or solar energy fresh steam generator can further enhance advantages of the novel system.

Capacity optimization of pumped storage hydropower and its impact on an integrated conventional hydropower plant operation

The energy sector contributes to around 60% of total greenhouse gas emissions. To limit climate change, the world is going through an energy transition to clean and affordable energy, therefore the share of variable renewable energy is increasing day by day. Power systems require significant flexibility to operate reliably. Pumped storage hydropower allows load balancing and stable integration of intermittent renewable energy in the electrical grid. All energy storage technologies, including pumped storage hydropower, are considered a net negative contributor to the grid since they draw more energy than they deliver. This paper uniquely investigates the true potential of pumped storage hydropower and its optimum operation along with existing conventional hydropower. It considers power, energy production, and utilization for both installations to determine an equilibrium condition for a net positive energy balance. The case study of the 300 MW Balakot conventional hydropower plant in Khyber Pakhtunkhwa, Pakistan indicates that the pumped storage hydropower sites, where additional water streams reach the upper storage reservoir, can reduce pumping energy consumption by up to 166 GWh/year. Accordingly, a pumped storage hydropower facility is proposed at Paras, Pakistan, modeled, and optimized in an integrated manner with the Balakot conventional hydropower plant for a net positive annual energy generation and profitability. The integrated power and energy modeling and capacity optimization of the hydropower complex highlight the importance of suitable site selection for pumped storage hydropower near existing conventional hydropower reservoirs. Value-added contribution of this configuration is that it can enhance annual energy generation from integrated conventional hydropower, reduce the upfront capital cost of the project by 10–15%, squeeze the project implementation schedule and result in a smaller carbon footprint to meet the ultimate objective of limiting climate change. Additionally, it unlocks huge untapped pumped storage hydropower potential besides existing conventional hydropower. Furthermore, the study guides the scientific and engineering organizations on optimum capacity utilization without impeding energy generation from conventional hydropower facilities.

Thermal lens effect induced in a Cr,Tm,Ho:YAG laser rod: A comparison between under lasing and non-lasing conditions

In this paper, transient thermal lensing effects in a typical flashlamp-pumped CTH:YAG laser crystal under lasing and non-lasing conditions are studied and compared in a low repetition-rate regime. It is shown that in the lasing regime (for pumping energies higher than 90J) the time-resolved behavior and the strength of the three mode thermal lenses of the rod are different from the non-lasing condition. According to this research, it can be referred that higher-order processes such as excited state absorption of both pump and laser radiation and energy transfer up-conversion may have a more significant contribution to the laser dynamics in the lasing regime. The analysis of the results also shows that the energy transfer between different manifolds in Cr3+, Tm3+, and Ho3+ ions may depend on coolant temperature.

An assessment of strategies for sustainability priority challenges in Jordan using a water–energy–food Nexus approach

This study aimed at supporting robust decision-making for planning and management of water–energy–food Nexus systems in the country of Jordan. Nexus priority challenges in Jordan were identified as (1) water scarcity, (2) agricultural productivity and water quality, and (3) shift to energy independence. We created a water–energy–food Nexus model that integrates three modelling frameworks: (1) the Water Evaluation and Planning system WEAP model to estimate water demands, supplies and allocation; (2) the MABIA model to estimate crop production, and, (3) a GIS-based energy modelling tool to estimate energy requirements of the water system. Through a set of scenario runs, results show how desalination is needed to address water scarcity, but it has to be coupled with low-carbon electricity generation in order to not exacerbate climate change. Improving water productivity in agriculture improves most of the studied dimensions across the water–energy–food security nexus; however, it does little for water scarcity at the municipal level. Reducing non-revenue water can have positive effects on municipal unmet demand and reduction of energy for pumping, but it does not improve agricultural water productivity and may have negative feedback effects on the Jordan Valleys aquifer levels. Energy efficiency can support energy-intensive projects, like desalination, by substantially reducing the load on the energy system, preventing increased emissions and achieving a more resilient water system. Finally, when all interventions are considered together all of the major drawbacks are reduced and the benefits augmented, producing a more holistic solution to the WEF Nexus challenges in Jordan.

Geometric energy transport and refrigeration with driven quantum dots

Geometric energy transport is of high interest both for spectroscopy of quantum devices and as a way to realize cyclic thermal machines at the nanoscale. Using a recently discovered dissipative symmetry, this work derives compact and insightful analytical expressions characterizing energy pumping with a slowly driven quantum dot subject to strong many-body interactions. Equipped with these results, the authors analyze the dot as a refrigerator or a heat pump, revealing a direct link between its efficiency and its well-known steady-state thermoelectric properties.

Plasma facing components with capillary porous system and liquid metal coolant flow

Liquid metal can create a renewable protective surface on plasma facing components (PFC), with an additional advantage of deuterium pumping and the prospect of tritium extraction if liquid lithium (LL) is used and maintained below 450 °C, the temperature above which LL vapor pressure begins to contaminate the plasma. LM can also be utilized as an efficient coolant, driven by the Lorentz force created with the help of the magnetic field in fusion devices. Capillary porous systems can serve as a conduit of LM and simultaneously provide stabilization of the LM flow, protecting against spills into the plasma. Recently, a combination of a fast-flowing LM cooling system with a porous plasma facing wall (CPSF) was investigated [A. Khodak and R. Maingi, Nucl. Mater. Energy 26, 100935 (2021)]. The system takes an advantage of a magnetohydrodynamics velocity profile as well as attractive LM properties to promote efficient heat transfer from the plasma to the LL at low pumping energy cost, relative to the incident heat flux on the PFC. In the case of a disruption leading to excessive heat flux from the plasma to the LM PFCs, LL evaporation can stabilize the PFC surface temperature, due to high evaporation heat and apparent vapor shielding. The proposed CPSF was optimized analytically for the conditions of a fusion nuclear science facility [Kessel et al., Fusion Sci. Technol. 75, 886 (2019)]: 10 T toroidal field and 10 MW/m2 peak incident heat flux. Computational fluid dynamics analysis confirmed that a CPSF system with 2.5 mm square channels can pump enough LL so that no additional coolant is needed.

The enhancement and regulation of lasing in dye-doped multi-layer polymer film systems

As a new research hotspot in nano-materials and nano-structures, photoluminescence is widely used in medical imaging, biosensors, integrated devices and other fields because of its excellent optical performance and good stability. The design and fabrication of these nanostructures are expensive and complex, meanwhile, the influence of film structure change on lasing characteristics has not been systematically summarized. Thus, there are still challenges to realizing lasing regulation by using a multilayer film system. In this study, a dye-doped multilayer system was prepared by a convenient spin-coating method on polyethylene glycol terephthalate (PET) film. The effects of sandwich-like film and Au nanoparticles on the lasing characteristics were studied. The results show that the sandwich-like film can form a mirror symmetry plane and increase the photon scattering frequency. Furthermore, the band-gap edge effect can effectively improve the photon gain, enhancing the optical feedback and realizing band-edge lasing. The lasing intensity in the sandwich-like film is nearly 30% higher than that of the bilayer film system at the same pump energy. By adding Au nanoparticles as scatterers, the local electromagnetic field can be enhanced because of the surface plasmon resonance, improving the transition rate of dye molecules. Meanwhile, the photon scattering frequency among the scattering cross-section can also be increased, increasing the interaction between photons and dye. The lasing intensity can be enhanced by 160% at the same pump energy because of the interaction between the plasmon resonance effect and the scattering effect. The fabrication method in this study is convenient and easy to implement, which is conducive to improving the lasing intensity and provides an effective technical way for the realization of a modulated random laser.

Experimental investigation of the Electrical Submersible Pump's energy consumption under unstable and stable oil/water emulsions: A catastrophic phase inversion analysis

The presence of water in crude oil exploitation by the Electrical Submersible Pump (ESP) systems may cause several problems in energy consumption and operational instabilities due to emulsion formation. Indigenous surfactants in crude oil also contribute to emulsion stabilization, which can exacerbate these problems. In this paper will be experimentally investigated the influence of the emulsion stability on ESP energy consumption and operational instabilities through an 8-stage ESP operating with unstable and stable emulsions, with and without a demulsifier. The experimental tests were performed for one oil viscosity, a constant total flow rate, and two ESP rotational speeds. Initially, the ESP relative dimensionless power (RDP) was analyzed along with the emulsion system and the droplet size distribution (DSD). An interesting difference regarding the presence of surfactants was observed experimentally in the RDP and phase inversion points. The relationship among the ESP dimensionless power, torque, and electrical current with maximum droplet size allowed to conclude that these parameters can be related to the start of the coalescence process, i. e, able to predict the catastrophic phase inversion (CPI) point.

On-chip mid-IR octave-tunable Raman soliton laser.

Photonic chip-based continuously tunable lasers are widely recognized as an indispensable component for photonic integrated circuits (PICs). Specifically, mid-infrared (mid-IR) laser sources are of paramount importance in applications such as photonic sensing and spectroscopy. In this article, we theoretically investigate the propagation dynamics of mid-IR Raman soliton in Ge28Sb12Se60 chalcogenide glass waveguide. By carefully engineer the waveguide dispersion and nonlinear interaction, we propose a suspended chalcogenide glass waveguide device that allows an octave-tuning, from 1.96 µm to 3.98 µm, Raman soliton source. The threshold pump energy is in the low pico-Joule range. Our result provides a solution to continuously tunable on-chip mid-IR ultrafast laser sources.

The effect of various irrigation technologies and strategies on water resources management

Today, the uncontrolled abstraction of surface water and groundwater resources has created adverse consequences, which include: extinction of living organisms, land subsidence, salinity of coastal aquifers, increased pumping energy. Therefore, the need to manage available water resources is felt more than ever. Among the various water uses (agriculture, drinking, and industry), agriculture accounts for the bulk of water consumption. Due to the climate change and the growing population, determining the appropriate strategy and technology for irrigation is necessary. In the current study, a simulation model is used to numerically simulate the dynamics of daily soil moisture during the potato crop growing season and to estimate crop production and economic benefits. For climatic data, daily observations of a meteorological station have been used. Results and analyses have been presented for all cases of micro and traditional irrigation methods and agricultural management strategies of non-stress irrigation, low irrigation, and rainfed cultivation. The results showed that in the non-stress irrigation method, crop production and net profit are almost equal in both traditional and micro methods. In the low irrigation method, microtechnology has made crop production and net profit 1.75 times more than traditional technology, which indicates the impact of irrigation technology on crop production.

Electron attachment dynamics following UV excitation of iodide-2-thiouracil complexes

The dynamics of low energy electron attachment to the thio-substituted uracil analog 2-thiouracil are investigated using time-resolved photoelectron spectroscopy (TRPES) of iodide-2-thiouracil (I-·2TU) binary clusters. In these experiments, the anions are excited at pump energies of 4.16 and 4.73eV, and the ensuing dynamics are probed by photodetachment at 1.59 and 3.18eV. Upon excitation near the vertical detachment energy (4.16eV), dipole bound (DB) and valence bound (VB) anion signals appear almost instantaneously, and the DB state of the 2TU anion undergoes an ultrafast decay (∼50fs). At 4.73eV, there is no evidence for a DB state, but features attributed to two VB states are seen. The transient negative ions formed by photoexcitation decay by autodetachment and I- fragmentation. The I- dissociation rates and their dependence on excitation energy agree reasonably well with the Rice-Ramsperger-Kassel-Marcus calculations. Notable differences with respect to TRPES of the related iodide-uracil anion are observed and discussed.

A nonlinear metamaterial plate for suppressing vibration and sound radiation

Nonlinear acoustic metamaterials (NAMs) exhibit extraordinary properties for low-frequency and broadband vibration mitigation. Despite the increasing attention received, exotic properties and the physical mechanisms underpinning NAM-enabled functionalities have not been fully understood. Moreover, investigations on the sound radiation of NAM structures have not been reported. Here we systematically investigate the vibration of a NAM plate and its sound radiation using experimental and theoretical methods. We experimentally demonstrate that the NAM plate can entail significant vibration and sound radiation reduction in an ultra- low and broad frequency band, typically from 20 to 1800 Hz, without any artificial damping element. This is attributed to the nonlinear coupling among multiple local resonances, and the nonlinear collision-friction damping. This understanding allows the proposal of two design strategies to achieve ultra- low and broadband vibration and sound radiation suppression with NAMs. Moreover, we clarify the mechanisms governing the ultra- low and broadband features, including bandgaps, output saturation of nonlinear resonances, efficient energy pumping due to high-order harmonics and chaos, and modulation of nonlinear resonance modal amplitudes and shapes. These mechanisms and diverse wave behaviors are inter-related and occur concurrently. The reported study provides answers to several key questions of paramount importance in designs, mechanics and applications of nonlinear metamaterials.

Cascaded Amplification and Manipulation of Terahertz Emission by Flexible Spintronic Heterostructures

AbstractSpintronic heterostructures consisting of ferromagnetic (FM) and nonmagnetic (NM) have become increasingly important devices for terahertz (THz) pulse generation, named as spintronic THz emitter (STE). The recycling of the laser pump energy is known to have a key impact on further improvement of the THz emission. Here, an efficient and practical approach to enhance and manipulate THz generation based on a cascaded Pt/CoFe/Ta trilayer fabricated on a flexible polyethylene terephthalate (PET) substrate is shown. Considering the refractive index n of PET is ≈1.61 at 1.55 eV and ≈1.75 at THz frequencies, it is anticipated that the femtosecond (fs) laser pulse propagates with a similar group velocity as the generated THz pulse. Therefore, the cascaded design enables all THz emission from each PET/STE propagating almost in‐phase and yields a 1.55 times amplification compared to a single PET/STE. Two proof‐of‐concept demonstrations are experimentally presented. First one, a metasurface can be assembled with the cascaded PET/STE to manipulate the THz signal. Second one, the cascaded PET/STE is used to perform a spectroscopic measurement of riboflavin. These demonstrations highlight the potential of flexible PET/STE for building blocks of advanced functionalities, such as compact THz emitters, THz spectroscopic, and imaging systems.

A novel strategy utilizing local fracture networks to enhance CBHE heat extraction performance: A case study of the Songyuan geothermal field in China

To overcome the restrictions of the limited heat exchange area of the traditional coaxial borehole heat exchanger (CBHE), an enhanced CBHE is proposed. This strategy significantly improves the heat exchange area by constructing local hydraulic fractures for the low-temperature fluid to pass through. Herein, a thermo-hydraulic coupling model based on the Songyuan geothermal field was established to address the heat extraction performance of 15 fracture networks in the enhanced CBHE. The effects of engineering parameters on the thermal benefits are discussed. Results suggest that the proposed strategy improved the accumulated heat energy by more than 6.5 times. Although the lifetime and production temperature of the system declines with the fracture area growth, the net heat energy is improved due to significant reductions in pump energy consumption. A critical feature of this strategy is configuring the hydraulic fractures connecting the well section rather than simply expanding the stimulation volume. The enhanced CBHE is most sensitive to the injection flow, which controls the response process of the thermal benefits to other engineering parameters. Moreover, fracture permeability plays a dual role in regulating the positive and negative correlations of the net heat energy. This work provides substantial insight into CBHE technology upgrading.

Performance and optimisation of a novel phase change thermal storage device

To apply phase-change thermal storage in heat-pump systems, a low heat-transfer temperature difference is required. The typical temperature material requirements for phase change limit the application of its thermal storage in heat pump energy supply systems. This study introduces a novel phase-change thermal storage device suitable for a renewable energy supply system composed of multichannel flat tubes and closed rectangular fins. Performance experiments and optimisation of the connection geometry of the thermal storage units under low heat-transfer temperature differences were carried out. When the inlet temperature of the heat transfer fluid was 55 °C (the melting point of the phase change material is 50 °C), the energy storage density and gravimetric specific power can reach 175.16 kJ/kg and 27.93 W/kg respectively, which has obvious advantages compared to relevant devices in the literature. A dimensionless energy-efficiency ratio was used to optimise the device. It was shown that the series type can significantly increase pressure loss while improving heat storage performance, and optimising the structure and operation design parameters of parallel components is more beneficial in terms of device performance improvement. The optimal operating flow corresponding to different heights of the novel thermal storage unit in parallel was provided, thus laying a theoretical foundation for practical applications.

Impact of thermosiphoning on long-term behavior of closed-loop deep geothermal systems for sustainable energy exploitation

Circulation of working fluid in closed geothermal loops is an alternative environmentally friendly approach to harvest subsurface energy compared to open hole geothermal doublet systems. However, the rapid decline of production temperature, low generated thermal power, and difficulties in deepening the system are major limitations. Herein, synthetic studies are presented to investigate the system's performance and improve its longevity for better use of this clean baseload power. The investigations are conducted by implementing appropriate equations of state to model state-of-the-art thermal and hydraulics processes in wellbores and considering various geometrical configurations to adopt proper design strategies. They provide insight for maximizing the generated thermal power, decreasing pumping energy, and avoiding production temperature drawdown. The results indicate that a stable thermal condition could be reached in which not only the temperature breakthrough is avoidable, but also the generated thermal power and production temperature continuously enhance over the project lifetime of one century. Analysis of the thermosiphon effect in the designed systems revealed that even with the pressure loss of 900 kPa at surface installations, the triggered natural flow rate is larger than 11 L/s. This thermosiphon flow rate yields the thermal power production of 2 MW and Cumulative extracted energy of 15 PJ over the project lifetime of 100 years. Restriction of this flow rate to 5 L/s leads to an average extraction temperature of 80 °C. It is also found that a change in the subsurface temperature gradient does not affect the optimal 2 km isolation length of the production well.

Optimization Design of Multi-Factor Combination for Power Generation from an Enhanced Geothermal System by Sensitivity Analysis and Orthogonal Test at Qiabuqia Geothermal Area

In order to explore the optimal mining strategy of a fractured Enhanced Geothermal System (EGS) reservoir, we numerically investigated the influence of seven factors on heat production and conducted an optimization analysis of a multi-factor and multi-level combination by an orthogonal test based on the geological data at the Qiabuqia geothermal field. Seven factors were considered, including five reservoir factors (fracture spacing, fracture permeability, fracture permeability anisotropy, matrix permeability, and heat conductivity) and two operation factors (injected section length and injection rate). The results show that injection rate and fracture permeability have the greatest influence on production performance. Different factor combinations have a great influence on the productivity. The multi-factor and multi-level combination optimization is needed, and the optimization scheme of the EGS can be achieved through the orthogonal test and range analysis. The order of influence degree on the power generation is injection rate > fracture permeability > fracture permeability anisotropy > injected section length > matrix permeability > fracture spacing > heat conductivity. The order of influence degree on the coefficient of performance of the EGS is fracture permeability > injection rate > injected section length > fracture permeability anisotropy > matrix permeability > fracture spacing > heat conductivity. For reservoir stimulation, the stratum with dense natural fractures should be selected as the target EGS reservoir. It is not advisable to acidify the EGS reservoir too much to widen the apertures of the natural fractures. Fracture permeability anisotropy will increase pump energy consumption, but this adverse effect can be greatly reduced if the other parameters are well matched. Matrix permeability and heat conductivity may not be used as indicators in selecting a target reservoir. For project operation, the injected section length should be as long as possible. The injection rate plays a major role in all factors. Special attention should be paid to the value of the injection rate, which should not be too large. The appropriate injection temperature should be determined in accordance with the water source condition and the engineering requirement. If a commercial rate (100 kg/s) is to be obtained, the permeability of the reservoir fracture network needs to be stimulated to be higher. Meanwhile, in order to ensure that the production temperature is both high and stable, it is necessary to further increase the volume of the EGS reservoir.