Design and high-power testing of offline conditioning cavity for CiADS RFQ high-power coupler

To validate the design rationality of the power coupler for the RFQ cavity and minimize cavity contamination,we designed a low-loss offline conditioning cavity and conducted high-power testing.This offline cavity features two coupling ports and two tuners,operating at a frequency of 162.5 MHz with a tuning range of 3.2 MHz.Adjusting the installation angle of the coupling ring and the insertion depth of the tuner helps minimize cavity losses.We performed electromagnetic structural and multiphysics simulations,revealing a minimal theoretical power loss of 4.3%.However,when the cavity frequency varied by110 kHz,theoretical power losses increased to10%,necessitating constant tuner adjustments during conditioning.Multiphysics simulations indicated that increased cavity temperature did not affect frequency variation.Upon completion of the offline high-power conditioning platform,we measured the transmission performance,revealing a power loss of 6.3%,exceeding the theoretical calculation.Conditioning utilized efficient automatic range scanning and standing wave resonant methods.To fully condition the power coupler,a 15°phase difference between two standing wave points in the condition-ing system was necessary.Notably,the maximum continuous wave power surpassed 20 kW,exceeding the expected target.

The influence of AAR coupler features on estimation of in-train forces

Inadequate management of large in-train forces transferred through coupler systems of a railway train leads to running and structural failures of vehicles.Understanding these phenomena and their mitigation requires accurate estimation of relative motions and in-train forces between vehicle bodies.Previous numerical studies have ignored inertia of coupling elements and the impacts between couplers.Thus,existing models underestimate the additional dynamic variations in in-train forces.Detailed multi-body dynamic models of two AAR(Association of American Railroads)coupler systems used in passenger and freight trains are developed,incorporating coupler inertia and various slacks.Due to the modeling and simulation com-plexities involved in a full train model,with such details of coupler system,actual longitudinal train dynamics is not studied.A system comprising only two coupling units,inter-connecting two consecutive vehicles,is modeled.Considered system has been fixed at one end and an excitation force is applied at the other end,to mimic a relative force transmission through combined coupler system.Simulation results obtained from this representative system show that,noticeable influence in in-train forces are expected due to the combined effect of inertia of couplers and intermittent impacts between couplers in the slack regime.Maximum amplitude of longitudinal reaction force,transferred from draft gear housing to vehicle body,is expected to be significantly higher than that predicted using existing models of coupler system.It is also observed that the couplers and knuckles are subjected to significant longitudinal and lateral contact forces,due to the intermittent impacts between couplers.Thus,accurate estimation of draft gear reaction force and impact forces between couplers are essential to design vehicle and coupler components,respectively.

Influence of quick release valve on braking performance and coupler force of heavy haul train

We establish a simulation model based on the theory of air flow to analyze the accelerated release effect of the quick release valve inside the air brake control valve.In addition, the combined simulation system of train air brake system and longitudinal train dynamics is used to analyze how the parameters of the quick release valve in the 120/120–1 brake control valve affect the propagation characteristics of the train brake pipe pressure wave, the release action range of the accelerated brake, and the longitudinal coupler force for a 20,000-ton heavy haul train on the section of the Datong–Qinhuangdao Railway. The results show that the quick release valve can effectively accelerate the rising speed of the train brake pipe pressure during the initial release, as the accelerated release effect is evident before the train brake pipe pressure reaches582 k Pa. The quick release valve can effectively accelerate the release of the rear cars, reducing the longitudinal coupler force impact due to time delay of the release process. The quick release valve can effectively reduce the tensile coupler force in the train by as much as 20% in certain cases.

A phenomenological model of the fundamental power coupler for a superconducting resonator

In this study,a phenomenological model of the radio frequency(RF)behavior of a superconducting cavity fundamental power coupler is proposed by analyzing the simulation results of a transient beam-loading process in an extremely overcoupled superconducting cavity.Using this phenomenological model,the calculation of the transient reflected power from a superconducting cavity under beam loading can be mathematically simplified to algebraic operations without solving the differential equation governing the transient beam-loading process,while maintaining the calculation accuracy.Moreover,this phenomenological model can facilitate an intuitive understanding of the significant surge in the time evolution of reflected power from a superconducting cavity in certain beam-loading processes.The validity of this phenomenological model was carefully examined in various beam-loading processes and cavity conditions,and the method based on this phenomenological model was utilized in the transient RF analysis of the superconducting cavity system of the CAFe Linac,achieving satisfactory results.

Fast and perfect state transfer in superconducting circuit with tunable coupler

In quantum computation and quantum information processing, the manipulation and engineering of quantum systems to suit certain purposes are an ongoing task. One such example is quantum state transfer(QST), an essential requirement for both quantum communication and large-scale quantum computation. Here we engineer a chain of four superconducting qubits with tunable couplers to realize the perfect state transfer(PST) protocol originally proposed in quantum spin networks and successfully demonstrate the efficient transfer of an arbitrary single-qubit state from one end of the chain to the other,achieving a high fidelity of 0.986 in just 25 ns. This demonstrated QST is readily to extend to larger chain and multi-node configurations, thus serving as a desirable tool for scalable quantum information processing.

A rigid-flexible coupling finite element model of coupler for analyzing train instability behavior during collision

Rail vehicles generate huge longitudinal impact loads in collisions.If unreasonable matching exists between the compressive strength of the intermediate coupler and the structural strength of the car body,the risk of car body structure damage and train derailment will increase.Herein,a four-stage rigid-flexible coupling finite element model of the coupler is established considering the coupler buckling load.The influence of the coupler buckling load on the train longitudinal-vertical-hori-zontal buckling behavior was studied,and the mechanism of the train horizontal buckling instability in train collisions was revealed.Analysis results show that an intermediate coupler should be designed to ensure that the actual buckling load is less than the compressive load when the car body structure begins to deform plastically.The actual buckling load of the coupler and the asymmetry of the structural strength of the car body in the lateral direction are two important influencing factors for the lateral buckling of a train collision.If the strength of the two sides of the car body structure in the lateral direction is asymmetrical,the deformation on the weaker side will be larger,and the end of the car body will begin to deflect under the action of the coupler force,which in turn causes the train to undergo sawtooth buckling.

Design Optimization of Permanent Magnet Eddy Current Coupler Based on an Intelligence Algorithm

The permanent magnet eddy current coupler(PMEC)solves the problem of flexible connection and speed regulation between the motor and the load and is widely used in electrical transmission systems.It provides torque to the load and generates heat and losses,reducing its energy transfer efficiency.This issue has become an obstacle for PMEC to develop toward a higher power.This paper aims to improve the overall performance of PMEC through multi-objective optimization methods.Firstly,a PMEC modeling method based on the Levenberg-Marquardt back propagation(LMBP)neural network is proposed,aiming at the characteristics of the complex input-output relationship and the strong nonlinearity of PMEC.Then,a novel competition mechanism-based multi-objective particle swarm optimization algorithm(NCMOPSO)is proposed to find the optimal structural parameters of PMEC.Chaotic search and mutation strategies are used to improve the original algorithm,which improves the shortcomings of multi-objective particle swarm optimization(MOPSO),which is too fast to converge into a global optimum,and balances the convergence and diversity of the algorithm.In order to verify the superiority and applicability of the proposed algorithm,it is compared with several popular multi-objective optimization algorithms.Applying them to the optimization model of PMEC,the results show that the proposed algorithm has better comprehensive performance.Finally,a finite element simulation model is established using the optimal structural parameters obtained by the proposed algorithm to verify the optimization results.Compared with the prototype,the optimized PMEC has reduced eddy current losses by 1.7812 kW,increased output torque by 658.5 N·m,and decreased costs by 13%,improving energy transfer efficiency.

Coupler Loss Analysis of Magnetically Coupled Resonant Wireless Power Transfer System

The demand for electric vehicles has increased over the past few years.Wireless power transfer for electric vehicles provides more flexibility than traditional plug-in charging technology.Charging couplers are critical components in wireless power transfer systems.The thermal effect produced by the magnetic coupler in work will cause the temperature of the device to rise rapidly,affecting the work efficiency,transfer power,operation reliability,and service life.This paper modeled and analyzed each component's temperature distribution characteristics and thermal behavior.Firstly,the magnetic coupler's mutual inductance and magnetic circuit model are established,and the thermal model of the magnetic coupler analyzes the heat generation process.The thermal models of the coupler under three different magnetic core distributions are established,and the temperature rise of each component is obtained.The temperature rise of different parts of the coupler is verified by the temperature rise test structure of the experiment.

Design and Fabrication of Ultracompact 3-dB MMI Coupler in Silicon-on-Insulator

An ultracompact 3 dB coupler is designed and fabricated in silicon on insulator,based on 1×2 line tapered multimode interference (MMI) coupler.Comparing with the conventional straight MMI coupler,the device is ～40% shorter in length.The device exhibits uniformity of 1 3dB and excess loss of 2 5dB.

Stabilizing Mechanism and Running Behavior of Couplers on Heavy Haul Trains

Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.

Passively Mode Locked Diode-End-Pumped Nd∶YAG Laser with In_(0.25)Ga_(0.75)As as Output Coupler

A novel InGaAs(LT-In 0.25Ga 0.75As) absorber grown by metal organic chemical vapor deposition at low temperature is presented.Using it as well as an output coupler,passive mode locking,which produces pulses as short as several hundred picoseconds for diode-end-pumped Nd∶YAG laser at 1.06μm,is realized.The pulse frequency is 150MHz.

Full Wave Analysis of a Broad Wall Waveguide Slot Coupler

A rigorous analysis of a broad wall slot coupler composed of two crossed rectangular waveguides by using FDTD method is presented. Two types of slots, a longitudinal/transverse slot and a centered-inclined slot, are analyzed. Coupling slot characteristics are obtained, including scattering parameters and the resonant length for different waveguide dimensions and frequencies. The numerical results are all in good agreement with those by the method of moments. A coupler system with a short circuit port is also analyzed to help designing the slot array.

IEC711 coupler频响仿真

仿真耳(IEC711 coupler)广泛地应用于手提电话、耳机等的电声性能测量;介绍了利用有限元方法来获得IEC711 coupler的频响仿真,从而可以给出比等效线路图方法(LPM)更为真实的分析。

Analysis of longitudinal forces of coupler devices in emergency braking process for heavy haul trains

To reduce the longitudinal coupler forces of heavy haul trains and improve the running safety, the velocity method and New-mark method were used for the coupler simulation and numerical integration, and a numerical model on the longitudinal dynamics of heavy haul trains was established. Validation was performed against the experimental data. Using this model, the emergency braking process for a combined marshalling heavy haul train was investigated to obtain the distributions of the longitudinal compressive forces and strokes of coupler devices. Then, the influences of the initial braking velocity, the synchronization time of master and slave locomotives, the coupler stiffness and the vibrator mass on the longitudinal forces and strokes were analyzed. The results show that it should be avoided that the emergency braking starts at a low initial speed. Keeping synchronism between master locomotive and slave locomotives effectively helps to reduce the longitudinal forces. Reducing the coupler stiffness appropriately and adding rigid arm connections, the longitudinal vibration frequency can be brought down and the longitudinal forces will be decreased, which improves the running safety of heavy haul trains. All of these research results can provide a reference for the operation and development of heavy haul trains.

Experimental demonstration of single-mode fiber coupling using adaptive fiber coupler

Coupling plane wave into a single-mode fiber （SMF） with high and steady coupling efficiency is crucial for fiber- based free-space laser systems, where random angular jitters are the main influencing factors of fiber coupling. In this paper, we verified a new adaptive-optic device named adaptive fiber coupler （AFC） which could compensate angular jitters and improve the SMF coupling efficiency in some degree. Experiments of SMF coupling under the angular jitter situation using AFC have been achieved. Stochastic parallel gradient descent （SPGD） algorithm is employed as the control strategy, of which the iteration rate is 625 Hz. In closed loop, the coupling efficiency keeps above 65% when angular errors are below 80/3tad. The compensation bandwidth is 35 Hz at sine-jitter of 15 ~rad amplitude with average coupling efficiency of above 60%. Also, experiments with simulated turbulence have been studied. The average coupling efficiency increases from 31.97% in open loop to 61.33% in closed loop, and mean square error （MSE） of coupling efficiency drops from 7.43% to 1.75%.

Room-temperature test system for 162.5 MHz high-power couplers

Fundamental power couplers are crucial components for feeding radio frequency power to accelerating cavities. Couplers must be tested and conditioned on a room-temperature test stand to evaluate and potentially improve their performance before being installed in an accelerating cavity. A new test system has been designed and is under construction at the institute of modern physics.For this test system, multiple conditioning modes, including the pulse mode, CW mode, and amplitude-sweeping mode, have been embedded in the low-level radio frequency system of the test stand. All of these conditioning modes can be run manually or automatically. In addition, a novel test cavity is proposed and has been designed, which facilitates non-contact conditioning and a multi-purpose test stand.

High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre

A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator （SOI） nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46% and 25% at a wavelength of 1.55um are achieved by simulation and experiment, respectively. An optical 3 dB bandwidth of 45 mn from 1530 nm to 1575 nm is also obtained in experin, ent. Numerical calculation shows that a tolerance to fabrication error of 10 nm in etch depth is achievable. The measurement results indicate that the alignment error of 112 um results in less than 1 dB additional coupling loss.

High RF power tests of the first 1.3 GHz fundamental power coupler prototypes for the SHINE project

The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)project will use 6001.3 GHz fundamental power couplers,which are modified based on TTF-Ⅲ power couplers,for continuous-wave operation with input power up to approximately 7 kW.The first batch of 20 sets of 1.3 GHz coupler prototypes was fabricated from three domestic manufacturers for the SHINE project.To better characterize the radio frequency conditioning phenomena for validating the performance of power couplers,a room temperature test stand was designed,constructed,and commissioned for the SHINE 1.3 GHz power couplers.In addition,a horizontal test cryostat was built to test the 1.3 GHz superconducting cavities,fundamental power couplers,tuners,and other components as a set.The results of these tests indicate that the 1.3 GHz couplers are capable of handling up to 14 kW continuous waves.Herein,the main aspects of the radio frequency design and construction of the test stand,along with the test results of the high-power conditioning of the 1.3 GHz couplers,are described.

CMOS compatible highly efficient grating couplers with a stair-step blaze profile

A novel grating coupler with a stair-step blaze profile is proposed. The coupler is a CMOS process compatible device and can be used for light coupling in optical communication. The blaze profile can be optimized to obtain a high efficiency of 66.7% for the out-of-plane coupling at the centre wavelength of 1595 nm with a 1 dB bandwidth of 41 nm. Five key parameters of the stair-step blaze grating and their effects on the coupling are discussed for the application in L band telecommunication.

Integrated model optocouplers

Utilizing hybrid integration model.the integrated model optocouplers have successfully developed.The design,fabrication and characteristic parameters of the devices are presented.