bluuebunny/crossref_metadata_2025 huggingface dataset:
Connection of difficult-to-form sheets by clinching process: A review
Authors: Xu Fan , Wang Huixiong , Gao Ming , Liu Hong , Xu Lijiao
Published: April 2022

The clinching technology attracted increasing attention in recent years, but its application might be restricted due to the growing employment of materials that are difficult to join and hybrid structures involving different mechanical performance materials. Traditional clinching technology has limitations of strain rate sensitivity, ductility and damage fracture when applied to materials with high strength, low strain-to-failure and low plasticity. However, the ductility and formability of the material represent a limitation for the clinching process. The present study explored some concepts of clinching, such as hole, friction-assisted, laser-assisted, electro-hydraulic, electromagnetically assisted and hot assisted clinching, for the difficult-to-form sheets. The paper includes the description of the deformation mechanism of clinched joints and the analysis of clinched joint performance and applicability.
Chiral metasurface design with highly efficient and controllable asymmetric transmission and perfect polarization conversion of linearly polarized electromagnetic waves in the THz range
Authors: Luo Yue , Qiu Kepeng , Moumni Ziad , Zhang Weihong , Zhu Jihong , Zhang Fuli
Published: April 2022

The influences of metasurfaces on the propagation of electromagnetic waves generate several important effects, such as asymmetric transmission and polarization conversion, that are highly useful in optical and microwave communication applications. However, easy method for dynamically controlling the asymmetric transmission of linearly polarized waves with perfect polarization conversion and high efficiency over a wide band in the THz range remain poorly developed. Our work addresses this issue by designing a novel metasurface structure consisting of two outer orthogonal gratings and a central lattice with an optimized chiral graphene monolayer distribution topology sandwiched between dielectric substrates. The frequency-dependent performance of the proposed metasurface is evaluated according to analyses of the asymmetric transmission coefficient, polarization conversion rate, total transmission coefficient, polarization rotation angle, ellipticity, and chirality parameter based on the results of simulations. The results demonstrate that the proposed structure provides highly efficient asymmetric transmission of linearly polarized waves and perfect polarization conversion in the high frequency range from 0.1 to 3.0 THz. The asymmetric transmission and the polarization conversion of the structure are dynamically controllable by changing the Fermi energy of graphene from 0 eV to 1 eV. The results of the analysis reveal that the observed dynamic controllability is a function of the interrelation between the special configuration of the chiral metasurface structure and the special properties of graphene.
Experimental study on the dynamics and parameters of nanosecond laser-induced aluminum plasma
Authors: Xu Yongfeng , Yang Liang , Zhou Dongjian , Liu Benkang , Li Qingwei , Shi Wenbo , Jin Yuqi
Published: April 2022

In this paper, impulse measurement, spectral diagnostics, temporal evolution images and target ablation are employed to investigate the dynamic behaviors and parameters of Nd:YAG nanosecond laser-induced aluminum plasma at different pressures and laser fluences. The impulses and coupling coefficients generated by laser ablation increase firstly and then reduce with the decrease in pressure for the laser fluences of 17.22 J cm−2 and 20.94 J cm−2, but they only drop at 0.5 Torr for a laser fluence of 6.19 J cm−2. The fast exposure images captured by the high-speed camera and ICCD show that the plasma plumes present the separation at atmospheric pressure and expansion near vacuum, but last longer time at pressures of 150 Torr and 22 Torr. The duration and dynamic property of plasma are responsible for the impulse, as well as are mainly dependent on the characteristics of plasma parameters. Therefore, the electron density and electron temperature are obtained by Stark broadening method and Boltzmann plot, respectively. The change in the electron density is proportional to pressure and laser fluence. The variation trend of the crater depth and ablative mass with pressure is opposite to that of the electron density, which is ascribed to the plasma shielding effect caused by the inverse bremsstrahlung absorption mechanism. Besides, the electron temperature varies inversely with pressure in the detection range due to various recombination processes. This study provides an insight for clarifying the energy conversion mechanism and improving the laser propulsion performance.
Weak dipole moments of heavy fermions with flavor violation induced by Z′ gauge bosons
Authors: Montaño-Domínguez J , Quezadas-Vivian B , Ramírez-Zavaleta F , Tututi E S
Published: April 2022

A calculation of weak dipole moments of charged fermions of the standard model at the one-loop level, in the context of a general effective extended neutral current model with flavor changing

Z

′

f

i

f

¯

j

vertices, is presented. We give numerical predictions for the anomalous weak magnetic dipole moment

a

f
i

w

, and the weak electric dipole moment (WEDM)

d

f

i

w

, for the τ lepton and t quark. For several Z′ gauge bosons considered, we find that, for the τ lepton, the best prediction for the real part of

a

τ

w

is of the order of 10−9, while the imaginary part is four orders of magnitude below. The highest value for the WEDM,

d

τ

w

, corresponds to 10−26
e cm, for its real part, and the imaginary part is three orders of magnitude below. Moreover, we found for the top quark, that the best prediction for the real part of

a

t

w

is of the order of 10−7 and its imaginary part is of the order of 10−11. We also found that

d

t

w

is of the order of 10−26
e cm for its real part, and its imaginary part can be as high as 10−31
e cm.
Extraction of different temperatures and kinetic freeze-out volume in high energy collisions
Authors: Waqas M , Peng G X , Ajaz M , Haj Ismail A , Wazir Z , Li Li-Li
Published: April 2022

We analyze the transverse momentum (p
T) spectra, 1/N
ev[(1/2πp
T)d2
N/dydp
T], of kaon, proton, deuteron and triton in different centrality events in gold–gold (Au–Au) collisions at relativistic heavy ion collisions (RHICs) by Hagedorn thermal model and extracted the excitation function of effective temperature, kinetic freeze-out volume, initial temperature and kinetic freeze-out temperature. We perceived that the effective temperature, initial temperature and kinetic freeze-out temperature sharply increases from 7.7 GeV to 14.5 GeV and then remain static from 14.5–39 GeV, and this consistency may disclose that the onset energy of the phase transition of partial deconfinement and the whole deconfinement are 14.5 and 39 GeV, respectively. The kinetic freeze-out volume and mean transverse momentum grows with the rise of collision energy. Furthermore, the different extracted temperatures are observed in the order of time evolution of the interacting system, and they (as well as kinetic freeze-out volume) have an increasing trend from peripheral to central collisions. We also observed the mass dependence of the effective temperature and kinetic freeze-out volume where former increases while the later decreases for heavier particles, which indicates the early freeze-out of the heavier particles.
Towards an ecological modelling approach for assessing ionizing radiation impact on wildlife populations
Authors: Vives i Batlle J , Biermans G , Copplestone D , Kryshev A , Melintescu A , Mothersill C , Sazykina T , Seymour C , Smith K , Wood M D
Published: April 2022

The emphasis of the international system of radiological protection of the environment is to protect populations of flora and fauna. Throughout the MODARIA programmes, the United Nations’ International Atomic Energy Agency (IAEA) has facilitated knowledge sharing, data gathering and model development on the effect of radiation on wildlife. We present a summary of the achievements of MODARIA I and II on wildlife dose effect modelling, extending to a new sensitivity analysis and model development to incorporate other stressors. We reviewed evidence on historical doses and transgenerational effects on wildlife from radioactively contaminated areas. We also evaluated chemical population modelling approaches, discussing similarities and differences between chemical and radiological impact assessment in wildlife. We developed population modelling methodologies by sourcing life history and radiosensitivity data and evaluating the available models, leading to the formulation of an ecosystem-based mathematical approach. This resulted in an ecologically relevant conceptual population model, which we used to produce advice on the evaluation of risk criteria used in the radiological protection of the environment and a proposed modelling extension for chemicals. This work seeks to inform stakeholder dialogue on factors influencing wildlife population responses to radiation, including discussions on the ecological relevance of current environmental protection criteria. The area of assessment of radiation effects in wildlife is still developing with underlying data and models continuing to be improved. IAEA’s ongoing support to facilitate the sharing of new knowledge, models and approaches to Member States is highlighted, and we give suggestions for future developments in this regard.
The optimal beam-loading in two-bunch nonlinear plasma wakefield accelerators
Authors: Wang Xiaoning , Gao Jie , Su Qianqian , Wang Jia , Li Dazhang , Zeng Ming , Lu Wei , Mori Warren B , Joshi Chan , An Weiming
Published: April 2022

Due to the highly nonlinear nature of the beam-loading, it is currently not possible to analytically determine the beam parameters needed in a two-bunch plasma wakefield accelerator for maintaining a low energy spread. Therefore in this paper, by using the Broyden–Fletcher–Goldfarb–Shanno algorithm for the parameter scanning with the code QuickPIC and the polynomial regression together with k-fold cross-validation method, we obtain two fitting formulas for calculating the parameters of tri-Gaussian electron beams when minimizing the energy spread based on the beam-loading effect in a nonlinear plasma wakefield accelerator. One formula allows the optimization of the normalized charge per unit length of a trailing beam to achieve the minimal energy spread, i.e. the optimal beam-loading. The other one directly gives the transformer ratio when the trailing beam achieves the optimal beam-loading. A simple scaling law for charges of drive beams and trailing beams is obtained from the fitting formula, which indicates that the optimal beam-loading is always achieved for a given charge ratio of the two beams when the length and separation of two beams and the plasma density are fixed. The formulas can also help obtain the optimal plasma densities for the maximum accelerated charge and the maximum acceleration efficiency under the optimal beam-loading respectively. These two fitting formulas will significantly enhance the efficiency for designing and optimizing a two-bunch plasma wakefield acceleration stage.
A comparative analysis and an optimized structure of vertical GaN floating gate trench MOSFET for high-frequency FOM
Authors: Jaiswal Nilesh Kumar , Ramakrishnan V N
Published: April 2022

A vertical GaN floating gate trench MOSFET (FG-MOSFET) device structure has been optimized to obtain an enhanced high-frequency figure of merit (HF-FOM) than the conventional SGT- and TG-MOSFET. The floating gate (FG) electrode helps to reduce the surface electric field and binges in the middle of the drift layer. Using TCAD simulation, we demonstrate that with proper design of trench depth, drift doping, and field plate oxide thickness, the corresponding electric-field distribution for FG-MOSFET can be reduced to 2.3 MV cm−1. The proposed device has been designed for 600 V blocking voltage capability and with a specific on-resistance (

R

on

) as low as 0.73 mΩ cm2 due to the higher drift doping concentration. The HF-FOM (

Q

GD

×

R

on

) of FG-MOSFET shows a lower by two times and four times compared to SGT- and TG-MOSFET, due to FP oxide. Our results show that the FG-MOSFET device produces 15% and 47% reductions in the switching energy losses when compared with the similar current rated SGT- and TG-MOSFET devices, respectively.
Information theoretic limits of learning a sparse rule
Authors: Luneau Clément , Macris Nicolas , Barbier Jean
Published: April 2022

We consider generalized linear models in regimes where the number of nonzero components of the signal and accessible data points are sublinear with respect to the size of the signal. We prove a variational formula for the asymptotic mutual information per sample when the system size grows to infinity. This result allows us to derive an expression for the minimum mean-square error (MMSE) of the Bayesian estimator when the signal entries have a discrete distribution with finite support. We find that, for such signals and suitable vanishing scalings of the sparsity and sampling rate, the MMSE is nonincreasing piecewise constant. In specific instances the MMSE even displays an all-or-nothing phase transition, that is, the MMSE sharply jumps from its maximum value to zero at a critical sampling rate. The all-or-nothing phenomenon has previously been shown to occur in high-dimensional linear regression. Our analysis goes beyond the linear case and applies to learning the weights of a perceptron with general activation function in a teacher-student scenario. In particular, we discuss an all-or-nothing phenomenon for the generalization error with a sublinear set of training examples.
Strength, thermal resistance and electrical conductivity of aluminum-based composite wire
Authors: Yu Murashkin M , Sadykov D I , Mavlyutov A M , Magomedova D K , Kazykhanov V U
Published: April 2022

In this work, we demonstrate the possibility of producing a composite high strength and thermal resistant Al-based wire with ultrafine-grained (UFG) structure. Such composite wire consists of two aluminum alloys. Its clad is made of Al-1.17Mg-0.35Zr (wt.%) alloy, and the core is of Al-0.4Zr (wt.%). The specimens of Al alloys separately and as parts of a composite wire were subjected to thermomechanical treatment (TMT) that included annealing at 400°C, equal-channel angular pressing via “Conform” scheme (ECAP-C) and cold drawing (CD). The ratio between the core and clad materials in the composite wire was determined experimentally as well as calculated from the rule of mixtures (additivity). It has been shown that, an ultimate tensile strength over 360 MPa and a long-term operation temperature of 150°C can be achieved in a composite wire at a rational ratio between the chosen aluminum alloys with the UFG structures. Such combination of strength and thermal resistance is accompanied with an electrical conductivity of no less than 50% IACS in a composite wire.
On the wave motion on the surface of a viscous stratified liquid
Authors: Chashechkin Yu , Ochirov A
Published: April 2022

The problem of propagation of gravitational waves along the surface of a semi-infinite viscous stratified liquid is considered. Wave and related non-wave components of the flow are detected. The dispersion relations of the detected types of motion are investigated.
Mathematical modeling of temperature stresses in a nonlocal thermoviscoelastic continuous medium
Authors: Kuvyrkin G N , Yu Savelyeva I , Kuvshinnikova D A
Published: April 2022

The improvement of the properties of structural and functional materials is associated with the synthesis of materials from structures with limiting values of properties (for example, extremely strong, refractory, thermostable, etc.). Such materials have an inhomogeneous structure, justified by the technological features of their preparation. In recent years, such materials have come to be called “structure–sensitive,” and the study of their thermomechanical characteristics has become possible within the framework of generalized mechanics of a continuous medium. Mathematical models describing such materials belong to the class of non-local models proposed by A. K. Ehringen. Now, there are few works on the use of nonlocal viscoelasticity, while many materials exhibit viscoelastic properties, even nonlocal viscoelastic properties, for example, solid propellants, composite materials, etc. The paper considers a mathematical model of a nonlocal thermoviscoelastic continuous medium. Using the finite element method, the temperature stress distributions are found for high-intensity pulsed heating of a nonlocal half-space.
Experimental study of the characteristics of heptane combustion in a high-speed steam jet
Authors: Sadkin I S , Kopyev E P , Mukhina M A , Anufriev I S
Published: April 2022

This paper is devoted to the experimental study of the characteristics of heptane combustion in a high-speed superheated steam jet. The completeness of the combustion under steam gasification conditions and the gas composition of the heptane combustion products cooled to room temperature were determined. The averaged temperature of the flame was measured. It is shown that the presence of superheated steam ensures high combustion efficiency and reduces emissions of nitrogen oxides in comparison with a heated air combustion. It is also shown that the organization of liquid fuel combustion in a high-speed steam jet ensures effective burning of fuel in the absence of nozzles and swirlers.
Integrated use of coal and coal-containing waste
Authors: Golubev V A , Platov I V
Published: April 2022

The current aggravation of such serious challenges as minimization of harmful emissions and suppression of the carbon footprint can be largely resolved through the more efficient and integrated use of fossil fuels with the accompanying production of additional products. Coals, including low-grade, carbon-containing, and vegetable waste, can be recycled into combustible gases, liquid fuels, and special types of coke, or smokeless fuel briquettes. On the other hand, this requires the development of new highly efficient technologies for the preparation, recycling, and use of fuels. The article discusses theoretical and experimental studies, and also presents schemes for thermal contact fuel preparation and recycling aimed at effective integrated use of fuels in standard boilers, and boilers with a circulating fluidized bed (CFB), or in special units with waste heat boilers. In CFB boilers, heat is transferred from the circulating particles to the processed fuel by direct thermal contact. In typical boilers, fuel preparation and recycling are carried out in conveyors with a heating jacket. Recycling of coals into special types of coke is carried out in a thermal-oxidative coking unit.
Interaction of components of the mineral part of Kansko-Achinsk coals in chamber combustion technologies with regard to thermodynamic and kinetic factors
Authors: Elsukov V K
Published: April 2022

The paper considers the physical and chemical properties of ash and slag waste generated in boilers of different types. Various literature sources and the results of industrial research conducted by the author are analyzed. Factors, influencing the properties of ash and slag wastes are formulated and considered. Issues to be solved for additional use of ash from Kansko-Achinsk coals (KAC) are formulated and partially considered in terms of reducing sulphur dioxide emissions. The article shows the possibility and expediency of low-temperature flaring of KAC (at temperatures of 1450 K) and the additional use of ash in technologies of chamber combustion, as well as the necessity of taking into account the changes in the electrophysical properties of ash produced during combustion with a high fraction of SO2 binding is shown. For the sulfur dioxide (SO2) binding reaction, the kinetic and differential equations are compiled and solved. Based on the solved equations, the efficiency of ash recirculation to the upper part of the cooling chamber of the BKZ 320-140 boiler was evaluated.
Experimental study of liquid hydrocarbon combustion under conditions of steam gasification in the presence of diluent gas
Authors: Kopyev E P , Sadkin I S , Mukhina M A , Shadrin E Yu , Krasinsky D V , Shimchenko S Yu
Published: April 2022

This research is devoted to the study of the influence of diluent gas presence on liquid hydrocarbons combustion at the example of diesel fuel. Carbon dioxide was used as a diluent gas. Superheated steam was gradually replaced by carbon dioxide, which had the same temperature and delivery location, which allows performing a comparative analysis of the burner operation at different parameters of the atomizer (superheated steam, carbon dioxide, and their mixture). Temperature profiles measures along the flame symmetry axis and combustion products analysis were performed. The presence of carbon dioxide does not affect the temperature distribution at different modes. A higher diluent gas flow rate causes a slight increase in the NOx content in the flue gases.
Determination of the ignition temperature of mechanically activated carbon of various degrees of metamorphism and type of grinding
Authors: Kuznetsov A V , Pochtar A S , Vinogradov S V , Burdukov A P
Published: April 2022

The experiments carried out using two methods of TGA (thermogravimetric analysis) made it possible to determine the ignition temperatures for brown coal, hard coal and anthracite treated both with activator mills (VCM, disintegrator) and with a standard hammer mill (initial coal). Practically all the results of coal ignition obtained by different methods correlate with each other. They show a decrease in the ignition temperature of micromilled coals during mechanically activated grinding. The analysis of the results of experimental studies made it possible to calculate kinetic parameters such as the ignition index, the maximum burning rate, the burnout index, and the comprehensive index. The data obtained are new and prove the effectiveness of mechanical activation treatment of coal fuel.
Numerical study of different electron density observed in Hydrogen and Deuterium ion source plasmas
Authors: Shibata T , Kato R , Nakano H , Hayashi K , Sato J , Miyamoto K , Hoshino K , Hatayama A
Published: April 2022

Sequences of hydrogen (H) and deuterium (D) experiments have been done by NIFS research and development negative ion source (RNIS) for the deuterium NBI development. In the experiments, the co-extracted electron current with the negative ions and the electron density in the plasma generation region in the D experiment have been around three times higher than that in the H experiment. To explain the difference of the electron density in the RNIS driver region, a zero-dimensional numerical model is developed in the present study. The model only focuses on the isotope effect for vibrationally excited level of electronically grounded state molecules and its relevant cross-sections. The calculation results show that difference of the ionization channel numbers via molecular vibrationally excited states could be a reason to enhance ionization rate in D plasma.
Experiment of two-frequency heating for production of multiply charged ion at compact ECR ion source
Authors: Muramatsu Masayuki , Nomura Shinji , Harisaki Shuhei , Kato Yushi , Abe Yasushi , Watanabe Mihiro , Katagiri Ken , Kitagawa Atsushi
Published: April 2022

Several research and developments have been performed at a compact ECR ion source (Kei3) with a fixed magnetic field at HIMAC. The Kei3 is a testing machine for application of Kei series developed for high-energy carbon-ion radiotherapy. It is difficult for Kei3 to produce ions that are heavier than carbon ion because it uses the same magnetic field distribution as the Kei series. In order to improve the beam current of multiply charged ions such as neon and argon, the two-microwave-frequency heating method was tested in the Kei3. Microwaves are introduced into the plasma chamber with a WR-90 rectangular waveguide. A traveling wave tube (TWT) amplifier made by the NEC (LD79X75A1) is used as the microwave source. The frequency band is 9.75-10.25 GHz and the maximum output power is 750 W. The WR-75 waveguide is also introduced from the upper part of the upstream vacuum chamber and installed on top of the existing the WR-90 waveguide. A TWT amplifier manufactured by the Xicom (XTRD-300IJ) was used as a microwave source for the two-microwave-frequency heating. The frequency band is 10-18 GHz and the maximum output power is 300 W. A beam test with oxygen, neon, and argon was performed in order to confirm the effect of two microwave frequency heating. In this test, we focused on O6+, Ne7+, and Ar9+ ions. We measured the dependence of the XTRD-300IJ microwave frequency and the microwave power of the LD79X75A1 on a charge state distributions.
Metal evaporation study using the GANIL high temperature oven for intense metal ion beams production
Authors: Bajeat O. , Barué C. , Dubois M. , Lemagnen F. , Maunoury L. , Michel M. , Osmond B. , Royet M.
Published: April 2022

A new resistive oven dedicated to the production of metal ion beams using ECR ion sources has been developed at GANIL. It aims to produce beams such as 58Niq+, 50Tiq+, 50Vq+ or 238Uq+ with ECR4 ion source on cyclotrons injectors and with Phoenix V3 ion source on Spiral 2facility. Typical intensity about 1.2 1013 pps is requested for the Super Separator Spectrometer (S3). Evaporated atom fluxes and their angular distributions have been measured on a dedicated test bench thanks to a quartz microbalance. These investigations were carried out using three crucibles with various exit caps geometries for which the fluxes and angular distributions display distinct behaviors. Based on those results, crucible is designed to obtain a high flux of atoms overlapping the ECR plasma while minimizing the atoms losses on the ion source chamber.
Experiments to improve the performance of the GTS-LHC ECR ion source
Authors: Kövener T , Küchler D , Mahner E , Scrivens R , Baris A , Pfeiffer S , Mourier L , Vollenberg W
Published: April 2022

The GTS-LHC 14.5 GHz ECR ion source provides the ion beam, which after acceleration in the ion injector complex, is injected into the LHC, as well as being sent to fixed target experiments at CERN. Two experiments have been performed on the source. The stainless steel plasma chamber has been sputter-coated with a rather thick layer of aluminium on the surface facing the plasma; and the lead micro-oven has been modified to avoid the build-up of lead-oxide on the oven outlet. Details of the changes will be given, and results of beam measurements will be shown, with particular attention on how the stability and oven-refill schedule is impacted by these changes.
Progress on the development of key technologies for the fourth generation ECR ion source FECR
Authors: Sun L , Lu W. , Zhao H.W. , Guo J. W. , Wu W. , Wu B. M. , Ou X.J. , Mei E. M. , Zheng S.J. , Zhang X. Z. , Li L.B. , Zhu L. , Xin C. J. , Guan M.Z. , Chen Y. Q. , Wang X. D.
Published: April 2022

A 4th generation ECR (Electron Cyclotron Resonance) ion source FECR (First 4th generation ECR ion source) is under development at IMP. Aiming to be operated with the microwave power of 20 kW at 45 GHz, FECR is equipped with a fully superconducting Nb3Sn magnet and conventional parts durable for high power ECR plasma heating and optimum for intense beam production and extraction. Breakthroughs on the Nb3Sn superconducting magnet, high power density plasma chamber, high temperature oven, and so on have been successfully demonstrated recently. The prototype Nb3Sn cold mass has been successfully tested. The plasma chamber with an innovative structure of micro-channel cooling structure has been tested which enables SECRAL-II ion source operated continuously for more than 1,100 hours with ∼300 eμA Kr26+ for routine operation at the microwave power level of ∼5 kW. A high temperature inductive heating oven has also been developed and used for intense uranium beam production. This talk will present the recent progress on the development of key technologies for the 4th generation ECR ion source.
Numerical Design of RF Antennas for Ion Cyclotron Resonance Heating in ECRIS Environment
Authors: Mauro G. S. , Torrisi G. , Pidatella A. , Galatá A. , Mascali D.
Published: April 2022

In this paper we present the numerical design and simulation of RF antennas to be employed in Ion Cyclotron Resonance Heating (ICRH) systems working in ECRIS environment. A 3D full-wave numerical model, based on the coupling between COMSOL FEM solution of Maxwell equations and the MATLAB-computed non-homogeneous plasma dielectric tensor, has been employed in order to study the performances of several ICRH antennas. Results in terms of S-parameters, on-axis electric field and RF absorbed power inside the plasma chamber have been obtained and compared between the chosen antenna geometries. The presented study will permit to better understand the fundamental aspects of ion dynamics in ECRISs as well as allowing the design of a proper matching network between the RF amplifier and the antenna, necessary to cope with the plasma properties’ fast variations. Further ion kinetic simulations are ongoing.
Design and first operations of a ECR based He source at INFN-LNS
Authors: Mazzaglia M. , Amato A.S. , Battiato G. , Calabrese G. , Celona L. , Cosentino L. G. , Dantoni L. , Gammino S. , Manno G. , Marletta S. , Massara A. , Maugeri A. , Mauro G. S. , Miraglia A. , Naselli E. , Passarello S. , Pidatella A. , Piscopo M. , Russo A. D. , Seminara A. , Siliato D. , Torrisi G. , Tudisco D. , Vecchio G. , Vinciguerra S. , Mascali D. , Galatá A.
Published: April 2022

A new source for the TANDEM accelerator of LNS has been designed and installed. It is called NESTOR (Noble Elements Source for acceleraTORs) and consists of an ultra-compact ECR microwave discharge type ion source [1] operating around 6 GHz and up to 40 W of RF power, provided by a solid state power amplifier, coupled to a Li-Charge Exchange Cell (Li-CEC). It is engineered for the production of a wide range of 1+ and/or 1- ion beams from gaseous elements, in particular for noble gases. This work presents the characterization of the primary source and first operations of the whole setup on the HV platform (injector) of the Tandem. The He+ beams have been formerly characterized in terms of current, beam shape (by BaF2 beam viewers) and emittance (by the three-gradients method). Measurements have been carried out varying pressure, microwave frequency and RF power. Then, the source has been moved to the HV platform, coupled to the Li-CEC for first operations running in gas-exchange mode. Activities are ongoing to optimize beam transport towards the Tandem.
Study on influence on plasma under current-generated magnetic filter using Langmuir probe in HUST negative ion source
Authors: Yang Jinghan , Li Dong , Chen Peng , Li Zengshan , Zhang Yubo , Chen Dezhi
Published: April 2022

The current-generated magnetic filter is widely used in negative ion sources to bring down electron temperature and optimize source operation. The effect of the current-generated magnetic filter on plasma generation and transport is important. The axial distribution of cesium-free plasma parameters under different magnetic filter configurations was measured by a movable Langmuir probe at HUST negative ion source. Abnormal changes of plasma parameters are discovered at the driver exit. When the magnetic filter field penetrates into the driver, plasma density inside the driver increase, and the high-density high-temperature region of plasma expands outside of the driver. And the radiofrequency power coupling is also influenced by the magnetic filter. These experimental phenomena indicate that a new magnetic filter configuration is required to optimize source operation.
H- ion source operational performance and latest development at the Spallation Neutron Source
Authors: Han Baoxi , Stockli Martin , Welton Robert , Piller Chip , Murray Syd , Pennisi Terry , Stinson Chris , Kim Sang-Ho
Published: April 2022

The U.S. Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is the world’s most powerful accelerator-driven pulsed neutron source. An H- injector feeds the accelerator with high current (>50 mA), time structured (1ms, 60 Hz) H- beam. The injector consists of an RF-driven, Cs-enhanced H- ion source and an electrostatic low energy beam transport section. In the recent three run cycles, an H- ion source operated ∼4 months for each run with excellent availability near 99.9%. The presently ongoing run is also on track to finish another ∼4 months run with similar high availability. Lately, we have tested a solid-state RF system for the ion source to replace the existing vacuum-tube type RF amplifier for the sake of improving the ease of operation and maintenance. Progress has also been made on the continued development of an external antenna RF H- ion source with a focus on improvement to its plasma ignition scheme.
Charge Breeder at GANIL: metal charge-bred elements
Authors: Maunoury L. , Dubois M. , Damoy S. , Bajeat O. , Chauveau P. , Delahaye P. , Frigot R. , Hormigos S. , Jardin P. , Thomas J.C. , Tarvainen O.
Published: April 2022

The charge breeder of the SPIRAL1 (SP1CB) facility provided this year to physicists new Radioactive Ion Beams (RIB) for experiments and machine development, showing significantly improved performances compared to those obtained during the initial on-line commissioning of the SPIRAL 1 upgraded facility [1]. These improved performances were obtained thanks to thorough studies conducted off-line with 1+ ion beams produced by FEBIAD and ECR ion sources, successfully demonstrating the ability to couple SP1CB with them. In particular, the SP1CB established its capability to efficiently boost condensable elements such as 19Fn+, 32Sn+ and 54Fen+, in addition to more standard alkali elements. The charge breeding efficiencies have been investigated varying several parameters: buffer gas, beam transverse emittances. The ΔV curves of stable elements as well as radioactive ones were recorded for high charge states. Their trends are discussed in more detail. Finally, as molecular beams provide some advantages compared to atomic ion beams for selecting isobaric species and optimizing transport of the radioactive elements from the hot production target to the SP1CB plasma, we discuss if the charge-breeding efficiencies could also take advantage of beams in the molecular form. The performances of the 1+/N+ charge-breeding process were investigated using SF6 molecules broken into SFx
1+ ions and compared to regular F1+ and S1+ ions. This contribution will deal with these topics and latest results will be showed.
First beams from the 1+ source of the ADIGE injector for the SPES Project
Authors: Galatà A , Francescon P , Roncolato C , Bisoffi G , Ballan M , Bellan L , Bermudez J , Bortolato D , Comunian M , Conte A , Lazzari M De , Fagotti E , Gelain F , Manzolaro M , Marcato D , Martinelli V , Miglioranza M , Moisio M F , Monetti A , Munaron E , Pisent A , Rossignoli M , Roetta M , Savarese G , Scarpa D
Published: April 2022

The ADIGE (Acceleratore Di Ioni a Grande carica Esotici) injector consists of an electrostatic 1+ beam line, equipped with ion sources able to produce a wide variety of beams, coupled to a magnetic beam line, where charge multiplication is accomplished by implementing an Electron Cyclotron Resonance (ECR) based charge breeder. The injector is totally integrated in the SPES (Selective Production of Exotic Species) beam line, to allow the post-acceleration of radioactive ions and is now in an advanced phase of installation. The electrostatic 1+beam line has been put into operation and is now producing beams from alkali metals. This contribution concerns the first results of the beam commissioning of this part of the injector, with the description of the initial debug phase and the solutions adopted to ensure a reliable and continuous operation. Preliminary results of the 1+ beam line characterization will be shown, with a comparison between simulated and measured emittances.
Preliminary results of positive ion mass spectrometry based on a 2.45 GHz ECR ion source and a non-metallic gas target
Authors: Li K. , Peng S.X. , Ma T. H. , Wu W.B. , Jiang Y. X. , Cui B.J. , Zhang A. L. , Sun J. , Guo Z. Y. , Chen J. E.
Published: April 2022

Positive-ion mass spectrometry (PIMS) is a positive-to-negative ion conversion metrology that just operated on the opposite of traditional accelerator mass spectrometry (AMS) on high-precision radiocarbon dating. With a higher efficient simple structure plasma ion sources instead of AMS sputter ion sources, lower ion energy (tens keV) in place of MeV, and limited footprint facility, PIMS will be a powerful competitor to AMS in the future. To precisely measure 14C, interference of molecular isobars (such as 12CH2, 13CH) will be eliminated with higher charged ions (charge state ≥ 3; molecular cations 12CH2
2+ is metastable, can be eliminated by higher stripping pressure.), nitrogen will be eliminated inside the charge-exchange cell (CXC) through charge exchanging with target gas. To demonstrate the probability of PIMS with a 2.45 GHz ECR ion source, an experiment was launched at Peking University (PKU). A compact permanent magnet 2.45 GHz ECR ion source is designed to produce carbon ions from CO2. A CXC unit was installed after the extraction system and ethylene is chosen as charge exchange gas. Preliminary experiments prove that more than hundreds of microamp of C2+ beam can be produced with this ECR source. By injecting ethylene into CXC, several microamp C- beam was detected and the C2+ ions charge exchange efficiency to C- ions can reach close to 5%.
Electron gun producing beams with controllable current density
Authors: Pikin Alexander , Bencini Vittorio , Pahl Hannes , Wenander Fredrik
Published: April 2022

The existing Brillouin-type electron gun at the TwinEBIS test bench is, according to Herrmann theory, capable of producing an electron beam with a current density of 3850 A/cm2 in the 2 T solenoid. To control the electron beam current density and the magnetic flux inside the beam, the existing electron gun - now using purely electrostatic focusing - can be modified by permitting magnetic flux to reach the cathode. In such a configuration, the stabilizing magnetic flux inside the electron beam can be controlled by changing the current in the magnet coil surrounding the cathode. The radial oscillations of the electron beam, resulting from the increased magnetic field on the cathode, can be significantly reduced by employing a non-adiabatic magnetic field near the electron gun. This method has been recently developed and successfully used at REXEBIS at CERN. We present the computer simulations of such electro-optical system.
Analysis and Research on the Current Status of Thermal Oxidation Stability of Organic Heat Transfer Fluids
Authors: Guo Linyuan , Dai Qiang , Feng Shichun , Kong Dexin , Jin Dong
Published: April 2022

This article introduces the concept and important role of the thermal oxidation stability of the key indicators of organic heat transfer fluids, investigates the current qualified and effective organic heat transfer fluids products suitable for open and closed systems or only the proportion of closed systems, and summarizes the data of ten kinds of organic heat transfer fluids products with unqualified thermal oxidation stability were analyzed. Many enterprises still use a open system for saving one-time investment and greet convenience, strict control of the thermal oxidation stability of the organic heat transfer fluids is particularly important for the organic heat transfer fluids to be used in an open or closed system. The thermal oxidation stability of the organic heat transfer fluids has a direct and important influence on the open or closed type of the organic heat transfer fluids boiler and system, and it is directly related to the safety, environmental protection and operation of the organic heat transfer fluids boiler and system.
Optimal configuration of P2H in integrated energy system based on sequential production simulation
Authors: Han Zijiao , Ge Yanfeng , Dong Henan , Wang Liang , Li Mingzhu
Published: April 2022

In order to improve the ability of the integrated energy system to accept renewable energy, the electricity-to-hydrogen will be connected to the grid as a flexible resource. This article evaluates the value of various scenarios where electricity-to-hydrogen is used as a flexible resource. First, this paper sorts out the structure of the integrated energy system, establishes a mathematical model, and then establishes a value evaluation system for converting wind power to hydrogen to analyze the economic cost and benefit of the system. Through comparison, a brief analysis and estimation of the economics of each scene are carried out. Finally, through EnergyPLAN software for simulation, this paper takes an ecological town in Northeast China as an example, considering the typical days in winter and summer to analyze the load characteristics of the area and analyze the economic costs of each mode. The calculation example shows that a reasonable configuration of the capacity of the electricity-to-hydrogen device can achieve better economic benefits and promote the consumption of renewable energy.
Research on Electric Field Distribution and Voltage Equalization Characteristics of Tensile Insulator Strings in 750kV Substation
Authors: Zhang Xiaowen , Zhang Xu , Sun Zhiyuan , Wang Huijun
Published: April 2022

In the design process of the 750kV substation, the design of insulator strings is an important part. The design of insulator strings needs to ensure that the voltage borne by each insulator does not exceed its maximum voltage, the surface electric field strength does not exceed the discharge field strength, and the maximum economic benefits can be achieved simultaneously. In this paper, finite element calculation software is used to study the electric field distribution and voltage distribution of tensile insulator strings in 750kV substations. The relationship between the depth of the grading ring into the insulator string, the diameter of the grading ring, the diameter of the grading ring and the electric field distribution and voltage distribution of the insulator string is studied, and the recommended size of the grading ring for the 750kV insulator string is proposed to reduce the surface electric field strength of insulator strings and improve the voltage distribution of each piece of insulators. The research results have been applied to the 750kV substation designed by our institute.
Research on Weak Node Power Flow Calculation and Voltage and Reactive Power Compensation of Off Grid Microgrid
Authors: Wen Ming , li Li , Hu Hai
Published: April 2022

The voltage stability control of off grid microgrid is the key and core issue of power grid stability. Aiming at the problem of voltage stability control of off grid microgrid with unbalanced nodes, the Newton Raphson homotopy algorithm is proposed to calculate the power flow, estimate the reactive power margin of each load node, and adopt reactive power supply droop compensation control for weak nodes to improve the voltage stability level. The simulation verifies the effectiveness of this method.
Identifying Topology of Low Voltage Systems via Incorporating Measurement Correlations
Authors: Xu Jin , Zhang Wei
Published: April 2022

The management of intelligent power distribution systems is limited due to the lack of observability in low voltage (LV) systems. Ambiguous logical relations among branch units, topological unavailability of consumers increase the difficulty of topology identification (TI). To solve this problem, a three-step framework is proposed via measurement correlations. The first step applies correlations of active power features to identify the up-down and parallel, and phase connection of branch units; the second step specially calculates active power correlations between segments and non-vacant consumers, determines the phase connections, and identifies the connected lines of non-vacant consumers; the third step associates vacant consumers with non-vacant consumers by voltage profiles. Finally, robustness against errors and sample sizes is explored, and the results demonstrate that the proposed algorithm can accurately identify the LV topology based on limited samples of voltage magnitude and active power.
Preparation of Indium Tin Oxide Nanowires by Using physical-vapor-transport method
Authors: Cui Yang , Zhao Songqing , Xie Xuan , Liu Jun , Shi Hongjie
Published: April 2022

This paper presents a physical-vapor-transport method for the growth of Indium Tin Oxide (ITO) nanowires. ITO nanowires were successfully fabricated by physical vapor transport method using gold nanoparticles as catalyst prepared by two methods. The effects of holding temperature and catalyst on the growth of ITO nanowires were investigated. The experimental results show that the longer ITO nanowires can be grown by increasing the holding temperature at 850 °C, increasing the proportion of carbon powder, and using gold nanoparticles catalyst with smaller particle size. The longest ITO nanowire we fabricated is as long as 45 μm. Our experiments show that the density and diameter of ITO nanowires can be controlled by controlling the density and diameter of gold nanoparticle catalysts. The smaller the nanoparticle diameter is, the easier it is to grow long ITO nanowires.
Risk assessment of power transmission and transformation projects based on hierarchical fuzzy TOPSIS method
Authors: Lu Weiyun , Shi Songfeng , Han Dong , Ma Jian
Published: April 2022

Due to the large investment, long construction period, and extensive coverage of power grid engineering projects, it is common for project settlement and completion acceptance to lag behind. Therefore, it is of great significance to realize the reasonable control of the cost of power grid enterprises to do a good job in the transfer of power transmission and transformation projects in a timely manner and avoid the risk of transfer. Combining the current status of capital transfer in power transmission and transformation projects, and relying on the identification of key points of capital transfer in different construction stages of power transmission and transformation projects, this paper innovatively proposes a risk index system for capital transfer, and further uses the analytic hierarchy process to determine the index weights, and then uses the fuzzy TOPSIS method to construct an evaluation The model can realize the effective assessment of capital transfer risk, which can provide reference and support for improving the efficiency of capital transfer of power transmission and transformation projects in an all-round way. Finally, the operability and scientificity of the evaluation index system and evaluation method are verified by the form of an example.
The effect of lubricating oil temperature on the stability of rubbing rotor-bearing system
Authors: Huang Zhenyu
Published: April 2022

Based on the interaction between oil film force and rub impact force of fault rotor bearing system, the nonlinear dynamic equation of rotor bearing system is established to explore the influence of lubricating oil temperature on system stability. The Runge-Kutta method was used to solve the dynamic equations to analyze the steady-state characteristics of the system. The bifurcation diagrams, frequency-waterfall diagrams, time-series diagrams, axis orbit diagrams, poincare map diagrams, frequency spectra dia-grams of the system at oil temperatures of 0 ° C, 40 ° C, 80 ° C were used to reveal the nonlinear behavior of the system. The results show that the temperature mainly affects the speed and amplitude of the oil whirl. When the speed increases to oil whirl, the vibration of the system is mainly oil whirl.