R&D Status of High-current Accelerators at IFP

J. J. Deng,J. S. Shi,W. P. Xie,L. W. Zhang,K. Z. Zhang,S. P. Feng,J. Li,M. Wang,Y. He,L. S. Xia,Z. Y. Dai,H. T. Li,L. Wen,S. F. Chen,X. Li,Q. G. Lai,M. H. Xia,Y. C. Guan,S. Y. Song,L. Chen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61

High-current accelerators have many important applications in Z-pinches, high-power microwaves, and free electron lasers, imploding liners and radiography and so on. Research activities on Zpinches, imploding liners, radiography at the Institute of Fluid Physics (IFP) are introduced. Several main high-current accelerators developed and being developed at IFP are described, such as the Linear Induction Accelerator X-Ray Facility Upgrade (LIAXFU, 12 MeV, 2.5 kA, 90 ns), the Dragon-I linear induction accelerator (20 MeV, 2.5 kA, 60 ns), and the Primary Test Stand for Z-pinch (PTS, 10 MA, 120 ns). The design of Dragon-II linear induction accelerator (20 MeV, 2.5 kA, 3 × 60 ns) to be built will be presented briefly.

Effects of Immune Stress on Performance Parameters, Intestinal Enzyme Activity and mRNA Expression of Intestinal Transporters in Broiler Chickens

Feng, Y.,Yang, X.J.,Wang, Y.B.,Li, W.L.,Liu, Y.,Yin, R.Q.,Yao, J.H. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.5

Immune stress is the loss of immune homeostasis caused by external forces. The purpose of this experiment was to investigate the effects of immune stress on the growth performance, small intestinal enzymes and peristalsis rate, and mRNA expression of nutrient transporters in broiler chickens. Four hundred and thirty-two 1-d-old broilers (Cobb500) were randomly assigned to four groups for treatment; each group included nine cages with 12 birds per cage. Group 1 = no vaccine (NV); Group 2 = conventional vaccine (CV); group 3 = lipopolysaccharide (LPS)+conventional vaccine (LPS); group 4 = cyclophosphamide (CYP)+conventional vaccine (CYP). The results demonstrated that immune stress by LPS and CYP reduced body weight gain (BWG), feed intake (FI), small intestine peristalsis rate and sIgA content in small intestinal digesta (p<0.05). However, the feed conversion ratio (FCR) remained unchanged during the feeding period. LPS and CYP increased intestinal enzyme activity, relative expression of SGLT-1, CaBP-D28k and L-FABP mRNAs (p<0.05). LPS and CYP injection had a negative effect on the growth performance of healthy broiler chickens. The present study demonstrated that NV and CV could improve growth performance while enzyme activity in small intestine and relative expression of nutrient transporter mRNA of NV and CV were decreased in the conditions of a controlled rational feeding environment. It is generally recommended that broilers only need to be vaccinated for the diseases to which they might be exposed.

Neutron diffraction measurements of residual stresses in friction stir welding: a review

Woo, W,Feng, Z,Wang, X&#x2010,l,David, S A Informa UK (Taylor Francis) 2011 Science and technology of welding and joining Vol.16 No.1

Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides

Bahramy, M. ,S.,Clark, O. ,J.,Yang, B.-J.,Feng, J.,Bawden, L.,Riley, J. ,M.,Markovi&#x107,, I.,Mazzola, F.,Sunko, V.,Biswas, D.,Cooil, S. ,P.,Jorge, M.,Wells, J. ,W.,Leandersson, M Nature Publishing Group, a division of Macmillan P 2018 NATURE MATERIALS Vol.17 No.1

Transition-metal dichalcogenides (TMDs) are renowned for their rich and varied bulk properties, while their single-layer variants have become one of the most prominent examples of two-dimensional materials beyond graphene. Their disparate ground states largely depend on transition metal d-electron-derived electronic states, on which the vast majority of attention has been concentrated to date. Here, we focus on the chalcogen-derived states. From density-functional theory calculations together with spin- and angle-resolved photoemission, we find that these generically host a co-existence of type-I and type-II three-dimensional bulk Dirac fermions as well as ladders of topological surface states and surface resonances. We demonstrate how these naturally arise within a single p-orbital manifold as a general consequence of a trigonal crystal field, and as such can be expected across a large number of compounds. Already, we demonstrate their existence in six separate TMDs, opening routes to tune, and ultimately exploit, their topological physics.

Fabrications and dielectric performances of novel composites: Calcium copper titanate / Polyvinylidene fluoride

Wang J.J.,Deng Q.J.,He Y.Y.,Feng Y.N.,Kang M.P.,Duan X.L.,Yang Y.L. 한국물리학회 2022 Current Applied Physics Vol.39 No.-

CCTO (Calcium copper titanate) powder as inorganic filler was synthesized by the Sol-gel method firstly. CCTO/ PVDF (Polyvinylidene fluoride) composite was fabricated by solution mixing based on high temperature resistance of PVDF and insulated property of CCTO. The composite of CCTO/PVDF were characterized by X-ray diffraction, Fourier Transform infrared spectroscopy, Scanning Electron Microscope and impedance analysis. The results showed that the addition of CCTO and increasing in its content did not affect the phase- and microstructure of the composites,but the increase of CCTO content can induce the generation of C–F new bonds. PVDF/CCTO composites were enhanced in performance of thermal and frequency-depended stability with increasing in the fraction of CCTO. The dielectric constant of CCTO/PVDF composite materials with 50% CCTO achieved to a maximum value of 50 almost, which is 5 times higher the pure PVDF. The conductivity felled into 10-8 to 10-1 S m-1 during the frequency of 102–108 Hz. The composite material would be expected to be applied in the field of integrated circuit.

Spectroscopic Ellipsometric Study of Size-Controlled Silicon Nano-Crystals in SiO2 Composite Thin Film

S.-Z. Feng,L.-Y. Chen,J. Li,P.-H. Mao,R.-J. Zhang,X.-F. Li,Y.-X. Zheng 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II

In this work, a series of SiO$_x$/SiO$_2$ superlattices were prepared, by using reactive evaporation, with different thicknesses of the SiO$_x$ layers. After being annealed at 1100 $^\circ$C, composite thin films with the nano-crystals of silicon (nc-Si) embedded in the SiO$_2$ layers were formed. The optical properties of the films were measured by using the spectroscopic ellipsometric (SE) method in the photon energy range from 1.5 to 4.5 eV at three different incidence angles of 65$^\circ$, 70$^\circ$ and 75$^\circ$. In terms of the ellipsometric data, the effective medium approximation (EMA) with the four-parameter Lorentz oscillator model was used to fit the spectra and to extract the optical dispersion of the nc-Si particles. We found that the dielectric functions of the composite films strongly depended on the volume fraction of nc-Si and the constant of the SiO$_2$ layers, which changed with the composition in the investigated spectrum range

Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST

Wang M.,Liu L.,Zhao L.M.,Li M.H.,Ma W.D.,Hu H.C.,Wu Z.G.,Feng J.Q.,Yang Y.,Zhu L.,Chen M.,Zhou T.A.,Jia H.,Zhang J.,Cao L.,Zhang L.,Liang R.R.,Ding B.J.,Zhang X.J.,Shan J.F.,Liu F.K.,Ekedahl A.,Gonich 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2 . Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 C, much below the permissible value of tungsten material (~1200 C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-activemultijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5 toroidally from the 4.6 GHz LH system and is not magnetically connected

NOVEL STABILITY CONTROL STRATEGY FOR DISTRIBUTED DRIVE ELECTRIC VEHICLE BASED ON DRIVER OPERATION INTENTION

L. XIONG,G. W. TENG,Z.-P. YU,W. X. ZHANG,Y. FENG 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.4

In this paper, a novel direct yaw control method based on driver operation intention for stability control of a distributed drive electric vehicle is proposed. It was discovered that the vehicle loses its stability easily under an emergency steering alignment (EA) problem. An emergent control algorithm is proposed to improve vehicle stability under such a condition. A driver operation intention recognition module is developed to identify the driving conditions. When the vehicle enters into an EA condition, the module can quickly identify it and transfer the control method from normal direct yaw control to emergency control. Two control algorithms are designed. The emergency control algorithm is applied to an EA condition while the adaptive control algorithm is applied to other conditions except the EA condition. Both simulation results and real vehicle results show that: The driver module can accurately identify driving conditions based on driver operation intention. When the vehicle enters into EA condition, the emergent control algorithm can intervene quickly, and it has proven to outperform normal direct yaw control for better stabilization of vehicles.

Effects of Fabric Surface Energy on Human Thermophysiological Responses during Exercise and Recovery

Zhou, L.Y.,Li, Y.,Chung, J.,Tokura, H.,Gohel, M.D.I.,Kwok, Y.L.,Feng, X.W. The Korean Fiber Society 2007 Fibers and polymers Vol.8 No.3

The present paper reports a study on influences of fabric surface energy of cotton and polyester garments on clothing microclimates and human thermophysiological responses during intermittent exercise and recovery. Eight healthy males wearing the garments prepared performed exercises and rest according to the following protocol: rest for 30 min, run on treadmill for total 60 min of three sessions with different intensity and duration, and then sit quietly for 30 min for recovery, all at $30^{\circ}C$ and relative humidity of 30 %, while the microclimate humidity ($H_{mc}$) and temperature ($T_{mc}$), the clothing outside surface humidity ($H_{co}$) and temperature ($T_{co}$), the skin temperatures and ear canal temperature ($T_{ear_canal})$ were measured. The garments are made of: (a) hydrophilic and hydrophobic cotton knitted fabrics, and (b) hydrophilic and hydrophobic polyester knitted fabrics. During and after exercise, for cotton, hydrophilic garment resulted in significant lower ${\Delta}H_{mc}$, ${\Delta}H_{co}$, ${\Delta}T_{mc}$, during recovery, higher ${\Delta}{\bar{T}}_{sk}$, lower ${\Delta}T_{ear_canal}$ and ${\Delta}T_{forehead}$. For polyester, hydrophilic garment resulted in significantly lower ${\Delta}H_{co}$, ${\Delta}T_{co}$, higher ${\Delta}T_{forehead}$, during E1, E2 and recovery session but lower during E3. In summary, surface energy of cotton garments had significant influences on human thermophysiological responses during exercise and recovery, and hydrophilic cotton garment was better than hydrophobic one to reduce heat stress. Surface energy of polyester garments had influences of lower significance, and hydrophilic garment appeared better than hydrophobic garment.

A First-Principles Study of the Thermodynamic Properties of GaAs under Intense Electronic Excitation

S. Q. Feng,H. N. Li,B. M. Li,X. L. Cheng 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.11

In this paper, we present the phonon dispersion curves of Gallium arsenide (GaAs) at different electronic temperatures. Based on the phonon spectra, we further investigated the thermodynamic properties of GaAs under intense electronic excitation. The phonon entropy, phonon heat capacity and phonon contribution to the Helmholtz free energy and the internal energy as functions of temperature at different electronic temperatures are calculated. A sudden change in the phonon entropy-temperature curve from T e = 1.25 to 1.5 eV provides an indication of GaAs undergoing a phase transition from a solid to a liquid. This can be considered as collateral evidence for the non-thermal melting of GaAs under electronic excitation.