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

Lactobacillus plantarum ZLP001: In vitro Assessment of Antioxidant Capacity and Effect on Growth Performance and Antioxidant Status in Weaning Piglets

Wang, J.,Ji, H.F.,Wang, S.X.,Zhang, D.Y.,Liu, H.,Shan, D.C.,Wang, Y.M. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.8

The objective of this study was to evaluate the antioxidant capacity of Lactobacillus plantarum ZLP001 and its effects on growth performance and antioxidant status in weaning piglets. The survival in hydrogen peroxide and free radical-scavenging activity of Lactobacillus plantarum ZLP001 were analysed in vitro. The Lactobacillus plantarum ZLP001 showed high viability in 1.0 mmol/L hydrogen peroxide and high scavenging ability against hydroxyl, superoxide anion, and DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals which was dose dependent. Ninety-six weaning piglets were selected ($7.45{\pm}0.79kg$) and divided into three groups comprising of negative control without any supplementation, treatment group with supplemented $6.8{\times}10^7$ Lactobacillus plantarum ZLP001 CFU/g of diet, and positive control with antibiotic treatment (chlorotetracycline, 80 mg/kg diet). The results showed that Lactobacillus plantarum ZLP001 supplementation enhanced feed conversion rates in piglets compared with control (p<0.05). Supplementation of Lactobacillus plantarum ZLP001 increased the concentration of superoxide dismutase (p<0.05), glutathione peroxidase (p<0.01) and catalase in serum (p<0.10), while decreased the concentration of malondialdehyde (p<0.05). The present study implies that the strain Lactobacillus plantarum ZLP001 had high antioxidant ability and its supplementation improved the growth performance and antioxidant status of weaning piglets, so it can be considered useful to alleviate oxidative stress and increase productive performance of pigs.

Experimental investigation on effect of ion cyclotron resonance heating on density fluctuation in SOL at EAST

Y.C. Li,M.H. Li,M. Wang,L. Liu,X.J. Zhang,C.M. Qin,Y.F. Wang,C.B. Wu,L.N. Liu,J.C. Xu,B. J. Ding,X. D. Lin,B. J. Ding,X. D. Lin,J. F. Shan,F. K. Liu,Y. P. Zhao,T. Zhang,X. Gao 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

The suppression of high-intensity blob structures in the scrape-off layer (SOL) by ion-cyclotron range offrequencies (ICRF) power, leading to a decrease in the turbulent fluctuation level, is observed first in theExperimental Advanced Superconducting Tokamak (EAST) experiment. This suppression effect from ICRFpower injection is global in the whole SOL at EAST, i.e. blob structures both in the regions that aremagnetically connected to the active ICRF launcher and in the regions that are not connected to theactive ICRF launcher could be suppressed by ICRF power. However, more ICRF power is required to reachthe full blob structure suppression effect in the regions that are magnetically unconnected to the activelauncher than in the regions that are magnetically connected to the active launcher. Studies show that apossible reason for the blob suppression could be the enhanced Er B shear flow in the SOL, which issupported by the shaper radial gradient in the floating potential profiles sensed by the divertor probearrays with increasing ICRF power. The local RF wave power unabsorbed by the core plasma isresponsible for the modification of potential profiles in the SOL regions.

Structural, electrical, and optical properties of Na-doped ZnO thin films deposited by pulsed laser deposition.

Shan, F K,Liu, G X,Lee, W J,Bae, K R,Shin, B C,Kim, H S American Scientific Publishers 2008 Journal of Nanoscience and Nanotechnology Vol.8 No.10

<P>Na-doped ZnO thin films were deposited on quartz substrates at various temperatures by using pulsed laser deposition technique. An X-ray diffractometer and an atomic force microscope were used to investigate the structural and morphological properties of the thin films. A Hall effect measurement system was used to investigate the electrical properties of the thin films. A spectrophotometer was used to measure the transmittances of the thin films. The band gap energies of the thin films were calculated by linear fitting the sharp absorption edge for high-quality thin film. The band gap energies of the Na-doped ZnO thin films are nearly the same as the pure ZnO. A spectrometer was used to investigate the luminescent properties of the thin films. The thin film deposited at 200 degrees C had no near band edge emission and no deep-level emission. The NBE emission appeared and increased with increasing the growth temperature.</P>

Annealing Dependence of Solution-Processed Ultra-Thin ZrOx Films for Gate Dielectric Applications.

Liu, G X,Liu, A,Meng, Y,Shan, F K,Shin, B C,Lee, W J,Cho, C R American Scientific Publishers 2015 Journal of Nanoscience and Nanotechnology Vol.15 No.3

<P>Ultra-thin ZrOx thin films on Si substrates were prepared by sol-gel technique and processed with different methods (baked on hot plate at 150 °C, annealed at 500 °C in furnace, and photo-annealed under UV light). The decomposition of the organic groups and the formation of Zr-O bonding in the ZrOx thin films were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It is found that the ZrOx thin film annealed under UV light shows decent characteristics, including an ultra-small surface roughness, a low leakage current density of 10(-9) A/cm2 at 1 MV/cm, a large breakdown electric field of 9.5 MV/cm, and a large areal capacitance of 775 nF/cm2.</P>

PLD를 이용한 Antimony가 도핑된 p 형 ZnO 박막의 구현

배기열,이동욱,이원재,배윤미,신병철,김일수,Bae, Ki-Ryeol,Lee, Dong-Wook,Elanchezhiyan, J.,Lee, Won-Jae,Bae, Yun-Mi,Shin, Byoung-Chul,Kim, Il-Soo,Shan, F.K. 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.10

Antimony (Sb) doped ZnO thin films (0.1 at.%) were deposited on sapphire (0001) substrates at various temperatures (200 - 600$^{\circ}C$) by using pulsed laser deposition technique. All the thin films have been characterized by X-ray diffractometer, atomic force microscopy and spectrophotometer to investigate their structural, morphological and optical properties, respectively. Hall measurements were also carried out to identify the electrical properties of the thin films. These thin films were constituted in wurtzite structure with the preferential orientation of (002) diffraction plane and had as high as 80% optical transmission in the visible range. The bandgap energy also was determined by spectrophotometer which was around 3.28 eV. Hall measurements results revealed that the Sb dope ZnO thin film (0.1 at.%) grown at $500^{\circ}C$ exhibited p-type conduction with a carrier concentration of $8.633\times10^{16}\;cm^{-3}$, a mobility of $1.41\;cm^2/V{\cdot}s$ and a resistivity of $51.8\;\Omega{\cdot}cm$. We have successfully achieved p-type conduction in antimony doped ZnO thin films with low doping level even though the electrical properties are not favorable. This paper suggests the feasibility of p-type doping with large-size-mismatched dopant by using pulsed laser deposition.

Low operating voltage InGaZnO thin-film transistors based on Al2O3 high-k dielectrics fabricated using pulsed laser deposition

Geng, G. Z.,Liu, G. X.,Zhang, Q.,Shan, F. K.,Lee, W. J.,Shin, B. C.,Cho, C. R. Korean Physical Society 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.10

Low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with an Al2O3 dielectric were fabricated on a Si substrate by using pulsed laser deposition. Both Al2O3 and IGZO thin films are amorphous, and the thin films have very smooth surfaces. The Al2O3 gate dielectric exhibits a very low leakage current density of 1.3 x 10(-8) A/cm(2) at 5 V and a high capacitance density of 60.9 nF/cm(2). The IGZO TFT with a structure of Ni/IGZO/Al2O3/Si exhibits high performance with a low threshold voltage of 1.18 V, a high field effect mobility of 20.25 cm(2)V(-1)s(-1), an ultra small subthreshold swing of 87 mV/decade, and a high on/off current ratio of 3 x 10(7).

Optical Characterizations of ZnO Thin Films on Si (100) Substrates Deposited by Pulsed Laser Deposition

F. K. Shan,B. C. Shin,G. H. Lee,G. X. Liu,I. S. Kim,W. J. Lee,Y. S. Yu,Z. F. Liu 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

ZnO thin films were deposited on Si (100) substrates at different temperatures (100600 ℃) in the pulsed laser deposition (PLD) system. Micro-Raman, spectroscopic ellipsometry (SE), and spectrometry techniques were used to characterize the thin films. Raman spectra of the thin films revealed the E2 modes at around 99 and 436 cmက1, which indicates that the wurtzite structure is easily formed in the thin films. As a function of growth temperature, greater tensile stress is induced at lower growth temperature. The Sellmeier relation was used to simulate SE data ( and ). The refractive indices and thicknesses of the thin films were extracted by the simulation. The refractive indices of the thin films deposited at temperatures higher than 300 ℃ show normal dispersion behavior in the wavelength range concerned. However, the refractive indices of the thin films deposited at 200 ℃ deviate from the normal values. ZnO thin films deposited at room temperature were annealed in a PLD chamber and a rapid thermal annealing system, respectively. The annealing effects on the luminescent properties were observed. It was found that the optical properties of ZnO thin films deposited at room temperature could be greatly improved by a post-annealing process.

Annealing Effects of ZnO Thin Films Deposited on Si (100) by Using Pulsed Laser Deposition

F. K. Shan,G. X. Liu,B. C. Shin,W. J. Lee 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

ZnO thin films were deposited on Si (100) substrates at different temperatures by using pulsed laser deposition technique. An X-ray diffractometer (XRD), a scanning probe microscope and a spectrometer were used to investigate the structural, morphological and luminescent properties of the thin films. We found that the thin films had a preferred (002) orientation and that the peak intensity of the (002) orientation increased with increasing growth temperature up to 400℃. However, the peak intensity decreased when the growth temperature was over 500℃. The grain size and the roughness of the thin films depended on the growth temperature. The higher the growth temperature, the rougher the surface and the bigger the grain size. The photoluminescence (PL) of the thin films deposited at temperatures lower than 500℃ showed near-band-edge (NBE) and deep-level (DL) emissions. The peak intensity of the NBE emission increased with increasing growth temperature. The annealing effects of the thin films grown at room temperature were observed and characterized. We observed that the XRD patterns and the surface morphologies of the as-deposited thin film and the post-annealed films were little different. However, the PL spectra of the thin films annealed at different temperatures were quite different. In order to find the origin of DL emission of the as-deposited thin film, we annealed the thin films in a N2 ambient. We conclude that the DL emissions of the as-deposited ZnO thin film originated from oxygen vacancies instead of zinc interstitials. ZnO thin films were deposited on Si (100) substrates at different temperatures by using pulsed laser deposition technique. An X-ray diffractometer (XRD), a scanning probe microscope and a spectrometer were used to investigate the structural, morphological and luminescent properties of the thin films. We found that the thin films had a preferred (002) orientation and that the peak intensity of the (002) orientation increased with increasing growth temperature up to 400℃. However, the peak intensity decreased when the growth temperature was over 500℃. The grain size and the roughness of the thin films depended on the growth temperature. The higher the growth temperature, the rougher the surface and the bigger the grain size. The photoluminescence (PL) of the thin films deposited at temperatures lower than 500℃ showed near-band-edge (NBE) and deep-level (DL) emissions. The peak intensity of the NBE emission increased with increasing growth temperature. The annealing effects of the thin films grown at room temperature were observed and characterized. We observed that the XRD patterns and the surface morphologies of the as-deposited thin film and the post-annealed films were little different. However, the PL spectra of the thin films annealed at different temperatures were quite different. In order to find the origin of DL emission of the as-deposited thin film, we annealed the thin films in a N2 ambient. We conclude that the DL emissions of the as-deposited ZnO thin film originated from oxygen vacancies instead of zinc interstitials.

Channel Layer Thickness Dependence of In-Ti-Zn-O Thin-film Transistors Fabricated Using Pulsed Laser Deposition

Q. Zhang,F. K. Shan,G. X. Liu,A. Liu,W. J. Lee,B. C. Shin 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.10

Amorphous indium-titanium-zinc-oxide (ITZO) thin-film transistors (TFTs) with various channelthicknesses were fabricated at room temperature by using pulsed laser deposition. The channellayer thickness (CLT) dependence of the TFTs was investigated. All the ITZO thin films wereamorphous, and the surface roughnesses decreased slightly first and then increased with increasingCLT. With increasing CLT from 35 to 140 nm, the on/off current ratio and the field-effect mobilityincreased, and the subthreshold swing decreased. The TFT with a CLT of 210 nm exhibited theworst performance, while the ITZO TFT with a CLT of 140 nm exhibited the best performancewith a subthreshold voltage of 2.86 V, a mobility of 53.9 cm2V−1s−1, a subthreshold swing of 0.29V/decade and an on/off current ratio of 109.