Study of the fast electron behavior in electron cyclotron current driven plasma on J-TEXT

In J-TEXT tokamak,fast electron bremsstrahlung diagnostic with 9 chords equipped with multichannel analyzer enables detailed studies of the generation and transport of fast electrons.The spatial profiles and energy spectrum of the fast electrons have been measured in two ECCD cases with either on-axis or off-axis injection,and the profiles processed by Abel-inversion are consistent with the calculated power deposition locations.Moreover,it is observed that the energy of fast electrons increases rapidly after turning off the ECCD,which may be attributed to the acceleration by the recovered loop voltage at low electron density.

Suppression of runaway current by electrode biasing and limiter biasing on J-TEXT

The avoidance of runaway electrons(REs) generated during plasma disruption is of great concern for the safe operation of tokamak devices.Experimental study on the suppression of runaway current by electrode biasing(EB) and limiter biasing(LB) has been performed on the J-TEXT tokamak,which could be an alternative way to suppress the runaway current.The experimental results show that the higher the voltage value,the smaller the runaway current in both EB and LB experiments.The runaway current can be completely suppressed at an electrode biased voltage of +450 V and a limiter biased voltage of +300 V.The comparison of the energy spectra during the runaway plateau phase shows that the maximum energy max(E_(RE)) and radiation temperature T_(HXR)hard x-rays(HXRs)are significantly reduced after the application of +200 V limiter biased voltage.The electric field generated by the biased voltage may be the key factor to suppress the runaway current,and the measured radial electric field increases obviously after the voltage is applied.This may result in an increase in the loss of REs to realize the suppression of runaway current.

Investigation of electron cyclotron current drive efficiency on the J-TEXT tokamak

Electron cyclotron current drive(ECCD) efficiency research is of great importance for the neoclassical tearing mode(NTM) stabilization.Improving ECCD efficiency is beneficial for the NTM stabilization and the ECCD power threshold reduction.ECCD efficiency has been investigated on the J-TEXT tokamak.The electron cyclotron wave(ECW) power scan was performed to obtain the current drive efficiency.The current drive efficiency is derived to be approximately η_(0)=(0.06-0.16)×10^(19)A m^(-2)W^(-1)on the J-TEXT tokamak.The effect of the residual toroidal electric field has been included in the determination of the current drive efficiency,which will enhance the ECCD efficiency.At the plasma current of I_(p)=100 kA and electron density of n_(e)=1.5×10^(19)m^(-3),the ratio of Spitzer conductivity between omhic(OH)and ECCD phases is considered and the experimental data have been corrected.The correction results show that the current drive efficiency η_(1)caused by the fast electron hot conductivity decreases by approximately 79%.It can be estimated that the driven current is approximately 24 kA at 300 kW ECW power.

微米阵列结构聚合物薄膜的制备及其对细胞三维培养的影响

二维(Two-dimensional,2D)细胞实验模型是目前研究人类疾病的细胞过程和药物筛选的主流方法。然而,生物细胞的生长受到众多因素的影响,传统的2D细胞培养在精确再现三维组织内细胞的功能方面存在一些障碍。与2D细胞培养相比,三维(Three-dimensional,3D)细胞培养体系注重细胞间的接触及细胞-基质间的接触,更接近于生物体的生长环境,更适合于药物筛选、细胞培植等研究。文中通过纳米压印技术制备了不同结构微米阵列聚合物薄膜,并将其应用于293T细胞的培养,通过调节薄膜表面结构、表面接触角成功实现了对生物细胞生长形貌的调控。利用扫描电镜等方法,对比了聚合物薄膜不同微结构、不同表面润湿性对细胞生长形貌的影响,重点关注细胞团的形态变化。结果表明,细胞在亲水性10μm柱形阵列薄膜上呈现三维生长状态,这种薄膜可能更适用于制备生物细胞3D培养基;疏水性3μm柱形阵列薄膜适用于体积小、表皮硬的组织细胞的3D培养,对于体积较大的细胞效果差。另外,对于疏水性较强的薄膜,细胞倾向于球状生长,而亲水性较强的薄膜则易贴壁生长。研究结果为微结构薄膜在生物细胞3D培养方面的应用作了初步探索。

Fabrication of low-resistance LaNi_xO_(3+δ) thin films for ferroelectric device electrodes

LaNiO3 thin films with different La/Ni ratios were deposited on Si substrates by sol-gel process. The electrical resistivities of LaNixO3＋δfilms with different La/Ni ratios were measured by four-probe method.LaNi（0.95）O3＋δthin film has the lowest resistivity. First-principle calculations show that LaNi（0.95）O3＋δhas the largest Ni-O-Ni bond angle and the shortest Ni-O bond length, which means LaNi（0.95）O3＋δhas the strongest metallic property, hence, the electrical resistivity is the lowest. Au/PZT（PbZr（0.52）Ti（0.48）O3）/LaNixO3＋δand Au/PZT/Pt ferroelectric capacitors were fabricated to evaluate LaNixO3＋δas a bottom electrode. It is shown that fatigue properties of PZT films can be significantly improved by using LaNixO3＋δinstead of Pt as the bottom electrode. The Ⅰ-Ⅴ test results of PZT films show that LaNi（0.95）O3＋δas bottom electrode can reduce the threshold voltages of PZT films, suggesting that La/Ni ratio in LaNixO3＋δas a large influence on the film properties.

First mapping of China surface movement using supercomputing interferometric SAR technique

The Earth surface is constantly moving and changing under the influence of internal and external dynamic geological processes and human activities.On a time scale,such changes may occur within a few seconds,such as earthquakes and landslides,or last for several years or even longer,such as fault creep and frozen soil degradation.On a spatial scale,such changes may manifest as local surface collapses or regional surface subsidence.

Enhanced performance triboelectric nanogenerator based on porous structure C/MnO_(2)nanocomposite for energy harvesting

Triboelectric nanogenerator(TENG)can realize a variety of mechanical energy collections in the environment,which has great potential in the field of wearable energy.However,many TENGs could rarely be satisfactory to wearable electronics promotion because of their expensive raw materials and complex manufacturing processes.In this study,a type of porous structure carbon powder/manganese dioxide(C/MnO_(2))nanocomposite is introduced.The material adopts low-cost,high-yield carbon powder,can be prepared in one step through a simple,economical,and environmentally friendly hydrothermal preparation process,and has high economic practicality.Superior power generation performance was obtained by modulating the charge trapping ability and storage capacity of polydimethylsiloxane@C/MnO_(2)(PDMS@C/MnO_(2))film based on variations in the weight-loading of C/MnO_(2).The maximum output voltage of carbon powder/manganese dioxide TENG(CM-TENG)is 63 V,which is 2.1 times that of PDMS-TENG and 1.86 times that of carbon powder TENG(C-TENG)and can easily light up 53 LEDs.Furthermore,CM-TENG can convert biological motion energy into electrical signals to detect human hand movements.The CM-TENG self-powered system can successfully drive various microelectronic devices,such as electronic watches,liquid crystal displays(LCDs),and calculators.This study provides a reliable,low-cost,high-performance,and widely applicable electronic system that shows great potential in future fields such as wearable devices and micro-sensing systems.