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1.
LI Xiongwei 《等离子体科学和技术》2015,17(11):928-932
The carbon content of bituminous coal samples was analyzed by laser-induced break?down spectroscopy. The 266 nm laser radiation was utilized for laser ablation and plasma gener?ation in air. The partial least square method and the dominant factor based PLS method were used to improve the measurement accuracy of the carbon content of coal. The results showed that the PLS model could achieve good measurement accuracy, and the dominant factor based PLS model could further improve the measurement accuracy. The coefficient of determination and the root-mean-square error of prediction of the PLS model were 0.97 and 2.19%, respectively; and those values for the dominant factor based PLS model were 0.99 and 1.51%, respectively. The results demonstrated that the 266 nm wavelength could accurately measure the carbon content of bituminous coal. 相似文献
2.
Mingjing ZHAO 《等离子体科学和技术》2020,22(7):74003-074003
pH is one of the significant properties of soil,and is closely related to the decomposition of soil organic matter,anion-cation balance,growth of plants and many other soil processes.In the present work,laser-induced breakdown spectroscopy(LIBS) technique coupled with random forest(RF) was proposed to quantify the pH of soil.First,LIBS spectra of soil was collected,and some common elements in soil were identified based on the National Institute of Science and Technology database.Then,in order to obtain a better predictive result,the influence of different input variables(full spectrum,different spectral ranges,the intensity of characteristic bands and characteristic lines) on the predictive performance of RF calibration model was explored with the evaluation indicators of root mean square error(RMSE) and coefficient of determination(R2),the characteristic bands of four elements(AI,Ca,Mg and Si) were determined as the optimal input variables.Finally,the predictive performance of RF calibration model was compared with partial least squares calibration model with the optimal input variables and model parameters,and RF calibration model showed a better predictive performance,and the four evaluation indicators of R_p~2,RMSEP,mean absolute error and mean relative error were 0.9687,0.1285,0.1114 and 0.0136,respectively.It indicates that LIBS technique coupled with RF algorithm is an effective method for pH determination of soil. 相似文献
3.
为研究核电厂H3BO3-NaOH-H2O溶液结晶机理,选择钠硼比(K)、pH值、硼浓度以及晃动和杂质作为影响因素,通过实验研究各影响因素对溶液结晶的影响和不同K值范围内溶液的主要成分。结果显示：K<0.2(pH<7.5)时,溶液的主要成分是硼酸,溶液结晶温度随K值或pH值的增大显著下降;0.2＜K＜0.4(7.0＜pH＜8.5)时,溶液的主要成分是五硼酸盐,硼浓度低于25 000 ppm的溶液在5 ℃均不结晶;0.40.8时,溶液的主要成分是偏硼酸钠。另外,晃动和杂质均加速溶液结晶。综合考虑各因素对溶液体系结晶的影响,在核电厂浓缩液硼浓度目标控制值为15 000 ppm、厂房最低环境温度5 ℃下,溶液不结晶的推荐K值控制范围为0.20～0.25,最佳K值为0.23。 相似文献
4.
Fan DENG 《等离子体科学和技术》2020,22(7):74005-074005
Coal is a crucial fossil energy in today's society,and the detection of sulfir(S) and nitrogen(N)in coal is essential for the evaluation of coal quality.Therefore,an efficient method is needed to quantitatively analyze N and S content in coal,to achieve the purpose of clean utilization of coal.This study applied laser-induced breakdown spectroscopy(LIBS) to test coal quality,and combined two variable selection algorithms,competitive adaptive reweighted sampling(CARS) and the successive projections algorithm(SPA),to establish the corresponding partial least square(PLS) model.The results of the experiment were as follows.The PLS modeled with the full spectrum of 27,620 variables has poor accuracy,the coefficient of determination of the test set(R~2 P) and root mean square error of the test set(RMSEP) of nitrogen were 0.5172 and 0.2263,respectively,and those of sulfur were0.5784 and 0.5811,respectively.The CARS-PLS screened 37 and 25 variables respectively in the detection of N and S elements,but the prediction ability of the model did not improve significantly.SPA-PLS finally screened 14 and 11 variables respectively through successive projections,and obtained the best prediction effect among the three methods.The R~2 P and RMSEP of nitrogen were0.9873 and 0.0208,respectively,and those of sulfur were 0.9451 and 0.2082,respectively.In general,the predictive results of the two elements increased by about 90% for RMSEP and 60% for R2 P compared with PLS.The results show that LIBS combined with SPA-PLS has good potential for detecting N and S content in coal,and is a very promising technology for industrial application. 相似文献
5.
LI Xiongwei 《等离子体科学和技术》2015,17(8):621-624
The wavelength dependence of laser induced breakdown spectroscopy(LIBS) in the analysis of the carbon contents of coal was studied using 266 nm and 1064 nm laser radiations.Compared with the 1064 nm wavelength laser ablation,the 266 nm wavelength laser ablation has less thermal effects,resulting in a better crater morphology on the coal pellets.Besides,the 266 nm wavelength laser ablation also provides better laser-sample coupling and less plasma shielding,resulting in a higher carbon line intensity and better signal reproducibility.The carbon contents in the bituminous coal samples have better linearity with the line intensities of atomic carbon measured by the 266 nm wavelength than those measured by the 1064 nm wavelength.The partial least square(PLS) model was established for the quantitative analysis of the carbon content in coal samples by LIBS.The results show that both of the 266 nm and 1064 nm wavelengths are capable of achieving good performance for the quantitative analysis of carbon content in coal using the PLS method. 相似文献
6.
《等离子体科学和技术》2024,26(2)
Rapid online analysis of liquid slag is essential for optimizing the quality and energy efficiency of steel production.To investigate the key factors that affect the online measurement of refined slag using laser-induced breakdown spectroscopy(LIBS),this study examined the effects of slag composition and temperature on the intensity and stability of the LIBS spectra.The experimental temperature was controlled at three levels:1350 ℃,1400 ℃,and 1450 ℃.The results showed that slag composition and temperature significantly affected the intensity and stability of the LIBS spectra.Increasing the Fe content and temperature in the slag reduces its viscosity,resulting in an enhanced intensity and stability of the LIBS spectra.Additionally,42 refined slag samples were quantitatively analyzed for Fe,Si,Ca,Mg,Al,and Mn at 1350 ℃,1400 ℃,and 1450 ℃.The normalized full spectrum combined with partial least squares(PLS)quantification modeling was used,using the Ca Ⅱ 317.91 nm spectral line as an internal standard.The results show that using the internal standard normalization method can significantly reduce the influence of spectral fluctuations.Meanwhile,a temperature of 1450 ℃ has been found to yield superior results compared to both 1350 ℃ and 1400 ℃,and it is advantageous to conduct a quantitative analysis of the slag when it is in a\"water-like\"state with low viscosity. 相似文献
7.
In this paper, a low-pressure capacitively coupled plasma discharge sustained in an argonoxygenmixture was studied in order to evaluate its properties in terms of inactivation ofStaphylococcus aureus. The plasma parameters as electron temperature and plasma density weremeasured by the Langmuir probe (Ne ≈ 1015 m−3, Te ≈ 1.5 eV), while the neutral atom densitywas in the range of 1021 m−3. In the plasma phase, oxygen radicals were taken as reference of thereactive species with antimicrobial activity, and oxygen spectral lines, over a range of plasmaprocess parameters, were investigated by the optical emission spectroscopy. Optimal plasmaconditions were found, and a count reduction of 4 log in a few minutes of the bacterium provesthe potentiality of an industrial grade plasma reactor as a sterilization agent. 相似文献
8.
LIU Yong 《等离子体科学和技术》2011,13(3):352-356
Present status of the diagnostics for electron cyclotron emission measurements on both HT-7 and EAST is reported. A 16-channel heterodyne radiometer system and a 20-channel grating polychromator, have been installed on HT-7 and EAST. A 32-channel heterodyne ra- diometer system, with a wider frequency coverage and better spatial resolution, is being built. In order to provide a reliable electron temperature profi, an in-situ absolute calibration system is currently being built. With the ECE measurements, study on the electron heat transport and the anomalous Doppler resonance is conducted. 相似文献
9.
PUREX流程中,萃取剂和稀释剂在强辐照场下会发生辐解,部分辐解产物使Pu（Ⅳ）的反萃变得困难。本文通过实验研究,获取了辐解产物与Pu（Ⅳ）保留的比例关系。结果表明,辐解产物磷酸二丁酯（HDBP）与羟胺（HAN）、稀硝酸难以反萃的Pu（Ⅳ）摩尔浓度之比约为2,磷酸一丁酯（H2MBP）与HAN难以反萃的Pu（Ⅳ）的摩尔浓度之比为1~2。结合文献报导,获取了不同辐解产物在PUREX流程中的产生量,从而较系统地比较了各辐解产物对Pu（Ⅳ）反萃的影响程度,并对主要辐解产物在PUREX流程中不同Pu（Ⅳ）反萃工艺段的影响进行了讨论。结果表明：热堆乏燃料后处理流程中对Pu（Ⅳ）反萃造成影响的主要辐解产物为HDBP,快堆乏燃料后处理流程中对Pu（Ⅳ）反萃造成影响的主要辐解产物为HDBP和H2MBP。 相似文献
10.
HAN Xiang 《等离子体科学和技术》2013,15(3):217-220
A 16-channel electron cyclotron emission (ECE) radiometer has been employed to observe the (m; n) = (2; 1) magnetic island structure on HT-7 tokamak, where m and n represent the poloidal and toroidal mode number respectively. The results indicate that the island width is about 7 cm when the magnetic island is saturated during the m=n = 2=1 mode. The location of resonance surface can be determined by plotting the contour of ECE relative fluctuation.This method could be applied to the HT-7 and EAST campaigns in the future for the research of neoclassical tearing modes (NTMs). 相似文献
11.
For the long-term fortification of warehoused crops, the insecticidal impact of cold plasma treated wheat seeds against red flour beetles are studied. In this study, the gain weight loss, mortality and repellency tests of cold plasma treated seeds are investigated and statistical analysis is carried out by SPSS software. Cold plasma treatment is carried out at 800 V for 1 and 4 min. The results show that the minimum grain weight loss is observed in plasma treated seeds as compared to controlled seeds. It is also observed that the mortality rate is minimum in the controlled seed while maximum at 4 min plasma treatment. Similarly, the repellent effect has a very small variation as compared to the controlled seed for Tribolium Castaneum. Therefore, plasma treatment can be considered as a practical and effective method for seed protection against red floor beetles particularly during long-term storage by controlling the insecticidal effects. 相似文献
12.
Gen CHEN 《等离子体科学和技术》2022,24(1):15602
The Ion Cyclotron Radio Frequency (ICRF) heating antenna on EAST adopts a decoupling device to constrain power coupling among the radiation straps, which was discovered shortcomings such as long size, poor contact, and etc. In order to improve these weak points, a new type decoupler with terminal-loaded tunable capacitor is designed to replace the previous design. Besides the capability of the tunable admittance parameters of decoupler, the withstand voltage of the capacitor is the most significant consideration for working under high power. Therefore, the theoretical analysis carefully elaborates the capacitor withstand voltage, and the detailed analytical equations and criteria for design are given. After the comparative analysis of theoretical calculation and 3D simulation results, the decoupler design scheme is finalized. The capacitor-loaded decoupler has been successfully adopted for ICRF antenna at port N on EAST, and achieved the optimization of adjacent port isolation from −22 to −58 dB at 37 MHz without plasma to restrict mutual coupling. The new design of the decoupler has greatly improved its compactness and automatic adjustment performance, and could be good solution for the decoupling network of ICRF antennas. 相似文献
13.
Ping WANG 《等离子体科学和技术》2022,24(7):75103
Lithium Beam Emission Spectroscopy systems in the outer midplane and divertor Langmuir probe arrays embedded in the divertor target plates, are utilized to investigate the scrape-off layer (SOL) blob transition and its relation with divertor detachment on EAST. The blob transition in the near SOL is observed during the density ramp-up phase. When the plasma density, normalized to the Greenwald density limit, exceeds a threshold of fGW ∼ 0.5, the blob size and lifetime increases by 2 – 3 times, while the blob detection rate decreases by about 2 times. In addition, a weak density shoulder is observed in the near SOL region at the same density threshold. Further analysis indicates that the divertor detachment is highly correlated with the blob transition, and the density threshold of blob transition is consistent with that of the access to the outer divertor detachment. The potential physical mechanisms are discussed. These results could be useful for the understanding of plasma-wall interaction issues in future devices that will operate under a detached divertor and high density conditions (over the blob transition threshold). 相似文献
14.
Wenjin CHEN 《等离子体科学和技术》2022,24(3):35101
Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the 'divertor-type' and 'limiter-type' free boundaries in the tokamak cylindrical coordinate. With a toroidal plasma flow, the flux functions are considerably different under the isentropic and isothermal assumptions. The effects of the toroidal flow on the magnetic axis shift are investigated. In a high beta plasma, the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a0 (a0 is the minor radius) for M0 = 0.2 (the toroidal Alfvén Mach number on the magnetic axis). In addition, the X-point is slightly shifted upward by 0.0125a0. But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M0 is usually less than 0.05 in a real tokamak. The effects of the toroidal flow on the plasma parameters are also investigated. The high toroidal flow shifts the plasma outward due to the centrifugal effect. Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case. 相似文献
15.
Huaxiang ZHANG 《等离子体科学和技术》2020,22(10):105102-105102
The property of scrape-off layer (SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell (PIC) simulations. A reduced Vlasov–Darwin model is employed, which is capable of describing the low-frequency kinetic behavior without electromagnetic vacuum modes A linear decay distribution of electron currents parallel to the background magnetic field is exhibited. Simulation analyses indicate that the cross field ion current is a key factor in sheath formation and global current balance. The influences of electrode area, biasing voltage and plasma source on the SOL current profile are studied, respectively. Characteristic plasma parameters in the far SOL region of the EAST tokamak are used in simulations to assess the current driving ability of the electrode biasing method. Due to the limitations of computational power, the geometrical size of the simulation domain is significantly smaller than the realistic SOL, which may lead to an absence of the quasi-neutral region in the upstream plasma. At last, a heuristic method is proposed to calculate the upper bound of the total current strength. 相似文献
16.
Doppler reflectometry is an important microwave diagnostic for turbulent fusion plasmas.A microwave beam is scattered off density fluctuations, with wavenumbers according to incident frequency and relative direction. This way, a density fluctuation spectrum is measured. However,the correspondence between fluctuation power and scattered microwave power is strongly nonlinear. Studying these processes numerically therefore requires fullwave simulations(IPF-FD3 D), with density fluctuations supplied by a separate plasma turbulence code(GENE).Earlier such attempts suffered from the low number of data points in the ‘interesting' part of the spectrum, where a power law had to be fitted to 4 or 5 points. This has been overcome with recent simulations, which now show a much better agreement with experimental data. 相似文献
17.
为了满足AP1000核电站设计寿命60年的需求,核岛设备蒸汽发生器锻件的强度和韧性要求比CPR1000核岛主设备都有所提高,加之尺寸增大,使得AP1000蒸汽发生器锻件的制造难度加大,对其变化认识不够,不仅锻件的产品质量不稳定,而且后序的焊接也可能出现质量问题,文章通过对比分析AP1000核电蒸汽发生器锻件与CPR1000锻件的变化,提出了采取措施的方向。 相似文献
18.
Research on the neutralization control of the RF ion micropropulsion system for the ‘Taiji-1’ satellite mission 
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下载免费PDF全文 Jianwu HE 《等离子体科学和技术》2020,22(9):94002-094002
To achieve the neutralization control requirements of the radio-frequency(RF) ion microthruster(μRIT) in the ‘Taiji-1' satellite mission, we proposed an active neutralization control solution that is based on the carbon nanotube field emission technology. The carbon nanotube field emission neutralizer(CNTN) has the characteristics of light weight, small size, and propellantless, which is especially suitable for the neutralization control tasks of ion microthrusters. The Institute of Mechanics, Chinese Academy of Sciences, in collaboration with Tsinghua University, has successfully developed a CNTN to meet mission requirements. On the ground, the feasibility of cooperation working between μRIT and CNTN was fully verified, as well as the simulation and experimental study of neutralization control strategy, which finally passed the engineering assessment test. Since the launch of ‘Taiji-1' satellite on 31 August,2019, the RF ion micropropulsion system has successfully completed nearly one hundred test missions in space. The test results indicate that CNTN does not have performance degradation,and the neutralization control strategy is effective. 相似文献
19.
It is shown that a steepening of the radial plasma pressure profile leads to a decrease in the critical value of beta, above which, small-scale balloon-type perturbations in a mirror trap become unstable. This may mean that small-scale ballooning instability leads to a smoothing of the radial plasma profile. The critical beta values for the real magnetic field of the gas-dynamic trap and various plasma pressure radial profiles was also calculated. For a plasma with a parabolic profile critical beta is evaluated at the level of 0.72. A previous theoretical prediction for this trap was almost two times lower than maximal beta 0.6 achieved experimentally. 相似文献
20.
Yunxiao WEI 《等离子体科学和技术》2020,22(12):125102-125102
The effect of background fluctuation on velocity diagnostics is discussed and studied. The kinetic theory of Mach probe (MP) and the theory of BGK mode are combined to evaluate how the measurement of MP is affected by electrostatics fluctuation. It is found that the quantity of speed by the MP model is closer to the effective velocity in the picture of momentum flux rather than the real mean velocity, while, with high fluctuation, the fitting parameter of MP's exponential formula should be corrected. 相似文献