Pub Date : 2023-12-21DOI: 10.1088/2058-6272/ad180e
Weisheng Cui, Ruobing Zhang
Atmospheric pressure cold plasma jets (APCPJs) typically exhibit a slender, conical structure, which imposes limitations on their application for surface modification due to the restricted treatment area. In this paper, we introduce a novel plasma jet morphology known as the large-scale cold plasma jet (LSCPJ), characterized by the presence of both a central conical plasma jet and a peripheral trumpet-like diffuse plasma jet. The experimental investigations have identified the factors influencing the conical and the trumpet-like diffuse plasma jet, and theoretical simulations have shed light on the role of the flow field and the electric field in shaping the formation of the LSCPJ. It is proved that, under conditions of elevated helium concentration, the distributions of impurity gas particles and the electric field jointly determine the plasma jet's morphology. High-speed ICCD camera images confirm the dynamic behavior of plasma bullets in LSCPJ, which is consistent with the theoretical analysis. Finally, it is demonstrated that when applied to the surface treatment of silicone rubber, LSCPJ can achieve a treatment area over 28 times larger than that of APCPJ under equivalent conditions. This paper uncovers the crucial role of impurity gases and electric fields in shaping plasma jet morphology and opens up the possibility of efficiently diversifying plasma jet generation effects through external electromagnetic fields. These insights hold the promise of reducing the generation cost of plasma jets and expanding their applications across various industrial sectors.
{"title":"A large-scale cold plasma jet: generation mechanism and application effect","authors":"Weisheng Cui, Ruobing Zhang","doi":"10.1088/2058-6272/ad180e","DOIUrl":"https://doi.org/10.1088/2058-6272/ad180e","url":null,"abstract":"\u0000 Atmospheric pressure cold plasma jets (APCPJs) typically exhibit a slender, conical structure, which imposes limitations on their application for surface modification due to the restricted treatment area. In this paper, we introduce a novel plasma jet morphology known as the large-scale cold plasma jet (LSCPJ), characterized by the presence of both a central conical plasma jet and a peripheral trumpet-like diffuse plasma jet. The experimental investigations have identified the factors influencing the conical and the trumpet-like diffuse plasma jet, and theoretical simulations have shed light on the role of the flow field and the electric field in shaping the formation of the LSCPJ. It is proved that, under conditions of elevated helium concentration, the distributions of impurity gas particles and the electric field jointly determine the plasma jet's morphology. High-speed ICCD camera images confirm the dynamic behavior of plasma bullets in LSCPJ, which is consistent with the theoretical analysis. Finally, it is demonstrated that when applied to the surface treatment of silicone rubber, LSCPJ can achieve a treatment area over 28 times larger than that of APCPJ under equivalent conditions. This paper uncovers the crucial role of impurity gases and electric fields in shaping plasma jet morphology and opens up the possibility of efficiently diversifying plasma jet generation effects through external electromagnetic fields. These insights hold the promise of reducing the generation cost of plasma jets and expanding their applications across various industrial sectors.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138951586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-20DOI: 10.1088/2058-6272/ad1792
Zhao Zhang, Ya-ju Li, Guanghui Yang, Qiang Zeng, Xiaolong Li, Liangwen Chen, D. Qian, Dui-xiong Sun, Maogen Su, Lei Yang, Shaofeng Zhang, Xinwen Ma
Recent work validated a new method for estimating grain size of microgranular materials in the range of tens-to-hundreds micrometers using laser-induced breakdown spectroscopy (LIBS). In that situation, univariate analysis was performed and a piecewise model has to be constructed for achieving the estimation of the grain size within such a wide range. This is due to the fact that a complex dependence of plasma formation environment (i.e., the status of luminous plasma and therefore LIBS signal to be measured) on grain size occurs in the size range studied there. In the present work, we tentatively construct a unified calibration model suitable for LIBS-based estimation of those grain sizes. Specifically, two unified multivariate calibration models are constructed based on back-propagation neural network (BPNN) algorithms using the feature selection strategies with and without considering physical prior knowledge, respectively. By detailed analysis of the performances of the two multivariate models, it was found that, a unified calibration model can be constructed successfully based on BPNN algorithms for estimating the grain size in the range of tens-to-hundreds micrometers. It was also found that this model constructed with a physics-guided feature selection strategy has better prediction performances. This study has practical significance in developing the technology for material analysis using LIBS, especially in the case that LIBS signal exhibits a complex dependence on the material parameter to be estimated.
{"title":"Estimating grain size of microgranular material using laser-induced breakdown spectroscopy combined with machine learning algorithms","authors":"Zhao Zhang, Ya-ju Li, Guanghui Yang, Qiang Zeng, Xiaolong Li, Liangwen Chen, D. Qian, Dui-xiong Sun, Maogen Su, Lei Yang, Shaofeng Zhang, Xinwen Ma","doi":"10.1088/2058-6272/ad1792","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1792","url":null,"abstract":"\u0000 Recent work validated a new method for estimating grain size of microgranular materials in the range of tens-to-hundreds micrometers using laser-induced breakdown spectroscopy (LIBS). In that situation, univariate analysis was performed and a piecewise model has to be constructed for achieving the estimation of the grain size within such a wide range. This is due to the fact that a complex dependence of plasma formation environment (i.e., the status of luminous plasma and therefore LIBS signal to be measured) on grain size occurs in the size range studied there. In the present work, we tentatively construct a unified calibration model suitable for LIBS-based estimation of those grain sizes. Specifically, two unified multivariate calibration models are constructed based on back-propagation neural network (BPNN) algorithms using the feature selection strategies with and without considering physical prior knowledge, respectively. By detailed analysis of the performances of the two multivariate models, it was found that, a unified calibration model can be constructed successfully based on BPNN algorithms for estimating the grain size in the range of tens-to-hundreds micrometers. It was also found that this model constructed with a physics-guided feature selection strategy has better prediction performances. This study has practical significance in developing the technology for material analysis using LIBS, especially in the case that LIBS signal exhibits a complex dependence on the material parameter to be estimated.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138958614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-17DOI: 10.1088/2058-6272/ad1676
Yue Ge, T. Xu, Chijie Xiao, Zhibin Guo, Xiaogang Wang, R. He, Xiaoyi Yang, Zuyu Zhang, Ruixin Yuan
The inward particle transport is associated with the formation of peaked density profiles, which contributes to improve the fusion rate and the realization of steady-state discharge. The active control of inward particle transport is considered as one of the most critical issues of magnetic confinement fusion. Recently, it is realized preliminarily by adding a biased endplate in the Peking University Plasma Test (PPT) device. The results reveal that the inward particle flux increases with the bias voltage of the endplate. It is also found that the profile of radial electric field (E_r) shear is flattened by the increased bias voltage. Radial velocity fluctuations (V_r) affect the inward particle more than density fluctuations. And the frequency of the dominant mode driving inward particle flux increases with the biased voltage applied to the endplate. The experimental results in the PPT device provide a method to actively control the inward particle flux actively using a biased endplate and enrich the understanding of the relationship between E_r×B shear and turbulence transport.
{"title":"Inward particle transport driven by biased endplate in a cylindrical magnetized plasma","authors":"Yue Ge, T. Xu, Chijie Xiao, Zhibin Guo, Xiaogang Wang, R. He, Xiaoyi Yang, Zuyu Zhang, Ruixin Yuan","doi":"10.1088/2058-6272/ad1676","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1676","url":null,"abstract":"\u0000 The inward particle transport is associated with the formation of peaked density profiles, which contributes to improve the fusion rate and the realization of steady-state discharge. The active control of inward particle transport is considered as one of the most critical issues of magnetic confinement fusion. Recently, it is realized preliminarily by adding a biased endplate in the Peking University Plasma Test (PPT) device. The results reveal that the inward particle flux increases with the bias voltage of the endplate. It is also found that the profile of radial electric field (E_r) shear is flattened by the increased bias voltage. Radial velocity fluctuations (V_r) affect the inward particle more than density fluctuations. And the frequency of the dominant mode driving inward particle flux increases with the biased voltage applied to the endplate. The experimental results in the PPT device provide a method to actively control the inward particle flux actively using a biased endplate and enrich the understanding of the relationship between E_r×B shear and turbulence transport.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-15DOI: 10.1088/2058-6272/ad162a
Yixuan Zhou, Yi Yu, Min Xu, Rui Ke, Lin Nie, Hao Xu, Guangyi Zhao, Hao Liu, Zihao Yuan, Chenyu Xiao, Jiquan Li, Chijie Xiao
An edge Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic, using a heating NBI (neutral beam injection) system, is currently under development on the HL-2A tokamak. The 20-channel edge LyBES, which is intended to measure the density fluctuation in plasma edge (from R = 1960 mm to R = 2026 mm) with an improved spatial resolution of 3.3 mm, is a complement to the existing conventional beam emission spectroscopy (BES) diagnostic. In this article, we introduce the progress of LyBES diagnostic, including the collection optics, the monochromator, and the detector system. The reflectance of the collection mirrors is measured to be ~82% at 122 nm, and the aberration geometrical radius of the collection optics is tested to be ~150 μm in the aimed area. The linear dispersion of the LyBES monochromator is designed to be ~0.09 nm mm−1. The bandwidth of the detector system with the 5×107 V A−1 preamplifier gain is measured to be ~280 kHz, and the peak-to-peak noise of the detector system is tested to be ~16 mV. The finalized design, components development and testing of the LyBES diagnostic have been completed at present, and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2A campaign.
{"title":"Progress of Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic on the HL-2A tokamak","authors":"Yixuan Zhou, Yi Yu, Min Xu, Rui Ke, Lin Nie, Hao Xu, Guangyi Zhao, Hao Liu, Zihao Yuan, Chenyu Xiao, Jiquan Li, Chijie Xiao","doi":"10.1088/2058-6272/ad162a","DOIUrl":"https://doi.org/10.1088/2058-6272/ad162a","url":null,"abstract":"\u0000 An edge Lyman-alpha-based beam emission spectroscopy (LyBES) diagnostic, using a heating NBI (neutral beam injection) system, is currently under development on the HL-2A tokamak. The 20-channel edge LyBES, which is intended to measure the density fluctuation in plasma edge (from R = 1960 mm to R = 2026 mm) with an improved spatial resolution of 3.3 mm, is a complement to the existing conventional beam emission spectroscopy (BES) diagnostic. In this article, we introduce the progress of LyBES diagnostic, including the collection optics, the monochromator, and the detector system. The reflectance of the collection mirrors is measured to be ~82% at 122 nm, and the aberration geometrical radius of the collection optics is tested to be ~150 μm in the aimed area. The linear dispersion of the LyBES monochromator is designed to be ~0.09 nm mm−1. The bandwidth of the detector system with the 5×107 V A−1 preamplifier gain is measured to be ~280 kHz, and the peak-to-peak noise of the detector system is tested to be ~16 mV. The finalized design, components development and testing of the LyBES diagnostic have been completed at present, and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2A campaign.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139000356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-14DOI: 10.1088/2058-6272/ad15df
Minyong Shen, Jibo Zhang, Yao Zhang, Y. Jie, Haiqing Liu, Jinlin Xie, Weixing Ding
Measurement of plasma electron density by far-infrared laser polarimetry has become a routine and indispensable tool in magnetic confinement fusion research. This article presents the design of a Cotton-Mouton polarimetric interferometer, which provides a reliable density measurement without fringe jumps. Cotton-Mouton effect on EAST is studied by Stokes equation with three parameters (s1, s2, s3). It demonstrates that under the condition of a small Cotton-Mouton effect, parameter s2 contains information about Cotton-Mouton effect which is proportional to the line-integrated density. For a typical EAST plasma, the magnitude of Cotton-Mouton effects is less than 2π for laser wavelength 432µm. Refractive effect due to density gradient is calculated to be negligible. Time modulation of Stokes parameters (s2, s3) provides heterodyne measurement. Due to the instabilities arising from laser oscillation and beam refraction in plasmas, it is necessary for the system to be insensitive to variations in the amplitude of the detection signal. Furthermore, it is shown that non-equal amplitude of X-mode and O-mode within a certain range only affects the DC offset of Stokes parameters (s2,s3) but does not greatly influence the phase measurements of Cotton-Mouton effects.
利用远红外激光偏振测量法测量等离子体电子密度已成为磁约束聚变研究中不可或缺的常规工具。本文介绍了 Cotton-Mouton 偏振干涉仪的设计，该干涉仪可提供可靠的密度测量，且不会出现条纹跳跃。通过斯托克斯方程研究了 Cotton-Mouton 对 EAST 的影响，该方程有三个参数（s1、s2、s3）。结果表明，在棉-木顿效应较小的条件下，参数 s2 包含棉-木顿效应的信息，该信息与线积分密度成正比。对于典型的 EAST 等离子体，在激光波长为 432µm 时，棉-木顿效应的大小小于 2π。根据计算，密度梯度引起的折射效应可以忽略不计。斯托克斯参数（s2、s3）的时间调制提供了外差测量。由于等离子体中激光振荡和光束折射产生的不稳定性，系统必须对探测信号的振幅变化不敏感。此外，研究还表明，在一定范围内 X 模式和 O 模式的振幅不相等只会影响斯托克斯参数（s2,s3）的直流偏移，而不会对 Cotton-Mouton 效应的相位测量产生很大影响。
{"title":"Forward modelling of the Cotton-Mouton effect polarimetry on EAST tokamak","authors":"Minyong Shen, Jibo Zhang, Yao Zhang, Y. Jie, Haiqing Liu, Jinlin Xie, Weixing Ding","doi":"10.1088/2058-6272/ad15df","DOIUrl":"https://doi.org/10.1088/2058-6272/ad15df","url":null,"abstract":"\u0000 Measurement of plasma electron density by far-infrared laser polarimetry has become a routine and indispensable tool in magnetic confinement fusion research. This article presents the design of a Cotton-Mouton polarimetric interferometer, which provides a reliable density measurement without fringe jumps. Cotton-Mouton effect on EAST is studied by Stokes equation with three parameters (s1, s2, s3). It demonstrates that under the condition of a small Cotton-Mouton effect, parameter s2 contains information about Cotton-Mouton effect which is proportional to the line-integrated density. For a typical EAST plasma, the magnitude of Cotton-Mouton effects is less than 2π for laser wavelength 432µm. Refractive effect due to density gradient is calculated to be negligible. Time modulation of Stokes parameters (s2, s3) provides heterodyne measurement. Due to the instabilities arising from laser oscillation and beam refraction in plasmas, it is necessary for the system to be insensitive to variations in the amplitude of the detection signal. Furthermore, it is shown that non-equal amplitude of X-mode and O-mode within a certain range only affects the DC offset of Stokes parameters (s2,s3) but does not greatly influence the phase measurements of Cotton-Mouton effects.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139001523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-14DOI: 10.1088/2058-6272/ad15e0
Tao Wang, S. Wei, S. Briguglio, G. Vlad, F. Zonca, Zhiyong Qiu
In a tokamak fusion reactor operated at steady state, the equilibrium magnetic field is likely to have reversed shear in the core region, as the noninductive bootstrap current profile generally peaks off-axis. The reversed shear Alfvén eigenmode (RSAE) as a unique branch of the shear Alfvén wave in this equilibrium, can exist with a broad spectrum in wavenumber and frequency, and be resonantly driven unstable by energetic particles (EP). After briefly discussing the RSAE linear properties in burning plasma condition, we review several key topics of the nonlinear dynamics for the RSAE through both wave-EP resonance and wave-wave coupling channels, and illustrate their potentially important role in reactor-scale fusion plasmas. By means of simplified hybrid MHD-kinetic simulations, the RSAEs are shown to have typically broad phase space resonance structure with both circulating and trapped EP, as results of weak/vanishing magnetic shear and relatively low frequency. Through the route of wave-EP nonlinearity, the dominant saturation mechanism is mainly due to the transported resonant EP radially decoupling with the localized RSAE mode structure, and the resultant EP transport generally has a convective feature. The saturated RSAEs also undergo various nonlinear couplings with other collective oscillations. Two typical routes as parametric decay and modulational instability are studied using nonlinear gyrokinetic theory, and applied to the scenario of spontaneous excitation by a finite amplitude pump RSAE. Multiple RSAEs could naturally couple and induce the spectral energy cascade into a low frequency Alfvénic mode, which may effectively transfer the EP energy to fuel ions via collisionless Landau damping. Moreover, zero frequency zonal field structure could be spontaneously excited by modulation of the pump RSAE envelope, and may also lead to saturation of the pump RSAE by both scattering into stable domain and local distortion of the continuum structure.
在稳态运行的托卡马克聚变反应堆中，平衡磁场很可能在堆芯区域具有反向剪切力，因为非感应自举电流曲线通常在轴外达到峰值。反向剪切阿尔弗文特征模（RSAE）作为这种平衡状态下剪切阿尔弗文波的一个独特分支，可以以宽广的波数和频率频谱存在，并受到高能粒子（EP）的共振驱动而不稳定。在简要讨论了燃烧等离子体条件下 RSAE 的线性特性之后，我们通过波-EP 共振和波-波耦合通道回顾了 RSAE 非线性动力学的几个关键主题，并说明了它们在反应堆尺度聚变等离子体中的潜在重要作用。通过简化的混合 MHD 动力学模拟，RSAE 具有典型的宽相空间共振结构，既有循环 EP，也有捕获 EP，这是弱/渐弱磁剪切和相对较低频率的结果。通过波-EP 非线性途径，主导饱和机制主要是由于传输的共振 EP 与局部 RSAE 模式结构径向解耦，由此产生的 EP 传输一般具有对流特征。饱和的 RSAE 还会与其他集体振荡发生各种非线性耦合。我们利用非线性陀螺动理论研究了参数衰减和调制不稳定性这两种典型途径，并将其应用于有限振幅泵 RSAE 自发激发的情况。多个 RSAE 可以自然耦合并诱导频谱能量级联到低频阿尔费尼科模式，该模式可以通过无碰撞朗道阻尼有效地将 EP 能量转移到燃料离子上。此外，零频率带状场结构可通过调制泵 RSAE 包络而自发激发，也可能通过散射到稳定域和连续结构的局部畸变而导致泵 RSAE 饱和。
{"title":"Nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas","authors":"Tao Wang, S. Wei, S. Briguglio, G. Vlad, F. Zonca, Zhiyong Qiu","doi":"10.1088/2058-6272/ad15e0","DOIUrl":"https://doi.org/10.1088/2058-6272/ad15e0","url":null,"abstract":"\u0000 In a tokamak fusion reactor operated at steady state, the equilibrium magnetic field is likely to have reversed shear in the core region, as the noninductive bootstrap current profile generally peaks off-axis. The reversed shear Alfvén eigenmode (RSAE) as a unique branch of the shear Alfvén wave in this equilibrium, can exist with a broad spectrum in wavenumber and frequency, and be resonantly driven unstable by energetic particles (EP). After briefly discussing the RSAE linear properties in burning plasma condition, we review several key topics of the nonlinear dynamics for the RSAE through both wave-EP resonance and wave-wave coupling channels, and illustrate their potentially important role in reactor-scale fusion plasmas. By means of simplified hybrid MHD-kinetic simulations, the RSAEs are shown to have typically broad phase space resonance structure with both circulating and trapped EP, as results of weak/vanishing magnetic shear and relatively low frequency. Through the route of wave-EP nonlinearity, the dominant saturation mechanism is mainly due to the transported resonant EP radially decoupling with the localized RSAE mode structure, and the resultant EP transport generally has a convective feature. The saturated RSAEs also undergo various nonlinear couplings with other collective oscillations. Two typical routes as parametric decay and modulational instability are studied using nonlinear gyrokinetic theory, and applied to the scenario of spontaneous excitation by a finite amplitude pump RSAE. Multiple RSAEs could naturally couple and induce the spectral energy cascade into a low frequency Alfvénic mode, which may effectively transfer the EP energy to fuel ions via collisionless Landau damping. Moreover, zero frequency zonal field structure could be spontaneously excited by modulation of the pump RSAE envelope, and may also lead to saturation of the pump RSAE by both scattering into stable domain and local distortion of the continuum structure.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138973901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Only a small amount of spectral information is collected because the collection solid angle of the optical fiber probe and lens is very limited，when collecting spectral information. To overcome this limitation, this study presents a novel method for acquiring plasma spectral information from various spatial directions. A parabolic-shaped plasma spectral collection device(PSCD) is employed to effectively collect more spectral information into the spectrometer, thereby enhancing the overall spectral intensity. The research objects in this study were soil samples containing different concentrations of heavy metals Pb, Cr, and Cd. The results indicate that the PSCD significantly enhances the spectral signal, with an enhancement rate of up to 45%. Moreover, the signal-to-noise ratio also increases by as much as 36%. Simultaneously, when compared to the absence of a device, it is found that there is no significant variation in plasma temperature when the PSCD is utilized. This observation eliminates the impact of the spatial effect caused by the PSCD on the spectral intensity. Consequently, a concentration-spectral intensity relationship curve is established under the PSCD. The results revealed that the linear fitting R2 for Pb, Cr, and Cd increased by 0.011, 0.001, and 0.054, respectively. Additionally, the limit of detection (LOD) decreased by 0.361 ppm, 0.901 ppm, and 0.602 ppm, respectively. These findings indicate that the spectral enhancement rate elevates with the increase in heavy metal concentration. Hence, the PSCD can effectively enhance the spectral intensity and reduce the detection limit of heavy metals in soil.
{"title":"A research on the effect of plasma spectrum collection device on LIBS spectral intensity","authors":"Xiaomei Lin, Yanjie Dong, Jingjun Lin, Yutao Huang, Jiangfei Yang, Xingyu Yue, Zhuojia Zhang, Xinyang Duan","doi":"10.1088/2058-6272/ad15e1","DOIUrl":"https://doi.org/10.1088/2058-6272/ad15e1","url":null,"abstract":"\u0000 Only a small amount of spectral information is collected because the collection solid angle of the optical fiber probe and lens is very limited，when collecting spectral information. To overcome this limitation, this study presents a novel method for acquiring plasma spectral information from various spatial directions. A parabolic-shaped plasma spectral collection device(PSCD) is employed to effectively collect more spectral information into the spectrometer, thereby enhancing the overall spectral intensity. The research objects in this study were soil samples containing different concentrations of heavy metals Pb, Cr, and Cd. The results indicate that the PSCD significantly enhances the spectral signal, with an enhancement rate of up to 45%. Moreover, the signal-to-noise ratio also increases by as much as 36%. Simultaneously, when compared to the absence of a device, it is found that there is no significant variation in plasma temperature when the PSCD is utilized. This observation eliminates the impact of the spatial effect caused by the PSCD on the spectral intensity. Consequently, a concentration-spectral intensity relationship curve is established under the PSCD. The results revealed that the linear fitting R2 for Pb, Cr, and Cd increased by 0.011, 0.001, and 0.054, respectively. Additionally, the limit of detection (LOD) decreased by 0.361 ppm, 0.901 ppm, and 0.602 ppm, respectively. These findings indicate that the spectral enhancement rate elevates with the increase in heavy metal concentration. Hence, the PSCD can effectively enhance the spectral intensity and reduce the detection limit of heavy metals in soil.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138975529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-13DOI: 10.1088/2058-6272/ad1572
Baoyong Ren, Shiyu Fang, Tiantian Zhang, Yan Sun, Erhao Gao, Jing Li, Zu-liang Wu, Jiali Zhu, Wei Wang, S. Yao
Diesel particulate matter (DPM) and hydrocarbons (HC) emitted from diesel engines negatively affect air quality and human health. Catalysts for oxidative removals of DPM and HC are currently used universally but the low removal efficiency at low temperatures is a problem. In this study, Cu-doped CeO2 loaded on Al2O3 coupled with plasma was used to enhance DPM and HC low-temperature oxidation. DPM and HC removals at 200 °C using the catalyst were as high as 90% with plasma, while below 30% without plasma. Operando plasma DRIFTS-MS was conducted to reveal the function mechanism of the oxygen species on DPM oxidation process. It was found that Cu-CeO2 can promote the formation of adsorbed oxygen (M+-O2 − ) and terminal oxygen (M=O), which can react with DPM to form carbonates that are easily converted to gaseous CO2. Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HC at low temperatures.
柴油发动机排放的柴油微粒物质（DPM）和碳氢化合物（HC）对空气质量和人类健康产生了负面影响。目前，用于氧化去除 DPM 和 HC 的催化剂已被普遍使用，但在低温条件下去除效率较低是一个问题。在这项研究中，采用等离子体在 Al2O3 上负载掺铜 CeO2 来增强 DPM 和 HC 的低温氧化作用。在 200 °C 温度下，使用该催化剂的 DPM 和 HC 去除率在有等离子体的情况下高达 90%，而在无等离子体的情况下则低于 30%。为了揭示氧物种在 DPM 氧化过程中的作用机理，进行了操作等离子体 DRIFTS-MS 分析。研究发现，Cu-CeO2 能促进吸附氧（M+-O2 - ）和末端氧（M=O）的形成，这些氧能与 DPM 反应生成碳酸盐，而碳酸盐很容易转化为气态 CO2。我们的研究结果提供了一种实用的等离子催化技术，可在低温下同时去除 DPM 和 HC。
{"title":"Efficient simultaneous removal of DPM and HC from diesel exhaust gas at low temperatures over Cu-CeO2/Al2O3 coupling with DBD plasma","authors":"Baoyong Ren, Shiyu Fang, Tiantian Zhang, Yan Sun, Erhao Gao, Jing Li, Zu-liang Wu, Jiali Zhu, Wei Wang, S. Yao","doi":"10.1088/2058-6272/ad1572","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1572","url":null,"abstract":"\u0000 Diesel particulate matter (DPM) and hydrocarbons (HC) emitted from diesel engines negatively affect air quality and human health. Catalysts for oxidative removals of DPM and HC are currently used universally but the low removal efficiency at low temperatures is a problem. In this study, Cu-doped CeO2 loaded on Al2O3 coupled with plasma was used to enhance DPM and HC low-temperature oxidation. DPM and HC removals at 200 °C using the catalyst were as high as 90% with plasma, while below 30% without plasma. Operando plasma DRIFTS-MS was conducted to reveal the function mechanism of the oxygen species on DPM oxidation process. It was found that Cu-CeO2 can promote the formation of adsorbed oxygen (M+-O2\u0000 − ) and terminal oxygen (M=O), which can react with DPM to form carbonates that are easily converted to gaseous CO2. Our results provide a practical plasma catalysis technology to obtain simultaneous removals of DPM and HC at low temperatures.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139004779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-13DOI: 10.1088/2058-6272/ad1571
Jianqing Cai, Yunfeng Liang, Alexander Knieps, dongkai qi, Erhui Wang, Haoming Xiang, Liang Liao, Jie Huang, Jie Yang, Jia Huang, Jianwen Liu, P. Drews, Shuai Xu, xiang gu, Yichen Gao, Yu Luo, zhi li
A neural network model with classical annotation method has been used on EXL-50 tokamak to predict the impending disruptions. However, the results revealed issues of overfitting and overconfidence in predictions caused by the inaccurate labeling. To mitigate these issues, an improved training framework has been proposed. In this approach, soft labels from previous training serve as teachers to supervise the further learning process, which has demonstrated its significant improvement in predictive model performance. Notably, this enhancement is primarily attributed to the coupling effect of the soft labels and correction mechanism. This improved training framework introduces an instance-specific label smoothing method, which reflects a more nuanced model’s assessment on the likelihood of a disruption. It presents a possible solution to effectively address the challenges associated with accurate labeling across different machines
{"title":"An improved training framework in neural network model fordisruption prediction and its application on EXL-50","authors":"Jianqing Cai, Yunfeng Liang, Alexander Knieps, dongkai qi, Erhui Wang, Haoming Xiang, Liang Liao, Jie Huang, Jie Yang, Jia Huang, Jianwen Liu, P. Drews, Shuai Xu, xiang gu, Yichen Gao, Yu Luo, zhi li","doi":"10.1088/2058-6272/ad1571","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1571","url":null,"abstract":"\u0000 A neural network model with classical annotation method has been used on EXL-50 tokamak to predict the impending disruptions. However, the results revealed issues of overfitting and overconfidence in predictions caused by the inaccurate labeling. To mitigate these issues, an improved training framework has been proposed. In this approach, soft labels from previous training serve as teachers to supervise the further learning process, which has demonstrated its significant improvement in predictive model performance. Notably, this enhancement is primarily attributed to the coupling effect of the soft labels and correction mechanism. This improved training framework introduces an instance-specific label smoothing method, which reflects a more nuanced model’s assessment on the likelihood of a disruption. It presents a possible solution to effectively address the challenges associated with accurate labeling across different machines","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139005390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Ultrasonic Electric Propulsion (UEP) system is a cutting-edge propulsion technology that is mostly used on platforms for small satellites (less than 10 kg). The characteristics of droplet partial emissions (DPEs) in the UEP system are investigated using a high-speed imaging technique (an ultra-high speed camera (NAC HX-6) and a long-distance microscope) in this work. The experiments demonstrate that there are a few partial emission modes, including left-side emission, double-side emission, and right-side emission, that are present in the droplet emission process of the UEP system. These modes are primarily caused by the partial formation of capillary standing waves (CSWs) on the emission surface of the ultrasonic nozzle. The emission rate for single- and double-sided emissions varies at different times, indicating that there are different CSWs engaged in droplet emission due to variations in the liquid film thickness and charge state of the liquid cones. Additionally, as the droplets emit continuously, a raised area on the emission surface appears, with several droplets emitting there as a result of charge accumulation. Additionally, photos of the CSWs with emitting droplets are obtained, which highlights the CSWs’ distinctive wave morphology.
{"title":"Preliminary study of the electrospray DPE peculiarities from the liquid surface in the presence of the CSWs","authors":"Weiguo He, Weijie Huo, Luofeng Han, Kangwu Zhu, Feng Wang, Zekun Wang","doi":"10.1088/2058-6272/ad1570","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1570","url":null,"abstract":"\u0000 The Ultrasonic Electric Propulsion (UEP) system is a cutting-edge propulsion technology that is mostly used on platforms for small satellites (less than 10 kg). The characteristics of droplet partial emissions (DPEs) in the UEP system are investigated using a high-speed imaging technique (an ultra-high speed camera (NAC HX-6) and a long-distance microscope) in this work. The experiments demonstrate that there are a few partial emission modes, including left-side emission, double-side emission, and right-side emission, that are present in the droplet emission process of the UEP system. These modes are primarily caused by the partial formation of capillary standing waves (CSWs) on the emission surface of the ultrasonic nozzle. The emission rate for single- and double-sided emissions varies at different times, indicating that there are different CSWs engaged in droplet emission due to variations in the liquid film thickness and charge state of the liquid cones. Additionally, as the droplets emit continuously, a raised area on the emission surface appears, with several droplets emitting there as a result of charge accumulation. Additionally, photos of the CSWs with emitting droplets are obtained, which highlights the CSWs’ distinctive wave morphology.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139005760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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