Pub Date : 2024-01-11DOI: 10.1088/2058-6272/ad1db4
Na Li, Lisong Zhang, Xiaonan Zhang, Liyue Gong, Jianbing Qiang, X. Mei
In this paper, high-energy Ne ions were used to irradiate Zr63.5Cu23Al9Fe4.5 MG and crystalline W to investigate their difference in mechanical response after irradiation. The results showed that with the irradiation dose increased, the tensile micro-strain increased, nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa, Young's modulus increased, and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W. Under the same irradiation conditions, the Zr63.5Cu23Al9Fe4.5 MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr63.5Cu23Al9Fe4.5 MG than in crystalline W. Unlike the irradiation hardening and embrittlement behavior of crystalline W, Zr63.5Cu23Al9Fe4.5 MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa, the decrease in modulus and the increase in plastic deformability with the increasing dose. Possibly, the irradiation softening and toughening phenomenon of Zr63.5Cu23Al9Fe4.5 MG could provide new ideas for the design of nuclear materials.
本文采用高能Ne离子辐照Zr63.5Cu23Al9Fe4.5 MG和晶体W，研究它们在辐照后的力学响应差异。结果表明，随着辐照剂量的增加，拉伸微应变增加，纳米硬度从 7.11 GPa 增加到 7.90 GPa 和 8.62 GPa，杨氏模量增加，H3/E2 增加，这表明晶体 W 的塑性变形能力下降。5 MG 仍保持无定形结构，尽管与晶体 W 相比，Zr63.5Cu23Al9Fe4.5 MG 中 Ne 离子的位移范围更长、位移损伤更强，但其变得更加无序。与晶体 W 的辐照硬化和脆化行为不同，随着剂量的增加，Zr63.5Cu23Al9Fe4.5 MG 的硬度从 6.02 GPa 逐渐降低到 5.89 GPa 和 5.50 GPa，模量降低，塑性变形能力增加。Zr63.5Cu23Al9Fe4.5 MG的辐照软化和增韧现象可能为核材料的设计提供了新思路。
{"title":"Effect of high-energy Ne ions irradiation on mechanical properties difference between Zr63.5Cu23Al9Fe4.5 metallic glass and crystalline W","authors":"Na Li, Lisong Zhang, Xiaonan Zhang, Liyue Gong, Jianbing Qiang, X. Mei","doi":"10.1088/2058-6272/ad1db4","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1db4","url":null,"abstract":"\u0000 In this paper, high-energy Ne ions were used to irradiate Zr63.5Cu23Al9Fe4.5 MG and crystalline W to investigate their difference in mechanical response after irradiation. The results showed that with the irradiation dose increased, the tensile micro-strain increased, nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa, Young's modulus increased, and H3/E2 increased which indicating that the plastic deformability decreased in crystalline W. Under the same irradiation conditions, the Zr63.5Cu23Al9Fe4.5 MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr63.5Cu23Al9Fe4.5 MG than in crystalline W. Unlike the irradiation hardening and embrittlement behavior of crystalline W, Zr63.5Cu23Al9Fe4.5 MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa, the decrease in modulus and the increase in plastic deformability with the increasing dose. Possibly, the irradiation softening and toughening phenomenon of Zr63.5Cu23Al9Fe4.5 MG could provide new ideas for the design of nuclear materials.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139438467","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 : 2024-01-09DOI: 10.1088/2058-6272/ad1c76
Weice Wang, Jun Cheng, Zhongbing Shi, Longwen Yan, Zhihui Huang, K. Yi, Na Wu, Yu He, Q. Zou, Xi Chen, Wen Zhang, Jian Chen, Lin Nie, Xiaoquan Ji, Wulyu Zhong
This paper reports an improved time-delay displacement estimation (TDE) technique for the derivation of turbulence structures based on gas-puff imaging (GPI) data. The improved TDE technique, integrating an inverse timing search and hierarchical strategy, offers superior accuracy in calculating turbulent velocity field maps and analyzing blob dynamics, which has power to obtain the radial profiles of equilibrium poloidal velocity, blob size and its radial velocity, even the fluctuation analysis, such as geodesic acoustic modes (GAM) and quasi-coherent mode (QCM), etc. This improved technique could provide important 2D information for the study of edge turbulence and the blob dynamics, advancing the understanding of edge turbulence physics in fusion plasmas.
{"title":"An improved TDE technique for derivation of 2D turbulence structures based on GPI data in toroidal plasma","authors":"Weice Wang, Jun Cheng, Zhongbing Shi, Longwen Yan, Zhihui Huang, K. Yi, Na Wu, Yu He, Q. Zou, Xi Chen, Wen Zhang, Jian Chen, Lin Nie, Xiaoquan Ji, Wulyu Zhong","doi":"10.1088/2058-6272/ad1c76","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1c76","url":null,"abstract":"\u0000 This paper reports an improved time-delay displacement estimation (TDE) technique for the derivation of turbulence structures based on gas-puff imaging (GPI) data. The improved TDE technique, integrating an inverse timing search and hierarchical strategy, offers superior accuracy in calculating turbulent velocity field maps and analyzing blob dynamics, which has power to obtain the radial profiles of equilibrium poloidal velocity, blob size and its radial velocity, even the fluctuation analysis, such as geodesic acoustic modes (GAM) and quasi-coherent mode (QCM), etc. This improved technique could provide important 2D information for the study of edge turbulence and the blob dynamics, advancing the understanding of edge turbulence physics in fusion plasmas.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442042","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 : 2024-01-08DOI: 10.1088/2058-6272/ad1c38
Yilin Li, H. Liao, Haiyang Zhou, Xuan Sun
Field Reversed Configuration (FRC) is widely considered as an ideal target plasma for magneto-inertial fusion. However, its confinement and stability, both proportional to the radius, will deteriorate inevitably during radial compression. Hence, we propose a new fusion approach based on axial compression of a large-sized FRC. The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC. The parameter space that can reach the ignition condition while preserve the FRC’s overall quality is studied by using a numerical model based on different FRC confinement scaling. It is found that ignition is possible for large FRC that can be achieved with the current FRC formation techniques if compression ratio is larger than 50. A more realistic compression is to combine axial with moderate radial compression, which is also presented and calculated in this work.
{"title":"A numerical survey of parameters to reach ignition condition for axial compression of a large-sized field reversed configuration (FRC)","authors":"Yilin Li, H. Liao, Haiyang Zhou, Xuan Sun","doi":"10.1088/2058-6272/ad1c38","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1c38","url":null,"abstract":"\u0000 Field Reversed Configuration (FRC) is widely considered as an ideal target plasma for magneto-inertial fusion. However, its confinement and stability, both proportional to the radius, will deteriorate inevitably during radial compression. Hence, we propose a new fusion approach based on axial compression of a large-sized FRC. The axial compression can be made by plasma jets or plasmoids converging onto the axial ends of the FRC. The parameter space that can reach the ignition condition while preserve the FRC’s overall quality is studied by using a numerical model based on different FRC confinement scaling. It is found that ignition is possible for large FRC that can be achieved with the current FRC formation techniques if compression ratio is larger than 50. A more realistic compression is to combine axial with moderate radial compression, which is also presented and calculated in this work.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139445790","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 effects of equilibrium toroidal rotation during edge-localized mode (ELM) mitigated by resonant magnetic perturbation (RMP) are studied with the experimental equilibria of the EAST tokamak based on the four-field model in the BOUT++ code. As the two main parameters to determine the toroidal rotation profiles, the rotation shear and magnitudes were separately scanned to investigate their roles in the impact of RMPs on peeling–ballooning (P-B) modes. On one hand, the results show that strong toroidal rotation shear is favorable for the enhancement of the self-generated shearing rate with RMPs, leading to significant ELM mitigation with RMP in the stronger toroidal rotation shear region. On the other hand, toroidal rotation magnitudes may affect ELM mitigation by changing the penetration of the RMPs, more precisely the resonant components. RMPs can lead to a reduction in the pedestal energy loss by enhancing the multimode coupling in the turbulence transport phase. The shielding effects on RMPs increase with the toroidal rotation magnitude, leading to the enhancement of the multimode coupling with RMPs to be significantly weakened. Hence, the reduction in pedestal energy loss by RMPs decreased with the rotation magnitude. In brief, the results show that toroidal rotation plays a dual role in ELM mitigation with RMP by changing the shielding effects of plasma by rotation magnitude and affecting by rotation shear. In the high toroidal rotation region, toroidal rotation shear is usually strong and hence plays a dominant role in the influence of RMP on P-B modes, whereas in the low rotation region, toroidal rotation shear is weak and has negligible impact on P-B modes, and the rotation magnitude plays a dominant role in the influence of RMPs on the P-B modes by changing the field penetration. Therefore, the dual role of toroidal rotation leads to stronger ELM mitigation with RMP, which may be achieved both in the low toroidal rotation region and the relatively high rotation region that has strong rotational shear.
基于 BOUT++ 代码中的四场模型，利用 EAST 托卡马克的实验平衡，研究了共振磁扰动（RMP）缓解边缘局部模式（ELM）期间平衡环形旋转的影响。作为决定环形旋转剖面的两个主要参数，旋转剪切力和幅度被分别扫描，以研究它们在共振磁扰动对剥离-膨胀（P-B）模式的影响中的作用。结果表明，一方面，强环形旋转剪切力有利于提高 RMP 的自生剪切率，从而在强环形旋转剪切力区域内通过 RMP 显著减缓 ELM。另一方面，环形旋转幅度可能会通过改变 RMP 的穿透力（更确切地说是共振成分）来影响 ELM 减缓效果。RMP 可通过增强湍流传输阶段的多模耦合来减少基座能量损失。RMP 的屏蔽效应随环形旋转幅度的增加而增加，导致 RMP 的多模耦合增强作用明显减弱。因此，RMP 的基座能量损失随旋转幅度的增加而减少。简而言之，研究结果表明，环形旋转通过旋转幅度改变等离子体的屏蔽效应，并通过旋转剪切力影响等离子体的屏蔽效应，在利用 RMP 缓解 ELM 方面发挥着双重作用。在高环形旋转区域，环形旋转剪切通常很强，因此在 RMP 对 P-B 模式的影响中起主导作用；而在低旋转区域，环形旋转剪切很弱，对 P-B 模式的影响可以忽略不计，而旋转幅度则通过改变场穿透力在 RMP 对 P-B 模式的影响中起主导作用。因此，环面旋转的双重作用导致 RMP 对 ELM 的缓解作用更强，这在低环面旋转区域和具有强旋转剪切力的相对高旋转区域均可实现。
{"title":"Investigation on the roles of equilibrium toroidal rotation during edge-localized mode mitigated by resonant magnetic perturbations","authors":"Liangkang DONG, Shaoyong CHEN, Maolin MOU, Yang LUO, Chenchen QIN, Changjian TANG","doi":"10.1088/2058-6272/ad0d4d","DOIUrl":"https://doi.org/10.1088/2058-6272/ad0d4d","url":null,"abstract":"The effects of equilibrium toroidal rotation during edge-localized mode (ELM) mitigated by resonant magnetic perturbation (RMP) are studied with the experimental equilibria of the EAST tokamak based on the four-field model in the BOUT++ code. As the two main parameters to determine the toroidal rotation profiles, the rotation shear and magnitudes were separately scanned to investigate their roles in the impact of RMPs on peeling–ballooning (P-B) modes. On one hand, the results show that strong toroidal rotation shear is favorable for the enhancement of the self-generated <inline-formula>\u0000<tex-math><?CDATA $ boldsymbol{E}times boldsymbol{B} $?></tex-math>\u0000<inline-graphic xlink:href=\"pst_26_1_015102_M1.jpg\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> shearing rate <inline-formula>\u0000<tex-math><?CDATA $ leftlangle{{omega }_{boldsymbol{E}times boldsymbol{B}}}rightrangle $?></tex-math>\u0000<inline-graphic xlink:href=\"pst_26_1_015102_M2.jpg\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> with RMPs, leading to significant ELM mitigation with RMP in the stronger toroidal rotation shear region. On the other hand, toroidal rotation magnitudes may affect ELM mitigation by changing the penetration of the RMPs, more precisely the resonant components. RMPs can lead to a reduction in the pedestal energy loss by enhancing the multimode coupling in the turbulence transport phase. The shielding effects on RMPs increase with the toroidal rotation magnitude, leading to the enhancement of the multimode coupling with RMPs to be significantly weakened. Hence, the reduction in pedestal energy loss by RMPs decreased with the rotation magnitude. In brief, the results show that toroidal rotation plays a dual role in ELM mitigation with RMP by changing the shielding effects of plasma by rotation magnitude and affecting <inline-formula>\u0000<tex-math><?CDATA $ leftlangle{{omega }_{boldsymbol{E}times boldsymbol{B}}}rightrangle $?></tex-math>\u0000<inline-graphic xlink:href=\"pst_26_1_015102_M3.jpg\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> by rotation shear. In the high toroidal rotation region, toroidal rotation shear is usually strong and hence plays a dominant role in the influence of RMP on P-B modes, whereas in the low rotation region, toroidal rotation shear is weak and has negligible impact on P-B modes, and the rotation magnitude plays a dominant role in the influence of RMPs on the P-B modes by changing the field penetration. Therefore, the dual role of toroidal rotation leads to stronger ELM mitigation with RMP, which may be achieved both in the low toroidal rotation region and the relatively high rotation region that has strong rotational shear.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139093691","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 : 2024-01-01DOI: 10.1088/2058-6272/ad0d47
Shujaht BUKHARI, Muhammad SHAHID, Ata-ur RAHMAN
The ion-acoustic (IA) mode exhibiting various orbital angular momentum (OAM) states is examined in a plasma with drifting electrons. The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented. In the domain of kinetic model, the twisted IA waves are characterized by Laguerre-Gaussian (LG) solutions, where plasma distribution function and electric field are decomposed into axial and azimuthal components. The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures. The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.
研究了在具有漂移电子的等离子体中表现出各种轨道角动量（OAM）状态的离子声（IA）模式。等离子体的组成物质采用非熵麦克斯韦分布建模，并讨论了各种条件下扭曲 IA 波的弥散关系和增长率。在动力学模型领域，扭曲 IA 波以拉盖尔-高斯（LG）解为特征，等离子体分布函数和电场被分解为轴向和方位角分量。等离子体响应函数是在准轴向近似条件下获得的，并研究了螺旋电场结构的不稳定增长率阈值条件。通过比较单电子和双电子的扭曲波，证明了额外电子对不稳定性的影响。
{"title":"Ion-acoustic waves with non-planar wavefronts","authors":"Shujaht BUKHARI, Muhammad SHAHID, Ata-ur RAHMAN","doi":"10.1088/2058-6272/ad0d47","DOIUrl":"https://doi.org/10.1088/2058-6272/ad0d47","url":null,"abstract":"The ion-acoustic (IA) mode exhibiting various orbital angular momentum (OAM) states is examined in a plasma with drifting electrons. The constituent plasma species are modeled with a non-gyrotropic Maxwellian distribution and discussion of dispersion relation and growth rate of twisted IA waves under various conditions is presented. In the domain of kinetic model, the twisted IA waves are characterized by Laguerre-Gaussian (LG) solutions, where plasma distribution function and electric field are decomposed into axial and azimuthal components. The plasma response function is obtained under paraxial approximations and investigated for threshold condition of instability growth rate with helical electric field structures. The impact of an extra electron specie on the instability is demonstrated through a comparison of twisted waves for single and double electron species.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139093651","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 : 2024-01-01DOI: 10.1088/2058-6272/ad0d57
Feng WANG, Jiquan LI, Hongpeng QU, Xiaodong PENG
Ion temperature gradient (ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code (GKNET) in this work. Different from the traditional equilibrium circular magnetic-surface average (EMSA) method, an advanced algorithm that calculates the perturbed magnetic-surface average (PMSA) of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands. Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method. It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient, i.e. the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm. The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear. Such an electric potential vortex mode may be of essential importance in wide topics, such as the turbulence spreading across magnetic islands, neoclassical tearing mode physics, and also the interaction dynamics between the micro-turbulence and MHD activities.
{"title":"Gyrokinetic simulation of magnetic-island-induced electric potential vortex mode","authors":"Feng WANG, Jiquan LI, Hongpeng QU, Xiaodong PENG","doi":"10.1088/2058-6272/ad0d57","DOIUrl":"https://doi.org/10.1088/2058-6272/ad0d57","url":null,"abstract":"Ion temperature gradient (ITG)-driven turbulence with embedded static magnetic islands is simulated by utilizing a gyrokinetic theory-based global turbulence transport code (GKNET) in this work. Different from the traditional equilibrium circular magnetic-surface average (EMSA) method, an advanced algorithm that calculates the perturbed magnetic-surface average (PMSA) of the electric potential has been developed to precisely deal with the zonal flow component in a non-circular magnetic surface perturbed by magnetic islands. Simulations show that the electric potential vortex structure inside islands induced by the magnetic islands is usually of odd parity when using the EMSA method. It is found that the odd symmetry vortex can transfer into an even one after a steep zonal flow gradient, i.e. the flow shear has been built in the vicinity of the magnetic islands by adopting the PMSA algorithm. The phase of the potential vortex in the poloidal cross section is coupled with the zonal flow shear. Such an electric potential vortex mode may be of essential importance in wide topics, such as the turbulence spreading across magnetic islands, neoclassical tearing mode physics, and also the interaction dynamics between the micro-turbulence and MHD activities.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139093687","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 : 2023-12-28DOI: 10.1088/2058-6272/ad1980
Zi Liu, Tianbo Wang, Muquan Wu, Zheng-ping Luo, Shuo Wang, Tengfei Sun, Bingjia Xiao, Jiangang Li
An accurate plasma current profile has irreplaceable value for the steady state operation of the plasma. In this study, the plasma current tomography based on Bayesian inference is applied to HL-2A device and used to reconstruct the plasma current profile, two different Bayesian probability priors are tried, namely the Conditional AutoRegressive (CAR) prior and the Advanced Squared Exponential (ASE) kernel prior. Compared to the CAR prior, the ASE kernel prior adopts non-stationary hyperparameters and introduces the current profile of the reference discharge into the hyperparameters, which can make the shape of the current profile more flexible in space. The results indicate that the ASE prior couples more information, reduces the probability of unreasonable solutions, and achieves higher reconstruction accuracy.
{"title":"Plasma current tomography for HL-2A based on Bayesian inference","authors":"Zi Liu, Tianbo Wang, Muquan Wu, Zheng-ping Luo, Shuo Wang, Tengfei Sun, Bingjia Xiao, Jiangang Li","doi":"10.1088/2058-6272/ad1980","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1980","url":null,"abstract":"An accurate plasma current profile has irreplaceable value for the steady state operation of the plasma. In this study, the plasma current tomography based on Bayesian inference is applied to HL-2A device and used to reconstruct the plasma current profile, two different Bayesian probability priors are tried, namely the Conditional AutoRegressive (CAR) prior and the Advanced Squared Exponential (ASE) kernel prior. Compared to the CAR prior, the ASE kernel prior adopts non-stationary hyperparameters and introduces the current profile of the reference discharge into the hyperparameters, which can make the shape of the current profile more flexible in space. The results indicate that the ASE prior couples more information, reduces the probability of unreasonable solutions, and achieves higher reconstruction accuracy.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139152520","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 : 2023-12-28DOI: 10.1088/2058-6272/ad197f
Tayyba Sajid, S. Bashir, M. Akram, M. Razzaq, K. Mahmood
Two-dimensional (2-D) diagnosis of laser-induced zirconium (Zr) plasma has been experimentally performed using the Time-Of-Flight (TOF) method by employing Faraday cups (FCs), and electric and magnetic probes. The characteristic parameters of laser-induced Zr plasma have been evaluated as a function of different laser irradiances ranging from 4.5 to 11.7 GW cm−2 at different axial positions of 1cm–4 cm with a fixed radial distance of 2 cm. A well-supporting correlation between plume parameters and laser-plasma-produced spontaneous electric and magnetic (E and B) fields has been established. The measurements of characteristic parameters and spontaneously induced fields are observed to have an increasing trend with increasing laser irradiance. Whereas, with increasing spatial distances in both axial and radial directions, plasma parameters (electron/ion number density, temperature and kinetic energy) do not show either continuously increasing or decreasing trends due to various kinetic and dynamic processes during spatial evolution of plume. However, the E and B fields are observed to be always diffusing away from the target. The radial component of electron number densities remains higher than the axial number density component, whereas, axial ion number density at all laser irradiances and axial distances remains higher than radial ion number density. The higher axial Self-Generated Electric Field (SGEF) values than radial SGEF are correlated with the effective charge-separation mechanism of electrons and ions. The generation of Self-Generated Magnetic Field (SGMF) is observed dominantly in the radial direction at increasing laser irradiance as compared to the axial one due to the deflection of fast-moving electrons and persistence of Two-Electron Temperature (TET) on the radial axis.
通过使用法拉第杯（FC）、电探针和磁探针，利用飞行时间（TOF）方法对激光诱导锆（Zr）等离子体进行了二维（2-D）诊断。在 1 厘米至 4 厘米的不同轴向位置和 2 厘米的固定径向距离上，评估了激光诱导锆等离子体的特征参数与 4.5 至 11.7 GW cm-2 不同激光辐照度的函数关系。羽流参数与激光等离子体产生的自发电场和磁场（E 场和 B 场）之间的相关性得到了很好的证实。据观察，随着激光辐照度的增加，特征参数和自发感应场的测量值呈上升趋势。而随着轴向和径向空间距离的增加，等离子体参数（电子/离子数密度、温度和动能）并没有显示出持续增加或减少的趋势，这是由于羽流空间演变过程中的各种动力学和动态过程造成的。不过，观察到 E 场和 B 场始终在向远离目标的方向扩散。电子数密度的径向分量仍然高于轴向数密度分量，而在所有激光辐照度和轴向距离下，轴向离子数密度仍然高于径向离子数密度。轴向自发电场值高于径向自发电场值与电子和离子的有效电荷分离机制有关。在激光辐照度增加时，与轴向相比，径向主要会产生自发磁场（SGMF），这是由于快速移动电子的偏转和径向轴上双电子温度（TET）的持续存在。
{"title":"Two-dimensional investigation of characteristics parameters and their gradients for the self-generated electric and magnetic fields of laser-induced zirconium plasma","authors":"Tayyba Sajid, S. Bashir, M. Akram, M. Razzaq, K. Mahmood","doi":"10.1088/2058-6272/ad197f","DOIUrl":"https://doi.org/10.1088/2058-6272/ad197f","url":null,"abstract":"Two-dimensional (2-D) diagnosis of laser-induced zirconium (Zr) plasma has been experimentally performed using the Time-Of-Flight (TOF) method by employing Faraday cups (FCs), and electric and magnetic probes. The characteristic parameters of laser-induced Zr plasma have been evaluated as a function of different laser irradiances ranging from 4.5 to 11.7 GW cm−2 at different axial positions of 1cm–4 cm with a fixed radial distance of 2 cm. A well-supporting correlation between plume parameters and laser-plasma-produced spontaneous electric and magnetic (E and B) fields has been established. The measurements of characteristic parameters and spontaneously induced fields are observed to have an increasing trend with increasing laser irradiance. Whereas, with increasing spatial distances in both axial and radial directions, plasma parameters (electron/ion number density, temperature and kinetic energy) do not show either continuously increasing or decreasing trends due to various kinetic and dynamic processes during spatial evolution of plume. However, the E and B fields are observed to be always diffusing away from the target. The radial component of electron number densities remains higher than the axial number density component, whereas, axial ion number density at all laser irradiances and axial distances remains higher than radial ion number density. The higher axial Self-Generated Electric Field (SGEF) values than radial SGEF are correlated with the effective charge-separation mechanism of electrons and ions. The generation of Self-Generated Magnetic Field (SGMF) is observed dominantly in the radial direction at increasing laser irradiance as compared to the axial one due to the deflection of fast-moving electrons and persistence of Two-Electron Temperature (TET) on the radial axis.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139152557","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 : 2023-12-26DOI: 10.1088/2058-6272/ad18d0
Xiangbei Wu, Cheng Yang, Jiawei Luo, Yan Shen
The bipolar ionic liquid thruster employ ionic liquid as propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC) power source, effectively suppressing electrochemical reaction and ensuring charge neutrality. Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation. This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions. The AC power supply was set within the frequency range of 0.5 to 64 Hz, with eight specific frequency conditions selected experimentation. The experimental results indicate that the thruster operate steadily within a voltage range of ±1470 to ±1920 V, with corresponding positive polarity current ranging from 0.41 to 4.91 μA and negative polarity current ranging from -0.49 to -4.10 μA. During voltage polarity switching, an emission delay occurs, manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets. Extended emission test were conducted at 16 Hz demonstrating approximately 1 hour and 50 minutes of consistent emission before intermittent discharge. These findings underscore the favorable impact of alternating current conditions within the 8 to 16 Hz range on the self-neutralization capability of the ionic liquid thruster.
{"title":"Experimental investigation on the polarity switching process with different operating frequencies of the bipolar ionic liquid thruster","authors":"Xiangbei Wu, Cheng Yang, Jiawei Luo, Yan Shen","doi":"10.1088/2058-6272/ad18d0","DOIUrl":"https://doi.org/10.1088/2058-6272/ad18d0","url":null,"abstract":"The bipolar ionic liquid thruster employ ionic liquid as propellant to discharge positively and negatively charged high-energy particles under an alternating current(AC) power source, effectively suppressing electrochemical reaction and ensuring charge neutrality. Determining an optimal AC supply power source frequency is critical for sustained stable thruster operation. This study focuses on the emission characteristics of the ionic liquid thruster under varied AC conditions. The AC power supply was set within the frequency range of 0.5 to 64 Hz, with eight specific frequency conditions selected experimentation. The experimental results indicate that the thruster operate steadily within a voltage range of ±1470 to ±1920 V, with corresponding positive polarity current ranging from 0.41 to 4.91 μA and negative polarity current ranging from -0.49 to -4.10 μA. During voltage polarity switching, an emission delay occurs, manifested as a prominent peak signal caused by circuit capacitance characteristics and a minor peak signal resulting from liquid droplets. Extended emission test were conducted at 16 Hz demonstrating approximately 1 hour and 50 minutes of consistent emission before intermittent discharge. These findings underscore the favorable impact of alternating current conditions within the 8 to 16 Hz range on the self-neutralization capability of the ionic liquid thruster.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139155448","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 : 2023-12-22DOI: 10.1088/2058-6272/ad1875
Yaojun Xiang, Xiao-Kun Wang, Yongxin Liu, Younian Wang
Effect of a negative direct current (DC) bias,|Vdc|, on the electrical parameters and discharge mode is investigated experimentally in a radio frequency (RF) capacitively coupled Ar plasma operated at different RF voltage amplitudes and different gas pressures. The electron density is measured by using a hairpin probe and the spatio-temporal distribution of electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy, and the electrical parameters are obtained based on the waveforms of the electrode voltage and the plasma current measured by a voltage and current probe. It was found that at a low |Vdc|, i.e., in α mode, the electron density and the RF current decline with increasing |Vdc|, and meanwhile, the plasma impedance becomes more capacitive, due to a widened sheath. So, the RF power deposition is suppressed. When |Vdc| exceeds a certain value, the plasma turns into α-γ hybrid mode (or the discharge becomes dominated by the γ-mode), manifesting a drastically-growing electron density and a moderately-increasing RF current. Meanwhile, the plasma impedance becomes more resistive, so the RF power deposition is enhanced with |Vdc|. Besides, we found that the electrical parameters show similar dependence on |Vdc| at different RF voltages, and the α-γ mode transition occurs at a lower |Vdc| at a higher RF voltage. By increasing the pressure, the plasma impedance becomes more resistive, so the RF power deposition and the electron density are enhanced. Especially, the α-γ mode transition tends to occur at a lower |Vdc| with the increase of the pressure.
{"title":"Effect of a negative DC bias on a capacitively coupled Ar plasma operated at different radio frequency voltages and gas pressures","authors":"Yaojun Xiang, Xiao-Kun Wang, Yongxin Liu, Younian Wang","doi":"10.1088/2058-6272/ad1875","DOIUrl":"https://doi.org/10.1088/2058-6272/ad1875","url":null,"abstract":"\u0000 Effect of a negative direct current (DC) bias,|Vdc|, on the electrical parameters and discharge mode is investigated experimentally in a radio frequency (RF) capacitively coupled Ar plasma operated at different RF voltage amplitudes and different gas pressures. The electron density is measured by using a hairpin probe and the spatio-temporal distribution of electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy, and the electrical parameters are obtained based on the waveforms of the electrode voltage and the plasma current measured by a voltage and current probe. It was found that at a low |Vdc|, i.e., in α mode, the electron density and the RF current decline with increasing |Vdc|, and meanwhile, the plasma impedance becomes more capacitive, due to a widened sheath. So, the RF power deposition is suppressed. When |Vdc| exceeds a certain value, the plasma turns into α-γ hybrid mode (or the discharge becomes dominated by the γ-mode), manifesting a drastically-growing electron density and a moderately-increasing RF current. Meanwhile, the plasma impedance becomes more resistive, so the RF power deposition is enhanced with |Vdc|. Besides, we found that the electrical parameters show similar dependence on |Vdc| at different RF voltages, and the α-γ mode transition occurs at a lower |Vdc| at a higher RF voltage. By increasing the pressure, the plasma impedance becomes more resistive, so the RF power deposition and the electron density are enhanced. Especially, the α-γ mode transition tends to occur at a lower |Vdc| with the increase of the pressure.","PeriodicalId":20250,"journal":{"name":"Plasma Science & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138944831","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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