IEEE Transactions on Plasma Science最新文献

{"title":"Experimental Study on Spatiotemporal Evolution and Triggering Mechanism of Initial Plasma in Laser-Triggered Vacuum Switch","authors":"Wenjun Xiang;Xubin Li;Minfu Liao;Gang Lu;Liang Bu;Jiexin Hu","doi":"10.1109/TPS.2026.3699564","DOIUrl":"https://doi.org/10.1109/TPS.2026.3699564","url":null,"abstract":"To further clarify the triggering mechanism of a laser-triggered vacuum switch (LTVS), this study systematically investigates the effects of laser energy (10–30 mJ) and applied voltage on the spatiotemporal evolution and triggering process of the initial plasma at a fixed electrode gap of 10 mm, adopting an intensified charge-coupled device (ICCD) high-speed imaging and plasma current diagnostics as the core diagnostic methods. Under zero-voltage conditions, the laser-ablated initial plasma evolves through four successive stages: generation, expansion, diffusion, and decay, with an axial propagation velocity of approximately 14.3 km/s at a laser energy of 10 mJ, and the diffusion morphology of the plasma plume varies significantly under different laser energies. The plasma current and total transported charge increase with laser energy but exhibit a saturation trend at high energy levels. When an external voltage is applied, the induced electric field significantly accelerates the charged particles, induces morphological bifurcation of the plasma plume, and ultimately facilitates the formation of a stable conductive channel bridging the electrode gap, leading to full conduction of the gap at approximately 640 ns.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"4910-4918"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Study of T Mn,1,0 Mode Instabilities in the Annular Cavities of an S-Band High-Power Multibeam Klystron","authors":"Shengchang Wang;Shuji Matsumoto;Takuya Natsui;Toshihiro Matsumoto;Takako Miura;Shigeki Fukuda;Tetsuo Shidara","doi":"10.1109/TPS.2026.3728065","DOIUrl":"https://doi.org/10.1109/TPS.2026.3728065","url":null,"abstract":"This article investigates beam instabilities induced by <inline-formula> <tex-math>${TM}_{n,1,0}$ </tex-math></inline-formula> modes under asymmetric beam conditions in the annular cavity of an S-band multibeam klystron. In S-band or higher-frequency multibeam klystrons (MBKs), annular cavities exhibit a high density of higher-order modes (HOMs), particularly in high-power designs. The <inline-formula> <tex-math>${TM}_{n,{1},{0}}$ </tex-math></inline-formula> modes can potentially trigger beam breakup (BBU) instabilities within the penultimate cavity. We present an analytical study of the power transfer from the beam to the <inline-formula> <tex-math>${TM}_{{n},{1},{0}}$ </tex-math></inline-formula> mode, to clarify that azimuthal asymmetry in the beam currents is the premise to excite the unwanted <inline-formula> <tex-math>${TM}_{{n},{1},{0}}$ </tex-math></inline-formula> mode. Particle-in-cell (PIC) simulations of an S-band 8-beamlet MBK under a single-beam-loss scenario confirm the presence of instability in the penultimate cavity, driven by the <inline-formula> <tex-math>${TM}_{{7},{1},{0}}$ </tex-math></inline-formula> mode at the second harmonic frequency. A solution is proposed to mitigate this issue by introducing 14 evenly spaced fins on the outer boundary and 14 corresponding grooves on the inner boundary, which split the degenerate <inline-formula> <tex-math>${TM}_{{7},{1},{0}}$ </tex-math></inline-formula> mode into two. Additionally, we discuss mode competition between the <inline-formula> <tex-math>${TM}_{{0},{1},{0}}$ </tex-math></inline-formula> and <inline-formula> <tex-math>${TM}_{{1},{1},{0}}$ </tex-math></inline-formula> modes in a C-band annular cavity used for second-harmonic bunching, and this problem can be effectively solved by improving the azimuthal uniformity of the longitudinal electric field in the input cavity.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5069-5076"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Methane Dimerization Under Nonthermal Plasma Conditions: How Does Electrode Material Affect the Process?","authors":"Julia Moszczyńska;Marek Wiśniewski","doi":"10.1109/TPS.2026.3721132","DOIUrl":"https://doi.org/10.1109/TPS.2026.3721132","url":null,"abstract":"The electrode material used to generate nonthermal plasma (NTP) may influence both discharge characteristics and plasma-induced reaction pathways. Here, we investigate the effect of Cu, graphite, and Ni-modified graphite electrodes on nonoxidative methane conversion under variable pressure and applied voltage conditions. The gas-phase composition was monitored online using Fourier-transform infrared spectroscopy, while solid carbonaceous products were characterized by scanning electron microscopy and atomic force microscopy. Methane conversion and <inline-formula> <tex-math>$mathrm{C}_{mathbf {2}}$ </tex-math></inline-formula> product distribution depended strongly on both the electrode material and the operating conditions. Among the investigated systems, pure graphite electrodes provided the highest methane conversion, reaching approximately 80% under selected conditions. Under relatively mild conditions, ethane was the dominant gaseous product. Increasing the applied voltage or pressure shifted the product distribution toward ethene and, subsequently, ethyne. This evolution is consistent with an apparent consecutive reaction network involving methyl-radical recombination followed by progressive dehydrogenation: <inline-formula> <tex-math>$mathrm{CH}_{mathbf {4}}rightarrow $ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{C}_{mathbf {2}}$ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{H}_{mathbf {6}}rightarrow $ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{C}_{mathbf {2}}$ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{H}_{mathbf {4}}rightarrow $ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{C}_{mathbf {2}}$ </tex-math></inline-formula><inline-formula> <tex-math>$mathbf{H}_{mathbf {2}}$ </tex-math></inline-formula>. The electrode is therefore not merely a passive component used to sustain the discharge; its material provides an additional parameter for controlling methane conversion and product selectivity. The observed effects may arise from the combined influence of electrode-dependent plasma characteristics and interactions of plasma-generated species with the electrode surface.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5576-5582"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Nonextensive Effect on Breather Structures in Unmagnetized Dusty Plasma With Two Different Temperature Ions","authors":"Uday Narayan Ghosh;Uttam Kumar Mahato","doi":"10.1109/TPS.2026.3724297","DOIUrl":"https://doi.org/10.1109/TPS.2026.3724297","url":null,"abstract":"The breather soliton dynamics of dust-acoustic waves (DAWs) are examined in an unmagnetized, nonuniform dusty plasma containing negatively charged dust, two-temperature Maxwellian ions, and q-nonextensive electrons. Employing a hydrodynamic fluid model, the Gardner equation (GE), featuring quadratic and cubic nonlinearities, is derived using the reductive perturbation technique (RPT). The exact breather and multisoliton solutions, obtained via the Hirota bilinear method (HBM), exhibit localized oscillatory envelopes that cyclically concentrate and disperse energy without dissipation. Breather properties—amplitude modulation, localization, and oscillation period—are significantly controlled by the q-nonextensive parameter and ion temperature ratios. Higher q values yield narrower, more localized envelopes, while ion temperature asymmetries alter their spatiotemporal morphology. These results establish breather solitons as efficient, nondissipative energy carriers, offering insights into rogue-wave formation, particle acceleration, and energy transport in dusty plasmas, including cometary tails, planetary magnetotails, and interstellar media. Furthermore, as diagnostic tools for nonequilibrium particle populations in space and laboratory conditions.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5273-5280"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Simulations of Vacuum Discharge Dynamics at the High-Voltage Padova Test Facility","authors":"F. Caruggi;A. Celora;G. Croci;A. de Lorenzi;G. Grosso;F. Guiotto;L. Lotto;T. Patton;N. Pilan;O. Putignano;M. Tardocchi;A. Muraro","doi":"10.1109/TPS.2026.3721139","DOIUrl":"https://doi.org/10.1109/TPS.2026.3721139","url":null,"abstract":"In the context of the development activities for the neutral beam injector (NBI) of the ITER tokamak (originally the International Thermonuclear Experimental Reactor), the high voltage Padova test facility (HVPTF) is operational in Padua, Italy, as support for the megavolt ITER injector and concept advancement (MITICA) experiment. The studies at HVPTF are focused on the investigation of electric discharges in vacuum that take place between electrodes at high-voltage differences. The final aim of the activities is the development of strategies for the prevention of breakdown occurrences and the mitigation of their effects. The facility hosts a cylindrical vacuum vessel in which two electrodes can be mounted at variable gap length. Two separate power supplies are employed to apply voltage differences up to 800 kVDC between anode and cathode. During experimental operation, the current and voltage values of the power supplies, as well as the pressure at the walls of the chamber, are sampled by an analog system. In addition, multiple lines of sight are available around the vessel to install other diagnostic systems, such as cameras and radiation detectors, to monitor the emissions coming from the chamber. Past works have presented the analyses performed on the data collected about the emissivity during the discharges, and particular focus was put in recent years on the study of the X-rays emitted by the electrons traveling in vacuum during the discharges, through the Bremsstrahlung effect. In parallel to the experimental activities and results, the development of a simulation environment to replicate the data and justify the hypotheses has been proposed. This tool is based on splitting the complex problem into easier parts and solving them, making use of multiple software tools. This article presents the basis for the development of the simulation model and the preliminary results, both from the simulations of the single phenomena and the integrated analysis of the complete system.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"4891-4900"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11664214","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149175996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TPS Reviewers List 2025","authors":"","doi":"10.1109/TPS.2026.3738289","DOIUrl":"https://doi.org/10.1109/TPS.2026.3738289","url":null,"abstract":"","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5606-5611"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11735327","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149175999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation of Vacuum Microgap Breakdown Characteristics With Two Emission Sources Based on Particle-In-Cell/Monte Carlo Method","authors":"Runze Hu;Lijun Wang;Zhuo Chen;Xiangyu Wang;Hongjian Wang;Cong Wang","doi":"10.1109/TPS.2026.3689334","DOIUrl":"https://doi.org/10.1109/TPS.2026.3689334","url":null,"abstract":"Studying the vacuum breakdown process in a microgap is very useful to understand the breakdown mechanism and improve the performance of vacuum microdevices. In this article, a 2-D vacuum microgap breakdown model with two emission sources was established based on the particle-in-cell/Monte Carlo collision (PIC/MCC) method to simulate the formation process of cathode plasma during the vacuum microgap breakdown. First, the field emission electrons from the two emission sources were set as two different particle types, and it was found that they influenced each other, accelerating the formation of plasma and subsequently speeding up the discharge process. Second, the field enhancement coefficient of one emission source was varied to investigate its impact. Finally, the distance between the two emission sources was also changed to study the influence of different center-to-center distances on the interactions between the emission sources.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"4719-4730"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Interpretive Modeling of Plasma Evolution During Fueling Experiments at CMFX","authors":"S. Mackie;J. G. van de Lindt;J. L. Ball;A. Perevalov;W. Morrissey;Z. Short;B. L. Beaudoin;C. A. Romero-Talamás;J. Rice;R. A. Tinguely","doi":"10.1109/TPS.2026.3707703","DOIUrl":"https://doi.org/10.1109/TPS.2026.3707703","url":null,"abstract":"The centrifugal mirror fusion experiment (CMFX) is an axisymmetric magnetic mirror with a central cathode, which generates an azimuthal, radially sheared, supersonic <inline-formula> <tex-math>$E times B$ </tex-math></inline-formula> flow. The induced rotation stabilizes, confines, and heats the plasma. The diagnostics set on CMFX are sparse, giving limited insight into the state of the plasma. In this work, we developed a time-dependent interpretive analysis framework that uses the applied voltage, input power, and the measured neutron yield rate to infer evolving plasma conditions throughout a discharge. The 0-D MCTrans++ code serves as the core physics model, incorporating centrifugal effects, viscous heating, and angular momentum confinement to infer plasma parameters from operating conditions and experimental observables. An iterative Newton’s method was implemented to solve for the plasma state evolution consistent with experimental measurements averaged over successive time intervals. The interpretive analysis was applied to experiments comparing different fueling strategies, revealing a path to improved performance via several short puffs of fuel spread across the discharge. This insight led to operations at voltages up to 70 kV. Deuterium neutron yields up to <inline-formula> <tex-math>$1.5 times 10^{7}$ </tex-math></inline-formula> n/s were measured, and the ion temperature was inferred to reach 950 eV. Until CMFX gains a more complete diagnostics set, this interpretive analysis framework provides useful insight into the evolution of centrifugal mirror plasmas.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5523-5528"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Status of the 3 MW ECRH System at 105 GHz for WEST","authors":"Lena Delpech;Stefano Alberti;Konstantinos Avramidis;Aline Ayreault;Julien Barra;Jean-Michel Bernard;Vincent Bruno;Francis Bouquey;Ioannis Chelis;Frederic Clairet;Elodie Corbel;Louis Doceul;Frederic Durand;Remi Dumont;Benjamin Ell;Theo Fonghetti;Gerd Gantenbein;Pascal Garibaldi;Sylvain Girard;Timothy Goodman;Jean-Philippe Hogge;Stefan Illy;John Jelonnek;Jianbo Jin;Heinrich Laqua;Francois Legrand;Carsten Lechte;Christophe Lievin;Remi Loux;Patrick Maget;Xavier Regal-Mezin;David Mouyon;Laurent Nicolas;Adam Ouerfelli;Tomasz Rzesnicki;Benjamin Santraine;Sebastian Stanculovic;Pierrick Thrierr;Manfred Thumm;Edouard Velly;WEST Team","doi":"10.1109/TPS.2026.3713597","DOIUrl":"https://doi.org/10.1109/TPS.2026.3713597","url":null,"abstract":"W environment in steady-state tokamak (WEST) experiments aim to achieve long plasma pulses (1000 s) and to expose ITER-like tungsten divertor to power fluxes up to 10 MW/m². To increase the margin to reach H-Mode regimes and control W-impurities in the plasma, the WEST ECRH system is upgraded to a power capability of 3 MW/1000 s at the frequency of 105 GHz. The Tore Supra ECRH antenna has first been improved and is now installed in the equatorial plane of WEST to start ECRH operation on plasma. On the power generation side, a new gyrotron (1 MW/1000 s) designed jointly by KIT and NKUA and manufactured by THALES has been tested in the FULGOR test bench at KIT. The validation of the gyrotron electron optic and Radio Frequency (RF) design with performances of 1 MW/5 s triggered the assembly of the second and third series gyrotrons. In parallel to the gyrotron validation and the installation of the upgraded antenna in the tokamak, the ECRH transmitter has undergone profound changes to adapt the auxiliaries to the new components (gyrotron, superconducting magnet, RF load) such as the cooling system, the high voltage power supply (HVPS) system and the plant environment itself. To control, monitor and ensure the safety of staff and components, the control system, software and communication protocols with the auxiliaries of the gyrotron have been completely refurbished. The commissioning of the complete system now equipped with the first gyrotron started in September 2024 in WEST with the goal of achieving the first ECRH shots during plasma experiments in April 2025. This article reports the main results obtained with the first gyrotron, focuses on the upgrades of the ECRH plant and its commissioning and finally gives a summary of the first experiments with ECRH in WEST.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"5466-5473"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Design and Verification of Self-Voltage Sharing Vacuum Interrupter for High-Voltage GIS","authors":"Guowei Ge;Yuanxin Yao;Xian Cheng;Shuai Du;Hui Chen","doi":"10.1109/TPS.2026.3705219","DOIUrl":"https://doi.org/10.1109/TPS.2026.3705219","url":null,"abstract":"Achieving compact design with high insulation performance is a critical challenge for vacuum interrupters (VIs) in eco-friendly gas-insulated switchgear (GIS). This article addresses the severe nonuniform of potential distribution across the multiple floating shields (MFSs) in VIs for GIS by proposing a novel self-voltage sharing capacitor pattern (SSCP), which integrates grading rings and ring capacitors on the exterior of the VI. The simulation results show that, compared with the conventional VI, the SSCP improves the potential distribution on the MFS by 21.64%, 13.07%, and 6.05%. Furthermore, it achieves a 24.60% reduction in the maximum internal electric field strength and a 35.21% reduction in the external field. To validate these findings, an experimental platform was established for a 145-kV VI. The experimental results regarding the influence of grading capacitance on potential distribution are consistent with the simulation trends. Specifically, with a grading capacitance of 2000 pF, the MFS potential distribution reaches 74.95%<inline-formula> <tex-math>$U$ </tex-math></inline-formula>, 48.87%<inline-formula> <tex-math>$U$ </tex-math></inline-formula>, and 22.63%<inline-formula> <tex-math>$U$ </tex-math></inline-formula>, closely approximating the ideal linear distribution. This research provides a theoretical basis and an optimized structural design for enhancing the insulation performance of high-voltage VIs in GIS.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"54 10","pages":"4791-4798"},"PeriodicalIF":1.6,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}