Pub Date : 2025-11-20DOI: 10.1109/TPS.2025.3630051
J. T. Bonnema;S. Lisgo;A. J. M. Pemen;T. Huiskamp
Project Elpis investigates the use of a plasma focus (PF) as a commercial radiation source, ideally for fusion energy generation. A PF is a type of pinch in which a short-lived, hot, and dense plasma is created, in which fusion reactions can take place. Since this is an energy-dense pulsed apparatus, eventually a suitable pulse source must be designed. First, the requirements for the initial research prototype have been determined (10 kV, 10 kJ, 500 kA, and 25 $mu $ s). Due to the requirement for a long operational lifetime, in this work, we will investigate a solid-state pulse switch implementation and develop a first (lower power, 1-kV) prototype for the initial research demonstrator. Different solid-state switches (an insulated gate bipolar transistor (IGBT) and two MOS-gated thyristors) have been experimentally selected for their current conduction capabilities in the required regime, after which a final selection is made. Next, a sinusoidal discharge pulse source is designed to measure the current-sharing performance of four such switches in parallel. The results show a desirable current sharing performance (<15% difference) below 20-kA peak. Simultaneously, a simulation model is developed to aid in further system design. Next, a switch module consisting of 16 switches in parallel has been designed. Again, sufficient current sharing behavior is observed (<5% difference) up to 140-kA peak (single-shot and destructive) and 70-kA peak for repetitive operation. Finally, simulations demonstrating the feasibility of the 500-kA prototype are shown, as well as a successful simulated operation with PF.
{"title":"High-Current, Solid-State Switch for Dense Plasma Focus Applications","authors":"J. T. Bonnema;S. Lisgo;A. J. M. Pemen;T. Huiskamp","doi":"10.1109/TPS.2025.3630051","DOIUrl":"https://doi.org/10.1109/TPS.2025.3630051","url":null,"abstract":"Project Elpis investigates the use of a plasma focus (PF) as a commercial radiation source, ideally for fusion energy generation. A PF is a type of pinch in which a short-lived, hot, and dense plasma is created, in which fusion reactions can take place. Since this is an energy-dense pulsed apparatus, eventually a suitable pulse source must be designed. First, the requirements for the initial research prototype have been determined (10 kV, 10 kJ, 500 kA, and 25 <inline-formula> <tex-math>$mu $ </tex-math></inline-formula>s). Due to the requirement for a long operational lifetime, in this work, we will investigate a solid-state pulse switch implementation and develop a first (lower power, 1-kV) prototype for the initial research demonstrator. Different solid-state switches (an insulated gate bipolar transistor (IGBT) and two MOS-gated thyristors) have been experimentally selected for their current conduction capabilities in the required regime, after which a final selection is made. Next, a sinusoidal discharge pulse source is designed to measure the current-sharing performance of four such switches in parallel. The results show a desirable current sharing performance (<15% difference) below 20-kA peak. Simultaneously, a simulation model is developed to aid in further system design. Next, a switch module consisting of 16 switches in parallel has been designed. Again, sufficient current sharing behavior is observed (<5% difference) up to 140-kA peak (single-shot and destructive) and 70-kA peak for repetitive operation. Finally, simulations demonstrating the feasibility of the 500-kA prototype are shown, as well as a successful simulated operation with PF.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3878-3891"},"PeriodicalIF":1.5,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754238","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}
This article performs a systematic investigation into the waveform characteristics of natural lightning electric fields at 4000-m altitudes. Using measured data from Lhasa and Yangbajing observation stations in Tibet, the study conducts a detailed statistical analysis of time-domain parameters (e.g., rise time, half-peak width, and zero-crossing duration) for positive first return strokes, negative first return strokes, and negative subsequent return strokes. By integrating the physical characteristics of the low-pressure, low-density atmospheric environment, the study investigates the underlying causes of parameter discrepancies. The study reveals that the time-domain parameters of the first return stroke at high altitudes exhibit significant prolongation, including rise time, half-peak width, and zero-crossing duration, which reflects the delayed breakdown of the discharge channel and altered charge neutralization mechanisms under low-pressure conditions. Moreover, the proportion of slow-front energy is markedly reduced, indicating that the rarefied atmosphere exerts stronger dissipation on the low-frequency components of the lightning waveform while better preserving the high-frequency energy concentrated near the peak. For subsequent return strokes, although the preexisting ionization channel reduces the probability of polarity conversion, parameters such as zero-crossing duration remain elevated, underscoring the sustained influence of the low-density atmosphere on electromagnetic field oscillations and charge dissipation processes. This study confirms the systematic influence of altitude on lightning electric field waveforms. These findings provide crucial theoretical foundations and data support for understanding lightning disaster mechanisms, optimizing lightning location technology and early warning systems, and designing lightning protection for transmission lines in high-altitude regions.
{"title":"Study on Waveform Characteristics of Natural Lightning Electric Field at 4000-m Altitude","authors":"Haoxi Cong;Min Tang;Zixin Guo;Yu Li;Getu Zhaori;Qingmin Li;Weidong Shi;Xia Zhao;Zhensheng Wu","doi":"10.1109/TPS.2025.3624816","DOIUrl":"https://doi.org/10.1109/TPS.2025.3624816","url":null,"abstract":"This article performs a systematic investigation into the waveform characteristics of natural lightning electric fields at 4000-m altitudes. Using measured data from Lhasa and Yangbajing observation stations in Tibet, the study conducts a detailed statistical analysis of time-domain parameters (e.g., rise time, half-peak width, and zero-crossing duration) for positive first return strokes, negative first return strokes, and negative subsequent return strokes. By integrating the physical characteristics of the low-pressure, low-density atmospheric environment, the study investigates the underlying causes of parameter discrepancies. The study reveals that the time-domain parameters of the first return stroke at high altitudes exhibit significant prolongation, including rise time, half-peak width, and zero-crossing duration, which reflects the delayed breakdown of the discharge channel and altered charge neutralization mechanisms under low-pressure conditions. Moreover, the proportion of slow-front energy is markedly reduced, indicating that the rarefied atmosphere exerts stronger dissipation on the low-frequency components of the lightning waveform while better preserving the high-frequency energy concentrated near the peak. For subsequent return strokes, although the preexisting ionization channel reduces the probability of polarity conversion, parameters such as zero-crossing duration remain elevated, underscoring the sustained influence of the low-density atmosphere on electromagnetic field oscillations and charge dissipation processes. This study confirms the systematic influence of altitude on lightning electric field waveforms. These findings provide crucial theoretical foundations and data support for understanding lightning disaster mechanisms, optimizing lightning location technology and early warning systems, and designing lightning protection for transmission lines in high-altitude regions.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3943-3955"},"PeriodicalIF":1.5,"publicationDate":"2025-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754241","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}
Pub Date : 2025-11-11DOI: 10.1109/TPS.2025.3625419
Mohd Farman Ali;Abhishek Kumar;Gaurav Varshney
A combination of vanadium dioxide (VO2) resonators assisted by a graphene sheet operating with multiple resonances can provide a way to electrically separate and merge the resonance spectrum. The device operation can be set to multifunctionality through electrical variation by generating multiple narrow and broad absorption peaks together. VO2 allows to provide the thermally switchable absorption response. The adequate Fermi energy of graphene can excite the resonances with an electrically controlled phase. Hence, tunable out-of-phase resonances can be achieved along with the in-phase resonances. The spectrum of out-of-phase resonances remains separated with a narrow line shape. In addition, in-phase resonances provide a wideband due to their merged spectrum. A thin dielectric loading above the absorber can further excite a greater number of the out-of-phase resonances to generate the multiple narrow absorption peaks along with the broad absorption band. An ultrathin geometry of thickness around $approx lambda $ /215 is achieved; $lambda $ is the free space wavelength. The proposed absorber can be used in sensing and shielding applications at terahertz (THz) frequency.
{"title":"Multicontrolled In/Out-of-Phase Resonances in Graphene-Assisted VO2-Based Multiband Metal-Free THz Absorber","authors":"Mohd Farman Ali;Abhishek Kumar;Gaurav Varshney","doi":"10.1109/TPS.2025.3625419","DOIUrl":"https://doi.org/10.1109/TPS.2025.3625419","url":null,"abstract":"A combination of vanadium dioxide (VO<sub>2</sub>) resonators assisted by a graphene sheet operating with multiple resonances can provide a way to electrically separate and merge the resonance spectrum. The device operation can be set to multifunctionality through electrical variation by generating multiple narrow and broad absorption peaks together. VO<sub>2</sub> allows to provide the thermally switchable absorption response. The adequate Fermi energy of graphene can excite the resonances with an electrically controlled phase. Hence, tunable out-of-phase resonances can be achieved along with the in-phase resonances. The spectrum of out-of-phase resonances remains separated with a narrow line shape. In addition, in-phase resonances provide a wideband due to their merged spectrum. A thin dielectric loading above the absorber can further excite a greater number of the out-of-phase resonances to generate the multiple narrow absorption peaks along with the broad absorption band. An ultrathin geometry of thickness around <inline-formula> <tex-math>$approx lambda $ </tex-math></inline-formula>/215 is achieved; <inline-formula> <tex-math>$lambda $ </tex-math></inline-formula> is the free space wavelength. The proposed absorber can be used in sensing and shielding applications at terahertz (THz) frequency.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3974-3979"},"PeriodicalIF":1.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754244","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}
Pub Date : 2025-11-11DOI: 10.1109/TPS.2025.3621726
Simon Kimpeler;Frederik Mingers;Verena West;Tim Ballweber;Andres Tönnesmann;Daniel Fuhrmann;Willem Leterme
A tube geometry in air is used to experimentally investigate polyamide 6.6 (PA6.6) ablation mass and rates depending on the dissipated arc energy for direct current (dc) arcs while varying the tube length, inner channel radius, and arc current. The geometry is designed to minimize the influences of external factors such as contact vapor. Furthermore, a magnetohydrodynamic (MHD) arc model with a four-band selection for radiation modeling designed for air-PA66 is developed. The experimental results indicate a linear relationship between the ablation rate and dissipated arc energy. Moreover, increasing ablation rates and arc voltages are observed for a decreasing tube channel radius. The arc model is found to be able to predict these trends.
{"title":"Influence of Polyamide 6.6 Ablation on Direct Current Arcs—Experiment and Simulation","authors":"Simon Kimpeler;Frederik Mingers;Verena West;Tim Ballweber;Andres Tönnesmann;Daniel Fuhrmann;Willem Leterme","doi":"10.1109/TPS.2025.3621726","DOIUrl":"https://doi.org/10.1109/TPS.2025.3621726","url":null,"abstract":"A tube geometry in air is used to experimentally investigate polyamide 6.6 (PA6.6) ablation mass and rates depending on the dissipated arc energy for direct current (dc) arcs while varying the tube length, inner channel radius, and arc current. The geometry is designed to minimize the influences of external factors such as contact vapor. Furthermore, a magnetohydrodynamic (MHD) arc model with a four-band selection for radiation modeling designed for air-PA66 is developed. The experimental results indicate a linear relationship between the ablation rate and dissipated arc energy. Moreover, increasing ablation rates and arc voltages are observed for a decreasing tube channel radius. The arc model is found to be able to predict these trends.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3901-3909"},"PeriodicalIF":1.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754236","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}
Pub Date : 2025-11-11DOI: 10.1109/TPS.2025.3627528
Leila Karami Gadallo
Melanoma is considered one of the dangerous kinds of skin cancer. In vitro and in vivo studies show that cold atmospheric plasma (CAP) demonstrates promising therapeutic potential for melanoma treatment. This study presents three major advances in CAP therapy: 1) development of the first machine learning (ML) framework for treatment prediction and optimization; 2) introduction of the plasma dose concept through quantitative parameter compensation; and 3) establishment of parameter substitution laws enabling treatment efficiency enhancement. We developed and evaluated five ML models—random forest (RF), decision tree, support vector machine (SVM), gradient boosting (XGB), and K-nearest neighbors (KNNs)—for predicting melanoma cell responses to CAP treatment. XGB achieved the highest performance [84% accuracy (ACC)], effectively capturing nonlinear correlations between plasma parameters and cellular viability. Novel parameter substitution analysis revealed that 50% reduction in treatment distance compensates for 40% reduction in treatment time while maintaining maximum cytotoxicity. These quantitative relationships enable the definition of plasma dose through multiparameter compensation, providing standardized protocols for clinical translation.
{"title":"Prediction of Cytotoxicity Effects of Cold Atmospheric Plasma on Melanoma Using Machine Learning Models","authors":"Leila Karami Gadallo","doi":"10.1109/TPS.2025.3627528","DOIUrl":"https://doi.org/10.1109/TPS.2025.3627528","url":null,"abstract":"Melanoma is considered one of the dangerous kinds of skin cancer. In vitro and in vivo studies show that cold atmospheric plasma (CAP) demonstrates promising therapeutic potential for melanoma treatment. This study presents three major advances in CAP therapy: 1) development of the first machine learning (ML) framework for treatment prediction and optimization; 2) introduction of the plasma dose concept through quantitative parameter compensation; and 3) establishment of parameter substitution laws enabling treatment efficiency enhancement. We developed and evaluated five ML models—random forest (RF), decision tree, support vector machine (SVM), gradient boosting (XGB), and K-nearest neighbors (KNNs)—for predicting melanoma cell responses to CAP treatment. XGB achieved the highest performance [84% accuracy (ACC)], effectively capturing nonlinear correlations between plasma parameters and cellular viability. Novel parameter substitution analysis revealed that 50% reduction in treatment distance compensates for 40% reduction in treatment time while maintaining maximum cytotoxicity. These quantitative relationships enable the definition of plasma dose through multiparameter compensation, providing standardized protocols for clinical translation.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"4009-4015"},"PeriodicalIF":1.5,"publicationDate":"2025-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754240","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}
Pub Date : 2025-11-07DOI: 10.1109/TPS.2025.3627273
Tong He;Hui Ran Zeng;Kai Li
In this article, we present a theoretical framework for calculation and analysis of the receiving properties of an electrically thin loop antenna immersed in an anisotropic magnetoplasma. The considered receiving loop antenna is assumed to be at arbitrary orientations relative to the background magnetic field and is illuminated by an arbitrarily directed incident very-low-frequency (VLF: 3–30 kHz) wave. Based on a complete Fourier series analysis, a closed-form expression for the current distribution along the loop antenna with a load connected to its terminals is rigorously derived by taking into account the influences of both the even and odd components of the incident field as well as the effects of the extraordinary wave and ordinary wave that coexist in the anisotropic plasma. Computations and analyses show that variations on the dip angle (from 15° to 75°) or azimuthal angle (from 30° to 180°) between the loop antenna and the static magnetic field would to some extent change the distribution form of the induced current, while the voltage generated at the antenna terminals is reduced by ~0.11 V when the incidence angle of the incident VLF wave varies from 0° to 89°. In addition, loop antennas with a larger electrical size exhibit better receiving performances such that the open-circuit voltage may be enhanced from less than 0.1 V to nearly 2.1 V as the loop electric size increases from 0.25 to 2.5.
{"title":"Current Distribution in Arbitrarily Oriented Receiving Loop Antenna in an Anisotropic Plasma","authors":"Tong He;Hui Ran Zeng;Kai Li","doi":"10.1109/TPS.2025.3627273","DOIUrl":"https://doi.org/10.1109/TPS.2025.3627273","url":null,"abstract":"In this article, we present a theoretical framework for calculation and analysis of the receiving properties of an electrically thin loop antenna immersed in an anisotropic magnetoplasma. The considered receiving loop antenna is assumed to be at arbitrary orientations relative to the background magnetic field and is illuminated by an arbitrarily directed incident very-low-frequency (VLF: 3–30 kHz) wave. Based on a complete Fourier series analysis, a closed-form expression for the current distribution along the loop antenna with a load connected to its terminals is rigorously derived by taking into account the influences of both the even and odd components of the incident field as well as the effects of the extraordinary wave and ordinary wave that coexist in the anisotropic plasma. Computations and analyses show that variations on the dip angle (from 15° to 75°) or azimuthal angle (from 30° to 180°) between the loop antenna and the static magnetic field would to some extent change the distribution form of the induced current, while the voltage generated at the antenna terminals is reduced by ~0.11 V when the incidence angle of the incident VLF wave varies from 0° to 89°. In addition, loop antennas with a larger electrical size exhibit better receiving performances such that the open-circuit voltage may be enhanced from less than 0.1 V to nearly 2.1 V as the loop electric size increases from 0.25 to 2.5.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3929-3942"},"PeriodicalIF":1.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754246","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}
Pub Date : 2025-11-07DOI: 10.1109/TPS.2025.3625935
Tong He;Hui Ran Zeng;Kai Li
For very-low-frequency (VLF: 3–30 kHz) spaceborne transmissions, insulated antennas covered with a thin dielectric layer are less sensitive to the characteristics of the ambient ionospheric plasma, and therefore, more desirable than bare antennas. In this article, the problem of an insulated linear antenna operating in the receiving mode and immersed in an anisotropic magnetoplasma is treated analytically. The considered antenna is located in the F2 layer of the ionosphere, where the ambient plasma is assumed to be a highly ionized plasma, and the effect of neutral particle collision on wave propagation is neglected. The closed-form expressions for the axial electric fields along the surface of the antenna are rigorously derived through analyzing a transmedium boundary condition (magnetoplasma–dielectric antenna), and the integral equation satisfied for the antenna current distribution is established and solved to determine the induced current and terminal voltage due to the incident VLF wave. Computations and analyses show that the addition of the insulation would make the antenna less affected by the property changes of the ambient magnetoplasma, and a thicker insulating layer may lead to a decrease in the magnitudes of both the induced current distribution and the voltage developed across the antenna terminals. The research might provide a theoretical basis for the practical use of insulated receiving linear antennas in realistic VLF spaceborne application scenarios.
{"title":"Analysis of an Insulated Receiving Linear Antenna in an Anisotropic Magnetoplasma","authors":"Tong He;Hui Ran Zeng;Kai Li","doi":"10.1109/TPS.2025.3625935","DOIUrl":"https://doi.org/10.1109/TPS.2025.3625935","url":null,"abstract":"For very-low-frequency (VLF: 3–30 kHz) spaceborne transmissions, insulated antennas covered with a thin dielectric layer are less sensitive to the characteristics of the ambient ionospheric plasma, and therefore, more desirable than bare antennas. In this article, the problem of an insulated linear antenna operating in the receiving mode and immersed in an anisotropic magnetoplasma is treated analytically. The considered antenna is located in the F<sub>2</sub> layer of the ionosphere, where the ambient plasma is assumed to be a highly ionized plasma, and the effect of neutral particle collision on wave propagation is neglected. The closed-form expressions for the axial electric fields along the surface of the antenna are rigorously derived through analyzing a transmedium boundary condition (magnetoplasma–dielectric antenna), and the integral equation satisfied for the antenna current distribution is established and solved to determine the induced current and terminal voltage due to the incident VLF wave. Computations and analyses show that the addition of the insulation would make the antenna less affected by the property changes of the ambient magnetoplasma, and a thicker insulating layer may lead to a decrease in the magnitudes of both the induced current distribution and the voltage developed across the antenna terminals. The research might provide a theoretical basis for the practical use of insulated receiving linear antennas in realistic VLF spaceborne application scenarios.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3918-3928"},"PeriodicalIF":1.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754233","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}
Ultrafast laser pulse and its second-harmonic, that is, the two-color laser fields, can generate a plasma filament that emits terahertz (THz) waves. By specially designing the structure of plasma filaments, THz emissions can be controlled in their spectrum and amplitude. In this study, we formed an array of stable filaments along the laser propagation to control the far-field THz generation. Phase modulation of the laser wavefront was achieved using a fan-shaped segmentation arrangement based on a spatial light modulator (SLM), where the entire phase modulation surface of the SLM was divided into $M$ sectors, each further split into $N$ subsectors. Simulations indicate that even $M$ values improve filament symmetry by canceling transverse field components at the focus, while increasing $M$ enhances spatial separation between filaments. Experimentally, optimal values were determined to be $M =4$ , under which the THz peak-to-peak amplitude increased by approximately five times compared to $M =2$ and 4 times compared to $M =10$ . Furthermore, the redshifts of the output THz spectrum can be found when increasing $M$ , and notable interference patterns are presented under all $M$ values. These results show that both the spectrum and amplitude of THz waves from plasma filaments can be adjusted by controlling the ionizing laser fields. Our findings demonstrate a promising approach for modulating THz waves through programmable and reconfigurable plasma filaments designed via the SLM.
{"title":"In Situ Optimization Terahertz Generation From Axial Plasma Filament Arrays by Fan-Shaped Phase Segmentation","authors":"Aijun Xuan;Mingxin Gao;Yangmei Li;Yifei Feng;Lu Liu;Jicai Liu;Yindong Huang","doi":"10.1109/TPS.2025.3625176","DOIUrl":"https://doi.org/10.1109/TPS.2025.3625176","url":null,"abstract":"Ultrafast laser pulse and its second-harmonic, that is, the two-color laser fields, can generate a plasma filament that emits terahertz (THz) waves. By specially designing the structure of plasma filaments, THz emissions can be controlled in their spectrum and amplitude. In this study, we formed an array of stable filaments along the laser propagation to control the far-field THz generation. Phase modulation of the laser wavefront was achieved using a fan-shaped segmentation arrangement based on a spatial light modulator (SLM), where the entire phase modulation surface of the SLM was divided into <inline-formula> <tex-math>$M$ </tex-math></inline-formula> sectors, each further split into <inline-formula> <tex-math>$N$ </tex-math></inline-formula> subsectors. Simulations indicate that even <inline-formula> <tex-math>$M$ </tex-math></inline-formula> values improve filament symmetry by canceling transverse field components at the focus, while increasing <inline-formula> <tex-math>$M$ </tex-math></inline-formula> enhances spatial separation between filaments. Experimentally, optimal values were determined to be <inline-formula> <tex-math>$M =4$ </tex-math></inline-formula>, under which the THz peak-to-peak amplitude increased by approximately five times compared to <inline-formula> <tex-math>$M =2$ </tex-math></inline-formula> and 4 times compared to <inline-formula> <tex-math>$M =10$ </tex-math></inline-formula>. Furthermore, the redshifts of the output THz spectrum can be found when increasing <inline-formula> <tex-math>$M$ </tex-math></inline-formula>, and notable interference patterns are presented under all <inline-formula> <tex-math>$M$ </tex-math></inline-formula> values. These results show that both the spectrum and amplitude of THz waves from plasma filaments can be adjusted by controlling the ionizing laser fields. Our findings demonstrate a promising approach for modulating THz waves through programmable and reconfigurable plasma filaments designed via the SLM.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3992-3999"},"PeriodicalIF":1.5,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754243","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}
Pub Date : 2025-11-03DOI: 10.1109/TPS.2025.3621649
Zhenfeng Liu;Hongwu Li;Yongdong Li;Zhenjie Ding
This article addresses the issues of oscillation pulses and extended recovery time caused by inadequate matching between switching devices and drive circuits in a nanosecond pulse generator based on the diode opening switch (DOS). To this end, the single-switch drive circuit is simplified and analyzed, and the underlying mechanisms leading to oscillation pulses are investigated in detail. An optimization matching method for the circuit is proposed, through which a set of circuit parameters is derived according to the driving conditions. Based on these parameters, a practical experimental platform for the nanosecond pulse generator is constructed. Experimental results demonstrate that the output waveform of the designed DOS-based generator exhibits no significant oscillation pulses. At a pulse repetition rate of 3.4 MHz, the generator delivers an output pulse with a peak voltage of 1.05 kV, thereby verifying the effectiveness of the proposed optimization method and enabling operation at a higher repetition rate.
{"title":"Optimization of Nanosecond Pulse Source Based on Single-Switch Drive Circuit","authors":"Zhenfeng Liu;Hongwu Li;Yongdong Li;Zhenjie Ding","doi":"10.1109/TPS.2025.3621649","DOIUrl":"https://doi.org/10.1109/TPS.2025.3621649","url":null,"abstract":"This article addresses the issues of oscillation pulses and extended recovery time caused by inadequate matching between switching devices and drive circuits in a nanosecond pulse generator based on the diode opening switch (DOS). To this end, the single-switch drive circuit is simplified and analyzed, and the underlying mechanisms leading to oscillation pulses are investigated in detail. An optimization matching method for the circuit is proposed, through which a set of circuit parameters is derived according to the driving conditions. Based on these parameters, a practical experimental platform for the nanosecond pulse generator is constructed. Experimental results demonstrate that the output waveform of the designed DOS-based generator exhibits no significant oscillation pulses. At a pulse repetition rate of 3.4 MHz, the generator delivers an output pulse with a peak voltage of 1.05 kV, thereby verifying the effectiveness of the proposed optimization method and enabling operation at a higher repetition rate.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 12","pages":"3874-3877"},"PeriodicalIF":1.5,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145754230","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}
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