Pub Date : 2025-09-05DOI: 10.1109/TPS.2025.3603453
Carl Ekdahl
Scorpius is a multipulse linear induction accelerator (LIA) under development for flash radiography. The injector uses 42 solenoids to transport the beam through more than 7 m before it enters the main accelerator. Therefore, the beam might be susceptible to corkscrew motion, which is exacerbated by beam energy spread and focusing magnet misalignments. For energy spread and alignment tolerances expected for Scorpius, a magnetic tune designed to transport a matched beam is shown to produce minimal corkscrew motion.
{"title":"Electron-Beam Corkscrew Motion Through the Scorpius Injector","authors":"Carl Ekdahl","doi":"10.1109/TPS.2025.3603453","DOIUrl":"https://doi.org/10.1109/TPS.2025.3603453","url":null,"abstract":"Scorpius is a multipulse linear induction accelerator (LIA) under development for flash radiography. The injector uses 42 solenoids to transport the beam through more than 7 m before it enters the main accelerator. Therefore, the beam might be susceptible to corkscrew motion, which is exacerbated by beam energy spread and focusing magnet misalignments. For energy spread and alignment tolerances expected for Scorpius, a magnetic tune designed to transport a matched beam is shown to produce minimal corkscrew motion.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3141-3143"},"PeriodicalIF":1.5,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145290225","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 : 2025-09-03DOI: 10.1109/TPS.2025.3602400
Aijun Zhu;Wenrui Wei;Weigang Hou;Huiming Zheng;Cong Hu
A balanced three-value 3-1 encoder for terahertz (THz) metamaterials (MMS) based on graphene plasma-induced transparency (PIT) and phase change material (PCM), for the first time, was proposed. It can achieve 3-1 encoding function in the THz frequency band and belongs to multivalue logic devices. The logic output results can be −1, 0, and 1. The time-domain finite integration (FITD) method was used to simulate and optimize the performance of the encoder. The simulation results show that the device achieves 3-1 encoding function at 2.572 and 4.231 THz (valley of PIT effect), with reflectivity of 93.4% and 93.1%, modulation depth (MD) of 99.9% and 99.8%, extinction ratio (ER) of 12.9 and 9.08 dB, and insertion loss (IL) of 0.02 and 0.15 dB, respectively. When the two encoded outputs of the device are treated as a subset, THz balanced ternary summation operations for pull-up conversion and pull-down conversion can be achieved separately. In addition, the device has excellent sensing performance, with a sensitivity of up to 1.491 THz/RIU in different refractive index environments, and has the characteristic of insensitivity to incident angle, which can be applied in complex encoding and sensing environments. This device can be used in scenarios such as information encryption, data compression, signal anticounterfeiting, and communication protocols. Therefore, this work provides new ideas for the design of THz multivalue logic devices and has certain reference significance in the field of THz communication modulation.
{"title":"A Balanced Ternary 3-1 Encoder of Terahertz Metamaterials and Its Sensing Application","authors":"Aijun Zhu;Wenrui Wei;Weigang Hou;Huiming Zheng;Cong Hu","doi":"10.1109/TPS.2025.3602400","DOIUrl":"https://doi.org/10.1109/TPS.2025.3602400","url":null,"abstract":"A balanced three-value 3-1 encoder for terahertz (THz) metamaterials (MMS) based on graphene plasma-induced transparency (PIT) and phase change material (PCM), for the first time, was proposed. It can achieve 3-1 encoding function in the THz frequency band and belongs to multivalue logic devices. The logic output results can be −1, 0, and 1. The time-domain finite integration (FITD) method was used to simulate and optimize the performance of the encoder. The simulation results show that the device achieves 3-1 encoding function at 2.572 and 4.231 THz (valley of PIT effect), with reflectivity of 93.4% and 93.1%, modulation depth (MD) of 99.9% and 99.8%, extinction ratio (ER) of 12.9 and 9.08 dB, and insertion loss (IL) of 0.02 and 0.15 dB, respectively. When the two encoded outputs of the device are treated as a subset, THz balanced ternary summation operations for pull-up conversion and pull-down conversion can be achieved separately. In addition, the device has excellent sensing performance, with a sensitivity of up to 1.491 THz/RIU in different refractive index environments, and has the characteristic of insensitivity to incident angle, which can be applied in complex encoding and sensing environments. This device can be used in scenarios such as information encryption, data compression, signal anticounterfeiting, and communication protocols. Therefore, this work provides new ideas for the design of THz multivalue logic devices and has certain reference significance in the field of THz communication modulation.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3194-3204"},"PeriodicalIF":1.5,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145290272","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 : 2025-08-27DOI: 10.1109/TPS.2025.3590376
Duolin Shi;Xiaocun Guan;Shaohua Guan;Lida Yuan
The calculation of the trigger timing sequence for multistage coil launcher presents significant challenges due to the intricate model structure and high degree of coupling, which complicates numerical analysis. Typically, the optimal trigger timing sequence for multistage coil launcher is derived through iterative field-circuit coupling simulations utilizing a finite element model (FEM). However, this approach often demands considerable time investment and is not conducive to real-time control of coil launch devices. To facilitate real-time control of coil launch devices using velocity and position parameters, this article conducts an analysis of the circuit and force models associated with multistage coil launcher based on the current filament method (CFM). Building upon the critical trigger formula derived from velocity and position parameters, we optimize the triggering strategy for multistage coil launcher and propose a new trigger formula. The effectiveness of this optimized triggering strategy is validated through a field-circuit coupling simulation model. This method demonstrates an approximate 3% improvement in efficiency compared to traditional critical trigger methods. Ultimately, this strategy provides a theoretical foundation for achieving real-time control over multistage coil launcher triggering systems.
{"title":"Optimization of Trigger Strategy for Multistage Coil Launcher","authors":"Duolin Shi;Xiaocun Guan;Shaohua Guan;Lida Yuan","doi":"10.1109/TPS.2025.3590376","DOIUrl":"https://doi.org/10.1109/TPS.2025.3590376","url":null,"abstract":"The calculation of the trigger timing sequence for multistage coil launcher presents significant challenges due to the intricate model structure and high degree of coupling, which complicates numerical analysis. Typically, the optimal trigger timing sequence for multistage coil launcher is derived through iterative field-circuit coupling simulations utilizing a finite element model (FEM). However, this approach often demands considerable time investment and is not conducive to real-time control of coil launch devices. To facilitate real-time control of coil launch devices using velocity and position parameters, this article conducts an analysis of the circuit and force models associated with multistage coil launcher based on the current filament method (CFM). Building upon the critical trigger formula derived from velocity and position parameters, we optimize the triggering strategy for multistage coil launcher and propose a new trigger formula. The effectiveness of this optimized triggering strategy is validated through a field-circuit coupling simulation model. This method demonstrates an approximate 3% improvement in efficiency compared to traditional critical trigger methods. Ultimately, this strategy provides a theoretical foundation for achieving real-time control over multistage coil launcher triggering systems.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3171-3178"},"PeriodicalIF":1.5,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145290264","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 : 2025-08-26DOI: 10.1109/TPS.2025.3595131
Tianming Liu;Ge Gao;Li Jiang
Asymmetric firing control has the potential to be applied to thyristor converters in high-power magnet power supplies due to its ability to reduce reactive power generation. However, further analyses indicate new issues, including commutation failures, thyristor trigger designs, and others. The converter output characteristics, particularly regarding the dc voltage output and the fundamental reactive power generation, are affected by various commutation processes. In this article, first, theoretical analyses are conducted to reveal the mechanisms of commutations for different firing angle regions. Second, the output characteristics are analyzed with consideration of commutations, focusing on dc output voltage and fundamental reactive power generation. Calculations and simulations are performed to verify these analyses and evaluate the effect of reactive power reduction. The experimental results confirm the principles of asymmetric firing. Finally, the impact of asymmetric firing on relevant subsystems, including thyristors, snubber circuits, and trigger systems, is further discussed. Also, the effect of reactive power reduction is further supported by analyses of parallel converter systems.
{"title":"Research on Commutations of Thyristor Converters Under Asymmetric Firing Control","authors":"Tianming Liu;Ge Gao;Li Jiang","doi":"10.1109/TPS.2025.3595131","DOIUrl":"https://doi.org/10.1109/TPS.2025.3595131","url":null,"abstract":"Asymmetric firing control has the potential to be applied to thyristor converters in high-power magnet power supplies due to its ability to reduce reactive power generation. However, further analyses indicate new issues, including commutation failures, thyristor trigger designs, and others. The converter output characteristics, particularly regarding the dc voltage output and the fundamental reactive power generation, are affected by various commutation processes. In this article, first, theoretical analyses are conducted to reveal the mechanisms of commutations for different firing angle regions. Second, the output characteristics are analyzed with consideration of commutations, focusing on dc output voltage and fundamental reactive power generation. Calculations and simulations are performed to verify these analyses and evaluate the effect of reactive power reduction. The experimental results confirm the principles of asymmetric firing. Finally, the impact of asymmetric firing on relevant subsystems, including thyristors, snubber circuits, and trigger systems, is further discussed. Also, the effect of reactive power reduction is further supported by analyses of parallel converter systems.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3162-3170"},"PeriodicalIF":1.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289546","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 : 2025-08-26DOI: 10.1109/TPS.2025.3597654
Hao Yan;Xuebao Li;Yan Pan;Rui Jin;Zhibin Zhao
Aiming at the insulation testing requirements for high-voltage silicon carbide (SiC) device packaging under bipolar square wave voltage conditions, this article proposes and develops a novel nanosecond-level high-voltage bipolar square wave generator based on cascaded half-bridge submodules. Under a typical capacitive load, the generator achieves a peak-to-peak voltage of 10 kV, an adjustable repetition frequency from dc to 50 kHz, and a duty cycle ranging from 0% to 100%, with a rise time compressed to approximately 39 ns. By combining a series-isolated power supply design with common-mode filtering, the proposed approach significantly reduces common-mode interference under high dv/dt conditions, ensuring high-voltage isolation of the driver stage and improves electromagnetic compatibility. Compared with traditional pulse topologies such as Blumlein lines, linear transformer drivers (LTDs), and Marx generators, the proposed generator excels in flat-top waveform quality, flexible pulsewidth/duty-cycle modulation, and nanosecond-level rising edges. It thus provides a more precise and reliable experimental platform for investigating partial discharge and insulation-aging mechanisms in high-voltage SiC devices.
{"title":"Development of a Nanosecond-Level High-Voltage Bipolar Square Wave Generator for Insulation Testing of SiC Device Packaging","authors":"Hao Yan;Xuebao Li;Yan Pan;Rui Jin;Zhibin Zhao","doi":"10.1109/TPS.2025.3597654","DOIUrl":"https://doi.org/10.1109/TPS.2025.3597654","url":null,"abstract":"Aiming at the insulation testing requirements for high-voltage silicon carbide (SiC) device packaging under bipolar square wave voltage conditions, this article proposes and develops a novel nanosecond-level high-voltage bipolar square wave generator based on cascaded half-bridge submodules. Under a typical capacitive load, the generator achieves a peak-to-peak voltage of 10 kV, an adjustable repetition frequency from dc to 50 kHz, and a duty cycle ranging from 0% to 100%, with a rise time compressed to approximately 39 ns. By combining a series-isolated power supply design with common-mode filtering, the proposed approach significantly reduces common-mode interference under high <italic>dv</i>/<italic>dt</i> conditions, ensuring high-voltage isolation of the driver stage and improves electromagnetic compatibility. Compared with traditional pulse topologies such as Blumlein lines, linear transformer drivers (LTDs), and Marx generators, the proposed generator excels in flat-top waveform quality, flexible pulsewidth/duty-cycle modulation, and nanosecond-level rising edges. It thus provides a more precise and reliable experimental platform for investigating partial discharge and insulation-aging mechanisms in high-voltage SiC devices.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 9","pages":"2323-2333"},"PeriodicalIF":1.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073138","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 : 2025-08-26DOI: 10.1109/TPS.2025.3598886
Henry O’Keeffe;Martin P. Foster;Jonathan N. Davidson
In this work, a dielectric barrier discharge (DBD) reactor power supply designed for operation with a low input voltage is presented. A piezoelectric resonator (PR) is used to provide voltage gain and high efficiency in a small volume for portable (point of use) ozone generation, suitable for the disinfection of surfaces, for example. The power supply was coupled to a small, asymmetrical DBD reactor and achieved an efficiency of 63% and an ozone generation efficacy of 67 g/kWh when operating at 4.4 W. The use of a PR to provide voltage gain has several advantages over, for example, a traditional electromagnetic transformer. The PR has monolithic construction for reliability, is inherently insulated against high voltage due to the ceramic material, can operate up to $300~^{circ }$ C, and its resonant behavior allows the power supply to operate with zero-voltage switching.
{"title":"Piezoelectric-Resonator-Based Power Supply for an Ozone-Generating Dielectric Barrier Discharge Reactor","authors":"Henry O’Keeffe;Martin P. Foster;Jonathan N. Davidson","doi":"10.1109/TPS.2025.3598886","DOIUrl":"https://doi.org/10.1109/TPS.2025.3598886","url":null,"abstract":"In this work, a dielectric barrier discharge (DBD) reactor power supply designed for operation with a low input voltage is presented. A piezoelectric resonator (PR) is used to provide voltage gain and high efficiency in a small volume for portable (point of use) ozone generation, suitable for the disinfection of surfaces, for example. The power supply was coupled to a small, asymmetrical DBD reactor and achieved an efficiency of 63% and an ozone generation efficacy of 67 g/kWh when operating at 4.4 W. The use of a PR to provide voltage gain has several advantages over, for example, a traditional electromagnetic transformer. The PR has monolithic construction for reliability, is inherently insulated against high voltage due to the ceramic material, can operate up to <inline-formula> <tex-math>$300~^{circ }$ </tex-math></inline-formula>C, and its resonant behavior allows the power supply to operate with zero-voltage switching.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3105-3112"},"PeriodicalIF":1.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145289551","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 : 2025-08-26DOI: 10.1109/TPS.2025.3531223
Shuqun Wu;Dawei Shi;Yue Guo;Sude Liu;Qiaojue Liu
The gas temperature of arc plasma is an essential parameter in studies of the motion and extinguishment of arc, the recovery of gas insulation, and electrode erosion caused by arc discharge. This work measured the spatial distribution of the gas temperature by high-speed shadow imaging of the variation of the arc-induced flow field, which was confirmed by the Boltzmann plot method of the emission of the excited states of copper atoms. A typical low-current dc arc from photovoltaic arc faults was generated in the open air. The results showed that the gas temperature near the cathode was higher than that near the anode, which was different from the arc discharge of a high-current dc arc. It was interesting to observe a dispersed high-temperature region in the upper left, away from the cathode, which was independent of the direction of the electrode movement. When the arc current increased, the high-temperature region became elongated and then connected with the cathode. Detailed analysis of the flow field and the radiation light of the arc showed that the high-temperature region was probably caused by the electrode jet phenomenon of arc discharge.
{"title":"Gas Temperature Measurement of Low-Current DC Arc in Air by Shadow Imaging","authors":"Shuqun Wu;Dawei Shi;Yue Guo;Sude Liu;Qiaojue Liu","doi":"10.1109/TPS.2025.3531223","DOIUrl":"https://doi.org/10.1109/TPS.2025.3531223","url":null,"abstract":"The gas temperature of arc plasma is an essential parameter in studies of the motion and extinguishment of arc, the recovery of gas insulation, and electrode erosion caused by arc discharge. This work measured the spatial distribution of the gas temperature by high-speed shadow imaging of the variation of the arc-induced flow field, which was confirmed by the Boltzmann plot method of the emission of the excited states of copper atoms. A typical low-current dc arc from photovoltaic arc faults was generated in the open air. The results showed that the gas temperature near the cathode was higher than that near the anode, which was different from the arc discharge of a high-current dc arc. It was interesting to observe a dispersed high-temperature region in the upper left, away from the cathode, which was independent of the direction of the electrode movement. When the arc current increased, the high-temperature region became elongated and then connected with the cathode. Detailed analysis of the flow field and the radiation light of the arc showed that the high-temperature region was probably caused by the electrode jet phenomenon of arc discharge.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 9","pages":"2342-2350"},"PeriodicalIF":1.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073358","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}
A Fluent-based simulation model was established to explore the anode current density distribution, as well as the internal temperature and velocity fields with three typical anode structures: cylindrical type, Laval type, and constricted type. First, by analyzing the relevant governing equations and theories of the laminar plasma torch, a numerical simulation model based on Fluent was developed, and its validity was verified through experiments. Then, using the constructed model, the temperature and velocity fields within the plasma torch, along with the anode surface current density distribution, were simulated and analyzed. Finally, based on a comparative analysis of the simulation results, optimization suggestions for the anode structure were proposed. The results indicate that: 1) the error between the simulation results and the experimental results of the constructed simulation model is less than 3%; 2) cylindrical-type anode current density > constricted-type anode current density > Laval-type anode current density; 3) the three typical anode structures have little influence on the temperature field within the plasma torch; however, in the anode outlet area, the outlet center temperature of the cylindrical-type anode structure is the lowest, and the radial temperature gradient is the largest; and the outlet central temperature of the Laval-type structure is slightly lower than that of the constricted-type structure, but its radial temperature gradient is the smallest, which is conducive to the uniform dispersion of the plasma flow temperature; and 4) the velocity field corresponding to the cylindrical-type structure is slightly lower than that corresponding to the Laval-type structure and the constricted-type structure. Moreover, when the Laval-type structure is adopted, the velocity in the anode area is only slightly lower than that of the constricted structure.
{"title":"Effects of Anode Structures on the Laminar Plasma Jet Characteristics Based on Fluent Simulation Method","authors":"Xiuquan Cao;Ling Luo;Yong He;Xing Liu;Yi Zhao;Yufeng Tang","doi":"10.1109/TPS.2025.3598054","DOIUrl":"https://doi.org/10.1109/TPS.2025.3598054","url":null,"abstract":"A Fluent-based simulation model was established to explore the anode current density distribution, as well as the internal temperature and velocity fields with three typical anode structures: cylindrical type, Laval type, and constricted type. First, by analyzing the relevant governing equations and theories of the laminar plasma torch, a numerical simulation model based on Fluent was developed, and its validity was verified through experiments. Then, using the constructed model, the temperature and velocity fields within the plasma torch, along with the anode surface current density distribution, were simulated and analyzed. Finally, based on a comparative analysis of the simulation results, optimization suggestions for the anode structure were proposed. The results indicate that: 1) the error between the simulation results and the experimental results of the constructed simulation model is less than 3%; 2) cylindrical-type anode current density > constricted-type anode current density > Laval-type anode current density; 3) the three typical anode structures have little influence on the temperature field within the plasma torch; however, in the anode outlet area, the outlet center temperature of the cylindrical-type anode structure is the lowest, and the radial temperature gradient is the largest; and the outlet central temperature of the Laval-type structure is slightly lower than that of the constricted-type structure, but its radial temperature gradient is the smallest, which is conducive to the uniform dispersion of the plasma flow temperature; and 4) the velocity field corresponding to the cylindrical-type structure is slightly lower than that corresponding to the Laval-type structure and the constricted-type structure. Moreover, when the Laval-type structure is adopted, the velocity in the anode area is only slightly lower than that of the constricted structure.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 10","pages":"3144-3152"},"PeriodicalIF":1.5,"publicationDate":"2025-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145290266","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 : 2025-08-22DOI: 10.1109/TPS.2025.3598042
G. Y. Pan;J. C. Cai;Z. X. Su;X. K. Zhang;Z. Zhang;Z. X. Liang;M. Asad;C. Zhang;L. Zeng;X. C. Lin;P. C. Yin;J. Xu;L. N. Yue;H. R. Yin;Y. Xu;G. Q. Zhao;W. X. Wang;Y. Y. Wei
To realize the miniaturization of RF sources for applications in dynamic nuclear polarization–nuclear magnetic resonance (DNP–NMR) spectroscopy, a compact continuous-wave (CW) 263-GHz extended interaction klystron (EIK) frequency upconverter is designed and proposed in this article, including the high-frequency circuit and a complete compact beam optical system (BOS) based on hybrid permanent magnets. This G-band EIK could be driven by easily accessible W-band signal with power level less than 1 W. A local magnetic field enhancement technology is used in the BOS to allow the beam to be further compressed in the tiny drifting tunnel of output cavity, achieving full cylindrical-beam transmission along the whole hybrid circuit. Particle-in-cell (PIC) simulation results show that the saturated output power of the designed EIK could reach over 250 W at 263 GHz, with an operating beam voltage of 24 kV and a beam current of 0.3 A. In addition, its instantaneous bandwidth is broad enough to meet the requirements of DNP–NMR power source where no instability is observed. The key specifications demonstrate that the designed EIK could stably operate in CW mode. This study is expected to provide new approach for the design of cost-efficient sub-THz EIKs in a compact profile, aiming for DNP–NMR applications and beyond.
{"title":"Demonstration of a Compact CW 263-GHz Extended Interaction Klystron Frequency Upconverter","authors":"G. Y. Pan;J. C. Cai;Z. X. Su;X. K. Zhang;Z. Zhang;Z. X. Liang;M. Asad;C. Zhang;L. Zeng;X. C. Lin;P. C. Yin;J. Xu;L. N. Yue;H. R. Yin;Y. Xu;G. Q. Zhao;W. X. Wang;Y. Y. Wei","doi":"10.1109/TPS.2025.3598042","DOIUrl":"https://doi.org/10.1109/TPS.2025.3598042","url":null,"abstract":"To realize the miniaturization of RF sources for applications in dynamic nuclear polarization–nuclear magnetic resonance (DNP–NMR) spectroscopy, a compact continuous-wave (CW) 263-GHz extended interaction klystron (EIK) frequency upconverter is designed and proposed in this article, including the high-frequency circuit and a complete compact beam optical system (BOS) based on hybrid permanent magnets. This G-band EIK could be driven by easily accessible W-band signal with power level less than 1 W. A local magnetic field enhancement technology is used in the BOS to allow the beam to be further compressed in the tiny drifting tunnel of output cavity, achieving full cylindrical-beam transmission along the whole hybrid circuit. Particle-in-cell (PIC) simulation results show that the saturated output power of the designed EIK could reach over 250 W at 263 GHz, with an operating beam voltage of 24 kV and a beam current of 0.3 A. In addition, its instantaneous bandwidth is broad enough to meet the requirements of DNP–NMR power source where no instability is observed. The key specifications demonstrate that the designed EIK could stably operate in CW mode. This study is expected to provide new approach for the design of cost-efficient sub-THz EIKs in a compact profile, aiming for DNP–NMR applications and beyond.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 9","pages":"2219-2225"},"PeriodicalIF":1.5,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073428","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 : 2025-08-22DOI: 10.1109/TPS.2025.3589221
Bin Zhang;Changlin Zou;Shuqun Wu
This study develops a zero-dimensional kinetic model to investigate the effects of nanosecond pulsed discharge on the ignition characteristics of stoichiometric ethylene–air mixtures. The simulation framework combines ZDPlasKin for plasma kinetics and CHEMKIN for combustion chemistry. At an initial temperature of 1200 K, a pressure of 1.1 atm, and a fixed plasma energy input of 20 mJ/cm3, the results show that the nanosecond discharge significantly shortens the ignition delay time compared to autoignition. The ignition enhancement strongly depends on the reduced electric field $E/N$ , reaching a minimum delay at 200 Td. The primary radicals responsible for promoting ignition—O, H, C2H, and C2H3—are mainly produced through quenching reactions of electronically excited nitrogen species, particularly N2(A) and N2($text{a}^{prime }$ ). Path flux analysis reveals that electron collisions contribute significantly to O formation, while H and C2H3 are predominantly formed via N2 quenching. The variation in radical production with $E/N$ explains the non monotonic trend of ignition delay time.
{"title":"Kinetic Effects of Nanosecond Discharge on the Ignition Delay of Ethylene–Air Mixtures","authors":"Bin Zhang;Changlin Zou;Shuqun Wu","doi":"10.1109/TPS.2025.3589221","DOIUrl":"https://doi.org/10.1109/TPS.2025.3589221","url":null,"abstract":"This study develops a zero-dimensional kinetic model to investigate the effects of nanosecond pulsed discharge on the ignition characteristics of stoichiometric ethylene–air mixtures. The simulation framework combines ZDPlasKin for plasma kinetics and CHEMKIN for combustion chemistry. At an initial temperature of 1200 K, a pressure of 1.1 atm, and a fixed plasma energy input of 20 mJ/cm<sup>3</sup>, the results show that the nanosecond discharge significantly shortens the ignition delay time compared to autoignition. The ignition enhancement strongly depends on the reduced electric field <inline-formula> <tex-math>$E/N$ </tex-math></inline-formula>, reaching a minimum delay at 200 Td. The primary radicals responsible for promoting ignition—O, H, C<sub>2</sub>H, and C<sub>2</sub>H<sub>3</sub>—are mainly produced through quenching reactions of electronically excited nitrogen species, particularly N<sub>2</sub>(A) and N<sub>2</sub>(<inline-formula> <tex-math>$text{a}^{prime }$ </tex-math></inline-formula>). Path flux analysis reveals that electron collisions contribute significantly to O formation, while H and C<sub>2</sub>H<sub>3</sub> are predominantly formed via N<sub>2</sub> quenching. The variation in radical production with <inline-formula> <tex-math>$E/N$ </tex-math></inline-formula> explains the non monotonic trend of ignition delay time.","PeriodicalId":450,"journal":{"name":"IEEE Transactions on Plasma Science","volume":"53 9","pages":"2161-2167"},"PeriodicalIF":1.5,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073187","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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