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19 pages, 27035 KiB

Open AccessArticle

A Highly Stabilized Current Source Topology with Slope Compensation for a High-Power Microwave Guiding Coil

by Dandi Zhang, Hongfa Ding, Zhou He, Wentao Zhou and Ziqi Zhang

Electronics 2025, 14(4), 739; https://doi.org/10.3390/electronics14040739 - 13 Feb 2025

Viewed by 542

For the waveguide coil in a High-Power Microwave (HPM) source, a strong repetitive Flat-top Pulsed Magnetic Field (FTPMF) is needed, which requires the power supply system to generate a high load current (3∼5 kA) with high stability (<1000 ppm) and a long pulse-width [...] Read more.

For the waveguide coil in a High-Power Microwave (HPM) source, a strong repetitive Flat-top Pulsed Magnetic Field (FTPMF) is needed, which requires the power supply system to generate a high load current (3∼5 kA) with high stability (<1000 ppm) and a long pulse-width (15∼20 ms). To achieve this, this article proposes a novel topology which includes a capacitor bank as the main power supply to guarantee a long pulse-width, combined with an active current compensator to regulate the load current precisely. A PI control scheme with slope compensation is used to solve the current fluctuation caused by capacitor switching. The novel topology also features a fast rising and falling time, thus it is suitable for repetitive working applications. The parameters of the topology are calculated by analysis to guarantee the working condition of a 45 GHz HPM source, and the operating principle of this topology is verified through low-power-scale experiments. Full article

(This article belongs to the Special Issue Advances in Pulsed-Power and High-Power Electronics)

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12 pages, 5737 KiB

Open AccessArticle

Modeling of 2-D Periodic Array of Dielectric Bars with a Low Reflection Angle for a Wind Tunnel High-Power Microwave Experiment

by Rong Bao, Yang Tao and Yongdong Li

Appl. Sci. 2024, 14(23), 10876; https://doi.org/10.3390/app142310876 - 24 Nov 2024

Viewed by 722

Abstract

Two-dimensional periodic dielectric bars have potential applications in high-power microwave (HPM) radiation effect experiments performed in wind tunnels. Such a bar is designed to consist of two types of dielectric materials, and two lined-up blocks can be considered as a period along the [...] Read more.

Two-dimensional periodic dielectric bars have potential applications in high-power microwave (HPM) radiation effect experiments performed in wind tunnels. Such a bar is designed to consist of two types of dielectric materials, and two lined-up blocks can be considered as a period along the bar. Under plane excitation, the theoretical period length of the beat wave pattern fits well with the simulation result, which requires modifying the previously presented field-matching method. The phase distribution on the cross-section can be non-uniform when two different guiding modes are excited independently and propagate along different materials. Directional reflection with a low reflection angle can be obtained by reasonably choosing the parameters of the dielectric array. The designed array can decrease the returned-back microwave power toward the microwave source by 6 dB according to the numerical simulation, which included the wind tunnel, the input antenna, the test target, and the reflect array in one model. Full article

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12 pages, 8273 KiB

Open AccessArticle

A Compact V-Band Transit Time Oscillator with Reflective Modulation Cavity

by Zulong Chen, Lei Wang, Junpu Ling, Lili Song, Juntao He, Jinmei Yao and Weili Xu

Electronics 2024, 13(16), 3290; https://doi.org/10.3390/electronics13163290 - 19 Aug 2024

Viewed by 907

Abstract

Improving compactness is essential for high-power microwave (HPM) sources. In this paper, a novel reflective modulation cavity is proposed and investigated in a V-band relativistic coaxial transit-time oscillator (RCTTO). The cold cavity analyses and particle-in-cell simulations show that the reflective modulation cavity has [...] Read more.

Improving compactness is essential for high-power microwave (HPM) sources. In this paper, a novel reflective modulation cavity is proposed and investigated in a V-band relativistic coaxial transit-time oscillator (RCTTO). The cold cavity analyses and particle-in-cell simulations show that the reflective modulation cavity has larger reflection coefficients of TEM mode and stronger electron beam modulation capability when compared with a uniform modulation cavity. When the input diode voltage is 391 kV, the beam current is 4.91 kA, and when the guiding magnetic field is 0.6 T, the compact V-band RCTTO produces an output microwave power of 518 MW (conversion efficiency of 27.0%). Compared with the original RCTTO, the compact V-band RCTTO featuring a reflective modulation cavity exhibits a 24.8% increase in output power and a 5.4% improvement in efficiency, and the axial length of the magnetic field uniform region is reduced by 24.2%. The compact V-band RCTTO also demonstrates a broad operation voltage range, indicating potential for stable operation with voltage fluctuations in experiments. Furthermore, the reflective modulation cavity can be integrated into other high-frequency O-type HPM devices to enhance compactness, thereby diminishing the demands on the magnetic field region, which is advantageous for the future permanent packaging of HPM sources. Full article

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11 pages, 2084 KiB

Open AccessArticle

Nonlinear Transmission Line Performance as a Combined Pulse Forming Line and High-Power Microwave Source as a Function of Line Impedance

by Travis D. Crawford and Allen L. Garner

Appl. Sci. 2022, 12(20), 10305; https://doi.org/10.3390/app122010305 - 13 Oct 2022

Cited by 8 | Viewed by 3350

Abstract

Nonlinear transmission lines (NLTLs) offer compact, low-cost, all solid-state high-power microwave (HPM) generation. This article experimentally investigates the RF output power for composite-based 10, 25, and 50 Ω NLTLs used as a combined pulse forming line and HPM source. We manufactured coaxial NLTLs [...] Read more.

Nonlinear transmission lines (NLTLs) offer compact, low-cost, all solid-state high-power microwave (HPM) generation. This article experimentally investigates the RF output power for composite-based 10, 25, and 50 Ω NLTLs used as a combined pulse forming line and HPM source. We manufactured coaxial NLTLs containing 10% barium strontium titanate and 15% nickel zinc ferrite encased in polydimethylsiloxane. The output voltage and power in the time and frequency domains, respectively, showed that the 10 Ω NLTL generated the greatest RF output. The 25 Ω NLTL generated greater output power from 500–1100 MHz than the 50 Ω NLTL. This occurs because reducing the NLTL impedance induces a larger transient current for a given charging voltage. This transient current corresponds to a stronger transient magnetic field, which facilitates magnetic moment alignment to allow for coherent magnetic moment rotation to occur. This setup eliminates the separate pulse forming network and magnetic field bias that typically occurs in other NLTL systems, which provides additional flexibility in tuning the NLTL impedance and reducing device footprint. Full article

(This article belongs to the Special Issue Advances in Solid-State Pulsed Power Applications)

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12 pages, 3878 KiB

Open AccessArticle

Investigation of the Optimum Diameter of the Ring Reflector for an Axial Virtual Cathode Oscillator

by Wan-Il Kim, Se-Hoon Kim and Kwang-Cheol Ko

Electronics 2022, 11(13), 2002; https://doi.org/10.3390/electronics11132002 - 26 Jun 2022

Viewed by 1797

Abstract

The optimum hole diameter of a ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator) to enhance its microwave power. The ring reflector enhances the microwave power from the axial vircator by forming a cavity. The ring reflector was installed [...] Read more.

The optimum hole diameter of a ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator) to enhance its microwave power. The ring reflector enhances the microwave power from the axial vircator by forming a cavity. The ring reflector was installed 9 mm behind the anode. The optimum hole diameter of the ring reflector was analyzed through simulations and experiments by changing the diameter from 60 mm to 160. PIC simulations show that the maximum peak microwave power was generated when the hole diameter was 116 mm and enhanced by 210%. The experiments show similar results to the simulations. The largest peak maximum power was 23.67 MW when the hole diameter was 120 mm. The simulations show that the dominant microwave frequency was formed between 5.33 GHz and 6.7 GHz. The experiments show that the dominant microwave frequency was formed between 5.3 GHz and 5.8 GHz. The frequency trend was approximately similar to that of the simulation results. However, the trend depending on the hole diameter was not as obvious as in the simulations. Although the frequency change was not as clear as in the simulations, experiments show that the hole diameter of the ring reflector affects the vircator operation. Full article

(This article belongs to the Special Issue New Techniques and Components for Microwave and Radiofrequency Applicator Design)

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15 pages, 5914 KiB

Open AccessArticle

Study of Self-Heating and High-Power Microwave Effects for Enhancement-Mode p-Gate GaN HEMT

by Yingshuo Qin, Changchun Chai, Fuxing Li, Qishuai Liang, Han Wu and Yintang Yang

Micromachines 2022, 13(1), 106; https://doi.org/10.3390/mi13010106 - 9 Jan 2022

Cited by 21 | Viewed by 4918

Abstract

The self-heating and high-power microwave (HPM) effects that can cause device heating are serious reliability issues for gallium nitride (GaN) high-electron-mobility transistors (HEMT), but the specific mechanisms are disparate. The different impacts of the two effects on enhancement-mode p-gate AlGaN/GaN HEMT are first [...] Read more.

The self-heating and high-power microwave (HPM) effects that can cause device heating are serious reliability issues for gallium nitride (GaN) high-electron-mobility transistors (HEMT), but the specific mechanisms are disparate. The different impacts of the two effects on enhancement-mode p-gate AlGaN/GaN HEMT are first investigated in this paper by simulation and experimental verification. The simulation models are calibrated with previously reported work in electrical characteristics. By simulation, the distributions of lattice temperature, energy band, current density, electric field strength, and carrier mobility within the device are plotted to facilitate understanding of the two distinguishing mechanisms. The results show that the upward trend in temperature, the distribution of hot spots, and the thermal mechanism are the main distinctions. The effect of HPM leads to breakdown and unrecoverable thermal damage in the source and drain areas below the gate, while self-heating can only cause heat accumulation in the drain area. This is an important reference for future research on HEMT damage location prediction technology and reliability enhancement. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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11 pages, 4232 KiB

Open AccessArticle

Experimental Investigation into the Optimum Position of a Ring Reflector for an Axial Virtual Cathode Oscillator

by Se-Hoon Kim, Chang-Jin Lee, Wan-Il Kim and Kwang-Cheol Ko

Electronics 2021, 10(16), 1878; https://doi.org/10.3390/electronics10161878 - 5 Aug 2021

Cited by 7 | Viewed by 2605

Abstract

A ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator). The ring reflector was installed behind the mesh anode of the axial vircator to enhance the microwave power output by forming a resonant cavity and increasing the electron beam to [...] Read more.

A ring reflector was experimentally investigated using an axial virtual cathode oscillator (vircator). The ring reflector was installed behind the mesh anode of the axial vircator to enhance the microwave power output by forming a resonant cavity and increasing the electron beam to microwave energy conversion efficiency. The optimum position of the ring reflector is analyzed through simulations and experiments by varying the anode to reflector distance from 6 mm to 24 mm in 3 mm steps. PIC simulations show that the ring reflector enhances the microwave power of the axial vircator up to 220%. Experiments show that the microwave power from the axial vircator without the ring reflector is 11.22 MW. The maximum average peak microwave power of the axial vircator with the ring reflector is 25.82 MW when the anode to ring reflector distance is 18 mm. From the simulations and experiments, it can be seen that the ring reflector yields decaying enhancement that is inversely proportional to the anode to ring reflector distance and there is no noticeable microwave enhancement after 24 mm. The frequency range attained from the simulations and experiments is 5.8 to 6.7 GHz and 5.16 to 5.8 GHz, respectively. The difference between the simulation and experimental results is due to the error in the anode to cathode gap distance. Although the frequency is slightly changed, the ring reflector seems to have no influence on the frequency of the generated microwave. Full article

(This article belongs to the Special Issue Design, Technologies and Applications of High Power Vacuum Electronic Devices from Microwave to THz Band)

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13 pages, 4871 KiB

Open AccessArticle

A Compact Modular 5 GW Pulse PFN-Marx Generator for Driving HPM Source

by Haoran Zhang, Ting Shu, Shifei Liu, Zicheng Zhang, Lili Song and Heng Zhang

Electronics 2021, 10(5), 545; https://doi.org/10.3390/electronics10050545 - 26 Feb 2021

Cited by 28 | Viewed by 7227

Abstract

A compact and modular pulse forming network (PFN)-Marx generator with output parameters of 5 GW, 500 kV, and 30 Hz repetition is designed and constructed to produce intense electron beams for the purpose of high-power microwave (HPM) generation in the paper. The PFN-Marx [...] Read more.

A compact and modular pulse forming network (PFN)-Marx generator with output parameters of 5 GW, 500 kV, and 30 Hz repetition is designed and constructed to produce intense electron beams for the purpose of high-power microwave (HPM) generation in the paper. The PFN-Marx is composed by 22 stages of PFN modules, and each module is formed by three mica capacitors (6 nF/50 kV) connected in parallel. Benefiting from the utilization of mica capacitors with high energy density and a mini-trigger source integrated into the magnetic transformer and the magnetic switch, the compactness of the PFN-Marx system is improved significantly. The structure of the PFN module, the gas switch unit, and the connection between PFN modules and switches are well designed for modular realization. Experimental results show that this generator can deliver electrical pulses with the pulse width of 100 ns and amplitude of 500 kV on a 59-ohm water load at a repetition rate of 30 Hz in burst mode. The PFN-Marx generator is fitted into a cuboid stainless steel case with the length of 80 cm. The ratio of storage energy to volume and the ratio of power to weight of the PFN-Marx generator are calculated to be 6.5 J/L and 90 MW/kg, respectively. Furthermore, utilizing the generator to drive the transit time oscillator (TTO) at a voltage level of 450 kV, a 100 MW microwave pulse with the pulse width of 20 ns is generated. Full article

(This article belongs to the Special Issue Design, Technologies and Applications of High Power Vacuum Electronic Devices from Microwave to THz Band)

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21 pages, 2649 KiB

Open AccessReview

Methods of Protecting Buildings against HPM Radiation—A Review of Materials Absorbing the Energy of Electromagnetic Waves

by Krzysztof Majcher, Michał Musiał, Wojciech Pakos, Adrian Różański, Maciej Sobótka and Tomasz Trapko

Materials 2020, 13(23), 5509; https://doi.org/10.3390/ma13235509 - 3 Dec 2020

Cited by 22 | Viewed by 4470

Abstract

The pulsed high power microwave (HPM) technology has been developed worldwide for over 20 years. The sources of HPM pulses are a weapon of mass destruction. They pose danger especially to computer and telecommunications equipment and systems, both the military and civilian ones. [...] Read more.

The pulsed high power microwave (HPM) technology has been developed worldwide for over 20 years. The sources of HPM pulses are a weapon of mass destruction. They pose danger especially to computer and telecommunications equipment and systems, both the military and civilian ones. This paper presents a survey of literature on electromagnetic wave radiation absorbing and shielding materials to be used in construction. Relevant protective measures should include the shielding of buildings or their parts and the absorption of radiation by building envelopes and their elements. The main focus is on the possibilities of improving the shielding and absorptive properties of common construction materials, such as concrete, mortars and synthetic resins. The survey covers the following groups of materials: carbon-based admixtures, nickel powder, iron powders, ferrites, magnetite and polymers. The final part of the survey is devoted to hybrid foam microwave absorbers in which the shape of the material’s inner structure and that of its surface play a special role. Full article

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14 pages, 5419 KiB

Open AccessFeature PaperReview

Experiments Designed to Study the Non-Linear Transition of High-Power Microwaves through Plasmas and Gases

by Yakov E. Krasik, John G. Leopold, Guy Shafir, Yang Cao, Yuri P. Bliokh, Vladislav V. Rostov, Valery Godyak, Meytal Siman-Tov, Raanan Gad, Amnon Fisher, Vladimir Bernshtam, Svetlana Gleizer, Denis Zolotukhin and Yakov Slutsker

Plasma 2019, 2(1), 51-64; https://doi.org/10.3390/plasma2010006 - 8 Mar 2019

Cited by 4 | Viewed by 4350

Abstract

The interaction of powerful sub-picosecond timescale lasers with neutral gas and plasmas has stimulated enormous interest because of the potential to accelerate particles to extremely large energies by the intense wakefields formed and without being limited by high accelerating gradients as in conventional [...] Read more.

The interaction of powerful sub-picosecond timescale lasers with neutral gas and plasmas has stimulated enormous interest because of the potential to accelerate particles to extremely large energies by the intense wakefields formed and without being limited by high accelerating gradients as in conventional accelerator cells. The interaction of extremely high-power electromagnetic waves with plasmas is though, of general interest and also to plasma heating and wake-field formation. The study of this subject has become more accessible with the availability of sub-nanosecond timescale GigaWatt (GW) power scale microwave sources. The interaction of such high-power microwaves (HPM) with under-dense plasmas is a scale down of the picosecond laser—dense plasma interaction situation. We present a review of a unique experiment in which such interactions are being studied, some of our results so far including results of our numerical modeling. Such experiments have not been performed before, self-channeling of HPM through gas and plasma and extremely fast plasma electron heating to keV energies have already been observed, wakefields resulting from the transition of HPM through plasma are next and more is expected to be revealed. Full article

(This article belongs to the Special Issue High-Power Microwave and Plasma Interactions)

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