Studies of the Frequency-Agile Relativistic Magnetron

Li, Tianming; Li, Jiayin; Hu, Biao

doi:10.1109/tps.2012.2189025

Cited by 24 publications

(11 citation statements)

References 10 publications

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“…As a unique plasma source, cold atmospheric plasma (CAP) jet has been widely used in numerous applications, including treatment of living biomaterials for genome mutation of micro-organisms or medical therapy [1][2][3][4][5][6], sterilization of heat-sensitive instruments, decontamination of chemical/ biological warfare agents or nuclear waste [7][8][9], materials surface modifications for various improved performances, e.g. modifications of the polymethyl methacrylate surfaces for improving the flashover performance of the surfaces in vacuum, or enhancement of charge dissipation of the epoxy material surfaces in high voltage electrical equipment [10,11], etc.…”

Section: Introductionmentioning

confidence: 99%

“…Although the plasma jet produced by an α-mode RF discharge has been widely used in actual applications, e.g. in genome mutation breeding of microbes [5,6] and plasma dentistry [17,18], the short plasma jet length and low concentrations of the chemically reactive species in the plasma jet region limit its applications for advanced materials processing in practice. While if the RF-APGDs operate in a γ-mode [14], although the number densities of the chemically reactive species in the plasma jet region can be enhanced significantly with a somewhat lengthening of the plasma jet under a higher RF power input, the gas temperature also increases remarkably.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Khan

et al. 2019

Plasma Sci. Technol.

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Cold atmospheric plasma (CAP) jet has wide applications in various fields including advanced materials synthesis and modifications, biomedicine, environmental protection and energy saving, etc. Appropriate control on the volume, temperature and chemically reactive species concentrations of the CAP jet is of great importance in actual applications. In this paper, an radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma generator with a hybrid cross-linear-field electrode configuration is proposed. The experimental results show that, with the aid of the copper mesh located at the downstream of the traditional co-axial-type plasma generator with a cross-field electrode configuration, a linear field between the inner powered electrode of the traditional plasma generator and the copper mesh can be established. This linerfield can, to some extent, enhance the discharges at the upstream of the copper mesh, resulting in small increments (all less than 12.5%) of the species emission intensities, electron excitation temperatures and gas temperatures by keeping other parameters being unchanged. And due to the intrinsic transparent and conducting features of the grounded copper mesh to the gas flowing, electric current and heat flux of the plasma plumes, a plasma region with higher concentrations of chemically reactive species and larger plasma plume diameters is obtained at the downstream of the grounded copper mesh on the same level of the gas temperature and electron excitation temperature compared to those of the plasma free jet. In addition, the charged particle number densities at the same downstream axial location of the grounded copper mesh decrease significantly compared to those of the plasma free jet. This means that the copper mesh is also, to some extent, helpful for separating the chemically reactive neutral species from the charged particles inside a plasma environment. The preceding results indicate that the cross-linear-field electrode configuration of the plasma generator is an effective approach for tuning the characteristics of the RF-APGD plasma jet in order to obtain an appropriate combination of the plasma jet properties with higher chemically reactive species concentrations, especially relative higher number densities of neutral species, larger plasma volumes and lower gas temperatures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Khan

et al. 2019

Plasma Sci. Technol.

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“…In order to compare the effects of two kinds of flake graphite cathodes on the performance of RMs, experiments were carried out on the S-band RM, which was reported in our previous studies [32]. This RM has the characteristics of stable operation, high power and pure output microwave mode, and the π mode operating frequency of this RM is 2.955GHz.…”

Section: Performance Experimentsmentioning

confidence: 99%

“…The microwave measurement system was the same as that in reference [32]. As shown in Figure .2(b), the microwave generated by the magnetron was extracted through the rectangular waveguide and output through the horn antenna.…”

Section: Performance Experimentsmentioning

confidence: 99%

Study on Flake Graphite Cathode Surface Microstructure in Relativistic Magnetrons

Chen

Jiang²,

Yang

et al. 2023

IEEE J. Electron Devices Soc.

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Flake graphite has excellent explosive electron emission performance for its plenty surface micro-bulges and high graphitization degree, but its advantages have rarely been studied in relativistic magnetrons. In this paper, flake graphite cathodes with different fineness were used in coaxial diodes and relativistic magnetrons, and the influence of the surface microstructure of the flake graphite cathode on the relativistic magnetron performance is demonstrated for the first time. The result showed that the graphite microstructure mainly affected the initiation stage of explosive emission. Moreover, the delay time is determined by the degree of graphitization and the surface microstructure of graphite, and the surface microstructure plays a major role. Under the applied voltage of ∼ 330kV-∼ 490kV, The finer flake graphite possessed a shorter emission delay and facilitated the microwave excitation. The excitation time of finer flake graphite is ∼ 3ns, and ∼ 5ns for lager flake graphite. After several operations of the relativistic magnetron, the edges of flake graphite were blunted, and the surface of the flake graphite appeared droplet-like areas formed by anode atom sputtering. This work reveals the advantages of the finer flake graphite cathode in the fast priming of the relativistic magnetron, thus shedding new light on cathode design of the relativistic magnetron.

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“…However, except for the relativistic magnetron (RM), HPM sources that can generate circularly polarized microwaves without using mode converters are rarely reported. In fact, RMs can generate separately various microwave modes, such as a TE 01 mode 1 , 2 , a linearly polarized TE n1 (n ≥ 1 is an integer) mode 1 – 5 , or a circularly polarized TE n1 (n ≥ 2 is an integer) mode 4 – 7 in circular waveguide, or a TE 10 mode in rectangular waveguide 8 , 9 . Until 2012, RMs with all cavity-magnetron axial extraction technique were investigated with numerical simulation 10 and it has become possible to generate TEM modes in a coaxial waveguide.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigations on radiation generation of TEM, linearly or circularly polarized TEn1 coaxial waveguide mode in relativistic magnetron

Shi

Qian

Wang

et al. 2017

Sci Rep

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The physical mechanism of the radiation generation of all possible output modes of the relativistic magnetron (RM) with all cavity-magnetron axial extraction technique is theoretically analysed, and the necessary conditions for generating these modes are obtained respectively. Assuming that n 0 is the number of the electron spokes, N ≥ 4 as the total number of the cavities is an even number, and k is a nonnegative integer, some conclusions can be drawn as follows. If n 0 = kN is true, no mode can be excited in the coaxial waveguide; if n 0 = (2k + 1)N/4 is true, the linearly polarized modes can be excited in the coaxial waveguide; if n 0 = (4k + 2)N/4 is true, the TEM mode and the linearly polarized modes can be excited in the coaxial waveguide; if n 0 takes other value, the left and right circularly polarized modes can be excited in the coaxial waveguide and the directions of rotation of the circularly polarized modes can be reversed with the reversion of the direction of rotation of the electron spokes; in addition, some other regular characteristics of the corresponding mode excitation are presented in detail in this paper. Such unique attractive properties that have been verified by the cold and hot simulations in this paper make it possible for this type of RM to meet application requirements of various high power microwave (HPM) modes.

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Studies of the Frequency-Agile Relativistic Magnetron

Cited by 24 publications

References 10 publications

Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Study on Flake Graphite Cathode Surface Microstructure in Relativistic Magnetrons

Theoretical investigations on radiation generation of TEM, linearly or circularly polarized TEn1 coaxial waveguide mode in relativistic magnetron

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