Theory of Filamentary Plasma Array Formation in Microwave Breakdown at Near-Atmospheric Pressure

Nam, Sang Ki; Verboncoeur, John P.

doi:10.1103/physrevlett.103.055004

Cited by 94 publications

(62 citation statements)

References 13 publications

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“…At 1 atm, the plasma filaments are obtained by the microwave incident, and the distance between each filament is about λ/5, showing well agreement with the experimental and numerical studies [1][2][3][6][7][8] (Fig. 1(a)).…”

Section: Plasma Structures At 1 Atm and 0006 Atmsupporting

confidence: 84%

Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

Takahashi

Ohnishi

2016

J. Phys.: Conf. Ser.

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Abstract.A one-dimensional compressible fluid calculation was coupled with a finitedifference time-domain code and a particle-in-cell code with collision to reproduce propagation of electromagnetic wave, ionization process of plasma, and shock wave formation in atmospheric microwave discharge. Plasma filaments are driven toward the microwave source at 1 atm, and the distance between each filament is one-fifth of the wavelength of the incident microwave. The strong shock wave is generated due to the high plasma density at the atmospheric pressure. A simple analysis of the microwave propagation into the plasma shows that cut-off density of the microwave becomes smaller with the pressure decrease in a collisional plasma. At the lower pressure, the smaller density plasma is obtained with a diffusive pattern because of the smaller cut-off density and the larger diffusion effect. In contrast with the 1-atm case, the weak shock wave is generated at a rarefied condition, which lowers performance of microwave thruster. IntroductionSignificant advancement for space transportation is needed to utilize an outer space as academic study, space travel, military defense, weather observation and so on. Recently, microwave propulsion system has been investigated to launch a small satellite with saving operation cost by high-power energy transmission from a microwave oscillator established on a ground. The irradiated microwave is focused by a parabolic mirror installed on the vehicle, and the intense microwave generates a plasma with sustaining a strong shock wave which supplies an impulsive thrust through interactions with the rocket thruster. In past experiments of the plasma formation by the microwave [1][2][3], filamentary arrays of the plasma were observed in contrast with a bulk plasma obtained in a laser breakdown [4]. The plasma filaments propagate toward the microwave source at km/s-order velocity, and the distance between each filament is about one-quarter of the incident microwave wavelength. However, at the lower pressure, the plasma cannot form the filamentary structure, and the measured impulse of the microwave rocket drastically drops down [2,3]. Detailed mechanism of the thrust decrease is not identified by the past experiments; therefore, the plasma and shock generations by the microwave discharge should be examined.In this study, we have developed a one-dimensional integrated simulator by combining a finitedifference time-domain (FDTD) code, a particle-in-cell with Monte Calro collision (PIC-MCC) code, and a computational fluid dynamics (CFD) code to assess the shock wave and plasma formations by the microwave discharge. We then numerically assess the ambient pressure effects for the plasma and shock wave structures, and specify the mechanism of the thrust decrease at the lower pressure.

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Section: Plasma Structures At 1 Atm and 0006 Atmsupporting

confidence: 84%

Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

Takahashi

Ohnishi

2016

J. Phys.: Conf. Ser.

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“…The formation of these structures can be related with the formation of the electricfield antinodes before the moving ionization front as a result of reflection of the incident electromagnetic emission from the gas-discharge plasma. To confirm this hypothesis, a series of numerical calculations have been performed in the last decade to study the dynamics of a gas discharge in the field of a plane electromagnetic wave with intensity exceeding the breakdown value [6][7][8][9][10][11][12]. In these calculations, regular discharge structures similar to those observed in the experiment were obtained for the seed electrons localized in a small region of space.…”

Section: Introductionmentioning

confidence: 83%

Initial Stage of the Microwave Ionization Wave Within a 1D Model

Semenov

Rakova

Glyavin

et al. 2016

Radiophys Quantum El

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UDC 537.52The dynamics of the microwave breakdown in a gas is simulated numerically within a simple 1D model which takes into account such processes as the impact ionization of gas molecules, the attachment of electrons to neutral molecules, and plasma diffusion. Calculations are carried out for different spatial distributions of seed electrons with account for reflection of the incident electromagnetic wave from the plasma. The results reveal considerable dependence of the ionization wave evolution on the relation between the field frequency and gas pressure, as well as on the existence of extended rarefied halo of seed electrons. At relatively low gas pressures (or high field frequencies), the breakdown process is accompanied by the stationary ionization wave moving towards the incident electromagnetic wave. In the case of a high gas pressure (or a relatively low field frequency), the peculiarities of the breakdown are associated with the formation of repetitive jumps of the ionization front.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In recent years, a plasma filamentation was reported to occur during microwave irradiations. Hidaka et al 1 experimentally obtained a filamentary plasma by lens focusing of the microwaves generated by a pulsed 1.5 MW, 110 GHz gyrotron.…”

confidence: 99%

“…In a number of studies, numerical simulations using a fluid or particle model coupled with electromagnetic wave propagation were conducted to reproduce the self-organized pattern observed under the overcritical condition. [8][9][10][11][12][13][14][15][16][17] In these simulations, instead of solving the beam-focusing process by the lens, the rms electric field of the incident beam (E 0,rms ) was set to be above E c to reproduce the plasma formation sustained by the overcritical field at the focal point. The simulation results indicate that a quasi-standing wave is induced in front of the plasma because microwaves reflected by the dense plasma overlap the incident microwave.…”

confidence: 99%

Joule-heating-supported plasma filamentation and branching during subcritical microwave irradiation

2017

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Theory of Filamentary Plasma Array Formation in Microwave Breakdown at Near-Atmospheric Pressure

Cited by 94 publications

References 13 publications

Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

Shock Formation by Plasma Filaments of Microwave Discharge under Atmospheric Pressure

Initial Stage of the Microwave Ionization Wave Within a 1D Model

Joule-heating-supported plasma filamentation and branching during subcritical microwave irradiation

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