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

Takahashi, M.; Kageyama, Yoshiaki; Ohnishi, Naofumi

doi:10.1063/1.4983569

Cited by 22 publications

(26 citation statements)

References 22 publications

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“…Takahashi et al . 21 discussed structure formation with the ionization model. However, this model, in which the expansion wave is in front of the ionization front, has not yet been verified experimentally.…”

Section: Introductionmentioning

confidence: 99%

Observation of a comb-shaped filamentary plasma array under subcritical condition in 303-GHz millimetre-wave air discharge

Fukunari

Tanaka

Shinbayashi

et al. 2019

Sci Rep

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Gas breakdown in the millimetre-wave frequency band is an interesting phenomenon in nonlinear dynamics such as self-organized structure formation. We observed the transition between two types of filamentary plasma arrays in air discharge driven by a 303-GHz millimetre wave. Plasma is ignited at a parabolic mirror’s focal point in the overcritical condition. One array parallel to the electric field vector appears with a spacing of λ/4 at the focal point. Filaments then separate into plasma lumps ~10 μs after ignition. At 20 μs, a new comb-shaped array grows in the subcritical condition. Filaments are parallel to the incident beam with spacing of 0.96 λ and elongate towards the incident beam. This comb-shaped array appears only in the electric field plane; bulk plasma with a sharp vertex forms in the magnetic field plane. This array is created by a standing wave structure generated by waves diffracted from the plasma surface. Filamentary plasma array formations can influence the energy absorption by the plasma, which is important for engineering applications such as beamed energy propulsion.

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Section: Introductionmentioning

confidence: 99%

Observation of a comb-shaped filamentary plasma array under subcritical condition in 303-GHz millimetre-wave air discharge

Fukunari

Tanaka

Shinbayashi

et al. 2019

Sci Rep

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“…However, the correct propagation physics of the ionization front was not captured by Nakamura's model because the change of the breakdown threshold was not validated. In 2017, Takahashi et al numerically reproduced the plasma filamentation and branching structure during subcritical microwave beam irradiation based on the effective diffusion model proposed by Boeuf et al when it was coupled with a compressible fluid dynamics simulation for neutral particles and Maxwell's equation [88]. Coupling simulation between the plasma and the neutral particles can capture changes of the electron's transport coefficient induced by variation of the neutral particle density.…”

Section: Breakdown Physics During a Subcritical Beam Irradiationmentioning

confidence: 99%

Discharge from a high-intensity millimeter wave beam and its application to propulsion

Takahashi

Komurasaki

2018

Advances in Physics: X

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Many experimental and numerical studies have been conducted to elucidate the fascinating physics of plasma formation and shock wave propagation during millimeter wave beam irradiation outputted from a high averagepower gyrotron. A microwave-rocket system for rocket launching was proposed as an engineering application using an intense millimeter wave beam. Flight demonstrations and thrust measurements were repeated while changing the ambient pressure, beam power density, beam profile, and vehicle shape. We reviewed reports of experimental and computational studies to assess information on plasma propagation and compressible fluid dynamics induced by the millimeter wave beam. Earlier experiments and simulations of rocket launching were also examined for this study.

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“…The comb-shaped filamentary structure was formed at much lower intensity than the breakdown threshold. Takahashi et al [46,47] proposed a numerical model considering compressibility of the ambient gas. Results showed that expansion behind a precursor shock wave enhances the effective field intensity to near the threshold in front of the plasma.…”

Section: Numerical Simulation Of Millimeter-wave Discharge Plasmamentioning

confidence: 99%

“…Millimeter-wave discharge occurs even at the beam intensity far below breakdown threshold [44]. This discharge cannot be explained by field concentration nor by ambient gas expansion behind a blast wave [45,46] and requires other Figure 8: Ionization-front propagation velocity in an atmospheric millimeter-wave discharge [34,36] and laser discharge [37][38][39]. [44].…”

Section: Numerical Simulation Of Millimeter-wave Discharge Plasmamentioning

confidence: 99%

Development of a Novel Launch System Microwave Rocket Powered by Millimeter-Wave Discharge

Komurasaki

Tabata

2018

International Journal of Aerospace Engineering

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This paper presents the state of art of Microwave Rocket development and related researches on atmospheric discharge in a high-power millimeter-wave beam. Its operational mechanisms, thruster design, history of development, and flight path and cost analyses are introduced along with millimeter-wave discharge observations and numerical simulations. A thruster model of 126 g weight with no on-board propellant was launched to 1.2 m altitude using a 1 MW class gyrotron. A flight analysis that shows 77% cost reduction is possible using Microwave Rocket as the first stage of H-IIB heavy. A millimeter-wave discharge with unique plasma structure such as a quarter-wavelength microstructure and a comb-shaped filamentary structure was observed and reproduced by a two-dimensional numerical model.

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

Cited by 22 publications

References 22 publications

Observation of a comb-shaped filamentary plasma array under subcritical condition in 303-GHz millimetre-wave air discharge

Observation of a comb-shaped filamentary plasma array under subcritical condition in 303-GHz millimetre-wave air discharge

Discharge from a high-intensity millimeter wave beam and its application to propulsion

Development of a Novel Launch System Microwave Rocket Powered by Millimeter-Wave Discharge

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