Microwave electrothermal thruster performance in helium gas

Whitehair, S. J.; Asmussen, J.; Nakanishi, S.

doi:10.2514/3.22965

Cited by 42 publications

(7 citation statements)

References 7 publications

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“…Values required by equations (17) and 18 Based on these studies, adesign will be developedfor botha microwaveandan electronbeam pumpedcoppervaporlasersystem for a production-scale uraniumatomicvaporlaserisotope separationfacility.…”

Section: Resultsmentioning

confidence: 99%

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Electron density and collision frequency of microwave resonant cavity produced discharges. [Progress report]

McColl¹,

Brooks²,

Brake³

1992

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;'-' _ UNLIMt'H::ilgo_J J microwave (2.45 GHz) discharges produced in an Asmussen resonant cavity. Double Langmuir probes, placed directly in the discharge at the point where the radial electric field is zero, act as a comparison with the analytic diagnostics. Microwave powers ranging from 30 to 100 watts produce helium and nitrogen discharges with pressures ranging from 0.5 to 6 tort. Analysis of the data predicts electron temperatures from 5 to 20 eV, electron densities from 1011 to 3×10 t2 cm-3, and collision frequencies from 109 to 10II sec'l, l I. INTRODUUHON Microwave resonant cavity discharges and electron cyclotron resonance (ECR) discharges have become increasingly useful in industrial processes. The low pressure, low ion energy characteristics of ECR discharges make them promising alternatives to radio frequency coupled devices in the field of plasma processing of materials. Due to the inherent use of microwaves in ECR discharges, ECR designs utilizing microwave resonant cavity discharges are being extensively studied for use in plasma processing and thin film deposition 1. Resonant cavity discharges have many additional applications other than materials processing, such as fluorescent excimer lamp systems2,3 and as a possible laser medium4. Due to the lack of electrodes, resonant cavities are very durable yet simple in design and operation. The availability of inexpensive microwave components at 2.45 GHz is also an attractive feature. Prior to 1970, the electromagnetics of microwave resonant cavities perturbed by discharges have been extensively studied.5-22 An article published in 1946 by 3C. Slater5 extensively details research on microwave electronics completed during World War II at the Massachusetts Institute of Technology. The article details the effects that an arbitrary conductance places on a microwave resonant cavity. The techniques presented by Slater were then applied specifically to plasma discharges. _-g These initial techniques were actually used with repet_,ively pulsed discharges, either formed by the electxomagnetic fields within the cavity or produced externally. In a series of four papers by S.C. Brown and coworkers, 9-12 the Slater technique was extensively detailed, as well as its applications as an electron density and collision frequency

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Section: Resultsmentioning

confidence: 99%

“…The electromagnetic fields in a resonant cavity are easily disturbed. where M+ is the ion mass, Is is the saturation current, Ap is the surface area of the probe, and Te is the electron temperature as found in equation (17). By the quasi-neutrality assumption, the electron density is estimatet_ to be equal to the ion density.…”

Section: A Experimental Techniquementioning

confidence: 99%

Electron density and collision frequency of microwave resonant cavity produced discharges. [Progress report]

McColl¹,

Brooks²,

Brake³

1992

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“…Different configurations have been explored for coupling microwave power to a gas, the most promising for thruster applications is the cylindrical resonant cavity design, employing either the TM 011 or TM 012 microwave mode structure. The first thruster of this kind was build in the early 1980's and it consisted of a cylindrical microwave resonant cavity at 2.45 GHz and a quartz tube, arranged concentrically [4]. He or N 2 gas flowed through the quartz tube, where the walls stabilized the microwave plasma on the centerline.…”

Section: Previous Workmentioning

confidence: 99%

Numerical simulation of microwave-sustained supersonic plasmas for application to space propulsion

Chiravalle

Miles

Choueiri

2001

39th Aerospace Sciences Meeting and Exhibit

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The concept of adding energy to an expanding supersonic flow using a microwave-sustained plasma is explored numerically by solving the complete system of both the Maxwell equations and the Navier Stokes equations for the case of an argon flow in a realistic thruster geometry. Results show that when an additional amount of power, equal to 45 % of the power deposited in the plenum, is added to the supersonic flow a toroidal plasma forms, but only a 3 % increase in specific impulse is achieved. It is concluded that future work relating to this concept should concentrate on finding ways to confine the plasma to the centerline.

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“…For the above reasons, these discharges are generally considered to be a promising plasma source for various up-to-date technologies, far beyond the scope of common plasmaassisted technologies. Among these possible applications there are rather ambitious and intriguing projects, such as installation of an artificial ionized layer in the upper atmosphere for over-the-horizon communications and radar purposes [1][2][3][4], ground-based microwave plasma spacecraft propulsion systems for near-Earth orbit cosmic flights [5][6][7], application of microwave plasmas to some urgent ecological problems [8,9] and so on.…”

Section: Introductionmentioning

confidence: 99%

Plasma structure formation in a free-localized high-pressure microwave discharge

Sinkevich

Sosnin

1996

J. Phys. D: Appl. Phys.

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The phenomenon of plasma self-organization in a free-localized high-pressure microwave discharge has been investigated on the basis of the mechanism of ionization-field (IF) instability. Linear and weakly nonlinear stages of discharge evolution have been studied. It has been shown that IF instability at the nonlinear stage, due to the interaction of the harmonics with different wavevectors, can lead to the formation of a rich spectrum of plasma structures, from simple plane plasma autowaves to various 3D spatial structures (helical filaments and three-dimensional Bernard cells).

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Microwave electrothermal thruster performance in helium gas

Cited by 42 publications

References 7 publications

Electron density and collision frequency of microwave resonant cavity produced discharges. [Progress report]

Electron density and collision frequency of microwave resonant cavity produced discharges. [Progress report]

Numerical simulation of microwave-sustained supersonic plasmas for application to space propulsion

Plasma structure formation in a free-localized high-pressure microwave discharge

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