The isentropic exponent in plasmas

Burm, Ktal Karel; Goedheer, W. J.; Schram, DC Daan

doi:10.1063/1.873535

Cited by 47 publications

(34 citation statements)

References 3 publications

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“…An analysis of how ␥ depends on the ionization degree and temperature can be found in Ref. 10. It should be noted that to create a plasma, heat is supplied to ionize.…”

Section: Cϭͱ␥rt ͑4a͒mentioning

confidence: 99%

“…The isentropic exponent, which equals the ratio of the heat capacities at constant pressure, c p , and at constant volume, c v , is lower in a plasma than in a gas. 10 A plasma is never isentropic, which is due to inelastic collisions that ionize the plasma, due to viscosity, and due to Ohmic heating of the plasma. This nonisentropic behavior requires a more accurate specification of the plasma temperature and the isentropic exponent.…”

Section: Cϭͱ␥rt ͑4a͒mentioning

confidence: 99%

“…The Mach number, M, is defined [10][11][12][13][14][15][16] as the ratio of the local velocity, w, and the local speed of sound, c…”

Section: The Plasma Mach Numbermentioning

confidence: 99%

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Mach numbers for gases and plasmas in a convergent-divergent cascaded arc

1999

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For a plasma, flowing through a cascaded arc channel with a varying cross-section, and flowing from a subsonic to a supersonic state, the sonic condition moves downstream and the plasma Mach number at the smallest cross section is less than one, although in case of a transonic isentropic gas flow the sonic condition is found at the smallest cross section. This shift in sonic condition is due to the lack of isentropic behavior of the plasma flow. Sources causing the anisentropy are viscosity, heat and ionization, of which ionization is vital for a plasma. It is found that the plasma Mach number is always lower than the corresponding gas Mach number. A quasi one-dimensional analysis and simulations with a two-dimensional plasma model, which support the analysis, are presented.

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“…An analysis of how ␥ depends on the ionization degree and temperature can be found in Ref. 10. It should be noted that to create a plasma, heat is supplied to ionize.…”

Section: Cϭͱ␥rt ͑4a͒mentioning

confidence: 99%

Section: Cϭͱ␥rt ͑4a͒mentioning

confidence: 99%

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Mach numbers for gases and plasmas in a convergent-divergent cascaded arc

1999

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“…Quantities have been normalized as follows: velocities to √ T 0 /m i (with T 0 a reference electron temperature and m i the ion mass), the electrostatic potential to T 0 /e (with e the elementary charge), density to a reference density n 0 , lengths to a characteristic length R, and pressure to n 0 T 0 . In general, the value of the polytropic index γ depends on the degree of ionization of the plasma [23]. For instance, [7] have reported experimental results for thrusters, with γ lower than 5/3, and [24] have used the value 1.3 for their PIC simulations.…”

Section: Mathematical Modelmentioning

confidence: 99%

Approximate semi-analytical solutions for the steady-state expansion of a contactor plasma

Camporeale¹,

Hogan²,

MacDonald³

2015

Plasma Sources Sci. Technol.

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We study the steady-state expansion of a collisionless, electrostatic, quasi-neutral plasma plume into vacuum, with a fluid model. We analyze approximate semi-analytical solutions, that can be used in lieu of much more expensive numerical solutions. In particular, we focus on the earlier studies presented in Parks and Katz (1979 (Pasadena, CA)). By calculating the error with respect to the numerical solution, we can judge the range of validity for each solution. Moreover, we introduce a generalization of earlier models that has a wider range of applicability, in terms of plasma injection profiles. We conclude by showing a straightforward way to extend the discussed solutions to the case of a plasma plume injected with non-null azimuthal velocity.

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“…The designed Mach number for argon flows is about 10, where for simplicity the specific heat ratio is fixed. 18,19) As a beam source, a continuous wave carbon dioxide laser (YB-L200B7T4, Matsushita Electric Industrial Co., Ltd.) was used. The wavelength is 10.6 m.…”

Section: Experimental Setup Of Lsp Generatormentioning

confidence: 99%

Operation Characteristics of Laser Driven Plasma Wind Tunnel

Matsui

Shinmi

Ueno

et al. 2009

Trans. JSASS Space Tech. Japan

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A laser driven plasma wind tunnel using a 2 kW class continuous wave laser was developed as a high speed and high density atomic oxygen generator. Firstly, its operation conditions were examined. Using argon and oxygen as working gases, laser sustained plasma (LSP) was successfully produced in the plenum pressure range from 0.30 MPa to 0.95 MPa, and then the LSP was expanded to the vacuum chamber through the convergent-divergent nozzle. Next, plume characteristics were evaluated by Pitot probe and laser absorption spectroscopy using an absorption line of ArI 772.38 nm. As a result, the Mach number and the specific enthalpy around the center were 5.0 to 6.5 and 3.0 MJ/kg to 5.2 MJ/kg, respectively. The maximum flux density of atomic oxygen was estimated as 2.2×10 21 cm -2 s -1 .

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The isentropic exponent in plasmas

Cited by 47 publications

References 3 publications

Mach numbers for gases and plasmas in a convergent-divergent cascaded arc

Mach numbers for gases and plasmas in a convergent-divergent cascaded arc

Approximate semi-analytical solutions for the steady-state expansion of a contactor plasma

Operation Characteristics of Laser Driven Plasma Wind Tunnel

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