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

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

doi:10.1063/1.873536

Cited by 13 publications

(29 citation statements)

References 12 publications

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“…A second one is the relevance of ionization and collisional process in the real plasma plume, also neglected in the model. Incidentally, collisions would also justify that the sonic point is here placed inside the divergent nozzle and not at a MN throat [39,40]. And finally, discrepancies should not be attributed exclusively to the theory.…”

Section: Resultsmentioning

confidence: 98%

Plasma beam characterization along the magnetic nozzle of an ECR thruster

Correyero¹,

Jarrige²,

Packan³

et al. 2019

Plasma Sources Sci. Technol.

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Experimental characterization of plasma properties along the magnetic nozzle of an Electron Cyclotron Resonance thruster is presented here. A permanent magnet prototype and a solenoid prototype are tested, whose main difference relies on the magnetic field strength and topology. A cylindrical Langmuir probe is used to measure plasma potential, plasma density and electron temperature. In the permanent magnet thruster setup , a Laser Induced Fluorescence diagnostics is performed simultaneously with the Langmuir probe to measure the mean ion kinetic energy, and a Faraday gridded probe to characterize the angular plasma beam. An effective electron cooling rate has been identified, as well as the dependence of the total plasma potential drop with the mass flow rate. Results are compared with a supersonic collisionless fluid-kinetic 1D model where electron dynamics account for magnetic mirror effects and potential barriers, while ions are treated as a fluid cold species. The comparison allows to estimate the sonic transition of the plasma flow.

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Section: Resultsmentioning

confidence: 98%

Plasma beam characterization along the magnetic nozzle of an ECR thruster

Correyero¹,

Jarrige²,

Packan³

et al. 2019

Plasma Sources Sci. Technol.

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“…ionization), is lower than the adiabatic value. In particular, as a consequence of the different behaviour of constant pressure and constant volume specific heats, it is found that their ratio is constant also for plasmas [59], provided the degree of ionization lies between 5% and 80%. For an atmospheric plasma, whose temperatures are of the order of the eV, γ=1.16 instead of the γ=1.4 valid for ordinary gases.…”

Section: Sound Velocitymentioning

confidence: 98%

“…In [36] and more recently in Burm et al [59], it is stated that the Mach number of a plasma is always lower than the corresponding value for the gas. This is a consequence of the value of the isentropic exponent in plasma that, due to additional degrees of freedom with respect to the ordinary gas (e.g.…”

Section: Sound Velocitymentioning

confidence: 99%

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A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas

Fanara

Richardson

2001

J. Phys. D: Appl. Phys.

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The 'high-pressure' atmospheric (TIG) arc plasma is studied by means of a multi-Langmuir probe system. In order to determine the appropriate regime of operation, definitions of the plasma parameters for the description of the argon arc are considered and evaluations are presented. A description of the probe basic techniques is followed by an in-depth discussion of the different regimes of probe operation. The emphasis is put on atmospheric and flowing (arc) regimes. Probe sheath theories are compared and "Nonidealities" like cooling due to plasma-probe motion and probe emission mechanisms are then described.The extensive literature review reveals that the existing probe theories are inappropriate for a use in the TIG arc, because of 'high' pressure (atmospheric), broad range of ionization across the arc, flowing conditions, and ultimately, to the uncertainty about onset of Local Thermodynamical Equilibrium. The Langmuir probe system is built to operate in floating and biased conditions. The present work represents the first extensive investigation of electrostatic probes in arcs where the experimental difficulties and the primary observed quantities are presented in great detail. Analysis methodologies are introduced and experimental results are presented towards a unified picture of the resulting arc structure by comparison with data from emission spectroscopy. Results from different measurements are presented and comparison is made with data on TIG arcs present in literature. Probe obtained temperatures are lower than the values obtained from emission spectroscopy and this 'cooling' is attributed to electron-ion recombination. However, it is believed that probes can access temperatures regions not attainable by emission spectroscopy. Only axial electric potential and electric field are obtained because of the equipotential-probe requirement. Estimations of the sheath voltage and extension are obtained and a qualitative picture of the ion and electron current densities within the arc is given.on floating and plasma potentials and estimates of the sheath voltage are made, which are then compared with the results of Chapter 4. Chapter 13 deals with further 'electrical' parameters (current densities, electric field and electrical conductivity). In Chapter 14 several experimental results are presented together in order to gain a unified picture of the resulting arc structure and some observations about possible conduction structures within arcs are made. Finally Chapter 15, after a summary of the whole work, reports the conclusions obtained and suggests further investigations.

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“…The lower isentropic exponent upstream the flat plate has a direct influence on the interaction between the supersonic gas flow and the flat plate and, then, on the shock wave. A modification of the isentropic exponent leads to a change in the velocity of the flow and the Mach number [29,51]. To evaluate this effect we used the Barré de Saint-Venant equation to estimate the flow velocity upstream of the flat plate when the plasma actuator is switched on.…”

Section: Analysis Of Ionization Degree In the Shock Wave Angle Increasementioning

confidence: 99%

Experimental investigation of the properties of a glow discharge used as plasma actuator applied to rarefied supersonic flow control around a flat plate

Joussot

Lago

2016

IEEE Trans. Dielect. Electr. Insul.

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This paper describes experimental investigations focused on the glow discharge created by a plasma actuator and used to shock wave modification over a flat plate in a Mach 2 air flow. The model is equipped with a plasma actuator composed of two electrodes. A weakly ionized plasma is created above the plate by generating a glow discharge with a negative dc potential applied to the upstream electrode. ICCD images of the discharge without and with the Mach 2 flow show the influence of the flow field on the discharge morphology. In addition, ICCD images of the modified flow revealed that when the discharge is ignited, the shock wave angle increased with the applied voltage. Thermal measurements of the flat plate surface carried out with an IR camera showed that the spatial temperature distribution is not uniform along the plate and its maximum, near the leading edge, increases with the applied voltage. Previous results showed that surface heating is responsible for roughly 50% of the shock wave angle increase, meaning that purely plasma effects must also be considered to fully explain the flow modifications observed. The focus of this paper is the study of the properties of the glow discharge to better understand the interaction between the supersonic flow and the purely plasma effects which are responsible of flow field modifications, in particular ionization degree and thermal disequilibrium upstream the model. U 1 = 511 m.s -1 M 1 = 2  1 = 0.375 mm q m = 3.34e -3 kg.s -1 2.2 FLAT PLATE AND PLASMA ACTUATOR A schematic view of the experimental arrangement is presented on Figure 2. The model under investigation is a flat plate mounted in the test section, 174 mm downstream the nozzle exit. The flat plate is made of quartz with 100 mm long, 80 mm wide, and 4 mm thick and presents a sharp 672 R. Joussot and V. Lago: Experimental Investigation of the Properties of a Glow Discharge used as Plasma Actuator

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

Cited by 13 publications

References 12 publications

Plasma beam characterization along the magnetic nozzle of an ECR thruster

Plasma beam characterization along the magnetic nozzle of an ECR thruster

A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas

Experimental investigation of the properties of a glow discharge used as plasma actuator applied to rarefied supersonic flow control around a flat plate

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