Visible light emission measurements from a dense electrothermal launcher plasma

Hankins, O.E.; Bourham, Mohamed; Earnhart, J.; Gilligan, J.G.

doi:10.1109/20.195745

Cited by 32 publications

(16 citation statements)

References 7 publications

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“…Taylor 11,12 performed radiative heat flux measurements on plasmas emerging from a long capillary into stagnant air at 1 atm. The experimental configuration was similar to the one used by Hankins and Mann 13 and Hankins et al 14,15 A polyethylene capillary of about 175 mm in length was employed, coupled with very large input energy levels of 40 kJ. The copper initiation wire was 1 mm in diameter, which is significant.…”

Section: Introductionmentioning

confidence: 99%

Transient Radiative Heat Transfer from a Plasma Produced by a Capillary Discharge

Das

Thynell

et al. 2005

Journal of Thermophysics and Heat Transfer

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The objective of this work is to develop a better understanding of the transient behavior of radiative heat transfer from a plasma. The plasma generation occurred within a 3.2-mm-diam and 26-mm-long polyethylene capillary. Because of its high temperature and high pressure, the plasma evolved from the capillary into an ambient air environment as an underexpanded supersonic jet that interacted with a stagnation plate. Various diagnostic techniques were used. They include heat flux and pressure gauges mounted on the stagnation plate, heat flux gauges and silicon photodiodes mounted below the plasma jet, as well as current transducers interfaced with the electrical circuit. The heat flux gauges were manufactured via sputtering and calibrated using a standard convection oven. A fused-silica window, placed about 1 mm above the gauges, ensured that only the radiative heat flux transmitted by the window was deduced. The row of heat flux gauges mounted below the plasma provided an assessment of the fraction of the radiative heat flux transmitted by the fused-silica window. The results show that the peak of emitted radiant flux occurs immediately after the peak of the discharge of electrical energy, which usually occurred a relatively long time prior to arrival of the precursor shock on the stagnation plate. Nomenclature= axial coordinate, m α = thermal diffusivity, m 2 /s β = temperature coefficient of resistivity, 1/K ρ = density, kg/m 3

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Section: Introductionmentioning

confidence: 99%

Transient Radiative Heat Transfer from a Plasma Produced by a Capillary Discharge

Das

Thynell

et al. 2005

Journal of Thermophysics and Heat Transfer

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“…The kinetic plasma temperature is often measured at the torch exit channel via optical emission spectroscopy while thermal temperature distribution may be measured with specially coated thermocouples or via infrared thermometry [7,8]. The assumption of local thermodynamic equilibrium is usually valid for thermal plasma torches, similarly for electrothermal plasma sources [7,8,12,13]. Temperatures measured in argon gas plasma jets from a 100 kW DC plasma torch have been on the order of ~11,200 K [7], while the temperatures measured from a pulsed electrothermal plasma source range from 8,800 to 14,000 K [12,13].…”

Section: Introductionmentioning

confidence: 99%

“…The assumption of local thermodynamic equilibrium is usually valid for thermal plasma torches, similarly for electrothermal plasma sources [7,8,12,13]. Temperatures measured in argon gas plasma jets from a 100 kW DC plasma torch have been on the order of ~11,200 K [7], while the temperatures measured from a pulsed electrothermal plasma source range from 8,800 to 14,000 K [12,13]. Torres et al working on high-pressure hydrogen microwave plasma torches reported temperatures in the range of 9,500 to 10,700 K measured via optical emission spectroscopy and analyzed by three different methods [8].…”

Section: Introductionmentioning

confidence: 99%

Modeling and analysis of a dual channel plasma torch for industrial, space, and launch applications

Zielinski¹,

Fair²,

Winfrey

et al. 2014

2014 17th International Symposium on Electromagnetic Launch Technology

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Dual-channel thermal plasma torches can operate with air, argon, or combustible gases to produce high temperature plasma flows. This plasma torch can be used in various important applications such as metal industry recycling, surface coating and hardening, space operations using controlled thrust, and macroparticle acceleration based on the electrothermal nature of thermal torches and electrical-to-thermal energy conversion. Power for this torch is supplied from the electric mains and the voltage is stepped up to 6 kV. However, the torch can also operate in DC or in pulsed mode. The electrical operation is characterized by the VoltAmpere relationship to determine the power rating of the torch and diagnose the dynamic behavior of the plasma. Experiments on the torch using air and argon have shown plasma temperatures of 1 eV and 0.5 eV, respectively, with plasma number densities in the range of 10 24 -10 25 /m 3 , indicating a dense plasma regime with the plasma tending to be weakly nonideal. Plasma kinetic temperature and electron number density were obtained from optical emission spectroscopy using the relative line method as the plasma is near local thermodynamic equilibrium (LTE) condition. The plasma temperature is at a maximum for low flow rates and decreases for increased flow rates. The torch modeling was conducted using an electrothermal plasma code to simulate and predict the parameters for pulsed mode operation. Simulation was conducted on a single channel as the dual torch is symmetric. Code results for extended pulse lengths show a plasma temperature between 0.6 eV and 0.8 eV for nitrogen, oxygen and helium, which are in good correlation with plasma temperatures obtained from optical emission spectra and measured plasma resistivity. A set of computational experiments using short pulses at higher discharge currents have shown temperatures in the range of 2.0-2.5 eV for nitrogen and helium.

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“…The assumption of local thermodynamic equilibrium (LTE) is usually valid for thermal plasma torches, similarly for electrothermal plasma sources [7], [8], [12], [13]. Temperature measured in argon gas plasma jet from a 100-kW dc plasma torch was ∼11 200 K [7], while that from a pulsed electrothermal plasma source ranged from 8800 to 14 000 K [12], [13].…”

mentioning

confidence: 99%

“…Temperature measured in argon gas plasma jet from a 100-kW dc plasma torch was ∼11 200 K [7], while that from a pulsed electrothermal plasma source ranged from 8800 to 14 000 K [12], [13]. The work of Torres et al [8] on high-pressure hydrogen microwave plasma torch reported temperatures in the range of 9500-10 700 K measured via optical emission spectroscopy and analyzed by three different methods, which is consistent with typical plasma torches and electrothermal plasma sources.…”

mentioning

confidence: 99%

Modeling and Analysis of a Dual-Channel Plasma Torch in Pulsed Mode Operation for Industrial, Space, and Launch Applications

Zielinski¹,

Fair²,

Winfrey

et al. 2015

IEEE Trans. Plasma Sci.

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Dual-channel thermal plasma torch can operate with air, argon, or combustible gases to produce hightemperature plasma flow. This plasma torch can be used in various important applications such as metal industry recycling, surface coating and hardening, space operations using controlled thrust, and macroparticle acceleration based on the electrothermal nature of thermal torches and electrical-to-thermal energy conversion. Power for this torch is supplied from the electric mains and the voltage is stepped up to 6 kV. However, the torch can also operate on dc or pulsed mode. The electrical operation is characterized by the voltampere relationship to determine the power rating of the torch as well as diagnosing the dynamic behavior of the plasma. Experiments on the torch using air and argon have shown plasma temperatures in the range of 0.4-0.6 eV with plasma number density in the range of 10 24 -10 25 /m 3 , indicating a dense plasma regime with the plasma tends to be weakly nonideal. Plasma kinetic temperature and electron number density were obtained from optical emission spectroscopy using the relative line method as the plasma is near local thermodynamic equilibrium condition. Plasma temperature has its peak for low flow rates and decreases for increased flow rates. The torch modeling was conducted using an electrothermal plasma code to simulate and predict the parameters for pulsed mode operation. Simulation was conducted on a single channel as the dual torch is symmetric. Code results for extended pulselength show a plasma temperature between 0.6 and 0.8 eV for nitrogen, oxygen, and helium; which are in good correlation with plasma temperatures obtained from optical emission spectra and measured plasma resistivity. A set of computational experiments using short pulses at higher discharge currents has shown temperature in the range of 2.0-2.5 eV for nitrogen and helium.

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Visible light emission measurements from a dense electrothermal launcher plasma

Cited by 32 publications

References 7 publications

Transient Radiative Heat Transfer from a Plasma Produced by a Capillary Discharge

Transient Radiative Heat Transfer from a Plasma Produced by a Capillary Discharge

Modeling and analysis of a dual channel plasma torch for industrial, space, and launch applications

Modeling and Analysis of a Dual-Channel Plasma Torch in Pulsed Mode Operation for Industrial, Space, and Launch Applications

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