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Igor V Adamovich - One of the best experts on this subject based on the ideXlab platform.
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dynamics of rapid localized heating in nanosecond pulse discharges for high speed flow control
Journal of Fluid Science and Technology, 2013Co-Authors: Aaron Montello, Munetake Nishihara, Walter R Lempert, David Burnette, Igor V AdamovichAbstract:Picosecond CARS spectroscopy and phased-locked schlieren imaging are used to measure time-resolved temperature and visualize Compression Waves in a diffuse filament, nanosecond pulsed discharge sustained between a pair of spherical electrodes in nitrogen and air at P=100 torr. The discharge generates stable plasma with high specific energy loading (up to ~0.5 eV/molecule), and with spatial dimensions sufficiently large to enable laser diagnostic studies. The results demonstrate that significant temperature rise, up to ∆T~200 K, occurs both in nitrogen and in air, on the time scale shorter than the acoustic time scale. The characteristic time for the rapid temperature rise in air, ~100 ns, is significantly shorter compared to that in nitrogen, ~1 µs. In air, a second significant temperature rise, up to ∆T~350 K, occurs on a time scale of ~100-500 µs. This “slow” temperature rise is almost entirely missing in nitrogen. Phase-locked schlieren images demonstrate a near cylindrical shape Compression wave formed around the discharge filament, both in nitrogen and in air. An additional, near spherical shape Compression wave is formed near the cathode, due to significant energy release in the cathode layer of the discharge. The Compression Waves, caused by rapid localized heating quantified by the present measurements, are similar to the ones produced by a surface nanosecond pulse discharge in atmospheric air used for high-speed flow control, where comparable temperature rise was detected previously.
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separation control with nanosecond pulse driven dielectric barrier discharge plasma actuators
AIAA Journal, 2012Co-Authors: Jesse Little, Munetake Nishihara, Keisuke Takashima, Igor V Adamovich, Mo SamimyAbstract:Abstract : The efficacy of dielectric barrier discharge (DBD) plasmas driven by high voltage (approximately 15 kV) repetitive nanosecond pulses approximately 100 ns FWHM) for flow separation control is investigated experimentally on an airfoil leading edge up to Re=1x106 (62 m/s). Unlike AC-DBDs, the nanosecond pulse driven DBD plasma actuator transfers very little momentum to the neutral air, but generates Compression Waves similar to localized arc filament plasma actuators. A complex pattern of quasi-planar and spherical Compression Waves is observed in still air. Measurements suggest that some of these Compression Waves are generated by discharge filaments that remain fairly reproducible pulse-to-pulse. The device performs as an active trip at high Re pre-stall angles of attack and provides perturbations that generate coherent spanwise vortices at post-stall. These coherent structures entrain freestream momentum thereby reattaching the normally separated flow to the suction surface of the airfoil. Coherent structures are identified at all tested frequencies, but values of F(subponent c, exponent +)=4-6 are most effective for control. Such devices which are believed to function through thermal effects could be an alternative to AC-DBD plasmas that rely on momentum addition.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Igor V Adamovich, Walter R Lempert, Yvette Zuzeek, Michael A ChaszeykaAbstract:The present work discusses experimental characterization of a surface Dielectric Barrier Discharge (DBD) plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The measurements have been conducted in quiescent room air. Current, voltage, instantaneous power, and coupled pulse energy in the surface DBD actuator powered by high voltage nanosecond pulses have been measured for different pulse peak voltages, pulse repetition rates, and actuator lengths. Pulse energy per unit length is controlled primarily by the pulse peak voltage and is not affected by the actuator length. The results show that the actuator can be scaled to a length of at least 1.5 m. Images of the plasma generated during the nanosecond pulse discharge development have been taken by an ICCD camera with nanosecond gate. The results show that the plasma remains fairly uniform in the initial phase of discharge development and becomes highly filamentary at a later stage. Although the negative polarity nanosecond pulse discharge generates uniform plasma at low pulse repetition rates (~100 Hz), the plasma becomes strongly filamentary as the pulse repetition rate is increased beyond ~1 kHz. Phase-locked schlieren images have been used to visualize Compression Waves generated by the repetitively pulsed plasma and to measure the Compression wave propagation speed. Density gradient in the Compression Waves generated by the nanosecond pulse discharge has been inferred from the schlieren images using calibration by a pair of wedged mirrors. The results demonstrate that Compression Waves generated by discharge filaments have higher amplitude and higher speed, compared to those produced in a diffuse discharge. Purely rotational CARS thermometry has been used to measure the temperature in a repetitive nanosecond pulse discharge filament, stabilized by using a sharp point floating electrode. The temperature rise in the filament, inferred from the CARS measurements, approximately ΔT=40 K, is significantly lower compared to the temperature rise in the filament inferred from the UV/visible emission spectroscopy measurements at the same conditions, ΔT=350 K. Comparison of the experimental density gradient in a Compression wave generated by a nanosecond pulse discharge filament with modeling calculations suggests that the temperature inferred from the emission spectroscopy is more accurate.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Walter R Lempert, Yvette Zuzeek, Igor V AdamovichAbstract:The paper discusses experimental characterization of a surface dielectric barrier discharge plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The discharge pulse energy is controlled primarily by the pulse peak voltage and scales approximately linearly with the length of the electrodes. Images of the plasma generated during the discharge pulse, taken by a nanosecond gate ICCD camera, show that the plasma remains fairly uniform in the initial phase of the discharge and becomes filamentary at a later stage. The temperature rise in the discharge, operated in both continuous mode and in burst mode, is inferred from UV/visible emission spectra. Phase-locked schlieren images are used to measure the speed of the Compression Waves generated by the nanosecond pulse discharge and the density gradient in the wave. The density gradient is inferred from the schlieren images using absolute calibration by a pair of wedged windows. The results demonstrate that discharge filaments generate Compression Waves with higher amplitude and higher speed compared with Waves produced in a diffuse discharge. The density gradient in the Compression Waves is compared with numerical modeling of propagating Compression Waves produced by short-pulse localized heating, and shows satisfactory agreement between the model and the experimental results.
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mach 5 bow shock control by a nanosecond pulse surface dielectric barrier discharge
Physics of Fluids, 2011Co-Authors: Munetake Nishihara, Keisuke Takashima, J Rich, Igor V AdamovichAbstract:Bow shock perturbations in a Mach 5 air flow, produced by low-temperature, nanosecond pulse, and surface dielectric barrier discharge (DBD), are detected by phase-locked schlieren imaging. A diffuse nanosecond pulse discharge is generated in a DBD plasma actuator on a surface of a cylinder model placed in air flow in a small scale blow-down supersonic wind tunnel. Discharge energy coupled to the actuator is 7.3–7.8 mJ/pulse. Plasma temperature inferred from nitrogen emission spectra is a few tens of degrees higher than flow stagnation temperature, T = 340 ± 30 K. Phase-locked Schlieren images are used to detect Compression Waves generated by individual nanosecond discharge pulses near the actuator surface. The Compression wave propagates upstream toward the baseline bow shock standing in front of the cylinder model. Interaction of the Compression wave and the bow shock causes its displacement in the upstream direction, increasing shock stand-off distance by up to 25%. The Compression wave speed behind the...
Keisuke Takashima - One of the best experts on this subject based on the ideXlab platform.
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separation control with nanosecond pulse driven dielectric barrier discharge plasma actuators
AIAA Journal, 2012Co-Authors: Jesse Little, Munetake Nishihara, Keisuke Takashima, Igor V Adamovich, Mo SamimyAbstract:Abstract : The efficacy of dielectric barrier discharge (DBD) plasmas driven by high voltage (approximately 15 kV) repetitive nanosecond pulses approximately 100 ns FWHM) for flow separation control is investigated experimentally on an airfoil leading edge up to Re=1x106 (62 m/s). Unlike AC-DBDs, the nanosecond pulse driven DBD plasma actuator transfers very little momentum to the neutral air, but generates Compression Waves similar to localized arc filament plasma actuators. A complex pattern of quasi-planar and spherical Compression Waves is observed in still air. Measurements suggest that some of these Compression Waves are generated by discharge filaments that remain fairly reproducible pulse-to-pulse. The device performs as an active trip at high Re pre-stall angles of attack and provides perturbations that generate coherent spanwise vortices at post-stall. These coherent structures entrain freestream momentum thereby reattaching the normally separated flow to the suction surface of the airfoil. Coherent structures are identified at all tested frequencies, but values of F(subponent c, exponent +)=4-6 are most effective for control. Such devices which are believed to function through thermal effects could be an alternative to AC-DBD plasmas that rely on momentum addition.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Walter R Lempert, Yvette Zuzeek, Igor V AdamovichAbstract:The paper discusses experimental characterization of a surface dielectric barrier discharge plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The discharge pulse energy is controlled primarily by the pulse peak voltage and scales approximately linearly with the length of the electrodes. Images of the plasma generated during the discharge pulse, taken by a nanosecond gate ICCD camera, show that the plasma remains fairly uniform in the initial phase of the discharge and becomes filamentary at a later stage. The temperature rise in the discharge, operated in both continuous mode and in burst mode, is inferred from UV/visible emission spectra. Phase-locked schlieren images are used to measure the speed of the Compression Waves generated by the nanosecond pulse discharge and the density gradient in the wave. The density gradient is inferred from the schlieren images using absolute calibration by a pair of wedged windows. The results demonstrate that discharge filaments generate Compression Waves with higher amplitude and higher speed compared with Waves produced in a diffuse discharge. The density gradient in the Compression Waves is compared with numerical modeling of propagating Compression Waves produced by short-pulse localized heating, and shows satisfactory agreement between the model and the experimental results.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Igor V Adamovich, Walter R Lempert, Yvette Zuzeek, Michael A ChaszeykaAbstract:The present work discusses experimental characterization of a surface Dielectric Barrier Discharge (DBD) plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The measurements have been conducted in quiescent room air. Current, voltage, instantaneous power, and coupled pulse energy in the surface DBD actuator powered by high voltage nanosecond pulses have been measured for different pulse peak voltages, pulse repetition rates, and actuator lengths. Pulse energy per unit length is controlled primarily by the pulse peak voltage and is not affected by the actuator length. The results show that the actuator can be scaled to a length of at least 1.5 m. Images of the plasma generated during the nanosecond pulse discharge development have been taken by an ICCD camera with nanosecond gate. The results show that the plasma remains fairly uniform in the initial phase of discharge development and becomes highly filamentary at a later stage. Although the negative polarity nanosecond pulse discharge generates uniform plasma at low pulse repetition rates (~100 Hz), the plasma becomes strongly filamentary as the pulse repetition rate is increased beyond ~1 kHz. Phase-locked schlieren images have been used to visualize Compression Waves generated by the repetitively pulsed plasma and to measure the Compression wave propagation speed. Density gradient in the Compression Waves generated by the nanosecond pulse discharge has been inferred from the schlieren images using calibration by a pair of wedged mirrors. The results demonstrate that Compression Waves generated by discharge filaments have higher amplitude and higher speed, compared to those produced in a diffuse discharge. Purely rotational CARS thermometry has been used to measure the temperature in a repetitive nanosecond pulse discharge filament, stabilized by using a sharp point floating electrode. The temperature rise in the filament, inferred from the CARS measurements, approximately ΔT=40 K, is significantly lower compared to the temperature rise in the filament inferred from the UV/visible emission spectroscopy measurements at the same conditions, ΔT=350 K. Comparison of the experimental density gradient in a Compression wave generated by a nanosecond pulse discharge filament with modeling calculations suggests that the temperature inferred from the emission spectroscopy is more accurate.
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mach 5 bow shock control by a nanosecond pulse surface dielectric barrier discharge
Physics of Fluids, 2011Co-Authors: Munetake Nishihara, Keisuke Takashima, J Rich, Igor V AdamovichAbstract:Bow shock perturbations in a Mach 5 air flow, produced by low-temperature, nanosecond pulse, and surface dielectric barrier discharge (DBD), are detected by phase-locked schlieren imaging. A diffuse nanosecond pulse discharge is generated in a DBD plasma actuator on a surface of a cylinder model placed in air flow in a small scale blow-down supersonic wind tunnel. Discharge energy coupled to the actuator is 7.3–7.8 mJ/pulse. Plasma temperature inferred from nitrogen emission spectra is a few tens of degrees higher than flow stagnation temperature, T = 340 ± 30 K. Phase-locked Schlieren images are used to detect Compression Waves generated by individual nanosecond discharge pulses near the actuator surface. The Compression wave propagates upstream toward the baseline bow shock standing in front of the cylinder model. Interaction of the Compression wave and the bow shock causes its displacement in the upstream direction, increasing shock stand-off distance by up to 25%. The Compression wave speed behind the...
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High Lift Airfoil Leading Edge Separation Control with Nanosecond Pulse Driven DBD Plasma Actuators
5th Flow Control Conference, 2010Co-Authors: Jesse Little, Munetake Nishihara, Keisuke Takashima, Igor V Adamovich, Mo SamimyAbstract:The efficacy of dielectric barrier discharge (DBD) plasmas driven by repetitive nanosecond (NS) pulses for flow separation control is investigated experimentally on an airfoil leading edge up to Re=1x10 (62 m/s). The NS pulse driven DBD plasma actuator (NSDBD hereafter) transfers very little momentum to the neutral air, but generates Compression Waves similar to localized arc filament plasma actuators. Experimental results indicate that NS-DBD plasma performs as an active trip at pre-stall angles of attack and provides high amplitude perturbations that manipulate flow instabilities and generate coherent spanwise vortices at post-stall angles. These coherent structures entrain freestream momentum thereby reattaching the normally separated flow to the suction surface of the airfoil. Such devices which are believed to function through thermal effects could result in a significant improvement over AC-DBD plasmas that rely on momentum addition which limits their performance at high speeds.
Roger A Pielke - One of the best experts on this subject based on the ideXlab platform.
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Thermally Induced Compression Waves and Gravity Waves Generated by Convective Storms
Journal of the Atmospheric Sciences, 2000Co-Authors: Melville E Nicholls, Roger A PielkeAbstract:Abstract A three-dimensional, fully compressible cloud model is used to simulate a convective storm in order to investigate the properties of Compression Waves and gravity Waves induced by latent heat release. Time series of the low-level pressure perturbations caused by the propagating Waves are examined at various distances from the storm. A Compression wave that is close to hydrostatic balance and can be considered to be a Lamb wave, which propagates in the horizontal plane, emerges from the storm. This latter property gives the wave a distinctly two-dimensional character that is clarified by comparison with a linear model of a two-dimensional thermally induced Compression wave. This has implications for its shape and results in a decay rate with distance propagated from the source of 1/(distance)1/2. The period of the Lamb wave is determined primarily by the time it takes for the storm to develop and decay. The fast-moving Lamb wave is trailed by slower-moving thermally induced gravity Waves. It is fo...
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thermal Compression Waves i total energy transfer
Quarterly Journal of the Royal Meteorological Society, 1994Co-Authors: Melville E Nicholls, Roger A PielkeAbstract:Total energy is considered a fundamental quantity that is transferred poleward by the general circulation of the atmosphere. In this study we investigate the mechanism for the upscale transfer of total energy from a localized heat source, such as a thunderstorm. Using a fully compressible numerical model it is shown that thermal Compression Waves can effectively transfer total energy at the speed of sound. It is suggested that physical interpretations of the energy cycle should take into consideration this mechanism for transferring total energy.
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thermal Compression Waves ii mass adjustment and vertical transfer of total energy
Quarterly Journal of the Royal Meteorological Society, 1994Co-Authors: Melville E Nicholls, Roger A PielkeAbstract:A fully compressible model is used to simulate the mass adjustment that occurs in response to a prescribed heat source. Results illustrate the role that thermal Compression Waves have in this process. The vertical mass transport associated with Compression Waves decreases rapidly with height. Most of the mass transport occurs in the horizontal, with the vertical structure of the disturbance similar to that of a Lamb wave. The vertical transfer of total energy in a thermally driven mixed layer is also examined. It is shown that the upward transport of total energy is accomplished by a Compression effect rather than by the exchange of warm and cold air by buoyant thermals. Model results are analysed to determine budgets of total energy, mass and entropy. It is demonstrated that buoyant thermals are predominantly responsible for a transfer of entropy, rather than total energy. In the light of these results the notion of ‘heat transport’ in a fluid is discussed.
Walter R Lempert - One of the best experts on this subject based on the ideXlab platform.
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dynamics of rapid localized heating in nanosecond pulse discharges for high speed flow control
Journal of Fluid Science and Technology, 2013Co-Authors: Aaron Montello, Munetake Nishihara, Walter R Lempert, David Burnette, Igor V AdamovichAbstract:Picosecond CARS spectroscopy and phased-locked schlieren imaging are used to measure time-resolved temperature and visualize Compression Waves in a diffuse filament, nanosecond pulsed discharge sustained between a pair of spherical electrodes in nitrogen and air at P=100 torr. The discharge generates stable plasma with high specific energy loading (up to ~0.5 eV/molecule), and with spatial dimensions sufficiently large to enable laser diagnostic studies. The results demonstrate that significant temperature rise, up to ∆T~200 K, occurs both in nitrogen and in air, on the time scale shorter than the acoustic time scale. The characteristic time for the rapid temperature rise in air, ~100 ns, is significantly shorter compared to that in nitrogen, ~1 µs. In air, a second significant temperature rise, up to ∆T~350 K, occurs on a time scale of ~100-500 µs. This “slow” temperature rise is almost entirely missing in nitrogen. Phase-locked schlieren images demonstrate a near cylindrical shape Compression wave formed around the discharge filament, both in nitrogen and in air. An additional, near spherical shape Compression wave is formed near the cathode, due to significant energy release in the cathode layer of the discharge. The Compression Waves, caused by rapid localized heating quantified by the present measurements, are similar to the ones produced by a surface nanosecond pulse discharge in atmospheric air used for high-speed flow control, where comparable temperature rise was detected previously.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Igor V Adamovich, Walter R Lempert, Yvette Zuzeek, Michael A ChaszeykaAbstract:The present work discusses experimental characterization of a surface Dielectric Barrier Discharge (DBD) plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The measurements have been conducted in quiescent room air. Current, voltage, instantaneous power, and coupled pulse energy in the surface DBD actuator powered by high voltage nanosecond pulses have been measured for different pulse peak voltages, pulse repetition rates, and actuator lengths. Pulse energy per unit length is controlled primarily by the pulse peak voltage and is not affected by the actuator length. The results show that the actuator can be scaled to a length of at least 1.5 m. Images of the plasma generated during the nanosecond pulse discharge development have been taken by an ICCD camera with nanosecond gate. The results show that the plasma remains fairly uniform in the initial phase of discharge development and becomes highly filamentary at a later stage. Although the negative polarity nanosecond pulse discharge generates uniform plasma at low pulse repetition rates (~100 Hz), the plasma becomes strongly filamentary as the pulse repetition rate is increased beyond ~1 kHz. Phase-locked schlieren images have been used to visualize Compression Waves generated by the repetitively pulsed plasma and to measure the Compression wave propagation speed. Density gradient in the Compression Waves generated by the nanosecond pulse discharge has been inferred from the schlieren images using calibration by a pair of wedged mirrors. The results demonstrate that Compression Waves generated by discharge filaments have higher amplitude and higher speed, compared to those produced in a diffuse discharge. Purely rotational CARS thermometry has been used to measure the temperature in a repetitive nanosecond pulse discharge filament, stabilized by using a sharp point floating electrode. The temperature rise in the filament, inferred from the CARS measurements, approximately ΔT=40 K, is significantly lower compared to the temperature rise in the filament inferred from the UV/visible emission spectroscopy measurements at the same conditions, ΔT=350 K. Comparison of the experimental density gradient in a Compression wave generated by a nanosecond pulse discharge filament with modeling calculations suggests that the temperature inferred from the emission spectroscopy is more accurate.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Walter R Lempert, Yvette Zuzeek, Igor V AdamovichAbstract:The paper discusses experimental characterization of a surface dielectric barrier discharge plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The discharge pulse energy is controlled primarily by the pulse peak voltage and scales approximately linearly with the length of the electrodes. Images of the plasma generated during the discharge pulse, taken by a nanosecond gate ICCD camera, show that the plasma remains fairly uniform in the initial phase of the discharge and becomes filamentary at a later stage. The temperature rise in the discharge, operated in both continuous mode and in burst mode, is inferred from UV/visible emission spectra. Phase-locked schlieren images are used to measure the speed of the Compression Waves generated by the nanosecond pulse discharge and the density gradient in the wave. The density gradient is inferred from the schlieren images using absolute calibration by a pair of wedged windows. The results demonstrate that discharge filaments generate Compression Waves with higher amplitude and higher speed compared with Waves produced in a diffuse discharge. The density gradient in the Compression Waves is compared with numerical modeling of propagating Compression Waves produced by short-pulse localized heating, and shows satisfactory agreement between the model and the experimental results.
Yvette Zuzeek - One of the best experts on this subject based on the ideXlab platform.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Igor V Adamovich, Walter R Lempert, Yvette Zuzeek, Michael A ChaszeykaAbstract:The present work discusses experimental characterization of a surface Dielectric Barrier Discharge (DBD) plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The measurements have been conducted in quiescent room air. Current, voltage, instantaneous power, and coupled pulse energy in the surface DBD actuator powered by high voltage nanosecond pulses have been measured for different pulse peak voltages, pulse repetition rates, and actuator lengths. Pulse energy per unit length is controlled primarily by the pulse peak voltage and is not affected by the actuator length. The results show that the actuator can be scaled to a length of at least 1.5 m. Images of the plasma generated during the nanosecond pulse discharge development have been taken by an ICCD camera with nanosecond gate. The results show that the plasma remains fairly uniform in the initial phase of discharge development and becomes highly filamentary at a later stage. Although the negative polarity nanosecond pulse discharge generates uniform plasma at low pulse repetition rates (~100 Hz), the plasma becomes strongly filamentary as the pulse repetition rate is increased beyond ~1 kHz. Phase-locked schlieren images have been used to visualize Compression Waves generated by the repetitively pulsed plasma and to measure the Compression wave propagation speed. Density gradient in the Compression Waves generated by the nanosecond pulse discharge has been inferred from the schlieren images using calibration by a pair of wedged mirrors. The results demonstrate that Compression Waves generated by discharge filaments have higher amplitude and higher speed, compared to those produced in a diffuse discharge. Purely rotational CARS thermometry has been used to measure the temperature in a repetitive nanosecond pulse discharge filament, stabilized by using a sharp point floating electrode. The temperature rise in the filament, inferred from the CARS measurements, approximately ΔT=40 K, is significantly lower compared to the temperature rise in the filament inferred from the UV/visible emission spectroscopy measurements at the same conditions, ΔT=350 K. Comparison of the experimental density gradient in a Compression wave generated by a nanosecond pulse discharge filament with modeling calculations suggests that the temperature inferred from the emission spectroscopy is more accurate.
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characterization of a surface dielectric barrier discharge plasma sustained by repetitive nanosecond pulses
Plasma Sources Science and Technology, 2011Co-Authors: Keisuke Takashima, Walter R Lempert, Yvette Zuzeek, Igor V AdamovichAbstract:The paper discusses experimental characterization of a surface dielectric barrier discharge plasma sustained by repetitive, high-voltage, nanosecond duration pulses. The discharge pulse energy is controlled primarily by the pulse peak voltage and scales approximately linearly with the length of the electrodes. Images of the plasma generated during the discharge pulse, taken by a nanosecond gate ICCD camera, show that the plasma remains fairly uniform in the initial phase of the discharge and becomes filamentary at a later stage. The temperature rise in the discharge, operated in both continuous mode and in burst mode, is inferred from UV/visible emission spectra. Phase-locked schlieren images are used to measure the speed of the Compression Waves generated by the nanosecond pulse discharge and the density gradient in the wave. The density gradient is inferred from the schlieren images using absolute calibration by a pair of wedged windows. The results demonstrate that discharge filaments generate Compression Waves with higher amplitude and higher speed compared with Waves produced in a diffuse discharge. The density gradient in the Compression Waves is compared with numerical modeling of propagating Compression Waves produced by short-pulse localized heating, and shows satisfactory agreement between the model and the experimental results.