The Experts below are selected from a list of 28611 Experts worldwide ranked by ideXlab platform
Richard B Miles - One of the best experts on this subject based on the ideXlab platform.
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown ...
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species independent femtosecond localized Electric Field Measurement
Physical review applied, 2017Co-Authors: Arthur Dogariu, Benjamin M Goldberg, Sean Obyrne, Richard B MilesAbstract:An Electric Field aligns charges of individual atoms or molecules to be parallel to the Field, allowing second-harmonic generation from a passing laser beam. The harmonic can be used to measure local Electric Field, for any gaseous species, with high spatial and temporal resolution. This capability opens possibilities for studying Field-driven nonequilibrium phenomena, local Field-enhanced processes, aerodynamic flow control, skin treatment, air purification, combustion, ignition, surface chemistry, and many other topics in physics, engineering, and medicine.
Benjamin M Goldberg - One of the best experts on this subject based on the ideXlab platform.
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Electric Field vector Measurements via nanosecond Electric Field induced second harmonic generation
Optics Letters, 2020Co-Authors: Tat Loon Chng, Benjamin M Goldberg, Maya Naphade, Igor V Adamovich, Svetlana StarikovskaiaAbstract:Electric-Field-induced second-harmonic generation, or E-FISH, has received renewed interest as a nonintrusive tool for probing Electric Fields in gas discharges and plasmas using ultrashort laser pulses. An important contribution of this work lies in establishing that the E-FISH method works effectively in the nanosecond regime, yielding Field sensitivities of about a kV/cm at atmospheric pressure from a 16 ns pulse. This is expected to broaden its applicability within the plasma community, given the wider access to conventional nanosecond laser sources. A Pockels-cell-based pulse-slicing scheme, which may be readily integrated with such nanosecond laser systems, is shown to be a complementary and cost-effective option for improving the time resolution of the Electric Field Measurement. Using this scheme, a time resolution of ∼3 ns is achieved, without any detriment to the signal sensitivity. This could prove invaluable for nonequilibrium plasma applications, where time resolution of a few nanoseconds or less is often critical. Finally, we take advantage of the Field vector sensitivity of the E-FISH signal to demonstrate simultaneous Measurements of both the horizontal and vertical components of the Electric Field.
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown ...
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.
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species independent femtosecond localized Electric Field Measurement
Physical review applied, 2017Co-Authors: Arthur Dogariu, Benjamin M Goldberg, Sean Obyrne, Richard B MilesAbstract:An Electric Field aligns charges of individual atoms or molecules to be parallel to the Field, allowing second-harmonic generation from a passing laser beam. The harmonic can be used to measure local Electric Field, for any gaseous species, with high spatial and temporal resolution. This capability opens possibilities for studying Field-driven nonequilibrium phenomena, local Field-enhanced processes, aerodynamic flow control, skin treatment, air purification, combustion, ignition, surface chemistry, and many other topics in physics, engineering, and medicine.
R C Myers - One of the best experts on this subject based on the ideXlab platform.
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local Electric Field Measurement in gan diodes by exciton franz keldysh photocurrent spectroscopy
Applied Physics Letters, 2020Co-Authors: Darpan Verma, Mohsinur Rahman Adnan, Mohammad Wahidur Rahman, Siddharth Rajan, R C MyersAbstract:The eXciton Franz–Keldysh (XFK) effect is observed in GaN p–n junction diodes via the spectral variation of photocurrent responsivity data that redshift and broaden with increasing reverse bias. Photocurrent spectra are quantitatively fit over a broad photon energy range to an XFK model using only a single fit parameter that determines the line shape and the local bias ( V l), uniquely determining the local Electric Field maximum and depletion widths. As expected, the spectrally determined values of V l vary linearly with the applied bias ( V) and reveal a large reduction in the local Electric Field due to electrostatic non-uniformity. The built-in bias ( V b i) is estimated by extrapolating V l at V = 0, which, when compared with independent C-V Measurements, indicates an overall ±0.31 V accuracy of V l. This demonstrates sub-bandgap photocurrent spectroscopy as a local probe of Electric Field in wide bandgap diodes that can be used to map out regions of device breakdown (hot spots) for improving electrostatic design of high-voltage devices.
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local Electric Field Measurement in gan diodes by exciton franz keldysh photocurrent spectroscopy
arXiv: Applied Physics, 2020Co-Authors: Darpan Verma, Mohsinur Rahman Adnan, Mohammad Wahidur Rahman, Siddharth Rajan, R C MyersAbstract:The eXciton Franz-Keldysh (XFK) effect is observed in GaN p-n junction diodes via the spectral variation of photocurrent responsivity data that redshift and broaden with increasing reverse bias. Photocurrent spectra are quantitatively fit over a broad photon energy range to an XFK model using only a single fit parameter that determines the lineshape, the local bias ($V_{l}$), uniquely determining the local Electric Field maximum and depletion widths. As expected, the spectrally determined values of $V_{l}$ vary linearly with the applied bias ($V$) and reveal a large reduction in the local Electric Field due to electrostatic non-uniformity. The built-in bias ($V_{bi}$) is estimated by extrapolating $V_{l}$ at $V=0$, which compared with independent C-V Measurements indicates an overall $\pm$0.31 V accuracy of $V_{l}$. This demonstrates sub-bandgap photocurrent spectroscopy as a local probe of Electric Field in wide bandgap diodes that can be used to map out regions of device breakdown (hot spots) for improving electrostatic design of high voltage devices.
Tat Loon Chng - One of the best experts on this subject based on the ideXlab platform.
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Electric Field vector Measurements via nanosecond Electric Field induced second harmonic generation
Optics Letters, 2020Co-Authors: Tat Loon Chng, Benjamin M Goldberg, Maya Naphade, Igor V Adamovich, Svetlana StarikovskaiaAbstract:Electric-Field-induced second-harmonic generation, or E-FISH, has received renewed interest as a nonintrusive tool for probing Electric Fields in gas discharges and plasmas using ultrashort laser pulses. An important contribution of this work lies in establishing that the E-FISH method works effectively in the nanosecond regime, yielding Field sensitivities of about a kV/cm at atmospheric pressure from a 16 ns pulse. This is expected to broaden its applicability within the plasma community, given the wider access to conventional nanosecond laser sources. A Pockels-cell-based pulse-slicing scheme, which may be readily integrated with such nanosecond laser systems, is shown to be a complementary and cost-effective option for improving the time resolution of the Electric Field Measurement. Using this scheme, a time resolution of ∼3 ns is achieved, without any detriment to the signal sensitivity. This could prove invaluable for nonequilibrium plasma applications, where time resolution of a few nanoseconds or less is often critical. Finally, we take advantage of the Field vector sensitivity of the E-FISH signal to demonstrate simultaneous Measurements of both the horizontal and vertical components of the Electric Field.
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown ...
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Electric Field Measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond Electric Field induced second harmonic generation
Applied Physics Letters, 2018Co-Authors: Benjamin M Goldberg, Arthur Dogariu, Richard B Miles, Tat Loon ChngAbstract:We present an optical Electric Field Measurement method for use in high pressure plasma discharges. The method is based upon the Field induced second harmonic generation technique and can be used for localized Electric Field Measurements with sub-nanosecond resolution in any gaseous species. When an external Electric Field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the Electric Field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the Field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the Electric Field is strong enough to exceed the breakdown threshold, the measured Field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.
Darpan Verma - One of the best experts on this subject based on the ideXlab platform.
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local Electric Field Measurement in gan diodes by exciton franz keldysh photocurrent spectroscopy
Applied Physics Letters, 2020Co-Authors: Darpan Verma, Mohsinur Rahman Adnan, Mohammad Wahidur Rahman, Siddharth Rajan, R C MyersAbstract:The eXciton Franz–Keldysh (XFK) effect is observed in GaN p–n junction diodes via the spectral variation of photocurrent responsivity data that redshift and broaden with increasing reverse bias. Photocurrent spectra are quantitatively fit over a broad photon energy range to an XFK model using only a single fit parameter that determines the line shape and the local bias ( V l), uniquely determining the local Electric Field maximum and depletion widths. As expected, the spectrally determined values of V l vary linearly with the applied bias ( V) and reveal a large reduction in the local Electric Field due to electrostatic non-uniformity. The built-in bias ( V b i) is estimated by extrapolating V l at V = 0, which, when compared with independent C-V Measurements, indicates an overall ±0.31 V accuracy of V l. This demonstrates sub-bandgap photocurrent spectroscopy as a local probe of Electric Field in wide bandgap diodes that can be used to map out regions of device breakdown (hot spots) for improving electrostatic design of high-voltage devices.
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local Electric Field Measurement in gan diodes by exciton franz keldysh photocurrent spectroscopy
arXiv: Applied Physics, 2020Co-Authors: Darpan Verma, Mohsinur Rahman Adnan, Mohammad Wahidur Rahman, Siddharth Rajan, R C MyersAbstract:The eXciton Franz-Keldysh (XFK) effect is observed in GaN p-n junction diodes via the spectral variation of photocurrent responsivity data that redshift and broaden with increasing reverse bias. Photocurrent spectra are quantitatively fit over a broad photon energy range to an XFK model using only a single fit parameter that determines the lineshape, the local bias ($V_{l}$), uniquely determining the local Electric Field maximum and depletion widths. As expected, the spectrally determined values of $V_{l}$ vary linearly with the applied bias ($V$) and reveal a large reduction in the local Electric Field due to electrostatic non-uniformity. The built-in bias ($V_{bi}$) is estimated by extrapolating $V_{l}$ at $V=0$, which compared with independent C-V Measurements indicates an overall $\pm$0.31 V accuracy of $V_{l}$. This demonstrates sub-bandgap photocurrent spectroscopy as a local probe of Electric Field in wide bandgap diodes that can be used to map out regions of device breakdown (hot spots) for improving electrostatic design of high voltage devices.