Branimir Blagojevic | NASA Goddard Space Flight Center (original) (raw)
Papers by Branimir Blagojevic
Journal of Physical and Chemical Reference Data, Aug 31, 2023
This review article compares new experimental and corresponding semiclassical Stark broadened dat... more This review article compares new experimental and corresponding semiclassical Stark broadened data for non-hydrogenic spectral lines of neutral atoms and positive ions. The review covers the period 2008 until the end of the 2020, and presents the continuation of previous critical reviews from 1976 (two), 1984 (two), 1990, 2002, and one from the 2009. This review reports the Stark broadening parameters of 1665 spectral lines belonging to the 35 elements with 61 different atomic and ion species. The data are taken from 60 papers. Experimental data are arranged by elements and spectra, and these are reported in tables in alphabetical and numerical order, respectively. Each experimental Stark broadening parameter is followed with estimated accuracy. The experimental Stark broadening and shift data presented in the tables are compared with corresponding semiclassical results available in the literature. In addition, for comparison experiments versus semiclassical theoretical Stark broadening parameters, a numerically improved theoretical approach developed based on Griem and co-workers' theory is used to evaluate Stark widths and shifts of all studied lines whenever required atomic energy levels data and transition probabilities are available. At the end of the text report, for each analyzed neutral or ion specie, the information about the location of the same species data in preceding reviews is given.
Journal of Physical and Chemical Reference Data, 2023
This review article compares new experimental and corresponding semiclassical Stark broadened dat... more This review article compares new experimental and corresponding semiclassical Stark broadened data for non-hydrogenic spectral lines of neutral atoms and positive ions. The review covers the period 2008 until the end of the 2020, and presents the continuation of previous critical reviews from 1976 (two), 1984 (two), 1990, 2002, and one from the 2009. This review reports the Stark broadening parameters of 1665 spectral lines belonging to the 35 elements with 61 different atomic and ion species. The data are taken from 60 papers. Experimental data are arranged by elements and spectra, and these are reported in tables in alphabetical and numerical order, respectively. Each experimental Stark broadening parameter is followed with estimated accuracy. The experimental Stark broadening and shift data presented in the tables are compared with corresponding semiclassical results available in the literature. In addition, for comparison experiments versus semiclassical theoretical Stark broadening parameters, a numerically improved theoretical approach developed based on Griem and co-workers' theory is used to evaluate Stark widths and shifts of all studied lines whenever required atomic energy levels data and transition probabilities are available. At the end of the text report, for each analyzed neutral or ion specie, the information about the location of the same species data in preceding reviews is given.
This paper reports the results of the spectroscopic electron temperature (Te) measurements in pla... more This paper reports the results of the spectroscopic electron temperature (Te) measurements in plasmas with electron densities ranging (0.3 -1.4)·10 17 cm -3 . The results of Te measurements obtained from various spectroscopic methods are mutually compared and discussed in relation to the condition for partial local thermodynamic equilibrium (PLTE). For the cases when the application of the spectroscopic techniques for Te measurements can not be justified on the bases of PLTE criterion, new method for determination of plasma electron temperature is proposed and tested.
Physical Review A
We have used an electron beam ion trap to observe a visible line at 598.30�13� nm that correspond... more We have used an electron beam ion trap to observe a visible line at 598.30�13� nm that corresponds to the 4d9 2D3/2−4d9 2D5/2 magnetic dipole transition within the ground state configuration of Xe9+. We have found no evidence to support the claim by others that a line near this position originates from Xe31+. The comparison of the measured wavelength with previous indirect experimental values, and the dependence of the line intensity on the electron beam energy, confirms the validity of the present identification. Our measured wavelength is in agreement with semiempirical Hartree-Fock calculations but shows a discrepancy with ab initio multiconfiguration Dirac-Fock calculations. We propose that the line may be useful as a diagnostic for extreme ultraviolet lithography light sources.
The Ultraviolet Biological Trigger Lidar (UBTL) is a laser-induced-fluorescence bio-aerosol senso... more The Ultraviolet Biological Trigger Lidar (UBTL) is a laser-induced-fluorescence bio-aerosol sensor designed to detect and discriminate bio-warfare-agent (BWA) simulants over short (less than 1 km) atmospheric paths. It was developed as a lidar-testbed for DARPA under their Semiconductor Ultraviolet Sources (SUVOS) Program and was upgraded in 2005 and early 2006 to have three laser sources, an improved near-infrared photo-counting module, and the ability to sense aerosol fluorescence in the ultraviolet spectrum. These optical upgrades accompanied by upgraded FPGA data system electronics, gave UBTL the ability to simultaneously excite aerosols with 266 nm, 355 nm, and 1047 nm laser pulses and then observe and record their elastic backscatter and UV (~ 300 nm) and visible (~ 440 nm) wavelength fluorescence for a total of six data channels. With sub-300 nm laser excitation, a fluorescence channel centered at 295 nm, and near-infrared elastic backscatter we demonstrated daytime detection...
Review of Scientific Instruments, 2003
The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating based imaging sp... more The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating based imaging spectrometer for the ultrasoft X-ray (USXR, 10-300 Å) range. The spectrometer will be integrated into an impurity diagnostic package for magnetic fusion experiments, which provides time and space resolved information about radiation losses, Zeff profiles and particle transport. The spectrometer has a simple layout, consisting of collimating and space resolving slits, a transmission grating and a 2-D imaging USXR detector. We tested two types of detectors, a CsI coated multi-channel plate and a phosphor P45 coated fiber optic plate, both with intensified CCD image readout. The performance of the 5000 l/mm, 3:1 bar to open area ratio transmission grating has been evaluated in the laboratory using Kα lines from a Manson source and the emission from a Penning discharge. A prototype spectrometer equiped with the first type detector and optimized for 6 Å spectral resolution has been tested successfully on the CDX-U tokamak at PPPL. A spectrometer using the second detector version has been developed for the NSTX spherical torus at Princeton. Spatially resolved spectra have been recorded with 25 -250 ms time integration with both spectrometers. In both experiments, spectra are dominated by low Z impurities C, N and O.
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1994
The Stark widths of the 3s 2 S-3p 2 P 0 and 3p 2 P 0 -3d 2 D transitions have been calculated and... more The Stark widths of the 3s 2 S-3p 2 P 0 and 3p 2 P 0 -3d 2 D transitions have been calculated and measured in the plasma of a pulsed arc. Electron densities in the range (2.l-6.4)X 10 17 cm-3 were determined from the width of the He II Pa line while electron temperatures between 50 800 and 131 800 K are measured from the Boltzmann plot of 0 IV line intensities. Our experimental 0 IV Stark width agrees well with another experiment and with our semiclassical theoretical results in the whole temperature range.
Review of Scientific Instruments, 2003
An innovative fast system for x-ray imaging has been developed at ENEA-Frascati, Italy, in collab... more An innovative fast system for x-ray imaging has been developed at ENEA-Frascati, Italy, in collaboration with INFN-Pisa, Italy. It is based on a pinhole camera coupled to a micropattern gas detector ͑MPGD͒ having a gas electron multiplier ͑GEM͒ as amplifying stage. This detector (2.5 cmϫ2.5 cm active area͒ is equipped with a two dimensional readout printed circuit board with 144 pixels (12ϫ12). It is able to get x-ray images of the plasma at very high framing rate ͑up to 100 kHz͒ in a selectable x-ray energy range, with different magnifications or views of the plasma. The system has been tested successfully on the Frascati Tokamak Upgrade ͑FTU͒ during Summer 2001, with a one-dimensional perpendicular view of the plasma. In collaboration with ENEA, the Johns Hopkins University ͑JHU͒ and Princeton Plasma Physics ͑PPPL͒, this system has been setup and calibrated in the x-ray energy range 3-8 keV and it has been installed, with a tangential view, on the NSTX experiment at PPPL. Time resolved, two-dimensional x-ray images of the NSTX plasma core will be presented, with different magnifications and different orientations of the optical axis of the x-ray pinhole camera. Fast acquisitions, performed up to 50 kHz of framing rate, allow the study of the plasma evolution and the 2D shaping during MHD activity.
Solid State Lasers XXIII: Technology and Devices, 2014
We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adaptin... more We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:VO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:VO4 laser has a fundamental wavelength that is tunable from 1063-1067 nm. A CW External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nm. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nm. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9W @ 532 nm wavelength Nd:VO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.
Emerging Lithographic Technologies V, 2001
In this work, ablative and gas capillary discharges have been investigated as potential sources f... more In this work, ablative and gas capillary discharges have been investigated as potential sources for the EUV lithography technology. Carbon and lithium ablative discharge spectroscopy and EUV energy measurements have been performed. Gas (O 2 , Ne, Ar, Kr and Xe) capillary discharge were powered by fast, nanosecond, high voltage Blumlein-like pulser. Detailed investigation of capillary length and diameter, gas pressure, capacitance and inductance of the electrical driver are documented. The energy density, expressed in J cm -3 , appears as a monitoring factor for an efficient production of 13.5 nm radiation band. The measurement and the evaluation of measurement uncertainties lead to the conclusion that the in band, 13.5 nm ± 0.9 nm, energy radiated by the Xe lamp developed in this work ranges from 0.5 mJ/sr/shot to 20 mJ/sr/shot for a 7 J energy input. Repetition rate investigation of the first prototype have shown operation at 50 Hz in continuous mode and up to 350 Hz in burst mode.
The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating (TG) based imagi... more The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating (TG) based imaging spectrometer for the soft and ultrasoft X-ray (USXR) ranges. The spectrometer will be integrated into a multi-purpose impurity diagnostic package for Magnetically Confined Fusion experiments, which will provide time and space resolved information about radiation losses, Zeff profiles and particle transport. The package will also include
We are developing MHD and turbulence diagnostics which will image rapid fluctuations (on the scal... more We are developing MHD and turbulence diagnostics which will image rapid fluctuations (on the scale of tens of kHz) of relatively weak fluctuations of soft and ultrasoft X-ray emission from Magnetically Confined Fusion plasmas. Paramount to these systems is finding soft X-ray to visible light converters having less than a few µs decay time and high conversion efficiencies. We performed
Review of Scientific Instruments, 2005
A custom, flat field, extreme ultraviolet EUV spectrometer built specifically for use with low po... more A custom, flat field, extreme ultraviolet EUV spectrometer built specifically for use with low power light sources that operate under ultrahigh vacuum conditions is reported. The spectral range of the spectrometer extends from 4 nm to 40 nm. The instrument optimizes the light gathering power and signal to noise ratio while achieving good resolution. A detailed description of the spectrometer and design considerations are presented, as well as a novel procedure that could be used to obtain a synthetic wavelength calibration with the aid of only a single known spectral feature. This synthetic wavelength calibration is compared to a standard wavelength calibration obtained from previously reported spectral lines of Xe, Ar and Ne ions recorded with this spectrometer.
Physical Review A, 2006
We have used an electron beam ion trap to observe a visible line at 598.30͑13͒ nm that correspond... more We have used an electron beam ion trap to observe a visible line at 598.30͑13͒ nm that corresponds to the 4d 9 2 D 3/2 −4d 9 2 D 5/2 magnetic dipole transition within the ground state configuration of Xe 9+ . We have found no evidence to support the claim by others that a line near this position originates from Xe 31+ . The comparison of the measured wavelength with previous indirect experimental values, and the dependence of the line intensity on the electron beam energy, confirms the validity of the present identification. Our measured wavelength is in agreement with semiempirical Hartree-Fock calculations but shows a discrepancy with ab initio multiconfiguration Dirac-Fock calculations. We propose that the line may be useful as a diagnostic for extreme ultraviolet lithography light sources.
Physica Scripta, 2001
In order to test the prediction of the LS coupling approximation for several light elements (B, C... more In order to test the prediction of the LS coupling approximation for several light elements (B, C, N, O, F and Ne), the line intensity ratios of the 3s^3p multiplets along the isoelectronic sequences of lithium and beryllium and line intensity ratios of 3s^3p and 3p^3d multiplets along isoelectronic sequences of boron, carbon, nitrogen, oxygen and £uorine have been investigated experimentally. The light sources were two low-pressure pulsed arcs. The plasma electron densities were determined from the width of the He II P a line.
Nuclear Fusion, 2003
A major research goal of the national spherical torus experiment is establishing long-pulse, high... more A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, high confinement operation and its physics basis. This research has been enabled by facility capabilities developed during 2001 and 2002, including neutral beam (up to 7 MW) and high harmonic fast wave (HHFW) heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of plasmas with β T ≡ p /(B 2 T0 /2µ 0 ) of up to 35%. Normalized beta values often exceed the no-wall limit, and studies suggest that passive wall mode stabilization enables this for H mode plasmas with broad pressure profiles. The viability of long, high bootstrap current fraction operations has been established for ELMing H mode plasmas with toroidal beta values in excess of 15% and sustained for several current relaxation times. Improvements in wall conditioning and fuelling are likely contributing to a reduction in H mode power thresholds. Electron thermal conduction is the dominant thermal loss channel in auxiliary heated plasmas examined thus far. HHFW effectively heats electrons, and its acceleration of fast beam ions has been observed. Evidence for HHFW current drive is obtained by comparision of the loop voltage evolution in plasmas with matched density and temperature profiles but varying phases of launched HHFW waves. Studies of emissions from electron Bernstein waves indicate a density scale length dependence of their transmission across the upper hybrid resonance near the plasma edge that is consistent with theoretical predictions. A peak heat flux to the divertor targets of 10 MW m −2 has been measured in the H mode, with large asymmetries being observed in the power deposition between the inner and outer strike points. Non-inductive plasma startup studies have focused on coaxial helicity injection. With this technique, toroidal currents up to 400 kA have been driven, and studies to assess flux closure and coupling to other current drive techniques have begun.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2000
This paper reports the results of the spectroscopic electron temperature (¹ ) measurements in pla... more This paper reports the results of the spectroscopic electron temperature (¹ ) measurements in plasmas with electron densities ranging (0.3}1.4);10 cm\. The results of ¹ measurements obtained from various spectroscopic methods are mutually compared and discussed in relation to the condition for partial local thermodynamic equilibrium (PLTE). For the cases when the application of the spectroscopic techniques for ¹ measurements cannot be justi"ed on the bases of PLTE criterion, new method for determination of plasma electron temperature is proposed and tested. Measurements of plasma parameters, electron temperature and electron density were performed in a low-pressure pulsed arc in helium with small admixture of nitrogen or oxygen whose ions were used as thermometric species. The electron densities were determined from the width of the He II P ? 468.6 nm line.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2000
The Stark widths of spectral lines belonging to the 3s}3p and 3p}3d transitions of doubly ionized... more The Stark widths of spectral lines belonging to the 3s}3p and 3p}3d transitions of doubly ionized C, N, O, F and Ne have been measured in the plasma of low-pressure pulsed arc. The plasma electron densities were determined from the width of the He II P line while the electron temperatures were measured from relative intensities of N II lines. The experimental results are compared with other theoretical and experimental data. Comparisons of the experimental and theoretical data along isoelectronic sequences were also performed.
Journal of Physical and Chemical Reference Data, Aug 31, 2023
This review article compares new experimental and corresponding semiclassical Stark broadened dat... more This review article compares new experimental and corresponding semiclassical Stark broadened data for non-hydrogenic spectral lines of neutral atoms and positive ions. The review covers the period 2008 until the end of the 2020, and presents the continuation of previous critical reviews from 1976 (two), 1984 (two), 1990, 2002, and one from the 2009. This review reports the Stark broadening parameters of 1665 spectral lines belonging to the 35 elements with 61 different atomic and ion species. The data are taken from 60 papers. Experimental data are arranged by elements and spectra, and these are reported in tables in alphabetical and numerical order, respectively. Each experimental Stark broadening parameter is followed with estimated accuracy. The experimental Stark broadening and shift data presented in the tables are compared with corresponding semiclassical results available in the literature. In addition, for comparison experiments versus semiclassical theoretical Stark broadening parameters, a numerically improved theoretical approach developed based on Griem and co-workers' theory is used to evaluate Stark widths and shifts of all studied lines whenever required atomic energy levels data and transition probabilities are available. At the end of the text report, for each analyzed neutral or ion specie, the information about the location of the same species data in preceding reviews is given.
Journal of Physical and Chemical Reference Data, 2023
This review article compares new experimental and corresponding semiclassical Stark broadened dat... more This review article compares new experimental and corresponding semiclassical Stark broadened data for non-hydrogenic spectral lines of neutral atoms and positive ions. The review covers the period 2008 until the end of the 2020, and presents the continuation of previous critical reviews from 1976 (two), 1984 (two), 1990, 2002, and one from the 2009. This review reports the Stark broadening parameters of 1665 spectral lines belonging to the 35 elements with 61 different atomic and ion species. The data are taken from 60 papers. Experimental data are arranged by elements and spectra, and these are reported in tables in alphabetical and numerical order, respectively. Each experimental Stark broadening parameter is followed with estimated accuracy. The experimental Stark broadening and shift data presented in the tables are compared with corresponding semiclassical results available in the literature. In addition, for comparison experiments versus semiclassical theoretical Stark broadening parameters, a numerically improved theoretical approach developed based on Griem and co-workers' theory is used to evaluate Stark widths and shifts of all studied lines whenever required atomic energy levels data and transition probabilities are available. At the end of the text report, for each analyzed neutral or ion specie, the information about the location of the same species data in preceding reviews is given.
This paper reports the results of the spectroscopic electron temperature (Te) measurements in pla... more This paper reports the results of the spectroscopic electron temperature (Te) measurements in plasmas with electron densities ranging (0.3 -1.4)·10 17 cm -3 . The results of Te measurements obtained from various spectroscopic methods are mutually compared and discussed in relation to the condition for partial local thermodynamic equilibrium (PLTE). For the cases when the application of the spectroscopic techniques for Te measurements can not be justified on the bases of PLTE criterion, new method for determination of plasma electron temperature is proposed and tested.
Physical Review A
We have used an electron beam ion trap to observe a visible line at 598.30�13� nm that correspond... more We have used an electron beam ion trap to observe a visible line at 598.30�13� nm that corresponds to the 4d9 2D3/2−4d9 2D5/2 magnetic dipole transition within the ground state configuration of Xe9+. We have found no evidence to support the claim by others that a line near this position originates from Xe31+. The comparison of the measured wavelength with previous indirect experimental values, and the dependence of the line intensity on the electron beam energy, confirms the validity of the present identification. Our measured wavelength is in agreement with semiempirical Hartree-Fock calculations but shows a discrepancy with ab initio multiconfiguration Dirac-Fock calculations. We propose that the line may be useful as a diagnostic for extreme ultraviolet lithography light sources.
The Ultraviolet Biological Trigger Lidar (UBTL) is a laser-induced-fluorescence bio-aerosol senso... more The Ultraviolet Biological Trigger Lidar (UBTL) is a laser-induced-fluorescence bio-aerosol sensor designed to detect and discriminate bio-warfare-agent (BWA) simulants over short (less than 1 km) atmospheric paths. It was developed as a lidar-testbed for DARPA under their Semiconductor Ultraviolet Sources (SUVOS) Program and was upgraded in 2005 and early 2006 to have three laser sources, an improved near-infrared photo-counting module, and the ability to sense aerosol fluorescence in the ultraviolet spectrum. These optical upgrades accompanied by upgraded FPGA data system electronics, gave UBTL the ability to simultaneously excite aerosols with 266 nm, 355 nm, and 1047 nm laser pulses and then observe and record their elastic backscatter and UV (~ 300 nm) and visible (~ 440 nm) wavelength fluorescence for a total of six data channels. With sub-300 nm laser excitation, a fluorescence channel centered at 295 nm, and near-infrared elastic backscatter we demonstrated daytime detection...
Review of Scientific Instruments, 2003
The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating based imaging sp... more The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating based imaging spectrometer for the ultrasoft X-ray (USXR, 10-300 Å) range. The spectrometer will be integrated into an impurity diagnostic package for magnetic fusion experiments, which provides time and space resolved information about radiation losses, Zeff profiles and particle transport. The spectrometer has a simple layout, consisting of collimating and space resolving slits, a transmission grating and a 2-D imaging USXR detector. We tested two types of detectors, a CsI coated multi-channel plate and a phosphor P45 coated fiber optic plate, both with intensified CCD image readout. The performance of the 5000 l/mm, 3:1 bar to open area ratio transmission grating has been evaluated in the laboratory using Kα lines from a Manson source and the emission from a Penning discharge. A prototype spectrometer equiped with the first type detector and optimized for 6 Å spectral resolution has been tested successfully on the CDX-U tokamak at PPPL. A spectrometer using the second detector version has been developed for the NSTX spherical torus at Princeton. Spatially resolved spectra have been recorded with 25 -250 ms time integration with both spectrometers. In both experiments, spectra are dominated by low Z impurities C, N and O.
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1994
The Stark widths of the 3s 2 S-3p 2 P 0 and 3p 2 P 0 -3d 2 D transitions have been calculated and... more The Stark widths of the 3s 2 S-3p 2 P 0 and 3p 2 P 0 -3d 2 D transitions have been calculated and measured in the plasma of a pulsed arc. Electron densities in the range (2.l-6.4)X 10 17 cm-3 were determined from the width of the He II Pa line while electron temperatures between 50 800 and 131 800 K are measured from the Boltzmann plot of 0 IV line intensities. Our experimental 0 IV Stark width agrees well with another experiment and with our semiclassical theoretical results in the whole temperature range.
Review of Scientific Instruments, 2003
An innovative fast system for x-ray imaging has been developed at ENEA-Frascati, Italy, in collab... more An innovative fast system for x-ray imaging has been developed at ENEA-Frascati, Italy, in collaboration with INFN-Pisa, Italy. It is based on a pinhole camera coupled to a micropattern gas detector ͑MPGD͒ having a gas electron multiplier ͑GEM͒ as amplifying stage. This detector (2.5 cmϫ2.5 cm active area͒ is equipped with a two dimensional readout printed circuit board with 144 pixels (12ϫ12). It is able to get x-ray images of the plasma at very high framing rate ͑up to 100 kHz͒ in a selectable x-ray energy range, with different magnifications or views of the plasma. The system has been tested successfully on the Frascati Tokamak Upgrade ͑FTU͒ during Summer 2001, with a one-dimensional perpendicular view of the plasma. In collaboration with ENEA, the Johns Hopkins University ͑JHU͒ and Princeton Plasma Physics ͑PPPL͒, this system has been setup and calibrated in the x-ray energy range 3-8 keV and it has been installed, with a tangential view, on the NSTX experiment at PPPL. Time resolved, two-dimensional x-ray images of the NSTX plasma core will be presented, with different magnifications and different orientations of the optical axis of the x-ray pinhole camera. Fast acquisitions, performed up to 50 kHz of framing rate, allow the study of the plasma evolution and the 2D shaping during MHD activity.
Solid State Lasers XXIII: Technology and Devices, 2014
We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adaptin... more We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:VO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:VO4 laser has a fundamental wavelength that is tunable from 1063-1067 nm. A CW External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nm. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nm. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9W @ 532 nm wavelength Nd:VO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.
Emerging Lithographic Technologies V, 2001
In this work, ablative and gas capillary discharges have been investigated as potential sources f... more In this work, ablative and gas capillary discharges have been investigated as potential sources for the EUV lithography technology. Carbon and lithium ablative discharge spectroscopy and EUV energy measurements have been performed. Gas (O 2 , Ne, Ar, Kr and Xe) capillary discharge were powered by fast, nanosecond, high voltage Blumlein-like pulser. Detailed investigation of capillary length and diameter, gas pressure, capacitance and inductance of the electrical driver are documented. The energy density, expressed in J cm -3 , appears as a monitoring factor for an efficient production of 13.5 nm radiation band. The measurement and the evaluation of measurement uncertainties lead to the conclusion that the in band, 13.5 nm ± 0.9 nm, energy radiated by the Xe lamp developed in this work ranges from 0.5 mJ/sr/shot to 20 mJ/sr/shot for a 7 J energy input. Repetition rate investigation of the first prototype have shown operation at 50 Hz in continuous mode and up to 350 Hz in burst mode.
The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating (TG) based imagi... more The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating (TG) based imaging spectrometer for the soft and ultrasoft X-ray (USXR) ranges. The spectrometer will be integrated into a multi-purpose impurity diagnostic package for Magnetically Confined Fusion experiments, which will provide time and space resolved information about radiation losses, Zeff profiles and particle transport. The package will also include
We are developing MHD and turbulence diagnostics which will image rapid fluctuations (on the scal... more We are developing MHD and turbulence diagnostics which will image rapid fluctuations (on the scale of tens of kHz) of relatively weak fluctuations of soft and ultrasoft X-ray emission from Magnetically Confined Fusion plasmas. Paramount to these systems is finding soft X-ray to visible light converters having less than a few µs decay time and high conversion efficiencies. We performed
Review of Scientific Instruments, 2005
A custom, flat field, extreme ultraviolet EUV spectrometer built specifically for use with low po... more A custom, flat field, extreme ultraviolet EUV spectrometer built specifically for use with low power light sources that operate under ultrahigh vacuum conditions is reported. The spectral range of the spectrometer extends from 4 nm to 40 nm. The instrument optimizes the light gathering power and signal to noise ratio while achieving good resolution. A detailed description of the spectrometer and design considerations are presented, as well as a novel procedure that could be used to obtain a synthetic wavelength calibration with the aid of only a single known spectral feature. This synthetic wavelength calibration is compared to a standard wavelength calibration obtained from previously reported spectral lines of Xe, Ar and Ne ions recorded with this spectrometer.
Physical Review A, 2006
We have used an electron beam ion trap to observe a visible line at 598.30͑13͒ nm that correspond... more We have used an electron beam ion trap to observe a visible line at 598.30͑13͒ nm that corresponds to the 4d 9 2 D 3/2 −4d 9 2 D 5/2 magnetic dipole transition within the ground state configuration of Xe 9+ . We have found no evidence to support the claim by others that a line near this position originates from Xe 31+ . The comparison of the measured wavelength with previous indirect experimental values, and the dependence of the line intensity on the electron beam energy, confirms the validity of the present identification. Our measured wavelength is in agreement with semiempirical Hartree-Fock calculations but shows a discrepancy with ab initio multiconfiguration Dirac-Fock calculations. We propose that the line may be useful as a diagnostic for extreme ultraviolet lithography light sources.
Physica Scripta, 2001
In order to test the prediction of the LS coupling approximation for several light elements (B, C... more In order to test the prediction of the LS coupling approximation for several light elements (B, C, N, O, F and Ne), the line intensity ratios of the 3s^3p multiplets along the isoelectronic sequences of lithium and beryllium and line intensity ratios of 3s^3p and 3p^3d multiplets along isoelectronic sequences of boron, carbon, nitrogen, oxygen and £uorine have been investigated experimentally. The light sources were two low-pressure pulsed arcs. The plasma electron densities were determined from the width of the He II P a line.
Nuclear Fusion, 2003
A major research goal of the national spherical torus experiment is establishing long-pulse, high... more A major research goal of the national spherical torus experiment is establishing long-pulse, high beta, high confinement operation and its physics basis. This research has been enabled by facility capabilities developed during 2001 and 2002, including neutral beam (up to 7 MW) and high harmonic fast wave (HHFW) heating (up to 6 MW), toroidal fields up to 6 kG, plasma currents up to 1.5 MA, flexible shape control, and wall preparation techniques. These capabilities have enabled the generation of plasmas with β T ≡ p /(B 2 T0 /2µ 0 ) of up to 35%. Normalized beta values often exceed the no-wall limit, and studies suggest that passive wall mode stabilization enables this for H mode plasmas with broad pressure profiles. The viability of long, high bootstrap current fraction operations has been established for ELMing H mode plasmas with toroidal beta values in excess of 15% and sustained for several current relaxation times. Improvements in wall conditioning and fuelling are likely contributing to a reduction in H mode power thresholds. Electron thermal conduction is the dominant thermal loss channel in auxiliary heated plasmas examined thus far. HHFW effectively heats electrons, and its acceleration of fast beam ions has been observed. Evidence for HHFW current drive is obtained by comparision of the loop voltage evolution in plasmas with matched density and temperature profiles but varying phases of launched HHFW waves. Studies of emissions from electron Bernstein waves indicate a density scale length dependence of their transmission across the upper hybrid resonance near the plasma edge that is consistent with theoretical predictions. A peak heat flux to the divertor targets of 10 MW m −2 has been measured in the H mode, with large asymmetries being observed in the power deposition between the inner and outer strike points. Non-inductive plasma startup studies have focused on coaxial helicity injection. With this technique, toroidal currents up to 400 kA have been driven, and studies to assess flux closure and coupling to other current drive techniques have begun.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2000
This paper reports the results of the spectroscopic electron temperature (¹ ) measurements in pla... more This paper reports the results of the spectroscopic electron temperature (¹ ) measurements in plasmas with electron densities ranging (0.3}1.4);10 cm\. The results of ¹ measurements obtained from various spectroscopic methods are mutually compared and discussed in relation to the condition for partial local thermodynamic equilibrium (PLTE). For the cases when the application of the spectroscopic techniques for ¹ measurements cannot be justi"ed on the bases of PLTE criterion, new method for determination of plasma electron temperature is proposed and tested. Measurements of plasma parameters, electron temperature and electron density were performed in a low-pressure pulsed arc in helium with small admixture of nitrogen or oxygen whose ions were used as thermometric species. The electron densities were determined from the width of the He II P ? 468.6 nm line.
Journal of Quantitative Spectroscopy and Radiative Transfer, 2000
The Stark widths of spectral lines belonging to the 3s}3p and 3p}3d transitions of doubly ionized... more The Stark widths of spectral lines belonging to the 3s}3p and 3p}3d transitions of doubly ionized C, N, O, F and Ne have been measured in the plasma of low-pressure pulsed arc. The plasma electron densities were determined from the width of the He II P line while the electron temperatures were measured from relative intensities of N II lines. The experimental results are compared with other theoretical and experimental data. Comparisons of the experimental and theoretical data along isoelectronic sequences were also performed.