Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6633509
M. Ilkov, A. Manolescu, Á. Valfells, A. Pedersen
Summary form only given. Vacuum diodes with gap spacing of the order 1μm and gap voltages of the order 1V exhibit space-charge induced current modulation in the THz regime. The frequency can be tuned by simply altering the applied DC vacuum electric field, and the frequency range corresponding to the range of the applied field can be set by selection of the size of the emitter area on the cathode. The current in a microdiode of this type will typically range from tens to hundreds of microamperes, thus limiting the THz power that can be drawn from a single microdiode. Coupling between microdiodes is a problem of interest as it could offer an avenue to generate higher power levels by using an array of emitters. We present an overview of work done on vacuum microdiode oscillators, with some new results concerning beam quality in a single microdiode and interaction between beams from neighboring emitters.
{"title":"Vacuum microdiodes as tunable THZ oscillators","authors":"M. Ilkov, A. Manolescu, Á. Valfells, A. Pedersen","doi":"10.1109/PLASMA.2013.6633509","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6633509","url":null,"abstract":"Summary form only given. Vacuum diodes with gap spacing of the order 1μm and gap voltages of the order 1V exhibit space-charge induced current modulation in the THz regime. The frequency can be tuned by simply altering the applied DC vacuum electric field, and the frequency range corresponding to the range of the applied field can be set by selection of the size of the emitter area on the cathode. The current in a microdiode of this type will typically range from tens to hundreds of microamperes, thus limiting the THz power that can be drawn from a single microdiode. Coupling between microdiodes is a problem of interest as it could offer an avenue to generate higher power levels by using an array of emitters. We present an overview of work done on vacuum microdiode oscillators, with some new results concerning beam quality in a single microdiode and interaction between beams from neighboring emitters.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88662100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6634965
I. Smith, V. Bailey, P. Corcoran, R. Stevens, J. Pearce, D. McGlathery, R. Altes, B. Oliver
An Induction Voltage Adder (IVA) is described that comprises six induction cells like those of RITS [1] and six pulse-forming-lines (pfls) like those of Hydrus [2]. The pfls are negatively-charged through a coaxial oil line fed from one end by a 15-stage Marx with 2.6 μF 100 kV capacitors. The IVA feeds a negative pulse to an electron diode through a 5m long output vacuum coax. Simulations for an operating level at which the IVA components have proved reliable show that on a load that falls in impedance from 50 to 25 ohms in about 50 ns, the voltage of >7 MV is approximately flat for about 60 ns because of the ramped pulse from the pfl. Peak current is about 250 kA.
{"title":"Simulation of an induction voltage adder in two polarities","authors":"I. Smith, V. Bailey, P. Corcoran, R. Stevens, J. Pearce, D. McGlathery, R. Altes, B. Oliver","doi":"10.1109/PLASMA.2013.6634965","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6634965","url":null,"abstract":"An Induction Voltage Adder (IVA) is described that comprises six induction cells like those of RITS [1] and six pulse-forming-lines (pfls) like those of Hydrus [2]. The pfls are negatively-charged through a coaxial oil line fed from one end by a 15-stage Marx with 2.6 μF 100 kV capacitors. The IVA feeds a negative pulse to an electron diode through a 5m long output vacuum coax. Simulations for an operating level at which the IVA components have proved reliable show that on a load that falls in impedance from 50 to 25 ohms in about 50 ns, the voltage of >7 MV is approximately flat for about 60 ns because of the ramped pulse from the pfl. Peak current is about 250 kA.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88744566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6634780
I. Golovkin, J. Macfarlane, P. Woodruff, S. Kulkarni, I. Hall, G. Gregori, J. Bailey, E. Harding, T. Ao
Summary form only given. Spectrally resolved x-ray scattering has become a very effective method for diagnosing electron temperatures, densities, and average ionization in warm dense matter. We present a newly implemented capability to simulate scattering signatures from realistic experimental configurations, which include the influence of plasma non-uniformities and collecting scattered x-rays from a range of angles. The method is based on a formalism developed by G. Gregori1. The x-ray scattering modeling has been added to the multidimensional collisional-radiative spectral and imaging package SPECT3D2. The ability to simulate the emissivity and attenuation of scattered photons within a multidimensional multi-volume-element plasma with non-uniform temperature and density distributions adds a major new capability to existing model. We will discuss details of the modeling and show results relevant to ongoing experimental investigations at Sandia National Laboratories.
{"title":"Spectroscopic and x-ray scattering models in SPECT3D","authors":"I. Golovkin, J. Macfarlane, P. Woodruff, S. Kulkarni, I. Hall, G. Gregori, J. Bailey, E. Harding, T. Ao","doi":"10.1109/PLASMA.2013.6634780","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6634780","url":null,"abstract":"Summary form only given. Spectrally resolved x-ray scattering has become a very effective method for diagnosing electron temperatures, densities, and average ionization in warm dense matter. We present a newly implemented capability to simulate scattering signatures from realistic experimental configurations, which include the influence of plasma non-uniformities and collecting scattered x-rays from a range of angles. The method is based on a formalism developed by G. Gregori1. The x-ray scattering modeling has been added to the multidimensional collisional-radiative spectral and imaging package SPECT3D2. The ability to simulate the emissivity and attenuation of scattered photons within a multidimensional multi-volume-element plasma with non-uniform temperature and density distributions adds a major new capability to existing model. We will discuss details of the modeling and show results relevant to ongoing experimental investigations at Sandia National Laboratories.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87338365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6635090
S. Umbarkar, S. Bindu, H. Mangalvedekar, P. C. Saroj, Archana Sharma, K. C. Mittal
Ultra Wideband (UWB) system has many applications such as target object detection, transient radar, mine clearing, detection of crack on underground pipeline, water purification, electronic effects testing, and jamming. This system consists of Marx generator, peaking capacitor, peaking switch and radiating element (antenna). The complete transient analysis of half transverse electromagnetic (HTEM) horn antenna integrated to the peaking stage is modeled in CST microwave studio. The simulation model has triangular excitation input pulse feed to the peaking stage with 25 ns rise time, 150 ns pulse width and 113.75 kV peak amplitude. The radiated E far field is measured at 15 m distance gives the rise time 232 ps, pulse length 25 ns, and peak amplitude 14.886kV/m. The experiment for the same has been conducted and the E field is measured up to 50 m distance. The radiated field in the experiment is measured in open air. The amplitude of the maximum radiated far field, measured by using B dot sensor probe at different distance is match with the modeling results. The mathematical model is developed in MATLAB Simulink to calculate effect of step input on E far field radiation.
{"title":"PPPS-2013: Abstract: Analysis of half TEM horn antenna for high power UWB system","authors":"S. Umbarkar, S. Bindu, H. Mangalvedekar, P. C. Saroj, Archana Sharma, K. C. Mittal","doi":"10.1109/PLASMA.2013.6635090","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6635090","url":null,"abstract":"Ultra Wideband (UWB) system has many applications such as target object detection, transient radar, mine clearing, detection of crack on underground pipeline, water purification, electronic effects testing, and jamming. This system consists of Marx generator, peaking capacitor, peaking switch and radiating element (antenna). The complete transient analysis of half transverse electromagnetic (HTEM) horn antenna integrated to the peaking stage is modeled in CST microwave studio. The simulation model has triangular excitation input pulse feed to the peaking stage with 25 ns rise time, 150 ns pulse width and 113.75 kV peak amplitude. The radiated E far field is measured at 15 m distance gives the rise time 232 ps, pulse length 25 ns, and peak amplitude 14.886kV/m. The experiment for the same has been conducted and the E field is measured up to 50 m distance. The radiated field in the experiment is measured in open air. The amplitude of the maximum radiated far field, measured by using B dot sensor probe at different distance is match with the modeling results. The mathematical model is developed in MATLAB Simulink to calculate effect of step input on E far field radiation.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87362931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6633182
J. Haack, I. Gamba
Summary form only given. We present recent work extending the conservative spectral method for the Boltzmann transport equation developed by Gamba and Tharkabhushanam. This formulation is derived from the weak form of the Boltzmann equation, which represents the collisional term as a weighted convolution in Fourier space. We have extended the method to the case of anisotropic scattering cross sections and have investigated the grazing collisions limit of the Boltzmann equation with screened Coulomb potentials. We also present new results demonstating the method's versatility by simulating collisions with Lennard-Jones and other similar intermolecular potentials.
{"title":"Deterministic computation of the Boltzmann transport equation with anisotropic scattering cross section","authors":"J. Haack, I. Gamba","doi":"10.1109/PLASMA.2013.6633182","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6633182","url":null,"abstract":"Summary form only given. We present recent work extending the conservative spectral method for the Boltzmann transport equation developed by Gamba and Tharkabhushanam. This formulation is derived from the weak form of the Boltzmann equation, which represents the collisional term as a weighted convolution in Fourier space. We have extended the method to the case of anisotropic scattering cross sections and have investigated the grazing collisions limit of the Boltzmann equation with screened Coulomb potentials. We also present new results demonstating the method's versatility by simulating collisions with Lennard-Jones and other similar intermolecular potentials.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84696987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6633186
M. Alessandri, L. Calzà, V. Colombo, L. S. Dolci, A. Fiorani, M. L. Focarete, E. Ghedini, M. Gherardi, C. Gualandi, R. Laurita, A. Liguori, S. Quiroga, P. Sanibondi
Summary form only given.Material science applied to regenerative medicine and tissue engineering study the achievement of biocompatible artificial tissues to improve, self-repair or favour cellular therapies. Various studies prove plasma ability to modify polymeric scaffold surface, with an improvement of hydrophilicity and surface roughness demonstrated by a reduction of contact angle and by an increase of surface energy without altering bulk properties. Furthermore, it was demonstrated that cell cultures on plasma modified scaffolds display better proliferation and viability compared to pristine materials. In this work we focus on the use of atmospheric pressure non-thermal plasma for surface modification of electrospun poly(L-lactic acid) (PLLA) non-woven mats. The electrospinning technology allows to fabricate scaffolds of polymeric materials with highly porous structure, interconnected pores and large specific surface area, that mimic extracellular matrix (ECM). In this work results will be presented concerning the process of exposure of electrospun scaffolds to the plasma region generated by three different plasma sources operated at atmospheric pressure: a floating electrode dielectric barrier discharge (FE-DBD), a linear corona discharge and a DBD roller. A high voltage generator capable of producing pulses with a rise rate in the order of some kV/ns has been used. All the sources are easily scaled-up in the frame of a “large area treatment” approach. Plasma sources characterization has been carried out through a wide set of measurements, changing operating conditions, geometry and plasma gas composition, as the fundamental stage in a multi-step approach for process optimization. In this work, results on the effect of plasma treatment on morphology, thermo-mechanical and surface properties of PLLA electrospun nanofibrous mats will be presented. Results for the introduction of COOH functional group on PLLA electrospun scaffold and for the proliferation of rat embryonic stem cells (RESCs) grown on plasma treated and untreated PLLA electrospun scaffolds will be presented and discussed.
{"title":"Atmospheric plasma surface modification of electrospun poly(L-lactic acid): Effect on mat properties and cell culturing","authors":"M. Alessandri, L. Calzà, V. Colombo, L. S. Dolci, A. Fiorani, M. L. Focarete, E. Ghedini, M. Gherardi, C. Gualandi, R. Laurita, A. Liguori, S. Quiroga, P. Sanibondi","doi":"10.1109/PLASMA.2013.6633186","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6633186","url":null,"abstract":"Summary form only given.Material science applied to regenerative medicine and tissue engineering study the achievement of biocompatible artificial tissues to improve, self-repair or favour cellular therapies. Various studies prove plasma ability to modify polymeric scaffold surface, with an improvement of hydrophilicity and surface roughness demonstrated by a reduction of contact angle and by an increase of surface energy without altering bulk properties. Furthermore, it was demonstrated that cell cultures on plasma modified scaffolds display better proliferation and viability compared to pristine materials. In this work we focus on the use of atmospheric pressure non-thermal plasma for surface modification of electrospun poly(L-lactic acid) (PLLA) non-woven mats. The electrospinning technology allows to fabricate scaffolds of polymeric materials with highly porous structure, interconnected pores and large specific surface area, that mimic extracellular matrix (ECM). In this work results will be presented concerning the process of exposure of electrospun scaffolds to the plasma region generated by three different plasma sources operated at atmospheric pressure: a floating electrode dielectric barrier discharge (FE-DBD), a linear corona discharge and a DBD roller. A high voltage generator capable of producing pulses with a rise rate in the order of some kV/ns has been used. All the sources are easily scaled-up in the frame of a “large area treatment” approach. Plasma sources characterization has been carried out through a wide set of measurements, changing operating conditions, geometry and plasma gas composition, as the fundamental stage in a multi-step approach for process optimization. In this work, results on the effect of plasma treatment on morphology, thermo-mechanical and surface properties of PLLA electrospun nanofibrous mats will be presented. Results for the introduction of COOH functional group on PLLA electrospun scaffold and for the proliferation of rat embryonic stem cells (RESCs) grown on plasma treated and untreated PLLA electrospun scaffolds will be presented and discussed.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90647655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6635056
B. Kupczyk, Chien‐Hao Liu, X. Xiang, N. Behdad, J. Scharer, J. Booske
Summary form only given. Development of high power microwave (HPM) distributed discharge limiters relies critically on minimizing the delay time between HPM incidence and diffuse plasma creation. We present a range of pulsed plasma experiments conducted in neon, argon, helium, and mixtures of these gases, from 50-760 torr. Breakdown is achieved by illuminating a gas cell with a ~25kW, ~2 kV/cm, 800ns-long pulse as well as 41Hz pulse trains. Current results focus on preliminary experiments with metamaterial window coatings that indicate significant improvement opportunities for controlling breakdown thresholds and reducing breakdown delay. New results with gas mixtures in which observed breakdown occurs in <;100ns are also presented.
{"title":"Reduced breakdown delay in high power microwave dielectric window discharges","authors":"B. Kupczyk, Chien‐Hao Liu, X. Xiang, N. Behdad, J. Scharer, J. Booske","doi":"10.1109/PLASMA.2013.6635056","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6635056","url":null,"abstract":"Summary form only given. Development of high power microwave (HPM) distributed discharge limiters relies critically on minimizing the delay time between HPM incidence and diffuse plasma creation. We present a range of pulsed plasma experiments conducted in neon, argon, helium, and mixtures of these gases, from 50-760 torr. Breakdown is achieved by illuminating a gas cell with a ~25kW, ~2 kV/cm, 800ns-long pulse as well as 41Hz pulse trains. Current results focus on preliminary experiments with metamaterial window coatings that indicate significant improvement opportunities for controlling breakdown thresholds and reducing breakdown delay. New results with gas mixtures in which observed breakdown occurs in <;100ns are also presented.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86963503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6633322
Seth A. Norberg, E. Johnsen, M. Kushner
Summary form only given. Reactive oxygen and nitrogen species (RONS) are desired in numerous applications from the destruction of harmful proteins and bacteria for sterilization in the medical field to taking advantage of the metastable characteristics of O2(1 Δ) to transfer energy to other species. Advances in atmospheric pressure plasma jets in recent years have shown the possibility of using this technology as a source of RONS. The plasma jets consist of small diameter tubes (a few mm) through which rare gas mixtures (e.g., He seeded with a few percent of O2) are flowed into room air. They are typically operated in a dielectric barrier discharge (DBD) configuration which produces an ionization wave (or plasma bullet) with repetition rates of many kHz to tens or hundreds of MHz. In this paper, we report on results of a computational investigation of the production of RONS from repetitively pulsed plasma jets at frequencies from many kHz to many MHz consisting of He/O2 mixtures discharged into ambient air. The computer model used in this study, nonPDPSIM, solves transport equations for charged and neutral species, Poisson's equation for the electric potential, the electron energy conservation equation for the electron temperature, and Navier-Stokes equations for the neutral gas flow. Rate coefficients and transport coefficients for the bulk plasma are obtained from local solutions of Boltzmann's equation for the electron energy distribution. The length of the interpulse period has significant effects on the density and distribution of the RONS in the effluent of the plasma jet. At high repetition rates (producing interpulse periods shorter than the gas clearing time), there is accumulation of RONS in the plume on a pulse-to-pulse basis, enabling further reactions between these species. The ionization wave of the following pulse samples the reactive environment produced by the previous pulse. At lower repetition rates, the interpulse periods are commensurate or longer than the clearing time of the gas through the device. In these cases, the ionization wave enters a more pristine and controllable environment.
{"title":"Reactive oxygen and nitrogen species (RONS) produced by repetitive pulses in atmospheric pressure plasma jets","authors":"Seth A. Norberg, E. Johnsen, M. Kushner","doi":"10.1109/PLASMA.2013.6633322","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6633322","url":null,"abstract":"Summary form only given. Reactive oxygen and nitrogen species (RONS) are desired in numerous applications from the destruction of harmful proteins and bacteria for sterilization in the medical field to taking advantage of the metastable characteristics of O2(1 Δ) to transfer energy to other species. Advances in atmospheric pressure plasma jets in recent years have shown the possibility of using this technology as a source of RONS. The plasma jets consist of small diameter tubes (a few mm) through which rare gas mixtures (e.g., He seeded with a few percent of O2) are flowed into room air. They are typically operated in a dielectric barrier discharge (DBD) configuration which produces an ionization wave (or plasma bullet) with repetition rates of many kHz to tens or hundreds of MHz. In this paper, we report on results of a computational investigation of the production of RONS from repetitively pulsed plasma jets at frequencies from many kHz to many MHz consisting of He/O2 mixtures discharged into ambient air. The computer model used in this study, nonPDPSIM, solves transport equations for charged and neutral species, Poisson's equation for the electric potential, the electron energy conservation equation for the electron temperature, and Navier-Stokes equations for the neutral gas flow. Rate coefficients and transport coefficients for the bulk plasma are obtained from local solutions of Boltzmann's equation for the electron energy distribution. The length of the interpulse period has significant effects on the density and distribution of the RONS in the effluent of the plasma jet. At high repetition rates (producing interpulse periods shorter than the gas clearing time), there is accumulation of RONS in the plume on a pulse-to-pulse basis, enabling further reactions between these species. The ionization wave of the following pulse samples the reactive environment produced by the previous pulse. At lower repetition rates, the interpulse periods are commensurate or longer than the clearing time of the gas through the device. In these cases, the ionization wave enters a more pristine and controllable environment.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90780585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6635026
D. Papp, V. Ivanov, R. Presura, A. Anderson, B. Talbot
Summary form only given. 2D resolved spectroscopy is an advanced plasma diagnostics tool, providing a method to determine the spatial dependence of plasma parameters (Te, ne). Convex crystal spectrometers are used to record X-ray spectra over wide energy (or wavelength) ranges. Strong source broadening is typical of such spectrometers, which can be dominant over other broadening mechanisms. The physical size of the source can reduce the resolving power (E/ΔE) of such spectrometer down to around 200. Spectra can be spatially resolved in a single dimension by using a slit to create an image of the source. In case of such spectra recorded by convex crystal spectrometers, it is often noted that the shape of the lines themselves, as recorded on a medium, resemble the shape of the plasma source. This provides some crude resolution perpendicular to the spectral line, allowing 2D spatially resolved spectroscopy of the X-ray source. This concept was applied to analyze the time-integrated spectra of Al-Mg wire array Z-pinch implosions on the Zebra generator. The K-shell emission as a function of plasma parameters (density, temperature and plasma thickness) was modeled by the PrismSPECT code. Treating intensity ratios as line ratios, 2D distribution of ne and Te in the pinch was determined.
{"title":"2D spatially resovled spectroscopy of hed plasmas using a single convex crystal","authors":"D. Papp, V. Ivanov, R. Presura, A. Anderson, B. Talbot","doi":"10.1109/PLASMA.2013.6635026","DOIUrl":"https://doi.org/10.1109/PLASMA.2013.6635026","url":null,"abstract":"Summary form only given. 2D resolved spectroscopy is an advanced plasma diagnostics tool, providing a method to determine the spatial dependence of plasma parameters (Te, ne). Convex crystal spectrometers are used to record X-ray spectra over wide energy (or wavelength) ranges. Strong source broadening is typical of such spectrometers, which can be dominant over other broadening mechanisms. The physical size of the source can reduce the resolving power (E/ΔE) of such spectrometer down to around 200. Spectra can be spatially resolved in a single dimension by using a slit to create an image of the source. In case of such spectra recorded by convex crystal spectrometers, it is often noted that the shape of the lines themselves, as recorded on a medium, resemble the shape of the plasma source. This provides some crude resolution perpendicular to the spectral line, allowing 2D spatially resolved spectroscopy of the X-ray source. This concept was applied to analyze the time-integrated spectra of Al-Mg wire array Z-pinch implosions on the Zebra generator. The K-shell emission as a function of plasma parameters (density, temperature and plasma thickness) was modeled by the PrismSPECT code. Treating intensity ratios as line ratios, 2D distribution of ne and Te in the pinch was determined.","PeriodicalId":6313,"journal":{"name":"2013 Abstracts IEEE International Conference on Plasma Science (ICOPS)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2013-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91138194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-06-16DOI: 10.1109/PLASMA.2013.6635176
Sehwan Jhin, Yunjung Kim, Won Young Lee, D. Jin, Hong-Keun Yu, Hyunchul Kim, J. Koo, G. Cho
Summary form only given. For flow in a pipe or tube, the Reynolds number (Re) is generally defined with fluid velocity, tube diameter, and kinematic viscosity. With a certain value of Re, the flow will become unstable and turbulent. This instability occurs with different fluids, usually when Re is over 2000. The laminar flow is stable if Re is less than 2000. In the interval between 2000 and 4000, laminar and turbulent flows are possible and are called "transition" flows, depending on other factors, such as pipe roughness and flow uniformity. In an atmospheric plasma jet of pencil type, a glass tube is used to insert the discharge gas. The property of plasma jet depends on the gas flow velocity which is given by the tube diameter and the volumetric gas flow rate. However, there exists an optimal flow velocity to obtain a stable plasma jet. The dependence of flow velocity on the instability of discharge plasma can be analyzed with Reynolds number which defines the stability of flow such as the stable laminar flow and the turbulent flow in hydro-kinetics. In this report the optimum flow velocity in a glass tube of plasma jet is investigated according to the stability of discharge plasma with the variation of Reynolds number. In the range of stable discharge where the laminar flow is sustained, the length of plasma jet column and plume is increased and the operational discharge voltage is decreased as the flow velocity is increased in the glass tube. However, if the gas flow velocity is increased to be over the critical value of turbulent flow, the length of plasma jet column as well as the plasma current varies unstably. In the conclusion the flow velocity has the limited value to keep the laminar flow inside the glass tube for the stable discharge of plasma jet.
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