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Sample records for coupled cf4 plasmas

  1. Simulation and Experimental Measurements of Inductively Coupled CF4 and CF4/Ar Plasmas

    NASA Technical Reports Server (NTRS)

    Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Arnold, James O. (Technical Monitor)

    2000-01-01

    The recently developed code SEMS (semiconductor equipment modeling software)is applied to the simulation of CF4 and CF4/Ar inductively coupled plasmas (ICP). This work builds upon the earlier nitrogen, transformer coupled plasma (TCP) SEMS research by demonstrating its accuracy for more complex reactive mixtures, moving closer to the realization of a virtual plasma reactor. Attention is given to the etching of and/or formation of carbonaceous films on the quartz dielectric window and diagnostic aperatures. The simulations are validated through comparisons with experimental measurements using FTIR (Fourier Transform Infrared) and UV absorption spectroscopy for CFx and SiFx neutral radicals, QMS (quadrupole mass spectrometry) for the ions, and Langmuir probe measurements of electron number density and temperature in an ICP GEC reference cell.

  2. Simulation and Experimental Measurements of Inductively Coupled CF4 and CF4/Ar Plasmas

    NASA Technical Reports Server (NTRS)

    Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Arnold, James O. (Technical Monitor)

    2000-01-01

    The recently developed code SEMS (semiconductor equipment modeling software)is applied to the simulation of CF4 and CF4/Ar inductively coupled plasmas (ICP). This work builds upon the earlier nitrogen, transformer coupled plasma (TCP) SEMS research by demonstrating its accuracy for more complex reactive mixtures, moving closer to the realization of a virtual plasma reactor. Attention is given to the etching of and/or formation of carbonaceous films on the quartz dielectric window and diagnostic aperatures. The simulations are validated through comparisons with experimental measurements using FTIR (Fourier Transform Infrared) and UV absorption spectroscopy for CFx and SiFx neutral radicals, QMS (quadrupole mass spectrometry) for the ions, and Langmuir probe measurements of electron number density and temperature in an ICP GEC reference cell.

  3. Mode transition in CF4 + Ar inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Gao, Fei; Zhao, Shu-Xia; Li, Xue-Chun; Wang, You-Nian

    2013-12-01

    The E to H mode transitions are studied by a hairpin probe and optical emission spectroscopy in inductively coupled CF4 + Ar plasmas. Electron density, optical emission intensity of Ar, and the voltage and current are measured during the E to H mode transitions. It is found that the electron density and plasma emission intensity increase continuously at low pressure during the E to H mode transition, while they jump up discontinuously at high pressure. Meanwhile, the transition threshold power and △P (the power interval between E and H mode) increase by increasing the pressure. When the ratio of CF4 increases, the E to H mode transition happens at higher applied power, and meanwhile, the △P also significantly increases. Besides, the effects of CF4 gas ratio on the plasma properties and the circuit electrical properties in both pure E and H modes were also investigated. The electron density and plasma emission intensity both decrease upon increasing the ratio of CF4 at the two modes, due to the stronger electrons loss scheme. The applied voltages at E and H modes both increase as increasing the CF4 gas ratio, however the applied current at two modes behave just oppositely with the gas ratio.

  4. Characterization of radical production mechanism in CHF3 and CF4 inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Yaping; Zhao, Shuxia; PSEG Team

    2015-09-01

    Inductively coupled fluorocarbon (fc) plasmas are widely used in Si /SiO2 etching industry as they provide active radicals which are reactive to the Si or SiO2 materials. It is well known that CHF3 plasma has relatively low density ratio of F vs. CFx radicals and hence high etching selectivity, as compared with the CF4 , due to the fact that one F is replaced by H in CHF3 molecules and H can abstract F from fluorocarbon radicals to form HF. However, for now, much elaborate details are still missed in the literature. Therefore in this work, a fluid model is used to characterize the radical production components in these two different fc plasmas. The fluid model includes continuity and energy equations for electrons, continuity and momentum equations for ions and continuity equations for radicals. An electromagnetic model is used to calculate the electric field which is generate by coupling coil current and Poisson equation is used to calculate the static field within the plasma. The model predicts the electron density, ion density and radical density of CHF3 plasma. For now the simulations of CF4 plasma are still under construction. We expect to compare the different radical production mechanisms in the CHF3 and CF4 plasma sources in new future.

  5. Langmuir Probe Measurements of Inductively Coupled Plasmas in CF4/Ar/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Meyyappan, M.; Sharma, S. P.

    2000-01-01

    Fluorocarbon gases, such as CF4, and their mixtures are widely used in contemporary low-pressure and high-density plasma processing techniques. In such plasmas Langmuir probe is one of the most commonly employed diagnostic techniques to obtain electron number density (ne), electron temperature (Te), electron energy distribution function (EEDF), mean electron energy (Ee), ion number density (ni), and plasma potential (Vp). In this paper we report probe data for planar inductively coupled plasmas in CF4/O2/Ar mixtures. By varying the relative concentrations in the mixture, radial profiles of ne, ni, Te, Ee, Vp, EEDF were measured in the mid-plane of the plasma at 10 mTorr and 20 mTorr of gas pressures, and 200 W and 300 W of RF powers. Data show that ne and ni decrease with increase of CF4 content and decrease of gas-pressure but they increase with increase of RF-power, whereas Vp increases with decrease of gas-pressure and remains independent of RF-power. However, they all peak at the center of the plasma and decrease towards the edge while Te follows the other way and increases a little with increase of power. The measured EEDFs exhibit Druyvesteyn-like distribution at all pressures and powers. Data are analyzed and will be presented.

  6. Metastable CF and CF2 molecules in CF4 inductively-coupled plasmas

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Corr, Cormac

    2006-02-01

    The radicals CF and CF2, which are important intermediates in fluorocarbon plasma chemistry, both have low-lying metastable levels (4CF at 3.54 eV and 3CF2 at 2.46 eV). Recent calculations (Rozum et al 2006 J. Phys. Chem. Ref. Data in press) indicate that electron-impact excitation of the ground-state radicals into these states could be fast. A recent study of inductively-coupled plasmas (ICP) in low-pressure CF4 (Booth et al 2005 Plasma Sources Sci. Technol. 14 273) indicated the presence of a fast electron-impact induced loss process for ground-state CF and CF2 molecules, which could be attributed to this process. In the current study 4CF and 3CF2 were detected in the afterglow of ICP in pure CF4 at pressures between 3 and 33 mTorr, from their weak forbidden optical emission back to their respective ground-states. From the lifetimes of these optical emission signals, determined as a function of gas pressure, the quenching coefficients at the chamber walls and the metastable destruction rates by gas-phase processes (giving unknown products) were estimated. Another prominent and long-lived feature of the afterglow is strong emission from the d state of C2 molecules: the emitting C2 molecules may be produced by chemiluminescent reactions or by excitation transfer from 3CF2.

  7. Numerical modeling of CF4 decomposition in low pressure inductively coupled plasma: influence of the O2 concentration

    NASA Astrophysics Data System (ADS)

    Setareh, Mahsa; Farnia, Morteza; Maghari, Ali; Bogaerts, Annemie

    2013-09-01

    Perfluorinated compounds (PFCs), which are stable and difficult to decompose, are widely utilized in microelectronic manufacturing. The global warming potential of PFCs is so high in comparison with CO2 that finding a solution for abating PFC emission is crucial. For this purpose, we performed a numerical simulation of the CF4 decomposition in an inductively coupled plasma reactor with radio frequency power supply, which is used in semiconductor chamber cleaning process. A zero dimensional modeling code Global_kin developed by Kushner is applied to model the reaction set of CF4/O2 in typical plasma reactor conditions, such as 2kW power with frequency of 4 MHz, a pressure of 600 mTorr, and a typical residence time of 0.25 s. The model predicts that the reaction products of the CF4 decomposition are mostly COF2, CO2 and CO. COF2 is a toxic compound, but it can be hydrolyzed easily into HF and CO2 using the scrubber in the reactor. By carefully altering the ratio between CF4/O2, the optimum ratio of the CF4/O2 gas mixture can be achieved, leading to more than 80% of CF4 decomposition. The numerical modeling results for CF4 decomposition are validated based on experimental data from literature.

  8. Langmuir Probe Measurements of Inductively Coupled Plasma in CF4/AR/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Cruden, Brett; Sharma, Surendra; Meyyappan, Meyya

    2001-01-01

    Inductively coupled plasmas of CF4:Ar:O2, which have been of importance to material processing, were studied in the GEC cell at 80:10:10, 60:20:20, and 40:30:30 mixture ratios. Radial distributions of plasma potential (V(sub p)), electron and ion number densities (n(sub e) and n(sub i)), electron temperature (T(sub e)), and electron energy distribution functions (EEDFs) were measured in the mid-plane of plasma across the electrodes in the pressure range of 10-50 mTorr, and RF power of 200 and 300 W. V(sub p), n(sub e) and n(sub i), which peak in the center of the plasma, increase with decrease of pressure. T(sub e) also increases with pressure but peaks toward the electrode edge. Both V(sub p) and T(sub e) remain nearly independent of RF power, whereas n(sub e) and n(sub i) increase with power. In all conditions the EEDFs exhibit non-Maxwellian shape and are more like Druyvesteyn form at higher energies. They exhibit a broad lip in the energy range 0-10 eV suggesting an electron loss mechanism, which could be due to via resonance electron attachment processes producing negative ions in this rich electronegative gas mixture. This behavior is more prominent towards the electrode edge.

  9. Langmuir Probe Measurements of Inductively Coupled Plasmas in CF4/Ar/O2 Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Cruden, Brett; Sharma, Surendra; Meyyappan, Meyya

    2001-01-01

    Inductively coupled plasmas of CF4:Ar:O2, which have been of importance to material processing, were studied in the GEC cell at 80:10:10, 60:20:20, and 40:30:30 mixture ratios. Radial distributions of plasma potential (V(sub p)), electron and ion number densities (n(sub e) and n(sub i), electron temperature (T(sub e)), and electron energy distribution functions (EEDFs) were measured in the mid-plane of plasma across the electrodes in the pressure range of 10-50 mTorr, and RF (radio frequency) power of 200 and 300 W. V(sub p), n(sub e) and n(sub i), which peak in the center of the plasma, increase with decrease of pressure. T(sub e) also increases with pressure but peaks toward the electrode edge. Both V(sub p) and T(sub e) remain nearly independent of RF power, whereas n(sub e) and n(sub i) increase with power. In all conditions the EEDFs exhibit non-Maxwellian shape and are more like Druyvesteyn form at higher energies. They exhibit a broad dip in the energy range 0-10 eV suggesting an electron loss mechanism, which could be due to via resonance electron attachment processes producing negative ions in this rich electronegative gas mixture. This behavior is more prominent towards the electrode edge.

  10. Langmuir Probe and Mass Spectroscopic Measurements in Inductively Coupled CF4 Plasmas

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Sharma, Surendra; Cruden, B. A.; Meyyappan, M.

    2001-01-01

    Abstract Electron and ion energy distribution functions and other plasma parameters such as plasma potential (V(sub p)) , electron temperature (T(sub e)), and electron and ion number densities (n (sub e) and n(sub i)) in low pressure CF4 plasmas have been measured. The experiments were conducted in a GEC cell using an inductively coupled plasma (ICP) device powered by a 13.56 MHz radio-frequency (rf) power source. The measurements were made at 300 W of input rf power at 10, 30 and 50 mTorr gas pressures. Langmuir probe measurements suggest that n(sub e), n(sub i) and V(sub p) remain constant over 60% of the central electrode area, beyond which they decrease. Within the limits of experimental error (+/- 0.25 eV), T(sub e) remains nearly constant over the electrode area. T(sub e) and V(sub p) increase with a decrease in pressure. n(sub e) and n(sub i) are not affected as significantly as T(sub e) or V(sub p) by variation in the gas pressure. The electron energy distribution function (EEDF) measurements indicate a highly non-Maxwellian plasma. CF3+ is the most dominant ion product of the plasma, followed by CF2+ and CF+. The concentrations of CF2+ and CF+ are much larger than that is possible from direct electron impact ionization of the parent gas. The cross-section data suggest that the direct electron impact ionization of fragment neutrals and negative ion production by electron attachment may be responsible for increase of the minor ions.

  11. Neutral Gas Temperature Estimates in an Inductively Coupled CF4 Plasma by Fitting Diatomic Emission Spectra

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.

    2001-01-01

    This work examines the accuracy of plasma neutral temperature estimates by fitting the rotational band envelope of different diatomic species in emission. Experiments are performed in an inductively coupled CF4 plasma generated in a Gaseous Electronics Conference reference cell. Visible and ultraviolet emission spectra are collected at a power of 300 W (approximately 0.7 W/cc) and pressure of 30 mtorr. The emission bands of several molecules (CF, CN, C2, CO, and SiF) are fit simultaneously for rotational and vibrational temperatures and compared. Four different rotational temperatures are obtained: 1250 K for CF and CN, 1600 K for CO, 1800 K for C2, and 2300 K for SiF. The vibrational temperatures obtained vary from 1750-5950 K, with the higher vibrational temperatures generally corresponding to the lower rotational temperatures. These results suggest that the different species have achieved different degrees of equilibration between the rotational and vibrational modes and may not be equilibrated with the translational temperatures. The different temperatures are also related to the likelihood that the species are produced by ion bombardment of the surface, with etch products like SiF, CO, and C2 having higher temperatures than species expected to have formed in the gas phase.

  12. High mass positive ions and molecules in capacitively-coupled radio-frequency CF4 plasmas

    NASA Astrophysics Data System (ADS)

    Schwarzenbach, W.; Cunge, G.; Booth, J. P.

    1999-06-01

    The positive ions and neutral radicals arriving at the earthed walls of a capacitively-coupled radio-frequency pure CF4 plasma were analyzed using a quadrupole mass spectrometer adapted for high masses. Experiments were performed at 50 and 200 mTorr, in an empty reactor and with Si and SiO2-coated Si substrates on the powered electrode. High mass ions and neutrals were detected, up to 500 and 300 amu, respectively. The abundance of high-mass species was greatest in the presence of silicon wafers and at higher pressure. The observed ion masses can be separated into distinct series, originating from different initial bases to which successive CF2 units have been added. We, therefore, propose that these high-mass species are the result of a gas phase polymerization process consisting of CF2 addition reactions, in agreement with a model proposed recently by our group. The influence of a silicon substrate derives primarily from the strong decrease that it induces in the concentration of F atoms, which otherwise limit the concentration of CF2 and of chain initiating species.

  13. Radical kinetics in an inductively-coupled plasma in CF4

    SciTech Connect

    Booth, J.P.; Abada, H.; Chabert, P.; Graves, D.B.

    2004-12-01

    Radiofrequency discharges in low pressure fluorocarbon gases are used for anisotropic and selective etching of dielectric materials (SiO2 and derivatives), a key step in the manufacture of integrated circuits. Plasmas in these gases are capable not only of etching, but also of depositing fluorocarbon films, depending on a number of factors including the ion bombardment energy, the gas composition and the surface temperature: this behavior is indeed responsible for etch selectivity between materials and plays a role in achieving the desired etched feature profiles. Free radical species, such as CFx and fluorine atoms, play important but complex roles in these processes. We have used laser-induced fluorescence (LIF), with time and space resolution in pulsed plasmas, to elucidate the kinetics of CF and CF2 radicals, elucidating their creation, destruction and transport mechanisms within the reactor. Whereas more complex gas mixtures are used in industrial processes, study of the relatively simple system of a pure CF4 plasma is more appropriate for the study of mechanisms. Previously the technique was applied to the study of single-frequency capacitively-coupled 'reactive ion etching' reactors, where the substrate (placed on the powered electrode) is always bombarded with high-energy CF{sub x}{sup +} ions. In this case it was found that the major source of CFx free radicals was neutralization, dissociation and backscattering of these incident ions, rather than direct dissociation of the feedstock gas. Subsequently, an inductively-coupled plasma (ICP) in pure CF4 was studied. This system has a higher plasma density, leading to higher gas dissociation, whereas the energy of ions striking the reactor surfaces is much lower (in the absence of additional RF biasing). The LIF technique also allows the gas temperature to be measured with good spatial and temporal resolution. This showed large gas temperature gradients within the ICP reactor, which must be taken into account

  14. Ion Energy and Ion Flux Distributions of CF4/Ar/O2 Inductively Coupled Plasmas in a GEC Cell

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Cruden, Brett; Sharma, Surendra; Meyyappan, Meyya

    2001-01-01

    Knowledge of ion kinetics in plasma processing gas mixtures, such as CF4:Ar:O2, is important for understanding plasma assisted etching and deposition of materials. Ion energies and ion fluxes were measured in this mixture for 80:10:10, 60:20:20, and 40:30:30 mixture ratios in the pressure range of 10-50 mTorr, and at 200 and 300 W of RF power. Ions from plasma, sampled through a 10 micron orifice in the center of the lower plane electrode, were energy and mass analyzed by a combination of electrostatic energy and quadrupole mass filters. CFx(+) (x = 1 - 3), F2(+), F(+), C(+) from CF4, Ar(+) from Ar, and O2(+) and O(+) from O2, and by-product ions SiFx(+)(x = 1 - 3) from etching of quartz coupling window, COFx(+)(x = 1 - 3), CO(+), CO2(+), and OF(+) were detected. In all conditions ion flux decreases with increase of pressure but increase with increase of RF power. Ar(+) signal decreases with increase of pressure while CF3(+), which is the dominant ion at all conditions, increases with increase in pressure. The loss mechanism for Ar(+) and increase of CF3(+) is due to large cross section for Ar(+) + CF4 yields Ar + CF3(+) + F. Ion energies, which range from 15-25 eV depending on plasma operating conditions, are nearly Gaussian. By-product ion signals are higher at lower pressures indicating stronger plasma interaction with quartz window.

  15. Measurements of Ion Energy and Ion Flux Distributions in Inductively Coupled Plasmas in CF4/O2/Ar Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Kim, J. S.; Cappelli, M. A.; Sharma, Surendra; Partridge, Harry (Technical Monitor)

    1999-01-01

    We report mass spectrometric studies of energy distributions and absolute concentrations of ions generated in CF4/O2/Ar inductively coupled rf plasmas. The ions were collected through a 100 mm orifice in the grounded and water cooled lower electrode in a GEC cell configuration. The measurements were made at gas pressures in the 10-50 mTorr range and rf coil power in the 100-300 W range. The observed ions are CF3(+), CF2(+), CF(+), C(+), F(+), COF(+), CO(+), O2(+), and O(+). The relative abundance of these ions varies with pressure and rf power. The energy distribution and absolute concentrations are correlated with electron number density and floating plasma potential measured by a compensated Langmuir probe.

  16. Measurements of Ion Energy and Ion Flux Distributions in Inductively Coupled Plasmas in CF4/O2/Ar Mixtures

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Kim, J. S.; Cappelli, M. A.; Sharma, Surendra; Partridge, Harry (Technical Monitor)

    1999-01-01

    We report mass spectrometric studies of energy distributions and absolute concentrations of ions generated in CF4/O2/Ar inductively coupled rf plasmas. The ions were collected through a 100 mm orifice in the grounded and water cooled lower electrode in a GEC cell configuration. The measurements were made at gas pressures in the 10-50 mTorr range and rf coil power in the 100-300 W range. The observed ions are CF3(+), CF2(+), CF(+), C(+), F(+), COF(+), CO(+), O2(+), and O(+). The relative abundance of these ions varies with pressure and rf power. The energy distribution and absolute concentrations are correlated with electron number density and floating plasma potential measured by a compensated Langmuir probe.

  17. Application of Si and SiO2 Etching Mechanisms in CF4/C4F8/Ar Inductively Coupled Plasmas for Nanoscale Patterns.

    PubMed

    Lee, Junmyung; Efremov, Alexander; Yeom, Geun Young; Lim, Nomin; Kwon, Kwang-Ho

    2015-10-01

    An investigation of the etching characteristics and mechanism for both Si and SiO2 in CF4/C4F8/Ar inductively coupled plasmas under a constant gas pressure (4 mTorr), total gas flow rate (40 sccm), input power (800 W), and bias power (150 W) was performed. It was found that the variations in the CF4/C4F8 mixing ratio in the range of 0-50% at a constant Ar fraction of 50% resulted in slightly non-monotonic Si and SiO2 etching rates in CF4-rich plasmas and greatly decreasing etching rates in C4F8-rich plasmas. The zero-dimensional plasma model, Langmuir probe diagnostics, and optical emission spectroscopy provided information regarding the formation-decay kinetics for the plasma active species, along with their densities and fluxes. The model-based analysis of the etching kinetics indicated that the non-monotonic etching rates were caused not by the similar behavior of the fluorine atom density but rather by the opposite changes of the fluorine atom flux and ion energy flux. It was also determined that the great decrease in both the Si and SiO2 etching rates during the transition from the CF4/Ar to C4F8/Ar gas system was due to the deposition of the fluorocarbon polymer film.

  18. Comparison of vacuum ultra-violet emission of Ar/CF4 and Ar/CF3I capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Zotovich, A.; Proshina, O.; el Otell, Z.; Lopaev, D.; Rakhimova, T.; Rakhimov, A.; de Marneffe, J.-F.; Baklanov, M. R.

    2016-10-01

    Spectra in the vacuum-ultra violet range (VUV, 30 nm-200 nm) as well as in the ultra-violet(UV) and visible ranges (UV+vis, 200 nm-800 nm) were measured from Ar/CF3I and Ar/CF4 discharges. The discharges were generated in an industrial 300 mm capacitively coupled plasma source with 27 MHz radio-frequency power. It was seen that the measured spectra were strongly modified. This is mainly due to absorption, especially by CF3I, and Ar self-trapping along the line of sight, towards the detector and in the plasma itself. The estimated unabsorbed VUV spectra were revealed from the spectra of mixtures with low fluorocarbon gas content by means of normalization with unabsorbed I* emission, at 206 nm, and CF2\\ast band (1B1(0,v‧,0){{\\to}1} A1(0,{{\\text{v}}\\prime \\prime} ,0)) emission between 230 nm and 430 nm. Absolute fluences of UV CF2\\ast emission were derived using hybrid 1-dimensional (1D) particle-in-cell (PIC) Monte-Carlo (MC) model calculations. Absolute calibration of the VUV emission was performed using these calculated values from the model, which has never been done previously for real etch conditions in an industrial chamber. It was seen that the argon resonant lines play a significant role in the VUV spectra. These lines are dominant in the case of etching recipes close to the standard ones. The restored unabsorbed spectra confirm that replacement of conventional CF4 etchant gas with CF3I in low-k etching recipes leads to an increase in the overall VUV emission intensity. However, emission from Ar exhibited the most intense peaks. Damage to low-k SiCOH glasses by the estimated VUV was calculated for blanket samples with pristine k-value of 2.2. The calculations were then compared with Fourier transform infrared (FTIR) data for samples exposed to the similar experimental conditions in the same reactor. It was shown that Ar emission plays the most significant role in VUV-induced damage.

  19. Absolute CF2 density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF4/Ar plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Yao; Xu, Yong; Liu, Yong-Xin; Peng, Fei; Gong, Fa-Ping; Li, Xiao-Song; Zhu, Ai-Min; Wang, You-Nian

    2014-10-01

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF2 radical density in dual-frequency capacitively coupled CF4/Ar plasmas, using the CF2 A ˜ 1 B 1 ← X ˜ 1 A 1 system of absorption spectrum. The rotational temperature of ground state CF2 and excited state CF was also estimated by using A ˜ 1 B 1 ← X ˜ 1 A 1 system and B 2 Δ - X 2 Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar*(3P2) and Ar*(3P0) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100 K higher than those of ground state CF2, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF2 density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF2 radical and the gas heating mechanisms have also been discussed.

  20. Time resolved QCLAS measurements in pulsed cc-rf CF4/H2 plasmas

    NASA Astrophysics Data System (ADS)

    Stepanov, S.; Welzel, S.; Röpcke, J.; Meichsner, J.

    2009-03-01

    Fluorocarbon containing capacitively coupled radio frequency (cc-rf) plasmas are widely used in technical applications and as model systems for fundamental investigations of complex plasmas. Absorption spectroscopy based on pulsed quantum cascade lasers (QCL) was applied in the mid-IR spectral range of 1269-1275 cm-1. Absolute densities of the precursor molecule CF4 and of the stable product C3F8 were measured with a time resolution of up to 1 ms in pulsed CF4/H2 asymmetrical cc-rf (13.56 MHz) discharges. For this purpose both the non-negligible temperature dependence of the absorption coefficients and the interference of the absorption features of CF4 and C3F8 had to be taken into account in the target spectral range. Therefore, at two different spectral positions composite absorption spectra were acquired under the same plasma conditions in order to discriminate between CF4 and C3F8 contributions. A total consumption of~ 12 % was observed for CF4 during a 1 s plasma pulse, whereas C3F8 appeared to be produced mainly from amorphous fluorocarbon layers deposited at the reactor walls. A gas temperature increase by ~ 100 K in the plasma pulse was estimated from the measurements. Additionally, not yet identified unresolved absorption (potentially from the excited CF4 molecule) was found during the àon-phase'.

  1. Plasma parameters and active species kinetics in CF4/O2/Ar gas mixture: effects of CF4/O2 and O2/Ar mixing ratios

    NASA Astrophysics Data System (ADS)

    Lee, Junmyung; Kwon, Kwang-Ho; Efremov, A.

    2016-12-01

    The effects of both CF4/O2 and O2/Ar mixing ratios in three-component CF4/O2/Ar mixture on plasma parameters, densities and fluxes of active species determining the dry etching kinetics were analyzed. The investigation combined plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling. It was found that the substitution of CF4 for O2 at constant fraction of Ar in a feed gas produces the non-monotonic change in F atom density, as it was repeatedly reported for the binary CF4/O2 gas mixtures. At the same time, the substitution of Ar for O2 at constant fraction of CF4 results in the monotonic increase in F atom density toward more oxygenated plasmas. The natures of these phenomena as well as theirs possible impacts on the etching/polymerization kinetics were discussed in details.

  2. Super-hydrophobicity and oleophobicity of silicone rubber modified by CF 4 radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Gao, Song-Hua; Gao, Li-Hua; Zhou, Ke-Sheng

    2011-03-01

    Owing to excellent electric properties, silicone rubber (SIR) has been widely employed in outdoor insulator. For further improving its hydrophobicity and service life, the SIR samples are treated by CF 4 radio frequency (RF) capacitively coupled plasma. The hydrophobic and oleophobic properties are characterized by static contact angle method. The surface morphology of modified SIR is observed by atom force microscope (AFM). X-ray photoelectron spectroscopy (XPS) is used to test the variation of the functional groups on the SIR surface due to the treatment by CF 4 plasma. The results indicate that the static contact angle of SIR surface is improved from 100.7° to 150.2° via the CF 4 plasma modification, and the super-hydrophobic surface of modified SIR, which the corresponding static contact angle is 150.2°, appears at RF power of 200 W for a 5 min treatment time. It is found that the super-hydrophobic surface ascribes to the coaction of the increase of roughness created by the ablation action and the formation of [-SiF x(CH 3) 2- x-O-] n ( x = 1, 2) structure produced by F atoms replacement methyl groups reaction, more importantly, the formation of [-SiF 2-O-] n structure is the major factor for super-hydrophobic surface, and it is different from the previous studies, which proposed the fluorocarbon species such as C-F, C-F 2, C-F 3, CF-CF n, and C-CF n, were largely introduced to the polymer surface and responsible for the formation of low surface energy.

  3. Abatement of SF6 and CF4 using an enhanced kerosene microwave plasma burner

    NASA Astrophysics Data System (ADS)

    Hun Shin, Dong; Cheol Hong, Yong; Cheon Cho, Soon; Sup Uhm, Han

    2006-11-01

    A kerosene microwave plasma burner was presented as a tool for abatement of SF6 and CF4 gases, which cause global warming. The plasma burner operates by injecting kerosene as a liquid hydrocarbon fuel into a microwave plasma torch and by mixing the resultant gaseous hydrogen and carbon compounds with air or oxygen (O2) gas. The abatement of SF6 and CF4, by making use of the kerosene plasma burner, was conducted in terms of nitrogen (N2) flow rates. The destruction and removal efficiency of the burner were achieved up to 99.9999% for 0.1 liters per minute (lpm) SF6 in 120lpm N2 and 99.3% for 0.05lpm CF4 in 60lpm N2, revealing that the microwave plasma burner can effectively eliminate perfluorocompounds emitted from the semiconductor industries.

  4. Comparative study of CF4- and CHF3-based plasmas for dry etching applications

    NASA Astrophysics Data System (ADS)

    Efremov, A.; Kwon, K.-H.; Morgunov, A.; Shabadarova, D.

    2016-12-01

    The influence of O2/Ar mixing ratio on plasma characteristics, densities and fluxes of active species determining the dry etching kinetics in both CF4/O2/Ar and CHF3/O2/Ar plasmas was studied. The investigation combined plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling. It was found that the substitution of O2 for Ar at constant fraction of CF4 or CHF3 in a feed gas noticeably changes electron temperature and electron density, but does not result in the non-monotonic behavior of F atom density. The differences between two gas systems were discussed in details from the point of view of plasma chemistry.

  5. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization

    PubMed Central

    Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

    2017-01-01

    The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions. PMID:28904833

  6. Fluorination of vertically aligned carbon nanotubes: from CF4 plasma chemistry to surface functionalization.

    PubMed

    Struzzi, Claudia; Scardamaglia, Mattia; Colomer, Jean-François; Verdini, Alberto; Floreano, Luca; Snyders, Rony; Bittencourt, Carla

    2017-01-01

    The surface chemistry of plasma fluorinated vertically aligned carbon nanotubes (vCNT) is correlated to the CF4 plasma chemical composition. The results obtained via FTIR and mass spectrometry are combined with the XPS and Raman analysis of the sample surface showing the dependence on different plasma parameters (power, time and distance from the plasma region) on the resulting fluorination. Photoemission and absorption spectroscopies are used to investigate the evolution of the electronic properties as a function of the fluorine content at the vCNT surface. The samples suffer a limited ageing effect, with a small loss of fluorine functionalities after two weeks in ambient conditions.

  7. Vacuum ultra-violet emission of CF4 and CF3I containing plasmas and Their effect on low-k materials

    NASA Astrophysics Data System (ADS)

    el Otell, Z.; Šamara, V.; Zotovich, A.; Hansen, T.; de Marneffe, J.-F.; Baklanov, M. R.

    2015-10-01

    CF3I was suggested as a replacement of CF4 gas to decrease the plasma-induced damage (PID) on low-k dielectrics during etching. This proposal is investigated by means of plasma emission measurements and material characterisation. The experiments were conducted in a 300 mm capacitively coupled plasma source. The vacuum ultraviolet (VUV, 30≤slant λ ≤slant 220 nm) plasma emission was measured for discharges generated in a pure or a mixture of argon, CF4 and/or CF3I, since VUV plays a major role in PID. However, CF3I containing discharges were found to have a stronger emission than CF4 in the VUV range. Nevertheless, Fourier transform infra-red spectroscopy and κ-value measurements showed that there is almost no difference between the damage caused by CF3I or CF4 containing plasmas, while etching in a capacitively coupled plasma source. It is proposed that the damage caused by CF3I with lower F*-density but higher VUV-photon flux is similar to the damage caused by CF4, with higher F*-density but lower VUV-photon flux.

  8. Multifold study of volume plasma chemistry in Ar/CF4 and Ar/CHF3 CCP discharges

    NASA Astrophysics Data System (ADS)

    Proshina, O. V.; Rakhimova, T. V.; Zotovich, A. I.; Lopaev, D. V.; Zyryanov, S. M.; Rakhimov, A. T.

    2017-07-01

    Low-pressure RF plasma in fluorohydrocarbon gas mixtures is widely used in modern microelectronics, e.g. in the etching of materials with a low dielectric constant (low-k) materials). The multifold experimental and theoretical study of a radio frequency capacitively coupled plasma at 81 MHz in Ar/CF4/CHF3 has been carried out at 50 mTorr and 150 mTorr gas pressures. A wide set of experimental diagnostics together with hybrid PIC MC model calculations were applied to a detailed study of the plasmas. Measurements of the F atoms, HF molecules and CF x radicals, electron density, electronegativity and positive ion composition were performed. Absolutely calibrated VUV spectrometry was carried out to measure the VUV photon fluence towards the electrode. This combined experimental and model approach allowed us to establish the fundamental mechanisms of the charged and neutral species elementary reactions. Dissociative charge transfer reactions and fluoride transfer reactions influence the main ion (CF{}3+, CHF{}2+) composition in Ar/CF4/CHF3 plasma a lot. The mechanisms of heavy ion formation in Ar/CHF3 are also discussed. The important role of additional attachment mechanisms (besides dissociative attachment to the feedstock gases, CF4, CHF3) was analyzed. The catalytic chain mechanism, including the HF molecules, which defines the CF x kinetics in Ar/CHF3 plasma, was validated. This multifold approach enabled us to determine the complicated plasma chemical composition of the active species as well as the fluxes of VUV photons at the surface of the processed material, and is a result that is important for understanding low-k damage.

  9. Investigation of the atomic emission spectroscopy of F atoms and CF2 molecules in CF4 plasma processing

    NASA Astrophysics Data System (ADS)

    Jin, Huiliang; Li, Jie; Tang, Caixue; Deng, Wenhui; Chen, Xianhua

    2016-10-01

    The surface chemistry reaction involved in the processing of Atmospheric Pressure Plasma Jet (APPJ) produced from CF4 precursor has been explored. The atomic emission spectroscopy of F atoms and CF2 molecules was investigated as they contribute to substrate etching and FC film formation during APPJ processing. Optical emission spectroscopy (OES) spectra were acquired for CF4 plasma, relative concentrations of excited state species of F atoms and CF2 molecules were also dependent upon plasma parameters. The densities of F atoms increased dramatically with increasing applied RF power, whereas CF2 molecules decreased monotonically over the same power range, the subsequent electron impacted decomposition of plasma species after CF4 precursor fragmentation. The spectrum of the F atoms and CF2 molecules fallowed the same tendency with the increasing concentration of gas CF4, reaching the maximum at the 20sccm and 15sccm respectively, and then the emission intensity of reactive atoms decreased with more CF4 molecules participating. Addition certain amount O2 into CF4 plasma resulted in promoting CF4 dissociation, O2 can easily react with the dissociation product of CF2 molecules, which inhibit the compound of the F atoms, so with the increasing concentration of O2, the concentration of the CF2 molecules decreased and the emission intensities of F atoms showed the maximum at the O2/CF4 ratio of 20%. These results have led to the development of a scheme that illustrates the mechanisms of surface chemistry reaction and the affection of plasma parameters in CF4 plasma systems with respect to F and CF2 gas-phase species.

  10. CF and CF2 actinometry in a CF4/Ar plasma

    NASA Astrophysics Data System (ADS)

    Kiss, L. D. B.; Nicolai, J.-P.; Conner, W. T.; Sawin, H. H.

    1992-04-01

    Relative ground state CF and CF2 concentrations have been measured in a 13.56-MHz rf CF4/Ar discharge using both laser-induced fluorescence (LIF) and actinometric techniques to assess the validity of actinometry for CF and CF2 over a limited parameter space of pressure and power. Relative measurements of the CF ( A2Σ - X2Π) system and the CF2 ( A1B1 - X1A1) system were made by LIF. Actinometric values were calculated from relative measures of the plasma-induced emission (PIE) intensity of the CF* ( B2Δ- X2Π) at 202.4 nm, CF2* ( A1B1 - X1A1) at 251.9 nm, and Ar* [4s'(1/2)°-4p'(1/2)] at 750.4 nm. Both LIF and PIE signals were spatially averaged over the bulk of the plasma. Steady-state actinometric and LIF measurements were compared for CF4/5% Ar discharges at pressures in the range of 500 to 1000 mTorr and nominal powers in the range of 20 to 100 W. Dynamic actinometric and LIF measurements of CF were made by modulating the discharge power and monitoring the CF transient at one set of conditions, 500-mTorr pressure and 70-W nominal power. Our results indicate that actinometric measurements of CF and CF2 correlate well with relative CF and CF2 LIF measurements under the studied conditions.

  11. Determining the Concentrations and Temperatures of Products in a CF_4/CHF_3/N_2 Plasma via Submillimeter Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Helal, Yaser H.; Neese, Christopher F.; De Lucia, Frank C.; Ewing, Paul R.; Agarwal, Ankur; Craver, Barry; Stout, Phillip J.; Armacost, Michael D.

    2017-06-01

    Plasmas used for the manufacturing of semiconductor devices are similar in pressure and temperature to those used in the laboratory for the study of astrophysical species in the submillimeter (SMM) spectral region. The methods and technology developed in the SMM for these laboratory studies are directly applicable for diagnostic measurements in the semiconductor manufacturing industry. Many of the molecular neutrals, radicals, and ions present in processing plasmas have been studied and their spectra have been cataloged or are in the literature. In this work, a continuous wave, intensity calibrated SMM absorption spectrometer was developed as a remote sensor of gas and plasma species. A major advantage of intensity calibrated rotational absorption spectroscopy is its ability to determine absolute concentrations and temperatures of plasma species from first principles without altering the plasma environment. An important part of this work was the design of the optical components which couple 500-750 GHz radiation through a commercial inductively coupled plasma chamber. The measurement of transmission spectra was simultaneously fit for background and absorption signal. The measured absorption was used to calculate absolute densities and temperatures of polar species. Measurements for CHF_3, CF_2, FCN, HCN, and CN made in a CF_4/CHF_3/N_2 plasma will be presented. Temperature equilibrium among species will be shown and the common temperature is leveraged to obtain accurate density measurements for simultaneously observed species. The densities and temperatures of plasma species are studied as a function of plasma parameters, including flow rate, pressure, and discharge power.

  12. CF4 plasma treatment-assisted inkjet printing for color pixel flexible display

    NASA Astrophysics Data System (ADS)

    Tortissier, G.; Ginet, P.; Daunay, B.; Jalabert, L.; Lambert, P.; Kim, B.; Fujita, H.; Toshiyoshi, H.

    2011-10-01

    In this paper we report a MEMS flexible display device based on the color filter Fabry-Perot interferometer and fabricated on a transparent and flexible polyethylene naphthalate substrate. Targeting easy processing, fast evolution and reduced fabrication steps, inkjet printing is selected as a promising technology. CF4 plasma surface treatment parameters' influence has been investigated through a design of experiment protocol. Important contact angle increase has led to pattern resolution between 50 and 100 µm depending on solutions and substrate nature. Finally, the designed device presents three primary color pixels with satisfying color purity (CIE 1931 chromaticity diagram—red: x = 0.52, y = 0.36; blue: x = 0.13, y = 0.20; green: x = 0.25, y = 0.57).

  13. Switchable hydrophobic/hydrophilic surface of electrospun poly (L-lactide) membranes obtained by CF4 microwave plasma treatment

    NASA Astrophysics Data System (ADS)

    Yue, Mengyao; Zhou, Baoming; Jiao, Kunyan; Qian, Xiaoming; Xu, Zhiwei; Teng, Kunyue; Zhao, Lihuan; Wang, Jiajun; Jiao, Yanan

    2015-02-01

    A switchable surface that promotes either hydrophobic or hydrophilic wettability of poly (L-lactide) (PLLA) microfibrous membranes is obtained by CF4 microwave plasma treatment in this paper. The results indicated that both etching and grafting process occurred during the CF4 plasma treatment and these two factors synergistically affected the final surface wettability of PLLA membranes. When plasma treatment was taken under a relatively low power, the surface wettability of PLLA membranes turned from hydrophobic to hydrophilic. Especially when CF4 plasma treatment was taken under 100 W for 10 min and 150 W for 5 min, the water contact angle sharply decreased from 116 ± 3.0° to ∼0°. According to Field-emission scanning electron microscopy (FESEM) results, the PLLA fibers were notably etched by CF4 plasma treatment. Combined with the X-ray photoelectron spectroscopy (XPS) measurements, only a few fluorine-containing groups were grafted onto the surface, so the etching effect directly affected the surface wettability of PLLA membranes in low plasma power condition. However, with the plasma power increasing to 200 W, the PLLA membrane surface turned to hydrophobic again. In contrast, the morphology changes of PLLA fiber surfaces were not obvious while a large number of fluorine-containing groups grafted onto the surface. So the grafting effect gradually became the major factor for the final surface wettability.

  14. Heterogeneous processes in CF4/O2 plasmas probed using laser-induced fluorescence of CF2

    NASA Astrophysics Data System (ADS)

    Hansen, S. G.; Luckman, G.; Nieman, George C.; Colson, Steven D.

    1990-09-01

    Laser-induced fluorescence of CF2 is used to monitor heterogeneous processes in ≊300 mTorr CF4/O2 plasmas. CF2 is rapidly removed at fluorinated copper and silver surfaces in 13.56-MHz rf discharges as judged by a distinct dip in its spatial distribution. These metals, when employed as etch masks, are known to accelerate plasma etching of silicon, and the present results suggest catalytic dehalogenation of CF2 is involved in this process. In contrast, aluminum and silicon dioxide exhibit negligible reactivity with CF2, which suggests that aluminum masks will not appreciably accelerate silicon etching and that ground state CF2 does not efficiently etch silicon dioxide. Measurement of CF2 decay in a pulsed discharge coupled with direct laser sputtering of metal into the gas phase indicates the interaction between CF2 and the active metals is purely heterogeneous. Aluminum does, however, exhibit homogeneous reactivity with CF2. Redistribution of active metal by plasma sputtering readily occurs; silicon etch rates may also be enhanced by the metal's presence on the silicon surface. Polymers contribute CF2 to the plasma as they etch. The observation of an induction period suggests fluorination of the polymer surface is the first step in its degradation. Polymeric etch masks can therefore depress the silicon etch rate by removal of F atoms, the primary etchants.

  15. Tailoring the chemical composition and dispersion behavior of fluorinated graphene oxide via CF4 plasma

    NASA Astrophysics Data System (ADS)

    Zhou, Baoming; Qian, Xiaoming; Li, Mingming; Ma, Jilan; Liu, Liangsen; Hu, Chuansheng; Xu, Zhiwei; Jiao, Xiaoning

    2015-03-01

    Grafting fluorine onto graphene oxide (GO) by CF4 plasma treatment was investigated in this study. An easy, low-cost, and effective synthesis of the high-dispersive fluorinated GO (FGO) with tunable atomic ratio of F/O ( R F/O) has been realized and the R F/O can be readily manipulated just by adjusting the reaction time. The influence of plasma treatment time on the microstructure, morphology, and dispersion of graphene nanosheets was systematically analyzed. X-ray photoelectron spectroscopy analysis confirmed that fluorine has been grafted onto graphene, and the R F/O was gradually increased to 3.54 for the FGO treated for 20 min. Morphology investigation indicated that etching on the edge of GO occurred during the fluorination. The dispersion performance of FGO in water reduced continuously, which in N, N-dimethylacetamide (DMAc) increased firstly and then decreased with the increase in plasma time. The zeta potentials of FGO in DMAc reached the lowest at -28.6 mV when GO was treated for 10 min. The dispersion of FGO in water should be attributed to the decrease of C-O group, while there was a same variation trend of FGO zeta potential in DMAc as the value of C-F content, regardless of R F/O, CF2 group content and CF3 group content. The GO film was super-hydrophilic and the film of FGO treated for 20 min was found to be neither hydrophilic nor hydrophobic.

  16. Hydrophobization of polymer particles by tetrafluoromethane (CF4) plasma irradiation using a barrel-plasma-treatment system

    NASA Astrophysics Data System (ADS)

    Matsubara, Keisuke; Danno, Masato; Inoue, Mitsuhiro; Nishizawa, Hideki; Honda, Yuji; Abe, Takayuki

    2013-11-01

    In this study, tetrafluoromethane (CF4) plasma-treatments of polymethylmethacrylate (PMMA) powder were performed using a polygonal barrel-plasma-treatment system to improve the PMMA's hydrophobicity. Characterization of the treated samples showed that the PMMA particle surfaces were fluorinated by the CF4 treatment. The smooth surfaces of the particles changed into nano-sized worm-like structures after the plasma-treatment. The hydrophobicity of the treated PMMA samples was superior to that of the untreated samples. It was noted that the hydrophobicity of the treated samples and the surface fluorination level depended on the plasma-treatment time and radiofrequency (RF) power; high RF power increased the sample temperature, which in turn decreased the hydrophobicity of the treated samples and the surface fluorination because of the thermal decomposition of PMMA. The water-repellent effects were evaluated by using paper towels to show the application of the plasma-treated PMMA particles, with the result that the paper towel coated with the treated sample was highly water-repellent.

  17. Low-damage plasma etching of porous low-k films in CF3Br and CF4 plasmas under low-temperature conditions

    NASA Astrophysics Data System (ADS)

    Miakonkikh, A.; Clemente, I.; Vishnevskiy, A.; Rudenko, K.; Baklanov, M.

    2016-12-01

    Low temperature etching of organosilicate low-k dielectrics in CF3Br and CF4 plasmas is studied. Chemical composition if pristine film and etched were measured by FTIR. Decrease in plasma-induced damage under low-temperature conditions is observed. It is shown that the plasma damage reduction is related to accumulation of reaction products. The reaction products could be removed by thermal bake. In the case of CF4 plasma, the thickness of CFx polymer increases with the temperature reduction. This polymer layer leads to strong decrease of diffusion rate of fluorine atoms and as a consequence to reduction of plasma-induced damage (PID). Bromine containing reaction products are less efficient for low-k surface protection against the plasma damage.

  18. ICP Reactor Modeling: CF4 Discharge

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    1999-01-01

    Inductively coupled plasma (ICP) reactors are widely used now for etching and deposition applications due to their simpler design compared to other high density sources. Plasma reactor modeling has been playing an important role since it can, in principle, reduce the number of trial and error iterations in the design process and provide valuable understanding of mechanisms. Fluorocarbon precursors have been the choice for oxide etching. We have data available on CF4 from our laboratory. These are current voltage characteristics, La.ngmuir probe data, UV-absorption, and mass spectrometry measurements in a GEC-ICP reactor. We have developed a comprehensive model for ICP reactors which couples plasma generation and transport and neutral species dynamics with the gas flow equations. The model has been verified by comparison with experimental results for a nitrogen discharge in an ICP reactor. In the present work, the model has been applied to CF4 discharge and compared to available experimental data.

  19. Effects of substrate bias power on the surface of ITO electrodes during O2/CF4 plasma treatment and the resulting performance of organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Han, D. M.; Lee, J. H.; Jeong, K. H.; Lee, J. G.

    2010-08-01

    During surface treatment using O2/CF4 plasma chemistry, the bias power applied to the indium-tin-oxide(ITO) substrate significantly degrades the electrical and optical performance of the organic light emitting diode (OLED) formed on the ITO electrode as a result of the formation of CFx polymer, In-Sn-F compounds, and structural defects. Application of bias power to the substrate effectively increases the sheath potential over the substrate and thus the flux of CFx + ion created in the O2/CF4 plasma, which leads to the production of CFx polymers as well as structural defects.

  20. Surface modification of epoxy resin using He/CF4 atmospheric pressure plasma jet for flashover withstanding characteristics improvement in vacuum

    NASA Astrophysics Data System (ADS)

    Chen, Sile; Wang, Shuai; Wang, Yibo; Guo, Baohong; Li, Guoqiang; Chang, Zhengshi; Zhang, Guan-Jun

    2017-08-01

    For enhancing the surface electric withstanding strength of insulating materials, epoxy resin (EP) samples are treated by atmospheric pressure plasma jet (APPJ) with different time interval from 0 to 300s. Helium (He) and tetrafluoromethane (CF4) mixtures are used as working gases with the concentration of CF4 ranging 0%-5%, and when CF4 is ∼3%, the APPJ exhibits an optimal steady state. The flashover withstanding characteristics of modified EP in vacuum are greatly improved under appropriate APPJ treatment conditions. The surface properties of EP samples are evaluated by surface roughness, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle. It is considered that both physical and chemical effects lead to the enhancement of flashover strength. The physical effect is reflected in the increase of surface roughness, while the chemical effect is reflected in the graft of fluorine groups.

  1. Radio-frequency plasma functionalization of carbon nanotubes surface O2, NH3, and CF4 treatments

    NASA Astrophysics Data System (ADS)

    Felten, A.; Bittencourt, C.; Pireaux, J. J.; van Lier, G.; Charlier, J. C.

    2005-10-01

    Inductive coupled rf-plasma at 13.56 MHz was used to modify multiwalled carbon nanotubes (MWCNTs). This technique can be easily used to tailor the chemical composition of carbon nanotubes by attaching a wide variety of functional groups at their surface: oxygen-, nitrogen-, and fluorine-containing groups have been grafted. The influence of various plasma conditions (power, type of gas, treatment time, pressure, position of the CNT sample inside the chamber) on the functionalization of the MWCNT surface was analyzed by x-ray photoelectron spectroscopy. The results show that for too high oxygen plasma power, chemical etching occurs at the surface of the CNT, thus destroying its structure. On the other hand, for optimal values of the plasma parameters, functional groups (hydroxide, carbonyl, carboxyl, amine, fluorine, etc.) were found to bond to the CNT surface, suggesting that both the concentration and type of the functional groups are in close connection with the plasma conditions. These results were compared to interaction energies predicted by ab initio calculations for different functional groups under consideration, showing that functionalization by oxygen plasma produces mainly functional groups with lower interaction energy.

  2. High temperature reactive ion etching of iridium thin films with aluminum mask in CF4/O2/Ar plasma

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Pin; Lisker, Marco; Kalkofen, Bodo; Burte, Edmund P.

    2016-08-01

    Reactive ion etching (RIE) technology for iridium with CF4/O2/Ar gas mixtures and aluminum mask at high temperatures up to 350 °C was developed. The influence of various process parameters such as gas mixing ratio and substrate temperature on the etch rate was studied in order to find optimal process conditions. The surface of the samples after etching was found to be clean under SEM inspection. It was also shown that the etch rate of iridium could be enhanced at higher process temperature and, at the same time, very high etching selectivity between aluminum etching mask and iridium could be achieved.

  3. On the etching characteristics and mechanisms of HfO2 thin films in CF4/O2/Ar and CHF3/O2/Ar plasma for nano-devices.

    PubMed

    Lim, Nomin; Efremov, Alexander; Yeom, Geun Young; Kwon, Kwang-Ho

    2014-12-01

    The study of etching characteristics and mechanisms for HfO2 and Si in CF4/O2/Ar and CHF3/O2/Ar inductively-coupled plasmas was carried out. The etching rates of HfO2 thin films as well as the HfO2/Si etching selectivities were measured as functions of Ar content in a feed gas (0-50% Ar) at fixed fluorocarbon gas content (50%), gas pressure (6 mTorr), input power (700 W), bias power (200 W), and total gas flow rate (40 sccm). Plasma parameters as well as the differences in plasma chemistries for CF4- and CHF3-based plasmas were analyzed using Langmuir probe diagnostics and 0-dimensional plasma modeling. It was found that, in both gas systems, the non-monotonic (with a maximum at about 15-20% Ar) HfO2 etching rate does not correlate with monotonic changes of F atom flux and ion energy flux. It was proposed that, under the given set of experimental conditions, the HfO2 etching process is affected by the factors determining the formation and decomposition kinetics of the fluorocarbon polymer layer. These factor are the fluxes of CF(x) (x = 1, 2) radicals, O atoms and H atoms.

  4. Computational study of the CF4 /CHF3 / H2 /Cl2 /O2 /HBr gas phase plasma chemistry

    NASA Astrophysics Data System (ADS)

    Tinck, Stefan; Bogaerts, Annemie

    2016-05-01

    A modelling study is performed of high-density low-pressure inductively coupled CF4/CHF3/H2/Cl2/O2/HBr plasmas under different gas mixing ratios. A reaction set describing the complete plasma chemistry is presented and discussed. The gas fraction of each component in this mixture is varied to investigate the sensitivity of the plasma properties, like electron density, plasma potential and species densities, towards the gas mixing ratios. This research is of great interest for microelectronics applications because these gases are often combined in two (or more)-component mixtures, and mixing gases or changing the fraction of a gas can sometimes yield unwanted reaction products or unexpected changes in the overall plasma properties due to the increased chemical complexity of the system. Increasing the CF4 fraction produces more F atoms for chemical etching as expected, but also more prominently lowers the density of Cl atoms, resulting in an actual drop in the etch rate under certain conditions. Furthermore, CF4 decreases the free electron density when mixed with Cl2. However, depending on the other gas components, CF4 gas can also sometimes enhance free electron density. This is the case when HBr is added to the mixture. The addition of H2 to the gas mixture will lower the sputtering process, not only due to the lower overall positive ion density at higher H2 fractions, but also because more H+, \\text{H}2+ and \\text{H}3+ are present and they have very low sputter yields. In contrast, a larger Cl2 fraction results in more chemical etching but also in less physical sputtering due to a smaller abundance of positive ions. Increasing the O2 fraction in the plasma will always lower the etch rate due to more oxidation of the wafer surface and due to a lower plasma density. However, it is also observed that the density of F atoms can actually increase with rising O2 gas fraction. This is relevant to note because the exact balance between fluorination and oxidation is

  5. Numerical Modeling of Heat-Mass Transfer in Radial Flow Plasma-Chemical Reactor with Multicomponent Kinetics CF4/02

    DTIC Science & Technology

    2002-08-23

    that the effect of CF3 adsorption on etching rate does not exceed 5%. In CF4/O2 plasma the oxygen reacts with CFx radicals preventing their...realized at the small gas flow rates (Table 1, gas flow rate 100 cm3/min). Here it is possible the effective control of etching rate by changing the...rates (100 cm3/min) where fluorine transfer is determined by a concentration diffusion to the wafer. Here it is possible the effective control of

  6. Improvement in performance and reliability with CF4 plasma pretreatment on the buffer oxide layer for low-temperature polysilicon thin-film transistor

    NASA Astrophysics Data System (ADS)

    Fan, Ching-Lin; Lin, Yi-Yan; Yang, Chun-Chieh

    2012-03-01

    This study applies CF4 plasma pretreatment to a buffer oxide layer to improve the performance of low-temperature polysilicon thin-film transistors (LTPS TFTs). Results show that the fluorine atoms piled up at the interface between the bulk channel and buffer oxide layer and accumulated in the bulk channel. The reduction of the trap states density by fluorine passivation can improve the electrical characteristics of the LTPS TFTs. It is found that the threshold voltage reduced from 4.32 to 3.03 V and the field-effect mobility increased from 29.71 to 45.65 cm2 V-1 S-1. In addition, the on current degradation and threshold voltage shift after stressing were significantly improved about 31% and 70%, respectively. We believe that the proposed CF4 plasma pretreatment on the buffer oxide layer can passivate the trap states and avoid the plasma induced damage on the polysilicon channel surface, resulting in the improvement in performance and reliability for LTPS-TFT mass production application on AMOLED displays with critical reliability requirement.

  7. Effect of gas properties on the dynamics of the electrical slope asymmetry effect in capacitive plasmas: comparison of Ar, H2 and CF4

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Korolov, I.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Diomede, P.; Economou, D. J.; Longo, S.; Johnson, E.; Booth, J.-P.

    2016-02-01

    Tailored voltage excitation waveforms provide an efficient control of the ion energy (through the electrical asymmetry effect) in capacitive plasmas by varying the ‘amplitude’ asymmetry of the waveform. In this work, the effect of a ‘slope’ asymmetry of the waveform is investigated by using sawtooth-like waveforms, through which the sheath dynamic can be manipulated. A remarkably different discharge dynamic is found for Ar, H2, and CF4 gases, which is explained by the different dominant electron heating mechanisms and plasma chemistries. In comparison to Argon we find that the electrical asymmetry can even be reversed by using an electronegative gas such as CF4. Phase resolved optical emission spectroscopy measurements, probing the spatiotemporal distribution of the excitation rate show excellent agreement with the results of particle-in-cell simulations, confirming the high degree of correlation between the excitation rates with the dominant heating mechanisms in the various gases. It is shown that, depending on the gas used, sawtooth-like voltage waveforms may cause a strong asymmetry.

  8. High Performance Enhancement-Mode AlGaN/GaN MOSHEMT using Bimodal-Gate-Oxide and CF4 Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Pang, Liang; Kim, Kyekyoon

    2013-03-01

    To realize GaN E-mode HEMTs, CF4 plasma treatment is commonly used. However, comparable performance as the D-mode counterpart has yet to be achieved, since the F-ions implanted into 2DEG degrade the electron mobility by impurity scattering. In this study, a bimodal-gate-oxide scheme is developed, where ALD-Al2O3is utilized to prevent deep ion implantation, and sputtered-SiO2 is employed to suppress plasma-induced leakage current. Firstly, with the Al2O3 energy barrier, the CF4-plasma-treated MOSHEMT increased Vth from -3 V to 0 V, while Imax was only reduced from 503 mA/mm to 460 mA/mm. SIMS measurements confirmed that F- ions were accumulated in the top 5 nm of Al2O3, and the 2DEG impurity concentration was 10 times smaller than the conventional structure. However, due to the gate leakage current through plasma-generated defects in Al2O3, the device exhibited small gate swing of 2 V. Therefore, before gate metal deposition, a SiO2 film was sputtered at room temperature in a self-aligned manner. The highly condensed sputtered-SiO2 was effective in blocking the leakage current. Thus-fabricated bimodal-MOSHEMT exhibited Vth of 0 V, gate swing of 5 V, and Imaxof 462 mA/mm. The small 8% current degradation when converting from D-mode to E-mode is better than previous results. The MOCVD AlGaN/GaN templates used in this work were provided by Kyungpook National University, Korea for which we are grateful to Prof. Jung-Hee Lee and Mr. Dong-Seok Kim.

  9. Surface modification of hexatriacontane by CF_4 plasmas studied by optical emission and threshold ionization mass spectrometries

    NASA Astrophysics Data System (ADS)

    Poncin-Epaillard, F.; Wang, W.; Ausserré, D.; Scharzenbach, W.; Derouard, J.; Sadeghi, N.

    1998-11-01

    The behavior of tetrafluoromethane microwave plasma (2% argon included) has been studied by emission spectroscopy during the treatment of hexatriacontane, a model for high density polyethylene. The evolution of the densities of F* atoms, and CF, CF^*2, radicals has been followed by using the actinometric technique with 2% argon added to the gas. The surface properties, such as surface energy and surface roughness were correlated to the emission intensity of reactives species in the plasma gas phase. We found that the evolution of the fluorinated species emissions in the plasma gas phase can be a direct indication of the surface modifications by the plasma. A mild exposure to the plasma can result in a great decrease of surface energy corresponding to the fluorination. The surface roughness only changes under drastic plasma conditions. Threshold ionization mass spectroscopy is applied to detect the fluorine atoms and CFx radicals. Time resolved measurements in pulsed plasma, give access to the decay rate of F atoms concentration in the afterglow, and to their sticking coefficient on different surfaces. The influences of the discharge parameters and of the surfaces (metal, silicon or hexatriacontane) in contact with the plasma are investigated. The results show that the plasma generated ions and/or UV radiations highly enhance the reactivity of the F atoms on polymer surface.

  10. Quantitative Analysis of CF4 Produced in the SiO2 Etching Process Using c-C4F8, C3F8, and C2F6 Plasmas by In Situ Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Furuya, Kenji; Hatano, Yoshihiko

    2004-01-01

    The use of CF32+ as a specific product ion to selectively quantify CF4 produced in the SiO2 etching process using plasmas of perfluorocompounds (PFCs), such as c-C4F8, C3F8, and C2F6, has been proposed and investigated in the present experiments by measuring mass spectra inside and outside the plasmas. It is known that the CF32+ ion does not appear in the mass spectra of any stable PFCs, except for CF4. It is confirmed in the present experiments that the quantity of CF32+ originating from the CF3 radical in the mass spectra measured in situ is negligible. Other unstable chemical species in the plasmas are too small in quantity to explain the intensity of CF32+ appearing in the mass spectra measured in situ, even if they could produce stable CF32+ by ionization. It is therefore concluded that CF32+ can be used as a fingerprint of CF4 in mass spectrometry. Application of this new method for the quantitative analysis of CF4 produced in the SiO2 etching process using PFC plasmas results in CF4 production advancing significantly not only in the etching region of SiO2 but also in the downstream region of the plasmas.

  11. Use of statistical design of experiments for surface modification of Kapton films by CF4sbnd O2 microwave plasma treatment

    NASA Astrophysics Data System (ADS)

    Grandoni, Andrea; Mannini, Giacomo; Glisenti, Antonella; Manariti, Antonella; Galli, Giancarlo

    2017-10-01

    A statistical design of experiments (DoE) was used to evaluate the effects of CF4sbnd O2 plasma on Kapton films in which the duration of treatment, volume ratio of plasma gases, and microwave power were selected as effective experimental factors for systematic investigation of surface modification. Static water contact angle (θW), polar component of surface free energy (γSp) and surface O/C atomic ratio were analyzed as response variables. A significant enhancement in wettability and polarity of the treated films compared to untreated Kapton films was observed; depending on the experimental conditions, θW very significantly decreased, showing full wettability, and γSp rose dramatically, up to ten times. Within the DoE the conditions of plasma treatment were identified that resulted in selected optimal values of θW, γSp and O/C responses. Surface chemical changes were detected by XPS and ATR-IR investigations that evidenced both the introduction of fluorinated groups and the opening of the imide ring in the plasma-treated films.

  12. Irradiation of poly(tetrafluoroethylene) surfaces by CF4 plasma to achieve robust superhydrophobic and enhanced oleophilic properties for biological applications.

    PubMed

    Salapare, Hernando S; Suarez, Beverly Anne T; Cosiñero, Hannah Shamina O; Bacaoco, Miguel Y; Ramos, Henry J

    2015-01-01

    Poly(tetrafluoroethylene) (PTFE) was irradiated by CF4 plasma produced in the gas discharge ion source facility to produce stable and robust superhydrophobic surfaces and to enhance the materials' oleophilic property for biological applications. The characterizations employed on the samples are contact angle measurements, analysis of the surface morphology (scanning electron microscopy), surface roughness measurements (atomic force microscopy) and analysis of the surface chemistry (Fourier transform infrared spectroscopy). Superhydrophobic behavior with water contact angles as high as 156° was observed. The wettability of all the treated samples was found to be stable in time as evidenced by the statistically insignificant differences in the hysteresis contact angles. The level of enhanced hydrophobicity depended on the plasma energies (i.e. irradiation times, discharge current, and discharge voltage); higher plasma energies produced surfaces with high hydrophobicity. The plasma treatment also enhanced the oleophilic property of the materials' surface as evidenced by the decrease in the PDMS-oil contact angle from 33° to as low as 10°. The superhydrophobicity of the modified PTFE and the enhancement of its oleophilic property were due to (1) the changes in the roughness of the surface, (2) the formation of nanoparticles or nanostructures on the surface, and (3) the changes in the surface chemistry.

  13. Reactive ion etching effects on carbon-doped Ge2Sb2Te5 phase change material in CF4/Ar plasma

    NASA Astrophysics Data System (ADS)

    Shen, Lanlan; Song, Sannian; Song, Zhitang; Li, Le; Guo, Tianqi; Liu, Bo; Wu, Liangcai; Cheng, Yan; Feng, Songlin

    2016-10-01

    Recently, carbon-doped Ge2Sb2Te5 (CGST) has been proved to be a high promising material for future phase change memory technology. In this article, reactive ion etching (RIE) of phase change material CGST films is studied using CF4/Ar gas mixture. The effects on gas-mixing ratio, RF power, gas pressure on the etch rate, etch profile and roughness of the CGST film are investigated. Conventional phase change material Ge2Sb2Te5 (GST) films are simultaneously studied for comparison. Compared with GST film, 10 % more CF4 is needed for high etch rate and 10% less CF4 for good anisotropy of CGST due to more fluorocarbon polymer deposition during CF4 etching. The trends of etch rates and roughness of CGST with varying RF power and chamber pressure are similar with those of GST. Furthermore, the etch rate of CGST are more easily to be saturated when higher RF power is applied.

  14. [The spectra of a laser-produced plasma source with CO2, O2 and CF4 liquid aerosol spray target].

    PubMed

    Ni, Qi-Liang; Chen, Bo

    2008-11-01

    A laser-produced plasma (LPP) source with liquid aerosol spray target and nanosecond laser was developed, based on both soft X-ray radiation metrology and extreme ultraviolet projection lithography (EUVL). The LPP source is composed of a stainless steel solenoid valve whose temperature can be continuously controlled, a Nd : YAG laser with pulse width, working wavelength and pulse energy being 7 ns, 1.064 microm and 1J respectively, and a pulse generator which can synchronously control the valve and the laser. A standard General Valve Corporation series 99 stainless steel solenoid valve with copper gasket seals and a Kel-F poppet are used in order to minimize leakage and poppet deformation during high-pressure cryogenic operation. A close fitting copper cooling jacket surrounds the valve body. The jacket clamps a copper coolant carrying tube 3 mm in diameter, which is fed by an automatically pressurized liquid nitrogen-filled dewar. The valve temperature can be controlled between 77 and 473 K. For sufficiently high backing pressure and low temperature, the valve reservoir gas can undergo a gas-to-liquid phase transition. Upon valve pulsing, the liquid is ejected into a vacuum and breaks up into droplets, which is called liquid aerosol spray target. For the above-mentioned LPP source, firstly, by the use of Cowan program on the basis of non-relativistic quantum mechanics, the authors computed the radiative transition wavelengths and probabilities in soft X-ray region for O4+, O5+, O6+, O7+, F5+, F6+ and F7+ ions which were correspondingly produced from the interaction of the 10(11)-10(12) W x cm(-2) power laser with liquid O2, CO2 and CF4 aerosol spray targets. Secondly, the authors measured the spectra of liquid O2, CO2 and CF4 aerosol spray target LPP sources in the 6-20 nm band for the 8 x 10(11) W x cm(-2) laser irradiance. The measured results were compared with the Cowan calculated results ones, and the radiative transition wavelength and probability for the

  15. Student Award Finalist: Comparison of the effect of sawtooth-like voltage waveforms on discharge dynamics of Ar, H2, and CF4 plasmas

    NASA Astrophysics Data System (ADS)

    Bruneau, Bastien; Johnson, E.; Gans, T.; O'Connell, D.; Greb, A.; Korolov, I.; Derzsi, A.; Donko, Z.; Schungel, E.; Brandt, S.; Schulze, J.; Diomede, P.; Economou, D. J.; Longo, S.; Lafleur, T.; Booth, J.-P.

    2015-09-01

    The use of Tailored Voltage Waveforms to excite a plasma has been previously shown to efficiently control the ion energy (through the Electrical Asymmetry Effect) by varying the ``amplitude'' asymmetry of the waveform. In this work, the effect of a ``slope'' asymmetry of the waveform is investigated by using sawtooth-like waveforms. When a discharge is excited with such a waveform, one sheath expands rapidly and contracts slowly, while the reverse occurs at the other sheath. While using such waveforms, different discharge gases are compared, namely Ar (as an electropositive gas), H2 (as a light gas), and CF4 (as an electronegative gas). For each gas, phase resolved optical emission spectroscopy measurements are compared with PIC simulations, showing excellent agreement. The dynamics of the excitation rates are very different for the different gases and are shown to be correlated with the dominant heating mechanisms. It is shown that the asymmetry obtained with sawtooth-like voltage waveforms can be very large, and can even be reversed, depending on the gas used.

  16. Dry etching of beta-SiC in CF4 and CF4 + O2 mixtures

    NASA Technical Reports Server (NTRS)

    Palmour, J. W.; Davis, R. F.; Wallett, T. M.; Bhasin, K. B.

    1986-01-01

    Dry etching of cubic (100) beta-SiC single-crystal thin films produced via chemical-vapor deposition (CVD) has been performed in CF4 and CF4 + O2 mixtures, in both the reactive-ion-etching (RIE) and plasma-etching modes. The latter process yielded measurable etch rates, but produced a dark surface layer which appears, from the results of secondary-ion mass spectrometry, to be residual SiC. The RIE samples had no residual layer, but Auger electron spectroscopy did reveal a C-rich surface. The optimal RIE conditions were obtained with 10 sccm of pure CF4 at 40 mtorr and a power density of 0.548 W/sq cm, giving an etch rate of 23.3 nm/min. Neither the increase of temperature between 293 and 573 K, nor the incremental addition of O2 to CF4 to 50 percent, produced any strong effect on the etch rates of SiC during RIE. Pictorial evidence of fine line structures produced by RIE of beta-SiC films are also presented.

  17. Reactive ion etching of Si(x)Sb2Te in CF4/Ar plasma for nonvolatile phase-change memory device.

    PubMed

    Gu, Yifeng; Song, Sannian; Song, Zhitang; Cheng, Yan; Liu, Xuyan; Du, Xiaofeng; Liu, Bo; Feng, Songlin

    2013-02-01

    Si(x)Sb2Te material system is novel for phase-change random access memory applications. Its properties are more outstanding than the widely used material Ge2Sb2Te5. Etching process is one of the critical steps in the device fabrication. The etching characteristics of phase-change material Si(x)Sb2Te were studied with CF4/Ar gas mixture by a reactive ion etching system. The changes of etching rate, etching profile and surface root-mean-square roughness resulted from variation of the gas-mixing ratio were investigated under constant pressure (50 mTorr) and applying power (200 W). Si0.34Sb2Te is with the highest phase-change speed and the lowest power consumption in the PCRAM memory among these compositions, which means it is the most promising candidate for the PCRAM applications. So the most optimized CF4/Ar gas ratio for Si0.34Sb2Te was studied, the value is 25/25. The etching rate is 155 nm/min, and the selectivity of Si0.34Sb2Te to SiO2 is as high as 3.4 times. Furthermore, the smooth surface was achieved with this optimized gas ratio.

  18. Measurements of negative ion densities in 13.56-MHz rf plasmas of CF4, C2F6, CHF3, and C3F8 using microwave resonance and the photodetachment effect

    NASA Astrophysics Data System (ADS)

    Haverlag, M.; Kono, A.; Passchier, D.; Kroesen, G. M. W.; Goedheer, W. J.; de Hoog, F. J.

    1991-10-01

    The high-power density of a frequency quadrupled pulsed Nd-YAG laser has been used to photodetach electrons from negative ions in rf plasmas generated within a microwave cavity. Negative ion densities have been determined by measuring the frequency shift of the resonance transmission, the shift being caused by the photoelectrons created by irradiating the plasma with the laser pulse. By measurement of the shape of the resonance curve as a function of time and of microwave frequency, and consecutive fitting of a parabola to the top of the resonance curve, the negative ion density has been determined as a function of gas pressure, rf power, and position in the plasma. Measurements were performed in plasmas of CF4, C2F6, CHF3, and C3F8. The results indicate that the negative ion densities are about one order of magnitude larger than the electron density, which is in good agreement with a fluid model calculation. The pressure and power dependence of the electron density and of the negative ion density gives insight in the relation between the electron temperature and the macroscopic plasma parameters. Measurements as a function of the laser wavelength, using a pulsed dye laser, show that in CF4 the negative ions mainly consist of F-, whereas in C2F6 significant densities of other negative ions may occur.

  19. Theoretical computation of thermophysical properties of high-temperature F2, CF4, C2F2, C2F4, C2F6, C3F6 and C3F8 plasmas

    NASA Astrophysics Data System (ADS)

    Wang, WeiZong; Wu, Yi; Rong, MingZhe; Éhn, László; Černušák, Ivan

    2012-07-01

    The calculated values of thermodynamic and transport properties of pure F2 and fluorocarbon compounds CF4, C2F2, C2F4, C2F6, C3F6 and C3F8 at high temperatures are presented in this paper. The thermodynamic properties are determined by the method of Gibbs free energy minimization, using standard thermodynamic tables. The transport properties, including electron diffusion coefficients, viscosity, thermal conductivity and electrical conductivity, are evaluated using the Chapman-Enskog method expanded up to the third-order approximation (second order for viscosity). The most accurate cross-section data that could be located are used to evaluate collision integrals. The calculations based on the assumption of local thermodynamic equilibrium are performed for atmospheric-pressure plasmas in the temperature range from 300 to 30 000 K for different pressures between 0.1 and 10 atm. The results of F2, CF4, C2F2, C2F4 and C2F6 are compared with those of previously published studies. Larger discrepancies occur for transport coefficients; these are explained in terms of the different values of the collision integrals that were used. The results presented here are expected to be more accurate because of the improved collision integrals employed.

  20. Electronic structures of Ga2O3(Gd2O3) gate dielectric on n-Ge(001) as grown and after CF4 plasma treatment: A synchrotron-radiation photoemission study

    NASA Astrophysics Data System (ADS)

    Pi, T.-W.; Lee, W. C.; Huang, M. L.; Chu, L. K.; Lin, T. D.; Chiang, T. H.; Wang, Y. C.; Wu, Y. D.; Hong, M.; Kwo, J.

    2011-03-01

    The interfacial electronic structure of Ga2O3(Gd2O3) (GGO) on n-Ge(001) is determined using high-resolution synchrotron radiation photoemission. The excitation photon energy was specifically chosen to observe the interaction at the GGO/Ge interface (hv = 463 eV) as well as the possible diffusion of Ge up to the GGO surface (hν = 120 eV). The Ge 3d core-level spectra were fit to extract the contributing components. Photoemission measurements were done for four samples, as deposited, N2 annealed, CF4 plasma treated, and the combined CF4 plasma treated and N2 annealed. No surface passivation was employed prior to the dielectric deposition. SRPES data clearly showed that the elemental Ge in the as-deposited sample was effectively kept in the wafer. Prevention of Ge diffusion was attributed to formation of a thin germanatelike oxide layer. Other than contributions from bulk Ge, an analytical fit to the Ge 3d cores gives two components that are associated with bonding to Gd2O3 (GdGe*) and to Ga2O3 (GaGe*), which had chemical shifts of 3.46 and 1.80 eV, respectively. We hereby label them as MGe*, where M stands for either Gd2O3 or Ga2O3. Area occupations of the GdGe* and GaGe* oxides are ˜87% and ˜10%, respectively. A CF4 plasma treatment disturbs the film itself as well as the interfacial oxide so that the GGO surface begins to show both elemental Ge and Ga. Nevertheless, the follow-up N2 annealing produces the GdGe*+GaGe* layer with characteristics similar to those at the GGO/Ge interface. Both GdGe* and GaGe* states in the CN-treated sample show simultaneously a smaller chemical shift by 0.31 ± 0.02 eV than those in the as-deposited sample. The treatments also induce upward band bending on both the high κ and the Ge sides, which causes the valence band offset at the GGO/Ge interface to be 2.95 eV.

  1. Comparison of Erosion Behavior and Particle Contamination in Mass-Production CF4/O2 Plasma Chambers Using Y2O3 and YF3 Protective Coatings

    PubMed Central

    Lin, Tzu-Ken; Wang, Wei-Kai; Huang, Shih-Yung; Tasi, Chi-Tsung

    2017-01-01

    Yttrium fluoride (YF3) and yttrium oxide (Y2O3) protective coatings prepared using an atmospheric plasma spraying technique were used to investigate the relationship between surface erosion behaviors and their nanoparticle generation under high-density plasma (1012–1013 cm−3) etching. As examined by transmission electron microscopy, the Y2O3 and YF3 coatings become oxyfluorinated after exposure to the plasma, wherein the yttrium oxyfluoride film formation was observed on the surface with a thickness of 5.2 and 6.8 nm, respectively. The difference in the oxyfluorination of Y2O3 and YF3 coatings could be attributed to Y–F and Y–O bonding energies. X-ray photoelectron spectroscopy analyses revealed that a strongly fluorinated bonding (Y–F bond) was obtained on the etched surface of the YF3 coating. Scanning electron microscopy and energy dispersive X-ray diffraction analysis revealed that the nanoparticles on the 12-inch wafer are composed of etchant gases and Y2O3. These results indicate that the YF3 coating is a more erosion-resistant material, resulting in fewer contamination particles compared with the Y2O3 coating. PMID:28708079

  2. Influence of power on the surface loss reaction of F radicals in a low pressure CF4:O2 ICP discharge

    NASA Astrophysics Data System (ADS)

    Setareh, Mahsa; Farnia, Morteza; Maghari, Ali; University of Tehran Team

    2014-10-01

    A zero dimensional modeling code Global_kin, developed by Kushner is applied to model the CF4/O2 radio frequency inductively coupled plasma at applied powers of 80-300 W, pressure of 25 mTorr and temperature of 400 K. The calculated results indicated that the Fluorine (F) is the dominant radical produced in CF4:O2 discharge which is lost mostly at the walls rather than in formation of F2 molecules. We calculated the time integrated rate of F loss at the wall together with the relative contribution of wall reactions on the total loss of F corresponding to the sticking probabilities. The model predicts that although the absolute time integrated loss rates at the walls increase with power, but the relative contribution of the wall loss process decreases slightly upon higher powers. Furthermore, at lower O2 contents (or high CF4 contents), the relative contribution of the wall loss process is much lower because F radicals can also get lost in reactions with other plasma species such as CF3 to form again CF4. At equal contents of O2 and CF4, 35-45% of the F radicals are lost at the walls, depending on the power. The numerical modeling results for CF4 decomposition into new products are validated based on experimental data from literature.

  3. A high level computational study of the CH4/CF4 dimer: how does it compare with the CH4/CH4 and CF4/CF4 dimers?

    NASA Astrophysics Data System (ADS)

    Biller, Matthew J.; Mecozzi, Sandro

    2012-04-01

    The interaction within the methane-methane (CH4/CH4), perfluoromethane-perfluoromethane (CF4/CF4) methane-perfluoromethane dimers (CH4/CF4) was calculated using the Hartree-Fock (HF) method, multiple orders of Møller-Plesset perturbation theory [MP2, MP3, MP4(DQ), MP4(SDQ), MP4(SDTQ)], and coupled cluster theory [CCSD, CCSD(T)], as well as the PW91, B97D, and M06-2X density functional theory (DFT) functionals. The basis sets of Dunning and coworkers (aug-cc-pVxZ, x = D, T, Q), Krishnan and coworkers [6-311++G(d,p), 6-311++G(2d,2p)], and Tsuzuki and coworkers [aug(df, pd)-6-311G(d,p)] were used. Basis set superposition error (BSSE) was corrected via the counterpoise method in all cases. Interaction energies obtained with the MP2 method do not fit with the experimental finding that the methane-perfluoromethane system phase separates at 94.5 K. It was not until the CCSD(T) method was considered that the interaction energy of the methane-perfluoromethane dimer (-0.69 kcal mol-1) was found to be intermediate between the methane (-0.51 kcal mol-1) and perfluoromethane (-0.78 kcal mol-1) dimers. This suggests that a perfluoromethane molecule interacts preferentially with another perfluoromethane (by about 0.09 kcal mol-1) than with a methane molecule. At temperatures much lower than the CH4/CF4 critical solution temperature of 94.5 K, this energy difference becomes significant and leads perfluoromethane molecules to associate with themselves, forming a phase separation. The DFT functionals yielded erratic results for the three dimers. Further development of DFT is needed in order to model dispersion interactions in hydrocarbon/perfluorocarbon systems.

  4. A CF4 based positron trap

    NASA Astrophysics Data System (ADS)

    Marjanović, Srdjan; Banković, Ana; Cassidy, David; Cooper, Ben; Deller, Adam; Dujko, Saša; Petrović, Zoran Lj

    2016-11-01

    All buffer-gas positron traps in use today rely on N2 as the primary trapping gas due to its conveniently placed {{{a}}}1{{\\Pi }} electronic excitation cross-section. The energy loss per excitation in this process is 8.5 eV, which is sufficient to capture positrons from low-energy moderated beams into a Penning-trap configuration of electric and magnetic fields. However, the energy range over which this cross-section is accessible overlaps with that for positronium (Ps) formation, resulting in inevitable losses and setting an intrinsic upper limit on the overall trapping efficiency of ∼25%. In this paper we present a numerical simulation of a device that uses CF4 as the primary trapping gas, exploiting vibrational excitation as the main inelastic capture process. The threshold for such excitations is far below that for Ps formation and hence, in principle, a CF4 trap can be highly efficient; our simulations indicate that it may be possible to achieve trapping efficiencies as high as 90%. We also report the results of an attempt to re-purpose an existing two-stage N2-based buffer-gas positron trap. Operating the device using CF4 proved unsuccessful, which we attribute to back scattering and expansion of the positron beam following interactions with the CF4 gas, and an unfavourably broad longitudinal beam energy spread arising from the magnetic field differential between the source and trap regions. The observed performance was broadly consistent with subsequent simulations that included parameters specific to the test system, and we outline the modifications that would be required to realise efficient positron trapping with CF4. However, additional losses appear to be present which require further investigation through both simulation and experiment.

  5. Reduced mobility of He+ in CF4

    NASA Astrophysics Data System (ADS)

    Nikitović, Ž. D.; Raspopović, Z. M.; Stojanović, V. D.

    2017-04-01

    This paper is devoted to a presentation of a cross section set for the scattering of He+ ions in CF4, which is assessed by using available experimental data for exothermic charge transfer cross sections that produce {{{{CF}}}3}+ and {{{{CF}}}2}+ ions and endothermic charge transfer cross sections that produce CF+, C+ and F+ ions. Due to the significant particle losses, experimental transport coefficients have not been measured. Transport properties of He+ ions in CF4 needed for modeling discharges containing mentioned ions are calculated by the Monte Carlo method at a temperature of T = 300 K. Significant differences between flux and bulk transport coefficients are noticed, which is important for fluid models that exploit flux transport coefficients as input data.

  6. Gladstone-Dale constant for CF4

    NASA Astrophysics Data System (ADS)

    Burner, A. W., Jr.; Goad, W. K.

    1980-05-01

    The Gladstone-Dale constant, which relates the refractive index to density, was measured for CF4 by counting fringes of a two-beam interferometer, one beam of which passes through a cell containing the test gas. The experimental approach and sources of systematic and imprecision errors are discussed. The constant for CF4 was measured at several wavelengths in the visible region of the spectrum. A value of 0.122 cu cm/g with an uncertainty of plus or minus 0.001 cu cm/g was determined for use in the visible region. A procedure for noting the departure of the gas density from the ideal-gas law is discussed.

  7. Impact of Gas Heating in Inductively Coupled Plasmas

    NASA Technical Reports Server (NTRS)

    Hash, D. B.; Bose, D.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Sharma, S. P.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Recently it has been recognized that the neutral gas in inductively coupled plasma reactors heats up significantly during processing. The resulting gas density variations across the reactor affect reaction rates, radical densities, plasma characteristics, and uniformity within the reactor. A self-consistent model that couples the plasma generation and transport to the gas flow and heating has been developed and used to study CF4 discharges. A Langmuir probe has been used to measure radial profiles of electron density and temperature. The model predictions agree well with the experimental results. As a result of these comparisons along with the poorer performance of the model without the gas-plasma coupling, the importance of gas heating in plasma processing has been verified.

  8. Fourier Transform Infrared Spectroscopy of CF4 on the GEC Reference Cell

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Sharma, S. P.; Meyyappan, M.; Cruden, Brett A.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Fourier Transform Infrared Spectroscopy (FTIR) has been used to characterize inductively coupled CF4 plasmas in a GEC Reference Cell in-situ In examining these FTIR spectra, several assumptions and approximations of FTIR analysis are addressed. This includes the density dependence of cross-sections, non-linear effects in the addition of overlapping bands and the effect of spatial variations in density and temperature, This analysis demonstrates that temperatures extracted from MR spectra may provide a poor estimate of the true neutral plasma temperature. The FTIR spectra are dominated by unreacted CF, accounting for 40-60% of the gas products. The amount of CF4 consumption is found to have a marked dependence on power, and is nearly independent of pressure in the range of 10-50 mtorr. Small amounts of C2F6 are observed at low power. Also observed are etching products from the quartz window SiF4 COF2 and CO which occur in approximately equal ratios and together account for less than 10% of the gas. The concentrations of these species are nearly independent of pressure. CFx radicals are below the detection limit of this apparatus (approx. 1012/cc).

  9. Fourier Transform Infrared Spectroscopy of CF4 on the GEC Reference Cell

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Sharma, S. P.; Meyyappan, M.; Cruden, Brett A.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Fourier Transform Infrared Spectroscopy (FTIR) has been used to characterize inductively coupled CF4 plasmas in a GEC Reference Cell in-situ In examining these FTIR spectra, several assumptions and approximations of FTIR analysis are addressed. This includes the density dependence of cross-sections, non-linear effects in the addition of overlapping bands and the effect of spatial variations in density and temperature, This analysis demonstrates that temperatures extracted from MR spectra may provide a poor estimate of the true neutral plasma temperature. The FTIR spectra are dominated by unreacted CF, accounting for 40-60% of the gas products. The amount of CF4 consumption is found to have a marked dependence on power, and is nearly independent of pressure in the range of 10-50 mtorr. Small amounts of C2F6 are observed at low power. Also observed are etching products from the quartz window SiF4 COF2 and CO which occur in approximately equal ratios and together account for less than 10% of the gas. The concentrations of these species are nearly independent of pressure. CFx radicals are below the detection limit of this apparatus (approx. 1012/cc).

  10. Photoionisation study of Xe.CF4 and Kr.CF4 van-der-Waals molecules.

    PubMed

    Alekseev, V A; Garcia, G A; Kevorkyants, R; Nahon, L

    2016-05-14

    We report on photoionization studies of Xe.CF4 and Kr.CF4 van-der-Waals complexes produced in a supersonic expansion and detected using synchrotron radiation and photoelectron-photoion coincidence techniques. The ionization potential of CF4 is larger than those of the Xe and Kr atoms and the ground state of the Rg.CF4 (+) ion correlates with Rg(+) ((2)P3/2) + CF4. The onset of the Rg.CF4 (+) signals was found to be only ∼0.2 eV below the Rg ionization potential. In agreement with experiment, complementary ab initio calculations show that vertical transitions originating from the potential minimum of the ground state of Rg.CF4 terminate at a part of the potential energy surfaces of Rg.CF4 (+), which are approximately 0.05 eV below the Rg(+) ((2)P3/2) + CF4 dissociation limit. In contrast to the neutral complexes, which are most stable in the face geometry, for the Rg.CF4 (+) ions, the calculations show that the minimum of the potential energy surface is in the vertex geometry. Experiments which have been performed only with Xe.CF4 revealed no Xe.CF4 (+) signal above the first ionization threshold of Xe, suggesting that the Rg.CF4 (+) ions are not stable above the first dissociation limit.

  11. Cooking strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Clérouin, Jean

    2015-09-01

    We present the orbital-free method for dense plasmas which allows for efficient variable ionisation molecular dynamics. This approach is a literal application of density functional theory where the use of orbitals is bypassed by a semi-classical estimation of the electron kinetic energy through the Thomas-Fermi theory. Thanks to a coherent definition of ionisation, we evidence a particular regime in which the static structure no longer depends on the temperature: the Γ-plateau. With the help of the well-known Thomas-Fermi scaling laws, we derive the conditions required to obtain a plasma at a given value of the coupling parameter and deduce useful fits. Static and dynamical properties are predicted as well as a a simple equation of state valid on the Γ-plateau. We show that the one component plasma model can be helpful to describe the correlations in real systems.

  12. Inductively coupled helium plasma torch

    DOEpatents

    Montaser, Akbar; Chan, Shi-Kit; Van Hoven, Raymond L.

    1989-01-01

    An inductively coupled plasma torch including a base member, a plasma tube and a threaded insert member within the plasma tube for directing the plasma gas in a tangential flow pattern. The design of the torch eliminates the need for a separate coolant gas tube. The torch can be readily assembled and disassembled with a high degree of alignment accuracy.

  13. DC breakdown in low-pressure CF4

    NASA Astrophysics Data System (ADS)

    Lisovskiy, V. A.; Derevianko, V. A.; Yegorenkov, V. D.

    2015-12-01

    This paper reports the results of studying dc breakdown in low-pressure CF4 gas. We measured the breakdown curves over a broad range of values of CF4 pressure and interelectrode distance L. Two breakdown modes were observed at different CF4 pressures. When the values of the product of gas pressure and gap width are moderate, pL  <  2 Torr cm, a balance is achieved between molecular ionization through electron impact and electron escape to the anode and tube walls due to the drift in the electric field and diffusion, respectively, whereas the attachment of free electrons to CF4 molecules does not play any role. At large values, pL  >  2 Torr cm, the rate of growth of breakdown voltage with pressure essentially increases because a considerable number of electrons may be attached to gas molecules.

  14. A multi-scale approach to characterize pure CH4, CF4, and CH4/CF4 mixtures

    NASA Astrophysics Data System (ADS)

    Chattoraj, Joyjit; Risthaus, Tobias; Rubner, Oliver; Heuer, Andreas; Grimme, Stefan

    2015-04-01

    In this study, we develop three intermolecular potentials for methane (CH4), tetrafluoromethane (CF4), and CH4/CF4 dimers using a novel ab initio method. The ultimate goal is to understand microscopically the phase-separation in CH4/CF4 systems, which takes place in the liquid states near their freezing points. Monte-Carlo (MC) simulations of the pure CH4 system are performed using the ab initio energies to verify the potential. The simulations reproduce quite well the experimentally known liquid densities, the internal energies, the second virial coefficients, and the radial distribution function. The essentially six-dimensional (6D) ab initio potential is then reduced to a one-dimensional (1D) effective potential using the inverse Monte-Carlo technique. This potential, too, successfully reproduces the experimental results. Interestingly, the MC study cannot be extended to the pure CF4 system and the CH4/CF4 mixed system because the two respective ab initio potentials present very rough potential landscapes. This renders the interpolation of energies for the MC simulations and thus the multi-scale approach unreliable. It suggests, however, a possible driving force for the experimentally observed phase separation of the CH4/CF4 system at low temperatures. Furthermore, we carefully study the determination of 1D effective potentials via inverse MC techniques. We argue that to a good approximation the temperature dependence of the 1D potentials can be estimated via reweighting techniques for a fixed temperature.

  15. A multi-scale approach to characterize pure CH4, CF4, and CH4/CF4 mixtures.

    PubMed

    Chattoraj, Joyjit; Risthaus, Tobias; Rubner, Oliver; Heuer, Andreas; Grimme, Stefan

    2015-04-28

    In this study, we develop three intermolecular potentials for methane (CH4), tetrafluoromethane (CF4), and CH4/CF4 dimers using a novel ab initio method. The ultimate goal is to understand microscopically the phase-separation in CH4/CF4 systems, which takes place in the liquid states near their freezing points. Monte-Carlo (MC) simulations of the pure CH4 system are performed using the ab initio energies to verify the potential. The simulations reproduce quite well the experimentally known liquid densities, the internal energies, the second virial coefficients, and the radial distribution function. The essentially six-dimensional (6D) ab initio potential is then reduced to a one-dimensional (1D) effective potential using the inverse Monte-Carlo technique. This potential, too, successfully reproduces the experimental results. Interestingly, the MC study cannot be extended to the pure CF4 system and the CH4/CF4 mixed system because the two respective ab initio potentials present very rough potential landscapes. This renders the interpolation of energies for the MC simulations and thus the multi-scale approach unreliable. It suggests, however, a possible driving force for the experimentally observed phase separation of the CH4/CF4 system at low temperatures. Furthermore, we carefully study the determination of 1D effective potentials via inverse MC techniques. We argue that to a good approximation the temperature dependence of the 1D potentials can be estimated via reweighting techniques for a fixed temperature.

  16. Detection of Chamber Conditioning by CF4 in the GEC Cell

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, S. P.; Meyyappan, M.; Arnold, James (Technical Monitor)

    2001-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalks can cause to drift and will necessitate time for conditioning and cleaning of the reactor. Various measurements in CF4 and Ar plasmas are made in an attempt to identify a metric able to indicate the chamber condition. Mass spectrometry and a Langmuir probe shows that the buildup of fluorocarbon films on the reactor surface causes a decrease in plasma floating potential, plasma potential, and ion energy in argon plasmas. This change in floating potential is also observed in CF4 plasma operation, and occurs primarily during the first hour and a half of plasma operation. A slight rise in electron density is also observed in the argon plasmas. Because the change is seen in an argon plasma, it is indicative of altered physical, not chemical, plasma-surface interactions. Specifically, the insulating films deposited on metal surfaces alter the electromagnetic fields seen by the plasma, affecting various parameters including the floating potential and electron density. An impedance probe placed on the inductive coil shows a slight reduction in plasma impedance due to this rising electron density. The optical emission of several species, including CF, C2, atomic Si and atomic C, is also monitored for changes in density resulting from the buildup of film on the chamber wall. Changes in the optical emission spectrum are comparable to the noise levels in their measurement.

  17. Closed inductively coupled plasma cell

    DOEpatents

    Manning, T.J.; Palmer, B.A.; Hof, D.E.

    1990-11-06

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies is disclosed. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy. 1 fig.

  18. Closed inductively coupled plasma cell

    DOEpatents

    Manning, Thomas J.; Palmer, Byron A.; Hof, Douglas E.

    1990-01-01

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy.

  19. Perspectives on Geospace Plasma Coupling

    SciTech Connect

    Baker, Daniel N.

    2011-01-04

    There are a large variety of fascinating and instructive aspects to examining the coupling of mass and energy from the solar wind into the Earth's magnetosphere. Past research has suggested that magnetic reconnection (in a fluid sense) on the day-side magnetopause plays the key role in controlling the energy coupling. However, both linear and nonlinear coupling processes involving kinetic effects have been suggested through various types of innovative data analysis. Analysis and modeling results have also indicated a prominent role for multi-scale processes of plasma coupling. Examples include evidence of control by solar wind turbulence in the coupling sequence and localized (finite gyroradius) effects in dayside plasma transport. In this paper we describe several solar wind-magnetosphere coupling scenarios. We particularly emphasize the study of solar wind driving of magnetospheric substorm, and related geomagnetic disturbances.

  20. Perspectives on Geospace Plasma Coupling

    NASA Astrophysics Data System (ADS)

    Baker, Daniel N.

    2011-01-01

    There are a large variety of fascinating and instructive aspects to examining the coupling of mass and energy from the solar wind into the Earth's magnetosphere. Past research has suggested that magnetic reconnection (in a fluid sense) on the day-side magnetopause plays the key role in controlling the energy coupling. However, both linear and nonlinear coupling processes involving kinetic effects have been suggested through various types of innovative data analysis. Analysis and modeling results have also indicated a prominent role for multi-scale processes of plasma coupling. Examples include evidence of control by solar wind turbulence in the coupling sequence and localized (finite gyroradius) effects in dayside plasma transport. In this paper we describe several solar wind-magnetosphere coupling scenarios. We particularly emphasize the study of solar wind driving of magnetospheric substorm, and related geomagnetic disturbances.

  1. Etching of Copper Coated Mylar Tubes With CF-4 Gas

    DOE PAGES

    Ecklund, Karl M.; Hartman, Keith W.; Hebert, Michael J.; ...

    1996-04-01

    Using 5 mm diameter copper coated mylar straw tubes at a potential of 2.30 KV relative to a concentric 20 (mu)m diameter gold-plated tungsten anode, it has been observed that with very low flow rates of CF4-based gases the conductive copper cathode material may be removed entirely from the mylar surface.

  2. Langmuir Probe Measurements in an Inductively Coupled GEC Reference Cell Plasma

    NASA Technical Reports Server (NTRS)

    Ji, J. S.; Kim, J. S.; Cappelli, M. A.; Sharma, S. P.; Arnold, J. O. (Technical Monitor)

    1998-01-01

    Measurements of electron number density, electron temperature, and electron energy distribution function (EEDF) using a compensated Langmuir probe have been performed on an inductively (transformer ) coupled Gaseous Electronics Conference (GEC) reference cell plasma. The plasma source is operated with CH4, CF4, or their mixtures with argon. The effect of independently driving the electrode supporting the wafer on the probe data is studied. In particular, we find that the plasma structure depends on the phase in addition to the magnitude of the power coupled to the electrode relative to that of the transformer coil. The Langmuir probe is translated in a plane parallel to the electrode to investigate the spatial structure of the plasma. The probe data is also compared with fluid model predictions.

  3. Gladstone-Dale constant for CF4. [experimental design

    NASA Technical Reports Server (NTRS)

    Burner, A. W., Jr.; Goad, W. K.

    1980-01-01

    The Gladstone-Dale constant, which relates the refractive index to density, was measured for CF4 by counting fringes of a two-beam interferometer, one beam of which passes through a cell containing the test gas. The experimental approach and sources of systematic and imprecision errors are discussed. The constant for CF4 was measured at several wavelengths in the visible region of the spectrum. A value of 0.122 cu cm/g with an uncertainty of plus or minus 0.001 cu cm/g was determined for use in the visible region. A procedure for noting the departure of the gas density from the ideal-gas law is discussed.

  4. Charged particle dynamics and process control in capacitive RF discharges driven by tailored voltage waveforms in mixtures of Argon and CF4

    NASA Astrophysics Data System (ADS)

    Brandt, Steven; Donko, Zoltan; Schulze, Julian

    2016-09-01

    The electron power absorption dynamics and the Electrical Asymmetry Effect (EAE) are computationally investigated for Argon-CF4 gas mixtures in geometrically symmetric capacitively coupled plasmas. Simulations are performed for both single- and triple-frequency tailored voltage waveforms at 20 and 60 Pa, using a fundamental frequency of 13.56 MHz and its consecutive harmonics. The results at 60 Pa show electron power absorption mode transitions between the Drift-Ambipolar (DA) mode and the α-mode induced by varying the admixture of Ar to CF4, which leads to a change of the plasma chemistry. In the triple-frequency cases small argon admixtures (of the order of 10%) strongly affect the electron power absorption dynamics and the symmetry of the discharge. The change of the electrical generation of a DC self-bias via the EAE, the ion flux-energy distribution functions of different ion species at the electrodes, and the excitation of resonance effects are studied as a function of the mixing ratio of these two gases. The results are expected to be highly relevant for plasma processing, where such gas mixtures are often used.

  5. Mobile inductively coupled plasma system

    DOEpatents

    D`Silva, A.P.; Jaselskis, E.J.

    1999-03-30

    A system is described for sampling and analyzing a material located at a hazardous site. A laser located remotely from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer. 10 figs.

  6. Mobile inductively coupled plasma system

    DOEpatents

    D'Silva, Arthur P.; Jaselskis, Edward J.

    1999-03-30

    A system for sampling and analyzing a material located at a hazardous site. A laser located remote from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer.

  7. Orientation of the water moiety in CF4-H2O

    NASA Astrophysics Data System (ADS)

    Evangelisti, Luca; Feng, Gang; Gou, Qian; Guidetti, Gloria; Caminati, Walther

    2012-12-01

    The rotational spectrum of CF4-H217O has been investigated by pulsed jet Fourier transform microwave spectroscopy. A symmetric top effective rotational spectrum has been observed, similarly to the case of the parent species (W. Caminati, A. Maris, A. Dell'Erba, P.G. Favero, Angew. Chem. Int. Ed. 45 (2006) 6711). The experimental value of the 17O χaa quadrupole coupling constant, 0.54(1) MHz, allows to determine the average value of the angle between the C2 axis of H2O and the C⋯O line, β = 24°.

  8. Effective decay time of CF4 secondary scintillation

    NASA Astrophysics Data System (ADS)

    Margato, L. M. S.; Morozov, A.; Fraga, M. M. F. R.; Pereira, L.; Fraga, F. A. F.

    2013-07-01

    We report on the time evolution of CF4 secondary scintillation in the pressure range from 1 to 5 bar. Two types of MSGC plates were used for generation of the secondary scintillation in electron avalanches. Time spectra of the scintillation were recorded using several broadband and interference filters in the wavelength range from 220 to 800 nm. The visible emission (450-800 nm) shows a mono-exponential profile with a decay time of ~ 15 ns. The UV emission (220-450 nm) exhibits two components. The fast component has an effective decay time ranging from ~ 2 ns (1 bar) to ~ 10 ns (3-5 bar), while the slow component shows a decay time of ~ 40 ns. The slow component accounts for not more than 10% of the integrated UV emission intensity.

  9. Coupling of Plasmas and Liquids

    NASA Astrophysics Data System (ADS)

    Lindsay, Alexander David

    Plasma-liquids have exciting applications to several important socioeconomic areas, including agriculture, water treatment, and medicine. To realize their application potential, the basic physical and chemical phenomena of plasma-liquid systems must be better understood. Additionally, system designs must be optimized in order to maximize fluxes of critical plasma species to the liquid phase. With objectives to increase understanding of these systems and optimize their applications, we have performed both comprehensive modeling and experimental work. To date, models of plasma-liquids have focused on configurations where diffusion is the dominant transport process in both gas and liquid phases. However, convection plays a key role in many popular plasma source designs, including jets, corona discharges, and torches. In this dissertation, we model momentum, heat, and neutral species mass transfer in a convection-dominated system based on a corona discharge. We show that evaporative cooling produced by gas-phase convection can lead to a significant difference between gas and liquid phase bulk temperatures. Additionally, convection induced in the liquid phase by the gas phase flow substantially increases interfacial mass transfer of hydrophobic species like NO and NO2. Finally, liquid kinetic modeling suggests that concentrations of highly reactive species like OH and ONOOH are several orders of magnitude higher at the interface than in the solution bulk. Subsequent modeling has focused on coupling discharge physics with species transport at and through the interface. An assumption commonly seen in the literature is that interfacial loss coefficients of charged species like electrons are equal to unity. However, there is no experimental evidence to either deny or support this assumption. Without knowing the true interfacial behavior of electrons, we have explored the effects on key plasma-liquid variables of varying interfacial parameters like the electron and energy

  10. Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas.

    PubMed

    Li, Yang; Wang, Cong; Yao, Zhao; Kim, Hong-Ki; Kim, Nam-Young

    2014-01-01

    In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF4/O2, C4F8/O2 and SF6/O2) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF6/O2 due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF4/O2 and C4F8/O2. Low-volatile C-F compound etching byproducts from C4F8/O2 were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF6/O2, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology.

  11. Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas

    PubMed Central

    2014-01-01

    In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF4/O2, C4F8/O2 and SF6/O2) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF6/O2 due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF4/O2 and C4F8/O2. Low-volatile C-F compound etching byproducts from C4F8/O2 were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF6/O2, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology. PMID:25278821

  12. Satellites of Xe transitions induced by infrared active vibrational modes of CF4 and C2F6 molecules.

    PubMed

    Alekseev, Vadim A; Schwentner, Nikolaus

    2011-07-28

    Absorption and luminescence excitation spectra of Xe/CF(4) mixtures were studied in the vacuum UV region at high resolution using tunable synchrotron radiation. Pressure-broadened resonance bands and bands associated with dipole-forbidden states of the Xe atom due to collision-induced breakdown of the optical selection rules are reported. The spectra display in addition numerous satellite bands corresponding to transitions to vibrationally excited states of a Xe-CF(4) collisional complex. These satellites are located at energies of Xe atom transition increased by one quantum energy in the IR active v(3) vibrational mode of CF(4) (v(3) = 1281 cm(-1)). Satellites of both resonance and dipole-forbidden transitions were observed. Satellites of low lying resonance states are spectrally broad bands closely resembling in shape their parent pressure-broadened resonance bands. In contrast, satellites of dipole-forbidden states and of high lying resonance states are spectrally narrow bands (FWHM ∼10 cm(-1)). The satellites of dipole-forbidden states are orders of magnitude stronger than transitions to their parent states due to collision-induced breakdown of the optical selection rules. These satellites are attributed to a coupling of dipole-forbidden and resonance states induced by the electric field of the transient CF(4) (v(3) = 0 ↔ v(3) = 1) dipole. Similar satellites are present in spectra of Xe/C(2)F(6) mixtures where these bands are induced by the IR active v(10) mode of C(2)F(6). Transitions to vibrationally excited states of Xe-CF(4)(C(2)F(6)) collision pairs were also observed in two-photon LIF spectra.

  13. Global Analysis of Several Bands of the CF_4 Molecule

    NASA Astrophysics Data System (ADS)

    Carlos, Mickaël; Gruson, Océane; Boudon, Vincent; Georges, Robert; Pirali, Olivier; Asselin, Pierre

    2016-06-01

    Carbon tetrafluoride is a powerful greenhouse gas, mainly of anthropogenic origin. Its absorption spectrum is, however, still badly modeled, especially for hot bands in the strongly absorbing ν_3 region. To overcome this problem, we have undertaken a systematic study of all the lower rovibrational transitions of this molecule. In particular, new far-infrared spectra recorded at the SOLEIL Synchrotron facility give access to bands implying the ``forbidden'' modes ν_1 and ν_2 which have only been investigated previously thanks to stimulated Raman spectroscopy, that is with a lower accuracy and much less data. Combined with the previous analyses performed in our group, we thus report here a new global fit of line positions of CF_4 by considering several transitions altogether: ν_2, 2ν_2-ν_2, ν_4, 2ν_4, ν_3 and ν_3-2ν_2. This gives a consistent set of molecular parameters that will be of great help for the analysis of hot bands like ν_3+ν_2-ν_2. A second separate global fit including the ν_1, ν_1-ν_4 and 2ν_1-ν_1 bands will also be presented. V. Boudon, D. Bermejo, R. Z. Martinez, J. Raman Spectrosc. 44, 731?738 (2013). V. Boudon, J. Mitchell, A. Domanskaya, C. Maul, R; Georges, A. Benidar, W. G. Harter, Mol. Phys. 109, 17--18 (2011)

  14. Increase of Stratospheric Carbon Tetrafluoride (CF4) Based on ATMOS Observations from Space

    NASA Technical Reports Server (NTRS)

    Zander, R.; Solomon, S.; Mahieu, E.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.; Abrams, M. C.; Chang, A. Y.; Michelsen, H. A.; Newchurch, M. J.; Stiller, G. P.

    1996-01-01

    Stratospheric volume mixing ratio profiles of carbon tetrafluoride, CF4, obtained with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the ATLAS (Atmospheric Laboratory for Applications and Science) -3 mission of 1994 are reported. Overall the profiles are nearly constant over the altitude range 20 to 50 km, indicative of the very long lifetime of CF4 in the atmosphere. In comparison to the stratospheric values of CF4 inferred from the ATMOS/Spacelab 3 mission of 1985, the 1994 concentrations are consistent with an exponential increase of (1.6 +/- 0.6)% yr(exp -1). This increase is discussed with regard to previous results and likely sources of CF4 at the ground. Further, it is shown that simultaneous measurements of N2O and CF4 provide a means of constraining the lower limit of the atmospheric lifetime of CF4 at least 2,300 years, two sigma.

  15. Ionosphere-magnetosphere coupling. I - Thermal plasma

    NASA Technical Reports Server (NTRS)

    Chappell, C. R.

    1975-01-01

    The complex interaction of the cold plasma of the plasmasphere and ionosphere with the hot plasma of the ring current and the plasma sheet is studied. It is seen that a coupling, probably through wave particle interactions, exists which seems to have a strong influence on the temperature of the plasma of the outer plasmasphere and on the detailed dynamics of the bulge region, especially the formation of detached plasma regions or plasma tails. Also, there is evidence that the outer plasmasphere may display very high temperatures, and that detached plasma regions are closely associated with ring current injections.

  16. Driving frequency fluctuations in pulsed capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Poulose, John; Goeckner, Matthew; Shannon, Steven; Coumou, David; Overzet, Lawrence

    2017-09-01

    We report time resolved measurements of the RF current, voltage and complex impedance for pulsed plasmas through electropositive (Ar) and electronegative (CF4, O2) gases and gas mixtures. In addition, we report measurements of the effective frequency versus time at various locations within the RF circuitry. The frequency is found to fluctuate away from that sourced by the RF generator when the plasma re-ignites. Plasma re-ignition induces abrupt impedance changes due to the re-formation of the plasma sheath and bulk. These fast changes in the plasma impedance cause the measured changes in the voltage and current frequencies. As a result, the frequency of the RF power at the plasma electrodes was found to be as much as 250 kHz different from that being sourced by the RF generator for short periods of time. These frequency fluctuations are of particular interest to the application of frequency tuned matching networks.

  17. Weak Wave Coupling Through Plasma Inhomogeneity

    NASA Astrophysics Data System (ADS)

    Swanson, D. G.

    1998-11-01

    Some effects of linear wave coupling due to effects of plasma inhomogeneity are well known through the process of mode conversion(D. G. Swanson, Theory of Mode Conversion and Tunneling in Inhomogenous Plasmas), (John Wiley & Sons, New York, 1998).. Another type of resonant coupling in a periodically inhomogeneous plasma has been recently found(V. A. Svidzinski and D. G. Swanson, Physics of Plasmas series 5), 486 (1998)., but any two waves will generally be coupled if the plasma is inhomogeneous, although the coupling may be weak. If the wavelengths are close, nearly all of the energy in one mode may be transferred to the other mode over a distance that depends on the coupling strength. The coupling strength depends on gradients of the plasma parameters. This means that the coupling may occur over an extended region in space, but that substantial amounts of wave energy may be transferred to a wave traditionally thought to be independent. Low-frequency Alfvén waves are shown to be a good example of this type of coupling.

  18. Circuit Model for Capacitive Coupling in Inductively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Watanabe, M.; Shaw, D. M.; Collins, G. J.; Sugai, H.

    1998-10-01

    A crude circuit model has been developed to illustrate and account for capacitive coupling between the rf coil and the bulk plasma in a stove top inductively coupled plasma source. The circuit model is composed of three levels of capacitance: the dielectric window capacitance, sheath capacitance contiguous to the dielectric window, and the chamber to ground sheath capacitance. The model is verified by quantitative comparison with the measured rf plasma potential in the bulk plasma body, plasma feedstock gas (argon) pressures below 2 mTorr. At higher pressures above 5 mTorr, the measured results diverge from the circuit model due to the transition from a spatially uniform electron density throughout the bulk plasma at pressures less than 2 mTorr to a less spatially uniform electron density at pressures above 5 mTorr.

  19. Langmuir Probe Distortions and Probe Compensation in an Inductively Coupled Plasma

    NASA Technical Reports Server (NTRS)

    Ji, J. S.; Cappelli, M. A.; Kim, J. S.; Rao, M. V. V. S.; Sharma, S. P.

    1999-01-01

    In many RF discharges, Langmuir probe measurements are usually made against a background of sinusoidal (and not so sinusoidal) fluctuations in the plasma parameters such as the plasma potential (Vp), the electron number density (ne), and the electron temperature (Te). The compensation of sinusoidal fluctuations in Vp has been extensively studied and is relatively well understood. Less attention has been paid to the possible distortions introduced by small fluctuations in plasma density and/or plasma temperature, which may arise in the sheath and pre-sheath regions of RF discharges. Here, we present the results of a model simulation of probe characteristics subject to fluctuations in both Vp and ne. The modeling of probe distortion due to possible fluctuations in Te is less straightforward. A comparison is presented of calculations with experimental measurements using a compensated and uncompensated Langmuir probe in an inductively coupled GEC reference cell plasma, operating on Ar and Ar/CF4 mixtures. The plasma parameters determined from the compensated probe characteristics are compared to previous measurements of others made in similar discharges, and to our own measurements of the average electron density derived from electrical impedance measurements.

  20. Evidence for crustal degassing of CF4 and SF6 in Mojave Desert groundwaters

    USGS Publications Warehouse

    Deeds, D.A.; Vollmer, M.K.; Kulongoski, J.T.; Miller, B.R.; Muhle, J.; Harth, C.M.; Izbicki, J.A.; Hilton, David R.; Weiss, R.F.

    2008-01-01

    Dissolved tetrafluoromethane (CF4) and sulfur hexafluoride (SF6) concentrations were measured in groundwater samples from the Eastern Morongo Basin (EMB) and Mojave River Basin (MRB) located in the southern Mojave Desert, California. Both CF4 and SF6 are supersaturated with respect to equilibrium with the preindustrial atmosphere at the recharge temperatures and elevations of the Mojave Desert. These observations provide the first in situ evidence for a flux of CF4 from the lithosphere. A gradual basin-wide enhancement in dissolved CF4 and SF6 concentrations with groundwater age is consistent with release of these gases during weathering of the surrounding granitic alluvium. Dissolved CF4 and SF6 concentrations in these groundwaters also contain a deeper crustal component associated with a lithospheric flux entering the EMB and MRB through the underlying basement. The crustal flux of CF4, but not of SF6, is enhanced in the vicinity of local active fault systems due to release of crustal fluids during episodic fracture events driven by local tectonic activity. When fluxes of CF4 and SF6 into Mojave Desert groundwaters are extrapolated to the global scale they are consistent, within large uncertainties, with the fluxes required to sustain the preindustrial atmospheric abundances of CF4 and SF6. ?? 2007 Elsevier Ltd. All rights reserved.

  1. Ignition delay of a pulsed inductively coupled plasma (ICP) in tandem with an auxiliary ICP

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Sridhar, Shyam; Donnelly, Vincent M.; Economou, Demetre J.

    2015-12-01

    Plasma ignition delays were observed in a ‘main’ inductively coupled plasma (ICP), in tandem with an ‘auxiliary’ ICP. The Faraday-shielded ICPs were separated by a grounded metal grid. Power (13.56 MHz) to the main ICP was pulsed with a frequency of 1 kHz, while the auxiliary ICP was operated in continuous wave (cw) mode. In chlorine plasmas, ignition delay was observed for duty cycles greater than 60% and, in contrast to expectation, the delay was longer with increasing duty cycle up to ~99.5%. The ignition delay could be varied by changing the auxiliary and/or main ICP power. Langmuir probe measurements provided the temporal evolution of electron temperature, and electron and positive ion densities. These measurements revealed that the plasma was ignited shortly after the decaying positive ion density (n +), in the afterglow of the main ICP, reached the density ({{n}+},\\text{aux} ) prevailing when only the auxiliary ICP was powered. At that time, production of electrons began to dominate their loss in the main ICP, due to hot electron injection from the auxiliary ICP. As a result, {{n}\\text{e}} increased from a value below {{n}\\text{e,\\text{aux}}} , improving inductive power coupling efficiency, further increasing plasma density leading to plasma ignition. Plasma ignition delay occurred when the afterglow of the pulsed plasma was not long enough for the ion density to reach {{n}+},\\text{aux} during the afterglow. Besides Cl2, plasma ignition delays were also observed in other electronegative gases (SF6, CF4/O2 and O2) but not in an electropositive gas (Ar).

  2. Inductively coupled plasma source for VASIMR engine

    NASA Astrophysics Data System (ADS)

    Godyak, V. A.; Smolyakov, A. I.; Sydorenko, D. Y.; Sagdeev, R. Z.; Krasheninnikov, S. I.; Shevchenko, V. I.

    2004-11-01

    Various devices for plasma production differ in the way of plasma coupling to the electrical energy source. Power losses in the chain from the AC power line to the power deposited into the electrons are the most important for the overall efficiency of the plasma source while the losses to ionization, radiation and walls are typically very similar and do not depend on a mechanism of the electron interaction with the electromagnetic field. Inductively coupled plasma (ICP) discharges with ferromagnetic cores, seems to be the most suitable candidate for a primary plasma source for VASIMR engine. Such commercial ICPs have coupling efficiency up to 98% (99% in laboratory devices). Combined with compact and efficient (90-95%) rf power converters operating at f < 1 MHz, it will allow to achieve high overall efficiency of plasma production and reduce the energy cost of the ion in the first stage plasma source. An important advantage of such sources is the ability to continuously work in a wide dynamic range (two orders of magnitude) of plasma density contrary to e.g. helicon sources where efficient operation is possible only on certain discrete modes (and plasma density) with discontinuous transitions between them.

  3. Description and preliminary calibration results for the Langley hypersonic CF4 tunnel

    NASA Technical Reports Server (NTRS)

    Midden, R. E.; Miller, C. G.

    1978-01-01

    A detailed description of the hypersonic CF4 tunnel is presented along with discussion of the basic components, instrumentation, and operating procedure. Operational experience with the CF4 reclaimer and lead-bath heater is discussed. Comparison of measured and predicted shock detachment distance on a sphere and pressure distributions measured on a sharp leading-edge flat plate revealed the absence of significant flow nonuniformity and lent creditability to predicted free stream flow conditions. The economic operation of this facility centers about the CF4 reclaimer, which was designed to operate at an efficiency of 90 to 95 percent. A number of modifications were made to the reclaimer system to improve its performance, and presently, the system reclaims approximately 75 percent of the test gas. Even with current budgetary constraints, this efficiency permits the CF4 tunnel to be operated as a viable research wind tunnel.

  4. Diffusive Mixing in Strongly Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Diaw, Abdourahmane; Murillo, Michael

    2016-10-01

    A multispecies hydrodynamic model based on moments of the Born-Bogolyubov-Green-Kirkwood-Yvon (BBGKY) hierarchy is developed for physical conditions relevant to astrophysical plasmas. The modified transport equations incorporate strong correlations through a density functional theory closure, while fluctuations enters through a mixture BGK operator. This model extends the usual Burgers equations for a dilute gas to strongly coupled and isothermal plasmas mixtures. The diffusive currents for these strongly coupled plasmas is self-consistently derived. The settling of impurities and its impact on cooling of white dwarfs and neutron stars can be greatly affected by strong Coulomb coupling, which we show can be quantified using the direct-correlation function. This work was supported by the Air Force Office of Scientific Research (Grant No. FA9550-12-1-0344).

  5. Ionization Potential Depression in Strongly Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Wark, Justin; Ciricosta, Orlando; Vinko, Sam; Crowley, Basil

    2013-10-01

    The focusing of the output of 4th generation femtosecond X-ray sources to ultra-high intensities has enabled the creation of hot (close to 200-eV) aluminum plasmas at exactly solid density. Tuning of the X-ray FEL energy that produces the plasma, and observation of the subsequent K- α fluorescence from the highly charged ions allows direct measurements of the K-edges, and hence ionization potential depression (IPD). The results of these experiments show far higher depressions than those predicted by the frequently-used Stewart-Pyatt model, but appear to be in contradiction with laser-plasma experimental data at similar densities, but with hotter, less strongly-coupled plasmas. We present here new calculations of the IPD, both ab initio and analytic, and discuss the relevance of the coupling parameter to the IPD. We further explore what constitutes our understanding of the physics of IPD, and how it should be modelled.

  6. Collisionless Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton

    2016-10-01

    The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space phenomena, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these rarified environments, collective electromagnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collisionless coupling mechanisms in a reproducible laboratory setting, the present research jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA to study the super-Alfvénic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field induction probes. Large Doppler shifts detected in a He II ion spectral line directly indicate initial ambient ion acceleration transverse to both the debris plasma flow and the background magnetic field, indicative of a fundamental process known as Larmor coupling. Characterization of the laser-produced debris plasma via a radiation-hydrodynamics code permits an explicit calculation of the laminar electric field in the framework of a ``hybrid'' model (kinetic ions, charge-neutralizing massless fluid electrons), thus allowing for a simulation of the initial response of a distribution of He II test ions. A synthetic Doppler-shifted spectrum constructed from the simulated velocity distribution of the accelerated test ions excellently reproduces the spectroscopic measurements, confirming the role of Larmor coupling in the debris-ambient interaction.

  7. Starter for inductively coupled plasma tube

    DOEpatents

    Hull, Donald E.; Bieniewski, Thomas M.

    1988-01-01

    A starter assembly is provided for use with an inductively coupled plasma (ICP) tube to reliably initate a plasma at internal pressures above about 30 microns. A conductive probe is inserted within the inductor coil about the tube and insulated from the tube shield assembly. A capacitive circuit is arranged for momentarily connecting a high voltage radio-frequency generator to the probe while simultaneously energizing the coil. When the plasma is initiated the probe is disconnected from the generator and electrically connected to the shield assembly for operation.

  8. Starter for inductively coupled plasma tube

    DOEpatents

    Hull, D.E.; Bieniewski, T.M.

    1988-08-23

    A starter assembly is provided for use with an inductively coupled plasma (ICP) tube to reliably initiate a plasma at internal pressures above about 30 microns. A conductive probe is inserted within the inductor coil about the tube and insulated from the tube shield assembly. A capacitive circuit is arranged for momentarily connecting a high voltage radio-frequency generator to the probe while simultaneously energizing the coil. When the plasma is initiated the probe is disconnected from the generator and electrically connected to the shield assembly for operation. 1 fig.

  9. Coupling between electron plasma waves in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Everett, M. J.; Lal, A.; Clayton, C. E.; Mori, W. B.; Joshi, C.; Johnston, T. W.

    1996-05-01

    A Lagrangian fluid model (cold plasma, fixed ions) is developed for analyzing the coupling between electron plasma waves. This model shows that a small wave number electron plasma wave (ω2,k2) will strongly affect a large wave number electron plasma wave (ω1,k1), transferring its energy into daughter waves or sidebands at (ω1+nω2,k1+nk2) in the lab frame. The accuracy of the model is checked via particle-in-cell simulations, which confirm that the energy in the mode at (ω1,k1) can be completely transferred to the sidebands at (ω1+nω2,k1+nk2) by the presence of the electron plasma mode at (ω2,k2). Conclusive experimental evidence for the generation of daughter waves via this coupling is then presented using time- and wave number-resolved spectra of the light from a probe laser coherently Thomson scattered by the electron plasma waves generated by the interaction of a two-frequency CO2 laser with a plasma.

  10. BOOK REVIEW: Physics of Strongly Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Kraeft, Wolf-Dietrich

    2007-07-01

    Strongly coupled plasmas (or non-ideal plasmas) are multi-component charged many-particle systems, in which the mean value of the potential energy of the system is of the same order as or even higher than the mean value of the kinetic energy. The constituents are electrons, ions, atoms and molecules. Dusty (or complex) plasmas contain still mesoscopic (multiply charged) particles. In such systems, the effects of strong coupling (non-ideality) lead to considerable deviations of physical properties from the corresponding properties of ideal plasmas, i.e., of plasmas in which the mean kinetic energy is essentially larger than the mean potential energy. For instance, bound state energies become density dependent and vanish at higher densities (Mott effect) due to the interaction of the pair with the surrounding particles. Non-ideal plasmas are of interest both for general scientific reasons (including, for example, astrophysical questions), and for technical applications such as inertially confined fusion. In spite of great efforts both experimentally and theoretically, satisfactory information on the physical properties of strongly coupled plasmas is not at hand for any temperature and density. For example, the theoretical description of non-ideal plasmas is possible only at low densities/high temperatures and at extremely high densities (high degeneracy). For intermediate degeneracy, however, numerical experiments have to fill the gap. Experiments are difficult in the region of `warm dense matter'. The monograph tries to present the state of the art concerning both theoretical and experimental attempts. It mainly includes results of the work perfomed in famous Russian laboratories in recent decades. After outlining basic concepts (chapter 1), the generation of plasmas is considered (chapter 2, chapter 3). Questions of partial (chapter 4) and full ionization (chapter 5) are discussed including Mott transition and Wigner crystallization. Electrical and optical

  11. Atmospheric observations for quantifying emissions of point-source synthetic greenhouse gases (CF4, NF3 and HFC-23)

    NASA Astrophysics Data System (ADS)

    Arnold, Tim; Manning, Alistair J.; Li, Shanlan; Kim, Jooil; Park, Sunyoung; Fraser, Paul J.; Mitrevski, Blagoj; Steele, L. Paul; Krummel, Paul B.; Mühle, Jens; Weiss, Ray F.

    2016-04-01

    The fluorinated species carbon tetrafluoride (CF4; PFC-14), nitrogen trifluoride (NF3) and trifluoromethane (CHF3; HFC-23) are potent greenhouse gases with 100-year global warming potentials of 6,630, 16,100 and 12,400, respectively. Unlike the majority of CFC-replacement compounds that are emitted from fugitive and mobile emission sources, these gases are largely emitted from large single point sources - semiconductor manufacturing facilities (all three), aluminium smelting plants (CF4) and chlorodifluoromethane factories (HFC-23). In this work we show the potential for atmospheric measurements to understand regional sources of these gases and to highlight emission 'hotspots'. We target our analysis on measurements from two Advanced Global Atmospheric Gases Experiment (AGAGE) long term monitoring sites that are particularly sensitive to regional emissions of these gases: Gosan on Jeju Island in the Republic of Korea and Cape Grim on Tasmania in Australia. These sites measure CF4, NF3 and HFC-23 alongside a suite of greenhouse and stratospheric ozone depleting gases every two hours using automated in situ gas-chromatography mass-spectrometry instrumentation. We couple each measurement to an analysis of air history using the regional atmospheric transport model NAME (Numerical Atmospheric dispersion Modelling Environment) driven by 3D meteorology from the Met Office's Unified Model, and use a Bayesian inverse method (InTEM - Inversion Technique for Emission Modelling) to calculate yearly emission changes over a decade (2005-2015) at high spatial resolution. At present these gases make a small contribution to global radiative forcing, however, given that their impact could rise significantly and that point sources of such gases can be mitigated, atmospheric monitoring could be an important tool for aiding emissions reduction policy.

  12. Enhanced laser beam coupling to a plasma

    DOEpatents

    Steiger, Arno D.; Woods, Cornelius H.

    1976-01-01

    Density perturbations are induced in a heated plasma by means of a pair of oppositely directed, polarized laser beams of the same frequency. The wavelength of the density perturbations is equal to one half the wavelength of the laser beams. A third laser beam is linearly polarized and directed at the perturbed plasma along a line that is perpendicular to the direction of the two opposed beams. The electric field of the third beam is oriented to lie in the plane containing the three beams. The frequency of the third beam is chosen to cause it to interact resonantly with the plasma density perturbations, thereby efficiently coupling the energy of the third beam to the plasma.

  13. An atmospheric photochemical source of the persistent greenhouse gas CF4

    NASA Astrophysics Data System (ADS)

    Jubb, Aaron M.; McGillen, Max R.; Portmann, Robert W.; Daniel, John S.; Burkholder, James B.

    2015-11-01

    A previously uncharacterized atmospheric source of the persistent greenhouse gas tetrafluoromethane, CF4, has been identified in the UV photolysis of trifluoroacetyl fluoride, CF3C(O)F, which is a degradation product of several halocarbons currently present in the atmosphere. CF4 quantum yields in the photolysis of CF3C(O)F were measured at 193, 214, 228, and 248 nm, wavelengths relevant to stratospheric photolysis, to be (75.3 ± 1) × 10-4, (23.7 ± 0.4) × 10-4, (6.6 ± 0.2) × 10-4, and ≤0.4 × 10-4, respectively. A 2-D atmospheric model was used to estimate the contribution of the photochemical source to the global CF4 budget. The atmospheric photochemical production of CF4 from CF3CH2F (HFC-134a), CF3CHFCl (HCFC-124), and CF3CCl2F (CFC-114a) per molecule emitted was calculated to be (1-2.5) × 10-5, 1.0 × 10-4, and 2.8 × 10-3, respectively. Although CF4 photochemical production was found to be relatively minor at the present time, the identified mechanism demonstrates that long-lived products with potential climate impacts can be formed from the atmospheric breakdown of shorter-lived source gases.

  14. Computational analysis and preliminary redesign of the nozzle contour of the Langley hypersonic CF4 tunnel

    NASA Technical Reports Server (NTRS)

    Thompson, R. A.; Sutton, Kenneth

    1987-01-01

    A computational analysis, modification, and preliminary redesign study was performed on the nozzle contour of the Langley Hypersonic CF4 Tunnel. This study showed that the existing nozzle was contoured incorrectly for the design operating condition, and this error was shown to produce the measured disturbances in the exit flow field. A modified contour was designed for the current nozzle downstream of the maximum turning point that would provide a uniform exit flow. New nozzle contours were also designed for an exit Mach number and Reynolds number combination which matches that attainable in the Langley 20-Inch Mach 6 Tunnel. Two nozzle contours were designed: one having the same exit radius but a larger mass flow rate than that of the existing CF4 Tunnel, and the other having the same mass flow rate but a smaller exit radius than that of the existing CF4 Tunnel.

  15. Terrestrial Sources of Perfluorinated Gases: Excess CF4 and SF6 in Mojave Desert Groundwaters

    NASA Astrophysics Data System (ADS)

    Deeds, D. A.; Vollmer, M. K.; Kulongoski, J. T.; Miller, B. R.; Hilton, D. R.; Izbicki, J. A.; Harth, C. M.; Weiss, R. F.

    2004-12-01

    The recent discovery of perfluorinated gases in fluid inclusions of granites and fluorites suggests a geologic source for the estimated 40 parts-per-trillion (ppt) of tetrafluoromethane (CF4) and <0.006 ppt of sulfur hexafluoride (SF6) in the preindustrial atmosphere. The accumulation of these gases in groundwaters with long residence times enables the detection of even small emissions from the surrounding aquifer material. We have measured high concentrations of CF4 and SF6 in groundwaters from the Mojave Desert, California. Dissolved SF6 was extracted by a purge and trap technique and analyzed by gas chromatography with electron capture detection. Dissolved CF4 was sampled by headspace extraction, using liquid helium to cryofocus the analytes prior to injection into the Medusa gas chromatograph/quadrupole mass spectrometer analytical system. Current precisions and accuracies for these measurements are on the order of 2% for both gases. Initial measurements of dissolved CF4 concentrations range from ˜0.05 to ˜1.5 pmol kg-1, about 5 to 15 times higher than expected for water in equilibrium with the preindustrial atmosphere at the local temperature and altitude of the recharge site. SF6 concentrations range from ˜0.3 to ˜16 fmol kg-1, up to several thousand times higher than expected for air-saturated water. Taking into account the large uncertainties in the estimated preindustrial atmospheric concentration of SF6, and in the estimated atmospheric lifetimes of both SF6 and CF4, the ratio of their excess abundances in Mojave Desert groundwaters agrees within an order of magnitude with the estimated ratio of natural fluxes required to sustain their preindustrial atmospheric concentrations. Relationships among dissolved CF4 and SF6 concentrations and the other geochemical properties of the aquifer, including groundwater residence times (ages), helium abundances and isotopic ratios, and fluoride concentrations will be presented.

  16. Design Considerations in Capacitively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Song, Sang-Heon; Ventzek, Peter; Ranjan, Alok

    2015-11-01

    Microelectronics industry has driven transistor feature size scaling from 10-6 m to 10-9 m during the past 50 years, which is often referred to as Moore's law. It cannot be overstated that today's information technology would not have been so successful without plasma material processing. One of the major plasma sources for the microelectronics fabrication is capacitively coupled plasmas (CCPs). The CCP reactor has been intensively studied and developed for the deposition and etching of different films on the silicon wafer. As the feature size gets to around 10 nm, the requirement for the process uniformity is less than 1-2 nm across the wafer (300 mm). In order to achieve the desired uniformity, the hardware design should be as precise as possible before the fine tuning of process condition is applied to make it even better. In doing this procedure, the computer simulation can save a significant amount of resources such as time and money which are critical in the semiconductor business. In this presentation, we compare plasma properties using a 2-dimensional plasma hydrodynamics model for different kinds of design factors that can affect the plasma uniformity. The parameters studied in this presentation include chamber accessing port, pumping port, focus ring around wafer substrate, and the geometry of electrodes of CCP.

  17. Slope and amplitude asymmetry effects on low frequency capacitively coupled carbon tetrafluoride plasmas

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Korolov, I.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Johnson, E.; Booth, J.-P.

    2016-04-01

    We report investigations of capacitively coupled carbon tetrafluoride (CF4) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.

  18. Ion Energy Distributions and their Relative Abundance in Inductively Coupled Plasmas

    NASA Technical Reports Server (NTRS)

    Kim, J. S.; Rao, M. V. V. S.; Cappelli, M. A.; Sharma, S. P.; Arnold, James O. (Technical Monitor)

    1998-01-01

    Study of kinetics of ions and neutrals produced in high density inductively coupled plasma (ICP) discharges is of great importance for achieving a high degree of plasma assisted deposition and etching. In this paper, we present the ion energy distributions (IEDs) of various ions arriving at the grounded lower electrode. The ions were energy as well as mass analyzed by a combination of electrostatic analyzer-quadrupole mass spectrometer for pure Ar and CF4/Ar mixtures. The measurements have been made at gas pressures ranging from 30 to 100 mTorr. In addition, the IEDs were measured when the wafer-supporting electrode was also rf-powered and the effect of the self-bias was observed in the energy distributions of ions. The shapes of the IEDs are discussed an related to the sheath properties and measured electrical waveforms, as a function of pressure and applied power. Relative ion intensities were obtained by integration of each ion kinetic energy distribution function over its energy range.

  19. Parametric investigations of striations in electronegative capacitively coupled radio-frequency plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Xin; Schungel, Edmund; Korolov, Ihor; Donko, Zoltan; Schulze, Julian; Wang, You-Nian

    2016-09-01

    Striated structures in light emission have been observed by Phase Resolved Optical Emission Spectroscopy (PROES) and analyzed based on particle-based kinetic simulations in capacitively coupled rf CF4 plasmas. On this basis, we conduct a systematic study on the effects of external parameters on the striated structure by PROES and particle-based kinetic simulations. Our results exhibit that at 100 Pa pressure and 300 V voltage amplitude striations generally occur within a certain driving frequency range, i.e., between 2 MHz and 18 MHz, and the distance between the ion density maxima decreases with rising driving frequency. A mode discharge transition from the ``drift-ambipolar'' into ``striation'' mode could be observed by increasing the pressure or rf voltage. The reasons for these observations are further understood by the analytical solution of a simply model of the ion-ion plasma. This work has been supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 11335004 and 11405018).

  20. Inductively coupled plasmas at low driving frequencies

    NASA Astrophysics Data System (ADS)

    Kolobov, Vladimir I.; Godyak, Valery A.

    2017-07-01

    We discuss the peculiarities of inductively coupled plasma (ICP) at low driving frequencies. The ratio of electric to magnetic field, | E/(cB)| , decreases with decreasing frequency according to Faraday’s law—higher magnetic fields are required to induce the same electric field at lower frequencies. We point out that the ratio of | E/(cB)| can be non-uniform in space depending on primary coil configuration and the presence of ferromagnetic materials. In this paper, we consider examples of low-frequency ICPs with negligibly small magnetic fields in plasma. The disparity of time scales for ion transport and the electron energy relaxation results in nonlinear plasma dynamics at low frequencies. Numerical simulations demonstrate that at low frequencies, the presence of plasma has very little effect on spatial distributions of the electric and magnetic fields, which are determined solely by the coil geometry and by the presence of ferromagnetic cores. Simulations of plasma dynamics in ICP over a wide range of driving frequencies and gas pressures illustrate high-frequency, quasi-static and dynamic regimes of discharge operation and explain some trends observed in experiments.

  1. Plasma transport theory spanning weak to strong coupling

    SciTech Connect

    Daligault, Jérôme; Baalrud, Scott D.

    2015-06-29

    We describe some of the most striking characteristics of particle transport in strongly coupled plasmas across a wide range of Coulomb coupling strength. We then discuss the effective potential theory, which is an approximation that was recently developed to extend conventional weakly coupled plasma transport theory into the strongly coupled regime in a manner that is practical to evaluate efficiently.

  2. Titanium oxidation by rf inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Valencia-Alvarado, R.; de la Piedad-Beneitez, A.; López-Callejas, R.; Barocio, S. R.; Mercado-Cabrera, A.; Peña-Eguiluz, R.; Muñoz-Castro, A. E.; Rodríguez-Méndez, B. G.; de la Rosa-Vázquez, J. M.

    2014-05-01

    The development of titanium dioxide (TiO2) films in the rutile and anatase phases is reported. The films have been obtained from an implantation/diffusion and sputtering process of commercially pure titanium targets, carried out in up to 500 W plasmas. The experimental outcome is of particular interest, in the case of anatase, for atmospheric pollution degradation by photocatalysis and, as to the rutile phase, for the production of biomaterials required by prosthesis and implants. The reactor employed consists in a cylindrical pyrex-like glass vessel inductively coupled to a 13.56 MHz RF source. The process takes place at a 5×10-2 mbar pressure with the target samples being biased from 0 to -3000 V DC. The anatase phase films were obtained from sputtering the titanium targets over glass and silicon electrically floated substrates placed 2 cm away from the target. The rutile phase was obtained by implantation/diffusion on targets at about 700 °C. The plasma was developed from a 4:1 argon/oxygen mixture for ~5 hour processing periods. The target temperature was controlled by means of the bias voltage and the plasma source power. The obtained anatase phases did not require annealing after the plasma oxidation process. The characterization of the film samples was conducted by means of x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy and Raman spectroscopy.

  3. Simulating strongly coupled plasmas at low temperatures

    NASA Astrophysics Data System (ADS)

    Bussmann, M.; Schramm, U.; Habs, D.

    2006-10-01

    Realistic molecular dynamics (MD) simulations of the particle dynamics in strongly coupled plasmas require the computation of the mutual Coulomb-force for each pair of charged particles if a correct treatment of long range correlations is required. For plasmas with N > 104 particles this requires a tremendous number of computational steps which can only be addressed using efficient parallel algorithms adopted to modern super-computers. We present a new versatile MD simulation code which can simulate the non-relativistic mutual Coulomb-interaction of a large number of charged particles in arbitrary external field configurations. A demanding application is the simulation of the complete dynamics of in-trap stopping of highly charged ions in a laser cooled plasma of N = 105 24Mg+ ions. We demonstrate that the simulation is capable of delivering results on stopping times and plasma dynamics under realistic conditions. The results suggest that this stopping scheme can compete with in-trap electron cooling and might be an alternative approach for delivering ultra cold highly charged ions for future trap-based experiments aiming for precision mass measurements of stable and radioactive nuclei.

  4. Strongly-coupled plasmas formed from laser-heated solids

    PubMed Central

    Lyon, M.; Bergeson, S. D.; Hart, G.; Murillo, M. S.

    2015-01-01

    We present an analysis of ion temperatures in laser-produced plasmas formed from solids with different initial lattice structures. We show that the equilibrium ion temperature is limited by a mismatch between the initial crystallographic configuration and the close-packed configuration of a strongly-coupled plasma, similar to experiments in ultracold neutral plasmas. We propose experiments to demonstrate and exploit this crystallographic heating in order to produce a strongly coupled plasma with a coupling parameter of several hundred. PMID:26503293

  5. Electrical Coupling Efficiency of Inductive Plasma Accelerators

    NASA Technical Reports Server (NTRS)

    Martin, Adam K.; Eskridge, Richard H.

    2005-01-01

    A single-stage pulsed inductive plasma accelerator is modeled as an inductive mass-driver. The plasma is treated as a rigid slug, which acts as the armature. The system is a transformer, with the drive coil serving as the primary and the slug as the secondary. We derive a set of coupled dynamic-circuit equations, which depend on five dimensionless coefficients, and on the functional form of the mutual inductance profile, M (z). For a given coil geometry, M (z) was determined experimentally and compared to the results of calculations carried out with QuickField. The equations are solved with various coefficient values, in order to determine the conditions that yield high efficiencies. It was found that the coupling efficiency can be quite high and likely scales with power, although this does not preclude operation at lower power with acceptable efficiency. The effect of an imbedded magnetic bias flux, as for the case of a plasmoid thruster, was also included in the calculations.

  6. Laser Plasma Coupling for High Temperature Hohlraums

    SciTech Connect

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  7. Electrical Coupling Efficiency of Inductive Plasma Accelerators

    NASA Technical Reports Server (NTRS)

    Martin, Adam K.; Eskridge, Richard H.

    2005-01-01

    A single-stage pulsed inductive plasma accelerator is modeled as an inductive mass-driver. The plasma is treated as a rigid slug, which acts as the armature. The system is a transformer, with the drive coil serving as the primary and the slug as the secondary. We derive a set of coupled dynamic-circuit equations, which depend on five dimensionless coefficients, and on the functional form of the mutual inductance profile, M (z). For a given coil geometry, M (z) was determined experimentally and compared to the results of calculations carried out with QuickField. The equations are solved with various coefficient values, in order to determine the conditions that yield high efficiencies. It was found that the coupling efficiency can be quite high and likely scales with power, although this does not preclude operation at lower power with acceptable efficiency. The effect of an imbedded magnetic bias flux, as for the case of a plasmoid thruster, was also included in the calculations.

  8. Instabilities in a capacitively coupled oxygen plasma

    SciTech Connect

    Küllig, C. Wegner, Th. Meichsner, J.

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  9. Interaction of O2 with CH4, CF4, and CCl4 by Molecular Beam Scattering Experiments and Theoretical Calculations.

    PubMed

    Cappelletti, David; Aquilanti, Vincenzo; Bartocci, Alessio; Nunzi, Francesca; Tarantelli, Francesco; Belpassi, Leonardo; Pirani, Fernando

    2016-07-14

    Gas phase collisions of O2 by CH4, CF4, and CCl4 have been investigated with the molecular beam technique by measuring both the integral cross section value, Q, and its dependence on the collision velocity, v. The adopted experimental conditions have been appropriate to resolve the oscillating "glory" pattern, a quantum interference effect controlled by the features of the intermolecular interaction, for all the three case studies. The analysis of the Q(v) data, performed by adopting a suitable representation of the intermolecular potential function, provided the basic features of the anisotropic potential energy surfaces at intermediate and large separation distances and information on the relative role of the physically relevant types of contributions to the global interaction. The present work demonstrates that while O2-CH4 and O2-CF4 are basically bound through the balance between size (Pauli) repulsion and dispersion attraction, an appreaciable intermolecular bond stabilization by charge transfer is operative in O2-CCl4. Ab initio calculations of the strength of the interaction, coupled with detailed analysis of electronic charge displacement promoted by the formation of the dimer, fully rationalizes the experimental findings. This investigation indicates that the interactions of O2, when averaged over its relative orientations, are similar to that of a noble gas (Ng), specifically Ar. We also show that the binding energy in the basic configurations of the prototypical Ng-CF4,CCl4 systems [ Cappelletti , D. ; Chem. Eur. J. 2015 , 21 , 6234 - 6240 ] can be reconstructed by using the interactions in Ng-F and Ng-Cl systems, previously characterized by molecular beam scattering experiments of state-selected halogen atom beams. This information is fundamental to approach the modeling of the weak intermolecular halogen bond. On the basis of the electronic polarizability, this also confirms [ Aquilanti , V. ; Angew. Chem., Int. Ed. 2005 , 44 , 2356 - 2360 ] that O2

  10. Measurement of the specific refractivities of CF4 and C2F6

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Goad, W. K.

    1980-01-01

    In order to relate the measured fringe shift of an interferometer to the density of a medium, the relation between density and refractive index, which is expressed by the specific refractivity, must be known. In the present paper, the specific refractivities of the wind tunnel test gases CF4 and C2F6 are determined in order to verify estimations based on the atomic refractivities of carbon and fluorine. A Twyman-Green two-beam interferometer with a 633-nm He-Ne laser light source was used to measure the specific refractivity as a function of fringe shift as the density of the gas was changed. Values of 0.122 and 0.131 cu cm/g were obtained for CF4 and C2F6 respectively at a temperature of 300 K, which are within 1% of the values computed from the atomic refractivities.

  11. Measurement of the specific refractivities of CF4 and C2F6

    NASA Astrophysics Data System (ADS)

    Burner, A. W.; Goad, W. K.

    1980-07-01

    In order to relate the measured fringe shift of an interferometer to the density of a medium, the relation between density and refractive index, which is expressed by the specific refractivity, must be known. In the present paper, the specific refractivities of the wind tunnel test gases CF4 and C2F6 are determined in order to verify estimations based on the atomic refractivities of carbon and fluorine. A Twyman-Green two-beam interferometer with a 633-nm He-Ne laser light source was used to measure the specific refractivity as a function of fringe shift as the density of the gas was changed. Values of 0.122 and 0.131 cu cm/g were obtained for CF4 and C2F6 respectively at a temperature of 300 K, which are within 1% of the values computed from the atomic refractivities.

  12. Striations in electronegative capacitively coupled radio-frequency plasmas: Effects of the pressure, voltage, and electrode gap

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Xin; Korolov, Ihor; Schüngel, Edmund; Wang, You-Nian; Donkó, Zoltán; Schulze, Julian

    2017-07-01

    Capacitively coupled radio-frequency (CCRF) CF4 plasmas have been found to exhibit a self-organized striated structure at operating conditions, where the plasma is strongly electronegative and the ion-ion plasma in the bulk region (largely composed of CF3+ and F- ions) resonates with the excitation frequency. In this work, we explore the effects of the gas pressure, the RF voltage, and the electrode gap on this striated structure by phase resolved optical emission spectroscopy and particle-in-cell/Monte Carlo collisions simulations. The measured electronic excitation patterns at different external parameters show a good general agreement with the spatio-temporal plots of the ionization rate obtained from the simulations. For a fixed driving frequency, the minima of the CF3+ or F- ion densities (between the density peaks in the bulk) are comparable and independent of other external parameters. However, the ion density maxima generally increase as a function of the pressure or RF voltage, leading to the enhanced spatial modulation of plasma parameters. The striation gap (defined as the distance between two ion density peaks) is approximately inversely proportional to the pressure, while it exhibits a weak dependence on the RF voltage and the electrode gap. A transition between the striated and non-striated modes can be observed by changing either the pressure or the RF voltage; for 13.56 and 18 MHz driving frequencies, we present a phase diagram as a function of the pressure and voltage amplitude parameters.

  13. Scintillation properties of N2 and CF4 and performances of a scintillating ionization chamber

    NASA Astrophysics Data System (ADS)

    Lehaut, G.; Salvador, S.; Fontbonne, J.-M.; Lecolley, F.-R.; Perronnel, J.; Vandamme, Ch.

    2015-10-01

    In this work, we studied the emission yields, decay times and coincidence resolving times (CRT) of two gases, nitrogen (N2) and tetrafluoromethane (CF4), used for particle detection in the context of fission products measurement. The set-up was made of an ionization chamber and two photomultiplier tubes (PMTs) placed front-to-front on each side of the active zone of the chamber. Using the photomultiplier tubes, the number of photoelectrons (phe) converted at the photocathodes from the scintillation processes in each gas was quantified and the scintillation time spectra were recorded. A scintillation emission yield of 24 phe MeV-1 with a decay time of τd = 2.5 ns in N2, and 225 phe MeV-1 with τd = 6.2 ns for CF4, has been measured. With our set-up, the coincidence resolving time (σ values) between the two PMTs have been measured using alpha particles at 1.4 ns and 0.34 ns for N2 and CF4, respectively.

  14. Hypersonic lateral and directional stability characteristics of aeroassist flight experiment configuration in air and CF4

    NASA Technical Reports Server (NTRS)

    Micol, John R.; Wells, William L.

    1993-01-01

    Hypersonic lateral and directional stability characteristics measured on a 60 deg half-angle elliptical cone, which was raked at an angle of 73 deg from the cone centerline and with an ellipsoid nose (ellipticity equal to 2.0 in the symmetry plane), are presented for angles of attack from -10 to 10 deg. The high normal-shock density ratio of a real gas was simulated by tests at a Mach number of 6 in air and CF4 (density ratio equal to 5.25 and 12.0, respectively). Tests were conducted in air at Mach 6 and 10 and in CF4 at Mach 6 to examine the effects of Mach number, Reynolds number, and normal-shock density ratio. Changes in Mach number from 6 to 10 in air or in Reynolds number by a factor of 4 at Mach 6 had a negligible effect on lateral and directional stability characteristics. Variations in normal-shock density ratio had a measurable effect on lateral and directional aerodynamic coefficients, but no significant effect on lateral and directional stability characteristics. Tests in air and CF4 indicated that the configuration was laterally and directionally stable through the test range of angle of attack.

  15. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, Donald E.; Bieniewski, Thomas M.

    1990-01-01

    A method for making fine power using an inductively coupled plasma. The method provides a gas-free environment, since the plasma is formed without using a gas. The starting material used in the method is in solid form.

  16. Experimental Observation and Computational Analysis of Striations in Electronegative Capacitively Coupled Radio-Frequency Plasmas.

    PubMed

    Liu, Yong-Xin; Schüngel, Edmund; Korolov, Ihor; Donkó, Zoltán; Wang, You-Nian; Schulze, Julian

    2016-06-24

    Self-organized spatial structures in the light emission from the ion-ion capacitive rf plasma of a strongly electronegative gas (CF_{4}) are observed experimentally for the first time. Their formation is analyzed and understood based on particle-based kinetic simulations. These "striations" are found to be generated by the resonance between the driving radio frequency and the eigenfrequency of the ion-ion plasma (derived from an analytical model) that establishes a modulation of the electric field, the ion densities, as well as the energy gain and loss processes of electrons in the plasma. The growth of the instability is followed by the numerical simulations.

  17. Gluon Bremsstrahlung in Weakly-Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Arnold, Peter

    2009-11-01

    I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≳10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q̂.

  18. Laser Ablation Inductively Coupled Plasma Mass Spectrometry

    PubMed Central

    Hutchinson, Robert W.; McLachlin, Katherine M.; Riquelme, Paloma; Haarer, Jan; Broichhausen, Christiane; Ritter, Uwe; Geissler, Edward K.; Hutchinson, James A.

    2015-01-01

    ABSTRACT New analytical techniques for multiparametric characterisation of individual cells are likely to reveal important information about the heterogeneity of immunological responses at the single-cell level. In this proof-of-principle study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied to the problem of concurrently detecting 24 lineage and activation markers expressed by human leucocytes. This approach was sufficiently sensitive and specific to identify subpopulations of isolated T, B, and natural killer cells. Leucocyte subsets were also accurately detected within unfractionated peripheral blood mononuclear cells preparations. Accordingly, we judge LA-ICP-MS to be a suitable method for assessing expression of multiple tissue antigens in solid-phase biological specimens, such as tissue sections, cytospins, or cells grown on slides. These results augur well for future development of LA-ICP-MS–based bioimaging instruments for general users. PMID:27500232

  19. Hydrogen atom kinetics in capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Nunomura, Shota; Katayama, Hirotaka; Yoshida, Isao

    2017-05-01

    Hydrogen (H) atom kinetics has been investigated in capacitively coupled very high frequency (VHF) discharges at powers of 16-780 mW cm-2 and H2 gas pressures of 0.1-2 Torr. The H atom density has been measured using vacuum ultra violet absorption spectroscopy (VUVAS) with a micro-discharge hollow cathode lamp as a VUV light source. The measurements have been performed in two different electrode configurations of discharges: conventional parallel-plate diode and triode with an intermediate mesh electrode. We find that in the triode configuration, the H atom density is strongly reduced across the mesh electrode. The H atom density varies from ˜1012 cm-3 to ˜1010 cm-3 by crossing the mesh with 0.2 mm in thickness and 36% in aperture ratio. The fluid model simulations for VHF discharge plasmas have been performed to study the H atom generation, diffusion and recombination kinetics. The simulations suggest that H atoms are generated in the bulk plasma, by the electron impact dissociation (e + H2 \\to e + 2H) and the ion-molecule reaction (H2 + + H2 \\to {{{H}}}3+ + H). The diffusion of H atoms is strongly limited by a mesh electrode, and thus the mesh geometry influences the spatial distribution of the H atoms. The loss of H atoms is dominated by the surface recombination.

  20. Space charge dynamics Of CF4 fluorinated LDPE samples from different fluorination conditions and their DC conductivities

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Li, Ziyun; Chen, George; Chen, Qiang; Li, Shengtao

    2017-07-01

    Taking advantage of plasma technology using mixing gas CF4/H2, a fluorination process was performed on LDPE samples in the present paper. Different exposure times and discharge voltage levels were applied to produce four different types of samples. It has been found that after fluorination, space charge injection is obviously suppressed. And with longer fluorination times and higher discharge voltage, injected homocharges are reduced. By employing x-ray photoelectron spectroscopy, new chemical groups of C-F bindings are confirmed to be introduced by fluorination process of the plasma treatment. The charge suppression effect can be explained as: surface traps introduced by fluorination will reduce the interface field at both electrodes. Moreover, for fluorinated samples, heterocharge emerges obviously under 30 kV \\text{m}{{\\text{m}}-1} , which are considered as charges ionized from degradation products of etching and/or lower weight molecular specifies. Through the conductivity measurements also performed at 30 kV \\text{m}{{\\text{m}}-1} , it is found that, for the fluorinated samples with the better charge blocking effect, the conductivity is lowered. However, the conductivity of the fluorinated sample with the lightest degree of fluorination is found to be higher than that of normal samples.

  1. Measuring nanopore size from the spin-lattice relaxation of CF4 gas

    PubMed Central

    Kuethe, Dean O.; Montaño, Rebecca; Pietraß, Tanja

    2007-01-01

    The NMR 19F spin-lattice relaxation time constant T1 for CF4 gas is dominated by spin–rotation interaction, which is mediated by the molecular collision frequency. When confined to pores of approximately the same size or smaller than the bulk gas mean free path, additional collisions of molecules with the pore walls should substantially change T1. To develop a method for measuring the surface/volume ratio S/V by measuring how T1 changes with confinement, we prepared samples of known S/V from fumed silica of known mass-specific surface area and compressed to varying degrees into cylinders of known volume. We then measured T1 for CF4 in these samples at varying pressures, and developed mathematical models for the change in T1 to fit the data. Even though CF4 has a critical temperature below room temperature, we found that its density in pores was greater than that of the bulk gas and that it was necessary to take this absorption into account. We modeled adsorption in two ways, by assuming that the gas condenses on the pore walls, and by assuming that gas in a region near the wall is denser than the bulk gas because of a simplified attractive potential. Both models suggested the same two-parameter formula, to which we added a third parameter to successfully fit the data and thus achieved a rapid, precise way to measure S/V from the increase in T1 due to confinement in pores. PMID:17400493

  2. Micro-Hole and Strip Plate (MHSP) operation in CF4

    NASA Astrophysics Data System (ADS)

    Natal da Luz, H.; Mir, J. A.; Veloso, J. F. C. A.; dos Santos, J. M. F.; Rhodes, N. J.; Schooneveld, E. M.

    2007-09-01

    The Micro-Hole and Strip Plate (MHSP) is a hybrid electron multiplier which combines the working principles of a Gas Electron Multiplier (GEM) and a Micro-Strip Gas Counter (MSGC). The compact double stage electron multiplication processes found in the MHSP enables the realisation of higher gas gain than the lone GEM operation. Thermal neutron detection using gas detectors involves the use of He3 gas with another suitable stopping gas, operated at elevated pressure to confine the products of the neutron- He3 reaction. It is, however, well known that the gain of GEMs drops too sharply with increasing chamber pressure. We have pursued experimental work using the MHSP to infer the upper limits of thermal neutron position resolution. The stopping gas used during the present studies was Tetrafluoromethane (CF4) chosen due to its low X-ray and γ-ray efficiency, requiring only 2.6 bar to yield a position resolution of 1 mm. In the present studies, systematic measurements were taken to establish the gain versus CF4 pressure characteristics of the MHSP, in the 1 to 2.65 bar range. These studies demonstrated that it was possible to sustain gains above 104 and 300 with pressures of 1 and 2.65 bar, respectively. The advantage of having two multiplication stages in the MHSP separated by only few tens of microns, results in a less pronounced gain reduction with pressure, presenting higher gains than single or multiple GEMs. The energy resolution at 1 bar was 29% FWHM for the 5.9 keV Mn Kα line from a Fe55 source, which is a typical value for micro-patterned gas detectors operating in CF4.

  3. The appearance energy of CF+3 from CF4: ion/molecule reactions related to the thermochemistry of CF+3

    NASA Astrophysics Data System (ADS)

    Fisher, Ellen R.; Armentrout, P. B.

    1990-11-01

    Guided ion beam mass spectrometry studies designed to measure the appearance energy for CF+3 from CF4 are reported. In contrast to a previous observation, we find that there is no flouride transfer equilibrium between CF+3. Rather, the thresholds for formation of CF+3 from reaction of ground state Kr+ (2P) with CF4 and from collision-induced dissociation of CF+3 by Xe are used to establish AE(CF+3/CF4).Both results are in good agreement although the former experiment yields a more precise value, namely 14.24 ± 0.07 eV.

  4. Identification of the V3 vibration-rotation band of CF4 in balloon-borne infrared solar spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, D. G.; Murcray, F. J.; Cook, G. R.; Van Allen, J. W.; Bonomo, F. S.; Blatherwick, R. D.

    1979-01-01

    Infrared solar spectra in the 850 to 1350/cm region, at 0.02/cm resolution, were obtained during a balloon flight made on 27 October 1978 from Alamogordo, New Mexico. Analysis of the 1275-1290/cm region indicates that the atmospheric absorption lines of CH4, N2O, H2O, HNO3 and CO2 near 1283/cm are super-imposed on a broader absorption feature which we interpret as due to the V3 band of CF4. Fine structure of CF4 is also identified. Preliminary estimates from the sunset spectra show approximately 75 pptv CF4 near 25 km.

  5. Controlled MoS₂ layer etching using CF₄ plasma.

    PubMed

    Jeon, Min Hwan; Ahn, Chisung; Kim, HyeongU; Kim, Kyong Nam; LiN, Tai Zhe; Qin, Hongyi; Kim, Yeongseok; Lee, Sehan; Kim, Taesung; Yeom, Geun Young

    2015-09-04

    A few-layered molybdenum disulfide (MoS2) thin film grown by plasma enhanced chemical vapor deposition was etched using a CF4 inductively coupled plasma, and the possibility of controlling the MoS2 layer thickness to a monolayer of MoS2 over a large area substrate was investigated. In addition, damage and contamination of the remaining MoS2 layer surface after etching and a possible method for film recovery was also investigated. The results from Raman spectroscopy and atomic force microscopy showed that one monolayer of MoS2 was etched by exposure to a CF4 plasma for 20 s after an initial incubation time of 20 s, i.e., the number of MoS2 layers could be controlled by exposure to the CF4 plasma for a certain processing time. However, XPS data showed that exposure to CF4 plasma induced a certain amount of damage and contamination by fluorine of the remaining MoS2 surface. After exposure to a H2S plasma for more than 10 min, the damage and fluorine contamination of the etched MoS2 surface could be effectively removed.

  6. Effect of the gas contamination on CF4 primary and secondary scintillation

    NASA Astrophysics Data System (ADS)

    Margato, L. M. S.; Morozov, A.; Pereira, L.; Fraga, M. M. F. R.; Fraga, F. A. F.

    2012-12-01

    The effect of gas contamination on light emission properties of CF4 is presented. The study was performed in the UV (220-450 nm) and visible (450-800 nm) wavelength ranges and the relative light emission intensity and effective decay times were measured. Gas contamination effects, as well as the effect of controllable addition of small quantities of gas admixtures were investigated for both the primary and secondary scintillation. The primary ionization was produced by alpha-particles from an Am-241 alpha source, and MSGC plates were used for electron multiplication and secondary light production. Two types of commercial gas purifiers were tested.

  7. Thermophysical properties of CF4/O2 and SF6/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Hohm, U.; Balabanova, E.; Barton, D.

    2016-03-01

    Fitting formulae are presented for the calculation of the second interaction virial coefficients, mixture viscosities and binary diffusion coefficients for CF4/O2 and SF6/O2 gas mixtures in the temperature range between 200 K and 1000 K. The data recommended are obtained from the isotropic (n-6) Lennard-Jones intermolecular interaction potentials of the pure substances by using the Hohm-Zarkova-Damyanova mixing rules. In general, a good agreement is observed between our results and the experimental and theoretical data found in the literature.

  8. Formation of negative ions by electron impact on SiF4 and CF4

    NASA Technical Reports Server (NTRS)

    Iga, I.; Rao, M. V. V. S.; Srivastava, S. K.; Nogueira, J. C.

    1992-01-01

    First measurements of cross sections for the formation of negative ions by electron attachment to SiF4 and CF4 are reported for an electron impact energy range of 0 to 50 eV. The energies at which the various ions appear and the positions at which the ionization efficiency curves peak have been obtained and compared with previous measurements. Thermochemical data have been used to predict and identify the various channels of dissociation. Cross sections for the production of ion pairs through the process of polar dissociation have also been measured.

  9. Formation of negative ions by electron impact on SiF4 and CF4

    NASA Technical Reports Server (NTRS)

    Iga, I.; Rao, M. V. V. S.; Srivastava, S. K.; Nogueira, J. C.

    1992-01-01

    First measurements of cross sections for the formation of negative ions by electron attachment to SiF4 and CF4 are reported for an electron impact energy range of 0 to 50 eV. The energies at which the various ions appear and the positions at which the ionization efficiency curves peak have been obtained and compared with previous measurements. Thermochemical data have been used to predict and identify the various channels of dissociation. Cross sections for the production of ion pairs through the process of polar dissociation have also been measured.

  10. Vibrationally resolved photoionization dynamics of CF4 in the D 2A1 state

    NASA Astrophysics Data System (ADS)

    Das, Aloke; Scott Miller, J.; Poliakoff, E. D.; Lucchese, R. R.; Bozek, John D.

    2007-07-01

    Vibrationally resolved photoelectron spectroscopy of the CF4+ (DA12) state is studied for the first time over an extended energy range, 26.5⩽hν ⩽50eV. It is found that the energy dependence of the totally symmetric stretching vibration is qualitatively different from all of the other vibrational modes. Moreover, the vibrational branching ratio curves for all of the symmetry forbidden vibrations are nearly identical. Qualitative arguments are used to show that it is likely that at least two shape resonances are present in the continuum, and that their characteristics, such as energy dependence and spatial localization, are distinctly different.

  11. Measurement of the Specific Refractivities of CF4 and C2F6

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Goad, W. K.

    1977-01-01

    In order to relate the measured fringe shift of an interferometer to density, the relation between density rho and refractive index n must be known. For gases where the refractive index is close to unity, this relation between density and refractive index is very closely approximated by (n - 1) = K rho where K is the specific refractivity, or the Gladstone-Dale constant. The specific refractivity, which is weakly dependent on wavelength and temperature, is readily available for a number of common test gases such as N2 and air. For more unique test gases such as CF4 and C2F6 for which refractive index data at optical wavelengths is not readily available, the constants can be estimated from the atomic refractivities of carbon and fluorine. In order to verify this estimation, a two-beam interferometer was used to experimentally determine the specific refractivities of CF4 and C2F6. This data was required for holographic interferometric measurements made at the Langley Hypersonic CF4 Tunnel. A Twyman-Green interferometer with a He-Ne laser light source of vacuum wavelength lambda equal to 633 nm was used to measure the constants. One beam of the two-beam interferometer passed through an optical cell of known inside length l which could be evacuated and slowly filled with the test gas to a density of 7.2 kg/cu m for CF4 or 5.7 kg/cu m for C2F6. If the refractive index (and hence density) is constant along the optical path through the cell, the fringe shift M and density change Delta rho are related M = 2Kl Delta rho/lambda for the double pass interferometer. Thus K can be determined by measuring the fringe shift as the density is changed. The output of a photodiode used to detect the fringe shift was recorded on a strip chart recorder. The rate of pressure increase of the test gas in the cell was controlled such that the fringes shifted at a rate of 0.5 to 1 fringe per sec. The pressure in the test cell was measured with a high accuracy quartz crystal pressure

  12. Shock waves in strongly coupled plasmas

    SciTech Connect

    Khlebnikov, Sergei; Kruczenski, Martin; Michalogiorgakis, Georgios

    2010-12-15

    Shock waves are supersonic disturbances propagating in a fluid and giving rise to dissipation and drag. Weak shocks, i.e., those of small amplitude, can be well described within the hydrodynamic approximation. On the other hand, strong shocks are discontinuous within hydrodynamics and therefore probe the microscopics of the theory. In this paper, we consider the case of the strongly coupled N=4 plasma whose microscopic description, applicable for scales smaller than the inverse temperature, is given in terms of gravity in an asymptotically AdS{sub 5} space. In the gravity approximation, weak and strong shocks should be described by smooth metrics with no discontinuities. For weak shocks, we find the dual metric in a derivative expansion, and for strong shocks we use linearized gravity to find the exponential tail that determines the width of the shock. In particular, we find that, when the velocity of the fluid relative to the shock approaches the speed of light v{yields}1 the penetration depth l scales as l{approx}(1-v{sup 2}){sup 1/4}. We compare the results with second-order hydrodynamics and the Israel-Stewart approximation. Although they all agree in the hydrodynamic regime of weak shocks, we show that there is not even qualitative agreement for strong shocks. For the gravity side, the existence of shock waves implies that there are disturbances of constant shape propagating on the horizon of the dual black holes.

  13. Coupled Langmuir oscillations in 2-dimensional quantum plasmas

    SciTech Connect

    Akbari-Moghanjoughi, M.

    2014-03-15

    In this work, we present a hydrodynamic model to study the coupled quantum electron plasma oscillations (QEPO) for two dimensional (2D) degenerate plasmas, which incorporates all the essential quantum ingredients such as the statistical degeneracy pressure, electron-exchange, and electron quantum diffraction effect. Effects of diverse physical aspects like the electronic band-dispersion effect, the electron exchange-correlations and the quantum Bohm-potential as well as other important plasma parameters such as the coupling parameter (plasma separation) and the plasma electron number-densities on the linear response of the coupled system are investigated. By studying three different 2D plasma coupling types, namely, graphene-graphene, graphene-metalfilm, and metalfilm-metalfilm coupling configurations, it is remarked that the collective quantum effects can influence the coupled modes quite differently, depending on the type of the plasma configuration. It is also found that the slow and fast QEPO frequency modes respond very differently to the change in plasma parameters. Current findings can help in understanding of the coupled density oscillations in multilayer graphene, graphene-based heterojunctions, or nanofabricated integrated circuits.

  14. Rotational inelastic scattering of He-atoms at HF-, HCl-, CF4-, SF6-, C2H6- and C2F6-molecules

    NASA Astrophysics Data System (ADS)

    Frick, J.

    1984-05-01

    The measurement of total differential scattering cross sections and energy loss spectra up to scattering angles of 80 deg for the collision systems He-HCl, -HF, -C2H6, -C2F6, -CF4, -SF6 and Ne-SF6 is described. The collision energies being 69 to 95 meV, the only inelastic precess is the transfer of rotational energy. The measuring device contains two crossed molecular beams in a vetical-plane configuration and separates single rotational transfers of two-atomic molecules models. Scattering calculations for the two-atomic targets were performed, with the exact close-coupling method.

  15. Plasma sweeper to control the coupling of RF power to a magnetically confined plasma

    DOEpatents

    Motley, Robert W.; Glanz, James

    1985-01-01

    A device for coupling RF power (a plasma sweeper) from a phased waveguide array for introducing RF power to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the phased waveguide array; and a potential source coupled to the electrode for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  16. Shear viscosities of photons in strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Yang, Di-Lun; Müller, Berndt

    2016-09-01

    We investigate the shear viscosity of thermalized photons in the quark gluon plasma (QGP) at weak coupling and N = 4 super Yang-Mills plasma (SYMP) at both strong and weak couplings. We find that the shear viscosity due to the photon-parton scattering up to the leading order of electromagnetic coupling is suppressed when the coupling of the QGP/SYMP is increased, which stems from the blue-shift of the thermal-photon spectrum at strong coupling. In addition, the shear viscosity rapidly increases near the deconfinement transition in a phenomenological model analogous to the QGP.

  17. Molecular dynamics study of di-CF4 based reverse micelles in supercritical CO2.

    PubMed

    Liu, Bing; Tang, Xinpeng; Fang, Wenjing; Li, Xiaoqi; Zhang, Jun; Zhang, Zhiliang; Shen, Yue; Yan, Youguo; Sun, Xiaoli; He, Jianying

    2016-10-26

    Reverse micelles (RMs) in supercritical CO2 (scCO2) are promising alternatives for organic solvents, especially when both polar and non-polar components are involved. Fluorinated surfactants, particularly double-chain fluorocarbon surfactants, are able to form well-structured RMs in scCO2. The inherent self-assembly mechanisms of surfactants in scCO2 are still subject to discussion. In this study, molecular dynamics simulations are performed to investigate the self-aggregation behavior of di-CF4 based RMs in scCO2, and stable and spherical RMs are formed. The dynamics process and the self-assembly structure in the RMs reveal a three-step mechanism to form the RMs, that is, small RMs, rod-like RMs and fusion of the rod-like RMs. Hydrogen-bonds between headgroups and water molecules, and salt bridges linking Na(+) ions, headgroups and water molecules enhance the interfacial packing efficiency of the surfactant. The results show that di-CF4 molecules have a high surfactant coverage at the RM interface, implying a high CO2-philicity. This mainly results from bending of the short chain (C-COO-CH2-(CF2)3-CF3) due to the flexible carboxyl group. The microscopic insight provided in this study is helpful in understanding surfactant self-assembly phenomena and designing new CO2-philic surfactants.

  18. Numerical velocity distributions of positive and negative ions incident on a wafer in a pulsed 2f-CCP in CF_4/Ar for SiO2 etching

    NASA Astrophysics Data System (ADS)

    Yagisawa, T.; Maeshige, K.; Makabe, T.

    2002-10-01

    Charging damage during plasma etching of insulator will be still interesting issue with further decreasing the size of elements of ULSI. Recently, we reported the experimental evidence of the reduction of charging voltage during etching by using a pulsed two-frequency capacitively coupled plasma(2f-CCP)(T.Fujita and T.Makabe; Plasma Sources Sci.Technol.11),142 (2002) T.Ohmori et al ; submitted . In this work, we will focus on the charging free plasma etching in a pulsed 2f-CCP system with rf sources used for sustaining a high density plasma at VHF (100MHz) and biasing a wafer at high energy positive ion at LF (1MHz). A particle trace method (Monte Carlo simulation) is used to estimate a time-dependent ion velocity distribution, on the basis of the 2D-t plasma structure predicted by the RCT model(K.Maeshige,G.Washio,T.Yagisawa,T.Makabe;J.Appl.Phys. 91),9494(2002) (T.Makabe and K.Maeshige; Appl.Surf.Sci. 192),176(2002). Typical velocity distribution with non-linear time-dependence, modulated at low frequency bias power at 1MHz or 500kHz is shown. The characteristics of the impact energy and angle, which act as the element to reduce charges accumulated inside the hole/trench in SiO2 with high aspect ratio, are discussed for positive and negative ions in a pulsed 2f-CCP in CF_4(5%)/Ar.

  19. Synchronization between two coupled direct current glow discharge plasma sources

    SciTech Connect

    Chaubey, Neeraj; Mukherjee, S.; Sen, A.; Sekar Iyengar, A. N.

    2015-02-15

    Experimental results on the nonlinear dynamics of two coupled glow discharge plasma sources are presented. A variety of nonlinear phenomena including frequency synchronization and frequency pulling are observed as the coupling strength is varied. Numerical solutions of a model representation of the experiment consisting of two coupled asymmetric Van der Pol type equations are found to be in good agreement with the observed results.

  20. Collisional Thermalization in Strongly Coupled Ultracold Neutral Plasmas

    DTIC Science & Technology

    2017-01-25

    and powerful diagnostics adopted from ultracold atomic physics experiments. Because of this unique collection of characteristics, ions in ultracold...Transport in Strongly Coupled Systems with Ultracold Plasmas," Atomic Physics Seminar, Yale University, New Haven, CT (12/16). ``From Ultracold Plasmas to...ultracold neutral plasmas, which are formed by photoionizing laser cooled atoms . These are the coldest neutral plasmas every created, and they allow

  1. Plasma diagnostics and plasma-surface interactions in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Titus, Monica Joy

    The semiconductor industry's continued trend of manufacturing device features on the nanometer scale requires increased plasma processing control and improved understanding of plasma characteristics and plasma-surface interactions. This dissertation presents a series of experimental results for focus studies conducted in an inductively coupled plasma (ICP) system. First novel "on-wafer" diagnostic tools are characterized and related to plasma characteristics. Second, plasma-polymer interactions are characterized as a function of plasma species and processing parameters. Complementary simulations accompany each focus study to supplement experimental findings. Wafer heating mechanisms in inductively coupled molecular gas plasmas are explored with PlasmaTemp(TM), a novel "on-wafer" diagnostic tool. Experimental wafer measurements are obtained with the PlasmaTemp(TM) wafer processed in argon (Ar) and argon-oxygen (Ar/O2) mixed plasmas. Wafer heating mechanisms were determined by combining the experimental measurements with a 3-dimensional heat transfer model of the wafer. Comparisons between pure Ar and Ar/O2 plasmas demonstrate that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. Thermal heat conduction from the neutral gas and O-atom recombination on wafer surface can contribute as much as 60% to wafer heating under conditions of low-energy ion bombardment in molecular plasmas. Measurements of a second novel "on-wafer" diagnostic sensor, the PlasmaVolt(TM), were tested and validated in the ICP system for Ar plasmas varying in power and pressure. Sensor measurements were interpreted with a numerical sheath simulation and comparison to scaling laws derived from the inhomogeneous sheath model. The study demonstrates sensor measurements are proportional to the RF-current through the sheath and the scaling is a function of sheath impedance. PlasmaVolt(TM) sensor measurements are proportional to the

  2. Dissociation limit and dissociation dynamic of CF4(+): application of threshold photoelectron-photoion coincidence velocity imaging.

    PubMed

    Tang, Xiaofeng; Zhou, Xiaoguo; Wu, Manman; Gao, Zhi; Liu, Shilin; Liu, Fuyi; Shan, Xiaobin; Sheng, Liusi

    2013-03-07

    Dissociation of internal energy selected CF4(+) ions in an excitation energy range of 15.40-19.60 eV has been investigated using threshold photoelectron-photoion coincidence (TPEPICO) velocity imaging. Only CF3(+) fragment ions are observed in coincident mass spectra, indicating all the X(2)T1, A(2)T2, and B(2)E ionic states of CF4(+) are fully dissociative. Both kinetic energy released distribution (KERD) and angular distribution in dissociation of CF4(+) ions have been derived from three-dimensional TPEPICO time-sliced images. A parallel distribution of CF3(+) fragments along the polarization vector of photon is observed for dissociation of CF4(+) ions in all the low-lying electronic states. With the aid of F-loss potential energy curves, dissociation mechanisms of CF4(+) ions in these electronic states have been proposed. CF4(+) ions in both X(2)T1 and A(2)T2 states directly dissociate to CF3(+) and F fragments along the repulsive C-F coordinate, while a two-step dissociation mechanism is suggested for B(2)E state: CF4(+)(B(2)E) ion first converts to the lower A(2)T2 state via internal conversion, then dissociates to CF3(+) and F fragments along the steep A(2)T2 potential energy surface. In addition, an adiabatic appearance potential of AP0(CF3(+)∕CF4) has also been established to be 14.71 ± 0.02 eV, which is very consistent with the recent calculated values.

  3. Effects of 3D microlens transfer into fused silica substrate by CF4/O2 dry etching

    NASA Astrophysics Data System (ADS)

    Grigaliūnas, Viktoras; Jucius, Dalius; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Sakaliūnienė, Jolita; Abakevičienė, Brigita; Kopustinskas, Vitoldas; Smetona, Saulius; Tamulevičius, Sigitas

    2017-01-01

    Nowadays, 3D microoptical elements find a variety of applications from light emitting diodes and household appliances to precise medical endoscopes. Such elements, fabricated in a fused silica substrate by combining 3D e-beam patterning and dry etching, can be used as a mold for the high throughput replication in polymeric materials by UV nanoimprint technique. Flexible and precise control of 3D shape in the resist layer can be achieved by e-beam patterning, but it is also very important to know peculiarities of 3D pattern transfer from resist layer into the fused silica substrate. This paper reports on the effects of PMMA 3D microlens pattern transfer into fused silica substrate by CF4/O2 dry etching. It is demonstrated that etching rate ratio between PMMA and fused silica changes during plasma treatment. Thus, the resulting shape of transferred 3D profile is different from the shape in PMMA and this variation must be assessed during the design phase.

  4. Electron power absorption dynamics in capacitive radio frequency discharges driven by tailored voltage waveforms in CF4

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Berger, B.; Schüngel, E.; Korolov, I.; Derzsi, A.; Bruneau, B.; Johnson, E.; Lafleur, T.; O'Connell, D.; Koepke, M.; Gans, T.; Booth, J.-P.; Donkó, Z.; Schulze, J.

    2016-08-01

    The power absorption dynamics of electrons and the electrical asymmetry effect in capacitive radio-frequency plasmas operated in CF4 and driven by tailored voltage waveforms are investigated experimentally in combination with kinetic simulations. The driving voltage waveforms are generated as a superposition of multiple consecutive harmonics of the fundamental frequency of 13.56 MHz. Peaks/valleys and sawtooth waveforms are used to study the effects of amplitude and slope asymmetries of the driving voltage waveform on the electron dynamics and the generation of a DC self-bias in an electronegative plasma at different pressures. Compared to electropositive discharges, we observe strongly different effects and unique power absorption dynamics. At high pressures and high electronegativities, the discharge is found to operate in the drift-ambipolar (DA) heating mode. A dominant excitation/ionization maximum is observed during sheath collapse at the edge of the sheath which collapses fastest. High negative-ion densities are observed inside this sheath region, while electrons are confined for part of the RF period in a potential well formed by the ambipolar electric field at this sheath edge and the collapsed (floating potential) sheath at the electrode. For specific driving voltage waveforms, the plasma becomes divided spatially into two different halves of strongly different electronegativity. This asymmetry can be reversed electrically by inverting the driving waveform. For sawtooth waveforms, the discharge asymmetry and the sign of the DC self-bias are found to reverse as the pressure is increased, due to a transition of the electron heating mode from the α-mode to the DA-mode. These effects are interpreted with the aid of the simulation results.

  5. Ideal gas behavior of a strongly coupled complex (dusty) plasma.

    PubMed

    Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry

    2013-07-05

    In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas.

  6. Visco-elastic effects in strongly coupled dusty plasmas

    SciTech Connect

    Bandyopadhyay, P.; Prasad, G.; Sen, A.; Kaw, P. K.

    2008-09-07

    We report on experimental evidence of visco-elastic effects in a strongly coupled dusty plasma through investigations of the propagation characteristics of low frequency dust acoustic waves and by excitations of transverse shear waves in a DC discharge Argon plasma.

  7. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, Donald E.; Bieniewski, Thomas M.

    1989-01-01

    A method for coating surfaces or implanting ions in an object using an inductively coupled plasma. The method provides a gas-free environment, since the plasma is formed without using a gas. The coating material or implantation material is intitially in solid form.

  8. Multi-fluid simulation models for inductively coupled plasma sources

    NASA Astrophysics Data System (ADS)

    Kundrapu, Madhusudhan; Veitzer, Seth A.; Stoltz, Peter H.; Beckwith, Kristian R. C.; Smith, Jonathan

    2017-08-01

    A numerical simulation model for Inductively Coupled Plasma (ICP) sources and its implementation in the USim fluid-plasma software is presented. The electric field from the external antenna is solved using the vector potential equation with a variable dielectric constant. Plasma generation and species transport are solved using a set of collisional multi-fluid equations in diffusion form. USim results are benchmarked with experiments from the literature. Density and temperature distributions show good agreement both qualitatively and quantitatively with the measurements.

  9. Ion-wave stabilization of an inductively coupled plasma

    SciTech Connect

    Camparo, J.C.; Mackay, R.

    2006-04-24

    Stabilization of the rf power driving an inductively coupled plasma (ICP) has implications for fields ranging from atomic clocks to analytical chemistry to illumination technology. Here, we demonstrate a technique in which the plasma itself acts as a probe of radio wave power, and provides a correction signal for active rf-power control. Our technique takes advantage of the resonant nature of forced ion waves in the plasma, and their observation in the ICP's optical emission.

  10. Local fields in strongly coupled plasmas

    SciTech Connect

    Pollock, E.L.; Weisheit, J.C.

    1984-06-01

    Computer simulation techniques and important static properties of plasma microfields are discussed. The relevant timescales are introduced for dynamical atomic problems, and some time-dependent properties of microfields are discussed. In the last two sections of the paper these results are applied to two problems relevant to the spectroscopy of dense plasmas: (1) broadening of spectral lines, and (2) screening in inelastic electron-ion collisions.

  11. Energy coupling to the plasma in repetitive nanosecond pulse discharges

    SciTech Connect

    Adamovich, Igor V.; Nishihara, Munetake; Choi, Inchul; Uddi, Mruthunjaya; Lempert, Walter R.

    2009-11-15

    A new analytic quasi-one-dimensional model of energy coupling to nanosecond pulse discharge plasmas in plane-to-plane geometry has been developed. The use of a one-dimensional approach is based on images of repetitively pulsed nanosecond discharge plasmas in dry air demonstrating that the plasma remains diffuse and uniform on a nanosecond time scale over a wide range of pressures. The model provides analytic expressions for the time-dependent electric field and electron density in the plasma, electric field in the sheath, sheath boundary location, and coupled pulse energy. The analytic model predictions are in very good agreement with numerical calculations. The model demonstrates that (i) the energy coupled to the plasma during an individual nanosecond discharge pulse is controlled primarily by the capacitance of the dielectric layers and by the breakdown voltage and (ii) the pulse energy coupled to the plasma during a burst of nanosecond pulses decreases as a function of the pulse number in the burst. This occurs primarily because of plasma temperature rise and resultant reduction in breakdown voltage, such that the coupled pulse energy varies approximately proportionally to the number density. Analytic expression for coupled pulse energy scaling has been incorporated into the air plasma chemistry model, validated previously by comparing with atomic oxygen number density measurements in nanosecond pulse discharges. The results of kinetic modeling using the modified air plasma chemistry model are compared with time-resolved temperature measurements in a repetitively pulsed nanosecond discharge in air, by emission spectroscopy, and purely rotational coherent anti-Stokes Raman spectroscopy showing good agreement.

  12. Coupled dust-lattice solitons in monolayer plasma crystals.

    PubMed

    Ivlev, A V; Zhdanov, S K; Morfill, G E

    2003-12-01

    Nonlinearly coupled dust-lattice (DL) waves in monolayer plasma crystals are studied theoretically. It is shown that the high-frequency transverse (vertical) oscillations can form localized wave envelopes--solitons coupled with "slow" longitudinal DL perturbations. Using the molecular dynamics simulations, the derived soliton solution is shown to be stable.

  13. Three-dimensional model of magnetized capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Kenney, Jason; Collins, Ken

    2009-05-01

    A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O2) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the E ×B drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the E ×B drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the E ×B drift. The E ×B drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the E ×B drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O2 plasma, the overall plasma is found to move in one direction due to the E ×B drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the E ×B drift direction.

  14. Three-dimensional model of magnetized capacitively coupled plasmas

    SciTech Connect

    Rauf, Shahid; Kenney, Jason; Collins, Ken

    2009-05-15

    A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O{sub 2}) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the ExB drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the ExB drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the ExB drift. The ExB drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the ExB drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O{sub 2} plasma, the overall plasma is found to move in one direction due to the ExB drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the ExB drift direction.

  15. Avr4 promotes Cf-4 receptor-like protein association with the BAK1/SERK3 receptor-like kinase to initiate receptor endocytosis and plant immunity.

    PubMed

    Postma, Jelle; Liebrand, Thomas W H; Bi, Guozhi; Evrard, Alexandre; Bye, Ruby R; Mbengue, Malick; Kuhn, Hannah; Joosten, Matthieu H A J; Robatzek, Silke

    2016-04-01

    The first layer of plant immunity is activated by cell surface receptor-like kinases (RLKs) and proteins (RLPs) that detect infectious pathogens. Constitutive interaction with the SUPPRESSOR OF BIR1 (SOBIR1) RLK contributes to RLP stability and kinase activity. As RLK activation requires transphosphorylation with a second associated RLK, it remains elusive how RLPs initiate downstream signaling. We employed live-cell imaging, gene silencing and coimmunoprecipitation to investigate the requirement of associated kinases for functioning and ligand-induced subcellular trafficking of Cf RLPs that mediate immunity of tomato against Cladosporium fulvum. Our research shows that after elicitation with matching effector ligands Avr4 and Avr9, BRI1-ASSOCIATED KINASE 1/SOMATIC EMBRYOGENESIS RECEPTOR KINASE 3 (BAK1/SERK3) associates with Cf-4 and Cf-9. BAK1/SERK3 is required for the effector-triggered hypersensitive response and resistance of tomato against C. fulvum. Furthermore, Cf-4 interacts with SOBIR1 at the plasma membrane and is recruited to late endosomes upon Avr4 trigger, also depending on BAK1/SERK3. These observations indicate that RLP-mediated resistance and endocytosis require ligand-induced recruitment of BAK1/SERK3, reminiscent of BAK1/SERK3 interaction and subcellular fate of the FLAGELLIN SENSING 2 (FLS2) RLK. This reveals that diverse classes of cell surface immune receptors share common requirements for initiation of resistance and endocytosis. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  16. Negative ion boundary layers in Inductively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Vitello, Peter

    1999-10-01

    Partially ionized plasmas at low neutral pressure and high plasma density may exhibit strong ion-ion coupling through space charge and Coulomb scattering effects. For electronegative plasmas this can lead to large scale irregularities in the ion density, temperature, and flux. In this regime, the force on ions due to ion-ion Coulomb scattering may dominate that from ion scattering with neutrals. This can lead to the formation of a negative ion boundary layer containing the bulk of the negative ions. Commercial Inductively Coupled Plasma reactors used in the semiconductor industry typically operate at low pressure and high plasma density. Simulations, including a detailed treatment of ion temperatures, are presented for a Chlorine discharge in the GEC reactor modified for Inductively Coupled operation. Results show that ion-ion coupling can induce large variations in the plasma, and that accurate modeling of spatial plasma structure should include these effects. This work was performed under the auspices of the U. S. Department of Energy at the Lawrence Livermore National Laboratory under contract W-7405-ENG-48.

  17. Solar terrestrial coupling through space plasma processes

    SciTech Connect

    Birn, J.

    2000-12-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project investigates plasma processes that govern the interaction between the solar wind, charged particles ejected from the sun, and the earth's magnetosphere, the region above the ionosphere governed by the terrestrial magnetic field. Primary regions of interest are the regions where different plasma populations interact with each other. These are regions of particularly dynamic plasma behavior, associated with magnetic flux and energy transfer and dynamic energy release. The investigations concerned charged particle transport and energization, and microscopic and macroscopic instabilities in the magnetosphere and adjacent regions. The approaches combined space data analysis with theory and computer simulations.

  18. Vibrational relaxation of S2(a1Δg) by collisions with SF6 and CF4

    NASA Astrophysics Data System (ADS)

    Tendo, Shogo; Tanimoto, Haruka; Uchiyama, Tohru; Goto, Hiroki; Hara, Ayano; Fujihara, Keigo; Kohguchi, Hiroshi; Yamasaki, Katsuyoshi

    2017-09-01

    Irradiation of the pulsed laser light at 248 nm to the gaseous mixture of OCS and He generated vibrationally excited S2 (a1Δg, v = 2 - 4) by the S(1D) + OCS reaction. A single vibrational level of S2 (a1Δg) was detected with laser-induced fluorescence (LIF) via the f1Δu -a1Δg transition. The rate coefficients for energy transfer from vibrational levels v = 2 and 3 of S2 (a1Δg) to SF6 and CF4 have been determined from the time-resolved LIF intensities recorded at varying pressures of SF6 and CF4. The reduced probability of energy transfer per collision derived from the rate coefficients enabled us to identify the ν4 mode of SF6 and CF4 as the energy-accepting vibration.

  19. Computational Implementation of a Coupled Plasma-Neutral Fluid Model

    NASA Astrophysics Data System (ADS)

    Vold, E. L.; Najmabadi, F.; Conn, R. W.

    1992-12-01

    This paper describes the computational transport of coupled plasma-neutral fluids in the edge region of a toroidally symmetric magnetic confinement device, with applications to the tokamak. The model couples neutral density in a diffusion approximation with a set of transport equations for the plasma including density, classical plasma parallel velocity, anomalous cross-field velocity, and ion and electron temperature equations. The plasma potential, gradient electric fields, drift velocity, and net poloidal velocity are computed as dependent quantities under the assumption of ambipolarity. The implementation is flexible to permit extension in the future to a fully coupled set of non-ambipolar momentum equations. The computational method incorporates sonic flow and particle recycling of ions and neutrals at the vessel boundary. A numerically generated orthogonal grid conforms to the poloidal magnetic flux surfaces. Power law differencing based on the SIMPLE relaxation method is modified to accomodate the compressible reactive plasma flow with a "semi-implicit" diffusion method. Residual corrections are applied to obtain a valid convergence to the steady state solution. Results are presented for a representative divertor tokamak in a high recycling regime, showing strongly peaked neutral and plasma densities near the divertor target. Solutions show large poloidal and radial gradients in the plasma density, potential, and temperatures. These findings may help to understand the strong turbulence experimentally observed in the plasma edge region of the tokamak.

  20. Structural properties of lithium atom under weakly coupled plasma environment

    NASA Astrophysics Data System (ADS)

    Dutta, S.; Saha, J. K.; Chandra, R.; Mukherjee, T. K.

    2016-04-01

    The Rayleigh-Ritz variational technique with a Hylleraas basis set is being tested for the first time to estimate the structural modifications of a lithium atom embedded in a weakly coupled plasma environment. The Debye-Huckel potential is used to mimic the weakly coupled plasma environment. The wave functions for both the helium-like lithium ion and the lithium atom are expanded in the explicitly correlated Hylleraas type basis set which fully takes care of the electron-electron correlation effect. Due to the continuum lowering under plasma environment, the ionization potential of the system gradually decreases leading to the destabilization of the atom. The excited states destabilize at a lower value of the plasma density. The estimated ionization potential agrees fairly well with the few available theoretical estimates. The variation of one and two particle moments, dielectric susceptibility and magnetic shielding constant, with respect to plasma density is also been discussed in detail.

  1. Structural properties of lithium atom under weakly coupled plasma environment

    SciTech Connect

    Dutta, S.; Saha, J. K.

    2016-04-15

    The Rayleigh-Ritz variational technique with a Hylleraas basis set is being tested for the first time to estimate the structural modifications of a lithium atom embedded in a weakly coupled plasma environment. The Debye-Huckel potential is used to mimic the weakly coupled plasma environment. The wave functions for both the helium-like lithium ion and the lithium atom are expanded in the explicitly correlated Hylleraas type basis set which fully takes care of the electron-electron correlation effect. Due to the continuum lowering under plasma environment, the ionization potential of the system gradually decreases leading to the destabilization of the atom. The excited states destabilize at a lower value of the plasma density. The estimated ionization potential agrees fairly well with the few available theoretical estimates. The variation of one and two particle moments, dielectric susceptibility and magnetic shielding constant, with respect to plasma density is also been discussed in detail.

  2. A conserved proline residue in Dothideomycete Avr4 effector proteins is required to trigger a Cf-4-dependent hypersensitive response.

    PubMed

    Mesarich, Carl H; Stergiopoulos, Ioannis; Beenen, Henriek G; Cordovez, Viviane; Guo, Yanan; Karimi Jashni, Mansoor; Bradshaw, Rosie E; de Wit, Pierre J G M

    2016-01-01

    CfAvr4, a chitin-binding effector protein produced by the Dothideomycete tomato pathogen Cladosporium fulvum, protects the cell wall of this fungus against hydrolysis by secreted host chitinases during infection. However, in the presence of the Cf-4 immune receptor of tomato, CfAvr4 triggers a hypersensitive response (HR), which renders the pathogen avirulent. Recently, several orthologues of CfAvr4 have been identified from phylogenetically closely related species of Dothideomycete fungi. Of these, DsAvr4 from Dothistroma septosporum also triggers a Cf-4-dependent HR, but CaAvr4 and CbAvr4 from Cercospora apii and Cercospora beticola, respectively, do not. All, however, bind chitin. To identify the region(s) and specific amino acid residue(s) of CfAvr4 and DsAvr4 required to trigger a Cf-4-dependent HR, chimeric and mutant proteins, in which specific protein regions or single amino acid residues, respectively, were exchanged between CfAvr4 and CaAvr4 or DsAvr4 and CbAvr4, were tested for their ability to trigger an HR in Nicotiana benthamiana plants transgenic for the Cf-4 immune receptor gene. Based on this approach, a single region common to CfAvr4 and DsAvr4 was determined to carry a conserved proline residue necessary for the elicitation of this HR. In support of this result, a Cf-4-dependent HR was triggered by mutant CaAvr4 and CbAvr4 proteins carrying an arginine-to-proline substitution at this position. This study provides the first step in deciphering how Avr4 orthologues from different Dothideomycete fungi trigger a Cf-4-dependent HR.

  3. Evaluation of Pentafluoroethane and 1,1-Difluoroethane for a Dielectric Etch Application in an Inductively Coupled Plasma Etch Tool

    NASA Astrophysics Data System (ADS)

    Karecki, Simon; Chatterjee, Ritwik; Pruette, Laura; Reif, Rafael; Sparks, Terry; Beu, Laurie; Vartanian, Victor

    2000-07-01

    In this work, a combination of two hydrofluorocarbon compounds, pentafluoroethane (FC-125, C2HF5) and 1,1-difluoroethane (FC-152a, CF2H-CH3), was evaluated as a potential replacement for perfluorocompounds in dielectric etch applications. A high aspect ratio oxide via etch was used as the test vehicle for this study, which was conducted in a commercial inductively coupled high density plasma etch tool. Both process and emissions data were collected and compared to those provided by a process utilizing a standard perfluorinated etch chemistry (C2F6). Global warming (CF4, C2F6, CHF3) and hygroscopic gas (HF, SiF4) emissions were characterized using Fourier transform infrared (FTIR) spectroscopy. FC-125/FC-152a was found to produce significant reductions in global warming emissions, on the order of 68 to 76% relative to the reference process. Although etch stopping, caused by a high degree of polymer deposition inside the etched features, was observed, process data otherwise appeared promising for an initial study, with good resist selectivity and etch rates being achieved.

  4. Atmospheric trends and radiative forcings of CF4 and C2F6 inferred from firn air.

    PubMed

    Worton, David R; Sturges, William T; Gohar, Laila K; Shine, Keith P; Martinerie, Patricia; Oram, David E; Humphrey, Stephen P; Begley, Paul; Gunn, Lara; Barnola, Jean-Marc; Schwander, Jakob; Mulvaney, Robert

    2007-04-01

    The atmospheric histories of two potent greenhouse gases, tetrafluoromethane (CF4) and hexafluoroethane (C2F6), have been reconstructed for the 20th century based on firn air measurements from both hemispheres. The reconstructed atmospheric trends show that the mixing ratios of both CF4 and C2F6 have increased during the 20th century by factors of approximately 2 and approximately 10, respectively. Initially, the increasing mixing ratios coincided with the rise in primary aluminum production. However, a slower atmospheric growth rate for CF4 appears to be evident during the 1990s, which supports recent aluminum industry reports of reduced CF4 emissions. This work illustrates the changing relationship between CF4 and C2F6 that is likely to be largely the result of both reduced emissions from the aluminum industry and faster growing emissions of C2F6 from the semiconductor industry. Measurements of C2F6 in the older firn air indicate a natural background mixing ratio of <0.3 parts per trillion (ppt), demonstrating that natural sources of this gas are negligible. However, CF4 was deduced to have a preindustrial mixing ratio of 34 -1 ppt (-50% of contemporary levels). This is in good agreement with the previous work of Harnisch et al. (18) and provides independent confirmation of their results. As a result of the large global warming potentials of CF4 and C2F6, these results have important implications for radiative forcing calculations. The radiative forcings of CF4 and C2F6 are shown to have increased over the past 50 years to values in 2001 of 4.1 x 10(-3) Wm(-2) and 7.5 x 10(-4) Wm(-2), respectively, relative to preindustrial concentrations. These forcings are small compared to present day forcings due to the major greenhouse gases but, if the current trends continue, they will continue to increase since both gases have essentially infinite lifetimes. There is, therefore, a large incentive to reduce perfluorocarbon emissions such that through the implementation of

  5. Plasma etching of dielectric materials using inductively and capacitively coupled fluorocarbon discharges: Mechanistic studies of the surface chemistry

    NASA Astrophysics Data System (ADS)

    Ling, Li

    Fluorocarbon (FC) plasmas are commonly used for dielectric materials etching. Our initial work was performed using an inductively coupled plasma (ICP) system to produce FC discharges. We first examined the effect of CO addition to C4F8 or C4F8/Ar plasmas for selective etching of organosilicate glass (OSG), which is a typical low k (LK) material over etch stop layers. The chemical activity of CO when added to either C4F8 Or C4F8/80% Ar can be understood in terms of the CO dissociation energy threshold relative to energies of inelastic electron collision processes of the dominant feedgas component. We also studied the plasma etching behavior of 193 nm and 248 nm photoresist in FC discharges used for dielectric etching. We showed that ion-enhanced selective volatilization of carbonyl groups of the 193 nm photoresist polymer backbone which is absent for the 248 nm material, along with modulation of the ion-interaction with the photoresist material by fluorocarbon surface passivation, may be responsible for the introduction of pronounced surface roughness of 193 nm photoresists. Current industrial efforts are aimed primarily at capacitively coupled plasma (CCP) systems. A home-built dual frequency CCP reactor was used to investigate additional aspects of dielectric materials plasma etching. We designed a gap structure to simulate sidewall surface processes occurring during high aspect ratio trench etching. In particular, we showed that the FC film deposition rates measured using the gap structure qualitatively correlate with the trench sidewall angles produced in LK dielectrics in both C 4F8/Ar and CF4/H2 based gas chemistries: The lower the FC deposition rate on the sidewall, the more vertical the trench sidewall. This approach was used to study surface chemistry aspects of FC film deposition with and without ion bombardment. For the gap structure film deposition takes place without ion bombardment and we observed a novel FC film growth phenomenon in pure C4F8 plasmas

  6. Dynamics of a pulsed inductively coupled oxygen plasma

    NASA Astrophysics Data System (ADS)

    Zaka-ul-Islam, Mujahid

    2016-11-01

    Inductively coupled plasma system (ICPs) is extensively used for a wide range of nanofabrication applications. The ICPs operated in a pulsed or power modulated mode has shown several advantages compared to the continuous discharge. In this work, the plasma dynamics in a planar coil pulsed inductively coupled plasma system (ICPs) operated in oxygen has been investigated, using phase and space resolved optical emission spectroscopy. It is well-known that the ICPs operates in two distinct operational modes as a function of power known as E and H modes, generated dominantly by capacitive and inductive couplings, respectively. The measurements show that the discharge ignites due a capacitive coupling (in the E-mode) and later transits to the H-mode as a function of time. The inductive coupling, however, starts during the E-mode along with capacitive coupling. The relative contribution of inductive coupling increases until the discharge reaches the E-H transition where the growth rate of inductive coupling becomes much faster. It is found that the time to reach E-H transition decreases with the pressure. At the E-H transition, the total emission has a spike-like feature (i.e., it first achieves a peak emission which later decreases and finally settles to a lower value). The 2D images of the discharge show that at the time of peak total-emission, the discharge structure is sharp and bright, which later decreases in brightness and becomes diffusive.

  7. A Coupled Plasma and Sheath Model for High Density Reactors

    NASA Technical Reports Server (NTRS)

    Deepak, Bose; Govindan, T. R.; Meyyappan, M.; Arnold, Jim (Technical Monitor)

    2001-01-01

    We present a coupled plasma and collisionless; sheath model for the simulation of high density plasma processing reactors. Due to inefficiencies in numerical schemes and the resulting computational burden, a coupled multidimensional plasma and sheath simulation has not been possible model for gas mixtures and high density reactors of practical interest. In this work we demonstrate that with a fully implicit algorithm and a refined computational mesh, a self-consistent plasma and sheath simulation is feasible. We discuss the details of the model equations, the importance of ion inertia, and the resulting sheath profiles for argon and chlorine plasmas. We find that at low operating pressures (10-30 mTorr), the charge separation occurs only within a 0.5 mm layer near the surface in a 300 mm inductively coupled plasma etch reactor. A unified model eliminates the use of off-line or loosely coupled sheath models with simplifying assumptions which generally lead to uncertainties in ion flux and sheath electrical properties.

  8. Vibrationally resolved C 1s photoionization cross section of CF4

    NASA Astrophysics Data System (ADS)

    Patanen, M.; Kooser, K.; Argenti, L.; Ayuso, D.; Kimura, M.; Mondal, S.; Plésiat, E.; Palacios, A.; Sakai, K.; Travnikova, O.; Decleva, P.; Kukk, E.; Miron, C.; Ueda, K.; Martín, F.

    2014-06-01

    The differential photoionization cross section ratio (ν = 1)/(ν = 0) for the symmetric stretching mode in the C 1s photoionization of CF4 was studied both theoretically and experimentally. We observed this ratio to differ from the Franck-Condon ratio and to be strongly dependent on the photon energy, even far from the photoionization threshold. The density-functional theory computations show that the ratio is significantly modulated by the diffraction of the photoelectrons by the neighbouring atoms at high photon energies. At lower energies, the interpretation of the first very strong maximum observed about 60 eV above the photoionization threshold required detailed calculations of the absolute partial cross sections, which revealed that the absolute cross section has two maxima at lower energies, which turn into one maximum in the cross section ratio because the maxima appear at slightly different energies in ν = 1 and ν = 0 cross sections. These two strong, low-energy continuum resonances originate from the trapping of the continuum wavefunction in the molecular potential of the surrounding fluorine atoms and from the outgoing electron scattering by them.

  9. Experimental investigation on no-vent fill process using tetrafluoromethane (CF4)

    NASA Astrophysics Data System (ADS)

    Kim, Youngcheol; Lee, Cheonkyu; Park, Jiho; Seo, Mansu; Jeong, Sangkwon

    2016-03-01

    This paper investigates the transfer of liquid cryogens using a no-vent fill (NVF) process experimentally to identify the dominant NVF parameters. The experimental apparatus has been fabricated with extensive instrumentations to precisely study the effects of each NVF parameter. Liquid tetrafluoromethane (CF4) is selected as the working fluid due to its similar molecular structures and similar normal boiling point and triple point with liquid methane which has been considered as an attractive future cryogenic propellant. The experimental results show that the initial receiver tank wall temperature and the incoming liquid temperature are the primary factors that characterize the (non-equilibrium) thermodynamic state at the start of a NVF transfer. The supply pressure is also critical as it indicates the ability to condense vapor in the receiver tank. A non-dimensional map based on energy balance is proposed to find acceptable initial conditions of the filling volume at the desired final tank pressure. The non-dimensional map shows good agreement with the NVF data not only in this paper but also in the previous research.

  10. On coupling fluid plasma and kinetic neutral physics models

    DOE PAGES

    Joseph, I.; Rensink, M. E.; Stotler, D. P.; ...

    2017-03-01

    The coupled fluid plasma and kinetic neutral physics equations are analyzed through theory and simulation of benchmark cases. It is shown that coupling methods that do not treat the coupling rates implicitly are restricted to short time steps for stability. Fast charge exchange, ionization and recombination coupling rates exist, even after constraining the solution by requiring that the neutrals are at equilibrium. For explicit coupling, the present implementation of Monte Carlo correlated sampling techniques does not allow for complete convergence in slab geometry. For the benchmark case, residuals decay with particle number and increase with grid size, indicating that theymore » scale in a manner that is similar to the theoretical prediction for nonlinear bias error. Progress is reported on implementation of a fully implicit Jacobian-free Newton–Krylov coupling scheme. The present block Jacobi preconditioning method is still sensitive to time step and methods that better precondition the coupled system are under investigation.« less

  11. Linear coupling of acoustic and cyclotron waves in plasma flows

    SciTech Connect

    Rogava, Andria; Gogoberidze, Grigol

    2005-05-15

    It is found that in magnetized electrostatic plasma flows the velocity shear couples ion-acoustic waves with ion-cyclotron waves and leads, under favorable conditions, to their efficient reciprocal transformations. It is shown that in a two-dimensional setup this coupling has a remarkable feature: it is governed by equations that are mathematically equal to the ones describing coupling of sound waves with internal gravity waves [Rogava and Mahajan, Phys. Rev. E 55, 1185 (1997)] in neutral fluids. For flows with low shearing rates a fully analytic, quantitative description of the coupling efficiency, based on a noteworthy quantum-mechanical analogy, is given and transformation coefficients are calculated.

  12. Pulse-biased etching of Si3N4-layer in capacitively-coupled plasmas for nano-scale patterning of multi-level resist structures.

    PubMed

    Lee, Hyelim; Kim, Sechan; Choi, Gyuhyun; Lee, Nae-Eung

    2014-12-01

    Pulse-biased plasma etching of various dielectric layers is investigated for patterning nano-scale, multi-level resist (MLR) structures composed of multiple layers via dual-frequency, capacitively-coupled plasmas (CCPs). We compare the effects of pulse and continuous-wave (CW) biasing on the etch characteristics of a Si3N4 layer in CF4/CH2F2/O2/Aretch chemistries using a dual-frequency, superimposed CCP system. Pulse-biasing conditions using a low-frequency power source of 2 MHz were varied by controlling duty ratio, period time, power, and the gas flow ratio in the plasmas generated by the 27.12 MHz high-frequency power source. Application of pulse-biased plasma etching significantly affected the surface chemistry of the etched Si3N4 surfaces, and thus modified the etching characteristics of the Si3N4 layer. Pulse-biased etching was successfully applied to patterning of the nano-scale line and space pattern of Si3N4 in the MLR structure of KrF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer/Si3N4. Pulse-biased etching is useful for tuning the patterning of nano-scale dielectric hard-mask layers in MLR structures.

  13. Coupled multigroup cross sections for hydrogen interactions in plasmas

    NASA Astrophysics Data System (ADS)

    Wienke, B. R.; Morel, J. E.; Cayton, T. E.; Howell, R. B.

    1985-10-01

    Using analytical fits to the experimental cross sections for H 3 H 2, and H 2+ interactions in plasmas, developed by Gryzinski, Riviere, Jones, and Freeman, we obtain coupled multigroup cross sections and rate coefficients for hydrogen transport applications. Multigroup cross sections and rate coefficients, for specified energy group boundaries, plasma particle and temperature profiles, and cylindrical plasma confinement radius, are generated against a spatially dependent, local Maxwellian scattering background. Cross sections are formatted for direct use in production multigroup S n, Monte Carlo, or specific transport applications. Ten coupled hydrogen reactions are included and resulting cross sections for ionization, scattering, and production can be coupled or decoupled. Reactions treated include H, H 2 ionization by electrons and protons, H, H 2 charge exchange, and H 2, H 2+ dissociative mechanisms. We detail the formalism used to compute effective cross sections and rates and give practicle results for two fusion reactors.

  14. Effect of strongly coupled plasma on photoionization cross section

    SciTech Connect

    Das, Madhusmita

    2014-01-15

    The effect of strongly coupled plasma on the ground state photoionization cross section is studied. In the non relativistic dipole approximation, cross section is evaluated from bound-free transition matrix element. The bound and free state wave functions are obtained by solving the radial Schrodinger equation with appropriate plasma potential. We have used ion sphere potential (ISP) to incorporate the plasma effects in atomic structure calculation. This potential includes the effect of static plasma screening on nuclear charge as well as the effect of confinement due to the neighbouring ions. With ISP, the radial equation is solved using Shooting method approach for hydrogen like ions (Li{sup +2}, C{sup +5}, Al{sup +12}) and lithium like ions (C{sup +3}, O{sup +5}). The effect of strong screening and confinement is manifested as confinement resonances near the ionization threshold for both kinds of ions. The confinement resonances are very much dependent on the edge of the confining potential and die out as the plasma density is increased. Plasma effect also results in appearance of Cooper minimum in lithium like ions, which was not present in case of free lithium like ions. With increasing density the position of Cooper minimum shifts towards higher photoelectron energy. The same behaviour is also true for weakly coupled plasma where plasma effect is modelled by Debye-Huckel potential.

  15. Modeling of Feature Profile Evolution in SiO2 as functions of Radial Position and Bias Voltage under Competition among Charging, Deposition, and Etching in Two-Frequency Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Shimada, Takashi; Yagisawa, Takashi; Makabe, Toshiaki

    2006-11-01

    A feature profile evolution model of a trench in SiO2 is developed in a two-frequency capacitively coupled plasma in CF4(5%)/Ar by considering two layers, a mixing layer and an overlaying polymer layer on the basis of a database of etching yield by extending our original physical computer-aided design (CAD) tool, VicAddress (vertically integrated computer-aided design for device processes). That is, the surface exposed to fluorocarbon plasma is considered under competition among the charging of electrons and ions, the deposition of radicals, and reactive etching by ions. The feature profile is also discussed in terms of the bias amplitude and the position on the wafer.

  16. Ion sampling and transport in Inductively Coupled Plasma Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Farnsworth, Paul B.; Spencer, Ross L.

    2017-08-01

    Quantitative accuracy and high sensitivity in inductively coupled plasma mass spectrometry (ICP-MS) depend on consistent and efficient extraction and transport of analyte ions from an inductively coupled plasma to a mass analyzer, where they are sorted and detected. In this review we examine the fundamental physical processes that control ion sampling and transport in ICP-MS and compare the results of theory and computerized models with experimental efforts to characterize the flow of ions through plasma mass spectrometers' vacuum interfaces. We trace the flow of ions from their generation in the plasma, into the sampling cone, through the supersonic expansion in the first vacuum stage, through the skimmer, and into the ion optics that deliver the ions to the mass analyzer. At each stage we consider idealized behavior and departures from ideal behavior that affect the performance of ICP-MS as an analytical tool.

  17. Plasma etching of cesium iodide

    NASA Astrophysics Data System (ADS)

    Yang, X.; Hopwood, J.; Tipnis, S.; Nagarkar, V.; Gaysinskiy, V.

    2002-01-01

    Thick films of cesium iodide (CsI) are often used to convert x-ray images into visible light. Spreading of the visible light within CsI, however, reduces the resolution of the resulting image. Anisotropic etching of the CsI film into an array of micropixels can improve the image resolution by confining light within each pixel. The etching process uses a high-density inductively coupled plasma to pattern CsI samples held by a heated, rf-biased chuck. Fluorine-containing gases such as CF4 are found to enhance the etch rate by an order of magnitude compared to Ar+ sputtering alone. Without inert-gas ion bombardment, however, the CF4 etch becomes self-limited within a few microns of depth due to the blanket deposition of a passivation layer. Using CF4+Ar continuously removes this layer from the lateral surfaces, but the formation of a thick passivation layer on the unbombarded sidewalls of etched features is observed by scanning electron microscopy. At a substrate temperature of 220 °C, the minimum ion-bombardment energy for etching is Ei~50 eV, and the rate depends on Ei1/2 above 65 eV. In dilute mixtures of CF4 and Ar, the etch rate is proportional to the gas-phase density of atomic fluorine. Above 50% CF4, however, the rate decreases, indicating the onset of net surface polymer deposition. These observations suggest that anisotropy is obtained through the ion-enhanced inhibitor etching mechanism. Etching exhibits an Arrhenius-type behavior in which the etch rate increases from ~40 nm/min at 40 °C to 380 nm/min at 330 °C. The temperature dependence corresponds to an activation energy of 0.13+/-0.01 eV. This activation energy is consistent with the electronic sputtering mechanism for alkali halides.

  18. Dust trajectories and diagnostic applications beyond strongly coupled dusty plasmas

    SciTech Connect

    Wang Zhehui; Ticos, Catalin M.; Wurden, Glen A.

    2007-10-15

    Plasma interaction with dust is of growing interest for a number of reasons. On the one hand, dusty plasma research has become one of the most vibrant branches of plasma science. On the other hand, substantially less is known about dust dynamics outside the laboratory strongly coupled dusty-plasma regime, which typically corresponds to 10{sup 15} m{sup -3} electron density with ions at room temperature. Dust dynamics is also important to magnetic fusion because of concerns about safety and potential dust contamination of the fusion core. Dust trajectories are measured under two plasma conditions, both of which have larger densities and hotter ions than in typical dusty plasmas. Plasma-flow drag force, dominating over other forces in flowing plasmas, can explain the dust motion. In addition, quantitative understanding of dust trajectories is the basis for diagnostic applications using dust. Observation of hypervelocity dust in laboratory enables dust as diagnostic tool (hypervelocity dust injection) in magnetic fusion. In colder plasmas ({approx}10 eV or less), dust with known physical and chemical properties can be used as microparticle tracers to measure both the magnitude and directions of flows in plasmas with good spatial resolution as the microparticle tracer velocimetry.

  19. Frequency coupling in dual frequency capacitively coupled radio-frequency plasmas

    SciTech Connect

    Gans, T.; Schulze, J.; O'Connell, D.; Czarnetzki, U.; Faulkner, R.; Ellingboe, A. R.; Turner, M. M.

    2006-12-25

    An industrial, confined, dual frequency, capacitively coupled, radio-frequency plasma etch reactor (Exelan registered , Lam Research) has been modified for spatially resolved optical measurements. Space and phase resolved optical emission spectroscopy yields insight into the dynamics of the discharge. A strong coupling of the two frequencies is observed in the emission profiles. Consequently, the ionization dynamics, probed through excitation, is determined by both frequencies. The control of plasma density by the high frequency is, therefore, also influenced by the low frequency. Hence, separate control of plasma density and ion energy is rather complex.

  20. Collisional three-body recombination in strongly coupled ultracold plasmas

    NASA Astrophysics Data System (ADS)

    Vorob'ev, V. S.

    2017-07-01

    The collisional three-body (e - e - ion) recombination in an ultracold plasma is considered when the temperature T is small and the coupling parameter characterizing the interaction of electrons and ions exceeds unity. For these conditions, we calculate the average energy of the electron and find the recombination coefficient. The latter for small values of the coupling parameter becomes ˜ T-9 /2 and for large ones is inversely proportional to the plasma frequency. We compare the results obtained with different theoretical models and the numerical simulation data of the recombination process.

  1. Coupled Dust-Lattice Modes in Magnetized Complex Plasmas

    SciTech Connect

    Farokhi, B.; Shahmansouri, M.

    2008-09-07

    Dust lattice wave modes in a one dimensional plasma crystal (formed by paramagnetic dust particles) suspended in the plasma sheath are studied. The ion flow in the sheath introduces 'ion wakes' below the crystal particles. The wave dispersion relations are found under the influence of inhomogeneous magnetic field, wake charge effect and equilibrium charge gradient. The expression for the wave dispersion relations clearly show that three branches exist as a result of the coupling of longitudinal and transverse modes due to the Lorenz forces, charge gradient and wake charge effect. We observe a new coupling between the dust lattice modes, which have not reported so far.

  2. Helium-like magnesium embedded in strongly coupled plasma

    SciTech Connect

    Bhattacharyya, Sukhamoy

    2016-05-06

    In recent days, with the advent of the x-ray free electron laser (FEL) with Linac coherent light source (LCLS) and the Orion laser, experimental studies on atomic systems within strongly coupled plasma environment with remarkable improvement in accuracy as compared to earlier experiments have become possible. In these kinds of experiments, hydrogen-like and helium-like spectral lines are used for determination of plasma parameters such as temperature, density. Accurate theoretical calculations are, therefore, necessary for such kind of studies within a dense plasma environment. In this work, ab initio calculations are carried out in the framework of the Rayleigh-Ritz variation principle to estimate the ground state energy of helium-like magnesium within strongly coupled plasma environment. Explicitly correlated wave functions in Hylleraas coordinates have been used to incorporate the effect of electron correlation. The ion-sphere model potential that confines the central positive ion in a finite domain filled with plasma electrons has been adopted to mimic the strongly coupled plasma environment. Thermodynamic pressure ’felt’ by the ion in the ground states due to the confinement inside the ion spheres is also estimated.

  3. Effect of bias application to plasma density in weakly magnetized inductively coupled plasma

    SciTech Connect

    Kim, Hyuk; Lee, Woohyun; Park, Wanjae; Whang, Ki-Woong

    2013-07-15

    Independent control of the ion flux and energy can be achieved in a dual frequency inductively coupled plasma (ICP) system. Typically, the plasma density is controlled by the high-frequency antenna radio-frequency (RF) power and the ion energy is controlled by the low-frequency bias RF power. Increasing the bias power has been known to cause a decrease in the plasma density in capacitively coupled discharge systems as well as in ICP systems. However, an applied axial magnetic field was found to sustain or increase the plasma density as bias power is increased. Measurements show higher electron temperatures but lower plasma densities are obtained in ordinary ICP systems than in magnetized ICP systems under the same neutral gas pressure and RF power levels. Explanations for the difference in the behavior of plasma density with increasing bias power are given in terms of the difference in the heating mechanism in ordinary unmagnetized and magnetized ICP systems.

  4. Suppression of Rayleigh Taylor instability in strongly coupled plasmas

    SciTech Connect

    Das, Amita; Kaw, Predhiman

    2014-06-15

    The Rayleigh Taylor instability in a strongly coupled plasma medium has been investigated using the equations of generalized hydrodynamics. It is demonstrated that the visco-elasticity of the strongly coupled medium due to strong inter particle correlations leads to a suppression of the Rayleigh Taylor instability unless certain threshold conditions are met. The relevance of these results to experiments on laser compression of matter to high densities including those related to inertial confinement fusion using lasers has also been shown.

  5. Nonlinear Generalized Hydrodynamic Wave Equations in Strongly Coupled Dusty Plasmas

    SciTech Connect

    Veeresha, B. M.; Sen, A.; Kaw, P. K.

    2008-09-07

    A set of nonlinear equations for the study of low frequency waves in a strongly coupled dusty plasma medium is derived using the phenomenological generalized hydrodynamic (GH) model and is used to study the modulational stability of dust acoustic waves to parallel perturbations. Dust compressibility contributions arising from strong Coulomb coupling effects are found to introduce significant modifications in the threshold and range of the instability domain.

  6. Strong Coupling Effects on Bound States in Plasmas.

    DTIC Science & Technology

    1982-08-01

    of the degree of ionization of a dense plasma (3) Generalizat on of the Thomas-Fermi-De-bye- Huckel scheme for strongly coupled plasmas with atoms and...atom is described through the replacement of the intra-atomic potential by a screened Debye potential where the screening constant K - (4re2no)1/ 2...plasma schemes-either the STLS6 or TI mean field theories , or INC. 6. Finally X is to be determined by calculating the free energy of the system and

  7. Inductively coupled plasma torch with laminar flow cooling

    DOEpatents

    Rayson, Gary D.; Shen, Yang

    1991-04-30

    An improved inductively coupled gas plasma torch. The torch includes inner and outer quartz sleeves and tubular insert snugly fitted between the sleeves. The insert includes outwardly opening longitudinal channels. Gas flowing through the channels of the insert emerges in a laminar flow along the inside surface of the outer sleeve, in the zone of plasma heating. The laminar flow cools the outer sleeve and enables the torch to operate at lower electrical power and gas consumption levels additionally, the laminar flow reduces noise levels in spectroscopic measurements of the gaseous plasma.

  8. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, D.E.; Bieniewski, T.M.

    1987-04-13

    A method of processing materials. The invention enables ultrafine, ultrapure powders to be formed from solid ingots in a gas free environment. A plasma is formed directly from an ingot which insures purity. The vaporized material is expanded through a nozzle and the resultant powder settles on a cold surface. An inductively coupled plasma may also be used to process waste chemicals. Noxious chemicals are directed through a series of plasma tubes, breaking molecular bonds and resulting in relatively harmless atomic constituents. 3 figs.

  9. Collisional coupling in counterstreaming laser-produced plasmas

    NASA Technical Reports Server (NTRS)

    Koopman, D. W.; Goforth, R. R.

    1974-01-01

    The collisional processes which transfer momentum between counterstreaming plasmas are reviewed and applied to the example of a laser-produced plasma expanding into a partially ionized background. Experimental measurements of the dependence of the ion flow field on collisional momentum transfer demonstrate the validity of the simplified treatment of collision processes which have been adopted. A numerical model which simulates the laser-plasma interaction with the background confirms the importance of collisions in previous experimental studies of momentum coupling, and provides some insight into the distinction between collisional and collisionless flow regimes.

  10. Efficient destruction of CF4 through in situ generation of alkali metals from heated alkali halide reducing mixtures.

    PubMed

    Lee, Myung Churl; Choi, Wonyong

    2002-03-15

    Perfluorocarbons (PFCs) are the most potent green house gases that are very recalcitrant at destruction. An effective way of converting PFCs using hot solid reagents into safe products has been recently introduced. By investigating the thermal reductive destruction of tetrafluoromethane (CF4) we provided new insight and more physicochemical consideration on this novel process. The complete destruction of CF4was successfully achieved by flowing the gas through a heated reagent bed (400-950 degrees C) that contained powder mixtures of alkali halides, CaO, and Si. The silicon acted as a reducing agent of alkali halides for the in-situ production of alkali metals, and the calcium oxide played the role of a halide ion acceptor. The absence of any single component in this ternary mixture drastically reduced the destruction efficiency of CF4. The CF4 destruction efficiencies with the solid reagent containing the alkali halide, MX, increased in the order of Li approximately Na < K < Cs for alkali cations and I < Br < Cl < F for halide anions. This trend agreed with the endothermicity of the alkali metal generation reaction: the higher the endothermicity, the lower the destruction efficiency. Alkali metal generation was indirectly detected by monitoring H2 production from its reaction with water. The production of alkali metals increased with NaF, KF, and CsF in this order. The CsF/CaO/Si system exhibited the complete destruction of CF4 at as low as 600 degrees C. The solid product analysis by X-ray diffraction (XRD) showed the formation of CaF2 and the depletion of Si with black carbon particles formed in the solid reagent residue. No CO/CO2 and toxic HF and SiF4 formation were detected in the exhaust gas.

  11. Emissions of Tetrafluoromethane (CF4) and Hexafluoroethane (C2F6) from East Asian Aluminum and Semiconductor Industries

    NASA Astrophysics Data System (ADS)

    Kim, J.; Li, S.; Muhle, J.; Fang, X.; Manning, A. J.; Arnold, T.; Park, S.; Park, M.; Saito, T.; Yokouchi, Y.; Stohl, A.; Weiss, R. F.; Kim, K.

    2013-12-01

    Tetrafluoromethane (CF4) and Hexafluoroethane (C2F6) are among the most potent greenhouse gases (GHGs), with atmospheric lifetimes of 50,000 and 10,000 years and 100-year Global Warming Potentials of 7,490 and 12,200, respectively. The Chinese aluminum smelting (AL) industry, accounting for 39% of the global aluminum production in 2010, has become a significant emitter of these compounds to the atmosphere, . The AL industry has estimated its Chinese emissions averaged over 2008-2010 at 1.4 Gg/yr of CF4 and 0.06 Gg/yr of C2F6. In this study we combine East Asian measurements of C2F6 at Gosan (Jeju Island, Korea), Hateruma, and Ochi-Ishi (Japan) and of CF4 at Gosan, using inversion techniques and two Lagrangian particle dispersion models (FLEXPART and NAME), to estimate the emissions of these two compounds from China and East Asia. Our results yield total emissions from China for the 2008-2010 period of approximately 4 × 0.5 Gg/yr for CF4 and 0.8 × 0.1 Gg/yr for C2F6. These results may be reconciled if emissions of these compounds from China's semiconductor (SC) industry are larger than currently estimated. However, evidence presented in the analysis of the inversion results and in the C2F6/CF4 emission ratios observed for China suggest that China's AL industry emissions are likely to be the dominant source of the discrepancy between reported emissions and those inferred from atmospheric measurements. As the AL and SC industries evolve toward new manufacturing technologies that reduce GHG emissions, continued and improved atmospheric measurements and modeling in this region will be useful in assessing the effectiveness of these changes.

  12. Electron-impact total ionization cross sections of CF4, C2F6, and C3F8

    NASA Astrophysics Data System (ADS)

    Nishimura, H.; Huo, Winifred M.; Ali, M. A.; Kim, Yong-Ki

    1999-02-01

    Both theoretical and experimental electron-impact total ionization cross sections of CF4, C2F6, and C3F8 are presented. The experimental cross sections have been measured as a function of incident electron energy T from threshold to 3 keV. A parallel plate condenser type apparatus was used. The molecular polarizability for C3F8 was empirically estimated to be α=10.6 Å3±0.8 Å3. Theoretical cross sections calculated from the binary-encounter-Bethe (BEB) method, which combines a modified form of the Mott cross section and the Bethe cross section, are compared with the experimental cross sections. The BEB cross sections calculated from correlated molecular wave functions with theoretical estimates for multiple ionization are about 10% higher than the experimental data at the peak for CF4, while they are in excellent agreement with the experimental data for C2F6 and C3F8. Our analysis shows that the BEB theory implicitly includes part of neutral dissociation, such as CF4→CF3+F, and hence tends to be an upper limit to the total ionization cross section. We found that the difference between our best theory for CF4 and the present experimental cross section exhibits a remarkable similarity to the shape of the recently measured cross section for neutral dissociation, though there is no a priori reason for the similarity. Owing to the large number of bound electrons, the correlation included in our wave functions for C2F6 and C3F8 is more limited than for CF4. Hence, we believe that for these two molecules the calculated cross sections are lower than the true BEB values, in spite of the apparent excellent agreement between the theory and the experiment.

  13. Langmuir probe differential measurement technique in inductively coupled RF plasmas

    NASA Astrophysics Data System (ADS)

    Djermanov, I.; Djermanova, N.; Kiss'ovski, Zh; Tsankov, Ts

    2007-04-01

    A differential measurement technique has been proposed in order to reduce noise level and stray capacitance leakage usually affecting Langmuir probe data. The technique employs two identically designed and biased Langmuir probes, connected to an instrumentation amplifier. Both probes are immersed in plasma of approximately the same space potential, one of them being plasma current collecting probe, and the second one being isolated from plasma and serving as a pick-up probe, detecting leakage currents from parasitic capacitive coupling and noise. Avoiding averaging of probe current data is the main advantage of the proposed differential technique. Experiments in the plasma expansion region of inductively driven RF source are shown to achieve lower electron temperature and higher electron density as measured by conventional single Langmuir probe. Obtaining more sharpness of the "knee" on the characteristic, thus lowering the uncertainty in plasma potential is another true merit of the differential Langmuir probe technique.

  14. Cross-Frequency Coupling of Plasma Waves in the Magnetosphere

    NASA Astrophysics Data System (ADS)

    Khazanov, G. V.

    2014-12-01

    Wave-particle and wave-wave interactions are crucial elements of magnetosphere and ionosphere plasma dynamics. Such interactions provide a channel of energy redistribution between different plasma populations, and lead to connections between physical processes developing on different spatial and temporal scales. The lower hybrid waves (LHWs) are particularly interesting for plasma dynamics, because they couple well with both electrons and ions. The excitation of LHWs is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven and/or EMIC waves, in particular those associated with lower frequency (LF) turbulence, may generate LHWs in the auroral zone and ring current region and in some cases this serves as the Alfven and/or EMIC waves saturation mechanism. We believe that this described scenario, as well as some other cross-frequency coupling of plasma waves processes that will be discussed in this presentation, can play a vital role in various parts of the magnetospheric plasma, especially in the places under investigation by the NASA THEMIS and Van Allen Probes (formerly known as the Radiation Belt Storm Probes (RBSP)) missions.

  15. Model for a transformer-coupled toroidal plasma source

    SciTech Connect

    Rauf, Shahid; Balakrishna, Ajit; Chen Zhigang; Collins, Ken

    2012-01-15

    A two-dimensional fluid plasma model for a transformer-coupled toroidal plasma source is described. Ferrites are used in this device to improve the electromagnetic coupling between the primary coils carrying radio frequency (rf) current and a secondary plasma loop. Appropriate components of the Maxwell equations are solved to determine the electromagnetic fields and electron power deposition in the model. The effect of gas flow on species transport is also considered. The model is applied to 1 Torr Ar/NH{sub 3} plasma in this article. Rf electric field lines form a loop in the vacuum chamber and generate a plasma ring. Due to rapid dissociation of NH{sub 3}, NH{sub x}{sup +} ions are more prevalent near the gas inlet and Ar{sup +} ions are the dominant ions farther downstream. NH{sub 3} and its by-products rapidly dissociate into small fragments as the gas flows through the plasma. With increasing source power, NH{sub 3} dissociates more readily and NH{sub x}{sup +} ions are more tightly confined near the gas inlet. Gas flow rate significantly influences the plasma characteristics. With increasing gas flow rate, NH{sub 3} dissociation occurs farther from the gas inlet in regions with higher electron density. Consequently, more NH{sub 4}{sup +} ions are produced and dissociation by-products have higher concentrations near the outlet.

  16. Hollow cathode plasma coupling study, 1986

    NASA Technical Reports Server (NTRS)

    Wilbur, Paul J.

    1986-01-01

    The electron collection and emission characteristics of a simple hollow cathode contactor, an extended anode hollow cathode contactor supplied by JSC, and a ring cusp magnetic field contactor are presented and the effects of discharge power and argon or xenon expellant flowrate on these characteristics are examined. All of the contactors are shown to exhibit good electron emission performance over a wide range of discharge power and expellant type and flowrate. Good electron performance is shown to be more difficult to achieve. Results suggest that the extended anode and ring cusp contactors should perform satisfactorily to electron emission currents beyond 1000 mA and electron collection currents beyond 500 mA. All contactors performed better on xenon than argon. A general theory of plasma contactor operation in both the electron collection and electron emission modes, which describes the current-limiting effects of space-charge phenomena is given. This current-limiting and collecting phenomenon is shown to be a function of driving potential differences and emitting and collecting surface radius ratio for the case of a spherical geometry. Discharge power did not appear to influence the electron collection current substantially in the experiments so it is suggested in light of the model that the contactors are generally not limited by their ion production capabilities under conditions at which they were tested.

  17. Chaotic dynamics of coupled transverse-longitudinal plasma oscillations in magnetized plasmas.

    PubMed

    Teychenné, D; Bésuelle, E; Oloumi, A; Salomaa, R R

    2000-12-25

    The propagation of intense electromagnetic waves in cold magnetized plasma is tackled through a relativistic hydrodynamic approach. The analysis of coupled transverse-longitudinal plasma oscillations is performed for traveling plane waves. When these waves propagate perpendicularly to a static magnetic field, the model is describable in terms of a nonlinear dynamical system with 2 degrees of freedom. A constant of motion is obtained and the powerful classical mechanics methods can be used. A new class of solutions, i.e., the chaotic solutions, is discovered by the Poincaré surface of sections. As a result, coupled transverse-longitudinal plasma oscillations become aperiodically modulated.

  18. Inductively-coupled-plasma-induced electret enhancement for triboelectric nanogenerators.

    PubMed

    Liu, Long; Tang, Wei; Wang, Zhong Lin

    2017-01-20

    Polyethylene terephthalate (PET) films' electret property was significantly enhanced after being treated with inductively coupled plasma (ICP). Based on this modified material, the triboelectric nanogenerators' (TENGs) transferred charges remained at 68.6% of the initial value after 400 000 cycles of contact-separation process, which was about three times that of the untreated samples.

  19. Inductively-coupled-plasma-induced electret enhancement for triboelectric nanogenerators

    NASA Astrophysics Data System (ADS)

    Liu, Long; Tang, Wei; Wang, Zhong Lin

    2017-01-01

    Polyethylene terephthalate (PET) films’ electret property was significantly enhanced after being treated with inductively coupled plasma (ICP). Based on this modified material, the triboelectric nanogenerators’ (TENGs) transferred charges remained at 68.6% of the initial value after 400 000 cycles of contact-separation process, which was about three times that of the untreated samples.

  20. Jeans self gravitational instability of strongly coupled quantum plasma

    SciTech Connect

    Sharma, Prerana; Chhajlani, R. K.

    2014-07-15

    The Jeans self-gravitational instability is studied for quantum plasma composed of weakly coupled degenerate electron fluid and non-degenerate strongly coupled ion fluid. The formulation for such system is done on the basis of two fluid theory. The dynamics of weakly coupled degenerate electron fluid is governed by inertialess momentum equation. The quantum forces associated with the quantum diffraction effects and the quantum statistical effects act on the degenerate electron fluid. The strong correlation effects of ion are embedded in generalized viscoelastic momentum equation including the viscoelasticity and shear viscosities of ion fluid. The general dispersion relation is obtained using the normal mode analysis technique for the two regimes of propagation, i.e., hydrodynamic and kinetic regimes. The Jeans condition of self-gravitational instability is also obtained for both regimes, in the hydrodynamic regime it is observed to be affected by the ion plasma oscillations and quantum parameter while in the kinetic regime in addition to ion plasma oscillations and quantum parameter, it is also affected by the ion velocity which is modified by the viscosity generated compressional effects. The Jeans critical wave number and corresponding critical mass are also obtained for strongly coupled quantum plasma for both regimes.

  1. Effects of antenna coil turns on plasma density and antenna voltage in solenoidal inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Moon, Jun-Hyeon; Kim, Kyung-Hyun; Lin, Ming-Chieh; Chung, Chin-Wook

    2016-11-01

    The number of antenna coil turns, N , that affects the plasma density is a significant factor to design an inductively coupled plasma source. The equivalent resistance and inductance of a transformer circuit seen at the antenna coil are known to increase with N . This can enhance the power transfer efficiency. However, there is an undesired capacitive coupling between the antenna coil and the plasma. The antenna voltage related to the capacitive coupling is known to be proportional to N . In this work, to investigate the effects of N , the plasma density and the antenna coil voltage are measured by a floating probe and high-voltage probes, respectively. A terminal capacitor is used to suppress the capacitive coupling. As a result, the effects of N are clearly observed on the plasma densities and the voltages of the antenna coil. The plasma density was found to dramatically increase with N while the capacitive coupling is suppressed. The antenna voltage was not increased with N , and it was investigated by the ratio of the antenna voltage to the total voltage.

  2. Positron scattering from hydrogen atom embedded in weakly coupled plasma

    NASA Astrophysics Data System (ADS)

    Ghoshal, Arijit; Kamali, M. Z. M.; Ratnavelu, K.

    2013-01-01

    The positron-hydrogen collision problem in weakly coupled plasma environment has been investigated by applying a formulation of the three-body collision problem in the form of coupled multi-channel two-body Lippmann-Schwinger equations. The interactions among the charged particles in the plasma have been represented by Debye-Huckel potentials. A simple variational hydrogenic wave function has been employed to calculate the partial-wave scattering amplitude. Plasma screening effects on various possible mode of fragmentation of the system e++H(1s) during the collision, such as 1s →1s and 2s→2s elastic collisions, 1s→2s excitation, positronium formation, elastic proton-positronium collisions, have been reported. Furthermore, a detailed study has been made on differential and total cross sections of the above processes in the energy range 13.6-350 eV of the incident positron.

  3. Mobility in a strongly coupled dusty plasma with gas

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Goree, J.

    2014-04-01

    The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force F, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity up. The mobility μp=up/F of the projectile's motion is obtained. Two regimes depending on F are identified. In the high-force regime, μp∝F0.23, and the scattering cross section σs diminishes as up-6/5. Results for σs are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments.

  4. Mobility in a strongly coupled dusty plasma with gas.

    PubMed

    Liu, Bin; Goree, J

    2014-04-01

    The mobility of a charged projectile in a strongly coupled dusty plasma is simulated. A net force F, opposed by a combination of collisional scattering and gas friction, causes projectiles to drift at a mobility-limited velocity up. The mobility μp=up/F of the projectile's motion is obtained. Two regimes depending on F are identified. In the high-force regime, μp∝F0.23, and the scattering cross section σs diminishes as up-6/5. Results for σs are compared with those for a weakly coupled plasma and for two-body collisions in a Yukawa potential. The simulation parameters are based on microgravity plasma experiments.

  5. Improvement of uniformity in a weakly magnetized inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, W. H.; Cheong, H. W.; Kim, J. W.; Whang, K. W.

    2015-12-01

    Magnetic fields are applied to inductively coupled plasma (ICP) to achieve high plasma densities using electromagnets. If the magnetic fields are set up such that the magnitude of magnetic flux density on the substrate decreases with both radial and axial distances from the substrate’s center (here after referred to as M-ICP-A), the plasma density increases by 237% compared with that for ICP although the non-uniformity of the plasma density for M-ICP-A (11.1%) is higher than that for ICP (10.9%). As the rate of decrease in the magnitude of magnetic flux density on the substrate increases both radially and axially, the non-uniformity in the plasma density increases further. The increase in the non-uniformity for M-ICP-A was confirmed to arise from the flute instability. To suppress the flute instability, we arranged the magnitude of magnetic flux density on the substrate to increase with increasing distance from the substrate center both radially and axially (here after referred to as M-ICP-V). In this configuration, plasma fluctuations were not observed, hence the plasma density non-uniformity was lowered to 8.1%, although the measured plasma density was higher than that for M-ICP-A. The oxide etch-rate non-uniformity in M-ICP-V (2.5%) was also lower than that for ICP (5.2%) or that for M-ICP-A (21.4%).

  6. Characterization of inductively coupled plasma generated by a quadruple antenna

    NASA Astrophysics Data System (ADS)

    Shafir, G.; Zolotukhin, D.; Godyak, V.; Shlapakovski, A.; Gleizer, S.; Slutsker, Ya; Gad, R.; Bernshtam, V.; Ralchenko, Yu; Krasik, Ya E.

    2017-02-01

    The results of the characterization of large-scale RF plasma for studying nonlinear interaction with a high-power (˜400 MW) short duration (˜0.8 ns) microwave (˜10 GHz) beam are presented. The plasma was generated inside a Pyrex tube 80 cm in length and 25 cm in diameter filled by either Ar or He gas at a pressure in the range 1.3-13 Pa using a 2 MHz RF generator with a matching system and a quadruple antenna. Good matching was obtained between the plasma parameters, which were determined using different methods including a movable Langmuir probe, microwave cut-off, interferometry, and optical emission spectroscopy. It was shown that, depending on the gas pressure and RF power delivered to the antenna, the plasma density and electron temperature can be controlled in the range 1 × 1010-5 × 1012 cm-3 and 1-3.5 eV, respectively. The plasma density was found to be uniform in terms of axial (˜60 cm) and radial (˜10 cm) dimensions. Further, it was also shown that the application of the quadruple antenna, with resonating capacitors inserted in its arms, decreases the capacitive coupling of the antenna and the plasma as well as the RF power loss along the antenna. These features make this plasma source suitable for microwave plasma wake field experiments.

  7. AETHER: A simulation platform for inductively coupled plasma

    SciTech Connect

    Turkoz, Emre Celik, Murat

    2015-04-01

    An in-house code is developed to simulate the inductively coupled plasma (ICP). The model comprises the fluid, electromagnetic and transformer submodels. Fluid equations are solved to evaluate the plasma flow parameters, including the plasma and neutral densities, ion and neutral velocities, electron flux, electron temperature, and electric potential. The model relies on the ambipolar approximation and offers the evaluation of plasma parameters without solving the sheath region. The electromagnetic model handles the calculation of the electric and magnetic fields using the magnetic vector potential. The transformer model captures the effect of the matching circuit utilized in laboratory experiments for RF power deposition. The continuity and momentum equations are solved using finite volume method. The energy, electric potential, and magnetic vector potential equations are solved using finite difference method. The resulting linear systems of equations are solved with iterative solvers including Jacobi and GMRES. The code is written using the C++ programming language, it works in parallel and has graphical user interface. The model is applied to study ICP characteristics of a plasma confined within a cylindrical chamber with dielectric walls for two different power deposition cases. The results obtained from the developed model are verified using the plasma module of COMSOL Multiphysics. The model is also applied to a plasma source configuration, and it is demonstrated that there is an overall increase in the plasma potential when current is extracted from ICP with a biased wall electrode.

  8. Copropagation of coupled laser pulses in magnetized plasmas: Modulational instability and coupled solitons

    NASA Astrophysics Data System (ADS)

    Borhanian, Jafar; Aghaei Golijan, Hassan

    2017-03-01

    The nonlinear propagation of two circularly polarized strong laser pulses in a magnetized plasma is considered. In a weakly relativistic regime, it is shown that the evolution of amplitudes of the laser pulses is governed by two coupled cubic nonlinear Schrödinger (NLS) equations. The modulational instability of coupled plane wave solutions is investigated based on coupled NLS equations. The dependence of the growth rate on relevant parameters of the system is addressed. The possibility of formation of various kinds of coupled solitary wave solutions in magnetized and unmagnetized cases is considered, and the variation of the profile of these solutions with different parameters is explored.

  9. Dust acoustic waves in strongly coupled dissipative plasmas

    NASA Astrophysics Data System (ADS)

    Xie, B. S.; Yu, M. Y.

    2000-12-01

    The theory of dust acoustic waves is revisited in the frame of the generalized viscoelastic hydrodynamic theory for highly correlated dusts. Physical processes relevant to many experiments on dusts in plasmas, such as ionization and recombination, dust-charge variation, elastic electron and ion collisions with neutral and charged dust particles, as well as relaxation due to strong dust coupling, are taken into account. These processes can be on similar time scales and are thus important for the conservation of particles and momenta in a self-consistent description of the system. It is shown that the dispersion properties of the dust acoustic waves are determined by a sensitive balance of the effects of strong dust coupling and collisional relaxation. The predictions of the present theory applicable to typical parameters in laboratory strongly coupled dusty plasmas are given and compared with the experiment results. Some possible implications and discrepanies between theory and experiment are also discussed.

  10. Three-Dimensional Electromagnetic Plasma Modeling of Inductively Coupled Plasma Source and Antenna

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Agarwal, Ankur; Kenney, Jason; Wu, Ming-Feng; Collins, Ken

    2012-10-01

    Inductively coupled plasmas (ICP) are widely used for etching and deposition in the semiconductor industry. As device dimensions shrink with concomitant decreased tolerance for variability, it is critical to improve plasma and process uniformity in all plasma processes. In ICP systems, one of the major sources of non-uniformity is the radio-frequency (RF) antenna used to generate the electromagnetic wave. Discontinuities at current feed and grounding locations as well as electromagnetic field variations along the antenna coils can perturb the azimuthal electric field, resulting in a non-uniform plasma. For plasma modeling of ICP systems, a related problem is how capacitive coupling from the antenna is accounted for. ICP models have generally considered field variation along the antenna and capacitive coupling using simplified circuit models for the antenna structures. Modern ICP antennas are however quite complicated, making circuit approximations of the antenna too crude for system design. A three-dimensional parallel plasma model is described in this paper, where the full set of Maxwell equations are solved in conjunction with plasma transport equations for the plasma and the antenna. Several examples from the use of this model in ICP system design are presented.

  11. Ignition Delay in a Pulsed Inductively Coupled Plasma (ICP) in Tandem with an Auxiliary ICP

    NASA Astrophysics Data System (ADS)

    Donnelly, Vincent M.; Liu, Lei; Sridhar, Shyam; Economou, Demetre J.

    2015-09-01

    Plasma ignition delays were observed in a ``main'' ICP, in tandem with an ``auxiliary'' ICP. The Faraday-shielded ICPs were separated by a grounded metal grid. Power (13.56 MHz) to the main ICP was pulsed with a frequency of 1 kHz, while the auxiliary ICP was operated in continuous wave (cw) mode. In chlorine plasmas, ignition delay was observed for duty cycles greater than 60% and, in contrast to expectation, the delay was longer with increasing duty cycle up to ~ 99.5%. The ignition delay could be manipulated by changing the auxiliary and/or main ICP power. Langmuir probe measurements provided the temporal evolution of electron temperature, and electron and positive ion (n+) densities. These measurements revealed that the plasma was re-ignited shortly after the decaying n+ in the main ICP reached the density (n+,aux) measured when only the auxiliary ICP was powered. At that time, the depressed electron density increased sharply resulting in plasma re-ignition. Plasma ignition delay occurred when the afterglow of the pulsed plasma was not long enough for n+ to reach n+,aux during the afterglow. Besides Cl2, plasma ignition delays were also observed in other electronegative gases (SF6, CF4/O2 and O2) but not in an electropositive gas (Ar).

  12. A Coupled Plasma-Sheath Model for High Density Sources

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2000-01-01

    High density, low pressure plasmas are used for etching and deposition in microelectronics fabrication processes. The process characteristics are strongly determined by the ion energy distribution (IED) and the ion flux arriving at the substrate that are responsible for desorption of etch products and neutral dissociation at the surface. The ion flux and energy are determined by a self- consistent modeling of the bulk plasma, where the ions and the neutral radicals are produced, and the sheath, where the ions are accelerated. Due to their widely different time scales, it is a formidable task to self-consistently resolve non-collisional sheath in a high density bulk plasma model. In this work, we first describe a coupled plasma-sheath model that attempts to resolve the non-collisional sheath in a reactor scale model. Second, we propose a semianalytical radio frequency (RF) sheath model to improve ion dynamics.

  13. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan

    1998-11-01

    The coupling parameter Γ=e^2/akT, where a is the mean ion-ion separation, expresses the ratio of the mean potential energy of ions in a plasma to their mean kinetic energy. Plasma is said to be strongly coupled when Γ is greater than unity. Transport properties of strongly coupled plasmas are of interest in the study of the structure of dense astrophysical objects and gaseous planetary interiors, as well as in arcs and laser-produced plasmas. We are attempting to measure the electrical conductivity of strongly coupled metal plasmas (copper, tungsten and aluminum) in the temperature range 8-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. They may have coupling parameters Γ ranging from as high as 100 down to unity Plasmas are created by rapid vaporization of metal wire in a glass capillary or in a water bath which act as a tamper, slowing the expansion rate. The effect of the tamper is to force the interior pressure of the plasma to be fairly uniform. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL sesame database(SESAME: The Los Alamos National Laboratory Equation of State Database, Report No. LA-UR-92-3407, Ed. S. P. Lyon and J. D. Johnson, Group T-1 (unpublished)), and a brightness temperature may be obtained from radiation measurements. The column resistance is simply determined from time-resolved voltage and current measurements. For temperatures less than about 14,000K, as density decreases from the highest values measured, the conductivity falls roughly as the cube of density, reaches a minimum, and subsequently rises to approach the Spitzer prediction at low density. The rate of change of conductivity with density becomes less rapid as temperature increases, and the minimum becomes less pronounced, disappearing altogether above

  14. Collision-less Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton Sergeivich

    The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space environments, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these and other related phenomena, collision-less electro-magnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collision-less coupling mechanisms, compliment in situ measurements, and provide validation of previous computational and theoretical work, the present research utilizes a unique experimental platform at the University of California, Los Angeles (UCLA) to study the interaction of explosive debris plasma with magnetized ambient plasma in a reproducible laboratory setting. Specifically, by jointly employing the Large Plasma Device (LAPD) and the Phoenix laser facility, the super-Alfvenic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma is investigated via a variety of sophisticated diagnostics, including emission spectroscopy, wavelength-filtered imaging, a magnetic flux probe, and a Langmuir probe. The key result is the direct observation of collision-less coupling via large Doppler shifts in a He II ion spectral line, which indicate that the ambient ions accelerate in response to the explosive debris plasma. Specifically, the He II ions accelerate along a trajectory that qualitatively corresponds to the large-scale laminar electric field generated by the debris expansion. A custom computational approach is utilized to simulate the initial He II ion response to the explosive debris plasma, and a synthetic Doppler-shifted wavelength spectrum constructed from the simulated ion velocities excellently reproduces the experimental

  15. Pair correlation functions of strongly coupled two-temperature plasma

    NASA Astrophysics Data System (ADS)

    Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.

    2017-09-01

    Using molecular dynamics simulations, we perform the first direct tests of three proposed models for the pair correlation functions of strongly coupled plasmas with species of unequal temperature. The models are all extensions of the Ornstein-Zernike/hypernetted-chain theory used to good success for equilibrium plasmas. Each theory is evaluated at several coupling strengths, temperature ratios, and mass ratios for a model plasma in which the electrons are positively charged. We show that the model proposed by Seuferling et al. [Phys. Rev. A 40, 323 (1989)] agrees well with molecular dynamics over a wide range of mass and temperature ratios, as well as over a range of coupling strength similar to that of the equilibrium hypernetted-chain (HNC) theory. The SVT model also correctly predicts the strength of interspecies correlations and exhibits physically reasonable long-wavelength limits of the static structure factors. Comparisons of the SVT model with the Yukawa one-component plasma (YOCP) model are used to show that ion-ion pair correlations are well described by the YOCP model up to Γe≈1 , beyond which it rapidly breaks down.

  16. Energy exchange in strongly coupled plasmas with electron drift

    SciTech Connect

    Akbari-Moghanjoughi, M.; Ghorbanalilu, M.

    2015-11-15

    In this paper, the generalized viscoelastic collisional quantum hydrodynamic model is employed in order to investigate the linear dielectric response of a quantum plasma in the presence of strong electron-beam plasma interactions. The generalized Chandrasekhar's relativistic degeneracy pressure together with the electron-exchange and Coulomb interaction effects are taken into account in order to extend current research to a wide range of plasma number density relevant to big planetary cores and astrophysical compact objects. The previously calculated shear viscosity and the electron-ion collision frequencies are used for strongly coupled ion fluid. The effect of the electron-beam velocity on complex linear dielectric function is found to be profound. This effect is clearly interpreted in terms of the wave-particle interactions and their energy-exchange according to the sign of the imaginary dielectric function, which is closely related to the wave attenuation coefficient in plasmas. Such kinetic effect is also shown to be in close connection with the stopping power of a charged-particle beam in a quantum plasma. The effect of many independent plasma parameters, such as the ion charge-state, electron beam-velocity, and relativistic degeneracy, is shown to be significant on the growing/damping of plasma instability or energy loss/gain of the electron-beam.

  17. Effects of driving frequency on properties of inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Godyak, Valery; Kolobov, Vladimir

    2016-10-01

    Inductively coupled plasma (ICP) can be maintained over a wide range of driving frequencies from 50 Hz up to GHz. In this paper, we analyze how the properties of ICP depend on driving frequency ω. With respect to the time of ion transport to the walls, τd and the electron energy relaxation time τɛ three operating regimes are distinguished. The quasi-static regime, ωτd << 1 , the high-frequency regime, ωτɛ >> 1 and the intermediate dynamic regime, 1 /τd < ω <1 /τɛ. In the quasi-static regime, plasma density oscillates significantly over the field period. In the high-frequency regime, the plasma density and the electron energy distribution function (EEDF) are constant. In the dynamic regime, the plasma density is constant, while the EEDF varies over the field period. Depending on ICP configuration, the induced by the coil magnetic fields inside ICP, Bc can be zero or not. For example, in ICP maintained by a long helical coil with the plasma current flowing outside the coil, Bc = 0 , while when the plasma current flows inside the coil, Bc ≠ 0 . We show that in the latter case, in the quasi-static regimes, electrons become magnetized over a significant part of the period that may strongly affect the plasma properties. Examples of ICP simulations in different frequency regimes will be demonstrated in this paper.

  18. Dynamics for the dynamic Frank Harris: Exploring H+ + CF4 at Elab = 20 and 30 eV

    NASA Astrophysics Data System (ADS)

    Maiti, Buddhadev; McLaurin, Patrick M.; Sadeghi, Raymond; Ajith Perera, S.; Morales, Jorge A.

    The H+ + CF4 reaction at collision energies ELab = 20 and 30 eV is investigated with the electron nuclear dynamics (END) theory. The level of END herein employed prescribes a classical-mechanics description for the nuclei and a single-determinantal representation for the electrons. The results include visualizations of the simulated collisions, and calculations of various scattering properties. The present simulations always predict noncharge-transfer scattering (NCTS) for H+ + CF4 and exclude charge-transfer, dissociation, and rearrangement reactions. The predicted rainbow angles and the total NCTS differential cross sections agree satisfactorily with the available experimental results. The present results are compared with those of the previously simulated H+ + CH4.

  19. Thin film coating process using an inductively coupled plasma

    DOEpatents

    Kniseley, Richard N.; Schmidt, Frederick A.; Merkle, Brian D.

    1990-01-30

    Thin coatings of normally solid materials are applied to target substrates using an inductively coupled plasma. Particles of the coating material are vaporized by plasma heating, and pass through an orifice to a first vacuum zone in which the particles are accelerated to a velocity greater than Mach 1. The shock wave generated in the first vacuum zone is intercepted by the tip of a skimmer cone that provides a second orifice. The particles pass through the second orifice into a second zone maintained at a higher vacuum and impinge on the target to form the coating. Ultrapure coatings can be formed.

  20. Relations for the thermodynamic and transport properties in the testing environment of the Langley hypersonic CF4 tunnel

    NASA Technical Reports Server (NTRS)

    Sutton, K.

    1981-01-01

    Thermodynamic and transport properties of gaseous CF4 that can be used in flow field computer codes and theoretical analyses for comparison of results with experimental data from the Langley Hypersonic CF4 Tunnel are presented. The thermodynamic relations which are based on thermally perfect but calorifically imperfect gas are adequate for the testing environment of the CF4 tunnel and are simpler to use than the imperfect gas relations required to define the complete expansion from the tunnel reservoir. Relations for the transport properties are based on the kinetic theory of gases in which published experimental data are used in the derivation of the relations. Extensive experimental data were located for viscosity and the derived relation should provide values for viscosity with errors of less than 1 percent. The experimental data for thermal conductivity were limited with significant disagreement between the various sources. The derived relation will probably provide values for the thermal conductivity with errors of no more than 5 percent which is within the accuracy of the experimental data.

  1. Use of a pulse-periodic optically pumped CF4 laser for photofragmentation of UF6 molecules

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Yurij A.; Kotov, A. A.; Novikov, Victor P.

    1998-05-01

    Investigations of fragmentation of uranium hexafluoride molecules in radiation field of the optically pumped CF4 laser are carried out. The optical pumping was made by the pulse-periodic TEA CO2 laser. The optical cell of the CF4 laser was cooled by nitrogen vapor with automatic stabilization of the temperature. The maximum radiation energy carried by a single CF4 laser pulse is 250 mJ and the average power at a pulse repetition frequency of 50 Hz is up to 6 W. It was found that besides the direct fragmentation of UF6 molecules, the bimolecular V-V exchange realizes most probably at collision of highly excited molecules, consequently the vibronic energy of one of the molecules can exceed the dissociation threshold. Increase by an order of the UF6 molecules photofragmentation efficiency at presence of hydrogen can be explained by high chemical activation because of reverse electron relaxation of highly vibronic excited UF6 molecules. There is also ascertained that polymerization of UF5 radicals appears to be the most high-speed of al secondary reactions. In the main part the polymers ar found on the cell surface having number of the radicals in range from 2 to approximately 10.

  2. Decomposition of Potent Greenhouse Gases SF6, CF4 and SF5CF3 by Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Renxi; Wang, Jingting; Cao, Xu; Hou, Huiqi

    2016-04-01

    For their distinguished global warming potential (GWP100) and long atmosphere lifespan, CF4, SF6 and SF5CF3 were significant in the field of greenhouse gas research. The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge (DBD) reactor to decompose these potent greenhouse gases in this work. The results showed that SF6 could be decomposed by 92% under the conditions of 5 min resident time and 3000 V applied voltage with the partial pressure of 2.0 kPa, 28.2 kPa, and 1.8 kPa for SF6, air and water vapor, respectively. 0.4 kPa CF4 could be decomposed by 98.2% for 4 min resident time with 30 kPa Ar added. The decomposition of SF5CF3 was much more effective than that of SF6 and CF4 and moreover, 1.3 kPa SF5CF3, discharged with 30 kPa O2, Ar and air, could not be detected when the resident time was 80 s, 40 s, and 120 s, respectively. All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases. supported by National Natural Science Foundation of China (Nos. 20507004, 21577023)

  3. Laboratory study of collisionless coupling between explosive debris plasma and magnetized ambient plasma

    NASA Astrophysics Data System (ADS)

    Bondarenko, A. S.; Schaeffer, D. B.; Everson, E. T.; Clark, S. E.; Lee, B. R.; Constantin, C. G.; Vincena, S.; Van Compernolle, B.; Tripathi, S. K. P.; Winske, D.; Niemann, C.

    2017-08-01

    The explosive expansion of a localized plasma cloud into a relatively tenuous, magnetized, ambient plasma characterizes a variety of astrophysical and space phenomena. In these rarified environments, collisionless electromagnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the expanding "debris" plasma to the surrounding ambient plasma. In an effort to better understand the detailed physics of collisionless coupling mechanisms, compliment in situ measurements of space phenomena, and provide validation of previous computational and theoretical work, the present research jointly utilizes the Large Plasma Device and the Raptor laser facility at the University of California, Los Angeles to study the super-Alfvénic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and a magnetic flux probe. Doppler shifts detected in a He1+ ion spectral line indicate that the ambient ions initially accelerate transverse to both the debris plasma flow and the background magnetic field. A qualitative analysis in the framework of a "hybrid" plasma model (kinetic ions and inertia-less fluid electrons) demonstrates that the ambient ion trajectories are consistent with the large-scale laminar electric field expected to develop due to the expanding debris. In particular, the transverse ambient ion motion provides direct evidence of Larmor coupling, a collisionless momentum exchange mechanism that has received extensive theoretical and numerical investigation. In order to quantitatively evaluate the observed Doppler shifts, a custom simulation utilizing a detailed model of the laser-produced debris plasma evolution calculates the laminar electric field and computes the initial response of a distribution of ambient test ions. A synthetic Doppler

  4. Spectroscopic Measurements of Collision-less Coupling Between Explosive Debris Plasmas and Ambient, Magnetized Background Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Everson, Erik; Vincena, Stephen; van Compernolle, Bart; Constantin, Carmen; Clark, Eric; Niemann, Christoph

    2013-10-01

    Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between explosive debris plasmas and ambient, magnetized background plasmas of astrophysical relevance. In recent campaigns on the Large Plasma Device (LAPD) (nelec =1012 -1013 cm-3, Telec ~ 5 eV, B0 = 200 - 400 G) utilizing the new Raptor laser facility (1053 nm, 100 J per pulse, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within ambient, magnetized helium background plasmas and prominent spectral lines of carbon and helium ions were studied in high spectral (0 . 01 nm) and temporal (50 ns) resolution. Time-resolved velocity components extracted from Doppler shift measurements of the C+4 227 . 1 nm spectral line along two perpendicular axes reveal significant deceleration as the ions stream and gyrate within the helium background plasma, indicating collision-less momentum coupling. The He+1 320 . 3 nm and 468 . 6 nm spectral lines of the helium background plasma are observed to broaden and intensify in response to the carbon debris plasma, indicative of strong electric fields (Stark broadening) and energetic electrons. The experimental results are compared to 2D hybrid code simulations.

  5. Component Framework for Coupled Integrated Fusion Plasma Simulation

    SciTech Connect

    Elwasif, Wael R; Bernholdt, David E; Berry, Lee A; Batchelor, Donald B

    2007-01-01

    Fusion Successful simulation of the complex physics that affect magnetically confined fusion plasma remains an important target milestone towards the development of viable fusion energy. Major advances in the underlying physics formulations, mathematical modeling, and computational tools and techniques are needed to enable a complete fusion simulation on the emerging class of large scale capability parallel computers that are coming on-line in the next few years. Several pilot projects are currently being undertaken to explore different (partial) code integration and coupling problems, and possible solutions that may guide the larger integration endeavor. In this paper, we present the design and implementation details of one such project, a component based approach to couple existing codes to model the interaction between high power radio frequency (RF) electromagnetic waves, and magnetohydrodynamics (MHD) aspects of the burning plasma. The framework and component design utilize a light coupling approach based on high level view of constituent codes that facilitates rapid incorporation of new components into the integrated simulation framework. The work illustrates the viability of the light coupling approach to better understand physics and stand-alone computer code dependencies and interactions, as a precursor to a more tightly coupled integrated simulation environment.

  6. Study on spatial distribution of plasma parameters in a magnetized inductively coupled plasma

    SciTech Connect

    Cheong, Hee-Woon; Lee, Woohyun; Kim, Ji-Won; Whang, Ki-Woong; Kim, Hyuk; Park, Wanjae

    2015-07-15

    Spatial distributions of various plasma parameters such as plasma density, electron temperature, and radical density in an inductively coupled plasma (ICP) and a magnetized inductively coupled plasma (M-ICP) were investigated and compared. Electron temperature in between the rf window and the substrate holder of M-ICP was higher than that of ICP, whereas the one just above the substrate holder of M-ICP was similar to that of ICP when a weak (<8 G) magnetic field was employed. As a result, radical densities in M-ICP were higher than those in ICP and the etch rate of oxide in M-ICP was faster than that in ICP without severe electron charging in 90 nm high aspect ratio contact hole etch.

  7. Strong Coupling Effects on Bound States in Plasmas.

    DTIC Science & Technology

    1985-02-01

    inverse Debye length; strong coupling means r P 1 or y > 1. In the systems of interest y m 1 20. For this reason, conventional perturbation approaches do...using one of the strongly coupled static plasma schemes-either the mean field theories , or HNC. - Finally X is to be determined by calculating the free...energy of the system and minimizing it with respect to X. The salient feature of this scheme is that it applies the philosophy of the TF-DH ( Debye

  8. Solid sampling electrothermal vaporization for sample introduction in inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Moens, L.; Verrept, P.; Boonen, S.; Vanhaecke, F.; Dams, R.

    1995-06-01

    Solid sampling using electrothermal vaporization is an attractive sample introduction method for atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). For AAS, the method is well established. The techniques needed to apply SS-ETV in ICP-based methods are described, with the emphasis on the coupling of different types of ETV-devices to the inductively coupled plasma torch and on the requirements for the spectrometer and the data acquisition and handling system. Though standardization is not straightforward, it is shown that standard addition and external calibration with solid standards yield accurate results. The latter is demonstrated by the analysis of standard reference materials. Figures of merit for SS-ETV-ICP-AES and SS-ETV-ICP-MS are presented. The literature concerning ICP-AES and ICP-MS (methods and applications) is briefly reviewed and new results of SS-ETV-ICP-MS analysis of SRMs are presented.

  9. Extraction of negative ions from pulsed electronegative capacitively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Rauf, Shahid; Collins, Ken

    2012-08-01

    Charge buildup during plasma etching of dielectric features can lead to undesirable effects, such as notching, bowing, and twisting. Pulsed plasmas have been suggested as a method to achieve charge-free plasma etching. In particular, electronegative plasmas are attractive as the collapse of the plasma potential during the after-glow period of pulsed capacitively coupled plasmas (CCPs) can allow for extraction of negative ions into the feature. The extraction of negative ions in the after-glow of pulsed CCPs sustained in CF{sub 4} containing gas mixtures is computationally investigated. In this paper, the consequences of pulse frequency and gas chemistry on negative ion flux to the wafer are discussed. A low negative ion flux to the wafer was observed only in the late after-glow period of low pulse frequencies. The negative ion flux was found to significantly increase with the addition of highly electronegative gases (such as thermally attaching Cl{sub 2}) even at a high pulse frequency of 10 kHz. As the production of negative ions during the after-glow diminishes, alternative strategies to enhance the flux were also pursued. The flux of negative ions was found to increase by the addition of a pulsed dc voltage on the top electrode that is 180 Degree-Sign out-of-phase with the rf pulse.

  10. H-mode inductive coupling plasma for PVC surface treatment

    NASA Astrophysics Data System (ADS)

    Croccolo, F.; Quintini, A.; Barni, R.; Ripamonti, M.; Malgaroli, A.; Riccardi, C.

    2009-08-01

    An inductively coupled plasma machine has been modified to be able to apply working powers in the order of 1 kW, thus switching to the real inductive H-mode. The plasma is generated by applying a 13.56 MHz radio-frequency to a λ/4 antenna outside the plasma chamber in low pressure conditions. The working gas is argon at pressure in the range from 10 to 100 Pa. With this high power source we have been able to perform plasma etching on a poly(vinyl-chloride) (PVC) film. In particular the effect of the plasma is the selective removal of hydrogen and chlorine from the sample surface. The action of the high power plasma on the sample has been proved to be much more effective than that of the low power one. Results similar to those obtained with the low power machine at about 300 W for 120 min, have been obtained with the high power source at about 600 W for 30 min. The superficial generation of a conductive layer of double C=C bonds was obtained. The samples have been investigated by means of ATR spectroscopy, FIB/SEM microscopy and micro-electrical measurements, which revealed the change in charge conductivity.

  11. Modified Enskog kinetic theory for strongly coupled plasmas.

    PubMed

    Baalrud, Scott D; Daligault, Jérôme

    2015-06-01

    Concepts underlying the Enskog kinetic theory of hard-spheres are applied to include short-range correlation effects in a model for transport coefficients of strongly coupled plasmas. The approach is based on an extension of the effective potential transport theory [S. D. Baalrud and J. Daligault, Phys. Rev. Lett. 110, 235001 (2013)] to include an exclusion radius surrounding individual charged particles that is associated with Coulomb repulsion. This is obtained by analogy with the finite size of hard spheres in Enskog's theory. Predictions for the self-diffusion and shear viscosity coefficients of the one-component plasma are tested against molecular dynamics simulations. The theory is found to accurately capture the kinetic contributions to the transport coefficients, but not the potential contributions that arise at very strong coupling (Γ≳30). Considerations related to a first-principles generalization of Enskog's kinetic equation to continuous potentials are also discussed.

  12. Ionized PVD with an Inductively Coupled Plasma Source

    NASA Astrophysics Data System (ADS)

    Hayden, D. B.; Juliano, D. R.; Ruzic, D. N.

    1997-10-01

    Ionized physical vapor deposition (iPVD) is used to enhance the directionality of metal deposition. This is a potential solution to depositing into higher aspect-ratio trenches and vias for metal interconnects. A dc magnetron (Donated by Materials Research Corporation) is coupled with an inductively coupled plasma (ICP) coil to increase the ionization of the sputtered metal atoms. This allows metal ions to be accelerated across the plasma sheath to a biased substrate and deposited normally. One coil design has a wider diameter than the substrate to reduce shadowing and flaking effects. Argon and neon working gases and aluminum and copper targets are investigated at varying pressures and power levels. Deposition rates and metal flux ionization fractions are measured with a quartz crystal microbalance and a multi-grid analyzer.

  13. CAPILLARY ELECTROPHORESIS COUPLED ON-LINE WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY FOR ELEMENTAL SPECIATION

    EPA Science Inventory

    A novel interface to connect a capillary electrophoresis (CE) system with an inductively coupled plasma mass spectrometric (ICPMS) detector is reported here. The interface was built using a direct injection nebulizer (DIN) system. In this interface, the CE capillary was placed co...

  14. CAPILLARY ELECTROPHORESIS COUPLED ON-LINE WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY FOR ELEMENTAL SPECIATION

    EPA Science Inventory

    A novel interface to connect a capillary electrophoresis (CE) system with an inductively coupled plasma mass spectrometric (ICPMS) detector is reported here. The interface was built using a direct injection nebulizer (DIN) system. In this interface, the CE capillary was placed co...

  15. Parametric investigations of plasma characteristics in a remote inductively coupled plasma system

    NASA Astrophysics Data System (ADS)

    Shukla, Prasoon; Roy, Abhra; Jain, Kunal; Bhoj, Ananth

    2016-09-01

    Designing a remote plasma system involves source chamber sizing, selection of coils and/or electrodes to power the plasma, designing the downstream tubes, selection of materials used in the source and downstream regions, locations of inlets and outlets and finally optimizing the process parameter space of pressure, gas flow rates and power delivery. Simulations can aid in spatial and temporal plasma characterization in what are often inaccessible locations for experimental probes in the source chamber. In this paper, we report on simulations of a remote inductively coupled Argon plasma system using the modeling platform CFD-ACE +. The coupled multiphysics model description successfully address flow, chemistry, electromagnetics, heat transfer and plasma transport in the remote plasma system. The SimManager tool enables easy setup of parametric simulations to investigate the effect of varying the pressure, power, frequency, flow rates and downstream tube lengths. It can also enable the automatic solution of the varied parameters to optimize a user-defined objective function, which may be the integral ion and radical fluxes at the wafer. The fast run time coupled with the parametric and optimization capabilities can add significant insight and value in design and optimization.

  16. Bulk molybdenum field emitters by inductively coupled plasma etching.

    PubMed

    Zhu, Ningli; Cole, Matthew T; Milne, William I; Chen, Jing

    2016-12-07

    In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realised for masks consisting of aperture arrays some 4.45 μm in diameter and whose field electron emission performance has been herein assessed.

  17. Quantum simulations of strongly coupled quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2012-06-01

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasi-particles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the classical molecular dynamics by Gelman, Shuryak, and Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state. The results indicate that the QGP reveals liquid-like rather than gaslike properties. Quantum effects turned out to be of prime importance in these simulations.

  18. Diagnostic studies of ion beam formation in inductively coupled plasma

    SciTech Connect

    Jacobs, Jenee L.

    2015-01-01

    This dissertation describes a variety of studies focused on the plasma and the ion beam in inductively coupled plasma mass spectrometry (ICP-MS). The ability to use ICP-MS for measurements of trace elements in samples requires the analytes to be efficiently ionized. Updated ionization efficiency tables are discussed for ionization temperatures of 6500 K and 7000 K with an electron density of 1 x 1015 cm-3. These values are reflective of the current operating parameters of ICP-MS instruments. Calculations are also discussed for doubly charged (M2+) ion formation, neutral metal oxide (MO) ionization, and metal oxide (MO+) ion dissociation for similar plasma temperature values. Ionization efficiency results for neutral MO molecules in the ICP have not been reported previously.

  19. Effective potential kinetic theory for strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Baalrud, Scott D.; Daligault, Jérôme

    2016-11-01

    The effective potential theory (EPT) is a recently proposed method for extending traditional plasma kinetic and transport theory into the strongly coupled regime. Validation from experiments and molecular dynamics simulations have shown it to be accurate up to the onset of liquid-like correlation parameters (corresponding to Γ ≃ 10-50 for the one-component plasma, depending on the process of interest). Here, this theory is briefly reviewed along with comparisons between the theory and molecular dynamics simulations for self-diffusivity and viscosity of the one-component plasma. A number of new results are also provided, including calculations of friction coefficients, energy exchange rates, stopping power, and mobility. The theory is also cast in the Landau and Fokker-Planck kinetic forms, which may prove useful for enabling efficient kinetic computations.

  20. Trace elements in seminal plasma of men from infertile couples

    PubMed Central

    Szynkowska, Małgorzata I.; Motak-Pochrzęst, Hanna; Pawlaczyk, Aleksandra; Sypniewski, Stanisław

    2015-01-01

    Introduction An analysis of lead, zinc, cadmium and other trace elements in semen of men from infertile couples was performed to determine the association between abnormal semen parameters and enviromental or occupational exposure to some trace metals. Material and methods Presence of manganese, cobalt, nickel, copper, zinc, molybdenum, cadmium, tin and lead was measured in seminal plasma of 34 men from infertile couples using spectrometry with time-of-flight analysis. Correlations among sperm parameters and trace metals were determined using cluster analysis and Pearson's correlation coefficient. Results Abnormally high concentrations of lead, cadmium, zinc and cobalt were found in 23 seminal plasma of men from infertile couples. The most consistent evidence was determined for an association between high cadmium concentration in seminal plasma and sperm count, motility and morphology below reference limits (p < 0.01). A correlation of significantly increased tin level and reduced sperm count in semen of men with limited fertility potential was observed (p = 0.04). Conclusions In our study we observed a correlation of tin level with sperm count in semen of men with limited fertility potential. PMID:26170853

  1. Synthesis of Silicon Nanoparticles in Inductively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Markosyan, Aram H.; Le Picard, Romain; Girshick, Steven L.; Kushner, Mark J.

    2016-09-01

    The synthesis of silicon nanoparticles (Si-NPs) is being investigated for their use in photo-emitting electronics, photovoltaics, and biotechnology. The ability to control the size and mono-disperse nature of Si-NPs is important to optimizing these applications. In this paper we discuss results from a computational investigation of Si-NP formation and growth in an inductively coupled plasma (ICP) reactor with the goal of achieving this control. We use a two dimensional numerical model where the algorithms for the kinetics of NP formation are self-consistently coupled with a plasma hydrodynamics simulation. The reactor modeled here resembles a GEC reference cell through which, for the base case, a mixture of Ar/SiH4 = 70/30 flows at 150 sccm at a pressure of 100 mTorr. In continuous wave mode, three coils located on top of the reactor deliver 150 W. The electric plasma potential confines negatively charged particles at the center of the discharge, increasing the residence time of negative NPs, which enables the NPs to potentially grow to large and controllable sizes of many to 100s nm. We discuss methods of controlling NP growth rates by varying the mole fraction and flow rate of SiH4, and using a pulsed plasma by varying the pulse period and duty cycle. Work supported by DOE Office of Fusion Energy Science and National Science Foundation.

  2. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan; Katsouros, Joseph

    1999-11-01

    We measure the electrical conductivity of strongly coupled plasmas of various metals, including aluminum, iron, copper, and tungsten, in the temperature range 6-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. These plasmas may have coupling parameters (ratio of mean interparticle Coulomb energy to mean kinetic energy) ranging from as high as 50 down to unity. Plasmas are created by rapid vaporization of metal wire in a water bath which act as a tamper. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL SESAME database [1], and a brightness temperature may be obtained from radiation measurements. The column resistance is determined from time-resolved voltage and current measurements. Results of conductivity measurements will be shown and compared with the predictions of conductivity theories. 1.SESAME: The Los Alamos National Laboratory Equation of State Database, Report LA-UR-92-3407, ed. S. P. Lyon and J. D. Johnson, Group T-1.

  3. Numerical modeling of strongly-coupled dusty plasma systems

    NASA Astrophysics Data System (ADS)

    Vasut, John Anthony

    2001-09-01

    Plasma systems occur in a variety of astrophysical and laboratory environments. Often these systems contain a dust component in addition to the plasma particles. Plasmas are generally regarded as a highly disordered state of matter and dust is often seen as a contaminant to the plasma. However, in ``strongly coupled'' dusty plasmas where the electrical potential energy between the dust particles is higher than the average kinetic energy of the particles, it is possible for the system to exist in a ``liquid'' or ``crystalline'' state. The first such crystalline states were observed experimentally in 1994 and are not yet fully understood. The spacing between the particles is typically around 100 microns, allowing the individual particles to be visually observed and tracked. Several computer models have suggested that the amount of ordering present in the system should depend only upon two dimensionless parameters: the ratio of the electrical energy to the kinetic energy and the ratio of the interparticle separation to the Debye length of the plasma. These models suggest that the method in which these two parameters are reached should have no impact upon the amount of order within the system. The results of computer modeling using a tree code known as Box_Tree, which, unlike most other computer simulations, includes all interparticle interactions, shows that the method by which these parameters are reached does have an affect on the final state of the system. Box_Tree has also been used to study Mach cones caused by particles traveling through or near a dust crystal. In addition, preliminary results on the study of finite dusty plasma systems have been obtained. These results show that particles confined in a finite plasma oscillate with a frequency that depends upon particle mass and charge.

  4. Numerical Experiments In Strongly Coupled Complex (Dusty) Plasmas

    NASA Astrophysics Data System (ADS)

    Hou, L. J.; Ivlev A.; Hubertus M. T.; Morfill, G. E.

    2010-07-01

    Complex (dusty) plasma is a suspension of micron-sized charged dust particles in a weakly ionized plasma with electrons, ions, and neutral atoms or molecules. Therein, dust particles acquire a few thousand electron charges by absorbing surrounding electrons and ions, and consequently interact with each other via a dynamically screened Coulomb potential while undergoing Brownian motion due primarily to frequent collisions with the neutral molecules. When the interaction potential energy between charged dust particles significantly exceeds their kinetic energy, they become strongly coupled and can form ordered structures comprising liquid and solid states. Since the motion of charged dust particles in complex (dusty) plasmas can be directly observed in real time by using a video camera, such systems have been generally regarded as a promising model system to study many phenomena occurring in solids, liquids and other strongly-coupled systems at the kinetic level, such as phase transitions, transport processes, and collective dynamics. Complex plasma physics has now grown into a mature research field with a very broad range of interdisciplinary facets. In addition to usual experimental and theoretical study, computer simulation in complex plasma plays an important role in bridging experimental observations and theories and in understanding many interesting phenomena observed in laboratory. The present talk will focus on a class of computer simulations that are usually non-equilibrium ones with external perturbation and that mimic the real complex plasma experiments (i. e., numerical experiment). The simulation method, i. e., the so-called Brownian Dynamics methods, will be firstly reviewed and then examples, such as simulations of heat transfer and shock wave propagation, will be present.

  5. Coupling strength in Coulomb and Yukawa one-component plasmas

    SciTech Connect

    Ott, T.; Bonitz, M.; Stanton, L. G.; Murillo, M. S.

    2014-11-15

    In a non-ideal classical Coulomb one-component plasma (OCP), all thermodynamic properties are known to depend only on a single parameter—the coupling parameter Γ. In contrast, if the pair interaction is screened by background charges (Yukawa OCP) the thermodynamic state depends, in addition, on the range of the interaction via the screening parameter κ. How to determine in this case an effective coupling parameter has been a matter of intensive debate. Here we propose a consistent approach for defining and measuring the coupling strength in Coulomb and Yukawa OCPs based on a fundamental structural quantity, the radial pair distribution function (RPDF). The RPDF is often accessible in experiments by direct observation or indirectly through the static structure factor. Alternatively, it is directly computed in theoretical models or simulations. Our approach is based on the observation that the build-up of correlation from a weakly coupled system proceeds in two steps: First, a monotonically increasing volume around each particle becomes devoid of other particles (correlation hole), and second (upon further increase of the coupling), a shell structure emerges around each particle giving rise to growing peaks of the RPDF. Using molecular dynamics simulation, we present a systematic study for the dependence of these features of the RPDF on Γ and κ and derive a simple expression for the effective coupling parameter.

  6. Characterization of high-pressure capacitively coupled hydrogen plasmas

    SciTech Connect

    Nunomura, S.; Kondo, M.

    2007-11-01

    Capacitively coupled very-high-frequency hydrogen plasmas have been systematically diagnosed in a wide range of a gas pressure from 5 mTorr to 10 Torr. The plasma parameters, ion species, and ion energy distributions (IEDs) are measured using a Langmuir probe, optical emission spectroscopy, and energy filtered mass spectrometer. The measurement results show that the ion species in a hydrogen plasma is determined from ionization channels and subsequent ion-molecule reactions. The ions are dominated by H{sub 2}{sup +} at a less-collisional condition of < or approx. 20 mTorr, whereas those are dominated by H{sub 3}{sup +} at a collisional condition of > or approx. 20 mTorr. The IED is determined by both the sheath potential drop and ion-neutral collisions in the plasma sheath. The IED is broadened for a collisional sheath at > or approx. 0.3 Torr and the ion bombardment energy is lowered. For high-pressure discharge operated at {approx_equal}10 Torr, plasmas are characterized by a low electron temperature of {approx_equal}0.8 eV and a low ion bombardment energy of < or approx. 15 eV.

  7. Inductively coupled plasmas: Optimizing the inductive-coupling efficiency for large-area source design

    SciTech Connect

    Colpo, P.; Meziani, T.; Rossi, F.

    2005-03-01

    An inductively coupled plasma (ICP) source enabling high-density plasma generation was developed for large area processing. Technological difficulties related to the scaling up of the coil antenna, dielectric vacuum window, and gas distribution have been addressed. The proposed solution consists in using a magnetic core to concentrate the magnetic field produced by the antenna. Both are placed within the plasma chamber, and the gas injection is done through the magnetic pole. A 75x72- cm{sup 2} plasma source has been designed based on this solution. First, the electrical operation and coil geometries were optimized. The results show that the use of a low excitation frequency (2 MHz) increases the electrical efficiency of the magnetic core, enabling a higher plasma-density generation than at the classical radio frequency of 13.56 MHz. The antenna configuration providing the better uniformity is composed of three loops connected in parallel. Some tuning inductances in series with each loop were added to balance the rf power, i.e., the plasma density over the reactor area. Deviation from plasma uniformities better than 12% over 60x60 cm{sup 2} were achieved. Preliminary SiO{sub 2} etching experiments with CF{sub 4} gas show that the etching uniformity deviation reaches 7% over 60x60 cm{sup 2} with etching rates larger than 150 nm/min. These results are very promising and open the way to the successful scale-up of ICP sources to large areas.

  8. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation

    PubMed Central

    2013-01-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution. PMID:23634893

  9. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation.

    PubMed

    Shuto, Mitsutoshi; Tomino, Fukumi; Ohmi, Hiromasa; Kakiuchi, Hiroaki; Yasutake, Kiyoshi

    2013-05-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution.

  10. Effect of capacitive coupling in a miniature inductively coupled plasma source

    SciTech Connect

    Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2012-11-01

    Two-dimensional axisymmetric particle-in-cell simulations with a Monte Carlo collision algorithm (PIC-MCC) have been conducted to investigate the effect of capacitive coupling in a miniature inductively coupled plasma source (mICP) by using two models: an inductive model and a hybrid model. The mICP is 3 mm in radius and 6 mm in height with a three-turn planar coil, where argon plasma is sustained. In the inductive model, the coil is assumed to be electrostatically shielded, and thus the discharge is purely inductive coupling. In the hybrid model, we assume that the different turns of the coil act like electrodes in capacitive discharge to include the effect of capacitive coupling. The voltage applied to these electrodes decreases linearly from the powered end of the coil towards the grounded end. The numerical analysis has been performed for rf frequencies in the range of 100-1000 MHz, and the power absorbed by the plasma in the range of 5-50 mW at a fixed pressure of 500 mTorr. The PIC-MCC results show that potential oscillations at the plasma-dielectric interface are not negligible, and thus the major component of the absorbed power is caused by the axial motion of electrons in the hybrid model, although almost all of the power absorption is due to the azimuthal motion of electrons in the inductive model. The effect of capacitive coupling is more significant at lower rf frequencies and at higher absorbed powers under the calculation conditions examined. Moreover, much less coil currents are required in the hybrid model.

  11. Impact of Screening and Ionization on Coulomb Coupling in Strongly Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Stanton, Liam; Murillo, Michael; Cimarron Project Collaboration

    2013-10-01

    Coulomb coupling is traditionally defined by the parameter Γ =Q2 / aT , which is the ratio of a potential energy Q2 / a (Q is the charge and a is the spacing) to a kinetic energy T (T is the temperature in energy units). We examine regimes of strong coupling in dense plasma experiments using a refined definition in which we compute the potential and kinetic energies directly from their thermodynamic definition and include the effects of finite ionization and screening, which have recently been shown to have important impacts on coupling. We propose optimal experimental regimes that can be probed with XRTS to examine directly the physics of strong coupling. Prepared by LLNL under Contract DE-AC52-07NA27344.

  12. Turbulence in strongly coupled dusty plasmas using generalized hydrodynamic description

    SciTech Connect

    Tiwari, Sanat Kumar; Dharodi, Vikram Singh; Das, Amita; Patel, Bhavesh G.; Kaw, Predhiman

    2015-02-15

    The properties of decaying turbulence have been studied with the help of a Generalized Hydrodynamic (GHD) fluid model in the context of strongly coupled dusty plasma medium in two dimensions. The GHD model treats the strongly coupled dusty plasma system as a visco-elastic medium. The incompressible limit of the GHD model is considered here. The studies carried out here are, however, applicable to a wider class of visco-elastic systems, and are not merely confined to the dusty plasma medium. Our simulations studies show that an initial spectrum that is confined in a limited domain of wave numbers becomes broad, even when the Reynold's number is much less than the critical value required for the onset of turbulence in Newtonian fluids. This is a signature of elastic turbulence, where Weissenberg's number also plays an important role on the onset of turbulence. This feature has been observed in several experiments. It is also shown that the existence of memory relaxation time parameter and the transverse shear wave inhibit the normal process (for 2-D systems) of inverse spectral cascade in this case. A detailed simulation study has been carried out for the understanding of this inhibition.

  13. Coupling dispersive liquid-liquid microextraction to inductively coupled plasma atomic emission spectrometry: An oxymoron?

    PubMed

    Martínez, David; Torregrosa, Daniel; Grindlay, Guillermo; Gras, Luis; Mora, Juan

    2018-01-01

    Coupling dispersive liquid-liquid micro-extraction (DLLME) to inductively coupled plasma atomic emission spectrometry (ICP-AES) is usually troublesome due to the limited plasma tolerance to the organic solvents usually employed for metal extraction. This work explores different coupling strategies allowing the multi-element determination by ICP-AES of the solutions obtained after DLLME procedures. To this end, three of the most common extractant solvents in DLLME procedures (1-undecanol, 1-butyl-3-methyl-imidazolium hexafluorophosphate and chloroform) have been selected to face most of the main problems reported in DLLME-ICP-AES coupling (i.e., those arising from the high solvent viscosity and volatility). Results demonstrate that DLLME can be successfully coupled to ICP-AES after a careful optimization of the experimental conditions. Thus, elemental analysis in 1-undecanol and 1-butyl-3-methyl-imidazolium hexafluorophosphate extracts can be achieved by ICP-AES after a simple dilution step with methanol (1:0.5). Chloroform can be directly introduced into the plasma with minimum changes in the ICP-AES configuration usually employed when operating with aqueous solutions. Diluted inorganic acid solutions (1% w w(-1) either nitric or hydrochloric acids) have been successfully tested for the first time as a carrier for the introduction of organic extractants in ICP-AES. The coupling strategies proposed have been successfully applied to the multi-element analysis (Al, Cu, Fe, Mn, Ni and Zn) of different water samples (i.e. marine, tap and river) by DLLME-ICP-AES. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. A CF4 TPC to measure the ν¯e magnetic moment at a nuclear reactor.

    NASA Astrophysics Data System (ADS)

    Broggini, C.; Jörgens, V.; Treichel, M.; Twerenbold, D.; Vuilleumier, J.-L.

    An experiment is described which offers a significant improvement for the measurement of the ν¯ee- cross section at low energy. The experiment will be sensitive to a neutrino magnetic moment down to a few 10-11 Bohr magnetons, on the level of that introduced to explain the solar neutrino puzzle. The detector, to be placed close to a nuclear reactor, is a 1 m3 Time Pojection Chamber surrounded by an active shielding. The key point of the experiment is the use of tetrafluoromethane, CF4, at the pressure of 5 bar in the TPC.

  15. Space- and Time-dependent electron velocity distribution in VHF-CCP in CF4/Ar

    NASA Astrophysics Data System (ADS)

    Yagisawa, Takashi; Makabe, Toshiaki

    2009-10-01

    The electron velocity distribution (EVD) is fundamentally important for all aspects in plasma electronics. EVD given as a solution of the Boltzmann equation provides the swarm parameter as functions of external E/N and B/N utilized for a plasma simulation. Two-term expansion was traditionally employed for solving the Boltzmann equation. This method, however, cannot give EVD in a large E/N appearing in the ion sheath region in front of a wall surface. Particle simulation (PIC/MC) was also used to estimate EVD, but heavy computational load prohibits the sample of a large number of particles in order to eliminate the statistical fluctuation. A solution of the Boltzmann equation in phase space (velocity, position-space, and time) intrinsically involves numerical diffusion resulting from the differenciation of the advection terms. In this study, we develop the numerical procedure for predicting space- and time-dependent EVD. That is, the Boltzmann equation is solved in velocity space by using our direct numerical procedure (DNP) under the presence of 2D-t electric field distribution in VHF-CCP, calculated by the RCT model. Nonlinear behavior of EVD in the bulk plasma during one cycle of VHF (100 MHz) is discussed depending on the collisional relaxation time for energy and momentum of electrons. Also, we will investigate the temporal change of EVD in the sheath region under a large E/N.

  16. Development of 40 MHz inductively coupled plasma source and frequency effects on plasma parameters

    NASA Astrophysics Data System (ADS)

    Jun, Hyun-Su; Chang, Hong-Young

    2008-01-01

    A large-area inductively coupled plasma (ICP) source capable of securing azimuthal plasma uniformity at a 40.00MHz has been developed. The antenna, referred to as a capacitor distributed resonance antenna, minimizes the azimuthally nonuniform antenna capacitive field with eight distributed vertical capacitors. The antenna was designed to maximize the antenna current using L-C series resonance. Based on plasma diagnostics with a 13.56MHz conventional ICP, comparative analyses were performed in terms of the plasma density, electron temperature, and frequency characteristics of the electron energy probability function (EEPF). In addition, the frequency dependency of the EEPF was found in the collisional (νen>ω ), normal skin [vth/δ≪(ω2+νen2)1/2] regime and the physical causes of were examined.

  17. Multistage coupling of independent laser-plasma accelerators.

    PubMed

    Steinke, S; van Tilborg, J; Benedetti, C; Geddes, C G R; Schroeder, C B; Daniels, J; Swanson, K K; Gonsalves, A J; Nakamura, K; Matlis, N H; Shaw, B H; Esarey, E; Leemans, W P

    2016-02-11

    Laser-plasma accelerators (LPAs) are capable of accelerating charged particles to very high energies in very compact structures. In theory, therefore, they offer advantages over conventional, large-scale particle accelerators. However, the energy gain in a single-stage LPA can be limited by laser diffraction, dephasing, electron-beam loading and laser-energy depletion. The problem of laser diffraction can be addressed by using laser-pulse guiding and preformed plasma waveguides to maintain the required laser intensity over distances of many Rayleigh lengths; dephasing can be mitigated by longitudinal tailoring of the plasma density; and beam loading can be controlled by proper shaping of the electron beam. To increase the beam energy further, it is necessary to tackle the problem of the depletion of laser energy, by sequencing the accelerator into stages, each powered by a separate laser pulse. Here, we present results from an experiment that demonstrates such staging. Two LPA stages were coupled over a short distance (as is needed to preserve the average acceleration gradient) by a plasma mirror. Stable electron beams from a first LPA were focused to a twenty-micrometre radius--by a discharge capillary-based active plasma lens--into a second LPA, such that the beams interacted with the wakefield excited by a separate laser. Staged acceleration by the wakefield of the second stage is detected via an energy gain of 100 megaelectronvolts for a subset of the electron beam. Changing the arrival time of the electron beam with respect to the second-stage laser pulse allowed us to reconstruct the temporal wakefield structure and to determine the plasma density. Our results indicate that the fundamental limitation to energy gain presented by laser depletion can be overcome by using staged acceleration, suggesting a way of reaching the electron energies required for collider applications.

  18. The Importance of Optical Pathlength Control for Plasma Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.; Partridge, Harry (Technical Monitor)

    2001-01-01

    An inductively coupled GEC Cell with modified viewing ports has been used to measure in-situ absorption in CF4 plasmas via Fourier Transform Infrared Spectroscopy, and the results compared to those obtained in a standard viewport configuration. The viewing ports were modified so that the window boundary is inside, rather than outside, of the GEC cell. Because the absorption obtained is a spatially integrated absorption, measurements made represent an averaging of absorbing species inside and outside of the plasma. This modification is made to reduce this spatial averaging and thus allow a more accurate estimation of neutral species concentrations and temperatures within the plasmas. By reducing this pathlength, we find that the apparent CF4 consumption increases from 65% to 95% and the apparent vibrational temperature of CF4 rises by 50-75 K. The apparent fraction of etch product SiF4 decreases from 4% to 2%. The data suggests that these density changes may be due to significant temperature gradients between the plasma and chamber viewports.

  19. Quark Gluon Plasma: Surprises from strongly coupled QCD matter

    NASA Astrophysics Data System (ADS)

    Jacak, Barbara

    2017-01-01

    Quantum Chromodynamics has long predicted a transition from normal hadronic matter to a phase where the quarks and gluons are no longer bound together and can move freely. Quark gluon plasma is now produced regularly in collisions of heavy nuclei at very high energy at both the Relativistic Heavy Ion Collider (RHIC) in the U.S. and at the LHC in Europe. Quark gluon plasma exhibits remarkable properties. Its vanishingly small shear viscosity to entropy density ratio means that it flows essentially without internal friction, making it one of the most ``perfect'' liquids known. It is also very opaque to transiting particles including heavy charm quarks, though the exact mechanism for this is not yet understood. Recent data suggest that even very small colliding systems may produce a droplet of plasma. The similarities to strongly coupled or correlated systems in ultra-cold atoms and condensed matter are striking, and have inspired novel theoretical descriptions growing out of string theory. It remains a mystery how this plasma emerges from cold, dense gluonic matter deep inside nuclei. I will discuss how a future electron-ion collider can help address this question.

  20. Tiling analysis of melting in strongly-coupled dusty plasma*

    NASA Astrophysics Data System (ADS)

    Suranga Ruhunusiri, W. D.; Feng, Yan; Liu, Bin; Goree, John

    2010-11-01

    A dusty plasma is an ionized gas containing micron-size particles of solid matter, which collect electrons and ions and become negatively charged. Due to large Coulomb interparticle potential energies, the microparticles represent a strongly-coupled plasma. In the absence of an external disturbance, the microparticles self-organize, arranging themselves in a crystalline lattice, due to their Coulomb interaction. If kinetic energy is added, the arrangement of microparticles becomes disordered, like atoms in a liquid. This melting process can be characterized by a proliferation of defects, which previous experimenters measured using Voronoi analysis. Here we use another method, tiling [1] to quantify defects. We demonstrate this method, which until now has been used only in simulations, in a dusty plasma experiment. A single layer of 4.83 μm polymer microparticles was electrically levitated in a glow discharge argon plasma. The lattice was melted by applying random kicks to the micoparticles from rastered laser beams. We imaged the particle positions and computed the corresponding tiling for both the crystalline lattice and liquid states. [1] Matthew A. Glaser, Phys. Rev A 41, 4585 (1990) ^*Work supported by NSF and NASA.

  1. Strong-coupling effects in a plasma of confining gluons

    NASA Astrophysics Data System (ADS)

    Florkowski, Wojciech; Ryblewski, Radoslaw; Su, Nan; Tywoniuk, Konrad

    2016-12-01

    The plasma consisting of confining gluons resulting from the Gribov quantization of the SU(3) Yang-Mills theory is studied using non-equilibrium fluid dynamical framework. Exploiting the Bjorken symmetry and using linear response theory a general analytic expressions for the bulk, ζ, and shear, η, viscosity coefficients are derived. It is found that the considered system exhibits a number of properties similar to the strongly-coupled theories, where the conformality is explicitly broken. In particular, it is shown that, in the large temperature limit, ζ / η ratio, scales linearly with the difference 1 / 3 - cs2, where cs is the speed of sound. Results obtained from the analysis are in line with the interpretation of the quark-gluon plasma as an almost perfect fluid.

  2. The energetic coupling of scales in gyrokinetic plasma turbulence

    SciTech Connect

    Teaca, Bogdan; Jenko, Frank

    2014-07-15

    In magnetized plasma turbulence, the couplings of perpendicular spatial scales that arise due to the nonlinear interactions are analyzed from the perspective of the free-energy exchanges. The plasmas considered here, with appropriate ion or electron adiabatic electro-neutrality responses, are described by the gyrokinetic formalism in a toroidal magnetic geometry. Turbulence develops due to the electrostatic fluctuations driven by temperature gradient instabilities, either ion temperature gradient (ITG) or electron temperature gradient (ETG). The analysis consists in decomposing the system into a series of scale structures, while accounting separately for contributions made by modes possessing special symmetries (e.g., the zonal flow modes). The interaction of these scales is analyzed using the energy transfer functions, including a forward and backward decomposition, scale fluxes, and locality functions. The comparison between the ITG and ETG cases shows that ETG turbulence has a more pronounced classical turbulent behavior, exhibiting a stronger energy cascade, with implications for gyrokinetic turbulence modeling.

  3. The energetic coupling of scales in gyrokinetic plasma turbulence

    NASA Astrophysics Data System (ADS)

    Teaca, Bogdan; Navarro, Alejandro Bañón; Jenko, Frank

    2014-07-01

    In magnetized plasma turbulence, the couplings of perpendicular spatial scales that arise due to the nonlinear interactions are analyzed from the perspective of the free-energy exchanges. The plasmas considered here, with appropriate ion or electron adiabatic electro-neutrality responses, are described by the gyrokinetic formalism in a toroidal magnetic geometry. Turbulence develops due to the electrostatic fluctuations driven by temperature gradient instabilities, either ion temperature gradient (ITG) or electron temperature gradient (ETG). The analysis consists in decomposing the system into a series of scale structures, while accounting separately for contributions made by modes possessing special symmetries (e.g., the zonal flow modes). The interaction of these scales is analyzed using the energy transfer functions, including a forward and backward decomposition, scale fluxes, and locality functions. The comparison between the ITG and ETG cases shows that ETG turbulence has a more pronounced classical turbulent behavior, exhibiting a stronger energy cascade, with implications for gyrokinetic turbulence modeling.

  4. Strongly coupled plasma with electric and magnetic charges

    SciTech Connect

    Liao Jinfeng; Shuryak, Edward

    2007-05-15

    A number of theoretical and lattice results lead us to believe that quark-gluon plasma not too far from T{sub c} contains not only electrically charged quasiparticles - quarks and gluons - but magnetically charged ones--monopoles and dyons--as well. Although binary systems such as charge-monopole and charge-dyon were considered in detail before in both classical and quantum settings, this is the first study of coexisting electric and magnetic particles in a many-body context. We perform a molecular dynamics study of strongly coupled plasmas with {approx}1000 particles and differing fractions of magnetic charge. Correlation functions and Kubo formulas lead to transport properties such as the diffusion constant, the shear viscosity, and electric conductivity: We compare the first two with empirical data from RHIC experiments as well as with results from anti-de-Sitter space/conformal field theory correspondence. We also study a number of collective excitations in these systems.

  5. Damping of hard excitations in strongly coupled N = 4 plasma

    NASA Astrophysics Data System (ADS)

    Fuini, John F.; Uhlemann, Christoph F.; Yaffe, Laurence G.

    2016-12-01

    The damping of high momentum excitations in strongly coupled maximally supersymmetric Yang-Mills plasma is studied. Previous calculations of the asymptotic behavior of the quasinormal mode spectrum are extended and clarified. We confirm that subleading corrections to the lightlike dispersion relation ω( q) = | q| have a universal | q|-1/3 form. Sufficiently narrow, weak planar shocks may be viewed as coherent superpositions of short wavelength quasinormal modes. The attenuation and evolution in profile of narrow planar shocks are examined as an application of our results.

  6. Nonlinear wave propagation in a strongly coupled collisional dusty plasma.

    PubMed

    Ghosh, Samiran; Gupta, Mithil Ranjan; Chakrabarti, Nikhil; Chaudhuri, Manis

    2011-06-01

    The propagation of a nonlinear low-frequency mode in a strongly coupled dusty plasma is investigated using a generalized hydrodynamical model. For the well-known longitudinal dust acoustic mode a standard perturbative approach leads to a Korteweg-de Vries (KdV) soliton. The strong viscoelastic effect, however, introduced a nonlinear forcing and a linear damping in the KdV equation. This novel equation is solved analytically to show a competition between nonlinear forcing and dissipative damping. The physical consequence of such a solution is also sketched.

  7. Nonlinear wave propagation in a strongly coupled collisional dusty plasma

    SciTech Connect

    Ghosh, Samiran; Gupta, Mithil Ranjan; Chakrabarti, Nikhil; Chaudhuri, Manis

    2011-06-15

    The propagation of a nonlinear low-frequency mode in a strongly coupled dusty plasma is investigated using a generalized hydrodynamical model. For the well-known longitudinal dust acoustic mode a standard perturbative approach leads to a Korteweg-de Vries (KdV) soliton. The strong viscoelastic effect, however, introduced a nonlinear forcing and a linear damping in the KdV equation. This novel equation is solved analytically to show a competition between nonlinear forcing and dissipative damping. The physical consequence of such a solution is also sketched.

  8. Charmonium in strongly coupled quark-gluon plasma

    SciTech Connect

    Young, Clint; Shuryak, Edward

    2009-03-15

    The growing consensus that a strongly coupled quark-gluon plasma (sQGP) has been observed at the SPS and RHIC experiments suggests a different framework for examining heavy-quark dynamics. We present both a semianalytical treatment of Fokker-Planck (FP) evolution in pedagogical examples and numerical Langevin simulations of evolving cc pairs on top of a hydrodynamically expanding fireball. In this way, we may conclude that the survival probability of bound charmonia states is greater than previously estimated, as the spatial equilibration of pairs proceeds through a 'slowly dissolving lump' stage related to the pair interaction.

  9. A double inductively coupled plasma for sterilization of medical devices

    NASA Astrophysics Data System (ADS)

    Halfmann, H.; Bibinov, N.; Wunderlich, J.; Awakowicz, P.

    2007-07-01

    A double inductively coupled low pressure plasma for sterilization of bio-medical materials is introduced. It is developed for homogeneous treatment of three-dimensional objects. The short treatment times and low temperatures allow the sterilization of heat sensitive materials like ultra-high-molecular-weight-polyethylene or polyvinyl chloride. Using a non-toxic atmosphere reduces the total process time in comparision with common methods. Langmuir probe measurements are presented to show the difference between ICP- and CCP-mode discharges, the spatial homogeneity and the influence on the sterilization efficiency. To know more about the sterilization mechanisms optical emission is measured and correlated with sterilization results.

  10. Measured pressure distributions, aerodynamic coefficients and shock shapes on blunt bodies at incidence in hypersonic air and CF4

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1982-01-01

    Pressure distributions, aerodynamic coefficients, and shock shapes were measured on blunt bodies of revolution in Mach 6 CF4 and in Mach 6 and Mach 10 air. The angle of attack was varied from 0 deg to 20 deg in 4 deg increments. Configurations tested were a hyperboloid with an asymptotic angle of 45 deg, a sonic-corner paraboloid, a paraboloid with an angle of 27.6 deg at the base, a Viking aeroshell generated in a generalized orthogonal coordinate system, and a family of cones having a 45 deg half-angle with spherical, flattened, concave, and cusp nose shapes. Real-gas effects were simulated for the hperboloid and paraboloid models at Mach 6 by testing at a normal-shock density ratio of 5.3 in air and 12 CF4. Predictions from simple theories and numerical flow field programs are compared with measurement. It is anticipated that the data presented in this report will be useful for verification of analytical methods for predicting hypersonic flow fields about blunt bodies at incidence.

  11. Transient plasma potential in pulsed dual frequency inductively coupled plasmas and effect of substrate biasing

    SciTech Connect

    Mishra, Anurag; Yeom, Geun Young

    2016-09-15

    An electron emitting probe in saturated floating potential mode has been used to investigate the temporal evolution of plasma potential and the effect of substrate RF biasing on it for pulsed dual frequency (2 MHz/13.56 MHz) inductively coupled plasma (ICP) source. The low frequency power (P{sub 2MHz}) has been pulsed at 1 KHz and a duty ratio of 50%, while high frequency power (P{sub 13.56MHz}) has been used in continuous mode. The substrate has been biased with a separate bias power at (P{sub 12.56MHz}) Argon has been used as a discharge gas. During the ICP power pulsing, three distinct regions in a typical plasma potential profile, have been identified as ‘initial overshoot’, pulse ‘on-phase’ and pulse ‘off-phase’. It has been found out that the RF biasing of the substrate significantly modulates the temporal evolution of the plasma potential. During the initial overshoot, plasma potential decreases with increasing RF biasing of the substrate, however it increases with increasing substrate biasing for pulse ‘on-phase’ and ‘off-phase’. An interesting structure in plasma potential profile has also been observed when the substrate bias is applied and its evolution depends upon the magnitude of bias power. The reason of the evolution of this structure may be the ambipolar diffusion of electron and its dependence on bias power.

  12. Transient plasma potential in pulsed dual frequency inductively coupled plasmas and effect of substrate biasing

    NASA Astrophysics Data System (ADS)

    Mishra, Anurag; Yeom, Geun Young

    2016-09-01

    An electron emitting probe in saturated floating potential mode has been used to investigate the temporal evolution of plasma potential and the effect of substrate RF biasing on it for pulsed dual frequency (2 MHz/13.56 MHz) inductively coupled plasma (ICP) source. The low frequency power (P2MHz) has been pulsed at 1 KHz and a duty ratio of 50%, while high frequency power (P13.56MHz) has been used in continuous mode. The substrate has been biased with a separate bias power at (P12.56MHz) Argon has been used as a discharge gas. During the ICP power pulsing, three distinct regions in a typical plasma potential profile, have been identified as `initial overshoot', pulse `on-phase' and pulse `off-phase'. It has been found out that the RF biasing of the substrate significantly modulates the temporal evolution of the plasma potential. During the initial overshoot, plasma potential decreases with increasing RF biasing of the substrate, however it increases with increasing substrate biasing for pulse `on-phase' and `off-phase'. An interesting structure in plasma potential profile has also been observed when the substrate bias is applied and its evolution depends upon the magnitude of bias power. The reason of the evolution of this structure may be the ambipolar diffusion of electron and its dependence on bias power.

  13. Electrical asymmetry effects in magnetized capacitively coupled plasmas in argon

    NASA Astrophysics Data System (ADS)

    Yang, Shali; Zhang, Ya; Wang, Hong-Yu; Wang, Shuai; Jiang, Wei

    2017-06-01

    Geometrically symmetric and electrically asymmetric discharges operating at 13.56 MHz and 27.12 MHz with variable phase angle between the harmonics are simulated by a one-dimensional implicit particle-in-cell/Monte Carlo collision model in argon at a pressure of 30 mTorr. The amplitude of each of the harmonics is chosen to be 150 V. The magnetic fields, with strengths of 10 G and 100 G, are parallel to the electrodes and homogeneous throughout the entire electrode gap in a direction perpendicular to the electrodes. It is found that, with a weaker magnetic field at 10 G, the plasma density is nearly doubled and the self-bias is almost unaffected. However, with a stronger magnetic field at 100 G, the plasma density is significantly increased and nearly independent of the phase angle, but at the cost of decreasing the self-bias, which results in a smaller adjustable range of ion bombardment energy. In general, we have demonstrated that an external magnetic field will expand the operational parameter spaces and thus may promote some related applications in coupled plasma sources with electrical asymmetry effects.

  14. The Weibel instability in a strongly coupled plasma

    SciTech Connect

    Mahdavi, M. Khanzadeh, H.

    2014-06-15

    In this paper, the growth rate of the Weibel instability is calculated for an energetic relativistic electron beam penetrated into a strongly coupled plasma, where the collision effects of background electron-ion scattering play an important role in equations. In order to calculate the growth rate of the Weibel instability, two different models of anisotropic distribution function are used. First, the distribution of the plasma and beam electrons considered as similar forms of bi-Maxwellian distribution. Second, the distribution functions of the plasma electrons and the beam electrons follows bi-Maxwellian and delta-like distributions, respectively. The obtained results show that the collision effect decreases the growth rate in two models. When the distribution function of electrons beam is in bi-Maxwellian form, the instability growth rate is greater than where the distribution function of beam electrons is in delta-like form, because, the anisotropic temperature for bi-Maxwellian distribution function in velocity space is greater than the delta-like distribution function.

  15. Simulation of Dual-Electrode Capacitively Coupled Plasma Discharges

    NASA Astrophysics Data System (ADS)

    Lu, Yijia; Ji, Linhong; Cheng, Jia

    2016-12-01

    Dual-electrode capacitively coupled plasma discharges are investigated here to lower the non-uniformity of plasma density. The dual-electrode structure proposed by Jung splits the electrode region and increases the flexibility of fine tuning non-uniformity. Different RF voltages, frequencies, phase-shifts and electrode areas are simulated and the influences are discussed. RF voltage and electrode area have a non-monotonic effect on non-uniformity, while frequency has a monotonic effect. Phase-shift has a cyclical influence on non-uniformity. A special combination of 224 V voltage and 11% area ratio with 10 MHz lowers the non-uniformity of the original set (200 V voltage and 0% area ratio with 10 MHz) by 46.5%. The position of the plasma density peak at the probe line has been tracked and properly tuning the phase-shift can obtain the same trace as tuning frequency or voltage. supported by National Natural Science Foundation of China (No. 51405261)

  16. Electron and ion kinetics in magnetized capacitively coupled plasma source

    SciTech Connect

    Lee, S. H.; You, S. J.; Chang, H. Y.; Lee, J. K.

    2007-05-15

    One-dimensional particle-in-cell Monte Carlo collision simulations of magnetized argon plasmas in an asymmetric capacitively coupled plasma reactor are presented. At low pressure (10 mTorr), electron kinetics are strongly affected by the magnetic field and transitions from nonlocal to local kinetic property occur with increasing magnetic field which are reflected in spatially resolved calculations of the electron-energy probability function. For high-energy electrons, the transition takes place when the energy-relaxation length is smaller than the system length. For low-energy electrons, however, the transition occurs when the electron-diffusion time scale in the energy space is shorter than the spatial-diffusion time scale in coordinate space. These observations are in agreement with experimental data and theoretical calculations deduced from the Boltzmann equation. The ion energy distribution function (IEDF) on the driven electrode changes from the ion-neutral collisional type to the ion-neutral collisionless type with increasing magnetic field strength. The maximum ion energy in the IEDF decreases and the angular spread in the ion angle distribution function slightly increases with increasing magnetic field strength. These changes are explained in terms of the ratio of the ion-transit time to rf frequency, the sheath length, and the mean potential difference between the driven electrode and the plasma. At high pressure (218 mTorr), electron-neutral collisions disrupt electron gyromotion so that the effects of the magnetic field on electron and ion kinetics are greatly reduced.

  17. Low-pressure water-cooled inductively coupled plasma torch

    DOEpatents

    Seliskar, C.J.; Warner, D.K.

    1984-02-16

    An inductively coupled plasma torch is provided which comprises an inner tube, including a sample injection port to which the sample to be tested is supplied and comprising an enlarged central portion in which the plasma flame is confined; an outer tube surrounding the inner tube and containing water therein for cooling the inner tube, the outer tube including a water inlet port to which water is supplied and a water outlet port spaced from the water inlet port and from which water is removed after flowing through the outer tube; and an rf induction coil for inducing the plasma in the gas passing into the tube through the sample injection port. The sample injection port comprises a capillary tube including a reduced diameter orifice, projecting into the lower end of the inner tube. The water inlet is located at the lower end of the outer tube and the rf heating coil is disposed around the outer tube above and adjacent to the water inlet.

  18. Low-pressure water-cooled inductively coupled plasma torch

    DOEpatents

    Seliskar, Carl J.; Warner, David K.

    1988-12-27

    An inductively coupled plasma torch is provided which comprises an inner tube, including a sample injection port to which the sample to be tested is supplied and comprising an enlarged central portion in which the plasma flame is confined; an outer tube surrounding the inner tube and containing water therein for cooling the inner tube, the outer tube including a water inlet port to which water is supplied and a water outlet port spaced from the water inlet port and from which water is removed after flowing through the outer tube; and an r.f. induction coil for inducing the plasma in the gas passing into the tube through the sample injection port. The sample injection port comprises a capillary tube including a reduced diameter orifice, projecting into the lower end of the inner tube. The water inlet is located at the lower end of the outer tube and the r.f. heating coil is disposed around the outer tube above and adjacent to the water inlet.

  19. Matrix effects in inductively coupled plasma mass spectrometry

    SciTech Connect

    Chen, Xiaoshan

    1995-07-07

    The inductively coupled plasma is an electrodeless discharge in a gas (usually Ar) at atmospheric pressure. Radio frequency energy generated by a RF power source is inductively coupled to the plasma gas through a water cooled load coil. In ICP-MS the "Fassel" TAX quartz torch commonly used in emission is mounted horizontally. The sample aerosol is introduced into the central flow, where the gas kinetic temperature is about 5000 K. The aerosol is vaporized, atomized, excited and ionized in the plasma, and the ions are subsequently extracted through two metal apertures (sampler and skimmer) into the mass spectrometer. In ICP-MS, the matrix effects, or non-spectroscopic interferences, can be defined as the type of interferences caused by dissolved concomitant salt ions in the solution. Matrix effects can be divided into two categories: (1) signal drift due to the deposition of solids on the sampling apertures; and/or (2) signal suppression or enhancement by the presence of the dissolved salts. The first category is now reasonably understood. The dissolved salts, especially refractory oxides, tend to deposit on the cool tip of the sampling cone. The clogging of the orifices reduces the ion flow into the ICP-MS, lowers the pressure in the first stage of ICP-MS, and enhances the level of metal oxide ions. Because the extent of the clogging increases with the time, the signal drifts down. Even at the very early stage of the development of ICP-MS, matrix effects had been observed. Houk et al. found out that the ICP-MS was not tolerant to solutions containing significant amounts of dissolved solids.

  20. Frequency dependent plasma characteristics in a capacitively coupled 300 mm wafer plasma processing chamber.

    SciTech Connect

    Hebner, Gregory Albert; Holland, J.P.; Paterson, A.M.; Barnat, Edward V.; Miller, Paul Albert

    2006-01-01

    Argon plasma characteristics in a dual-frequency, capacitively coupled, 300 mm-wafer plasma processing system were investigated for rf drive frequencies between 10 and 190 MHz. We report spatial and frequency dependent changes in plasma parameters such as line-integrated electron density, ion saturation current, optical emission and argon metastable density. For the conditions investigated, the line-integrated electron density was a nonlinear function of drive frequency at constant rf power. In addition, the spatial distribution of the positive ions changed from uniform to peaked in the centre as the frequency was increased. Spatially resolved optical emission increased with frequency and the relative optical emission at several spectral lines depended on frequency. Argon metastable density and spatial distribution were not a strong function of drive frequency. Metastable temperature was approximately 400 K.

  1. Coupling of an exploding plasma to a magnetized ambient plasma measured with LIF

    NASA Astrophysics Data System (ADS)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2013-10-01

    The coupling of plasma jets to ambient media near young stellar objects, Herbig-Haro objects, and supernova remnants is of considerable interest to the astrophysical community. In this work, we study the interaction of a laboratory scale jet formed by a carbon laser-produced plasma (LPP) with the ions of a magnetized argon background plasma (njet /nAr < 30 ,vjet/cs = 20 ,vjet/vA <=1) using laser-induced fluorescence (LIF). The excitation light was provided by a planar beam of a pulsed dye laser which, by tuning to the Doppler-broadened 611.5 nm absorption line, sampled the distribution function of metastable Ar-II separating the background from the components of the jet. A fast shutter (>= 3 ns) CCD camera captured the 461 nm fluorescence with 40 ns time and .6 mm2 spatial resolutions. The distribution functions obtained from the LIF diagnostic reveal significant density enhancement and a subsonic parallel drift localized at the LPP-ambient interface. Within the jet region, the background ion signal indicates the formation of a density void and suggests a lateral snow-plow effect. To our knowledge, this is the first LIF measurement of a supersonic jet coupling to an ambient plasma. Supplemental Langmuir probe measurements characterize the jet's dimensions and dependence on magnetic field strength and background ion mass up to 6 meters from the LPP source. This experiment was conducted in the Large Plasma Device at the Basic Plasma Science Facility and funded by grants from the US Department of Energy and the National Science Foundation.

  2. Research on the mechanism of multiple inductively coupled plasma source for large area processing

    NASA Astrophysics Data System (ADS)

    Lee, Jangjae; Kim, Sijun; Kim, Daewoong; Kim, Kwangki; Lee, Youngseok; You, Shinjae

    2016-09-01

    In the plasma processing, inductively coupled plasma having the high-density is often used for high productivity. In large area plasma processing, the plasma can be generated by using the multi-pole connected in parallel. However, in case of this, it is difficult for power to be transferred to plasma uniformly. To solve the problem, we studied the mechanism of inductively coupled plasma connected in parallel. By using the transformer model, the multiple ICP source is treated. We also studied about the change of the plasma parameters over the time through the power balance equation and particle balance equation. Corresponding author.

  3. Collision-less Coupling between Explosive Debris Plasmas and Magnetized Background Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Clark, S. Eric; Everson, Erik; Lee, Bo Ram; Constantin, Carmen; Niemann, Christoph

    2015-11-01

    The explosive expansion of debris plasma into magnetized background plasma characterizes a variety of astrophysical and space environments, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these and other related phenomena, collision-less electro-magnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris to the background. A unique experiment that jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA has investigated the super-Alfvénic, quasi-perpendicular expansion of a laser-produced carbon (C) debris plasma through a preformed, magnetized helium (He) background plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field probes. Collision-less coupling is directly observed via Doppler shifts in the He II 468.6 nm spectral line, which indicate that the He II ions are accelerated by the laminar electric field that develops due to the expanding C debris. By utilizing an early-time model of the C debris density and velocity, the laminar electric field is calculated and used in combination with the measured magnetic field to simulate He II ion trajectories and velocities. A synthetic Doppler-shifted wavelength spectrum of the He II 468.6 nm spectral line is generated from the simulated He II ion velocities and found to agree well with the measurements.

  4. Feedback control of plasma electron density and ion energy in an inductively coupled plasma etcher

    SciTech Connect

    Lin Chaung; Leou, K.-C.; Huang, H.-M.; Hsieh, C.-H.

    2009-01-15

    Here the authors report the development of a fuzzy logic based feedback control of the plasma electron density and ion energy for high density plasma etch process. The plasma electron density was measured using their recently developed transmission line microstrip microwave interferometer mounted on the chamber wall, and the rf voltage was measured by a commercial impedance meter connected to the wafer stage. The actuators were two 13.56 MHz rf power generators which provided the inductively coupled plasma power and bias power, respectively. The control system adopted the fuzzy logic control algorithm to reduce frequent actuator action resulting from measurement noise. The experimental results show that the first wafer effect can be eliminated using closed-loop control for both poly-Si and HfO{sub 2} etching. In particular, for the HfO2 etch, the controlled variables in this work were much more effective than the previous one where ion current was controlled, instead of the electron density. However, the pressure disturbance effect cannot be reduced using plasma electron density feedback.

  5. Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

    SciTech Connect

    Babaeva, Natalia Y.; Kushner, Mark J.

    2007-06-01

    In plasma etching equipment for microelectronics fabrication, there is an engineered gap between the edge of the wafer and wafer terminating structures, such as focus rings. The intended purpose of these structures is to make the reactant fluxes uniform to the edge of the wafer and so prevent a larger than desired edge exclusion where useful products cannot be obtained. The wafer-focus ring gap (typically<1 mm) is a mechanical requirement to allow for the motion of the wafer onto and off of the substrate. Plasma generated species can penetrate into this gap and under the beveled edge of the wafer, depositing films and possibly creating particles which produce defects. In this paper, we report on a computational investigation of capacitively coupled plasma reactors with a wafer-focus ring gap. The penetration of plasma generated species (i.e., ions and radicals) into the wafer-focus ring gap is discussed. We found that the penetration of plasma into the gap and under the wafer bevel increases as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap. Deposition of, for example, polymer by neutral species inside the gap and under the wafer is less sensitive to the size of the gap due the inability of ions, which might otherwise sputter the film, to penetrate into the gap.

  6. Unambiguous observation of F-atom core-hole localization in CF4 through body-frame photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; Lucchese, R. R.; Gaire, B.; Menssen, A.; Schöffler, M. S.; Gatton, A.; Neff, J.; Stammer, P. M.; Rist, J.; Eckart, S.; Berry, B.; Severt, T.; Sartor, J.; Moradmand, A.; Jahnke, T.; Landers, A. L.; Williams, J. B.; Ben-Itzhak, I.; Dörner, R.; Belkacem, A.; Weber, Th.

    2017-01-01

    A dramatic symmetry breaking in K -shell photoionization of the CF4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. Observing the photoejected electron in coincidence with an F+ atomic ion after Auger decay is shown to select the dissociation path where the core hole was localized almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF3+ and F+ atoms elucidates the underlying physics that derives from the Ne-like valence structure of the F(1 s-1 ) core-excited atom.

  7. Unambiguous observation of F-atom core-hole localization in CF4 through body-frame photoelectron angular distributions

    DOE PAGES

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; ...

    2017-01-17

    A dramatic symmetry breaking in K-shell photoionization of the CF4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. In observing the photoejected electron in coincidence with an F+ atomic ion after Auger decay we see how selecting the dissociation path where the core hole was localized was almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF3+ and F+ atoms elucidates the underlying physics that derives frommore » the Ne-like valence structure of the F(1s-1) core-excited atom.« less

  8. Interference effects on (e, 2e) electron momentum profiles: a comparative study for CCl4 and CF4*

    NASA Astrophysics Data System (ADS)

    Watanabe, Noboru; Katafuchi, Keisuke; Yamazaki, Masakazu; Takahashi, Masahiko

    2016-12-01

    Interference effects on electron momentum density distributions have been studied using electron momentum spectroscopy (EMS) for the three outermost orbitals of CCl4, which are constructed from the Cl 3p nonbonding atomic orbitals. The EMS experiment was conducted in the symmetric noncoplanar geometry at an incident electron energy of 2.0 keV. Interference pattern has then been obtained by dividing the experimental data by distorted-wave-Born-approximation cross section for an isolated Cl 3p atomic orbital. A comparison with the result of our earlier study on CF4 [N. Watanabe, X.-J. Chen, M. Takahashi, Phys. Rev. Lett. 108, 173201 (2012)] has demonstrated that the period of the interference pattern reflects the internuclear distance between the constituent halogen atoms. Furthermore, the present result strongly suggests that distorted-wave effects lead to partial destruction of the interference for CCl4 at large momentum.

  9. Charged Particle Dynamics in a Dual-Frequency Capacitively Coupled Fluorocarbon Plasma

    NASA Astrophysics Data System (ADS)

    Marić, Dragana; Curley, Garrett; Booth, Jean-Paul; Chabert, Pascal; Guillon, Jean

    2006-10-01

    We are studying a customized 2 + 27.12 MHz industrial etch reactor, running in Ar/O2 with c-C4F8 or CF4 gas mixtures at pressures in the region of 50 mTorr. Independent control of ion flux and ion energy is an advantage of DFC plasmas, but little experimental data exists regarding the charged particle dynamics in complex industrial gas mixtures. Negative ions could play an important role in this type of plasma. The presence of negative ions will modify the positive ion flux arriving at a surface, and may even reach the surface and participate in etching. We measure the electron density using a microwave hairpin resonator and the positive ion flux with an ion flux probe: the ratio of these two quantities varies strongly with gas chemistry and gives evidence for the presence of negative ions. We have measured high electronegativity for high c-C4F8 flowrates. We have also examined the effect of varying the 2 MHz and 27.12 MHz powers on both the electron density and positive ion flux. This allows us to estimate the effect of varying power on the negative ion density. In addition CRDS was used to measure the F^- density[1]. This optical measurement will be compared to the probe technique. [1] Booth et al, Appl. Phys. Lett. 88 (2006) 151502

  10. A study on plasma parameters in Ar/SF6 inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Oh, Seung-Ju; Lee, Hyo-Chang; Chung, Chin-Wook

    2017-01-01

    Sulfur hexafluoride (SF6) gas or Ar/SF6 mixing gas is widely used in plasma processes. However, there are a little experimental studies with various external parameters such as gas pressure and mixing ratio. In this work, a study of the plasma parameters by changing the gas mixing ratio was done in an Ar/SF6 inductively coupled plasma from the measurement of the electron energy distribution function. At a low gas pressure, as the mixing ratio of SF6 gas increased at a fixed inductively coupled plasma (ICP) power, the electron density decreased and the electron temperature increased, while they were not changed drastically. At a high gas pressure, a remarkable increase in the electron temperature was observed with the decrease in the electron density. These variations are due to the electron loss reactions such as the electron attachment. It was also found that at a fixed ICP power, the negative ion creation with the diluted SF6 gas can change the discharge mode transition from an inductive mode to a capacitive mode at the high gas pressure. The electron attachment reactions remove the low energy electrons and change the mean electron energy towards higher energies with diluting SF6 gas at high pressure. The measured results were compared with the simplified global model, and the global model is in relatively good agreement with the measured plasma parameters except for the result in the case of the large portion of SF6 gas at the high pressure and the capacitive mode, which causes strong negative ion formation by the electron attachment reactions.

  11. Quantitative aspects of inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Bulska, Ewa; Wagner, Barbara

    2016-10-01

    Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided. This article is part of the themed issue 'Quantitative mass spectrometry'.

  12. Particle dynamics in a strongly-coupled dusty plasma

    NASA Astrophysics Data System (ADS)

    Goree, J.; Pieper, J. B.

    1996-11-01

    We have used video imaging to study the dynamics of 9 μ m plastic spheres suspended in low-power Krypton discharges. The spheres, which are highly charged and levitated by the electrode sheath, form a strongly-coupled system. Using a digitized series of images, we tracked individual particles and measured collective and random particle motions.footnote J. B. Pieper and J. Goree, submitted to PRL Dust acoustic waves were excited at <= 10 Hz and their dispersion relation verified. Fitting the measured and theoretical dispersion relations also give a measurement of the particle charge and the "linearized" Debye length. The temperature of random particle motion in the horizontal plane (parallel to the electrode) was measured to be 2-10 times room temperature and about 2 times the temperature in the vertical plane. It is proposed that the particles are heated by low-frequency (kHz) electrostatic plasma fluctuations. Work supported by NSF and NASA

  13. Particle dynamics in a strongly-coupled dusty plasma

    NASA Astrophysics Data System (ADS)

    Quinn, R. A.; Goree, J.; Pieper, J. B.

    1996-10-01

    We have used video imaging to study the dynamics of 9 μ m plastic spheres in low-power Krypton discharges. The spheres, which are highly charged and levitated by the electrode sheath, form a strongly-coupled system. Using a digitized series of images, we tracked individual particles and measured collective and random particle motions.footnote Pieper and Goree, submitted to PRL Dust acoustic waves were excited at <= 10 Hz and their dispersion relation verified. The temperature of random particle motion in the horizontal plane (parallel to the electrode) was measured to be 2-10 times room temperature and about 2 times the temperature in the vertical plane. It is proposed that the particles are heated by low-frequency (kHz) electrostatic plasma fluctuations.

  14. Inductively Coupled Plasma Mass Spectrometry Uranium Error Propagation

    SciTech Connect

    Hickman, D P; Maclean, S; Shepley, D; Shaw, R K

    2001-07-01

    The Hazards Control Department at Lawrence Livermore National Laboratory (LLNL) uses Inductively Coupled Plasma Mass Spectrometer (ICP/MS) technology to analyze uranium in urine. The ICP/MS used by the Hazards Control Department is a Perkin-Elmer Elan 6000 ICP/MS. The Department of Energy Laboratory Accreditation Program requires that the total error be assessed for bioassay measurements. A previous evaluation of the errors associated with the ICP/MS measurement of uranium demonstrated a {+-} 9.6% error in the range of 0.01 to 0.02 {micro}g/l. However, the propagation of total error for concentrations above and below this level have heretofore been undetermined. This document is an evaluation of the errors associated with the current LLNL ICP/MS method for a more expanded range of uranium concentrations.

  15. The Use of Coupled Plasma Filtration Adsorption in Traumatic Rhabdomyolysis

    PubMed Central

    Renda, Silvia; Giglio, Anna Maria; Scozzafava, Anna Maria; Tiburzi, Simona Paola; Casella, Patrizia; Iannelli, Fabrizio; Verre, Mario

    2017-01-01

    Severe musculoskeletal injuries induce the release of sarcoplasmic elements such as muscle enzymes, potassium, and myoglobin in the systemic circulation. The circulating myoglobin damages the glomerulus and renal tubules. Conventional haemodialysis is not able to remove myoglobin, due to its high molecular weight (17,8 kilodaltons [kDa]). We treated four traumatic rhabdomyolysis patients with Coupled Plasma Filtration Adsorption (CPFA) in order to remove myoglobin followed by 14 hours of Continuous Veno-Venous Hemofiltration (CVVH). During the treatment, all patients showed clinical improvement with a decrease in muscular (creatine kinase [CK] and myoglobin) and renal (creatinine and potassium) damage indices. One patient, in spite of full renal recovery, died of cerebral haemorrhage on the 26th day of hospital stay. PMID:28409035

  16. Quantitative aspects of inductively coupled plasma mass spectrometry.

    PubMed

    Bulska, Ewa; Wagner, Barbara

    2016-10-28

    Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided.This article is part of the themed issue 'Quantitative mass spectrometry'.

  17. Classical strongly coupled quark-gluon plasma. VII. Energy loss

    SciTech Connect

    Cho, Sungtae; Zahed, Ismail

    2010-12-15

    We use linear response analysis and the fluctuation-dissipation theorem to derive the energy loss of a heavy quark in the SU(2) classical Coulomb plasma in terms of the l=1 monopole and nonstatic structure factor. The result is valid for all Coulomb couplings {Gamma}=V/K, the ratio of the mean potential to kinetic energy. We use the Liouville equation in the collisionless limit to assess the SU(2) nonstatic structure factor. We find the energy loss to be strongly dependent on {Gamma}. In the liquid phase with {Gamma}{approx_equal}4, the energy loss is mostly metallic and soundless with neither a Cerenkov nor a Mach cone. Our analytical results compare favorably with the SU(2) molecular dynamics simulations at large momentum and for heavy quark masses.

  18. Quantum simulations of strongly coupled quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2011-12-01

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method, which improves the corresponding classical simulations by extending them to the quantum regime. It is shown that this method is able to reproduce the lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective stringlike forces. Quantum effects turned out to be of prime importance in these simulations.

  19. Quantum simulations of strongly coupled quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Filinov, V. S.; Ivanov, Yu. B.; Bonitz, M.; Levashov, P. R.; Fortov, V. E.

    2011-09-01

    A strongly coupled quark-gluon plasma (QGP) of heavy constituent quasiparticles is studied by a path-integral Monte-Carlo method. This approach is a quantum generalization of the model developed by B.A. Gelman, E.V. Shuryak, and I. Zahed. It is shown that this method is able to reproduce the QCD lattice equation of state and also yields valuable insight into the internal structure of the QGP. The results indicate that the QGP reveals liquid-like rather than gas-like properties. At temperatures just above the critical one it was found that bound quark-antiquark states still survive. These states are bound by effective string-like forces and turn out to be colorless. At the temperature as large as twice the critical one no bound states are observed. Quantum effects turned out to be of prime importance in these simulations.

  20. Phosphorus doped graphene by inductively coupled plasma and triphenylphosphine treatments

    SciTech Connect

    Shin, Dong-Wook Kim, Tae Sung; Yoo, Ji-Beom

    2016-10-15

    Highlights: • Substitution doping is a promising method for opening the energy band gap of graphene. • Substitution doping with phosphorus in the graphene lattice has numerous advantage such as high band gap, low formation energy, and high net charge density compared to nitrogen. • V{sub dirac} of Inductively coupled plasma (ICP) and triphenylphosphine (TPP) treated graphene was −57 V, which provided clear evidence of n-type doping. • Substitutional doping of graphene with phosphorus is verified by the XPS spectra of P 2p core level and EELS mapping of phosphorus. • The chemical bonding between P and graphene is very stable for a long time in air (2 months). - Abstract: Graphene is considered a host material for various applications in next-generation electronic devices. However, despite its excellent properties, one of the most important issues to be solved as an electronic material is the creation of an energy band gap. Substitution doping is a promising method for opening the energy band gap of graphene. Herein, we demonstrate the substitutional doping of graphene with phosphorus using inductively coupled plasma (ICP) and triphenylphosphine (TPP) treatments. The electrical transfer characteristics of the phosphorus doped graphene field effect transistor (GFET) have a V{sub dirac} of ∼ − 54 V. The chemical bonding between P and C was clearly observed in XPS spectra, and uniform distribution of phosphorus within graphene domains was confirmed by EELS mapping. The capability for substitutional doping of graphene with phosphorus can significantly promote the development of graphene based electronic devices.

  1. A tightly coupled non-equilibrium model for inductively coupled radio-frequency plasmas

    SciTech Connect

    Munafò, A. Alfuhaid, S. A. Panesi, M.; Cambier, J.-L.

    2015-10-07

    The objective of the present work is the development of a tightly coupled magneto-hydrodynamic model for inductively coupled radio-frequency plasmas. Non Local Thermodynamic Equilibrium (NLTE) effects are described based on a hybrid State-to-State approach. A multi-temperature formulation is used to account for thermal non-equilibrium between translation of heavy-particles and vibration of molecules. Excited electronic states of atoms are instead treated as separate pseudo-species, allowing for non-Boltzmann distributions of their populations. Free-electrons are assumed Maxwellian at their own temperature. The governing equations for the electro-magnetic field and the gas properties (e.g., chemical composition and temperatures) are written as a coupled system of time-dependent conservation laws. Steady-state solutions are obtained by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical composition and temperature distributions along the torch radius shows that: (i) the use of the LTE assumption may lead to an inaccurate prediction of the thermo-chemical state of the gas, and (ii) non-equilibrium phenomena play a significant role close the walls, due to the combined effects of Ohmic heating and macroscopic gradients.

  2. Color quantum simulations of strongly coupled quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Filinov, Vladimir; Fortov, Vladimir; Bonitz, Mishael; Ivanov, Yurii; Levashov, Pavel

    2012-02-01

    We propose stochastic simulation of thermodynamics and kinetic properties for quark-gluon plasma (QGP) in semi-classical approximation in the wide region of temperature, density and quasi-particles masses. In grand canonical ensemble for finite and zero baryon chemical potential we use the direct quantum path integral Monte Carlo method (PIMC) developed for finite temperature within Feynman formulation of quantum mechanics to do calculations of internal energy, pressure and pair correlation functions. The QGP quasi-particles representing dressed quarks, antiquarks and gluons interact via color quantum Kelbg pseudopotential rigorously derived for Coulomb particles. This method has been successfully applied to strongly coupled electrodynamic plasmas (EMP). A strongly correlated behavior of the QGP is expected to show up in long-ranged spatial correlations of quarks and gluons which, in fact, may give rise to liquid-like and, possibly, solid-like structures. We have done already the first calculation of the QGP equation of state, spatial and color pair distribution functions, diffusion coefficients and shear viscosity.

  3. Stopping power in nonideal and strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Morawetz, K.; Röpke, G.

    1996-10-01

    The stopping power of dense nonideal plasmas is calculated in different approximations. The T-matrix approximation for binary collisions is compared with the random phase approximation for dielectric fluctuations. Within a microscopic model, the dynamical evolution of the velocity of the projectile is calculated. It reproduces well experimental values for the stopping of fast heavy ions. A comparison with molecular dynamical simulation is performed for the friction coefficient. It is found that the T matrix reproduces the simulation result with a charge dependence of ξ1.4, where ξ=ZΓ3/2. The connection to transport properties like conductivity is presented. In this way we extend former small Γ expansions to strongly coupled plasmas. Further improvements due to correlations are discussed. Both concepts, cluster decomposition and memory, are compared and it is found that they lead to the same quantum virial corrections of Beth-Uhlenbeck type in equilibrium. However, memory in the kinetic equation causes an additional renormalization of the effective energy transfer in nonequilibrium.

  4. Analysis of trimethylgallium with inductively coupled plasma spectrometry

    SciTech Connect

    Bertenyi, I.; Barnes, R.M.

    1986-07-01

    Two methods for the analysis of trimethylgallium (TMG) are described. Since TMG is pyrophoric and volatile and the nature of its impurity species is not known, separate methods were employed for volatile and nonvolatile impurities. The nonvolatile impurities (Al, Cu, Fe, Mg) were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in an aqueous solution of decomposed TMG with conventional nebulization. The volatile impurity silicon in TMG also was determined by ICP-AES but with exponential dilution. A known quantity of TMG was placed in an exponential dilution flask, and argon swept the vapor out of the flask into the plasma. Limits of detection in 1 g of TMG were 2 ..mu..g of Al, 0.6 ..mu..g of Fe, 0.6 ..mu..g of Cu, and 0.08 ..mu..g of Mg. The Si detection limit was 0.6 ..mu..g. The analysis precision for practical samples was 10-20%.

  5. Inductively Coupled Plasma Zoom-Time-of-Flight Mass Spectrometry.

    PubMed

    Dennis, Elise A; Ray, Steven J; Enke, Christie G; Hieftje, Gary M

    2016-03-01

    A zoom-time-of-flight mass spectrometer has been coupled to an inductively coupled plasma (ICP) ionization source. Zoom-time-of-flight mass spectrometry (zoom-TOFMS) combines two complementary types of velocity-based mass separation. Specifically, zoom-TOFMS alternates between conventional, constant-energy acceleration (CEA) TOFMS and energy-focused, constant-momentum acceleration (CMA) (zoom) TOFMS. The CMA mode provides a mass-resolution enhancement of 1.5-1.7× over CEA-TOFMS in the current, 35-cm ICP-zoom-TOFMS instrument geometry. The maximum resolving power (full-width at half-maximum) for the ICP-zoom-TOFMS instrument is 1200 for CEA-TOFMS and 1900 for CMA-TOFMS. The CMA mode yields detection limits of between 0.02 and 0.8 ppt, depending upon the repetition rate and integration time-compared with single ppt detection limits for CEA-TOFMS. Isotope-ratio precision is shot-noise limited at approximately 0.2% relative-standard deviation (RSD) for both CEA- and CMA-TOFMS at a 10 kHz repetition rate and an integration time of 3-5 min. When the repetition rate is increased to 43.5 kHz for CMA, the shot-noise limited, zoom-mode isotope-ratio precision is improved to 0.09% RSD for the same integration time.

  6. Effective design of multiple hollow cathode electrode to enhance the density of rf capacitively coupled plasma

    SciTech Connect

    Lee, H. S.; Lee, Y. S.; Seo, S. H.; Chang, H. Y.

    2010-08-23

    Multiple-hole electrode rf capacitively coupled plasma is experimentally studied to determine the optimum condition for high-density plasma discharge. The plasma density was measured at various pressures, hole diameters, rf currents, and gas species conditions. The bulk plasma intrusion in the hole and the ionization avalanche in the sheath region facilitated high-density plasma generation when the diameter of the hole is slightly wider than triple the sheath length. The analytic design of the efficient multihole electrode for high-density rf capacitively coupled plasma discharge will be discussed.

  7. Effective design of multiple hollow cathode electrode to enhance the density of rf capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, H. S.; Lee, Y. S.; Seo, S. H.; Chang, H. Y.

    2010-08-01

    Multiple-hole electrode rf capacitively coupled plasma is experimentally studied to determine the optimum condition for high-density plasma discharge. The plasma density was measured at various pressures, hole diameters, rf currents, and gas species conditions. The bulk plasma intrusion in the hole and the ionization avalanche in the sheath region facilitated high-density plasma generation when the diameter of the hole is slightly wider than triple the sheath length. The analytic design of the efficient multihole electrode for high-density rf capacitively coupled plasma discharge will be discussed.

  8. Heating of a dual frequency capacitively coupled plasma via the plasma series resonance

    NASA Astrophysics Data System (ADS)

    Semmler, E.; Awakowicz, P.; von Keudell, A.

    2007-11-01

    The behavior of dual frequency capacitively coupled plasma discharges (2f-CCP) is experimentally studied by Langmuir probe and rf current measurements and is compared with simulations from the literature. The driving frequency ratio, system pressure, high frequency (HF) power and low frequency (LF) power are varied in the experiments. An increase in LF power causes a moderate increase in electron density but a significant decrease in electron temperature. An increase in HF power causes a strong increase in electron density and populates the high energy part of the electron energy distribution function. These dependences can be explained on the basis of a global model. It is shown that the ratios of HF/LF power and driving frequency are the most important parameters. At integer frequency ratios a significant increase in electron density was found, which is explained by the indirect heating at the plasma series resonance. Several design guidelines are derived which address industrial applications and process stability.

  9. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    DOE PAGES

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-03-02

    We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized bymore » the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10-5 to 10-11. Free molecular heat and mass transfer theory was

  10. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    SciTech Connect

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-03-02

    We used an electrostatic size classification technique to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Moreover, we counted size-segregated particles with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10-5 to 10-11. Free molecular heat and mass transfer

  11. Aerosol detection efficiency in inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Hubbard, Joshua A.; Zigmond, Joseph A.

    2016-05-01

    An electrostatic size classification technique was used to segregate particles of known composition prior to being injected into an inductively coupled plasma mass spectrometer (ICP-MS). Size-segregated particles were counted with a condensation nuclei counter as well as sampled with an ICP-MS. By injecting particles of known size, composition, and aerosol concentration into the ICP-MS, efficiencies of the order of magnitude aerosol detection were calculated, and the particle size dependencies for volatile and refractory species were quantified. Similar to laser ablation ICP-MS, aerosol detection efficiency was defined as the rate at which atoms were detected in the ICP-MS normalized by the rate at which atoms were injected in the form of particles. This method adds valuable insight into the development of technologies like laser ablation ICP-MS where aerosol particles (of relatively unknown size and gas concentration) are generated during ablation and then transported into the plasma of an ICP-MS. In this study, we characterized aerosol detection efficiencies of volatile species gold and silver along with refractory species aluminum oxide, cerium oxide, and yttrium oxide. Aerosols were generated with electrical mobility diameters ranging from 100 to 1000 nm. In general, it was observed that refractory species had lower aerosol detection efficiencies than volatile species, and there were strong dependencies on particle size and plasma torch residence time. Volatile species showed a distinct transition point at which aerosol detection efficiency began decreasing with increasing particle size. This critical diameter indicated the largest particle size for which complete particle detection should be expected and agreed with theories published in other works. Aerosol detection efficiencies also displayed power law dependencies on particle size. Aerosol detection efficiencies ranged from 10- 5 to 10- 11. Free molecular heat and mass transfer theory was applied, but

  12. Determination of silver in nano-plastic food packaging by microwave digestion coupled with inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry.

    PubMed

    Lin, Q-B; Li, B; Song, H; Wu, H-J

    2011-08-01

    The detection of silver in nano-plastic food packaging by microwave digestion coupled with either inductively coupled plasma atomic emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) was investigated. Microwave digestion was optimised by trialling different acid mixtures. Both ICP-AES and ICP-MS showed good reproducibility, repeatability and recovery. For ICP-AES the limit of detection of the method (LODm) was 25.0 µg g(-1), the limit of detection of the instrument (LODi) was 30.0 ng ml(-1), the linear range was 0.10-10.0 µg ml(-1). The average recoveries for blank samples spiked with silver at 100, 250 and 500 µg g(-1) ranged from 82.53% to 87.60%, and the relative standard deviations (RSDs) were from 1.79% to 8.30%. For ICP-MS analysis the LODm was 0.75 µg g(-1), the LODi was 0.04 ng ml(-1), the linear range was 0.20-500.0 ng ml(-1), the RSDs were 2.26-4.79%, and the recoveries were 78.09-92.72% (spiked concentrations of 2.5, 5.0 and 10.0 µg g(-1)). These results indicate that the proposed method could be employed to analyse silver in nano-plastic food packaging.

  13. Relationship between the discharge mode and the spatial oxygen plasma distribution in a large size ferrite inductively coupled plasmas

    SciTech Connect

    Kim, Hyun Jun; Hwang, Hye Ju; Cho, Jeong Hee; Chae, Hee Sun; Kim, Dong Hwan; Chung, Chin-Wook

    2015-04-15

    The electrical characteristics and the spatial distribution of oxygen plasma according to the number of turns in ferrite inductively coupled plasmas (ferrite ICPs) are investigated. Through a new ICP model, which includes the capacitive coupling and the power loss of the ferrite material with the conventional ICP model, the variation of the oxygen discharge characteristics depending on the number of turns is simply understood by the electrical measurement, such as the antenna voltages and the currents. As the number of the turns increases, the capacitive coupling dominantly affects the spatial plasma distribution. This capacitive coupling results in a center focused density profile along the radial direction. In spite of the same discharge conditions (discharge chamber, neutral gas, and pressure), the spatial plasma distribution over 450 mm has drastic changes by increasing number of the turns. In addition, the effect of the negative species to the density profile is compared with the argon discharge characteristics at the same discharge configuration.

  14. Optical Diagnostics of the Plasma and Surface during Inductively Coupled Plasma Etching

    NASA Astrophysics Data System (ADS)

    Herman, Irving P.

    1999-10-01

    The use of optical diagnostics to analyze the etching of Si, Ge, and InP by chlorine in an inductively coupled plasma (ICP) is investigated. Optical probes, along with other conventional plasma diagnostics, are used to characterize the process through measurements of the constituents of the plasma and the surface composition to obtain a more complete picture of the etching process. Neutral Cl2 and Cl densities are determined by optical emission actinometry by following optical emission from Cl_2. The absolute densities of Cl_2^+ and Cl^+ are determined by laser- induced fluorescence (LIF) of Cl_2^+ and Langmuir probe measurements of the total positive ion density. The surface is probed by using laser-induced thermal desorption with an XeCl laser (308 nm) to desorb the steady-state adlayer and optical methods to detect these desorbed species. The development of a new method to detect optically these laser desorbed (LD) species is detailed, that of examining transient changes in the plasma-induced emission (PIE). This LD-PIE method is more universal than the previously reported detection by LIF (LD-LIF), but requires more calibration due to varying electron density and temperature with varying plasma conditions. This is detailed for Si etching, for which LD-PIE and LD-LIF results are compared. The calibration methods are seen to be valid when the surface is analyzed as the rf power supplied to the reactor is varied. The electron density - needed for LD-PIE calibration - is measured by microwave interferometry. An improved understanding of the etching mechanism is obtained by combining the results of each of these measurements. This work was supported by NSF Grant No. DMR-98-15846. note

  15. Dual Comb Raman Spectroscopy on Cesium Hyperfine Transitions-Toward a Stimulate Raman Spectrum on CF4 Molecule

    NASA Astrophysics Data System (ADS)

    Liu, Tze-Wei; Hsu, Yen-Chu; Cheng, Wang-Yau

    2015-06-01

    Raman spectroscopy is an important spectroscopic technique used in chemistry to provide a fingerprint by which molecules can be identified. It helps us to observe vibration- rotation, and other low-frequency modes in a system. Dual comb Raman spectroscopy allows measuring a wide bandwidth with high resolution in microseconds. The stimulate Raman spectroscopy had been performed in early days where the nonlinear conversion efficiency depended on laser peak power. Hence we propose an approach for rapidly resolving the Raman spectroscopy of CF4 molecule by two Ti:sapphire comb lasers. Our progress on this proposal will be presented in the conference. First, we have realized a compact dual Ti:sapphire comb laser system where the dual Ti:sapphire laser system possesses the specification of 1 GHz repetition rate. In our dual comb system, 1 GHz repetition rate, 100 kHz Δfrep and 2.4 THz optical filter are chosen according to the demands of our future works on spectroscopy. Therefore, the maximum mode number within free spectral range is 5*103, and the widest range of dual-comb based spectra in that each spectrum could be uniquely identified is 5 THz. The actual bandwidth is determined by the employed optical filter and is set to be 2.4 THz here, so that the corresponding data acquisition time is 10 μs. Secondly, since the identification of the tremendous spectral lines of CF4 molecule relies on a stable reference and a reliable data-retrieving system, we propose a first-step experiment on atomic system where the direct 6S-8S 822-nm two-photon absorption and 8S-6P3/2 (794 nm) enhanced stimulate Raman would be realized directly by using Ti:sapphire laser. We have successfully performed direct comb laser two-photon spectroscopy for both with and without middle-level enhanced. For the level enhanced two-photon spectrum, our experimental setup achieves Doppler-free spectrum and a record narrow linewidth (1 MHz). T.-W. Liu, C.-M. Wu, Y.-C. Hsu and W.-Y. Cheng, Appl. Phys. B

  16. Numerical investigation of ion-energy-distribution functions in single and dual frequency capacitively coupled plasma reactors.

    PubMed

    Georgieva, V; Bogaerts, A; Gijbels, R

    2004-02-01

    Ion-energy-distribution functions (IEDFs) are numerically investigated in capacitively coupled (cc) radio frequency (rf) Ar/CF(4)/N(2) discharges by a one-dimensional particle-in-cell/Monte Carlo model. The simulation considers electron-neutral collisions, various kinds of collisions of ions (Ar+, CF+3, N+2, F-, and CF-3) with neutral, positive-negative ion, and electron-ion recombination. The influence of pressure, applied voltage amplitude, and applied frequency on the Ar+, CF+3, and N+2 IEDFs is presented. The dependence on the frequency regime is investigated by simulations of the Ar/CF(4)/N(2) mixture in single (13.56 MHz) and dual frequency (2+27 MHz or 1+27 MHz) cc reactors. A comparison of the simulation results with analytical calculations in a collisionless rf sheath is discussed. The results show that the IEDFs shift toward the low energies with increasing pressure or decreasing applied voltage amplitude. The Ar+ and N+2 IEDFs exhibit secondary maxima due to the charge transfer collisions. The CF+3 IEDF has a peak at high energies in consistency with the average sheath potential drop. The IEDFs in the dual frequency regime are broad and bimodal.

  17. The role of the relative voltage and phase for frequency coupling in a dual-frequency capacitively coupled plasma

    SciTech Connect

    O'Connell, D.; Gans, T.; Semmler, E.; Awakowicz, P.

    2008-08-25

    Frequency coupling in multifrequency discharges is a complex nonlinear interaction of the different frequency components. An alpha-mode low pressure rf capacitively coupled plasma operated simultaneously with two frequencies is investigated and the coupling of the two frequencies is observed to greatly influence the excitation and ionization within the discharge. Through this, plasma production and sustainment are dictated by the corresponding electron dynamics and can be manipulated through the dual-frequency sheath. These mechanisms are influenced by the relative voltage and also the relative phase of the two frequencies.

  18. Finite-Difference Solution for Laminar or Turbulent Boundary Layer Flow over Axisymmetric Bodies with Ideal Gas, CF4, or Equilibrium Air Chemistry

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris, II; Millman, Daniel R.; Greendyke, Robert B.

    1992-01-01

    A computer code was developed that uses an implicit finite-difference technique to solve nonsimilar, axisymmetric boundary layer equations for both laminar and turbulent flow. The code can treat ideal gases, air in chemical equilibrium, and carbon tetrafluoride (CF4), which is a useful gas for hypersonic blunt-body simulations. This is the only known boundary layer code that can treat CF4. Comparisons with experimental data have demonstrated that accurate solutions are obtained. The method should prove useful as an analysis tool for comparing calculations with wind tunnel experiments and for making calculations about flight vehicles where equilibrium air chemistry assumptions are valid.

  19. Kolmogorov flow in two dimensional strongly coupled dusty plasma

    SciTech Connect

    Gupta, Akanksha; Ganesh, R. Joy, Ashwin

    2014-07-15

    Undriven, incompressible Kolmogorov flow in two dimensional doubly periodic strongly coupled dusty plasma is modelled using generalised hydrodynamics, both in linear and nonlinear regime. A complete stability diagram is obtained for low Reynolds numbers R and for a range of viscoelastic relaxation time τ{sub m} [0 < τ{sub m} < 10]. For the system size considered, using a linear stability analysis, similar to Navier Stokes fluid (τ{sub m} = 0), it is found that for Reynolds number beyond a critical R, say R{sub c}, the Kolmogorov flow becomes unstable. Importantly, it is found that R{sub c} is strongly reduced for increasing values of τ{sub m}. A critical τ{sub m}{sup c} is found above which Kolmogorov flow is unconditionally unstable and becomes independent of Reynolds number. For R < R{sub c}, the neutral stability regime found in Navier Stokes fluid (τ{sub m} = 0) is now found to be a damped regime in viscoelastic fluids, thus changing the fundamental nature of transition of Kolmogorov flow as function of Reynolds number R. A new parallelized nonlinear pseudo spectral code has been developed and is benchmarked against eigen values for Kolmogorov flow obtained from linear analysis. Nonlinear states obtained from the pseudo spectral code exhibit cyclicity and pattern formation in vorticity and viscoelastic oscillations in energy.

  20. Gold fingerprinting by laser ablation inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Watling, R. John; Herbert, Hugh K.; Delev, Dianne; Abell, Ian D.

    1994-02-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to the characterization of the trace element composition "fingerprint" of selected gold samples from Western Australia and South Africa. By comparison of the elemental associations it is possible to relate gold to a specific mineralizing event, mine or bullion sample. This methodology facilitates identification of the provenance of stolen gold or gold used in salting activities. In this latter case, it is common for gold from a number of sources to be used in the salting process. Consequently, gold in the prospect being salted will not come from a single source and identification of multiple sources for this gold will establish that salting has occurred. Preliminary results also indicate that specific elemental associations could be used to identify the country of origin of gold. The technique has already been applied in 17 cases involving gold theft in Western Australia, where it is estimated that up to 2% of gold production is "relocated" each year as a result of criminal activities.

  1. Strongly coupled quark-gluon plasma in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Shuryak, Edward

    2017-07-01

    A decade ago, a brief summary of the field of the relativistic heavy ion physics could be formulated as the discovery of strongly coupled quark-gluon plasma, sQGP for short, a near-perfect fluid with surprisingly large entropy-density-to-viscosity ratio. Since 2010, the LHC heavy ion program added excellent new data and discoveries. Significant theoretical efforts have been made to understand these phenomena. Now there is a need to consolidate what we have learned and formulate a list of issues to be studied next. Studies of angular correlations of two and more secondaries reveal higher harmonics of flow, identified as the sound waves induced by the initial state perturbations. As in cosmology, detailed measurements and calculations of these correlations helped to make our knowledge of the explosion much more quantitative. In particular, their damping had quantified the viscosity. Other kinetic coefficients—the heavy-quark diffusion constants and the jet quenching parameters—also show enhancements near the critical point T ≈Tc. Since densities of QGP quarks and gluons strongly decrease at this point, these facts indicate large role of nonperturbative mechanisms, e.g., scattering on monopoles. New studies of the p p and p A collisions at high multiplicities reveal collective explosions similar to those in heavy ion A A collisions. These "smallest drops of the sQGP" revived debates about the initial out-of-equilibrium stage of the collisions and mechanisms of subsequent equilibration.

  2. Effect of random charge fluctuation on strongly coupled dusty Plasma

    SciTech Connect

    Issaad, M.; Rouiguia, L.; Djebli, M.

    2008-09-07

    Modeling the interaction between particles is an open issue in dusty plasma. We dealt with strongly coupled dust particles in two dimensional confined system. For small number of clusters, we investigate the effect of random charge fluctuation on background configuration. The study is conducted for a short rang as well as a long rang potential interaction. Numerical simulation is performed using Monte-Carlo simulation in the presence of parabolic confinement and at low temperature. We have studied the background configurations for a dust particles with constant charge and in the presence of random charge fluctuation due to the discrete nature of charge carriers. The latter is studied for a positively charged dust when the dominant charging process is due to photo-emission from the dust surface. It is found, for small classical cluster consisting of small number of particles, short rang potential gives the same result as long rang one. It is also found that the random charge fluctuation affect the background configurations.

  3. Environmental analysis by inductively coupled plasma mass spectrometry.

    PubMed

    Beauchemin, Diane

    2010-01-01

    This article reviews the numerous ways in which inductively coupled plasma mass spectrometry has been used for the analysis of environmental samples since it was commercially introduced in 1983. Its multielemental isotopic capability, high sensitivity and wide linear dynamic range makes it ideally suited for environmental analysis. Provided that some care is taken during sample preparation and that appropriate calibration strategies are used to circumvent non-spectroscopic interferences, the technique is readily applicable to the analysis of a wide variety of environmental samples (natural waters, soils, rocks, sediments, vegetation, etc.), using quadrupole, time-of-flight or double-focusing sector-field mass spectrometers. In cases where spectroscopic interferences arising from the sample matrix cannot be resolved, then separation methods can be implemented either on- or off-line, which can simultaneously allow analyte preconcentration, thus further decreasing the already low detection limits that are achievable. In most cases, the blank, prepared by following the same steps as for the sample but without the sample, limits the ultimate detection limits that can be reached.

  4. Uranium quantification in semen by inductively coupled plasma mass spectrometry

    USGS Publications Warehouse

    Todorov, Todor; Ejnik, John W.; Guandalini, Gustavo S.; Xu, Hanna; Hoover, Dennis; Anderson, Larry W.; Squibb, Katherine; McDiarmid, Melissa A.; Centeno, Jose A.

    2013-01-01

    In this study we report uranium analysis for human semen samples. Uranium quantification was performed by inductively coupled plasma mass spectrometry. No additives, such as chymotrypsin or bovine serum albumin, were used for semen liquefaction, as they showed significant uranium content. For method validation we spiked 2 g aliquots of pooled control semen at three different levels of uranium: low at 5 pg/g, medium at 50 pg/g, and high at 1000 pg/g. The detection limit was determined to be 0.8 pg/g uranium in human semen. The data reproduced within 1.4–7% RSD and spike recoveries were 97–100%. The uranium level of the unspiked, pooled control semen was 2.9 pg/g of semen (n = 10). In addition six semen samples from a cohort of Veterans exposed to depleted uranium (DU) in the 1991 Gulf War were analyzed with no knowledge of their exposure history. Uranium levels in the Veterans’ semen samples ranged from undetectable (<0.8 pg/g) to 3350 pg/g. This wide concentration range for uranium in semen is consistent with known differences in current DU body burdens in these individuals, some of whom have retained embedded DU fragments.

  5. Uranium quantification in semen by inductively coupled plasma mass spectrometry.

    PubMed

    Todorov, Todor I; Ejnik, John W; Guandalini, Gustavo; Xu, Hanna; Hoover, Dennis; Anderson, Larry; Squibb, Katherine; McDiarmid, Melissa A; Centeno, Jose A

    2013-01-01

    In this study we report uranium analysis for human semen samples. Uranium quantification was performed by inductively coupled plasma mass spectrometry. No additives, such as chymotrypsin or bovine serum albumin, were used for semen liquefaction, as they showed significant uranium content. For method validation we spiked 2g aliquots of pooled control semen at three different levels of uranium: low at 5 pg/g, medium at 50 pg/g, and high at 1000 pg/g. The detection limit was determined to be 0.8 pg/g uranium in human semen. The data reproduced within 1.4-7% RSD and spike recoveries were 97-100%. The uranium level of the unspiked, pooled control semen was 2.9 pg/g of semen (n=10). In addition six semen samples from a cohort of Veterans exposed to depleted uranium (DU) in the 1991 Gulf War were analyzed with no knowledge of their exposure history. Uranium levels in the Veterans' semen samples ranged from undetectable (<0.8 pg/g) to 3350 pg/g. This wide concentration range for uranium in semen is consistent with known differences in current DU body burdens in these individuals, some of whom have retained embedded DU fragments. Published by Elsevier GmbH.

  6. Transport and mixing in strongly coupled dusty plasma medium

    NASA Astrophysics Data System (ADS)

    Dharodi, Vikram; Das, Amita; Patel, Bhavesh

    2016-10-01

    The generalized hydrodynamic (GHD) fluid model has been employed to study the transport and mixing properties of Dusty plasma medium in strong coupling limit. The response of lighter electron and ion species to the dust motion is taken to be instantaneous i.e. inertia-less. Thus the electron and ion density are presumed to follow the Boltzman relation. In the incompressible limit (i-GHD) the model supports Transverse Shear wave in contrast to the Hydrodynamic fluids. It has been shown that the presence of these waves leads to a better mixing of fluid in this case. Several cases of flow configuration have been considered for the study. The transport and mixing attributes have been quantified by studying the dynamical evolution of tracer particles in the system. The diffusion and clustering of these test particles are directly linked to the mixing characteristic of a medium. The displacement of these particles provides for a quantitative estimate of the diffusion coefficient of the medium. It is shown that these test particles often organize themselves in spatially inhomogeneous pattern leading to the phenomena of clustering.

  7. Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams

    NASA Astrophysics Data System (ADS)

    Nichiporov, D.; Coutinho, L.; Klyachko, A. V.

    2016-04-01

    Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector’s performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115-205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, and especially in small-field applications.

  8. Enhancements in dissociative electron attachment to CF4, chlorofluorocarbons and hydrochlorofluorocarbons adsorbed on H2O ice.

    PubMed

    Lu, Q-B; Sanche, L

    2004-02-01

    We report that the absolute cross sections for dissociative attachment of approximately 0 eV electrons to chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are strongly enhanced by the presence of H2O ice. The absolute cross sections for CFCl3, CHF2Cl, and CH3CF2Cl on water ice are measured to be approximately 8.9 x 10(-14), approximately 5.1 x 10(-15), and approximately 4.9 x 10(-15) cm2 at approximately 0 eV, respectively. The former value is about 1 order of magnitude higher than that in the gas phase, while the latter two are 3-4 orders higher. In contrast, the resonances at electron energies > or = 2.0 eV are strongly suppressed either for CFCs and HCFCs or for CF4 adsorbed on H2O ice. The cross-section enhancement is interpreted to be due to electron transfer from precursor states of the solvated electron in ice to an unfilled molecular orbital of CFCs or HCFCs followed by its dissociation. This study indicates that electron-induced dissociation is a significant process leading to CFC and HCFC fragmentation on ice surfaces. Copyright 2004 American Institute of Physics

  9. Ultrafast dynamics in C 1s core-excited CF4 revealed by two-dimensional resonant Auger spectroscopy.

    PubMed

    Piancastelli, M N; Guillemin, R; Simon, M; Iwayama, H; Shigemasa, E

    2013-06-21

    Following core excitation in an isolated molecule, ultrafast dissociation of one particular chemical bond can occur, where "ultrafast" is defined as taking place during the lifetime of the core hole, of the order of few femtoseconds. The signature of such phenomenon can be observed in resonant Auger spectra following core excitation. We present here an investigation of ultrafast dissociation following C 1s-to-σ* core excitation in CF4, with high-resolution resonant Auger spectroscopy. We are able to characterize final states of both the molecular ion and the CF3 (+) fragment. We use two-dimensional (2D) maps to record resonant Auger spectra across the resonance as a function of photon energy and to characterize ultrafast dynamics. This method provides immediate visual evidence of one of the important characteristics of the study of spectral features related to molecular versus fragment ionic final states, and namely their dispersion law. In the 2D maps we are also able to identify the dissociation limit for one of the molecular final states.

  10. Characterization of a GEM-based scintillation detector with He-CF4 gas mixture in clinical proton beams.

    PubMed

    Nichiporov, D; Coutinho, L; Klyachko, A V

    2016-04-21

    Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector's performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115-205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, and especially in small-field applications.

  11. Molecular Frame Photoelectron Angular Distributions for Core Ionization of CF4 and C2H2F2

    NASA Astrophysics Data System (ADS)

    Trevisan, C. S.; Williams, J. B.; Menssen, A. J.; Rescigno, T. N.; Dorner, R.; McCurdy, C. W.

    2015-05-01

    We present experimental and theoretical results for the angular dependence of electrons ejected from the core orbitals of tetrafluoromethane (CF4) which display a tendency to avoid molecular bonds if averaged over directions of polarization of the incident X-ray beam, in contrast to earlier cases (CH4, H2O and NH3) studied by the same methods. To investigate whether the imaging effect can be used to detect the creation of core holes by photoionization from one of two atoms of the same type in a molecule, we computed and measured MFPADs of difluoroethylene (C2H2F2). Good agreement with the experimentally measured angular distributions show that the MFPADs contain the clear signature of the core-hole origin of the photoelectron, and validate the use of computed MFPADs as promising tools for the interpretation of such experiments. Our measurements employ the COLTRIMS method and the calculations were performed with the Complex Kohn Variational method. Work supported in part by the USDOE, Office of Science, Office of WDTS under the Visiting Faculty Program.

  12. Local cooling, plasma reheating and thermal pinching induced by single aerosol droplets injected into an inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Chan, George C.-Y.; Hieftje, Gary M.

    2016-07-01

    The injection of a single micrometer-sized droplet into an analytical inductively coupled plasma (ICP) perturbs the plasma and involves three sequential effects: local cooling, thermal pinching and plasma reheating. Time-resolved two-dimensional monochromatic imaging of the load-coil region of an ICP was used to monitor this sequence of plasma perturbations. When a microdroplet enters the plasma, it acts as a local heat sink and cools the nearby plasma region. The cooling effect is considered local, although the cooling volume can be large and extends 6 mm from the physical location of the vaporizing droplet. The liberated hydrogen, from decomposition of water, causes a thermal pinch effect by increasing the thermal conductivity of the bulk plasma and accelerating heat loss at the plasma periphery. As a response to the heat loss, the plasma shrinks in size, which increases its power density. Plasma shrinkage starts around the same time when the microdroplet enters the plasma and lasts at least 2 ms after the droplet leaves the load-coil region. Once the vaporizing droplet passes through a particular plasma volume, that volume is reheated to an even higher temperature than under steady-state conditions. Because of the opposing effects of plasma cooling and reheating, the plasma conditions are different upstream (downward) and downstream (upward) from a vaporizing droplet - cooling dominates the downstream region whereas reheating controls in the upstream domain. The boundary between the local cooling and reheating zones is sharp and is only ~ 1 mm thick. The reheating effect persists a relatively long time in the plasma, at least up to 4 ms after the droplet moves out of the load-coil region. The restoration of plasma equilibrium after the perturbation induced by microdroplet injection is slow. Microdroplet injection also induces a momentary change in plasma impedance, and the impedance change was found to correlate qualitatively with the different stages of plasma

  13. Plasma-based localized defect for switchable coupling applications

    SciTech Connect

    Varault, Stefan; Gabard, Benjamin; Sokoloff, Jerome; Bolioli, Sylvain

    2011-03-28

    We report in this paper experimental measurements in order to validate the concept of switchable electromagnetic band gap filters based on plasma capillaries in the microwave regime. The plasma tube is embedded inside the structure to create a bistable (plasma on or off) punctual defect. We first investigate two kinds of discharge tubes: Ar-Hg and pure Ne, which we then use to experimentally achieve plasma-based reconfigurable applications, namely, a two-port coupler and a two-port demultiplexer.

  14. 3-Dimensional Modeling of Capacitively and Inductively Coupled Plasma Etching Systems

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid

    2008-10-01

    Low temperature plasmas are widely used for thin film etching during micro and nano-electronic device fabrication. Fluid and hybrid plasma models were developed 15-20 years ago to understand the fundamentals of these plasmas and plasma etching. These models have significantly evolved since then, and are now a major tool used for new plasma hardware design and problem resolution. Plasma etching is a complex physical phenomenon, where inter-coupled plasma, electromagnetic, fluid dynamics, and thermal effects all have a major influence. The next frontier in the evolution of fluid-based plasma models is where these models are able to self-consistently treat the inter-coupling of plasma physics with fluid dynamics, electromagnetics, heat transfer and magnetostatics. We describe one such model in this paper and illustrate its use in solving engineering problems of interest for next generation plasma etcher design. Our 3-dimensional plasma model includes the full set of Maxwell equations, transport equations for all charged and neutral species in the plasma, the Navier-Stokes equation for fluid flow, and Kirchhoff's equations for the lumped external circuit. This model also includes Monte Carlo based kinetic models for secondary electrons and stochastic heating, and can take account of plasma chemistry. This modeling formalism allows us to self-consistently treat the dynamics in commercial inductively and capacitively coupled plasma etching reactors with realistic plasma chemistries, magnetic fields, and reactor geometries. We are also able to investigate the influence of the distributed electromagnetic circuit at very high frequencies (VHF) on the plasma dynamics. The model is used to assess the impact of azimuthal asymmetries in plasma reactor design (e.g., off-center pump, 3D magnetic field, slit valve, flow restrictor) on plasma characteristics at frequencies from 2 -- 180 MHz. With Jason Kenney, Ankur Agarwal, Ajit Balakrishna, Kallol Bera, and Ken Collins.

  15. Experimental Measurement of Self-Diffusion in a Strongly Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Strickler, T. S.; Langin, T. K.; McQuillen, P.; Daligault, J.; Killian, T. C.

    2016-04-01

    We present a study of the collisional relaxation of ion velocities in a strongly coupled, ultracold neutral plasma on short time scales compared to the inverse collision rate. The measured average velocity of a tagged population of ions is shown to be equivalent to the ion-velocity autocorrelation function. We thus gain access to fundamental aspects of the single-particle dynamics in strongly coupled plasmas and to the ion self-diffusion constant under conditions where experimental measurements have been lacking. Nonexponential decay towards equilibrium of the average velocity heralds non-Markovian dynamics that are not predicted by traditional descriptions of weakly coupled plasmas. This demonstrates the utility of ultracold neutral plasmas for studying the effects of strong coupling on collisional processes, which is of interest for dense laboratory and astrophysical plasmas.

  16. Experimental measurement of self-diffusion in a strongly coupled plasma

    DOE PAGES

    Strickler, Trevor S.; Langin, Thomas K.; McQuillen, Paul; ...

    2016-05-17

    Here, we present a study of the collisional relaxation of ion velocities in a strongly coupled, ultracold neutral plasma on short time scales compared to the inverse collision rate. The measured average velocity of a tagged population of ions is shown to be equivalent to the ion-velocity autocorrelation function. We thus gain access to fundamental aspects of the single-particle dynamics in strongly coupled plasmas and to the ion self-diffusion constant under conditions where experimental measurements have been lacking. Nonexponential decay towards equilibrium of the average velocity heralds non-Markovian dynamics that are not predicted by traditional descriptions of weakly coupled plasmas.more » This demonstrates the utility of ultracold neutral plasmas for studying the effects of strong coupling on collisional processes, which is of interest for dense laboratory and astrophysical plasmas.« less

  17. Determination of the spontaneous raman linewidth of CF 4 by measurements of stimulated raman scattering in both transient and steady states

    NASA Astrophysics Data System (ADS)

    Pochon, E.

    1981-02-01

    The spontaneous Raman linewith Δ v of the v1 mode of gaseous CF 4 is determined from 30 to 360 amagat by comparison of stimulated Raman scattering threshold intensity measurements performed with picosecond and nanosecond laser excitation. At high densities Δ v = 0.20 cm -1 is constant. A possible explanation of this effect is given in terms of collisional narrowing

  18. Investigation of Plasma Uniformity in Pulsed 100 MHz Narrow Gap-Capacitively Coupled Argon Plasma

    NASA Astrophysics Data System (ADS)

    Jang, Yunchang; Choi, Myungsun; Rho, Hyun-Joon; Huh, Sung-Ryul; Yoon, Sung-Young; Ryu, Sangwon; Kim, Gon-Ho

    2015-09-01

    Capacitively coupled plasmas (CCPs) for industrial applications have a narrow gap between two electrodes and a large exhaust region between electrodes and lateral walls. In this study, uniformity of electron density (ne) distribution was investigated in a 300 mm Φ CCP with outer-electrode space 4 times larger than inter-electrode space. The 100 MHz RF power was applied to top electrode at a pulse repetition rate of 5 kHz. Experiments reveals that the non-uniformity of the ne decreases from 0.60 in the active-glow period to 0.39 in after-glow period. In order to account for this phenomenon in the after-glow, the effective diffusion length representing the ratio of plasma generation volume to effective loss area is introduced. When RF power is turned off, the ne of each space starts to decrease with the specific loss rate determined by each leff. The calculated leff of the outer-electrode space is about 3.7 times longer than that in the outer-electrode space. This implies that ne of the outer-electrode space decay more slowly, leading to improve the uniformity. The details on experimental results and analysis will be presented and discussed. This research was supported by BK21 Research Division of Seoul National University for Energy Resources, Ministry of Trade, Industry and Energy Republic of Korea and Consortium of Semiconductor Advanced Research.

  19. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  20. A Self-Consistent Plasma-Sheath Model for the Inductively Coupled Plasma Reactor

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindam, T. R.; Meyyappan, M.

    2000-01-01

    Accurate determination of ion flux on a wafer requires a self-consistent, multidimensional modeling of plasma reactor that adequately resolves the sheath region adjoining the wafer. This level of modeling is difficult to achieve since non-collisional sheath lengths are usually 3-4 orders of magnitude smaller than the reactor scale. Also, the drift-diffusion equations used for ion transport becomes invalid in the sheath since the ion frictional force is no longer in equilibrium with drift and diffusion forces. The alternative is to use a full momentum equation for each ionic species. In this work we will present results from a self-consistent reactor scale-sheath scale model for 2D inductively coupled plasmas. The goal of this study is to improve the modeling capabilities and assess the importance of additional physics in determining important reactor performance features, such as the ion flux uniformity, coil frequency and configuration effects, etc. Effect of numerical dissipation on the solution quality will also be discussed.

  1. Reduction of the electrostatic coupling in a large-area internal inductively coupled plasma source using a multicusp magnetic field

    NASA Astrophysics Data System (ADS)

    Lee, Y. J.; Kim, K. N.; Yeom, G. Y.; Lieberman, M. A.

    2004-09-01

    A large area (1020mm×830mm) inductively coupled plasma (ICP) source has been developed using an internal-type linear antenna with permanent magnets forming a multicusp magnetic field. The large rf antenna voltages, which cause the electrostatic coupling between the antenna and the plasma in a large area internal-type linear-antenna ICP source, were decreased significantly by applying the magnetic field near and parallel to the antenna. Through the application of the magnetic field, an approximately 20% higher plasma density, with a value of close to 1.0×1011cm-3 at a rf power of 2000W, and about three times higher photoresist etch rates were observed, while maintaining the plasma nonuniformity at less than 9%.

  2. FY05 LDRD Final Report Coupled Turbulenc/Transport Model for Edge-Plasmas

    SciTech Connect

    Rognlien, T; Cohen, R; LoDestro, L; Palasek, R; Umansky, M; Xu, X

    2006-02-09

    An edge-plasma simulation for tokamak fusion devices is developed that couples 3D turbulence and 2D transport, including detailed sources and sinks, to determine self-consistent steady-state plasma profiles. Relaxed iterative coupling is shown to be effective when edge turbulence is partially suppressed, for example, by shear E x B shear flow as occurs during the favorable H-mode region. Unsuppressed turbulence is found to lead to large, intermittent edge transport events where the coupling procedure can lead to substantial inaccuracies in describing the true time-averaged plasma behavior.

  3. Nonlinear frequency coupling in dual radio-frequency driven atmospheric pressure plasmas

    SciTech Connect

    Waskoenig, J.; Gans, T.

    2010-05-03

    Plasma ionization, and associated mode transitions, in dual radio-frequency driven atmospheric pressure plasmas are governed through nonlinear frequency coupling in the dynamics of the plasma boundary sheath. Ionization in low-power mode is determined by the nonlinear coupling of electron heating and the momentary local plasma density. Ionization in high-power mode is driven by electron avalanches during phases of transient high electric fields within the boundary sheath. The transition between these distinctly different modes is controlled by the total voltage of both frequency components.

  4. Collisionless bounce resonance heating in dual-frequency capacitively coupled plasmas.

    PubMed

    Liu, Yong-Xin; Zhang, Quan-Zhi; Jiang, Wei; Hou, Lu-Jing; Jiang, Xiang-Zhan; Lu, Wen-Qi; Wang, You-Nian

    2011-07-29

    We present the experimental evidence of the collisionless electron bounce resonance heating (BRH) in low-pressure dual-frequency capacitively coupled plasmas. In capacitively coupled plasmas at low pressures when the discharge frequency and gap satisfy a certain resonant condition, the high energy beamlike electrons can be generated by fast sheath expansion, and heated by the two sheaths coherently, thus the BRH occurs. By using a combined measurement of a floating double probe and optical emission spectroscopy, we demonstrate the effect of BRH on plasma properties, such as plasma density and light emission, especially in dual-frequency discharges.

  5. Improved nanodiamond seeding on chromium by surface plasma pretreatment

    NASA Astrophysics Data System (ADS)

    Degutis, G.; Pobedinskas, P.; Boyen, H.-G.; Dexters, W.; Janssen, W.; Drijkoningen, S.; Hardy, A.; Haenen, K.; Van Bael, M. K.

    2015-11-01

    Surface pretreatment by gas discharge plasmas of N2, O2 and CF4 is studied for enhanced diamond nucleation on Cr surfaces. The seeding density following the interaction of water-dispersed nanodiamonds (NDs) and the Cr surface is enhanced due to chemical modification of a surface. The surface that is untreated or pretreated with N2 plasma possesses a suppressed electrostatic attraction of NDs, while the pretreatment with O2 or CF4 plasmas render a strong electrostatic attraction and high seeding density. Finally, by this method thin nanocrystalline diamond films are achieved on Cr surfaces after O2 and CF4 plasma pretreatments.

  6. Accumulative coupling between magnetized tenuous plasma and gravitational waves

    NASA Astrophysics Data System (ADS)

    Zhang, Fan

    2017-01-01

    This talk presents solutions to the plasma waves induced by a plane gravitational wave (GW) train travelling through a region of strongly magnetized plasma. The computations constitute a very preliminary feasibility study for a possible ultra-high frequency gravitational wave detector, meant to take advantage of the observation that the plasma current is proportional to the GW amplitude, and not its square. This work is supported in part by NSFC Grant Number 11503003.

  7. A Concept for Directly Coupled Pulsed Electromagnetic Acceleration of Plasmas

    NASA Technical Reports Server (NTRS)

    Thio, Y.C. Francis; Cassibry, Jason T.; Eskridge, Richard; Smith, James; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    Plasma jets with high momentum flux density are required for a variety of applications in propulsion research. Methods of producing these plasma jets are being investigated at NASA Marshall Space Flight Center. The experimental goal in the immediate future is to develop plasma accelerators which are capable of producing plasma jets with momentum flux density represented by velocities up to 200 km/s and ion density up to 10(exp 24) per cu m, with sufficient precision and reproducibility in their properties, and with sufficiently high efficiency. The jets must be sufficiently focused to allow them to be transported over several meters. A plasma accelerator concept is presented that might be able to meet these requirements. It is a self-switching, shaped coaxial pulsed plasma thruster, with focusing of the plasma flow by shaping muzzle current distribution as in plasma focus devices, and by mechanical tapering of the gun walls. Some 2-D MHD modeling in support of the conceptual design will be presented.

  8. Inductively Coupled Plasma-Mass Spectrometry and the European Discovery of America

    NASA Astrophysics Data System (ADS)

    Houk, R. S.

    2000-05-01

    The background and initial experimental results in inductively coupled plasma-mass spectrometry (ICP-MS) are juxtaposed with similar events from the voyages of Christopher Columbus, particularly with the first voyage.

  9. Inductively Coupled Plasma Mass Spectrometry and the Determination of Neptunium and Plutonium in the Marine Environment

    NASA Astrophysics Data System (ADS)

    Sampson, Kate

    This project is concerned with the application of inductively coupled plasma mass spectrometry (ICP-MS) to the determination of neptunium-237, plutonium-239 and plutonium-240 concentrations in the marine environment…

  10. Effects of capacitance termination of the internal antenna in inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Konishi, K.; Nakamura, K.; Sugai, H.

    2000-05-01

    In a conventional inductive rf discharge, the electrostatic coupling from the coil to the plasma causes a serous problem of sputtering of any dielectric materials in the vicinity of the coil. This paper reports the suppression of the electrostatic coupling by terminating the coil (inductance L ) with a capacitor (capacitance C ). The suppression resonantly takes place when the termination reactance (1/icons/Journals/Common/omega" ALT="omega" ALIGN="TOP"/> C ) coincides with a half of the coil reactance (icons/Journals/Common/omega" ALT="omega" ALIGN="TOP"/> L ). In this condition, the plasma density is observed to increase by ~50% at the same input power, in comparison with the conventional internal antenna inductively coupled plasma without the capacitance termination. The electrical transmission-line properties of the coil well account for the termination capacitance dependence of the coil voltages, currents, plasma potential oscillation, plasma density and dc self-bias voltage.

  11. Instability and dynamics of two nonlinearly coupled laser beams in a two-temperature electron plasma.

    PubMed

    Eliasson, B; Shukla, P K

    2006-10-01

    We consider nonlinear interactions between two colliding laser beams in an electron plasma, accounting for the relativistic electron mass increase in the laser fields and radiation pressure driven electron-acoustic (EA) perturbations that are supported by hot and cold electrons. By using the hydrodynamic and Maxwell equations, we obtain the relevant equations for nonlinearly coupled laser beams and EA perturbations. The coupled equations are then Fourier analyzed to obtain a nonlinear dispersion relation. The latter is numerically solved to show the existence of new classes of the parametric instabilities in the presence of two colliding laser beams in a two-electron plasma. The dynamics of nonlinearly coupled laser beams in our electron plasma is also investigated. The results should be useful in understanding the nonlinear propagation characteristics of multiple electromagnetic beams in laser-produced plasmas as well as in space plasmas.

  12. Coupled microwave ECR and radio-frequency plasma source for plasma processing

    DOEpatents

    Tsai, C.C.; Haselton, H.H.

    1994-03-08

    In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm[sup 2] at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance. 4 figures.

  13. Coupled microwave ECR and radio-frequency plasma source for plasma processing

    DOEpatents

    Tsai, Chin-Chi; Haselton, Halsey H.

    1994-01-01

    In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm.sup.2 at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance.

  14. Transient three-dimensional dynamics of argon plasma within the vacuum interface of the inductively coupled plasma mass spectrometer system

    NASA Astrophysics Data System (ADS)

    Nagulin, K. Yu.; Tsivilskiy, I. V.; Akhmetshin, D. Sh.; Gilmutdinov, A. Kh.

    2017-09-01

    A three-dimensional transient mathematical model of the ;inductively coupled plasma - vacuum interface of the mass spectrometer; system was developed. The model takes into account spatial and temporal dynamics of hot gas flow (plasma emulation) and allows calculation of evolution of spatial distribution of pressure, velocity and temperature fields outside and within the interface of the mass-spectrometer. The results of modeling are verified using the experimental setup of high-speed optical and schlieren visualization of gas flows.

  15. Plasma characteristics in inductively and capacitively coupled hybrid source using single RF power

    NASA Astrophysics Data System (ADS)

    Kim, Kwan-Yong; Lee, Moo-Young; Kim, Tae-Woo; Kim, Ju-Ho; Chung, Chin-Wook

    2016-09-01

    Parallel combined inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) using single RF generator was proposed to linear control of the plasma density with RF power. In the case of ICP, linear control of the plasma density is difficult because there is a density jump up due to E to H transition. Although the plasma density of CCP changes linearly with power, the density is lower than that of ICP due to high ion energy loss at the substrate. In our hybrid source, the single RF power generator was connected to electrode and antenna, and the variable capacitor was installed between the antenna and the power generator to control the current flowing through the antenna and the electrode. By adjusting the current ratio between the antenna and the electrode, linear characteristic of plasma density with RF power is achieved.

  16. Experimental investigations of LHW-plasma coupling and current drive related to achieving H-mode plasmas in EAST

    NASA Astrophysics Data System (ADS)

    Ding, B. J.; Kong, E. H.; Li, M. H.; Zhang, Lei; Wei, W.; Wang, M.; Xu, H. D.; Li, Y. C.; Ling, B. L.; Zang, Q.; Xu, G. S.; Han, X. F.; Zhao, H. L.; Zhang, Ling; Zhao, L. M.; Hu, H. C.; Yang, Y.; Liu, L.; Ekedahl, A.; Goniche, M.; Cesario, R.; Peysson, Y.; Decker, J.; Basiuk, V.; Huynh, P.; Artaud, J.; Imbeaux, F.; Shan, J. F.; Liu, F. K.; Zhao, Y. P.; Gong, X. Z.; Hu, L. Q.; Gao, X.; Guo, H. Y.; Wan, B. N.; Li, J. G.; the EAST Team

    2013-11-01

    Aimed at high-confinement (H-mode) plasmas in the Experimental Advanced Superconducting Tokamak (EAST), the effect of local gas puffing from electron and ion sides of a lower hybrid wave (LHW) antenna on LHW-plasma coupling and high-density experiments with lower hybrid current drive (LHCD) are investigated in EAST. Experimental results show that gas puffing from the electron side is more favourable to improve coupling compared with gas puffing from the ion side. Investigations indicate that LHW-plasma coupling without gas puffing is affected by the density near the LHW grill (grill density), hence leading to multi-transition of low-high-low (L-H-L) confinement, with a correspondingly periodic characteristic behaviour in the plasma radiation. High-density experiments with LHCD suggest that strong lithiation gives a significant improvement on current drive efficiency in the higher density region than 2 × 1019 m-3. Studies indicate that the sharp decrease in current drive efficiency is mainly correlated with parametric decay instability. Using lithium coating and gas puffing from the electron side of the LHW antenna, an H-mode plasma is obtained by LHCD in a wide range of parameters, whether LHW is deposited inside the half-minor radius or not, implying that a central and large driven current is not a necessary condition for the H-mode plasma. H-mode is investigated with CRONOS.

  17. Early Time, Fast Collisional Dynamics of Equilibriating Ions in a Strongly Coupled Ultracold Neutral Plasma

    NASA Astrophysics Data System (ADS)

    Strickler, Trevor; McQuillen, Patrick; Langin, Thomas; Killian, Thomas; Bannasch, Georg; Pohl, Thomas

    2014-05-01

    Collision rates in weakly-coupled plasmas are well-described by the Landau-Spitzer formula. In the regime of strong coupling, however, the formula breaks down. This has motivated much theoretical and experimental work to study collision rates in strongly-coupled plasmas. In previous work, we have demonstrated direct measurements of thermalization rates in strongly-coupled ultracold neutral plasmas (UCNPs) created by photoionizing strontium atoms in magneto-optical trap. Our technique used optical pumping to create spin ``tagged'' subpopulations of ions having skewed velocity distributions. With LIF imaging, we measured the equilibration of the skewed velocity profiles to extract ion collision rates. We are now using these techniques to explore the early time dynamics of these skewed ion velocity distributions in the first 100ns after optical pumping. Molecular dynamics simulations of strongly coupled plasmas predict deviations from the exponential decay of average skewed velocity that is expected for weakly coupled plasmas. We use probe laser pulses on the order of 30ns to measure the relaxation of the skewed velocity profiles to test the theoretical predictions. This work was supported by the United States National Science Foun- dation and Department of Energy Partnership in Basic Plasma Science and Engineering (PHY-1102516) and the Air Force Office of Scientific Research (FA9550-12-1-0267).

  18. Complex image method for RF antenna-plasma inductive coupling calculation in planar geometry. Part I: basic concepts

    NASA Astrophysics Data System (ADS)

    Howling, A. A.; Guittienne, Ph; Jacquier, R.; Furno, I.

    2015-12-01

    The coupling between an inductive source and the plasma determines the power transfer efficiency and the reflected impedance in the primary circuit. Usually, the plasma coupling is analysed by means of a transformer equivalent circuit, where the plasma inductance and resistance are estimated using a global plasma model. This paper shows that, for planar RF antennas, the mutual inductance between the plasma and the primary circuit can be calculated using partial inductances and the complex image method, where the plasma coupling is determined in terms of the plasma skin depth and the distance to the plasma. To introduce the basic concepts, the mutual inductance is calculated here for a linear conductor parallel to the plasma surface. In the accompanying paper part II Guittienne et al (2015 Plasma Sources Sci. Technol. 24 065015), impedance measurements on a RF resonant planar plasma source are modeled using an impedance matrix where the plasma-antenna mutual impedances are calculated using the complex image method presented here.

  19. Ion flux and ion distribution function measurements in synchronously pulsed inductively coupled plasmas

    SciTech Connect

    Brihoum, Melisa; Cunge, Gilles; Darnon, Maxime; Joubert, Olivier; Gahan, David; Braithwaite, Nicholas St. J.

    2013-03-15

    Changes in the ion flux and the time-averaged ion distribution functions are reported for pulsed, inductively coupled RF plasmas (ICPs) operated over a range of duty cycles. For helium and argon plasmas, the ion flux increases rapidly after the start of the RF pulse and after about 50 {mu}s reaches the same steady state value as that in continuous ICPs. Therefore, when the plasma is pulsed at 1 kHz, the ion flux during the pulse has a value that is almost independent of the duty cycle. By contrast, in molecular electronegative chlorine/chlorosilane plasmas, the ion flux during the pulse reaches a steady state value that depends strongly on the duty cycle. This is because both the plasma chemistry and the electronegativity depend on the duty cycle. As a result, the ion flux is 15 times smaller in a pulsed 10% duty cycle plasma than in the continuous wave (CW) plasma. The consequence is that for a given synchronous RF biasing of a wafer-chuck, the ion energy is much higher in the pulsed plasma than it is in the CW plasma of chlorine/chlorosilane. Under these conditions, the wafer is bombarded by a low flux of very energetic ions, very much as it would in a low density, capacitively coupled plasma. Therefore, one can extend the operating range of ICPs through synchronous pulsing of the inductive excitation and capacitive chuck-bias, offering new means by which to control plasma etching.

  20. Helicon wave coupling in KSTAR plasmas for off-axis current drive in high electron pressure plasmas

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Wi, H. H.; Kim, H. J.; Kim, J.; Jeong, J. H.; Kwak, J. G.

    2017-04-01

    A helicon wave current drive is proposed as an efficient off-axis current drive in the high electron β plasmas that are expected in fusion reactors. A high frequency helicon wave coupling was analyzed using the surface impedance at a plasma boundary. A slow wave coupling, which may compete with the helicon wave coupling at a frequency of 500 MHz, is estimated to be lower than the fast wave coupling by an order of magnitude in the KSTAR edge plasma density and in practical Faraday shield misalignment with the magnetic pitch. A traveling wave antenna, which is a two port combline antenna, was analyzed using a simplified lumped element model. The results show that the traveling wave antenna provides load resiliency because of its insensitivity to loading resistance, provided that the loading resistance at a radiating element is limited within a practical range. The combline antenna is attractive because it does not require a matching system and exhibits a high selectivity of parallel refractive index. Based on the analysis, a seven element combline antenna was fabricated and installed at an off-mid-plane offset of 30 cm from the mid-plane in KSTAR. The low power RF characteristics measured during several plasma discharges showed no evidence of slow wave coupling. This is consistent with the expectation made through the surface impedance analysis which predicted low slow wave coupling. The wave coupling to the plasma is easily controlled by a radial outer-gap control and gas puffing. No plasma confinement degradation was observed during the radial outer-gap control of up to 3 cm in H-mode discharges. In a ELMy plasmas, only a small reflection peak was observed during a very short portion of the ELM bursting period. If the number of radiating elements is increased for high power operation, then complete load resiliency can be expected. A very large coupling can be problematic for maintaining a parallel refractive index, although this issue can be mitigated by

  1. Dynamic dipole polarizabilities of H- and Ps- in weakly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kar, Sabyasachi; Li, H. W.; Jiang, Pinghui

    2013-08-01

    The effects of weakly coupled plasmas on the dynamic dipole polarizabilities of the H- and Ps- ions are investigated using highly correlated exponential wave functions. The Debye-Hückel shielding approach of plasma modeling is used to represent weakly coupled plasma environments. In free-atomic cases, results obtained from the present study for H- are in agreement with the available calculations and results for Ps- are reported for the first time. Frequency-dependent polarizabilities of H- and Ps- as functions of screening parameter are also presented for the first time.

  2. Absolute vacuum ultraviolet flux in inductively coupled plasmas and chemical modifications of 193 nm photoresist

    NASA Astrophysics Data System (ADS)

    Titus, M. J.; Nest, D.; Graves, D. B.

    2009-04-01

    Vacuum ultraviolet (VUV) photons in plasma processing systems are known to alter surface chemistry and may damage gate dielectrics and photoresist. We characterize absolute VUV fluxes to surfaces exposed in an inductively coupled argon plasma, 1-50 mTorr, 25-400 W, using a calibrated VUV spectrometer. We also demonstrate an alternative method to estimate VUV fluence in an inductively coupled plasma (ICP) reactor using a chemical dosimeter-type monitor. We illustrate the technique with argon ICP and xenon lamp exposure experiments, comparing direct VUV measurements with measured chemical changes in 193 nm photoresist-covered Si wafers following VUV exposure.

  3. Stopping power of strongly coupled electronic plasmas: sum rules and asymptotic forms.

    PubMed

    Ortner, J; Tkachenko, I M

    2001-02-01

    The stopping power of coupled electronic plasmas is investigated. Within the dielectric formalism and employing the method of frequency moments for the dielectric function we obtain a general formula describing the linear stopping power of a coupled plasma. Analytical results for the low- and high-projectile-velocity asymptotic forms are obtained. A sum rule for the plasma heavy ions linear stopping power projectile velocity distribution is established to be related to the dielectric permeability "negative" frequency moment. This permits for a simple interpretation of stopping power data.

  4. Experimental Characterization of Dual-Frequency Capacitively Coupled Plasma with Inductive Enhancement in Argon

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Jin, Chenggang; Yu, Tao; Wu, Xuemei; Zhuge, Lanjian; Ning, Zhaoyuan; Ye, Chao; Ge, Shuibing

    2013-10-01

    The dual-frequency capacitively coupled plasma (DF-CCP) with inductive enhancement system is a newly designed plasma reactor. Different from the conventional inductively coupled plasma (ICP) reactors, now a radio frequency (rf) power is connected to an antenna placed outside the chamber with a one-turn bare coil placed between two electrodes in DF-CCP. This paper gives a detailed description of its structure. Moreover, investigations on some characteristics of discharges in this apparatus were made via a Langmuir probe.

  5. A Study on Reactive Ion Etching of Barium Strontium Titanate Films Using Mixtures of Argon (Ar), Carbon Tetrafluoride (CF4), and Sulfur Hexafluoride (SF6)

    DTIC Science & Technology

    2014-07-01

    utilizing self-aligned etching to create metal-insulator-metal ( MIM ) varactors. As part of this method we employed reactive ion etching (RIE) to remove BST...metal ( MIM ) varactors. Typically, dry etching techniques use a radio frequency (RF) power supply to place a high-frequency voltage difference between two...used in various concentrations with carbon tetrafluoride (CF4) and sulfur hexafluoride (SF6) to construct MIM varactors, made of Pt/BST/Pt* on sapphire

  6. MICROSCALE FLOW INJECTION AND MICROBORE HIGH-PERFORMANCE LIQUID CHROMATORGRAPHY COUPLED WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY VIA A HIGH-EFFICIENCY NEBULIZER

    EPA Science Inventory

    A high-effeciency nebulizer has been used for coupling microscale flow injection and microbore high-performance liquid chromatography with inductively coupled plasma mass spectrometry (ICPMS). The microscale flow injection system was configured to minimize band broadening between...

  7. An unambiguous signature in molecular frame photoelectron angular distributions of core hole localization in fluorine K-edge photoionization of CF4

    NASA Astrophysics Data System (ADS)

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; Lucchese, R. R.

    2016-05-01

    Molecular Frame Photoelectron Angular Distributions (MFPADs) are calculated using the Complex Kohn variational method for core-hole ionization of the carbon and fluorines in CF4 at photoelectron energies below 15 eV. The angular distributions for localized versus delocalized core-hole creation on the four equivalent fluorines are radically different. A strong propensity for the dissociation to take place via the mechanism hν +CF4 -->CF 4 + +e- -->CF 3 + +F(1s-1) -->CF 3 + +F+ + 2e- in which a core excited neutral fluorine atom ionizes during or after dissociation creates the conditions for experimental observation of core hole localization. Comparison with recent unpublished experiments at the Advanced Light Source that measured the Recoil Frame Photoelectron Angular Distributions (averaged over CF3 rotations around the recoil axis) for fluorine K-edge ionization gives unambiguous evidence that these experiments directly observed the creation of an almost completely localized core hole on the dissociating fluorine atom when the molecule was initially photoionized. Work supported by USDOE, OBES Chemical Sciences, Geosciences, and Biosciences Division.

  8. Comparison of pressure dependence of electron energy distributions in oxygen capacitively and inductively coupled plasmas.

    PubMed

    Lee, Min-Hyong; Lee, Hyo-Chang; Chung, Chin-Wook

    2010-04-01

    Electron energy distribution functions (EEDFs) were measured with increasing gas pressure in oxygen capacitively and inductively coupled plasmas. It was found that, in the capacitive discharge, abnormally low-energy electrons became highly populated and the EEDF evolved to a more distinct bi-Maxwellian distribution as the gas pressure was increased. This pressure dependence of the EEDF in the oxygen capacitive discharge is contrary to argon capacitively coupled plasma, where--at high gas pressure--low-energy electrons are significantly reduced due to collisional heating and the EEDF evolves to the Maxwellian. The highly populated low-energy electrons at high gas pressure, which was not observed in inductively coupled oxygen plasma, show that collisional heating is very inefficient in terms of the oxygen capacitive discharge. It appears that this inefficient collisional heating seems to be attributed to a low electric field strength at the center of the oxygen capacitive plasma.

  9. PIC/MCC simulation for magnetized capacitively coupled plasmas driven by combined dc/rf sources

    NASA Astrophysics Data System (ADS)

    Yang, Shali; Zhang, Ya; Jiang, Wei; Wang, Hongyu; Wang, Shuai

    2016-09-01

    Hybrid dc/rf capacitively coupled plasma (CCP) sources have been popular in substrate etching due to their simplicity in the device structure and better plasma property. In this work, the characteristics of magnetized capacitively coupled plasmas driven by combined dc/rf sources are described by a one-dimensional Particle-in-cell/Monte Carlo collision (PIC/MCC) model. The simulation is using a rf source of 13.56MHz in argon and at a low pressure of 50mTorr. The effects of dc voltage and magnetic field on the plasmas are examined for 200-400V and 0-200Gs. It is found that, to some extent, dc voltage will increase the plasma density, but plasma density drops with increasing dc voltage. The magnetic field will enhance the plasma density significantly, due to the magnetic field will increase the electron life time and decrease the loss to the electrodes. In the bulk plasma, electron temperature is increased with the magnetic field but decreased with the dc voltage. The electron temperature in sheath is higher than in bulk plasma, due to stochastic heating in sheath is greater than Ohmic heating in bulk plasma under low gas pressure. National Natural Science Foundation of China (11405067, 11105057, 11305032, 11275039).

  10. A comprehensive study of different gases in inductively coupled plasma torch operating at one atmosphere

    SciTech Connect

    Punjabi, Sangeeta B.; Joshi, N. K.; Mangalvedekar, H. A.; Lande, B. K.; Das, A. K.; Kothari, D. C.

    2012-01-15

    A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent{sup (c)}. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications.

  11. A comprehensive study of different gases in inductively coupled plasma torch operating at one atmosphere

    NASA Astrophysics Data System (ADS)

    Punjabi, Sangeeta B.; Joshi, N. K.; Mangalvedekar, H. A.; Lande, B. K.; Das, A. K.; Kothari, D. C.

    2012-01-01

    A numerical study is done to understand the possible operating regimes of RF-ICP torch (3 MHz, 50 kW) using different gases for plasma formation at atmospheric pressure. A two dimensional numerical simulation of RF-ICP torch using argon, nitrogen, oxygen, and air as plasma gas has been investigated using computational fluid dynamic (CFD) software fluent©. The operating parameters varied here are central gas flow, sheath gas flow, RF-power dissipated in plasma, and plasma gas. The temperature contours, flow field, axial, and radial velocity profiles were investigated under different operating conditions. The plasma resistance, inductance of the torch, and the heat distribution for various plasma gases have also been investigated. The plasma impedance of ICP torch varies with different operating parameters and plays an important role for RF oscillator design and power coupling. These studies will be useful to decide the design criteria for ICP torches required for different material processing applications.

  12. Electric field enhanced conductivity in strongly coupled dense metal plasma

    SciTech Connect

    Stephens, J.; Neuber, A.

    2012-06-15

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field ({approx}6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  13. Electric field enhanced conductivity in strongly coupled dense metal plasma

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Neuber, A.

    2012-06-01

    Experimentation with dense metal plasma has shown that non-negligible increases in plasma conductivity are induced when a relatively low electric field (˜6 kV/cm) is applied. Existing conductivity models assume that atoms, electrons, and ions all exist in thermal equilibrium. This assumption is invalidated by the application of an appreciable electric field, where electrons are accelerated to energies comparable to the ionization potential of the surrounding atoms. Experimental data obtained from electrically exploded silver wire is compared with a finite difference hydrodynamic model that makes use of the SESAME equation-of-state database. Free electron generation through both thermal and electric field excitations, and their effect on plasma conductivity are applied and discussed.

  14. Self-diffusion, conductivity, and long-wavelength plasma oscillations in strongly coupled two-component plasmas

    NASA Astrophysics Data System (ADS)

    Sjogren, L.; Hansen, J. P.; Pollock, E. L.

    1981-09-01

    The autocorrelation functions of the microscopic electric current J(t) and the electron velocity Z2(t) are calculated for strongly coupled semiclassical two-component plasmas. The corresponding memory functions are expressed in terms of mode-coupling integrals involving density- and energy-correlation functions in the framework of a microscopic kinetic theory which preserves the exact statics. The theory is applied to weakly degenerate hydrogen and carbon plasmas for values of the plasma parameter of order 1. The resulting correlation functions J(t) and Z2(t) and their integrals, the electrical conductivity, and the electron self-diffusion constant, agree reasonably well with the molecular dynamics data of Hansen and McDonald and with additional simulation results presented here.

  15. Wave mode coupling due to plasma wakes in two-dimensional plasma crystals: In-depth view

    SciTech Connect

    Coueedel, L.

    2011-08-15

    Experiments with two-dimensional (2D) plasma crystals are usually carried out in rf plasma sheaths, where the interparticle interactions are modified due to the presence of plasma wakes. The wake-mediated interactions result in the coupling between wave modes in 2D crystals, which can trigger the mode-coupling instability and cause melting. The theory predicts a number of distinct fingerprints to be observed upon the instability onset, such as the emergence of a new hybrid mode, a critical angular dependence, a mixed polarization, and distinct thresholds. In this paper we summarize these key features and provide their detailed discussion, analyze the critical dependence on experimental parameters, and highlight the outstanding issues.

  16. Quarkonium in a weakly-coupled quark-gluon plasma

    SciTech Connect

    Vairo, Antonio

    2010-12-22

    We report about a recent calculation of the heavy quarkonium mass and decay width in a quark-gluon plasma, whose temperature T and screening mass m{sub D} satisfy the hierarchy m{alpha}{sub s}>>T>>m{alpha}{sub s}{sup 2}>>m{sub D}, m being the heavy-quark mass, up to order m{alpha}{sub s}{sup 5}. The calculation may be relevant to understand the behavior of the {Upsilon}(1S) in a quark-gluon plasma at present-day colliders.

  17. A study on improvement of discharge characteristic by using a transformer in a capacitively coupled plasma

    SciTech Connect

    Kim, Young-Cheol; Kim, Hyun-Jun; Lee, Hyo-Chang; Chung, Chin-Wook

    2015-12-15

    In a plasma discharge system, the power loss at powered line, matching network, and other transmission line can affect the discharge characteristics such as the power transfer efficiency, voltage and current at powered electrode, and plasma density. In this paper, we propose a method to reduce power loss by using a step down transformer mounted between the matching network and the powered electrode in a capacitively coupled argon plasma. This step down transformer decreases the power loss by reducing the current flowing through the matching network and transmission line. As a result, the power transfer efficiency was increased about 5%–10% by using a step down transformer. However, the plasma density was dramatically increased compared to no transformer. This can be understood by the increase in ohmic heating and the decrease in dc-self bias. By simply mounting a transformer, improvement of discharge efficiency can be achieved in capacitively coupled plasmas.

  18. Experimental and numerical studies of neutral gas depletion in an inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Shimada, Masashi

    The central theme of this dissertation is to explore the impact of neutral depletion and coupling between plasma and neutral gas in weakly ionized unmagnetized plasma. Since there have been few systematic studies of the mechanism which leads to non-uniform neutral distribution in processing plasmas, this work investigated the spatial profiles of neutral temperature and pressure experimentally, and the mechanism of resulting neutral depletion by simulation. The experimental work is comprised of neutral temperature measurements using high resolution atomic spectroscopy and molecular spectroscopy, and neutral pressure measurements considering thermal transpiration. When thermal transpiration effects are used to correct the gas pressure measurements, the total pressure remains constant regardless of the plasma condition. Since the neutral gas follows the ideal gas law, the neutral gas density profile is also obtained from the measured neutral gas temperature and the corrected pressure measurements. The results show that neutral gas temperature rises close to ˜ 900 [K], and the neutral gas density at the center of plasma chamber has a significant (factor of 2-4x) decrease in the presence of a plasma discharge. In numerical work, neutral and ion transport phenomena were simulated by a hybrid-type direct simulation Monte Carlo (DSMC) method of one dimensional (1D) electrostatic plasma to identify the mechanism of the neutral gas density depletion in Ar/N2 mixtures. The simulation reveals that the neutral depletion is the result of the interplay between plasma and neutral gas, and a parametric study indicates that neutral depletion occurs mainly due to gas heating and pressure balance for the typical condition of plasma processing. In high density plasma sources (Te ≈ 2-5 eV, ne ≈ 1011-1012 cm-3) where the plasma pressure becomes comparable to neutral pressure, total pressure (neutral pressure and plasma pressure) is conserved before and after the discharge. Therefore

  19. An open-ended coaxial plasma source with extended operating parameters: plasma impedance, coupling and energy efficiency

    NASA Astrophysics Data System (ADS)

    Baële, Pierre; Béchu, Stéphane; Bès, Alexandre; Pelletier, Jacques; Lacoste, Ana

    2014-12-01

    The coupling modes and efficiency in terms of transmitted and absorbed powers were studied using an open-ended microwave applicator (MWA) provided with a magnet. This configuration allowed the acquirement and investigation of plasmas over four decades in pressure, from 10-4 to a few torrs, for powers up to 200 W. Plasma impedance measurements revealed different coupling modes and transitions from the capacitive to the inductive mode. These also permitted the unraveling of the conditions for which maximum power and heating efficiencies can be obtained, which were found to be primarily linked with the resistive coupling. Moreover, the MWA was seen to be effective in extending the domains of pressures (1-50 mTorr) and powers (higher than 60 W), maintaining at least 80% of the transmitted/absorbed power within the working range. However, by knowing the values of impedance for different pressures, the MWA design can be adjusted for other domains as well.

  20. Antenna-plasma coupling theory for ICRF heating of large tokamaks

    SciTech Connect

    Ram, A.; Bers, A.

    1982-03-01

    The coupling characteristics of antenna structure are studied by analyzing a model where a thin current sheet is placed between a fully conducting wall and a sheet of anisotropic conductivity representing the screen. The inhomogeneous plasma in the shadow of the limiter is assumed to extend from the screen onwards away from the antenna. The excitation of the fields inside the plasma are found by analyzing the radiation properties of this current sheet antenna. We assume that the current distribution of the antenna is given and that the fields excited inside the plasma are absorbed in a single pass. In all experiments to-date the cross-sectional plasmas are relatively small so that the rf conductor is a half-loop around the plasma in the poloidal direction. However, for reactor size plasmas this cannot be done and the antenna dimensions will be small compared to the plasma cross-sections. We, thus, assume an antenna of finite poloidal and toroidal extent with dimensions small compared to the plasma minor radius. We further approximate the coupling geometry by a slab model. The x-axis is taken to be along the plasma inhomogeneity, the y-axis along the poloidal direction and the x-axis along the toroidal magnetic field.

  1. Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

    SciTech Connect

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.; Kakati, M.

    2011-10-15

    Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure.

  2. On the possibility of the multiple inductively coupled plasma and helicon plasma sources for large-area processes

    SciTech Connect

    Lee, Jin-Won; Lee, Yun-Seong Chang, Hong-Young; An, Sang-Hyuk

    2014-08-15

    In this study, we attempted to determine the possibility of multiple inductively coupled plasma (ICP) and helicon plasma sources for large-area processes. Experiments were performed with the one and two coils to measure plasma and electrical parameters, and a circuit simulation was performed to measure the current at each coil in the 2-coil experiment. Based on the result, we could determine the possibility of multiple ICP sources due to a direct change of impedance due to current and saturation of impedance due to the skin-depth effect. However, a helicon plasma source is difficult to adapt to the multiple sources due to the consistent change of real impedance due to mode transition and the low uniformity of the B-field confinement. As a result, it is expected that ICP can be adapted to multiple sources for large-area processes.

  3. Observation of helicon wave with m = 0 antenna in a weakly magnetized inductively coupled plasma source

    NASA Astrophysics Data System (ADS)

    Ellingboe, Bert; Sirse, Nishant; Moloney, Rachel; McCarthy, John

    2015-09-01

    Bounded whistler wave, called ``helicon wave,'' is known to produce high-density plasmas and has been exploited as a high density plasma source for many applications, including electric propulsion for spacecraft. In a helicon plasma source, an antenna wrapped around the magnetized plasma column launches a low frequency wave, ωce/2 >ωhelicon >ωce/100, in the plasma which is responsible for maintaining high density plasma. Several antenna designs have been proposed in order to match efficiently the wave modes. In our experiment, helicon wave mode is observed using an m = 0 antenna. A floating B dot probe, compensated to the capacitively coupled E field, is employed to measure axial-wave-field-profiles (z, r, and θ components) in the plasma at multiple radial positions as a function of rf power and pressure. The Bθ component of the rf-field is observed to be unaffected as the wave propagates in the axial direction. Power coupling between the antenna and the plasma column is identified and agrees with the E, H, and wave coupling regimes previously seen in M =1 antenna systems. That is, the Bz component of the rf-field is observed at low plasma density as the Bz component from the antenna penetrates the plasma. The Bz component becomes very small at medium density due to shielding at the centre of the plasma column; however, with increasing density, a sudden ``jump'' occurs in the Bz component above which a standing wave under the antenna with a propagating wave away from the antenna are observed.

  4. New approach to the determination phosphorothioate oligonucleotides by ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry.

    PubMed

    Studzińska, Sylwia; Mounicou, Sandra; Szpunar, Joanna; Łobiński, Ryszard; Buszewski, Bogusław

    2015-01-15

    This text presents a novel method for the separation and detection of phosphorothioate oligonucleotides with the use of ion pair ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry The research showed that hexafluoroisopropanol/triethylamine based mobile phases may be successfully used when liquid chromatography is coupled with such elemental detection. However, the concentration of both HFIP and TEA influences the final result. The lower concentration of HFIP, the lower the background in ICP-MS and the greater the sensitivity. The method applied for the analysis of serum samples was based on high resolution inductively coupled plasma mass spectrometry. Utilization of this method allows determination of fifty times lower quantity of phosphorothioate oligonucleotides than in the case of quadrupole mass analyzer. Monitoring of (31)P may be used to quantify these compounds at the level of 80 μg L(-1), while simultaneous determination of sulfur is very useful for qualitative analysis. Moreover, the results presented in this paper demonstrate the practical applicability of coupling LC with ICP-MS in determining phosphorothioate oligonucleotides and their metabolites in serum within 7 min with a very good sensitivity. The method was linear in the concentration range between 0.2 and 3 mg L(-1). The limit of detection was in the range of 0.07 and 0.13 mg L(-1). Accuracy varied with concentration, but was in the range of 3%. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Coupled two-dimensional edge plasma and neutral gas modeling of tokamak scrape-off-layers

    SciTech Connect

    Maingi, R.

    1992-08-01

    The objective of this study is to devise a detailed description of the tokamak scrape-off-layer (SOL), which includes the best available models of both the plasma and neutral species and the strong coupling between the two in many SOL regimes. A good estimate of both particle flux and heat flux profiles at the limiter/divertor target plates is desired. Peak heat flux is one of the limiting factors in determining the survival probability of plasma-facing-components at high power levels. Plate particle flux affects the neutral flux to the pump, which determines the particle exhaust rate. A technique which couples a two-dimensional (2-D) plasma and a 2-D neutral transport code has been developed (coupled code technique), but this procedure requires large amounts of computer time. Relevant physics has been added to an existing two-neutral-species model which takes the SOL plasma/neutral coupling into account in a simple manner (molecular physics model), and this model is compared with the coupled code technique mentioned above. The molecular physics model is benchmarked against experimental data from a divertor tokamak (DIII-D), and a similar model (single-species model) is benchmarked against data from a pump-limiter tokamak (Tore Supra). The models are then used to examine two key issues: free-streaming-limits (ion energy conduction and momentum flux) and the effects of the non-orthogonal geometry of magnetic flux surfaces and target plates on edge plasma parameter profiles.

  6. Cleaning of optical surfaces by capacitively coupled RF discharge plasma

    SciTech Connect

    Yadav, P. K. Rai, S. K.; Nayak, M.; Lodha, G. S.; Kumar, M.; Chakera, J. A.; Naik, P. A.; Mukherjee, C.

    2014-04-24

    In this paper, we report cleaning of carbon capped molybdenum (Mo) thin film by in-house developed radio frequency (RF) plasma reactor, at different powers and exposure time. Carbon capped Mo films were exposed to oxygen plasma for different durations at three different power settings, at a constant pressure. After each exposure, the thickness of the carbon layer and the roughness of the film were determined by hard x-ray reflectivity measurements. It was observed that most of the carbon film got removed in first 15 minutes exposure. A high density layer formed on top of the Mo film was also observed and it was noted that this layer cannot be removed by successive exposures at different powers. A significant improvement in interface roughness with a slight improvement in top film roughness was observed. The surface roughness of the exposed and unexposed samples was also confirmed by atomic force microscopy measurements.

  7. Studies on Mixed-Gas Plasmas and Segmented Flow Injection for Use with Inductively Coupled Plasma Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Craig, Jane Mary

    In this thesis, mixed gas plasmas and flow injection into air bubbles were investigated for use with inductively coupled plasma mass spectrometry (ICP-MS), in order to improve the technique's analytical capabilities. The mixed gas plasmas were created in two different ways: (i) by adding another gas, either argon, nitrogen, or hydrogen, to the nebulizer gas flow using a sheathing device or (ii) by adding nitrogen to the plasma gas flow. The introduction of each sheathing gas led to degraded analyte sensitivity but generally improved plasma stability, resulting in improved detection limits for a few elements. Introduction of nitrogen into the plasma gas, under the same operating conditions used for an all-argon plasma, resulted in degraded sensitivity but improved signal-to-noise and signal-to-background ratios for Cr, Fe, and Se. The tolerance of ICP-MS to effects caused by the concomitant elements Na and K was improved by addition of nitrogen to the plasma gas flow. Flow injection using a segmented air/water carrier resulted in improved precision, sensitivity, and detection limits compared to those obtained using an all-water carrier. The enhancement in sensitivity was found to be mass dependent and was attributable to more than simply a reduction in dispersion. Under optimized operating conditions, using segmented flow injection resulted in similar or improved detection limits for all analytes except Se when compared to those obtained using continuous nebulization. Changing the gas used to segment the carrier stream did not result in appreciable changes in analyte signals or positions of maximum ionization within the plasma, indicating that the fundamental properties of the plasma did not change. The tolerance of ICP-MS to effects caused by the concomitant elements Na and Ca was not improved by using a segmented carrier compared to that experienced using an all-water carrier.

  8. Non-Equilibrium Modeling of Inductively Coupled RF Plasmas

    DTIC Science & Technology

    2015-01-01

    other provision of law , no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a...Navier-Stokes and Maxwell equa- tions [2]. In literature, the Local Thermodynamic Equi- librium (LTE) assumption is often used to describe the state of...the gas in the discharge region [4–17]. However, Non Local Thermodynamic Equilibrium (NLTE) simula- tions of Argon [18, 19] and air plasmas [20], have

  9. Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

    2016-09-01

    Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

  10. Radical electronic transformation of strongly coupled plasma at megabar pressure ionization, dielectrization and phase transitions

    NASA Astrophysics Data System (ADS)

    Fortov, Vladimir

    2007-06-01

    The work presents new results of investigation of pressure and temperature ionization of coupled nonideal plasmas generated as a result of multiple shock compression of metals, H2, He, noble gases, S, I, fullerene C60, H2O in the megabar pressure range. The highly time-resolved diagnostics permit us to measure thermodynamical, radiative and mechanical properties of high pressure condensed matter in a broad region of the phase diagram. This data in combination with exploding wire conductivity measurements demonstrate an ionization rate increase up to ten orders of magnitude as a result of compression of degenerate plasmas at p 104-107 bars. Shock compression of H2, Ar, He, Kr, Ne, Xe in initially gaseous and cryogenic liquid state allows measuring the electrical conductivity, Hall effect parameters, equation of state, and emission spectra of strongly nonideal plasma. Thermal and pressure ionization of strongly coupled states of matter is the most prominent effects under the experimental conditions. It was shown that plasma compression strongly deforms the ionization potentials, emission spectra and scattering cross-sections of the neutrals and ions in the strongly coupled plasmas. In contrast to the plasma compression the multiple shock compression of solid Li, Na, Ca shows ``dielectrization'' of the elements. Phase transitions in strongly nonideal plasmas are discussed.

  11. Nonlinear coupling of acoustic and shear mode in a strongly coupled dusty plasma with a density dependent viscosity

    NASA Astrophysics Data System (ADS)

    Garai, S.; Janaki, M. S.; Chakrabarti, N.

    2016-09-01

    The nonlinear propagation of low frequency waves, in a collisionless, strongly coupled dusty plasma (SCDP) with a density dependent viscosity, has been studied with a proper Galilean invariant generalized hydrodynamic (GH) model. The well known reductive perturbation technique (RPT) has been employed in obtaining the solutions of the longitudinal and transverse perturbations. It has been found that the nonlinear propagation of the acoustic perturbations govern with the modified Korteweg-de Vries (KdV) equation and are decoupled from the sheared fluctuations. In the regions, where transversal gradients of the flow exists, coupling between the longitudinal and transverse perturbations occurs due to convective nonlinearity which is true for the homogeneous case also. The results, obtained here, can have relative significance to astrophysical context as well as in laboratory plasmas.

  12. Characteristics of dual-frequency capacitively coupled SF6/O2 plasma and plasma texturing of multi-crystalline silicon

    NASA Astrophysics Data System (ADS)

    Xu, Dong-Sheng; Zou, Shuai; Xin, Yu; Su, Xiao-Dong; Wang, Xu-Sheng

    2014-06-01

    Due to it being environmentally friendly, much attention has been paid to the dry plasma texturing technique serving as an alternative candidate for multicrystalline silicon (mc-Si) surface texturing. In this paper, capacitively coupled plasma (CCP) driven by a dual frequency (DF) of 40.68 MHz and 13.56 MHz is first used for plasma texturing of mc-Si with SF6/O2 gas mixture. Using a hairpin resonant probe and optical emission techniques, DF-CCP characteristics and their influence on mc-silicon surface plasma texturing are investigated at different flow rate ratios, pressures, and radio-frequency (RF) input powers. Experimental results show that suitable plasma texturing of mc-silicon occurs only in a narrow range of plasma parameters, where electron density ne must be larger than 6.3 × 109 cm-3 and the spectral intensity ratio of the F atom to that of the O atom ([F]/[O]) in the plasma must be between 0.8 and 0.3. Out of this range, no cone-like structure is formed on the mc-silicon surface. In our experiments, the lowest reflectance of about 7.3% for mc-silicon surface texturing is obtained at an [F]/[O] of 0.5 and ne of 6.9 × 109 cm-3.

  13. Antenna-plasma coupling theory for ICRF heating of large tokamaks

    NASA Astrophysics Data System (ADS)

    Ram, A.; Bers, A.

    1982-03-01

    The coupling characteristics of antenna structure were studied by analyzing a model where a thin current sheet is placed between a fully conducting wall and a sheet of anisotropic conductivity representing the screen. The inhomogeneous plasma in the shadow of the limiter is assumed to extend from the screen onwards away from the antenna. The excitation of the fields inside the plasma are found by analyzing the radiation properties of this current sheet antenna. In all experiments to-date, the cross-sectional plasmas are relatively small so that the RF conductor is a half-loop around the plasma in the poloidal direction. For reactor size plasmas, this cannot be done and the antenna dimensions will be small compared to the plasma cross-sections.

  14. Impact of phase lag on uniformity in pulsed capacitively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Rauf, Shahid; Collins, Ken

    2011-07-11

    Process uniformity of macro-scale parameters such as electron and ion densities is critical during any plasma process. Pulsed operation of multiple frequency capacitively coupled plasmas (CCPs) has been shown to improve profile characteristics of features during plasma etching. In this work, we consider pulsing of both power sources in a dual frequency CCP. The impact of phase lag between the high frequency and low frequency power pulses on plasma uniformity is examined using a two-dimensional computational plasma model. Results for Ar/CF{sub 4} gas mixture indicate that phase lag allows one to control plasma uniformity by modulating the time for which the high or low frequency source is on.

  15. Capacitively coupled microwave plasma atomic emission spectrometer for the determination of lead in whole blood.

    PubMed

    Wensing, M W; Smith, B W; Winefordner, J D

    1994-02-15

    The determination of lead in whole blood by atomic emission spectrometry using a capacitively coupled microwave plasma and a tungsten filament electrode is presented. When the plasma-supporting electrode is also used as the sample holder, transfer of the sample to the plasma is 100%. Microwaves are used to dry the sample and, at higher powers, ignite a helium plasma which results in the atomization and excitation of Pb. Using this methodology, a detection limit of 3 pg of Pb was obtained using 5-microL aqueous samples. The precision was 9%. Whole blood samples were subjected to a drying stage similar to that of the aqueous samples. Following this drying stage, a low-power (30 W) helium plasma was ignited and used to ash the blood sample. Higher power plasmas (> 150 W) were used to atomize and excite the Pb. Recovery of Pb from the blood samples was 88%, when compared to aqueous standards.

  16. Control and analysis of ion species in inductively coupled nitration plasma using a grid system

    SciTech Connect

    Bai, K.H.; Chang, H.Y.

    2005-09-19

    We control the ion density ratio of [N{sup +}]/[N{sub 2}{sup +}] with the voltage-biased grid system in inductively coupled nitration plasma. The ion density ratio is controlled from 0.39 to 0.04 with decreasing grid-biased voltage. We try to analyze the variation of the ion density ratio using the measured plasma parameters and particle balance equation. The important factor determining the ion ratio is the plasma potential difference between the source region--where plasma is generated--and the diffusion region--where the electron temperature is controlled. When the plasma potential is higher in the source region than in diffusion region, the ion density ratio is determined by the electron temperature in Region I. Inversely, the ion density ratio is determined by the electron temperature in Region II, when the plasma potential is higher in Region II than in Region I.

  17. Influence of coupling on thermal forces and dynamic friction in plasmas with multiple ion species

    NASA Astrophysics Data System (ADS)

    Kagan, Grigory; Baalrud, Scott D.; Daligault, Jérôme

    2017-07-01

    The recently proposed effective potential theory [Phys. Rev. Lett. 110, 235001 (2013)] is used to investigate the influence of coupling on inter-ion-species diffusion and momentum exchange in multi-component plasmas. Thermo-diffusion and the thermal force are found to diminish rapidly as strong coupling onsets. For the same coupling parameters, the dynamic friction coefficient is found to tend to unity. These results provide an impetus for addressing the role of coupling on diffusive processes in inertial confinement fusion experiments.

  18. Comparative analysis of ancient ceramics by neutron activation analysis, inductively coupled plasma-optical-emission spectrometry, inductively coupled plasma-mass spectrometry, and X-ray fluorescence.

    PubMed

    Tsolakidou, Alexandra; Kilikoglou, Vassilis

    2002-10-01

    The accurate measurement of the maximum possible number of elements in ancient ceramic samples is the main requirement in provenance studies. For this reason neutron activation analysis (NAA) and X-ray fluorescence (XRF) have been successfully used for most of the studies. In this work the analytical performance of inductively coupled plasma-optical-emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) has been compared with that of XRF and NAA for the chemical characterization of archaeological pottery. Correlation coefficients between ICP techniques and XRF or NAA data were generally better than 0.90. The reproducibility of data calculated on a sample prepared and analysed independently ten times was approximately 5% for most of the elements. Results from the ICP techniques were finally evaluated for their capacity to identify the same compositional pottery groups as results from XRF and NAA analysis, by use of multivariate statistics.

  19. Studies on the effect of finite geometrical asymmetry in dual capacitively coupled radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Bora, B.

    2015-10-01

    In recent years, dual capacitively coupled radio frequency (CCRF) glow discharge plasma has been widely studied in the laboratory because of its simpler design and high efficiency for different material processing applications such as thin-film deposition, plasma etching, sputtering of insulating materials etc. The main objective of studies on dual frequency CCRF plasma has been the independent control of ion energy and ion flux using an electrical asymmetry effect (EAE). Most studies have been reported in electrode configurations that are either geometrically symmetric (both electrodes are equal) or completely asymmetric (one electrode is infinitely bigger than the other). However, it seems that most of the laboratory CCRF plasmas have finite electrode geometry. In addition, plasma series resonance (PSR) and electron bounce resonance (EBR) heating also come into play as a result of geometrical asymmetry as well as EAE. In this study, a dual frequency CCRF plasma has been studied in which the dual frequency CCRF has been coupled to the lumped circuit model of the plasma and the time-independent fluid model of the plasma sheath, in order to study the effect of finite geometrical asymmetry on the generation of dc-self bias and plasma heating. The dc self-bias is found to strongly depend on the ratio of the area between the electrodes. The dc self-bias is found to depend on the phase angle between the two applied voltage waveforms. The EAE and geometrical asymmetry are found to work differently in controlling the dc self-bias. It can be concluded that the phase angle between the two voltage waveforms in dual CCRF plasmas has an important role in determining the dc self-bias and may be used for controlling the plasma properties in the dual frequency CCRF plasma.

  20. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Formation of a coupled state in a laser plume

    NASA Astrophysics Data System (ADS)

    Kask, Nikolai E.; Michurin, Sergei V.; Fedorov, Gennadii M.; Chopornyak, D. B.

    2005-04-01

    The results of experimental investigation of a low-temperature plasma produced by laser irradiation at the surface of metal targets are reported. The optical characteristics and the plasma pressure in the laser plume are found to exhibit a threshold behaviour under vaporised-material density variation. The results are interpreted using the model of a coupled plasma state with limitation of plasma expansion.

  1. Theory of beat-resonant coupling of electrostatic modes. [in nonuniform Vlasov plasma

    NASA Technical Reports Server (NTRS)

    Crawford, John David; Kaufman, Allan N.; Oberman, Carl; Johnston, Shayne

    1986-01-01

    A general expression is derived for the beat-resonant coupling electrostatic modes in a Vlasov plasma. The result for the coupling of two modes has a simple structure: the appropriate momentum gradient of the equilibrium particle distribution is weighted by a positive coupling coefficient and averaged over the resonance surface in momentum space. The contributions of all the resonance surfaces are then summed. This basic structure had been previously exhibited only for specific homogeneous plasma models. The present theory, which unifies and greatly simplifies these individual treatments, is based on a variational formulation of the Vlasov-Poisson equations. Using Lie transforms, the variational principle is reexpressed in oscillation-center variables, and then the nonlinear wave dynamics are obtained from the independent variations of the wave phase and the wave amplitude. The power of the method is then applied to a strongly magnetized, strongly inhomogeneous, non-neutral plasma model.

  2. Effect of the driving frequency on a VHF capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroyuki; Yagisawa, Takashi; Makabe, Toshiaki

    2007-10-01

    In the next-generation ULSI process, a capacitively coupled VHF (UHF) plasma will be employed in order to obtain higher plasma density with large size of electrodes (˜ m). Then the system will be subject to the strong electromagnetic effect, such as a standing wave and a skin effect. The effect of the standing wave causes nonuniformity along the radial direction to the capacitively coupled plasma (CCP), when the size of the electrode is comparable to the wavelength of the VHF(UHF) voltage source on the electrode. In the present study, nonuniformity of the potential distribution is numerically investigated on a large electrode in the VHF-CCP in Ar in the cylindrical coordinate system (r, z) by using the combination between the transmission line model (TLM) and the relaxation continuum (RCT) model. The influence of potential nonuniformity on the plasma structure will be discussed in detail.

  3. Plasma cell differentiation is coupled to division-dependent DNA hypomethylation and gene regulation

    PubMed Central

    Bally, Alexander P.R.; Boss, Jeremy M.

    2016-01-01

    The epigenetic processes that regulate antibody secreting plasma cells are not well understood. Here, analysis of plasma cell differentiation revealed DNA hypomethylation of 10% of CpG loci that were overrepresented at enhancers. Inhibition of DNA methylation enhanced plasma cell commitment in a cell division-dependent manner. Examination of in vivo differentiating B cells stratified by cell division revealed a 5-fold increase in mRNA transcription coupled to DNA hypomethylation. Demethylation occurred first at binding motifs of NF-κB and AP-1 and later at those for IRF and Oct-2, and were coincident with activation and differentiation gene expression programs. These data provide mechanistic insight into the cell-division coupled transcriptional and epigenetic reprogramming and suggest DNA hypomethylation reflects the cis-regulatory history of plasma cell differentiation. PMID:27500631

  4. Strong Helioseismic Constraints on Weakly-Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Nayfonov, Alan

    The extraordinary accuracy of helioseismic data allows detailed theoretical studies of solar plasmas. The necessity to produce solar models matching the experimental results in accuracy imposes strong constrains on the equations of state of solar plasmas. Several discrepancies between the experimental data and models have been successfully identified as the signatures of various non-ideal phenomena. Of a particular interest are questions of the position of the energy levels and the continuum edge and of the effect of the excited states in the solar plasma. Calculations of energy level and continuum shifts, based on the Green function formalism, appeared recently in the literature. These results have been used to examine effects of the shifts on the thermodynamic quantities. A comparison with helioseismic data has shown that the calculations based on lower-level approximations, such as the static screening in the effective two-particle wave equation, agree very well with the experimental data. However, the case of full dynamic screening produces thermodynamic quantities inconsistent with observations. The study of the effect of different internal partition functions on a complete set of thermodynamic quantities has revealed the signature of the excited states in the MHD (Mihalas, Hummer, Dappen) equation of state. The presence of exited states causes a characteristic 'wiggle' in the thermodynamic quantities due to the density-dependent occupation probabilities. This effect is absent if the ACTEX (ACTivity EXpansion) equation of state is used. The wiggle has been found to be most prominent in the quantities sensitive to density. The size of this excited states effect is well within the observational power of helioseismology, and very recent inversion analyses of helioseismic data seem to indicate the presence of the wiggle in the sun. This has a potential importance for the helioseismic determination of the helium abundance of the sun.

  5. Mode coupling and evolution in broken-symmetry plasmas

    SciTech Connect

    Sherman, E. Ya.; Abrarov, R. M.; Sipe, J. E.

    2009-10-15

    The control of nonlinear processes and possible transitions to chaos in systems of interacting particles is a fundamental physical problem. We propose a nonuniform solid-state plasma system, produced by the optical injection of current in two-dimensional semiconductor structures, where this control can be achieved. Due to an injected current, the system symmetry is initially broken. The subsequent nonequilibrium dynamics is governed by the spatially varying long-range Coulomb forces and electron-hole collisions. As a result, inhomogeneities in the charge and velocity distributions should develop rapidly and lead to previously unexpected experimental consequences. We suggest that the system eventually evolves into a behavior similar to chaos.

  6. A new air-cooled argon/helium-compatible inductively coupled plasma torch.

    PubMed

    Miyahara, Hidekazu; Iwai, Takahiro; Kaburaki, Yuki; Kozuma, Tomokazu; Shigeta, Kaori; Okino, Akitoshi

    2014-01-01

    A new inductively coupled plasma (ICP) torch with an air-cooling system has been designed and developed for both argon and helium plasma. The same torch and impedance-matching network could be used to generate stable Ar- and He-ICP. The torch consists of three concentric quartz tubes. The carrier gas, plasma gas, and cooling gas flow through the intervals between each tube. In an experiment, it was found that Ar-ICP could form a stable plasma under the following conditions: RF power of 1 kW, plasma gas flow rate of 11 L min(-1), and cooling gas flow rate of 20 L min(-1). For He-ICP, an input RF power of 2 kW, which is two-times higher than that of a conventional He-ICP, could be constantly applied to the plasma with plasma gas and cooling gas flow rates of 15 and 20 L min(-1), respectively. Using this torch, it is possible to realize lower plasma gas consumption for Ar- and He-ICP and a high-power drive for He-ICP. It has been found that the air-cooling gas stabilizes the shape of the plasma due to the pressure difference between the cooling gas and the plasma gas.

  7. Influences of electrode configurations in dual capacitively coupled radio frequency glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Bora, B.; Soto, L.

    2015-03-01

    Capacitively coupled radio frequency (CCRF) glow discharge plasma is widely studied in the laboratory because of its simpler design and high efficiency for different material processing applications such as thin-film deposition, plasma etching, sputtering of insulating materials etc. A negative dc potential develops between the bulk plasma and the powered electrodes, which is termed as ‘self-bias’ in RF plasma. This self-bias is generated as a consequences of the geometrical asymmetry of the electrodes, which can be achieved by appropriately design the area of the powered and the grounded electrodes. However, independent control of the dc self-bias in single frequency CCRF plasma is not possible, since the changing in any operating parameters including geometrical asymmetry will also change the plasma parameters. A study on the dual frequency CCRF plasma could be useful in understanding the separate control of the dc self-bias and plasma density, which respectively determine the ion energy and ion flux. In this work, a dual frequency CCRF plasma have been studied on the basis on nonlinear global model to understand the influences of electrode sizes and proper optimization of the CCRF plasma for specific applications.

  8. Alfvén wave coupled with flow-driven fluid instability in interpenetrating plasmas

    SciTech Connect

    Vranjes, J.

    2015-05-15

    The Alfvén wave is analyzed in case of one quasineutral plasma propagating with some constant speed v{sub 0} through another static quasineutral plasma. A dispersion equation is derived describing the Alfvén wave coupled with the flow driven mode ω=kv{sub 0} and solutions are discussed analytically and numerically. The usual solutions for two oppositely propagating Alfvén waves are substantially modified due to the flowing plasma. More profound is modification of the solution propagating in the negative direction with respect to the magnetic field and the plasma flow. For a large enough flow speed (exceeding the Alfvén speed in the static plasma), this negative solution may become non-propagating, with frequency equal to zero. In this case, it represents a spatial variation of the electromagnetic field. For greater flow speed it becomes a forward mode, and it may merge with the positive one. This merging of the two modes represents the starting point for a flow-driven instability, with two complex-conjugate solutions. The Alfvén wave in interpenetrating plasmas is thus modified and coupled with the flow-driven mode and this coupled mode is shown to be growing when the flow speed is large enough. The energy for the instability is macroscopic kinetic energy of the flowing plasma. The dynamics of plasma particles caused by such a coupled wave still remains similar to the ordinary Alfvén wave. This means that well-known stochastic heating by the Alfvén wave may work, and this should additionally support the potential role of the Alfvén wave in the coronal heating.

  9. Modelling of an inductively coupled plasma torch with argon at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Bahouh, Hanene; Rebiai, Saida; Rochette, David; Vacher, Damien; Dudeck, Michel

    2014-05-01

    A fluid dynamic model is used to simulate the electromagnetic field, fluid flow and heat transfer in an inductively coupled plasma torch working at atmospheric pressure for argon plasma. The numerical simulation is carried out by using the finite element method based on COMSOL software. The two-dimensional profiles of the electric field, temperature, velocity and charged particle densities are demonstrated inside the discharge region. These numerical results are obtained for a fixed flow rate, frequency and electric power.

  10. Comprehensive Chemical Analysis of Metal Alloys by Means of Inductively Coupled Plasma Optical Emission Spectroscopy

    DTIC Science & Technology

    1985-10-01

    Multielement standard solutions were prepared from commercially available atomic absorbtion standard solutions or Spex Industries plasma-grade materials... SPECTROSCOPY W. E. Glad D"TIC LECTEfl Naval Ocean Systems Center scR. San Diego, California 92152-5000 Approved for public release; distribution unlimited 0...MEANS OF INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROSCOPY 12. PENSOIAF 111151 W.. la boron Stitaim tantlum nibim tn sten and EC zircNI in n n

  11. Energetic electron avalanches and mode transitions in planar inductively coupled radio-frequency driven plasmas operated in oxygen

    SciTech Connect

    Zaka-ul-Islam, M.; Niemi, K.; Gans, T.; O'Connell, D.

    2011-07-25

    Space and phase resolved optical emission spectroscopic measurements reveal that in certain parameter regimes, inductively coupled radio-frequency driven plasmas exhibit three distinct operation modes. At low powers, the plasma operates as an alpha-mode capacitively coupled plasma driven through the dynamics of the plasma boundary sheath potential in front of the antenna. At high powers, the plasma operates in inductive mode sustained through induced electric fields due to the time varying currents and associated magnetic fields from the antenna. At intermediate powers, close to the often observed capacitive to inductive (E-H) transition regime, energetic electron avalanches are identified to play a significant role in plasma sustainment, similar to gamma-mode capacitively coupled plasmas. These energetic electrons traverse the whole plasma gap, potentially influencing plasma surface interactions as exploited in technological applications.

  12. An experiment to measure the electron ion thermal equilibration rate in a strongly coupled plasma

    NASA Astrophysics Data System (ADS)

    Taccetti, J. M.; Shurter, R. P.; Roberts, J. P.; Benage, J. F.; Graden, B.; Haberle, B.; Murillo, M. S.; Vigil, B.; Wysocki, F. J.

    2006-04-01

    We present the most recent results from an experiment aimed at obtaining the temperature equilibration rate between ions and electrons in a strongly coupled plasma by directly measuring the temperature of each component. The plasma is formed by heating a sonic gas jet with a 10 ps laser pulse. The electrons are preferentially heated by the short pulse laser (we are aiming for Te ~ 100 eV), while the ions, after undergoing very rapid (sub-ps timescale) disorder-induced heating, should only reach a temperature of 10-15 eV. This results in a strongly coupled ion plasma with a Γii ~ 3-5. We plan to measure the electron and ion temperatures of the resulting plasma independently during and after heating, using collective Thomson scattering for electrons and a high-resolution x-ray spectrometer for the ions (measuring Doppler-broadened absorption lines). Theory indicates that the equilibration rate could be significantly lower than that given by the usual weakly coupled model (Landau-Spitzer) due to coupled collective modes present in the dense plasma.

  13. Equivalent circuit effects on mode transitions in H{sub 2} inductively coupled plasmas

    SciTech Connect

    Xu, Hui-Jing; Zhao, Shu-Xia Zhang, Yu-Ru; Gao, Fei; Li, Xue-Chun; Wang, You-Nian

    2015-04-15

    It is well known experimentally that the circuit matching network plays an important role in the mode transition behavior of inductively coupled plasmas. To date, however, there have been no reports of numerical models being used to study the role of the matching circuit in the transition process. In this paper, a new two-dimensional self-consistent fluid model that couples the components of an equivalent circuit module is developed to investigate the effects of the equivalent circuit on the mode transition characteristics of an inductively coupled, hydrogen plasma. The equivalent circuit consists of a current source, impedance matching network, reactor impedance, and plasma transferred impedance. The nonlinear coupling of the external circuit with the internal plasma is investigated by adjusting the matching capacitance at a fixed input current. The electron density and temperature as well as the electromagnetic fields all change suddenly, and the E to H mode transition occurs abruptly at a certain matching capacitance as the impedance matching of the external circuit is varied. We also analyze the fields and the plasma characteristics during the transition process, especially for the case of the capacitive E mode.

  14. Stable explicit coupling of the Yee scheme with a linear current model in fluctuating magnetized plasmas

    SciTech Connect

    Silva, Filipe da; Pinto, Martin Campos; Després, Bruno; Heuraux, Stéphane

    2015-08-15

    This work analyzes the stability of the Yee scheme for non-stationary Maxwell's equations coupled with a linear current model with density fluctuations. We show that the usual procedure may yield unstable scheme for physical situations that correspond to strongly magnetized plasmas in X-mode (TE) polarization. We propose to use first order clustered discretization of the vectorial product that gives back a stable coupling. We validate the schemes on some test cases representative of direct numerical simulations of X-mode in a magnetic fusion plasma including turbulence.

  15. Direct Observation of Mode-Coupling Instability in Two-Dimensional Plasma Crystals

    SciTech Connect

    Coueedel, L.; Nosenko, V.; Ivlev, A. V.; Zhdanov, S. K.; Thomas, H. M.; Morfill, G. E.

    2010-05-14

    Dedicated experiments on melting of two-dimensional plasma crystals were carried out. The melting was always accompanied by spontaneous growth of the particle kinetic energy, suggesting a universal plasma-driven mechanism underlying the process. By measuring three principal dust-lattice wave modes simultaneously, it is unambiguously demonstrated that the melting occurs due to the resonance coupling between two of the dust-lattice modes. The variation of the wave modes with the experimental conditions, including the emergence of the resonant (hybrid) branch, reveals exceptionally good agreement with the theory of mode-coupling instability.

  16. Visco-elastic fluid simulations of coherent structures in strongly coupled dusty plasma medium

    SciTech Connect

    Singh Dharodi, Vikram; Kumar Tiwari, Sanat; Das, Amita

    2014-07-15

    A generalized hydrodynamic model depicting the behaviour of visco-elastic fluids has often been invoked to explore the behaviour of a strongly coupled dusty plasma medium below their crystallization limit. The model has been successful in describing the collective normal modes of the strongly coupled dusty plasma medium observed experimentally. The paper focuses on the study of nonlinear dynamical characteristic features of this model. Specifically, the evolution of coherent vorticity patches is being investigated here within the framework of this model. A comparison with Newtonian fluids and molecular dynamics simulations treating the dust species interacting through the Yukawa potential has also been presented.

  17. Reduced electron temperature in a magnetized inductively-coupled plasma with internal coil

    SciTech Connect

    Arancibia Monreal, J.; Chabert, P.; Godyak, V.

    2013-10-15

    The effect of magnetic filtering on the electron energy distribution function is studied in an inductive discharge with internal coil coupling. The coil is placed inside the plasma and driven by a low-frequency power supply (5.8 MHz) which leads to a very high power transfer efficiency. A permanent dipole magnet may be placed inside the internal coil to produce a static magnetic field around 100 Gauss. The coil and the matching system are designed to minimize the capacitive coupling to the plasma. Capacitive coupling is quantified by measuring the radiofrequency (rf) plasma potential with a capacitive probe. Without the permanent magnet, the rf plasma potential is significantly smaller than the electron temperature. When the magnet is present, the rf plasma potential increases. The electron energy distribution function is measured as a function of space with and without the permanent magnet. When the magnet is present, electrons are cooled down to low temperature in the downstream region. This region of low electron temperature may be useful for plasma processing applications, as well as for efficient negative ion production.

  18. Characterization of Inductively Coupled Plasmas in High Power, High Pressure Regime

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Chieh; Kenney, Jason; Agarwal, Ankur; Nichols, Michael; Rogers, James; Rauf, Shahid

    2015-09-01

    Inductively coupled plasmas (ICP) are widely used in the microelectronic industry for thin film etching. ICPs have typically been operated at low gas pressures (<50 mTorr) and they have been well-characterized in this regime. Several applications requiring high etch rates (e.g., vertical NAND etch) have recently extended the use of ICPs to the high power (>4000 W) and high pressure (>100 mTorr) regime. ICP operation in this high-power, high-pressure regime imposes a tremendous challenge of achieving good plasma uniformity over large substrates. This necessitates a good theoretical understanding of the underlying physics, thorough experimental characterization, and more accurate numerical models for hardware design guidance. In this study, we will focus on the characterization of ICP in the high-power, high-pressure regime. Computational modeling is done using CRTRS, our in-house 2D/3D plasma model. The fluid plasma model is coupled to a circuit model to self-consistently account for the capacitive coupling from the coils that is expected to dominate in this operating regime. Properties of Ar plasma will be discussed and compared with experiments. The impact of critical operating parameters such as ICP power, pressure, flow rate, and current ratio (in multi-coil antenna structures) on plasma characteristics will be examined. Results in relevant processing gases will also be discussed.

  19. Reduced electron temperature in a magnetized inductively-coupled plasma with internal coil

    NASA Astrophysics Data System (ADS)

    Arancibia Monreal, J.; Chabert, P.; Godyak, V.

    2013-10-01

    The effect of magnetic filtering on the electron energy distribution function is studied in an inductive discharge with internal coil coupling. The coil is placed inside the plasma and driven by a low-frequency power supply (5.8 MHz) which leads to a very high power transfer efficiency. A permanent dipole magnet may be placed inside the internal coil to produce a static magnetic field around 100 Gauss. The coil and the matching system are designed to minimize the capacitive coupling to the plasma. Capacitive coupling is quantified by measuring the radiofrequency (rf) plasma potential with a capacitive probe. Without the permanent magnet, the rf plasma potential is significantly smaller than the electron temperature. When the magnet is present, the rf plasma potential increases. The electron energy distribution function is measured as a function of space with and without the permanent magnet. When the magnet is present, electrons are cooled down to low temperature in the downstream region. This region of low electron temperature may be useful for plasma processing applications, as well as for efficient negative ion production.

  20. ICRH antenna coupling physics and optimum plasma edge density profile. Application to ITER

    NASA Astrophysics Data System (ADS)

    Messiaen, A.; Weynants, R.

    2011-08-01

    The performance of an ICRH system depends on the coupling capabilities of the antenna to the inhomogeneous plasma profile in front of it. The aim of this study is to understand the key physics phenomena contributing to the coupling. It is shown that the following plasma density profile characteristics are decisive: (i) distance between the antenna and the wave cutoff density, (ii) position of an optimum density with respect to the cutoff one and (iii) the density gradient leading from this optimum density to the plasma bulk. At each step of the analysis approximate relations are derived and the loading due to the plasma is compared with that of an isotropic dielectric medium in view of the application for modelling or dummy load testing. Examples are taken starting from the case of the projected ITER antenna array with its different phasing cases in front of the plasma edge profile used in the conceptual design phase. It is shown that, for the same antenna-cutoff distance, slight profile modifications can lead to substantial coupling and therefore power capability variations. Stronger profile modifications and some critically shaped resonant edge profiles are also analysed. The usefulness of a dielectric medium to simulate plasma loading is discussed in an appendix.

  1. A unified model of coupled arc plasma and weld pool for double electrodes TIG welding

    NASA Astrophysics Data System (ADS)

    Wang, Xinxin; Fan, Ding; Huang, Jiankang; Huang, Yong

    2014-07-01

    A three-dimensional model containing tungsten electrodes, arc plasma and a weld pool is presented for double electrodes tungsten inert gas welding. The model is validated by available experimental data. The distributions of temperature, velocity and pressure of the coupled arc plasma are investigated. The current density, heat flux and shear stress over the weld pool are highlighted. The weld pool dynamic is described by taking into account buoyance, Lorentz force, surface tension and plasma drag force. The turbulent effect in the weld pool is also considered. It is found that the temperature and velocity distributions of the coupled arc are not rotationally symmetrical. A similar property is also shown by the arc pressure, current density and heat flux at the anode surface. The surface tension gradient is much larger than the plasma drag force and dominates the convective pattern in the weld pool, thus determining the weld penetration. The anodic heat flux and plasma drag force, as well as the surface tension gradient over the weld pool, determine the weld shape and size. In addition, provided the welding current through one electrode increases and that through the other decreases, keeping the total current unchanged, the coupled arc behaviour and weld pool dynamic change significantly, while the weld shape and size show little change. The results demonstrate the necessity of a unified model in the study of the arc plasma and weld pool.

  2. Numerical and Experimental Investigation on the Attenuation of Electromagnetic Waves in Unmagnetized Plasmas Using Inductively Coupled Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Lin, Min; Xu, Haojun; Wei, Xiaolong; Liang, Hua; Song, Huimin; Sun, Quan; Zhang, Yanhua

    2015-10-01

    The attenuation of electromagnetic (EM) waves in unmagnetized plasma generated by an inductively coupled plasma (ICP) actuator has been investigated both theoretically and experimentally. A numerical study is conducted to investigate the propagation of EM waves in multilayer plasma structures which cover a square flat plate. Experimentally, an ICP actuator with dimensions of 20 cm×20 cm×4 cm is designed to produce a steady plasma slab. The attenuation of EM waves in the plasma generated by the ICP actuator is measured by a reflectivity arch test method at incident waves of 2.3 GHz and 10.1 GHz, respectively. A contrastive analysis of calculated and measured results of these incident wave frequencies is presented, which suggests that the experiment accords well with our theory. As expected, the plasma slab generated by the ICP actuator can effectively attenuate the EM waves, which may have great potential application prospects in aircraft stealth. supported by National Natural Science Foundation of China (Nos. 51276197, 11472306 and 11402301)

  3. Investigation of large-area multicoil inductively coupled plasma sources using three-dimensional fluid model

    NASA Astrophysics Data System (ADS)

    Brcka, Jozef

    2016-07-01

    A multi inductively coupled plasma (ICP) system can be used to maintain the plasma uniformity and increase the area processed by a high-density plasma. This article presents a source in two different configurations. The distributed planar multi ICP (DM-ICP) source comprises individual ICP sources that are not overlapped and produce plasma independently. Mutual coupling of the ICPs may affect the distribution of the produced plasma. The integrated multicoil ICP (IMC-ICP) source consists of four low-inductance ICP antennas that are superimposed in an azimuthal manner. The identical geometry of the ICP coils was assumed in this work. Both configurations have highly asymmetric components. A three-dimensional (3D) plasma model of the multicoil ICP configurations with asymmetric features is used to investigate the plasma characteristics in a large chamber and the operation of the sources in inert and reactive gases. The feasibility of the computational calculation, the speed, and the computational resources of the coupled multiphysics solver are investigated in the framework of a large realistic geometry and complex reaction processes. It was determined that additional variables can be used to control large-area plasmas. Both configurations can form a plasma, that azimuthally moves in a controlled manner, the so-called “sweeping mode” (SM) or “polyphase mode” (PPM), and thus they have the potential for large-area and high-density plasma applications. The operation in the azimuthal mode has the potential to adjust the plasma distribution, the reaction chemistry, and increase or modulate the production of the radicals. The intrinsic asymmetry of the individual coils and their combined operation were investigated within a source assembly primarily in argon and CO gases. Limited investigations were also performed on operation in CH4 gas. The plasma parameters and the resulting chemistry are affected by the geometrical relation between individual antennas. The aim of

  4. A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas

    DTIC Science & Technology

    2016-02-29

    conditions over a broad spectrum of operating conditions demonstrate the robustness of the proposed coupled numerical method. The analysis of chemical...by means of an implicit Finite Volume method. The results obtained in both LTE and NLTE conditions over a broad spectrum of operating conditions...flow-field and electromagnetic phenomena inside an ICP torch requires, in theory, the coupled solution of the Navier-Stokes and the Maxwell equations

  5. Ionized Magnetron Sputtering with a Coupled DC and Microwave Plasma

    NASA Astrophysics Data System (ADS)

    Hayden, D. B.; Green, K. M.; Juliano, D. R.; Ruzic, D. N.; Weiss, C. A.; Lantsman, A.; Ishii, J.

    1996-10-01

    A DC magnetron sputtering system is enhanced via an antenna microwave source. The ability of the microwaves to ionize the metal atoms from the aluminum target though electron impact and Penning ionization is studied as a function of microwave power, magnetron power, and pressure. A bias in the tens of volts (negative) is applied to the substrate and sample. This creates an electric field between the plasma and the substrate which is designed to draw the metal ions into the sample orthogonally for filling increased aspect ratio trenches. A quartz crystal oscillator is placed behind a gridded energy analyzer and embedded in the substrate. It determines the ion-to-neutral ratio and the deposition rate, and the gridded energy analyzer determines the energy spectrum of the ions, the ion current density, and the uniformity. These quantities are compared to the results of a computer simulation.

  6. Temperature dependence of inductively coupled plasma assisted growth of TiN thin films.

    SciTech Connect

    Meng, W. J.; Curtis, T. J.; Rehn, L. E.; Baldo, P. M.; Materials Science Division; Louisiana State Univ.

    1999-11-01

    The use of low pressure high density plasmas to assist the synthesis of ceramic thin film materials is in its infancy. Using an inductively coupled plasma assisted magnetron sputtering system, we examine the dependence of plasma-assisted growth of TiN thin films on growth temperature at different ratios of ion flux to neutral atom flux. Our results indicate that a temperature independent densification of TiN films occurs above a certain ion to neutral atom flux ratio. As an example of this temperature independent densification, we demonstrate the formation of dense B1 TiN crystalline thin films at growth temperatures down to {approx}100 K.

  7. Pedestal Fueling Simulations with a Coupled Kinetic-kinetic Plasma-neutral Transport Code

    SciTech Connect

    D.P. Stotler, C.S. Chang, S.H. Ku, J. Lang and G.Y. Park

    2012-08-29

    A Monte Carlo neutral transport routine, based on DEGAS2, has been coupled to the guiding center ion-electron-neutral neoclassical PIC code XGC0 to provide a realistic treatment of neutral atoms and molecules in the tokamak edge plasma. The DEGAS2 routine allows detailed atomic physics and plasma-material interaction processes to be incorporated into these simulations. The spatial pro le of the neutral particle source used in the DEGAS2 routine is determined from the uxes of XGC0 ions to the material surfaces. The kinetic-kinetic plasma-neutral transport capability is demonstrated with example pedestal fueling simulations.

  8. Energy Conservation Tests of a Coupled Kinetic-kinetic Plasma-neutral Transport Code

    SciTech Connect

    Stotler, D. P.; Chang, C. S.; Ku, S. H.; Lang, J.; Park, G.

    2012-08-29

    A Monte Carlo neutral transport routine, based on DEGAS2, has been coupled to the guiding center ion-electron-neutral neoclassical PIC code XGC0 to provide a realistic treatment of neutral atoms and molecules in the tokamak edge plasma. The DEGAS2 routine allows detailed atomic physics and plasma-material interaction processes to be incorporated into these simulations. The spatial pro le of the neutral particle source used in the DEGAS2 routine is determined from the uxes of XGC0 ions to the material surfaces. The kinetic-kinetic plasma-neutral transport capability is demonstrated with example pedestal fueling simulations.

  9. Development of very small-diameter, inductively coupled magnetized plasma device.

    PubMed

    Kuwahara, D; Mishio, A; Nakagawa, T; Shinohara, S

    2013-10-01

    In order to miniaturize a high-density, inductively coupled magnetized plasma or helicon plasma to be applied to, e.g., an industrial application and an electric propulsion field, small helicon device has been developed. The specifications of this device along with the experimental results are described. We have succeeded in generating high-density (~10(19) m(-3)) plasmas using quartz tubes with very small diameters of 10 and 20 mm, with a radio frequency power ~1200 and 700 W, respectively, in the presence of the magnetic field less than 1 kG.

  10. Theoretical investigation of phase-controlled bias effect in capacitively coupled plasma discharges

    SciTech Connect

    Kwon, Deuk-Chul; Yoon, Jung-Sik

    2011-07-15

    We theoretically investigated the effect of phase difference between powered electrodes in capacitively coupled plasma (CCP) discharges. Previous experimental result has shown that the plasma potential could be controlled by using a phase-shift controller in CCP discharges. In this work, based on the previously developed radio frequency sheath models, we developed a circuit model to self-consistently determine the bias voltage from the plasma parameters. Results show that the present theoretical model explains the experimental results quite well and there is an optimum value of the phase difference for which the V{sub dc}/V{sub pp} ratio becomes a minimum.

  11. The analysis of conductive solid samples by r.f. capacitively coupled plasma at atmospheric pressure.

    PubMed

    Anghel, S D; Frentiu, T; Rusu, A M; Bese, L; Cordos, E A

    1996-06-01

    A radiofrequency capacitively coupled plasma (rf CCP) with tip-ring electrode geometry has been used for the analysis of Al, Co, Cr, Cu, Mn, Mo, Ni, and V in low and medium alloyed steel. The sample is used as one of the electrodes of the plasma torch. The influence of plasma power, argon flow rate and distance between the electrodes on the analytical signals has been studied. The limits of detection are in the range of 0.001 to 0.048%. The dynamic range is three orders of magnitude.

  12. Role of hydrogen in evolution of plasma parameters and dust growth in capacitively coupled dusty plasmas

    SciTech Connect

    Chai, K. B.; Choe, Wonho; Seon, C. R.; Chung, C. W.

    2010-11-15

    The temporal behavior of naturally produced dust parameters (radius and density) and plasma parameters (electron temperature and ion flux) was investigated in radio frequency SiH{sub 4}/H{sub 2}/Ar plasmas. As a result, the electron temperature and ion flux were shown to be strongly correlated with the three-step dust growth pattern. In addition, the generation of dust particles was suppressed by mixing more hydrogen gas due to the plasma chemistry, and consequently, the dust growth rate in the molecular accretion growth, which is known to be proportional to the growth rate of thin film deposition, increased.

  13. Styrene and methyl methacrylate copolymer synthesized by RF inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Li, Z.; Gillon, X.; Diallo, M.; Houssiau, L.; Pireaux, J.-J.

    2011-01-01

    A series of random copolymers of styrene and methyl methacrylate was prepared on a silicon substrate by RF pulsed inductively coupled plasma. The plasma gas phase was investigated by optical emission spectroscopy (OES). The physico-chemical characteristics of the deposited copolymer films were analyzed by several surface techniques: X-ray photoelectron spectroscopy (XPS), Fourier-Transform infrared absorption (FT-IR), Time-of-flight secondary ion mass spectrometry (ToF-SIMS), etc. OES of the plasma and FT-IR spectra of the films are predictive: plasma emitting a higher relative benzyl radical signal results in the deposition of a more aromatic plasma polymer. The functional thin films can be deposited by selection of the co-monomers.

  14. Langmuir probe study of an inductively coupled magnetic-pole-enhanced helium plasma

    NASA Astrophysics Data System (ADS)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Naeem, M.; Zaka-ul-Islam, M.; Zakaullah, M.

    2017-03-01

    This study reports the effects of RF power and filling gas pressure variation on the plasma parameters, including the electron number density n e , electron temperature T e , plasma potential V p , skin depth δ, and electron energy probability functions (EEPFs) in a low-pressure inductively coupled helium plasma source with magnetic pole enhancement. An RF compensated Langmuir probe is used to measure these plasma parameters. It is observed that the electron number density increases with both the RF power and the filling gas pressure. Conversely, the electron temperature decreases with increasing RF power and gas pressure. It is also noted that, at low RF powers and gas pressures, the EEPFs are non-Maxwellian, while at RF powers of ≥50 W, they evolve into a Maxwellian distribution. The dependences of the skin depth and plasma potential on the RF power are also studied and show a decreasing trend.

  15. Broadband microwave absorption and standing wave effect in helium capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yachun; He, Xiang; Chen, Jianping; Chen, Li; Zhang, Hongchao; Ni, Xiaowu; Lu, Jian; Shen, Zhonghua

    2017-08-01

    The broadband microwave absorption of a large volume helium plasma, which is generated by two parallel rectangular plates based on the principle of capacitively coupled plasma (CCP) is developed in this paper. The transmission attenuation is simulated by the combination of the time-dependent fluid model and dispersion equation, and measured by a high dynamic range measurement system in a frequency range of 1 -12 GHz . The results show that the plasma can absorb microwave energy efficiently, especially in the frequency range of 1 -5 GHz , where the transmission attenuation is more than -5 dB . The attenuation increases with gas pressures and applied voltages. Besides, the standing wave effect in plasma can increase the microwave absorption effectively. The numerical and experimental results have a qualitative agreement, and these characteristics suggest that the helium CCP has tremendous potential to be applied in plasma stealth.

  16. Inductively-Coupled RF Powered O2 Plasma as a Sterilization Source

    NASA Technical Reports Server (NTRS)

    Sharma, S. P.; Rao, M. V. V. S.; Cruden, B. A.; Meyyappan, M.; Mogul, R.; Khare, B.; Chan, S. L.; Arnold, James O. (Technical Monitor)

    2001-01-01

    Low-temperature or cold plasmas have been shown to be effective for the sterilization of sensitive medical devices and electronic equipment. Low-temperature plasma sterilization procedures possess certain advantages over other protocols such as ethylene oxide, gamma radiation, and heat due to the use of inexpensive reagents, the insignificant environmental impacts and the low energy requirements. In addition, plasmas may also be more efficacious in the removal of robust microorganisms due to their higher chemical reactivity. Together, these attributes render cold plasma sterilization as ideal for the surface decontamination requirements for NASA Planetary Protection. Hence, the work described in this study involves the construction, characterization, and application of an inductively-coupled, RF powered oxygen (O2) plasma.

  17. Observation of a strong-coupling effect on electron-ion collisions in ultracold plasmas

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Ting; Witte, Craig; Roberts, Jacob L.

    2017-07-01

    Ultracold plasmas (UCPs) provide a well-controlled system for studying multiple aspects in plasma physics that include collisions and strong-coupling effects. By applying a short electric field pulse to an UCP, a plasma electron center-of-mass oscillation can be initiated. For accessible parameter ranges, the damping rate of this oscillation is determined by the electron-ion collision rate. We performed measurements of the oscillation damping rate with such parameters and compared the measured rates to both a molecular dynamics (MD) simulation that includes strong-coupling effects and a Monte Carlo binary collision simulation designed to predict the damping rate including only weak-coupling considerations. We found agreement between the experimentally measured damping rate and the MD result. This agreement did require including the influence of a previously unreported UCP heating mechanism whereby the presence of a dc electric field during ionization increased the electron temperature, but estimations and simulations indicate that such a heating mechanism should be present for our parameters. The measured damping rate at our coldest electron temperature conditions was much faster than the weak-coupling prediction obtained from the Monte Carlo binary collision simulation, which indicates the presence of a significant strong-coupling influence. The density averaged electron strong-coupling parameter Γ measured at our coldest electron temperature conditions was 0.35(8).

  18. Nonrelativistic structure calculations of two-electron ions in a strongly coupled plasma environment

    SciTech Connect

    Bhattacharyya, S.; Saha, J. K.; Mukherjee, T. K.

    2015-04-01

    In this work, the controversy between the interpretations of recent measurements on dense aluminum plasma created with the Linac coherent light source (LCLS) x-ray free electron laser (FEL) and the Orion laser has been addressed. In both kinds of experiments, heliumlike and hydrogenlike spectral lines are used for plasma diagnostics. However, there exist no precise theoretical calculations for He-like ions within a dense plasma environment. The strong need for an accurate theoretical estimate for spectral properties of He-like ions in a strongly coupled plasma environment leads us to perform ab initio calculations in the framework of the Rayleigh-Ritz variation principle in Hylleraas coordinates where an ion-sphere potential is used. An approach to resolve the long-drawn problem of numerical instability for evaluating two-electron integrals with an extended basis inside a finite domain is presented here. The present values of electron densities corresponding to the disappearance of different spectral lines obtained within the framework of an ion-sphere potential show excellent agreement with Orion laser experiments in Al plasma and with recent theories. Moreover, this method is extended to predict the critical plasma densities at which the spectral lines of H-like and He-like carbon and argon ions disappear. Incidental degeneracy and level-crossing phenomena are being reported for two-electron ions embedded in strongly coupled plasma. Thermodynamic pressure experienced by the ions in their respective ground states inside the ion spheres is also reported.

  19. An argon-nitrogen-hydrogen mixed-gas plasma as a robust ionization source for inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Makonnen, Yoseif; Beauchemin, Diane

    2014-09-01

    Multivariate optimization of an argon-nitrogen-hydrogen mixed-gas plasma for minimum matrix effects, while maintaining analyte sensitivity as much as possible, was carried out in inductively coupled plasma mass spectrometry. In the presence of 0.1 M Na, the 33.9 ± 3.9% (n = 13 elements) analyte signal suppression on average observed in an all-argon plasma was alleviated with the optimized mixed-gas plasma, the average being - 4.0 ± 8.8%, with enhancement in several cases. An addition of 2.3% v/v N2 in the outer plasma gas, and 0.50% v/v H2 to the central channel, as a sheath around the nebulizer gas flow, was sufficient for this drastic increase in robustness. It also reduced the background from ArO+ and Ar2+ as well as oxide levels by over an order of magnitude. On the other hand, the background from NO+ and ArN+ increased by up to an order of magnitude while the levels of doubly-charged ions increased to 7% (versus 2.7% in an argon plasma optimized for sensitivity). Furthermore, detection limits were generally degraded by 5 to 15 fold when using the mixed-gas plasma versus the argon plasma for matrix-free solution (although they were better for several elements in 0.1 M Na). Nonetheless, the drastically increased robustness allowed the direct quantitative multielement analysis of certified ore reference materials, as well as the determination of Mo and Cd in seawater, without using any matrix-matching or internal standardization.

  20. Effects of interelectrode gap on high frequency and very high frequency capacitively coupled plasmas

    SciTech Connect

    Bera, Kallol; Rauf, Shahid; Ramaswamy, Kartik; Collins, Ken

    2009-07-15

    Capacitively coupled plasma (CCP) discharges using high frequency (HF) and very high frequency (VHF) sources are widely used for dielectric etching in the semiconductor industry. A two-dimensional fluid plasma model is used to investigate the effects of interelectrode gap on plasma spatial characteristics of both HF and VHF CCPs. The plasma model includes the full set of Maxwell's equations in their potential formulation. The peak in plasma density is close to the electrode edge at 13.5 MHz for a small interelectrode gap. This is due to electric field enhancement at the electrode edge. As the gap is increased, the plasma produced at the electrode edge diffuses to the chamber center and the plasma becomes more uniform. At 180 MHz, where electromagnetic standing wave effects are strong, the plasma density peaks at the chamber center at large interelectrode gap. As the interelectrode gap is decreased, the electron density increases near the electrode edge due to inductive heating and electrostatic electron heating, which makes the plasma more uniform in the interelectrode region.

  1. Residues of correlators in the strongly coupled N=4 plasma

    SciTech Connect

    Amado, Irene; Landsteiner, Karl; Montero, Sergio; Hoyos, Carlos

    2008-03-15

    Quasinormal modes of asymptotically AdS black holes can be interpreted as poles of retarded correlators in the dual gauge theory. To determine the response of the system to small external perturbations it is not enough to know the location of the poles: one also needs to know the residues. We compute them for R-charge currents and find that they are complex except for the hydrodynamic mode, whose residue is purely imaginary. For different quasinormal modes the residue grows with momentum q, whereas for the hydrodynamic mode it behaves as a damped oscillation with distinct zeroes at finite q. Similar to collective excitations at weak coupling the hydrodynamic mode decouples at short wavelengths. Knowledge of the residues allows as well to define the time scale {tau}{sub H} from when on the system enters the hydrodynamic regime, restricting the validity of hydrodynamic simulations to times t>{tau}{sub H}.

  2. Speciation of trace elements in human serum by micro anion exchange chromatography coupled with inductively coupled plasma mass spectrometry.

    PubMed

    Malavolta, Marco; Piacenza, Francesco; Basso, Andrea; Giacconi, Robertina; Costarelli, Laura; Pierpaoli, Sara; Mocchegiani, Eugenio

    2012-02-01

    Speciation analysis of essential trace elements in human serum provides important information on nutritional status and homeostatic mechanisms regulating transport processes, acute phase reactions, and protection against oxidative damage. Anion exchange high-performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectrometry (ICP-MS) has proved to be a useful tool in speciation. Here we describe a fast method that can be applied to carry out the speciation of Fe, Cu, Zn, and Se in as little as 1 microl [corrected] of serum. The method employs monolithic anion exchange micro columns installed on a tandem HPLC system coupled on-line with an ICP-MS detector. The chromatographic separation is similar to those reported previously but with considerable gain in terms of time and sample requirement. Reproducibility is acceptable for most species. Using our method, we were able to find species-specific differences between different commercially available trace element reference materials. Because the method chosen to collect blood might interfere with speciation, the proposed methodology was used to compare heparinized plasma, ethylenediaminetetraacetic acid (EDTA) plasma, and serum from adult healthy volunteers. As expected, EDTA strongly affects speciation analysis (especially for Fe and Zn), whereas changes due to the use of lithium-heparin (Li-He) as anticoagulant appear to be minimized.

  3. Electron kinetics in capacitively coupled plasmas modulated by electron injection

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Peng, Yanli; Innocenti, Maria Elena; Jiang, Wei; Wang, Hong-yu; Lapenta, Giovanni

    2017-09-01

    The controlling effect of an electron injection on the electron energy distribution function (EEDF) and on the energetic electron flux, in a capacitive radio-frequency argon plasma, is studied using a one-dimensional particle-in-cell/Monte Carlo collisions model. The input power of the electron beam is as small as several tens of Watts with laboratory achievable emission currents and energies. With the electron injection, the electron temperature decreases but with a significant high energy tail. The electron density, electron temperature in the sheath, and electron heating rate increase with the increasing emission energy. This is attributed to the extra heating of the energetic electrons in the EEDF tail. The non-equilibrium EEDF is obtained for strong non-local distributions of the electric field, electron heating rate, excitation, and ionization rate, indicating the discharge has transited from a volume heating (α-mode dominated) into a sheath heating (γ-mode dominated) type. In addition, the electron injection not only modifies the self-bias voltage, but also enhances the electron flux that can reach the electrodes. Moreover, the relative population of energetic electrons significantly increases with the electron injection compared to that without the electron injection, relevant for modifying the gas and surface chemistry reactions.

  4. Induced magnetic-field effects in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Cohen, Ronald H.; Rognlien, Thomas D.

    1996-05-01

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday's law. It was previously shown that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here the electron density calculation is extended to include both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. The potential required to establish a constant electron density is calculated and compared with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest.

  5. Induced magnetic-field effects in inductively coupled plasmas

    SciTech Connect

    Cohen, R.H.; Rognlien, T.D.

    1995-11-04

    In inductive plasma sources, the rapid spatial decay of the electric field arising from the skin effect produces a large radio frequency (RF) magnetic field via Faraday`s law. We previously determined that this magnetic field leads to a reduction of the electron density in the skin region, as well as a reduction in the collisionless heating rate. The electron deficit leads to the formation of an electrostatic potential which pulls electrons in to restore quasineutrality. Here we calculate the electron density including both the induced and electrostatic fields. If the wave frequency is not too low, the ions respond only to the averaged fields, and hence the electrostatic field is oscillatory, predominantly at the second harmonic of the applied field. We calculate the potential required to establish a constant electron density, and compare with numerical orbit-code calculations. For times short compared to ion transit times, the quasineutral density is just the initial ion density. For timescales long enough that the ions can relax, the density profile can be found from the solution of fluid equations with an effective (ponderomotive-like) potential added. Although the time-varying electrostatic potential is an extra source of heating, the net effect of the induced magnetic and electrostatic fields through trapping, early turning, and direct heating is a significant reduction in collisionless heating for parameters of interest.

  6. Determination of Arsenic in Sinus Wash and Tap Water by Inductively Coupled Plasma-Mass Spectrometry

    ERIC Educational Resources Information Center

    Donnell, Anna M.; Nahan, Keaton; Holloway, Dawone; Vonderheide, Anne P.

    2016-01-01

    Arsenic is a toxic element to which humans are primarily exposed through food and water; it occurs as a result of human activities and naturally from the earth's crust. An experiment was developed for a senior level analytical laboratory utilizing an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) for the analysis of arsenic in household…

  7. ULTRASONIC NEBULIZATION AND ARSENIC VALENCE STATE CONSIDERATIONS PRIOR TO DETERMINATION VIA INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    EPA Science Inventory

    An ultrasonic nebulizer (USN) was utilized as a sample introduction device for an inductively coupled plasma mass spectrometer in an attempt to increase the sensitivity for As. The USN produced a valence state response difference for As. The As response was suppressed approximate...

  8. Determination of Arsenic in Sinus Wash and Tap Water by Inductively Coupled Plasma-Mass Spectrometry

    ERIC Educational Resources Information Center

    Donnell, Anna M.; Nahan, Keaton; Holloway, Dawone; Vonderheide, Anne P.

    2016-01-01

    Arsenic is a toxic element to which humans are primarily exposed through food and water; it occurs as a result of human activities and naturally from the earth's crust. An experiment was developed for a senior level analytical laboratory utilizing an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) for the analysis of arsenic in household…

  9. In situ calibration of inductively coupled plasma-atomic emission and mass spectroscopy

    DOEpatents

    Braymen, Steven D.

    1996-06-11

    A method and apparatus for in situ addition calibration of an inductively coupled plasma atomic emission spectrometer or mass spectrometer using a precision gas metering valve to introduce a volatile calibration gas of an element of interest directly into an aerosol particle stream. The present situ calibration technique is suitable for various remote, on-site sampling systems such as laser ablation or nebulization.

  10. ULTRASONIC NEBULIZATION AND ARSENIC VALENCE STATE CONSIDERATIONS PRIOR TO DETERMINATION VIA INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    EPA Science Inventory

    An ultrasonic nebulizer (USN) was utilized as a sample introduction device for an inductively coupled plasma mass spectrometer in an attempt to increase the sensitivity for As. The USN produced a valence state response difference for As. The As response was suppressed approximate...

  11. The analysis of some evidential materials by inductively coupled plasma-optical emission spectrometry.

    PubMed

    Carpenter, R C

    1985-03-01

    Inductively coupled plasma-optical emission spectrometry (ICP-OES) is under evaluation at the Central Research Establishment for the analysis of evidential materials. The analysis of standard reference materials has demonstrated that quantitative multi-element data can be obtained from small samples of a variety of materials. The results of some determinations carried out in support of casework investigations are reported.

  12. Efficient Coupling of 527 nm Laser Beam Power to a Long Scalelength Plasma

    SciTech Connect

    Moody, J D; Divol, L; Glenzer, S H; MacKinnon, A J; Froula, D H; Gregori, G; Kruer, W L; Meezan, N B; Suter, L J; Williams, E A; Bahr, R; Seka, W

    2005-08-24

    We experimentally demonstrate that application of laser smoothing schemes including smoothing by spectral dispersion (SSD) and polarization smoothing (PS) increases the intensity range for efficient coupling of frequency doubled (527 nm) laser light to a long scalelength plasma with n{sub e}/n{sub cr} = 0.14 and T{sub e} = 2 keV.

  13. Discontinuity of mode transition and hysteresis in hydrogen inductively coupled plasma via a fluid model

    NASA Astrophysics Data System (ADS)

    Xu, Hui-Jing; Zhao, Shu-Xia; Fei, Gao; Yu-Ru, Zhang; Xue-Chun, Li; You-Nian, Wang

    2015-11-01

    A new type of two-dimensional self-consistent fluid model that couples an equivalent circuit module is used to investigate the mode transition characteristics and hysteresis in hydrogen inductively coupled plasmas at different pressures, by varying the series capacitance of the matching box. The variations of the electron density, temperature, and the circuit electrical properties are presented. As cycling the matching capacitance, at high pressure both the discontinuity and hysteresis appear for the plasma parameters and the transferred impedances of both the inductive and capacitive discharge components, while at low pressure only the discontinuity is seen. The simulations predict that the sheath plays a determinative role on the presence of discontinuity and hysteresis at high pressure, by influencing the inductive coupling efficiency of applied power. Moreover, the values of the plasma transferred impedances at different pressures are compared, and the larger plasma inductance at low pressure due to less collision frequency, as analyzed, is the reason why the hysteresis is not seen at low pressure, even with a wider sheath. Besides, the behaviors of the coil voltage and current parameters during the mode transitions are investigated. They both increase (decrease) at the E to H (H to E) mode transition, indicating an improved (worsened) inductive power coupling efficiency. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175034, 11205025, 11305023, and 11075029).

  14. Atlas of atomic spectral lines of plutonium emitted by an inductively coupled plasma

    SciTech Connect

    Edelson, M.C.; DeKalb, E.L.; Winge, R.K.; Fassel, V.A.

    1986-09-01

    Optical emission spectra from high-purity Pu-242 were generated with a glovebox-enclosed inductively coupled plasma (ICP) source. Spectra covering the 2280 to 7008 Angstrom wavelength range are presented along with general commentary on ICP-Pu spectroscopy.

  15. DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

  16. Atlas of atomic spectral lines of neptunium emitted by an inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Dekalb, E. L.; Edelson, M. C.

    1987-08-01

    Optical emission spectra from high-purity Np-237 were generated with a glovebox-enclosed inductively coupled plasma (ICP) source. Spectra covering the 230 to 700 nm wavelength range are presented along with general commentary on the methodology used in collecting the data.

  17. Diagnostics and controls for spatiotemporal couplings for laser-plasma accelerator drivers

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Vincenti, H.; Mittelberger, D. E.; Mao, H.-S.; Gonsalves, A. J.; Toth, C.; Leemans, W. P.

    2017-03-01

    Diagnostic and control of spatiotemporal couplings for laser-plasma acceleration drive lasers are discussed. Near-field angular dispersion and spatial chirp were measured by GRENOUILLE. The calculation of the pulse front tilt evolution is presented, and it is shown that the pulse front angle near focus can be controlled within 5 mrad, and finely tuned through temporal chirp.

  18. [CPFA (coupled plasma filtration absorption) treatment of septic shock. A retrospective study of nine patients].

    PubMed

    Maruccio, Gianfranco; Montanaro, Alessio; Schiavone, Palmira; Fumarola, Martino; Flores, Antonio; Strippoli, Paolo; Caretto, Vincenzo; Paladini, Daniele; Ramunni, Alfonso

    2012-01-01

    Coupled plasma filtration absorption (CPFA) can increase blood pressure in septic shock and reduce fever during and after treatment. It is not able to stop the activation of intravascular coagulation and does not reduce the need for dialysis or the overall mortality.

  19. DETERMINATION OF BROMATE IN DRINKING WATERS BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection by-product in drinking water, formed during the ozonation of source water containing bromide. An inductively coupled plasma mass spectrometer is combined with an ion chromatograph for the analysis of bromate in drinking waters. Three chromatographic colu...

  20. Characteristic temperatures and electron number densities in an R.F. capacitively coupled plasma.

    PubMed

    Anghel, S D; Frentiu, T; Darvasi, E; Rusu, A M; Simon, A; Cordos, E A

    1996-06-01

    The excitation temperatures of Ar and Fe, the ionization temperatures of Ar and Ca and the electron number densities have been determined for a radiofrequency capacitively coupled plasma in the tip-ring electrode geometry. The temperatures and the electron number densities possess their maximum value close to the electrodes.

  1. Capacitively Coupled Radio Frequency Discharge Plasmas In Hydrogen: Particle Modeling and Negative Ion Kinetics

    SciTech Connect

    Diomede, P.; Longo, S.; Capitelli, M.

    2005-05-16

    We present a 1D(r)2D(v) particle code for capacitively coupled radio frequency discharge plasmas in hydrogen, which includes a rigorous kinetic modeling of ion transport and several solutions to speed up the convergence. In a test case the effect of surface atom recombination and molecule vibrational deactivation on H- concentration is investigated.

  2. Study of the Ionization Dynamics and Equation of State of a Strongly Coupled Plasma

    SciTech Connect

    Shepherd, R; Audebert, P; Geindre, J P; Iglesias, C; Foord, M; Rogers, F; Gauthier, J C; Springer, P

    2003-02-06

    Preliminary experiments to study the ionization dynamics and equation of state of a strongly coupled plasma have been performed at the LLNL COMET laser facility. In these experiment, a 1.0 J, 500 fs, 532 nm laser was used to create a uniform, warm dense plasma.The primary diagnostic, Fourier Domain Interferometry (FDI), was used to provide information about the position of the critical density of the target and thus the expansion hydrodynamics, laying the ground work for the plasma characterization. The plasmas were determined to be strongly coupled. In addition work was performed characterizing the back-lighter. A von Hamos spectrograph coupled to a 500 fs X-ray streak camera (TREX-VHS) developed at LLNL was used for these measurements. This diagnostic combines high collection efficiency ({approx} 10{sup -4} steradians) with fast temporal response ({approx} 500 fs), allowing resolution of extremely transient spectral variations. The TREX-VHS will be used to determine the time history, intensity, and spectral content of the back-lighter resulting in absorption measurements that provide insight into bound states in strongly coupled conditions.

  3. Inductively coupled plasma-atomic emission spectroscopy: The determination of trace impurities in uranium hexafluoride

    NASA Astrophysics Data System (ADS)

    Floyd, M. A.; Morrow, R. W.; Farrar, R. B.

    An analytical method has been developed for the determination of trace impurities in high-purity uranium hexafluoride using liquid-liquid extraction of the uranium from the trace impurities followed by analysis with inductively coupled plasma-atomic emission spectroscopy. Detection limits, accuracy, and precision data are presented.

  4. Fluid-Plasma-Combustion Coupling Effects on the Ignition of a Fuel Jet

    NASA Astrophysics Data System (ADS)

    Massa, Luca; Freund, Jonathan

    2016-11-01

    We analyze the effect of plasma-combustion coupling on the ignition and flame supported by a DBD interacting with a jet of H2 in a air cross-flow. We propose that plasma-combustion coupling is due to the strong temperature-dependence of specific collisional energy loss as predicted by the Boltzmann equation, and that e- transport can be modeled by assuming a form for the E-field pulse in microstreamers. We introduce a two-way coupling based on the Boltzmann equation and the charged species conservation. The addition of this mechanism to a hydrogen combustion scheme leads to an improvement of the ignition prediction and of the understanding of the effect of the plasma on the flow. The key points of the analysis are 1) explanation of the mechanism for the two-stage ignition and quenching observed experimentally, 2) explanation of the existence of a power threshold above which the plasma is beneficial to the ignition probability, 3) understanding of the increase in power absorbed by the plasma in burning conditions and the reduction in power absorbed with an increase in the cross velocity, 4) explanation of the non-symmetric emissions and the increase in luminescence at the rotovibrational H2O band. The model is validated in part against air-H2 flow experiments. This material is based in part upon work supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002374.

  5. Shock structures in a strongly coupled self-gravitating opposite-polarity dust plasma

    SciTech Connect

    Mamun, A. A.; Schlickeiser, R.

    2016-03-15

    A strongly coupled, self-gravitating, opposite-polarity dust plasma (containing strongly coupled inertial positive and negative dust fluids, and inertialess weakly coupled ions) is considered. The generalized hydrodynamic model and the reductive perturbation method are employed to examine the possibility for the formation of the dust-acoustic (DA) shock structures in such an opposite-polarity dust plasma. It has been shown that the strong correlation among charged dust is a source of dissipation and is responsible for the formation of the DA shock structures in such the opposite-polarity dust plasma medium. The parametric regimes for the existence of the DA shock structures (associated with electrostatic and gravitational potentials) and their basic properties (viz., polarity, amplitude, width, and speed) are found to be significantly modified by the combined effects of positively charged dust component, self-gravitational field, and strong correlation among charged dust. The implications of our results in different space plasma environments and laboratory plasma devices are briefly discussed.

  6. Broad ion energy distributions in helicon wave-coupled helium plasma

    NASA Astrophysics Data System (ADS)

    Woller, K. B.; Whyte, D. G.; Wright, G. M.

    2017-05-01

    Helium ion energy distributions were measured in helicon wave-coupled plasmas of the dynamics of ion implantation and sputtering of surface experiment using a retarding field energy analyzer. The shape of the energy distribution is a double-peak, characteristic of radiofrequency plasma potential modulation. The broad distribution is located within a radius of 0.8 cm, while the quartz tube of the plasma source has an inner radius of 2.2 cm. The ion energy distribution rapidly changes from a double-peak to a single peak in the radius range of 0.7-0.9 cm. The average ion energy is approximately uniform across the plasma column including the double-peak and single peak regions. The widths of the broad distribution, ΔE , in the wave-coupled mode are large compared to the time-averaged ion energy, ⟨E ⟩. On the axis (r = 0), ΔE / ⟨E ⟩ ≲ 3.4, and at a radius near the edge of the plasma column (r = 2.2 cm), ΔE / ⟨E ⟩ ˜ 1.2. The discharge parameter space is scanned to investigate the effects of the magnetic field, input power, and chamber fill pressure on the wave-coupled mode that exhibits the sharp radial variation in the ion energy distribution.

  7. Spectroscopic Measurements of Collision-less Coupling Between Laser-Produced, Super-Alfvénic Debris Plasmas and Magnetized, Ambient Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Everson, E.; Schaeffer, D.; Constantin, C.; Vincena, S.; Van Compernolle, B.; Clark, S.; Niemann, C.

    2013-06-01

    Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between super-Alfvénic debris plasmas and magnetized, ambient plasmas of astrophysical relevance. In a recent campaign on the Large Plasma Device (LAPD) utilizing the Phoenix laboratory Raptor laser (130 J, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within magnetized, ambient helium plasmas (nelec ≈ 3×1012 cm-3, Telec ≈ 5.5 eV, B0 = 200 G), and prominent spectral lines of carbon and helium ions were studied in high resolution (˜ 0.01 nm). Time-resolved Doppler shift and width measurements of a C V ion spectral line reveal significant deceleration as the ions stream through the background plasma, which may indirectly indicate momentum coupling. Spectral lines of He II ions are observed to intensify by orders of magnitude and broaden, indicating energy transfer from the debris plasma to the background plasma.

  8. Measurements of secondary scintillation in low-pressure CF4 with a SiPM, from a parallel-plate avalanche geometry

    NASA Astrophysics Data System (ADS)

    Cortesi, M.; Yurkon, J.; Stolz, A.

    2016-04-01

    In this work we report and discuss the characterization of the secondary scintillation light emitted by low-pressure tetrafluoromethane (CF4) during avalanche gas processes. The experimental setup consists of a Parallel Plate Avalanche Counter (PPAC) irradiated by 5.5 MeV alpha particles from a collimated 241-Am source. The PPAC is operated in CF4 at pressures ranging from 5 to 50 torr. The electroluminescence light is readout by a VUV-sensitive Multi-Pixel Photon Counter (MPPC, Hamamatsu), placed along the PPAC axial direction. The secondary scintillation yield at different operational pressures was computed from the correlation between avalanche charge and electroluminesce light, recorded on an event-by-event basis; it was found to be in the range of 0.01-0.15 photons/electron depending on the reduced field applied between the PPAC electrodes. The role of the quencher impurities is also briefly discussed. In addition, the coincidence resolving times (CRT) for 5.5 MeV α -particles crossing the PPAC has been measured; time resolutions of 600 picosecond were achieved at different pressures.

  9. Plasma Etching of superconducting radio frequency cavity by Ar/Cl2 capacitively coupled Plasma

    NASA Astrophysics Data System (ADS)

    Upadhyay, Janardan; Popovic, Svetozar; Valente-Feliciano, Anne-Marie; Phillips, Larry; Vuskovic, Lepsha

    2016-09-01

    We are developing plasma processing technology of superconducting radio frequency (SRF) cavities. The formation of dc self-biases due to surface area asymmetry in this type of plasma and its variation on the pressure, rf power and gas composition was measured. Enhancing the surface area of the inner electrode to reduce the asymmetry was studied by changing the contour of the inner electrode. The optimized contour of the electrode based on these measurements was chosen for SRF cavity processing. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity is used, which previously mechanically polished, buffer chemically etched afterwards and rf tested at cryogenic temperatures for a baseline test. Plasma processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise manner to establish segmented plasma processing. The cavity is rf tested afterwards at cryogenic temperatures. The rf test and surface condition results are presented.

  10. Classical strongly coupled quark-gluon plasma. II. Screening and equation of state

    NASA Astrophysics Data System (ADS)

    Gelman, Boris A.; Shuryak, Edward V.; Zahed, Ismail

    2006-10-01

    We analyze the screening and bulk energy of a classical and strongly interacting plasma of color charges, a model we recently introduced for the description of a quark-gluon plasma at T=(1-3)Tc. The partition function is organized around the Debye-Hückel limit. The linear Debye-Hückel limit is corrected by a virial expansion. For the pressure, the expansion is badly convergent even in the dilute limit. The nonlinear Debye-Hückel theory is studied numerically as an alternative for moderately strong plasmas. We use the Debye theory of solid to extend the analysis to the crystal phase at very strong coupling. The analytical results for the bulk energy per particle compare well with the numerical results from molecular dynamics simulations for all couplings.

  11. Experimental investigations of the plasma radial uniformity in single and dual frequency capacitively coupled argon discharges

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Liu, Yong-Xin; Gao, Fei; Liu, Gang-Hu; Han, Dao-Man; Wang, You-Nian

    2016-12-01

    In the current work, the radial plasma density has been measured by utilizing a floating double probe in single and dual frequency capacitively coupled argon discharges operated in a cylindrical reactor, aiming at a better understanding of electromagnetic effects and exploring a method of improving the radial uniformity. The experimental results indicate that for single-frequency plasma sustained at low pressure, the plasma density radial profile exhibits a parabolic distribution at 90 MHz, whereas at 180 MHz, the profile evolves into a bimodal distribution, and both cases indicate poor uniformities. With increasing the pressure, the plasma radial uniformity becomes better for both driving frequency cases. By contrast, when discharges are excited by two frequencies (i.e., 90 + 180 MHz), the plasma radial profile is simultaneously influenced by both sources. It is found that by adjusting the low-frequency to high-frequency voltage amplitude ratio β, the radial profile of plasma density could be controlled and optimized for a wide pressure range. To gain a better plasma uniformity, it is necessary to consider the balance between the standing wave effect, which leads to a maximum plasma density at the reactor center, and the edge field effect, which is responsible for a maximum density near the radial electrode edge. This balance can be controlled either by selecting a proper gas pressure or by adjusting the ratio β.

  12. ECH/EBW Plasma Coupling and Heating Experiments on the Proto-MPEX

    NASA Astrophysics Data System (ADS)

    Bigelow, Tim; Caughman, John; Caneses, Juan; Diem, Stephanie; Goulding, Richard; Kafle, Nischal; Rapp, Juergen

    2016-10-01

    ECH and EBW have been under development on the Proto-Material Plasma Exposure eXperiment device (Proto-MPEX) to provide additional plasma electron heating. Proto-MPEX has a linear magnetic field configuration and a helicon plasma source that forms a high-density medium-temperature central core plasma of typically 0.08m diameter. A plasma density of up to 6x1019m-3 is generated which is >6 times over-dense for 28 GHz microwave power available from the experiment's gyrotron system. Modeling using Genray-C code has indicated that some heating of the plasma core should be possible at this frequency using the optimum O-X-EBW coupling scheme. Several improvements to the waveguide system have been made to increase the reliable operating power level and launch beam quality. To improve the plasma heating efficiency, work is underway to optimize the beam launch by adding a remotely adjustable launch angle, adding a polarization rotating miter bend, moving the launch point closer to the plasma edge and providing some beam focusing. Preliminary heating experiments have indicated some over-dense heating has been achieved. A launch power of 75 kW has been achieved out of a possible 150 kW. This work was supported by the U.S. D.O.E. contract DE-AC05-00OR22725.

  13. Influence of finite geometrical asymmetry of the electrodes in capacitively coupled radio frequency plasma

    SciTech Connect

    Bora, B. Soto, L.

    2014-08-15

    Capacitively coupled radio frequency (CCRF) plasmas are widely studied in last decades due to the versatile applicability of energetic ions, chemically active species, radicals, and also energetic neutral species in many material processing fields including microelectronics, aerospace, and biology. A dc self-bias is known to generate naturally in geometrically asymmetric CCRF plasma because of the difference in electrode sizes known as geometrical asymmetry of the electrodes in order to compensate electron and ion flux to each electrode within one rf period. The plasma series resonance effect is also come into play due to the geometrical asymmetry and excited several harmonics of the fundamental in low pressure CCRF plasma. In this work, a 13.56 MHz CCRF plasma is studied on the based on the nonlinear global model of asymmetric CCRF discharge to understand the influences of finite geometrical asymmetry of the electrodes in terms of generation of dc self-bias and plasma heating. The nonlinear global model on asymmetric discharge has been modified by considering the sheath at the grounded electrode to taking account the finite geometrical asymmetry of the electrodes. The ion density inside both the sheaths has been taken into account by incorporating the steady-state fluid equations for ions considering that the applied rf frequency is higher than the typical ion plasma frequency. Details results on the influences of geometrical asymmetry on the generation of dc self-bias and plasma heating are discussed.

  14. Self-Diffusion and Non-Markovian Dynamics in Strongly Coupled Ultracold Neutral Plasmas

    NASA Astrophysics Data System (ADS)

    Strickler, Trevor; Langin, Thomas; McQuillen, Patrick; Killian, Thomas

    2015-05-01

    Collisional processes in weakly coupled plasmas are well-described by the Landau-Spitzer formalism. Classical plasma theory breaks down, however, in strongly coupled systems because of the non-perturbative nature of particle interactions, and improving our understanding of this regime is an important fundamental challenge. We present experimental measurements of the self-diffusion constant and observation of non-Markovian equilibration for strongly coupled ions in an ultracold neutral plasma (UCNP) created by photoionizing strontium atoms in a magneto-optical trap. Our diagnostic uses optical pumping to create ``spin-tagged'' subpopulations of ions having skewed velocity distributions that then relax back to equilibrium. A Green-Kubo relation is used to extract the self-diffusion constant from the equilibration curves. With improved time resolution (down to 30 ns), we have explored the early time dynamics of these skewed ion distributions within 100 ns after the optical pumping, where molecular dynamics simulations predict non-Markovian deviations from the exponential velocity damping expected for weakly coupled systems. At longer times, we observe oscillations of the average velocity during the relaxation, which indicate coupling of single-particle motion to collective modes. This work was supported by the United States National Science Foundation and the Department of Energy (PHY-0714603), and the Air Force Office of Scientific Research (FA9550-12-1-0267).

  15. Continuum Lowering and Fermi-Surface Rising in Strongly Coupled and Degenerate Plasmas

    NASA Astrophysics Data System (ADS)

    Hu, S. X.

    2017-08-01

    Continuum lowering is a well known and important physics concept that describes the ionization potential depression (IPD) in plasmas caused by thermal- or pressure-induced ionization of outer-shell electrons. The existing IPD models are often used to characterize plasma conditions and to gauge opacity calculations. Recent precision measurements have revealed deficits in our understanding of continuum lowering in dense hot plasmas. However, these investigations have so far been limited to IPD in strongly coupled but nondegenerate plasmas. Here, we report a first-principles study of the K -edge shifting in both strongly coupled and fully degenerate carbon plasmas, with quantum molecular dynamics calculations based on the all-electron density-functional theory. The resulting K -edge shifting versus plasma density, as a probe to the continuum lowering and the Fermi-surface rising, is found to be significantly different from predictions of existing IPD models. In contrast, a simple model of "single-atom-in-box," developed in this work, accurately predicts K -edge locations as ab initio calculations provide.

  16. Continuum Lowering and Fermi-Surface Rising in Strongly Coupled and Degenerate Plasmas

    DOE PAGES

    Hu, S. X.

    2017-08-10

    Here, continuum lowering is a well-known and important physics concept that describes the ionization potential depression (IPD) in plasmas caused by thermal-/pressure-induced ionization of outer-shell electrons. The existing IPD models are often used to characterize plasma conditions and to gauge opacity calculations. Recent precision measurements have revealed deficits in our understanding of continuum lowering in dense hot plasmas. However, these investigations have so far been limited to IPD in strongly coupled but nondegenerate plasmas. Here, we report a first-principles study of the K-edge shifting in both strongly coupled and fully degenerate carbon plasmas, with quantum molecular dynamics (QMD) calculations basedmore » on the all-electron density-functional theory (DFT). The resulted K-edge shifting versus plasma density, as a probe to the continuum lowering and the Fermi-surface rising, is found to be significantly different from predictions of existing IPD models. In contrast, a simple model of “single atom in box” (SAIB), developed in this work, accurately predicts K-edge locations as what ab-initio calculations provide.« less

  17. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    SciTech Connect

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Kline, J. L.; MacDonald, M. J.; Sefkow, A. B.; Yin, L.; Betti, R.

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled using the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.

  18. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    SciTech Connect

    Montgomery, D. S. Albright, B. J.; Kline, J. L.; Yin, L.; Barnak, D. H.; Chang, P. Y.; Davies, J. R.; Fiksel, G.; Froula, D. H.; Betti, R.; MacDonald, M. J.; Sefkow, A. B.

    2015-01-15

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with B{sub z} ≤ 7.5-T. We found that an external field B{sub z} = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. The experiments were modeled using the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.

  19. Use of external magnetic fields in hohlraum plasmas to improve laser-coupling

    DOE PAGES

    Montgomery, D. S.; Albright, B. J.; Barnak, D. H.; ...

    2015-01-13

    Efficient coupling of laser energy into hohlraum targets is important for indirect drive ignition. Laser-plasma instabilities can reduce coupling, reduce symmetry, and cause preheat. We consider the effects of an external magnetic field on laser-energy coupling in hohlraum targets. Experiments were performed at the Omega Laser Facility using low-Z gas-filled hohlraum targets which were placed in a magnetic coil with Bz ≤ 7.5-T. We found that an external field Bz = 7.5-T aligned along the hohlraum axis results in up to a 50% increase in plasma temperature as measured by Thomson scattering. As a result, the experiments were modeled usingmore » the 2-D magnetohydrodynamics package in HYDRA and were found to be in good agreement.« less

  20. 40 CFR Appendix C to Part 136 - Inductively Coupled Plasma-Atomic Emission Spectrometric Method for Trace Element Analysis of...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Inductively Coupled Plasma-Atomic... to Part 136—Inductively Coupled Plasma—Atomic Emission Spectrometric Method for Trace Element... technique. Samples are nebulized and the aerosol that is produced is transported to the plasma torch where...