Experimental investigation of minority ion concentration in a weakly ionized hydrogen plasma

Alba, S.; Fontanesi, M.; Galassi, A.; Petrillo, V.; Riccardi, C.; Sindoni, E.

doi:10.1088/0741-3335/35/2/011

Cited by 13 publications

(9 citation statements)

References 9 publications

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“…Further, high concentra- [4] tions of vibrationally excited hydrogen molecules and consequently negative ions of hydrogen require the presence of highly energetic primary electrons called "suprathermal" electrons.5'27 Since HF powers applied in copper PACVD are low and no "suprathermal" electron sources are present, the contribution of both the excited species and It can be neglected in the development of the H2 discharge model. [24][25][26][27][28][29] Consequently, here the plasma is assumed to be a mixture of positive ions, elctrons, and atomic hydrogen only.…”

Section: Infroductionmentioning

confidence: 99%

Comparison of Experiments with a Lumped Parameter Model of the Plasma Assisted Chemical Vapor Deposition of Copper

Lakshmanan

Gill

1998

J. Electrochem. Soc.

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Experiments show that pure copper films can be formed at temperatures below 190 °C by H2 plasma assisted chemically vapor deposited copper(II)-hexafluoroacetylacetonate. A fundamental surface reaction mechanism has been derived for the reaction between dissociatively adsorbed precursor and atomic hydrogen produced in the plasma. The mechanism suggests that the deposition rate is proportional to [Cu(HFA),] 1/2 [H] and film purity improves with an increase in atomic hydrogen concentration. A new lumped parameter model has also been developed that agrees very well with experiments, to relate the operating conditions to the concentrations of Cu(HFA)2 and atomic hydrogen. Our model shows that at temperatures above 200 °C, surface recombination of atomic hydrogen decreases adsorbed [H] leading to copper films possessing high resistivity. It also indicates that at plasma powers above 60 W, high electron concentrations lead to the gasphase decomposition of the precursor and high film resistivity. An apparent activation energy of 5.0 kcal/mol is also suggested for the deposition, by the experiments and the reactor model.

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Section: Infroductionmentioning

confidence: 99%

Comparison of Experiments with a Lumped Parameter Model of the Plasma Assisted Chemical Vapor Deposition of Copper

Lakshmanan

Gill

1998

J. Electrochem. Soc.

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“…The theory, discussed in section 2, concerns the analysis of the wave potential emitted from different kinds of source, considering both the cold and warm plasma approximations [8]. The experimental analysis has been performed in the Thorello device, a toroidal system producing a steady-state magnetized plasma [9][10][11][12]. The ion resonance cones have been excited with different antenna systems and plasma parameters and have been detected using an interferometric system.…”

Section: Introductionmentioning

confidence: 99%

Ion resonance cones in a magnetized plasma

Riccardi¹,

Salierno²,

Cantù³

et al. 1996

Plasma Phys. Control. Fusion

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“…Measurements of IBWs to determine minority ion concentrations in weakly ionized hydrogen gases have been made using probes in the Thorello and Blaamann devices, respectively [5,6]. Measurements with far-infrared CTS of externally excited IBWs in plasmas were done at Microtor [7,8], ACT-1 [9], and Alcator-C [10] where the wave dispersion of an IBW was obtained in shot-by-shot scans of the scattering angle, i.e., for different wave vectors.…”

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confidence: 99%

Measurements of Intrinsic Ion Bernstein Waves in a Tokamak by Collective Thomson Scattering

et al. 2011

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In this Letter we report measurements of collective Thomson scattering (CTS) spectra with clear signatures of ion Bernstein waves and ion cyclotron motion in tokamak plasmas. The measured spectra are in accordance with theoretical predictions and show clear sensitivity to variation in the density ratio of the main ion species in the plasma. Measurements with this novel diagnostic demonstrate that CTS can be used as a fuel ion ratio diagnostic in burning fusion plasma devices. Waves and particle dynamics in the frequency range of ion cyclotron motion (ICM), ! ci ¼ q i B=m i , play important roles for diagnostic of ion composition in magnetized plasmas. Under certain conditions collective Thomson scattering (CTS) spectra are distinctively sensitive to ion Bernstein waves (IBWs) and the ICM. The combined effect of IBWs and ICM gives rise to an ion cyclotron structure (ICS) in CTS spectra which depend on the ion species densities and their ratios. Measurements of the ICS in CTS spectra can thus demonstrate basic plasma and wave physics as well as provide great diagnostic potential for characterizing the composition of magnetized plasmas.We present in this Letter the first measurements of CTS spectra with signatures of intrinsic IBWs and ICM in a multispecies tokamak plasma. In experiments on multispecies plasmas containing, e.g., hydrogen, deuterium, and 3 He, we demonstrate that we resolve changes in the ICS in CTS spectra caused by variations in the isotope ratios. In addition, calculations and experimental results agree. This indicates that the relevant physics of CTS and the interaction with IBWs and ICM are well represented by our kinetic, fully electromagnetic model.While our results are of general interest and have application in plasma physics, there is a particular implication on the field of fusion energy research. The issue of measuring the fuel ion ratio in future burning plasma magnetic confinement devices has recently received increasing attention. The fuel ion ratio in burning plasmas is the ratio of the number densities of the main ion species. On ITER it is not clear if this ratio can be determined in the plasma center (normalized radius < 0:3) with the diagnostic set currently included in the ITER baseline design [1]. As measurements of the fuel ion ratio are of high priority for machine protection and basic control, it is of great interest to develop alternative diagnostic methods capable of measuring the tritium-deuterium ratio. Our results represent a key step for developing a novel CTS-based fuel ion ratio diagnostic which can fulfill the measurement needs for ITER and future devices.IBWs are electrostatic hot plasma waves generally present in magnetized plasmas [2,3]. IBWs are weakly damped for propagation near perpendicular to the magnetic field (k k % 0) while the damping of the waves increases strongly as k k increases. The frequencies of propagating IBWs lie between the harmonics of the cyclotron frequency for each ion species in the plasma, ! ci . The frequencies of IBWs with wave vectors...

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Experimental investigation of minority ion concentration in a weakly ionized hydrogen plasma

Cited by 13 publications

References 9 publications

Comparison of Experiments with a Lumped Parameter Model of the Plasma Assisted Chemical Vapor Deposition of Copper

Comparison of Experiments with a Lumped Parameter Model of the Plasma Assisted Chemical Vapor Deposition of Copper

Ion resonance cones in a magnetized plasma

Measurements of Intrinsic Ion Bernstein Waves in a Tokamak by Collective Thomson Scattering

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