Measurement of electron-transport coefficients in O by a double-shutter drift-tube method

Yoshida, Kenichi; Sasaki, Naoto; Ohuchi, Hitoshi; Hasegawa, H.; Shimozuma, M.; Tagashira, Hiroaki

doi:10.1088/0022-3727/32/8/004

Cited by 8 publications

(12 citation statements)

References 23 publications

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“…3 The purity of C 2 F 4 employed is more than 98%, according to the manufacturer ͑ABCR GmbH & Co. KG͒.…”

Section: A the Experimental Apparatus And Analytical Methodsmentioning

confidence: 99%

“…We first tried using the measured ionization and the calculated momentum transfer and excitation cross sections in our swarm analysis, merely scaling the magnitudes of the cross sections in order to fit the measured swarm data as we did in our work on CHF 3 . 29 This approach gave unrealistic results for the excitation cross sections, so we returned to the more sophisticated approach of adjusting both the energy dependencies and the magnitudes of the cross sections.…”

Section: Boltzmann's Equation and The Downhill Simplexmentioning

confidence: 99%

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Electron transport properties and collision cross sections in C2F4

Yoshida

Goto

Tagashira

et al. 2002

Journal of Applied Physics

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We have measured the electron drift velocity, longitudinal diffusion coefficient, and ionization coefficient in tetrafluoroethene (C2F4). Using these data and the results of ab initio calculations of the elastic, momentum-transfer, and neutral-excitation cross sections, along with measurements of the partial ionization cross sections, we have performed a swarm analysis in order to construct a self-consistent set of electron impact cross sections for C2F4. The swarm analysis consists of solutions to Boltzmann’s equation for electrons in C2F4 for values of E/N⩽500 Td and direct Monte Carlo simulation of electron transport in C2F4 for 500 Td⩽E/N⩽2000 Td. We present an analysis and discussion of the sensitivity of cross sections derived from swarm data to uncertainties in the electron transport measurements. We also discuss the failure of the two-term spherical harmonic solution to Boltzmann’s equation for E/N>500 Td, which necessitated the use of Monte Carlo simulations for high values of E/N.

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“…3 The purity of C 2 F 4 employed is more than 98%, according to the manufacturer ͑ABCR GmbH & Co. KG͒.…”

Section: A the Experimental Apparatus And Analytical Methodsmentioning

confidence: 99%

Section: Boltzmann's Equation and The Downhill Simplexmentioning

confidence: 99%

Electron transport properties and collision cross sections in C2F4

Yoshida

Goto

Tagashira

et al. 2002

Journal of Applied Physics

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“…From the highest measured E/N values above 120 Td and highest measured pressures above above 10 kPa we estimate that the mobility of these stable anions is roughly 20 − 30% higher than the one of the positive ion. Reference values from dedicated measurements for electron mobility (Yoshida [47,53]) and electron longitudinal diffusion (Nakamura [53,54] Our values for the ionization rate coefficient are shown in figure 4. They are in good agreement with most references.…”

Section: Resultsmentioning

confidence: 99%

“…Yoshida, Sasaki, Ohuchi and Hasegawa [47], 1999, measured the ionization and dissociative attachment rate coefficients of pure N 2 O over a large E/N range. Yousfi, Hennad and Benhenni [26] calculated cross sections, mean energies and mobilities for anions in N 2 O.…”

Section: Later Workmentioning

confidence: 99%

Measurement and modeling of electron and anion kinetics in N₂O discharges

Hösl

Pachin

Egüz

et al. 2020

J. Phys. D: Appl. Phys.

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From Pulsed Townsend measurements in nitrous oxide (N2O) we obtain swarm parameters for various electron and in particular anion processes. We discuss various assumptions on the discharge model in literature, and motivate a suitable model. Our findings agree with modern sources on the electron swarm parameters. Contrary to many sources however we find evidence for electron detachment from O-with a coefficient of ≈ 3.2 • 10 −20 m 2 , and we suggest further changes to the commonly accepted discharge model. Based on the obtained swarm parameters, an electric strength dependent on pressure is estimated and compared to breakdown measurements.

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“…Yoshida et al [61,63] calcularam três parâmetros de transporte do metano e do óxido nitroso, incluindo α/N, empregando a equação de transporte de elétrons proposta por Kondo e Tagashira [69] a espectros de tempo de chegada, ATS.…”

Section: Técnica De Tempo De Voounclassified

Medidas do primeiro coeficiente de Townsend de ionização em misturas gasosas utilizadas em microdosimetria

Petri¹

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RESUMOMicrodosímetros gasosos geralmente empregam uma mistura gasosa equivalente ao tecido humano mole (Tissue-equivalent Gas -TEG), composta de um hidrocarboneto, dióxido de carbono e nitrogênio, de forma que o poder de freamento na mistura e no tecido sejam semelhantes. Entretanto, independentemente do hidrocarboneto adotado, dados tanto teóricos como experimentais do primeiro coeficiente de Townsend de ionização (α) nestas misturas são raros, ainda que a primeira TEG, cujo metano é o gás majoritário, tenha sido proposta em 1956 por Rossi e Failla e continue sendo amplamente utilizada. Neste trabalho, dados do parâmetro α em TEGs baseadas no metano (CH 4 -64,4%, CO 2 -32,4% e N 2 -3,2%) e nos isômeros do butano (C 4 H 10 -51,4%, CO 2 -42,3% e N 2 -6,3%) são apresentados pela primeira vez em geometria planar para a faixa de campo elétrico normalizado pela densidade do gás (E/N) entre 100 -290 Td (1 Td = 10 -21 V.m 2 ). O método de medidas adotado baseia-se na técnica de Townsend pulsada, onde o primeiro coeficiente de Townsend pode ser determinando comparando a corrente elétrica no regime de avalanche e a corrente de ionização primária gerada pela incidência de um feixe de laser de nitrogênio em um eletrodo metálico (catodo) de uma câmara de geometria planar, sendo o anodo um eletrodo de alta resistividade (ρ=2×10 10 .m). O aparato experimental, até então operado apenas em pressão atmosférica, foi modificado para também trabalhar em baixa pressão (120 hPa), de modo a aumentar a faixa de E/N investigada. A validação do método e das alterações do sistema de detecção foi realizada utilizando os três gases componentes das TEGs cujos parâmetros de transporte são amplamente estudados: o nitrogênio, o dióxido de carbono e o metano. Observou-se que o parâmetro α na TEG com metano assemelha-se com os valores determinados para o metano puro. Na TEG baseada no isobutano, ele é compatível com o primeiro coeficiente de Townsend do dióxido de carbono para campos acima de 170 Td. Já o parâmetro α na mistura com n-butano é intermediário entre os valores obtidos para o dióxido de carbono e o nitrogênio. Os resultados experimentais, disponíveis em forma tabular, foram comparados com os simulados utilizando o programa Magboltz 2, evidenciando boa concordância dentro da incerteza experimental. ABSTRACTGaseous microdosimeters usually employ a Tissue-equivalent Gas (TEG), made of a hydrocarbon, carbon dioxide and nitrogen, in order to make similar the stopping power in this mixture and in the human soft tissue. Notwithstanding, regardless the chosen hydrocarbon, both theoretical and experimental data on the first Townsend ionization coefficient (α) in this mixtures are rare, even though the first TEG, which methane is the most abundant gas, was proposed in 1956 by Rossi and Failla and it has been widely employed since then. In this work, data on the parameter α in TEGs based on methane (CH 4 -64.4%, CO 2 -32.4%, and N 2 -3.2%) and butane's isomers (C 4 H 10 -51.4%, CO 2 -42.3% e N 2 -6.3%) are presented for the first time in planar ...

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Measurement of electron-transport coefficients in O by a double-shutter drift-tube method

Cited by 8 publications

References 23 publications

Electron transport properties and collision cross sections in C2F4

Electron transport properties and collision cross sections in C2F4

Measurement and modeling of electron and anion kinetics in N₂O discharges

Medidas do primeiro coeficiente de Townsend de ionização em misturas gasosas utilizadas em microdosimetria

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Measurement of electron-transport coefficients in O by a double-shutter drift-tube method

Cited by 8 publications

References 23 publications

Electron transport properties and collision cross sections in C2F4

Electron transport properties and collision cross sections in C2F4

Measurement and modeling of electron and anion kinetics in N2O discharges

Medidas do primeiro coeficiente de Townsend de ionização em misturas gasosas utilizadas em microdosimetria

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Measurement and modeling of electron and anion kinetics in N₂O discharges