Total electron-impact excitation cross sections of helium

Brongersma, H.H.; Knoop, F.W.E.; Backx, C.

doi:10.1016/0009-2614(72)80032-0

Cited by 57 publications

(7 citation statements)

References 12 publications

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“…As indicated in the last section, the sensitivity of the AIG is enhanced in the mixture of helium and hydrogen in the helium concentration rate of 3 -15%. Assuming that the increase of sensitivity was caused only by the Penning transfer, the change of the AIG sensitivity is expected in the parameter of the AIG is around 10 -20% [4]. Therefore the enhancement of the sensitivity observed in the current experiment can be explained well by the Penning transfer process.…”

Section: Effect Of Penning Transfersupporting

confidence: 51%

“…where σ e−He + is the electron-impact ionization crosssection of helium, σ e−He * is the electron-impact excitation cross-section of metastable helium and σ He * −H + is the cross-section of the Penning transfer ionization. Typically, at the electron collision energy in the AIG, the value of N H corresponds to 10% of N H + , the value of the σ e−He * corresponds to 1 -2% of σ e−H + and the value of σ He * −H + is 100 times larger than σ e−H + [4]. Therefore if the Penning transfer is occurring, the sensitivity is expected to be increased by 10 -20%.…”

Section: Penning Transfer In Mixed Gasesmentioning

confidence: 99%

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Study on the Sensitivity of Fast Ionization Gauge in Mixture Gas of Hydrogen and Helium

Ichimura

Yamashita

Nakashima

et al. 2019

Plasma and Fusion Research

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The characteristics of the gas pressure measurement with the ASDEX type fast ionization gauge (AIG) in the mixture of Hydrogen and Helium is studied in this research. The calibration test stand capable of reproducing the mixture gas environment is assembled and used for the experimental calibration of the ionization gauge. In the experiment, the sensitivity of the AIG against pure hydrogen and pure helium is evaluated in order to eliminate the effect of individual differences among the AIG sensors. The mixture ratio of He in the test stand chamber is controlled from 3% to 15% to simulate the environment in divertor regions of fusion reactors. In the mixture gas, enhancement of the gauge sensitivity around 13% was observed. The enhancement of ionization due to the Penning Transferrer reactions, between the hydrogen atom and the metastable-helium atom is considered to be the main cause of the sensitivity change. Also it is found that the degree of enhancement of the AIG sensitivity can be changed drastically due to the condition of the AIG sensor. The monitoring or predicting the population of metastable-helium atoms will be important for the measurement of the mixture gas pressures.

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Section: Effect Of Penning Transfersupporting

confidence: 51%

Section: Penning Transfer In Mixed Gasesmentioning

confidence: 99%

Study on the Sensitivity of Fast Ionization Gauge in Mixture Gas of Hydrogen and Helium

Ichimura

Yamashita

Nakashima

et al. 2019

Plasma and Fusion Research

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“…We can compare the different rates of excitations a ~k of the levels 1, 2, 3, 4 from the ground state without knowing the value of the coefficient f(u1): average values from those obtained in different investigations (Corrigan and von Engel 1958, Holt and Krotkov 1966, Jobe and St. John 1967, Brongersma and Knoop 1972, Rice et aZl972, Donaldson et aZ1972, Hall et al 1973, Trajmar 1973. We can introduce also the total frequency of inelastic collisions A = Ca'oTNJy where…”

Section: To Obtain C L O ~mentioning

confidence: 99%

Level population densities and line intensities in helium discharges at intermediate pressures

Dothan¹,

Kagan²

1981

J. Phys. D: Appl. Phys.

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A scheme for calculating populations of excited levels and intensities of spectral lines in the positive column of helium discharges at intermediate pressures (p>5 Torr) is proposed. The electron distribution obtained from the Boltzmann equation is taken into account. The distribution is strongly non-Maxwellian for electrons of energy more than 19.8 eV. Concentrations of atoms on excited levels (n=2,3,4,5) are obtained from balance equations for the population of those levels. The concentration of level 23S is the highest. The concentration of 21S is much less than that which would exist in the case of quasithermodynamic equilibrium between levels 23S and 21S. The population of higher levels (n>2) is determined by excitation from levels 23S and 21S. For singlet levels the excitation from level 21S is important. Population inversion is obtained between levels 31P-31D, 41P-41D, 51S-41P, 43S-33P, 53S-43P and 53P-43D.

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“…The curve from threshold to 29 eV was obtained by the authors with a separate experimental set-up using the technique described in a previous paper [33]. This curve was placed on an absolute scale by normalizing the first peak to the value of 4.0 x 10-18 cm' which was obtained by Brongersma and co-workers [34]. As can be seen the cross section is low at 29 eV but considering the experimental uncertainties inherent in this technique (which become large as the energy from threshold increases), the agreement is not unreasonable.…”

Section: 1 S Excitation Cross Section -Experi-mentioning

confidence: 99%

Electron impact differential and integral cross sections for excitation of the n = 2 states of helium at 29.2 eV, 39.2 eV and 48.2 eV

et al. 1973

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A high resolution electron impact spectrometer using electrostatic monochromators and the cross-beam technique is described. Considerations related to its construction and use in measuring cross-sections are discussed. This instrument has been used to obtain absolute values for differential and integral excitation cross-sections of the n = 2 manifold states of helium at 29.2 eV, 39.2 eV and 48.2 eV. The observations are presented and compared with currently available theoretical calculations

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Total electron-impact excitation cross sections of helium

Cited by 57 publications

References 12 publications

Study on the Sensitivity of Fast Ionization Gauge in Mixture Gas of Hydrogen and Helium

Study on the Sensitivity of Fast Ionization Gauge in Mixture Gas of Hydrogen and Helium

Level population densities and line intensities in helium discharges at intermediate pressures

Electron impact differential and integral cross sections for excitation of the n = 2 states of helium at 29.2 eV, 39.2 eV and 48.2 eV

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