Positive Ions in the Afterglow of a Low Pressure Helium Discharge

Phelps, A. V.; Brown, Sanborn C.

doi:10.1103/physrev.86.102

Cited by 183 publications

(30 citation statements)

References 11 publications

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“…The abundant He þ 2 is formed through the ion conversion channel (He þ þ 2He ! He þ 2 þ He), which was first found by Phelps and Brown [29]. The average electron temperature is nearly uniform across the gap and is as Fig.…”

Section: Comparison Of the Discharged Current Between The Simulation mentioning

confidence: 81%

Investigation of the Atmospheric Helium Dielectric Barrier Discharge Driven by a Realistic Distorted-Sinusoidal Voltage Power Source

Hung

Chiu

Hwang

et al. 2010

Plasma Chem Plasma Process

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The non-equilibrium atmospheric-pressure parallel-plate helium dielectric barrier discharge (DBD) driven by a realistic 20 kHz distorted-sinusoidal voltage waveform has been investigated by means of simulations and experiments. A self-consistent onedimensional fluid modeling code considering the non-local electron energy balance was applied to simulate the helium DBD. The effect of selecting plasma chemistry was investigated by comparing simulations with experiments. The results show that the simulations, which include more excited helium, metastable helium and electron-ion-related reaction channels, can faithfully reproduce the measured discharged temporal current quantitatively. Based on the simulated discharge properties, we have found that there is complicated mode transition of discharges from the long Townsend-like to the ''dark current''-like, then to the short primary Townsend-like and the short secondary Townsend-like for the helium DBD that is driven by a realistic distorted-sinusoidal voltage power source. Discharge properties in different periods of discharge are discussed in detail in the paper.

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Section: Comparison Of the Discharged Current Between The Simulation mentioning

confidence: 81%

Investigation of the Atmospheric Helium Dielectric Barrier Discharge Driven by a Realistic Distorted-Sinusoidal Voltage Power Source

Hung

Chiu

Hwang

et al. 2010

Plasma Chem Plasma Process

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show abstract

“…It appears that earlier measurements [8][9][10][11][12][13][73][74][75][76][77][78][79][80][81][82][83][84] of the mobilities of 4 He + ions in 4 He were subject to end effects, injection effects and perhaps other complications. This probably accounts for the differences shown in Fig.…”

Section: Experimental Mobilitiesmentioning

confidence: 99%

Transport coefficients of He+ ions in helium

Viehland

Johnsen

Gray

et al. 2016

The Journal of Chemical Physics

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“…Particularly, He + 2 is the dominant ion in the fundamental helium plasmas and in the helium afterglow at pressures above ∼5 mbar [12] and at room temperature (while atomic ions dominate the low-pressure He afterglows or at higher temperature). In the helium plasma, He + 2 is created in either three-body [13] or binary collisions [12,14] giving ions with a significant rovibrational excitation [12,15]. The helium afterglow is characterized by a strong recombination of electrons and molecular ions and the simultaneous occurrence of excited (triplet) helium atoms [16].…”

Section: Pacs Numbersmentioning

confidence: 99%

Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

et al. 2005

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The dissociative recombination (DR) of 3 He 4 He + has been investigated at the heavy-ion Test Storage Ring (TSR) in Heidelberg by observing neutral products from electron-ion collisions in a merged beams configuration at relative energies from near-zero (thermal electron energy about 10 meV) up to 40 eV. After storage and electron cooling for 35 s, an effective DR rate coefficient at nearzero energy of 3 × 10 −9 cm 3 s −1 is found. The temporal evolution of the neutral product rates and fragment imaging spectra reveals that the populations of vibrational levels in the stored ion beam are non-thermal with fractions of ∼0.1-1% in excited levels up to at least v = 4, having a significant effect on the observed DR signals. With a pump-probe-type technique using DR fragment imaging while switching the properties of the electron beam, the vibrational excitation of the ions is found to originate mostly from ion collisions with the residual gas. Also, the temporal evolution of the DR signals suggests that a strong electron induced rotational cooling occurs in the vibrational ground state, reaching a rotational temperature near or below 300 K. From the absolute rate coefficient and the shape of the fragment imaging spectrum observed under stationary conditions, the DR rate coefficient from the vibrational ground state is determined; converted to a thermal electron gas at 300 K it amounts to (3.3 ± 0.9) × 10 −10 cm 3 s −1 . The corresponding branching ratios from v = 0 to the atomic final states are found to be (3.7 ± 1.2)% for 1s2s 3 S, (37.4 ± 4.0)% for 1s2s 1 S, (58.6 ± 5.2)% for 1s2p 3 P , and (2.9 ± 3.0)% for 1s2p 1 P . A DR rate coefficient in the range of 2 × 10 −7 cm 3 s −1 or above is inferred for vibrational levels v = 3 and higher. As a function of the collision energy, the measured DR rate coefficient displays a structure around 0.2 eV. At higher energies, it has one smooth peak around 7.3 eV and a highly structured appearance at 15-40 eV. The small size of the observed effective DR rate coefficient at near-zero energy indicates that the electron induced rotational cooling is due to inelastic electron-ion collisions and not due to selective depletion of rotational levels by DR.

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Positive Ions in the Afterglow of a Low Pressure Helium Discharge

Abstract: The production and loss of He + and He 2 ions in the afterglow of a low pressure with the value of 12 cm2/volt-sec calculated using the quantum mechanical interaction of the He+ ion and the neutral helium atom.

Cited by 183 publications

References 11 publications

Investigation of the Atmospheric Helium Dielectric Barrier Discharge Driven by a Realistic Distorted-Sinusoidal Voltage Power Source

Investigation of the Atmospheric Helium Dielectric Barrier Discharge Driven by a Realistic Distorted-Sinusoidal Voltage Power Source

Transport coefficients of He+ ions in helium

Dissociative recombination and low-energy inelastic electron collisions of the helium dimer ion

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