Absolute measurement of low-energy H0 fluxes by a secondary emission detector

Ray, J. A.; Barnett, C. F.; Zyl, B. Van

doi:10.1063/1.325747

Cited by 51 publications

(15 citation statements)

References 17 publications

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“…Carefully designed electrostatic shielding in the experiment by Keller and Cooper 9 ensured the exclusion of stray secondary electrons from enhancing the measured O Ϫ detection efficiency; it was thus concluded that the difference might be due to different secondary electron coefficients for O ϩ and O Ϫ impacting a CEM surface. To this date, this has not been directly measured for oxygenic species, however Ray et al 27 have shown this to be the case for H Ϫ , H, and H ϩ impacting a gas covered Cu surface. Their results indicate that the secondary negative emission ͑the sum of electrons and ions͒ from H Ϫ is nearly an order of magnitude greater than those from H and H ϩ ͑both similar in value͒ for EՇ1000 eV.…”

Section: Resultsmentioning

confidence: 98%

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Stephen

Peko

2000

Review of Scientific Instruments

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Articles you may be interested inThomson spectrometer-microchannel plate assembly calibration for MeV-range positive and negative ions, and neutral atoms Rev. Sci. Instrum. 84, 053302 (2013); 10.1063/1.4803670Gamma-ray detection efficiency of the microchannel plate installed as an ion detector in the low energy particle instrument onboard the GEOTAIL satellite Rev. Sci. Instrum. 78, 034501 (2007);Absolute detection efficiencies of a commercial multichannel plate detector have been measured for O, O ϩ , and O Ϫ , impacting at normal incidence for energies ranging from 30-1000 eV. In addition, the detection efficiencies for O relative to its ions are presented, as they may have a more universal application. The absolute detection efficiencies are strongly energy dependent and significant differences are observed for the various charge states at lower energies. The detection efficiencies for the different charge states appear to converge at higher energies. The strongest energy dependence is for O ϩ ; the detection efficiency varies by three orders of magnitude across the energy range studied. The weakest dependence is for O Ϫ , which varies less than one order of magnitude.

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Section: Resultsmentioning

confidence: 98%

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Stephen

Peko

2000

Review of Scientific Instruments

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“…RsC where the y represents the "potential ejection" of electrons and is small for hydrogen ions [6,8,26], the kv term is an approximation to the contribution of "kinetic" ejection of electrons [6,8,26], and the kI term represents the first-order effects of space charge on the electric field and, thereby, the electron yield at the cathode. In the second term of Eq.…”

Section: Model Of Transients In Low-current Dischargesmentioning

confidence: 99%

“…, H in Hz. A near linear variation of yield with Vis typical of electron yields at ion (and neutral atom) energies of the order of 100 eV [26]. The term proportional to I was proposed by Rogowski [16] and assumes that the energy of the ions striking the cathode is determined by the E/n at the cathode, as would be appropriate for ions with a short mean-free path for charge-transfer collisions.…”

Section: Model Of Transients In Low-current Dischargesmentioning

confidence: 99%

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Oscillations of low-current electrical discharges between parallel-plane electrodes. III. Models

1993

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Simple models are developed to describe the results of measurements of the oscillatory and negative differential resistance properties of low-to moderate-current discharges in parallel-plane geometry. The time-dependent model assumes that the ion transit time is fixed and is short compared to the times of interest, that electrons are produced at the cathode only by ions, and that space-charge distortion of the electric field is small but not negligible. Illustrative numerical solutions are given for large voltage and current changes and analytic solutions for the time dependence of current and voltage are obtained in the small-signal limit. The small-signal results include the frequency and damping constants for decaying oscillations following a voltage change or following the injection of photoelectrons. The conditions for underdamped, overdamped, and self-sustained or growing oscillations are obtained. A previously developed steady-state, nonequilibrium model for low-pressure hydrogen discharges that includes the effects of space-charge distortion of the electric field on the yield of electrons at the cathode is used to obtain the negative differential resistance. Analytic expressions for the differential resistance and capacitance are developed using the steady-state, local-equilibrium model for electron and ion motion and a first-order perturbation treatment of space-charge electric fields. These models generally show good agreement with data from dc and pulsed discharge experiments presented in the accompanying papers.PACS number(s): 52.80.Dy, 52.80.Hc, 52.40.Hf

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“…Finally, it is assumed that the total current and the ion current are related by J t /j i = 1 + γ ef f , where γ ef f is effective value of the electron yield per ion arriving at the cathode [10,84]. The solution to (B.1) can now be expressed as…”

Section: Appendix B Space Charge Effectsmentioning

confidence: 99%

Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H₂

Phelps

2011

Plasma Sources Sci. Technol.

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Abstract.A model of the collisional kinetics of energetic hydrogen atoms, molecules, and ions in pure H 2 discharges is used to predict H α emission profiles and spatial distributions of emission from the cathode regions of low-pressure, weakly-ionized discharges for comparison with a wide variety of experiments. Positive and negative ion energy distributions are also predicted. The model developed for spatially uniform electric fields and current densities less than 10 −3 A/m 2 is extended to non-uniform electric fields, current densities of 10 3 A/m 2 , and electric field to gas density ratios E/N = 1. , and H − ions, fast H atoms, and fast H 2 molecules, and with reflection, excitation, and attachment to fast H atoms at surfaces. The H α excitation and H − formation occur principally by collisions of fast H, fast H 2 , and H + with H 2 . Model simplifications include using a one-dimensional geometry, a multi-beam transport model, and the average cathode-fall electric field. The H α emission is linear with current density over eight orders of magnitude. The calculated ion energy distributions agree satisfactorily with experiment for H + 2 and H + 3 , but are only in qualitative agreement for H + and H − . The experiments successfully modelled range from short-gap, parallel-plane glow discharges to beamlike, electrostatic-confinement discharges.

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Absolute measurement of low-energy H0 fluxes by a secondary emission detector

Cited by 51 publications

References 17 publications

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Oscillations of low-current electrical discharges between parallel-plane electrodes. III. Models

Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H₂

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Absolute measurement of low-energy H0 fluxes by a secondary emission detector

Cited by 51 publications

References 17 publications

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

Oscillations of low-current electrical discharges between parallel-plane electrodes. III. Models

Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H2

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Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H₂