The effects of incident electron current density and temperature on the total electron emission yield of polycrystalline CVD diamond

Belhaj, Mohamed; Tondu, Thomas; Inguimbert, Virginie; Barroy, Pierre; Silva, François; Gicquel, A.

doi:10.1088/0022-3727/43/13/135303

Cited by 21 publications

(7 citation statements)

References 27 publications

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“…Diamond is another perspective material for high NI surface production rate 9 . It is well known for its ability to emit electrons at high temperature and even at low electric fields 21 . Beam experiments on diamond showed surface production of H − ions with high yields up to 5.5% 22 (yield is defined in these experiments as the negative ion fraction in the reflected particle flux).…”

Section: Methodsmentioning

confidence: 99%

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

Achkasov

Moussaoui

Kogut

et al. 2019

Journal of Applied Physics

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In this work negative-ion production on the surface of a sample negatively DC biased in a hydrogen plasma is studied. The negative ions created under the positive ion bombardment are accelerated towards the plasma, self-extracted and detected according to their energy and mass, by a mass spectrometer placed in front of the sample. The use of a pulsed bias allows applying a quasi-DC bias on insulating material during a short period of time and offers the possibility to extend the measurement method to nonconductive samples. The pulsed-bias tests were performed first with Highly Oriented Pyrolitic Graphite (HOPG), a conductive material, to demonstrate the feasibility of the method. By changing the pulsedbias frequency it was possible to obtain HOPG material with different hydrogen surface coverages and hence different surface states leading to an increase of negative-ion production by up to 30-50% as compared to the continuous bias case. To establish a protocol for insulating materials, charge accumulation on the surface during the bias pulse and influence of the bias duration and frequency were explored using microcrystalline diamond (MCD) thin layers. By using a pulse short enough (10 µs) at 1 kHz frequency, it has been possible to measure negative-ions on MCD sample at a quasi-constant surface bias of 130 V, with only 1 V variation during the measurement. Negative-ion surface production on MCD has been studied in pulsed mode with surface temperature from room temperature to 800°C. It is shown that pulsing the bias and increasing the temperature allows limiting defect creation on MCD which is favorable for negative-ion production. Consequently, at 400°C the yield on MCD in pulsed mode is one order of magnitude higher than the yield on HOPG in continuous mode at room temperature.

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Section: Methodsmentioning

confidence: 99%

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

Achkasov

Moussaoui

Kogut

et al. 2019

Journal of Applied Physics

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“…The TEY was measured at ALCHIMIE/DEESSE using a charge collection method with a pulsed electron beam, which has been proven to avoid charging effects and consequently enables an accurate measurement of the electron emission yield of insulators at low energies. The method and setup employed in this work were described in detail by Belhaj et al (2010). The schematic of the setup is presented in figure 1(a).…”

Section: See Measurementsmentioning

confidence: 99%

“…In this paper, we extended the low energy SEE studies to a-Si:H and ALD-deposited Al 2 O 3 . A setup presented by Belhaj et al (2010), highly suitable for TEY measurements from non-conductive surfaces, was used to determine the previously unknown TEY of a-Si:H and Al 2 O 3 surfaces for energies below 100 eV. In addition, the energy spectra of emitted electrons from the same surfaces for primary electron energies below 200 eV were measured using a setup particularly designed for such purposes by Villemant et al (2017).…”

Section: Introductionmentioning

confidence: 99%

A comprehensive analysis of electron emission from a-Si:H/Al₂O₃ at low energies

Löffler¹,

Belhaj²,

Bundaleski³

et al. 2023

J. Phys. D: Appl. Phys.

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Recently developed microchannel plates based on amorphous silicon offer potential advantages with respect to glass based ones. In this context, secondary electron emission at very low energies below 100 eV has been studied for relevant materials for these novel devices. The aim of this work was to quantify the low energy electron emission - secondary emission and elastic scattering - from amorphous silicon and alumina and the dependence of the emission energy distribution on the primary electron energy, which was previously unknown. Secondary emission and energy distribution were both modelled and measured using equipment particularly designed for this energy range. The effects of roughness, angle of incidence and surface composition were analysed. We show crossover energies as well as the angular dependence of electron emission from amorphous silicon and alumina, with a maximum experimental emission yield value of 2 and 2.8, respectively, at an incident angle of 75°. A parameterization for the energy dependence of the emission energy spectrum at low energies was derived. This extensive analysis is fundamental for a comprehensive understanding of the performance of amorphous silicon-based microchannel plate detectors. It provides a complete model for secondary electron emission for a detailed description of the detector operation. The present results thus set the basis for a simulation framework, which is an essential element to increase the performance of these detectors and enable further developments.

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“…The initial dust potential was thus -45 Volts. This technique is quite similar to the classical ones used for secondary electron emission measurement to reduce the backflow of repelled electrons where a positively biased hemispherical cup is placed above the sample [13]. The potential measured after VUV irradiation is -33 V with respect to chamber ground.…”

Section: A Experimental Setupmentioning

confidence: 99%

Multiscale Modeling of Dust Charging in Simulated Lunar Environment Conditions

Oudayer

Monnin

Matéo‐Vélez

et al. 2019

IEEE Trans. Plasma Sci.

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A key aspect of dust adhesion to space equipment is the accumulation of charge under the space plasma environment. Recent models and experiments show possible negative charging of dust grains under VUV illumination. Macroscopic potential measurements conducted during a test campaign show that both positive and negative average charging can be reached under VUV irradiation pending on vacuum chamber configuration, suggesting that both situations can exist at lunar surface. Simulations of dust charging at microscopic scale are conducted with the SPIS software to evaluate electrical charge and electric field amplifications induced by the granular structure of the lunar regolith. A multi-layer pile of dust is modelled under lunar conditions. Grains from the first two layers tend to microscopically acquire both negative and positive charge patches when illuminated with a 45° VUV incidence angle, this differential charging being less pronounced under normal incidence angle. It is also found that dust deeply buried in the lunar soil may charge more negative due to the collection of environmental electron only. This effect is thought to reinforce the grain supercharging model presented by other authors. We show however that such charge development may be limited by electrical conduction pending on dust electrical properties.Index Terms-dust lofting, lunar dust, electrical charge.

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The effects of incident electron current density and temperature on the total electron emission yield of polycrystalline CVD diamond

Cited by 21 publications

References 27 publications

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

A comprehensive analysis of electron emission from a-Si:H/Al₂O₃ at low energies

Multiscale Modeling of Dust Charging in Simulated Lunar Environment Conditions

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The effects of incident electron current density and temperature on the total electron emission yield of polycrystalline CVD diamond

Cited by 21 publications

References 27 publications

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

Pulsed DC bias for the study of negative-ion production on surfaces of insulating materials in low pressure hydrogen plasmas

A comprehensive analysis of electron emission from a-Si:H/Al2O3 at low energies

Multiscale Modeling of Dust Charging in Simulated Lunar Environment Conditions

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A comprehensive analysis of electron emission from a-Si:H/Al₂O₃ at low energies