Excitation of Electrons in Solids by Relatively Slow Atomic Particles

Abroyan, I.A.; Eremeev, M A; Petrov, N. N.

doi:10.1070/pu1967v010n03abeh003250

Cited by 36 publications

(15 citation statements)

References 2 publications

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“…These electrons sustain the discharge by ionization of the neutral gas, and generation of ions which then bombard the cathode releasing more secondary electrons. Ion-and neutral-induced secondary electron emission has been studied both theoretically and experimentally for decades (Abroyan et al, 1967;Hasselkamp, 1992;Parilis and Kishinevskii, 1960).…”

Section: B Secondary Electronsmentioning

confidence: 99%

Foundations of DC plasma sources

Guðmundsson

Hecimovic

2017

Plasma Sources Sci. Technol.

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A typical dc discharge is configured with the negative cathode at one end and a positive anode at the other end, separated by a gas filled gap, placed inside a long glass cylinder. A few hundred volts between the cathode and anode is required to maintain the discharge. The type of discharge that is formed between the two electrodes depends upon the pressure of the working gas, the nature of the working gas, the applied voltage and the geometry of the discharge. We discuss the current-voltage characteristics of the discharge as well as the distinct structure that develops in the glow discharge region. The dc glow discharge appears in the discharge current range from µA to mA at 0.5 -300 Pa pressure. We discuss the various phenomena observed in the dc glow discharge, including the cathode region, the positive column, and striations. The dc glow discharge is maintained by the emission of secondary electrons from the cathode target due to the bombardment of ions. For decades the dc glow discharge has been used as a sputter source. Then it is often operated as an obstructed abnormal glow discharge and the required applied voltage is in the range 2 -5 kV. Typically, the cathode target (the material to be deposited) is connected to a negative voltage supply (dc or rf) and the substrate holder faces the target. The relatively high operating pressure, in the range from 2 -4 Pa, high applied voltages, and the necessity to have a conductive target limit the application of dc glow discharge as a sputter source. In order to lower the discharge voltage and expand the operation pressure range the lifetime of the electrons in target vicinity is increased through applying magnetic field, by adding permanent magnets behind the cathode target. This arrangement is coined the magnetron sputtering discharge. The various configurations of the magnetron sputtering discharge and its applications are described. Furthermore, the use of dc discharges for chemical analysis, the Penning discharge and the hollow cathode discharges and some of its applications are briefly discussed.

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Section: B Secondary Electronsmentioning

confidence: 99%

Foundations of DC plasma sources

Guðmundsson

Hecimovic

2017

Plasma Sources Sci. Technol.

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“…Ion-induced electron emission (IIEE) can be theoretically split into two distinct processes [47,48]: (i) kinetic electron emission quantified by a yield γ k , which is the ionic counterpart of secondary electron emission, where the energy required for the bound electron excitation is provided by the kinetic energy of the impinging ions; (ii) potential electron emission quantified by a yield γ p , where the energy required for the bound electron excitation is provided by the potential energy released during the neutralization of the impinging ions. There is an incident energy threshold E th inc below which kinetic electron emission cannot occur.…”

Section: Updates Of Plasma-surface Interactionsmentioning

confidence: 99%

Survival and in-vessel redistribution of beryllium droplets after ITER disruptions

et al. 2018

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The motion and temperature evolution of beryllium droplets produced by first wall surface melting after ITER major disruptions and vertical displacement events mitigated during the current quench are simulated by the MIGRAINe dust dynamics code. These simulations employ an updated physical model which addresses droplet-plasma interaction in ITER-relevant regimes characterized by magnetized electron collection and thin-sheath ion collection, as well as electron emission processes induced by electron and high-Z ion impacts. The disruption scenarios have been implemented from DINA simulations of the time-evolving plasma parameters, while the droplet injection points are set to the first-wall locations expected to receive the highest thermal quench heat flux according to field line tracing studies. The droplet size, speed and ejection angle are varied within the range of currently available experimental and theoretical constraints, and the final quantities of interest are obtained by weighting single-trajectory output with different size and speed distributions. Detailed estimates of droplet solidification into dust grains and their subsequent deposition in the vessel are obtained. For representative distributions of the droplet injection parameters, the results indicate that at most a few percents of the beryllium mass initially injected is converted into solid dust, while the remaining mass either vaporizes or forms liquid splashes on the wall. Simulated in-vessel spatial distributions are also provided for the surviving dust, with the aim of providing guidance for planned dust diagnostic, retrieval and clean-up systems on ITER.

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“…Toutefois, l'utilisation de cibles solides et l'observation' d'électrons introduisent quelques différences. Tout d'abord, avant qu'il atteigne la cible, l'ion A+ est généralement neutralisé par transition résonnante ou par neutralisation Auger [17], car la vitesse de l'ion incident A+ est suffisamment faible pour permettre à un électron de conduction du métal cible de passer sur un niveau électronique inoccupé de l'ion incident, avec éventuellement émission potentielle d'électrons secondaires [18,19]. C'est donc un atome d'argon neutre qui atteint la cible.…”

Section: Introduction -En 1965 Fano Etunclassified

“…D'une part, la forme du spectre Auger de l'argon ne dépend pas de l'angle d'émission des électrons ; d'autre part, l'intensité de l'émission varie avec l'angle d'émission selon une loi en cosinus ( Fig. 2), identique à celle obtenue lors du bombardement de métaux polycristallins pour l'émission des électrons secondaires [19,35] et pour l'émission Auger des atomes du métal [7]. La majeure partie des désexcitations Auger observées ont donc lieu à l'intérieur du métal, et les désexcitations externes, qui conduiraient à une émission Auger isotrope, ne peuvent jouer qu'un rôle négligeable.…”

Section: Introduction -En 1965 Fano Etunclassified

Émission Auger de l'argon lors du bombardement de divers métaux par des ions A+

Lesegno¹,

Hennequin²

1974

J. Phys. France

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place du 8 mai 1945, 93206 Saint-Denis, France (Reçu le 25 mars 1974) Résumé. 2014 Les conditions d'observation d'électrons Auger émis par l'argon lors du bombardement de cibles solides par des ions A+ sont étudiées et précisées dans le cas de métaux (K, Ca, Sc, Ti, V, Cr) bombardés par des ions A+ jusqu'à une énergie de 15 keV. L'énergie des ions A+ doit dépasser une énergie seuil qui dépend de la cible et qui est de l'ordre d'une dizaine de keV pour les métaux étudiés. Comme pour des collisions en phase gazeuse, ces conclusions s'interprètent par la possibilité de transitions électroniques aux croisements des orbitales moléculaires formées au cours de la collision. Abstract. 2014 The conditions for Auger electron emission from argon during ion bombardment of solid targets by Ar+ ions are studied for the case of metals (K, Ca, Sc, Ti, V, Cr) bombarded by Ar+ ions at energies lower than 15 keV. The Ar+ ion energy must exceed a threshold value which depends on the target and is of the order of 10 keV for the metals studied. Analogous to gaseous collisions, the results indicate that electronic transitions are effective at crossings of the molecular orbitals created during the collision.

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Excitation of Electrons in Solids by Relatively Slow Atomic Particles

Cited by 36 publications

References 2 publications

Foundations of DC plasma sources

Foundations of DC plasma sources

Survival and in-vessel redistribution of beryllium droplets after ITER disruptions

Émission Auger de l'argon lors du bombardement de divers métaux par des ions A+

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