Measuring the secondary electron emission characteristic of insulators

Hopman, H. J.; Alberda, H.; Attema, I.; Zeijlemaker, H.; Verhoeven, J.

doi:10.1016/s0368-2048(03)00091-4

Cited by 32 publications

(15 citation statements)

References 14 publications

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“…This is achieved by alternating short electron pulses where r < 1 when the sample is positively charged and where r > 1 when the sample is negatively charged. [17][18][19] Note that the "as received" ceramics are usually charged before being exposed to electron beams and may in some cases exhibit a surface potential of tens to hundreds of volts (positive or negative). For instance, a positive surface potential of 67 V was measured on the BN-SiO 2 sample, whereas a negative surface potential of À49 V was measured on Al 2 O 3 .…”

Section: Methodsmentioning

confidence: 99%

Electron-emission yield under electron impact of ceramics used as channel materials in Hall-effect thrusters

Tondu¹,

Belhaj²,

Inguimbert³

2011

Journal of Applied Physics

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We report measurement of electron-emission yield (EEY) under the impact of electrons on materials of Hall-effect-thruster (HET) interest: BN, BN-SiO 2 , and Al 2 O 3 . The effects of the material aging (under electron irradiation) on the yield of BN and Al 2 O 3 are investigated. The EEY of BN grows with electron exposure, whereas that of Al 2 O 3 reduces. A simple analysis of our experimental results indicates that these variations are most likely because of surface and near surface composition changes caused by the electron beam. The representativeness of EEY measurements on ceramics that have not suffered from the specific environment of a HET (ion and electron bombardment) is discussed.

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Section: Methodsmentioning

confidence: 99%

Electron-emission yield under electron impact of ceramics used as channel materials in Hall-effect thrusters

Tondu¹,

Belhaj²,

Inguimbert³

2011

Journal of Applied Physics

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“…Most of the studies were focused only on the measurement of the energy dependence of the intrinsic SEE yield, σ 0 = f(E), that is the yield of the uncharged material. [13][14][15] For that it is necessary to maintain the surface potential close to zero in order to avoid the undesirable effect of charging on the emission of secondary electrons. As early as 1954, Bruining recommended the use of a pulse injection method.…”

Section: Introductionmentioning

confidence: 99%

“…17 Stranger enough, no intensive work on mica has been carried out in order to elucidate the reasons of its good dielectric properties. One of the most recent work on the subject is that of Hopman et al 13 who proposed a compensation pulse method by alternating the magnitude of the voltage applied to the sample in such a way that the surface positively charged for one pulse becomes negative for the next one. 13 This method presents a specific interest for our work since it was applied to mica.…”

Section: Introductionmentioning

confidence: 99%

The secondary electron emission yield of muscovite mica: Charging kinetics and current density effects

Blaise

Pesty

Garoche

2009

Journal of Applied Physics

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Using a dedicated Scanning Electron Microscope (SEM), operating in the spot mode, the charging properties of muscovite mica have been studied in the energy range 100-8000 eV. The intrinsic yield curve σ 0 (E), representing the variation of the yield of the uncharged material with the energy E, has been established: the maximum value of the yield is 3.92 at E = 300 eV and the two crossovers corresponding to σ 0 (E) = 1 are respectively at energies E I < 100 eV and E II = 4850 eV. At a given energy and under a low current density J ≤ 100 nA/cm 2 , the yield varies with the electron fluence from its intrinsic value σ 0 up to the value corresponding to the Self Regulated Regime (SRR) for which σ = 1. This variation is independent of J. The fluence dependence of the yield σ(D) is due to the internal field produced by the accumulation of charges that blocks the emission when the charging is positive and enhances it when it is negative. At room temperature, the relaxation time of stored charges is estimated to be of the order of 250 sec for holes and 150 sec for electrons. Three current density effects have been observed when J ≥ 400 nA/cm 2. (i) The variation of σ(D) with the fluence D depends on J. (ii) Negative charging is obtained at high current density in the energy range (E I ,E II) where the material is normally positively charged at low current density. (iii) Electron exo emission (bursts of electrons) is produced at low energy when the net stored charge is positive. The interpretation of the current density effect on σ(D) is based on the high rate of charging, the effect relative to negative charging is due to the expansion of the electron distribution, while the exoemission effect is due to the collective relaxation process of electrons.

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“…6,7 Many efforts have been made for charge neutralization and SEY measurement of insulators. [8][9][10][11][12][13][14][15][16][17][18][19][20] The measurement system with two electron guns could eliminate or weaken charge accumulation. [12][13][14][15] In addition to a pulsed electron gun for SEY measurement, the other low-energy (less than several eV) flood one was used to neutralize positive charges accumulated on the sample surface.…”

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confidence: 99%

“…Measurements based on a single pulsed electron gun were also reported. [16][17][18][19] Here, the PE energy E pe alternated for negative and positive charging, respectively, for charge compensation, and a Kelvin probe was simultaneously used to detect the potential variation at the sample surface so that positive charges could be effectively neutralized. These charge neutralization approaches are naturally sophisticated and of high cost, in spite of higher accuracy for SEY measurement.…”

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confidence: 99%

Note: A simple charge neutralization method for measuring the secondary electron yield of insulators

Weng

Cao

Zhao

et al. 2014

Review of Scientific Instruments

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We report on a simple and effective charge neutralization method for measuring the total electron-induced secondary electron yield of insulators in a measurement system with a single pulsed electron gun. In this method, the secondary electron collector is negatively biased with respect to the sample to force some emitted secondary electrons to return to the sample surface and therefore to neutralize positive charges accumulated in the sample during the previous measurement. The adequate negative bias is determined and the equilibrium state of negative charging is discussed. The efficacy of the method is demonstrated by the measured electron yields in the cases with and without charge neutralization and by comparison with existing electron yield data of polyimide.

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Measuring the secondary electron emission characteristic of insulators

Cited by 32 publications

References 14 publications

Electron-emission yield under electron impact of ceramics used as channel materials in Hall-effect thrusters

Electron-emission yield under electron impact of ceramics used as channel materials in Hall-effect thrusters

The secondary electron emission yield of muscovite mica: Charging kinetics and current density effects

Note: A simple charge neutralization method for measuring the secondary electron yield of insulators

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