Penetration and energy-loss theory of electrons in solid targets

Abstract

Starting from a simple atomic model giving the potential between electrons and atoms as V(r) = Ze 2 a s−1/sr s with the empirical value s=fraction six-fifths, we combine the diffusion effect due to multiple collisions and the energy retardation in accordance with a modified Thomson-Whiddington law, with the scattering cross section in the Lenard absorption law. On this basis, consistent expressions are obtained for the fraction of transmitted electrons in amorphous solid targets, the backscattering fraction with depth, the fraction of electrons absorbed per unit mass-thickness and the depth-dose function, which are in good agreement with experiments over the energy range 10-1000 keV. A diffusion model represented by a sphere whose centre is located at the maximum energy dissipation depth, related to the diffusion depth and the range, is found to agree well with experiments.

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

“…It has been shown that the first crossover energy (where the SEY increases above 1) is strongly dependent on the surface properties whereas the energy at maximum yield is entirely controlled by bulk properties [29]. The escape depth for the true secondary is about 50 nm [30], so in order to decrease the SEY of an existing material using any of these parameters becomes a very difficult task and it has only been achieved by coating with a low SEY material [31]. The alternative method to lower the SEY is to trap the secondary emitted electron via the surface geometry such as high aspect ratio grooves [32] and surfaces covered by thin films [33].…”

Runaway generation during disruptions in JET and TEXTOR

“…This value varies between 2 ms and 5 ms for JET runaway disruptions (figure 5). The penetration depth in Be and C is 2.5 mm and 2.0 mm, respectively [18]. The penetration in W is 0.15 mm.…”

Growth and characterization of wurtzite InP/AlGaP core–multishell nanowires with AlGaP quantum well structures

“…Cathodoluminescence (CL) measurements were performed at 34 K on a single CMS NW with an acceleration voltage of 7 kV. Based on the calculation by Kanaya et al, 19) the penetration depth of the electrons was about 500 nm under this condition, whereas most of the electrons were generated within a fraction of the penetration depth. 2(f), the aluminum and gallium compositions in the barrier layers were almost the same excluding the effect of indium diffusion, which is equal to the supply ratio of TMAl and TMGa.…”