| Article | |
| Title | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| Author(s) | Molvik, Arthur W (Lawrence Livermore National Laboratory, Livermore) ; Covo, Michel Kireeff (LBNL Berkeley) ; Bieniosek, Frank M (LBNL Berkeley) ; Prost, Lionel (LBNL Berkeley) ; Seidl, P (LBNL Berkeley) ; Baca, David (LBNL Berkeley) ; Coorey, Adam (LBNL Berkeley) ; Sakumi, Akira (CERN) |
| Publication | 2004 |
| In: | Phys. Rev. Spec. Top. Accel. Beams 7 (2004) 093202 |
| DOI | 10.1103/PhysRevSTAB.7.093202 |
| Subject category | Nuclear Physics |
| Abstract | Gas desorption and electron emission coefficients were measured for 1 MeV potassium ions incident on stainless steel at grazing angles (between 80° and 88° from normal incidence) using a new gas-electron source diagnostic (GESD). Issues addressed in design and commissioning of the GESD include effects from backscattering of ions at the surface, space-charge limited emission current, and reproducibility of desorption measurements. We find that electron emission coefficients e scale as 1/ cos() up to angles of 86°, where e = 90. Nearer grazing incidence, e is reduced below the 1/ cos() scaling by nuclear scattering of ions through large angles, reaching e = 135 at 88°. Electrons were emitted with a measured temperature of 30 eV. Gas desorption coefficients 0 were much larger, of order 0 = 104. They also varied with angle, but much more slowly than 1/ cos(). From this we conclude that the desorption was not entirely from adsorbed layers of gas on the surface. Two mitigation techniques were investigated: rough surfaces reduced electron emission by a factor of 10 and gas desorption by a factor of 2; a mild bake to 220° had no effect on electron emission, but decreased gas desorption by 15% near grazing incidence. We propose that gas desorption is due to electronic sputtering. |
| Copyright/License | Publication: (License: CC-BY-3.0) |
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Element opprettet 2005-06-25, sist endret 2018-09-24
