Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel
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 effec...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2004-09-01
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| Series: | Physical Review Special Topics. Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevSTAB.7.093202 |
| _version_ | 1818840417972518912 |
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| author | Arthur W. Molvik Michel Kireeff Covo Frank M. Bieniosek Lionel Prost Peter A. Seidl David Baca Adam Coorey Akira Sakumi |
| author_facet | Arthur W. Molvik Michel Kireeff Covo Frank M. Bieniosek Lionel Prost Peter A. Seidl David Baca Adam Coorey Akira Sakumi |
| author_sort | Arthur W. Molvik |
| collection | DOAJ |
| description | 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 γ_{e} scale as 1/cos(θ) up to angles of 86°, where γ_{e}=90. Nearer grazing incidence, γ_{e} is reduced below the 1/cos(θ) scaling by nuclear scattering of ions through large angles, reaching γ_{e}=135 at 88°. Electrons were emitted with a measured temperature of ∼30 eV. Gas desorption coefficients γ_{0} were much larger, of order γ_{0}=10^{4}. They also varied with angle, but much more slowly than 1/cos(θ). 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. |
| first_indexed | 2024-12-19T04:09:52Z |
| format | Article |
| id | doaj.art-cd3356b20d02473ab4700ebe753d4ffa |
| institution | Directory Open Access Journal |
| issn | 1098-4402 |
| language | English |
| last_indexed | 2024-12-19T04:09:52Z |
| publishDate | 2004-09-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Special Topics. Accelerators and Beams |
| spelling | doaj.art-cd3356b20d02473ab4700ebe753d4ffa2022-12-21T20:36:27ZengAmerican Physical SocietyPhysical Review Special Topics. Accelerators and Beams1098-44022004-09-017909320210.1103/PhysRevSTAB.7.093202Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steelArthur W. MolvikMichel Kireeff CovoFrank M. BieniosekLionel ProstPeter A. SeidlDavid BacaAdam CooreyAkira SakumiGas 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 γ_{e} scale as 1/cos(θ) up to angles of 86°, where γ_{e}=90. Nearer grazing incidence, γ_{e} is reduced below the 1/cos(θ) scaling by nuclear scattering of ions through large angles, reaching γ_{e}=135 at 88°. Electrons were emitted with a measured temperature of ∼30 eV. Gas desorption coefficients γ_{0} were much larger, of order γ_{0}=10^{4}. They also varied with angle, but much more slowly than 1/cos(θ). 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.http://doi.org/10.1103/PhysRevSTAB.7.093202 |
| spellingShingle | Arthur W. Molvik Michel Kireeff Covo Frank M. Bieniosek Lionel Prost Peter A. Seidl David Baca Adam Coorey Akira Sakumi Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel Physical Review Special Topics. Accelerators and Beams |
| title | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| title_full | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| title_fullStr | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| title_full_unstemmed | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| title_short | Gas desorption and electron emission from 1 MeV potassium ion bombardment of stainless steel |
| title_sort | gas desorption and electron emission from 1 mev potassium ion bombardment of stainless steel |
| url | http://doi.org/10.1103/PhysRevSTAB.7.093202 |
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