Coaxial Ion Source : pressure dependence of gas flow and field ion emission

We investigated the pressure dependence of gas flow and field ion intensity of a coaxial ion source operating at room temperature over a wide pressure range, testing various gases and ionisation voltages. Flow conductance measurements taking into account the different gases' viscosity and molec...

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Bibliographic Details
Published in:arXiv.org 2023-05
Main Authors: Bedrane, Djouher, Houel, Arnaud, Delobbe, Anne, Lagaize, Mehdi, Dumas, Philippe, Veesler, Stéphane, Salançon, E
Format: Article
Language:English
Subjects:
Emission analysis
Field ionization
Gas flow
Gases
Ion currents
Ion emission
Ion sources
Low pressure
Partial pressure
Pressure chambers
Pressure dependence
Room temperature
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Summary:We investigated the pressure dependence of gas flow and field ion intensity of a coaxial ion source operating at room temperature over a wide pressure range, testing various gases and ionisation voltages. Flow conductance measurements taking into account the different gases' viscosity and molecular mass consistently exhibit a generic pattern. Three different flow regimes appear with increasing upstream pressure. Since the coaxial ion source supplies the gas locally, very near the apex of the tip where ionisation occurs, large ionisation currents can be obtained without degrading the propagation conditions of the beam. Compared with field ionisation in a partial pressure chamber, using the coaxial ion source increases the ion current a hundredfold for the same residual low pressure. We also show that the gas flow regime does not impact ionisation yield. Although a fuller characterisation remains to be performed, brightness reaches 3 x 10 11 A/m 2 /sr at 12kV extracting voltage. a) https://www.cinam.univ-mrs.fr/
ISSN:2331-8422
DOI:10.48550/arxiv.2305.05297