Document Type

Article

Publication Date

2025

DOI

10.1116/6.0004987

Publication Title

Journal of Vacuum Science & Technology B

Volume

43

Issue

6

Pages

064204 (1-19)

Abstract

The outgassing properties of bare and magnetite-coated AISI 1020 low-carbon steel vacuum chambers were evaluated to establish material selection criteria for extreme high vacuum applications, namely, to explore the possibility of using these materials to build next-generation spin-polarized photoelectron guns. Water outgassing measurements using the throughput method revealed that the magnetite-coated chamber exhibited five times lower outgassing at room temperature prior to baking, but this advantage disappears after 80 °C baking. Hydrogen outgassing measurements demonstrated significant differences after intensive heat treatment: the bare low-carbon steel vacuum chamber achieved a specific outgassing rate of 9.6 × 10−16 Torr L s−1 cm−2 after 400 °C/50 h bake plus additional heat treatment at lower temperatures, 25 times lower than the magnetite-coated low-carbon steel chamber. Residual gas analysis showed >99% hydrogen composition after heat treatment for both materials, with carbon species below detection limits for bare low-carbon steel versus 0.8% for magnetite-coated surfaces. These measurements indicate that properly conditioned bare low-carbon steel can achieve the < 10−12 Torr pressures required for next-generation spin-polarized photogun applications. The paper includes various analysis techniques intended to explain observed behaviors: isotherm analysis of pump-down plots, Arrhenius analysis of hydrogen outgassing rate data, and residual gas composition tracking.

Rights

© Copyright 2026 AIP Publishing LLC.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in 

Al-Allaq, A. H., Mamun, M. A., Poelker, M., & Elmustafa, A. (2025). Outgassing measurements of bare and magnetite-coated low-carbon steel vacuum chambers. Journal of Vacuum Science & Technology B, 43(6), 1-19, Article 064204. 

and may be found at https://doi.org/10.1116/6.0004987

Data Availability

Article states: "The data that support the findings of this study are available from the corresponding author upon reasonable request."

Original Publication Citation

Al-Allaq, A. H., Mamun, M. A., Poelker, M., & Elmustafa, A. (2025). Outgassing measurements of bare and magnetite-coated low-carbon steel vacuum chambers. Journal of Vacuum Science & Technology B, 43(6), 1-19, Article 064204. https://doi.org/10.1116/6.0004987

ORCID

0000-0002-0415-2795 (Al-Allaq), 0000-0001-5865-6035 (Elmustafa)

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