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6CCVD Research

Boron and phosphorus doped diamond - change in the electronic structure post exposure to low pressure deuterium plasma and its effect on the production of negative ions

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2025-03-19
JournalJournal of Physics D Applied Physics
AuthorsR.J. Magee, M.A. Pinault-Thaury, Jocelyn Achard, Jean-Marc Layet, D. Guyomarc’h
InstitutionsGroupe d’Étude de la MatiĂšre CondensĂ©e, University of York

Abstract

Section titled “Abstract”

Abstract Negative ion production is of significant interest for materials processing and neutral beam injection systems for magnetic confinement fusion reactors. The surface production mechanism can be required for high current applications. Dielectric materials, including doped diamond, are of interest for increasing surface production as a potential alternative to low-work function metals and further understanding of the underpinning mechanisms is needed. In this study we use photoemission yield spectroscopy, in conjunction with the Fowler model and mass spectrometry, to measure the negative ion yield and ionization threshold of micro-crystalline diamond ( ” c-D), micro-crystalline boron doped diamond ( ” c-BDD) and single crystal phosphorus doped diamond (PDD) under deuterium plasma exposure at sample temperatures between 30 ∘ C and 700 ∘ C. We observe that deuterium plasma exposure of PDD at 400 ∘ C reduces its ionization threshold from approximately 4.0 eV to 2.1 eV, which is similar to the work function of cesium. While the ionization threshold of diamond is observed to be sensitive to sample temperature and the dopant used, this appears to have negligible effect on negative ion production. Developing a better understanding of which material properties are most significant for negative ion production will assist the development of improved negative ion sources.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2009 - High-energy negative ion beam obtained from pulsed inductively coupled plasma for charge-free etching process [Crossref]
  2. 2013 - Plasma etching: yesterday, today and tomorrow [Crossref]
  3. 2010 - Interesting experimental results in Japan proton accelerator research complex H− ion-source development (invited) [Crossref]
  4. 2000 - Negative ion sources for high energy accelerators (invited) [Crossref]
  5. 2005 - Negative hydrogen ion sources for accelerators [Crossref]
  6. 2018 - An overview of negative hydrogen ion sources for accelerators [Crossref]
  7. 2016 - Brief review on plasma propulsion with neutralizer-free systems [Crossref]
  8. 2015 - Alternate extraction and acceleration of positive and negative ions from a gridded plasma source [Crossref]
  9. 2015 - The PEGASES gridded ion-ion thruster performance and predictions [Crossref]
  10. 2020 - Achievement of the ITER NBI ion source parameters for hydrogen at the test facility ELISE and present Status for deuterium [Crossref]

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