Performance of LaB6-Emitters for Neutral Gas Pressure Gauges During Plasma Operation in the Large Helical Device

With the aim of providing precise and reliable neutral gas pressure measurements in plasma experiments, several types of neutral gas pressure gauges using LaB6-emitters were tested at the Large helical device (LHD) during the last four experimental campaigns. A significant failure rate of the neutra...

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Bibliographic Details
Published in:IEEE transactions on plasma science 2024-09, Vol.52 (9), p.3511-3515
Main Authors: Haak, Victoria, Motojima, Gen, Jagielski, Bartholomaus, Naujoks, Dirk, Graband, Andreas, Pilopp, Dirk
Format: Article
Language:English
Subjects:
Annealing
boron compounds
cathodes
current measurement
deuterium
emission
Heating systems
lanthanum compounds
neutron radiation effects
Neutrons
Plasmas
Pressure gauges
Pressure measurement
Surface treatment
Thermionic emission
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Summary:With the aim of providing precise and reliable neutral gas pressure measurements in plasma experiments, several types of neutral gas pressure gauges using LaB6-emitters were tested at the Large helical device (LHD) during the last four experimental campaigns. A significant failure rate of the neutral gas pressure gauges could be observed. While the reasons are still unclear, correlations between the failure of LaB6-emitters and deuterium plasma operation with neutron generation have been discovered and are discussed here. Activation of the LaB6-emitters at a higher heating current than during standard operation was carried out during the campaign as an attempt to improve their thermionic emission properties and resulted in changes to the surface structure that were detected by scanning electron microscopy.
ISSN:0093-3813
DOI:10.1109/TPS.2024.3352688