A liquid hydrocarbon deuteron source for neutron generators

Experimental studies of a deuteron spark source for neutron generators using hydrogen isotope fusion reactions are reported. The ion source uses a spark discharge between electrodes coated with a deuterated hydrocarbon liquid, here Santovac 5, to inhibit permanent electrode erosion and extend the li...

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Bibliographic Details
Published in:Journal of applied physics 2017-06, Vol.121 (21)
Main Author: Schwoebel, P. R.
Format: Article
Language:English
Subjects:
Coated electrodes
Deuteration
Deuterium
Electric sparks
Emission spectra
Erosion
Generators
H alpha line
Hydrocarbons
Hydrogen
Hydrogen isotopes
Hydrogen storage
Ion sources
Mass spectra
Residual gas
Swan bands
Vacuum chambers
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Summary:Experimental studies of a deuteron spark source for neutron generators using hydrogen isotope fusion reactions are reported. The ion source uses a spark discharge between electrodes coated with a deuterated hydrocarbon liquid, here Santovac 5, to inhibit permanent electrode erosion and extend the lifetime of high-output neutron generator spark ion sources. Thompson parabola mass spectra show that principally hydrogen and deuterium ions are extracted from the ion source. Hydrogen is the chief residual gas phase species produced due to source operation in a stainless-steel vacuum chamber. The prominent features of the optical emission spectra of the discharge are C+ lines, the hydrogen Balmer Hα -line, and the C2 Swan bands. Operation of the ion source was studied in a conventional laboratory neutron generator. The source delivered an average deuteron current of ∼0.5 A nominal to the target in a 5 μs duration pulse at 1 Hz with target voltages of −80 to −100 kV. The thickness of the hydrocarbon liquid in the spark gap and the consistency thereof from spark to spark influences the deuteron yield and plays a role in determining the beam-focusing characteristics through the applied voltage necessary to break down the spark gap. Higher breakdown voltages result in larger ion beam spots on the target and vice-versa. Because the liquid self-heals and thereby inhibits permanent electrode erosion, the liquid-based source provides long life, with 104 pulses to date, and without clear evidence that, in principle, the lifetime could not be much longer. Initial experiments suggest that an alternative cylindrical target-type generator design can extract approximately 10 times the deuteron current from the source. Preliminary data using the deuterated source liquid as a neutron-producing target are also presented.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4984585