New preprint ---
"Investigation of light ion fusion reactions with plasma discharges"
ABSTRACT:
The scaling of reaction yields in light ion fusion to low reaction energies
is important for our understanding of stellar fuel chains and the development
of future energy technologies. Experiments become progressively more
challenging at lower reaction energies due to the exponential drop of fusion
cross sections below the Coulomb barrier. We report on experiments where
deuterium-deuterium (D-D) fusion reactions are studied in a pulsed plasma in
the glow discharge regime using a benchtop apparatus. We model plasma
conditions using particle-in-cell codes. Advantages of this approach are
relatively high peak ion currents and current densities (0.1 to several A/cm^2)
that can be applied to metal wire cathodes for several days. We detect neutrons
from D-D reactions with scintillator-based detectors. For palladium targets, we
find neutron yields as a function of cathode voltage that are over 100 times
higher than yields expected for bare nuclei fusion at ion energies below 2 keV
(center of mass frame). A possible explanation is a correction to the ion
energy due to an electron screening potential of 1000+/-250 eV, which increases
the probability for tunneling through the repulsive Coulomb barrier. Our
compact, robust setup enables parametric studies of this effect at relatively
low reaction energies.
