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Anomalous enhancements of low-energy fusion rates in plasmas: the role of ion momentum distributions and inhomogeneous screening

100%

Coraddu M., Lissia M., Quarati P.

Open Physics

2009

vol. 7

issue 3

527-533

Non-resonant fusion cross-sections significantly higher than corresponding theoretical predictions are observed in low-energy experiments with deuterated matrix target. Models based on thermal effects, electron screening, or quantum-effect dispersion relations have been proposed to explain these anomalous results: none of them appears to satisfactory reproduce the experiments. Velocity distributions are fundamental for the reaction rates and deviations from the Maxwellian limit could play a central role in explaining the enhancement. We examine two effects: an increase of the tail of the target Deuteron momentum distribution due to the Galitskii-Yakimets quantum uncertainty effect, which broadens the energy-momentum relation; and spatial fluctuations of the Debye-Hückel radius leading to an effective increase of electron screening. Either effect leads to larger reaction rates especially large at energies below a few keV, reducing the discrepancy between observations and theoretical expectations.

Generalized model for the nonlinear dynamics of plasma waves driven unstable by energetic ions near the stability threshold

88%

Galant G.

Open Physics

2013

vol. 11

issue 11

1598-1604

In this paper, an attempt to develop the original single mode theory describing the nonlinear dynamics of a linearly unstable plasma wave, excited by the resonant interaction with energetic ions near the stability threshold to the case of n interacting plasma modes has been made. The effects of an energetic ion source and classical collisional processes represented by the Krook, diffusion and dynamical friction (drag) collision operators are included in the model. For numerical purposes, the problem has been reduced to ten nonlinearly coupled integro-differential equations. In comparison to the previous papers, the system revealed similar (the steady-state, oscillation, and blow-up solutions), as well as quite new types of the amplitudes behaviour, i.e. different levels of competition between the modes.

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2 Open Physics

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1 2009

1 Coraddu M.

1 Galant G.

1 Lissia M.

1 Quarati P.

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Anomalous enhancements of low-energy fusion rates in plasmas: the role of ion momentum distributions and inhomogeneous screening

Generalized model for the nonlinear dynamics of plasma waves driven unstable by energetic ions near the stability threshold