Effect of reaction products kinetic on stability of thermonuclear spark ignition

• Published in: Journal of physics. Conference series Vol. 1009; no. 1; pp. 12011 - 12018
• Main Authors: Mikulin, A Yu, Glazyrin, S I, Kuratov, S E
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.04.2018
• Subjects: Distribution functions; Fokker-Planck equation; Momentum transfer; Parameters; Perturbation; Physics; Reaction products; Relaxation time; Spark ignition; Stability; Transport equations
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1009/1/012011

Thermonuclear spark instability driven by reaction products momentum transfer is considered in this paper. General theory of such instability was developed by Lykov [1] based on one-group particles transport equation solving. Main dimensionless parameter of this problem is l/λ, where λ is the perturbation wavelength and l is the reaction product mean free path. In two limiting cases of l/λ ratio we recalculated perturbations growth rates in a more precise manner, obtaining reaction products distribution function through Fokker-Planck equation. While our results are generally consistent with those of Lykov's work, instability growth rates predicted in this investigation are somewhat smaller than the previously reported values. By performing a sequence of hybrid kinetic-fluid simulations in code FRONT3D, we demonstrate their better agreement with our asymptotic predictions. However, it was shown that in a wide range of l/λ ratio the instability growth rates are well described by Lykov's theory. We apply Champan-Enskog method to describe plasma ions deviations away from Maxwellian distributions, which appears from interaction with higly non-maxwellian reaction products. We derive an equation, that connects concentration of non-equilibrium particles with such parameters as ion momentum relaxation time and reaction rate. As it was shown, for typical ICF parameters, non-equilibrium part does not exceed several percents even at the burn peak.