Ignition threshold for non-Maxwellian plasmas

Abstract

An optically thin $p$-${}^{11}$B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. The minimum Lawson criterion for thermal $p$-${}^{11}$B plasmas and the minimum $\rho R$ required for ICF volume ignition are calculated. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for this utility, we consider a monoenergetic beam with particle energy selected to maximize the beam- thermal reactivity. Channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and $\rho R$, improves reactivity at constant pressure, and could be used to remove helium ash. The gains realized with a beam thus establish an upper bound for the reductions in ignition threshold that can be realized with any nonthermal distribution; these are evaluated for $p$-${}^{11}$B and DT plasmas.

16 pages, 5 figures

References in corpus (1)

• Alpha Channeling in a Rotating Plasma

Cited by in corpus (8)

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• Fusion yield of plasma with velocity-space anisotropy at constant energy
• Confinement Time and Ambipolar Potential in a Relativistic Mirror-Confined Plasma
• Accelerator Based Fusion Reactor
• On extreme points of the diffusion polytope
• Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas