Equilibrium Ignition, a Minimum Energy Route to Fusion Via Multiple Mass Shell Collisions

Abstract

It is suggested that the minimum energy route to inertial fusion ignition is where the density of fuel and confining material is sufficiently high that the heat of the thermonuclear fuel can be contained at equilibrium conditions at ignition temperature with negligible penalty of thermal heat loss. Naturally the period of this confinement is established by the "inertial" conditions, but it is found that the scaling of reaction rate and thermal confinement time strongly favors thermal equilibrium conditions within the fuel rather than the standard model where higher temperatures allow the energy production reaction rate to exceed the radiation (bremstralhung) loss rate. Because of the high penalty of the energy within the confinement medium, the "pusher", (~ ×5 that of the fuel), there is a high premium in maintaining the "adiabat" of the high density confining material as close to Fermi degeneracy, i.e., cold, as possible. Furthermore, because of this requirement for a cold adiabat, an efficient route from stored electrical energy, i.e., capacitors, to ignition is suggested. The stable and efficient acceleration of a thin metal shell, a "liner" to modest velocities, ~ 0.5 cm/¿s by the magnetic field of the current of capacitor discharge, has been well documented for relatively modest rise times of the current, ~ 5 ¿s. Multiple high density cylindrical mass shells, e.g.