Impact fusion and the field emission projectile

Abstract

A conceivable approach to the problem of achieving controlled thermonuclear power is by impact fusion^1–3. Small projectiles (macrons⁴), of mass ∼0.1 g and of appropriate material and design, are accelerated to a velocity v∼10⁸cms⁻¹; they then collide with a deuterium–tritium target, and their kinetic energy is abruptly converted into thermal energy (∼10keV per nucleon, temperature ∼10⁸ K) that is inertially confined in a shocked region. Preliminary studies^1,2 in the early 1960s showed that in these conditions the released nuclear energy exceeds the initial kinetic energy. Despite its attractiveness, relatively little research has been devoted to the development of impact fusion as a power-producing technology, and only recently⁵ have serious attempts been made to evaluate its importance compared with the more familiar proposed methods of magnetic and inertial confinement. The principal block to impact fusion is the development of accelerators capable of accelerating macrons to velocities two orders of magnitude greater than can be attained by existing methods. It is shown here, using general arguments, that the minimum length of such macron accelerators must exceed 1 km. A possible way of achieving the required high velocity is to accelerate, in a travelling electric field, macrons that are self-charged by electron field emission.