Ignition by shock wave focusing and staging of thermonuclear microexplosions

Abstract

FROM the beginning of laser fusions research¹ the main problem has been the very large size of the ignition apparatus. For this reason relativistic electron beams² and, more recently, ion beams³ have been proposed as alternatives. Relativistic electron beams have the following principal problems, however, when compared with laser beams: first the pulse length is rather long, and second the beam focusing is not as good. Ion beams are not as easily focused as either laser or electron beams. Furthermore, in both laser- and electron-beam induced implosion most of the energy goes into the ablation products, rather than the thermonuclear target. I propose here an alternative, non-ablative energy deposition method, applicable to laser, electron or ion beams, and which has the following distinct advantages: (1) The energy is delivered to the target by a shock wave. (2) The beam energy can be focused precisely on the target. (3) The energy pulse length can be shortened by about an order of magnitude. (4) The method permits staging, whereby a small microexplosion can set off a larger one.