The natural fit of cylindrical geometry to the long range of high energy heavy ions has been explored by eminent German and Russian physicists, including Jüergen Meyer-ter-Vehn at the Max Planck Institute in München and Michel Basko at ITEP in Moscow. The "hollow" beam to heat the annulus of a dense material like lead is produced by the RF "wobbler" developed by Golubev at ITEP.
The figure below illustrates FPC's conceptual improvements. The target is heated through both ends. This improves reliability (by eliminating a possible single-point failure) since fusion burn ignited at either end will propagate to all the compressed fuel. Compression beams from each end similarly increase reliability. Providing four beams to heat the target from each end (eight beams total), with each beam irradiating the entire mass to be heated, presents a "graceful degradation" scenario: a problem with one beam decreases the total heating by only 12%. The driver design will exceed requirements, to assure the resulting reliability.