For several more nanoseconds, this did not matter.

The plutonium was still increasing its reaction rate, still doubling, still increasing its Alpha at a rate only expressible numerically.

Energy was now flooding into the Secondary. The metallically-coated straws flashed to plasma, pressing inward on the Secondary. Radiant energy in quantities not found on the surface of the sun vaporized but also reflected off elliptical surfaces, delivering yet more energy to the Secondary assembly, called the Holraum. The plasma from the immolated straws pounded inward towards the second reservoir of lithium compounds. The dense uranium 238 fins just outside the Secondary pit also flashed to dense plasma, driving inward through the vacuum, then striking and compressing the tubular containment of more 238U around the central container which held the largest quantity of lithium-deuteride/tritium. The forces were immense, and the structure was pounded with a degree of pressure greater than that of a healthy stellar core.

But not enough.

The Primary's reaction had already slackened. Starved of neutrons by the presence of the 3He poison, the bomb's explosive force began to blow apart the reaction mass as soon as the physical forces reached their balance. The chain reaction reached a moment of stability, at last unable to sustain its geometric rate of growth; the last two chain-reaction doublings were lost entirely, and what should have been a total Primary yield of seventy thousand tons of TNT was halved, halved again, and in fact ended with a total yield of eleven thousand two hundred tons of high explosive.

Fromm's design had been as perfect as the circumstances and materials allowed. An equivalent weapon less than a quarter the size was possible, but his specifications were more than adequate. A massive safety factor in the energy budget had been planned for. Even a thirty kiloton yield would have been enough to ignite the 'sparkplug' in the Secondary to start a massive fusion 'burn,' but thirty-KT was not reached. The bomb was technically called a 'fizzle.'

But it was a fizzle equivalent to eleven thousand two hundred tons of TNT. That could be represented by a cube of high explosives seventy-five feet high, seventy-five feet long, and seventy-five feet thick, as much as could be carried by nearly four hundred trucks, or one medium-sized ship - but conventional explosives could never have detonated with anything approaching this deadly efficiency; in fact, a conventional explosion of this magnitude is a practical impossibility. For all that, it was still a fizzle.

As yet no perceptible physical effects had even left the bomb case, much less the truck. The steel case remained largely intact, though that would rapidly change. Gamma radiation had already escaped, along with X-rays, but these were invisible. Visible light had not yet emerged from the plasma cloud that had only three 'shakes' before been over a thousand pounds of exquisitely designed hardware and yet, everything that was to happen had already taken place. All that remained now was the distribution of the energy already released by natural laws which neither knew nor cared about the purposes of their manipulators.