A GUN FOR FUSION?

These advances did not come free. The projectile was tiny, of the order of an ounce, and each shot damaged the rail gun beyond repair. The latter fault was at least partially eliminated by researchers at the Los Alamos National Lab by building the gun in sections, but in 1983 the rail gun disappeared from sight (at least from mine), presumably because its development was classified for use in the SDI. Only an occasional news release (such as one by the LANL last month about conserving the energy of the remaining magnetic field for the next shot) reveals that the rail gun continues to be developed.

It has at least three areas of application. The obvious one is artillery: with sufficient velocity, a projectile can pierce any armor.

Second, it has possibilities for nuclear fusion as an energy source. As explained before [AtE Jun 74], one hope of making hydrogen nuclei fuse into helium nuclei (giving off far more energy than fission of heavy elements) is to compress a deuterium pellet by an enormous factor. One way of doing that is to hit the pellet from all sides with tremendous wallops of pulsed laser light. Gigantic machines (such as LLL's "Nova") have been built for this purpose, but success is still far away. An alternative is to shoot the deuterium in some kind of package out of a rail gun; when it hits a wall, it will suffer considerable compression.

Third, and right now most important, the rail gun may play a role for Star Shield. There is no difference between a high-speed bullet hitting a missile and a high-speed missile running into a stationary bullet; the only thing that matters is the difference between the two velocities (which becomes the sum when the velocities have opposite directions). The energy released in the encounter is proportional to the square of that resulting velocity; thus, a bullet from a rail gun might easily destroy a missile.

[More: "Faster than a speeding bullet," Discover, Jan. 1981; "Electromagnetic launchers," Pop. Sci., Nov. 1981; M.N. Kreisler, "How to make things move very fast," Amer. Scientist, Jan./Feb. 1982.]