Building for the Theoretical

- Richard Mandel

Research engineering is possibly the ultimate in make-do design. Producing the never-seen-before to demonstrate the unheard-of relies more heavily on ingenuity than the ability to find a supplier of standard parts. The fusion reactor under construction at UCLA in Los Angeles, while serving to prove fusion as being a viable energy resource, may also demonstrate how to succeed on a limited budget.

Professor Bob Taylor, head of the project, has conducted fusion research since the late '70s, and is astonishingly adept at applying inexpensive sources for his exotic machines. When a rival university announced years ago that preheating the plasma with RF energy improves performance, he went home, disassembled his wife's microwave oven for the magnetron, and attached it to the reactor he was using at the time. When his wife came home, all he could say was, "You need a new microwave." Professor Taylor continues to use readily-available microwave oven magnetrons.

Controlled fusion systems have been explored since the 1950s. The basic idea is to tap the energy produced when light atomic nuclei fuse together to create heavier nuclei, a reaction requiring temperatures in excess of 50 x 10⁶ deg. C. In a tokamak design, such as the one at UCLA, a plasma is injected into a toroidal chamber, where magnetic fields pulse the fuel into ionization. The UCLA device will add electrical fields to control the motion of the plasma and reduce turbulence, similar to how the rotation of a smoke ring keeps the particles together.

The new tokamak, with a 2- x 3-meter inside profile, was assembled in sections from inch-thick stainless steel plate. The plates were handled with a crane and a forklift, and alignment was made using a laser taped to the top of a step-motored telescope base from the professor's astronomy hobby. When the last section was set in place, the walls fit with a 2mm precision. Recognizing that the magnets in his machine could be run on lower power than earlier devices, Professor Taylor chose to make them from aluminum rather than traditional copper. The resulting tokamak will cost around $4 million, compared to Princeton's larger unit that cost $1 billion.

For more information, contact UCLA,
310-206-0540. Circle 440.

Originally published in the December 1998 issue of designfax.
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