More than six years after it was completed, Oak Ridge National Labs Holifield tandem accelerator has finally reached its design voltage of 25 million volts. The long-awaited event, which took place last month, marked the end of a troublesome startup for the experimental facility, which was designed to conduct experiments involving heavy ions. A sparking “acceleration tube,” which maintains a vacuum around the ion beam, proved the biggest problem for the $8 million machine. The tube had to be redesigned and replaced in 1987, costing the Energy Department an extra $450,000.
While the long delay has been unfortunate, Oak Ridge officials say that it is not unusual for such accelerators. Electrostatic machines are notoriously difficult to design, explains director Charles Jones. For example, he says, a similar accelerator built six years ago in Daresbury, England, has yet to sustain even one-third of its design potential of 30 million volts. Jones ...
