The New Large Tandem Electrostatic Accelerators

Of the five large electrostatic tandem accelerators listed in Table 1, four have undergone column voltage tests and three are presently running commissioning teats with full beam capability. None of the machines has yet to achieve the full rated terminal potential with acceleration tubes installed. At this time each of these latter three machines has reached approximately 90% of full rating. The column voltage tests on these machines have given good assurance of the voltage holding capability of the basic generator structure. The ability to reach design voltages now depends on successful performance of the acceleration tubes. Although no clear sign of total voltage effect is indicated at this time, that would lead to degrading the rated tube gradients, the concern remains over the effects of the large amount of stored energy present in these accelerators and the effect of the huge currents generated during voltage breakdown. Although full rated voltages on these new large machines will undoubtedly take time and patience to achieve, we can expect the first of these machines to begin operating for research purposes during the present year. The era of the large tandems has, in fact, begun.