A new method of improving the acceleration voltage stability of Van de Graaff accelerators

摘要

The relative energy stability of Van de Graaff type ion accelerators is typically limited to some 10~(-4). An inexpensive possibility to improve this situation was developed at the Forschungszentrum Dresden-Rossendorf. The method refers to the relatively stable periodic pattern of the acceleration voltage fluctuation in such accelerators. Future values of that fluctuation can be predicted with a high degree of certainty and can taken into account in the belt generator control in spite of the belt convolution caused fundamental reaction delay. The microcontroller based implementation of a "predictive fluctuation compensation" improves the relative acceleration voltage short time stability by a factor of 3-6 to well below 10~(-4).