As part of the optimization of plasma technologies for producing ultrapure materials using plasmatrons, the dependence of the maximum allowable erosion of their electrodes on the operating voltage is substantiated. These results make it possible to speak of high-voltage plasmatrons as priority for the implementation of this technology, since the integral erosion of the electrodes at a fixed power is reduced due to a lower current strength. It is shown that the relative concentration of impurities in the resulting substance does not depend on the current intensity of the plasma torch. As an example, the production of pure white corundum used for medical purposes in microcircuits or in optical devices where a high degree of purity is important is considered. The required purity in the production of corundum by the plasma method is achieved through the use of G000 grade alumina as a raw material with additional purification and the use of a high-voltage plasmatron.