Though not commonly known outside of Russia and the former Soviet satellite countries, long arc xenon lamps were used for general illumination of large areas such as rail stations, sports arenas, mining operations, and nuclear power plant high bay spaces. These lamps, , literally "lamp xenon DKST" were characterized by high wattages ranging from 2kW to 100 kW. The lamps operated in a peculiar discharge regime where the plasma was thermalized, that is, the electrons were not significantly hotter than the gas itself. Under these conditions a positive current-voltage curve was demonstrated. This allowed the larger common sizes such as 5 and 10kW to operate directly from mains AC at 110 and 220 volts respectively without a ballast – only a series igniter was necessary to start the arc.