High voltage direct current power supplies, other than those specified in Dual-Use code 0B001.j.5. or 3A227, having both of the following characteristics— a capable of continuously producing, over a time period of eight hours, 10 kV or more, with output power of 5 kW or more with or without sweeping; and b Current or voltage stability better than 0,1 % over a time period of four hours.