A device is disclosed for generating a stable high voltage, namely a high-voltage DC generator for a particle beam apparatus. A method is also disclosed for generating a stable high voltage for a particle beam apparatus. The high-voltage DC generator has a controllable voltage source, which is connected to an amplifier. The high-voltage DC generator ensures that fluctuations of the smoothed high voltage are detected by a capacitive divider and supplied to the amplifier. The amplifier controls the controllable voltage source in counterphase. The voltage of the controllable voltage source is superimposed on the smoothed high voltage. The sum of the voltage of the controllable voltage source and the smoothed high voltage forms the generated and stable high voltage, which is supplied to a particle beam apparatus.